CARE CALL SYSTEM

Abstract

 A care call system comprises:
- a call button (101);
- a cable (121) with plug (131), connected to the call button (101); and
- a wall module (141-143) with negative plug (151-155) for the plug (131).
The call button (101) comprises a call actuator (111), which enables to call a care provider from a room. The call actuator (111) comprises at least one call switch (203) and at least one detection switch (204), the respective signals of which are transmitted via the cable (121) and plug (131) to the wall module (141-143). The call actuator (111) comprises one or more normally closed switches (203) as call switch and one or more normally open switches (204) as detection switch, or vice versa.

Description

Technical field

[0001] The present invention relates to a care call system that is installed in healthcare institutions and hospitals so that a person requiring care or a patient can call a health care provider from their room.

Prior art

[0002] A care call system, sometimes also called a care calling system or a nurse call system, comprises among other things a call button and a wall socket, also called wall module. The wall module may or may not be integrated in a room module or room terminal, a larger apparatus that for example also comprises a display screen and may be combined in one and the same framework with yet other appliances for example such as an intercom module. A cable with a plug connects the call button to the wall module. For this purpose the wall module comprises one or more negative plugs in which the plug can be inserted in order to connect the call button. The wall module may additionally be connected electrically to a call lamp that is placed at the level of the room door in the corridor of the healthcare institution so that a health care provider can see from the lamp from which room a call has been initiated. In more advanced call systems the wall module may be connected to a central management system so that a health care provider or security officer can monitor and trace incoming care calls from a central point.

[0003] The call button that forms part of a care call system comprises at least one push button or actuator that can be used by the person requiring care to initiate a care call or emergency call, and a reassurance lamp that comes on at the moment when the call is passed on to the system, to confirm the care call. It is very important that these basic functions work very reliably. In the case of an emergency situation, whether or not a care call is sent out may make the difference between life or death for the person requiring care. The reliability requirements that a care call system must meet have therefore been standardized, for example in German standard DIN VDE 0834-1 from July 2016. This German standard stipulates among other things that the switch or the contact element that is used for the call function must be a normally closed contact, so that detection of defects in the wiring is made possible. The German standard does not, however, provide any mechanisms for detecting a number of simple faults such as a blocked or defective push button.

[0004] US patent application US 2019/0172322 A1, entitled "Patient Support Apparatuses with Reconfigurable Communication" describes a patient support apparatus an example of which corresponds to hospital bed 20. Fig. 4 of US 2019/0172322 A1 illustrates the coupling between hospital bed 20 and a care call system in a care facility. This coupling comprises a wall module 80, a cable 80 with first and second connectors 88, 90, and cable interface 92 on the hospital bed 20. Wall module 80 is further connected to a nurse call system 62. Fig. 5 of US 2019/0172322 A1 describes control system 98 mounted on the hospital bed 20 in more detail. This control system 98 comprises the cable interface 92 for connector 88, a plurality of switches 118a-118d, a controller 100, a memory 112, and a call actuator 108 (a button or the like). The switches 118a-118d and corresponding pins (Pin 19, Pin 28, Pin 16, Pin 29, Pin 3, Pin 27, Pin 30, Pin 31) in cable interface 98 of the hospital bed ensure a correct transfer of information from the hospital bed 20 to the nurse call system 62, as explained in [0058] and [0059] of US 2019/0172322 A1. The switches 118a-118d are electronic switches that emulate the behaviour of mechanical switches under control of software. According to [0058] and [0059], switch 118a (connected to the pins labelled Pin 19 and Pin 28) is used to inform the nurse call system 62 about the state of one or more lights, switch 118b (connected to the pins labelled Pin 16 and Pin 29) is used to inform the nurse call system 62 about when a caregiver has answered a nurse call request, switch 118c (connected to the pins labelled Pin 3 and Pin 27) is used to transfer a nurse call request to nurse call system 62. The rest state or neutral state of switch 118c, i.e. the state of switch 118c when no nurse call is detected, is either normal-open or normal-closed. The desired neutral state of each of the switches 118a-118d depends on the nurse call system 62 where wall module 80 and consequently also cable interface 98 on hospital bed 20 is coupled to. Paragraph [0060] of US 2019/0172322 A1 explains that controller 100 reads the desired configuration settings for the switches 118a-d from memory 120 and configures the switches 118a-d accordingly. This way, the switches 118a-d of an electrical interface of a hospital bed 20 can be configured in view of the nurse call system 62 where it is coupled to in a particular healthcare facility. Hospital bed 20 hence can be coupled to different nurse call systems from different nurse call system manufacturers, being the technical problem that US 2019/0172322 A1 attempts to solve (see [0004] or [0052] of US 2019/0172322 A1). US 2019/0172322 A1 however does not solve the problem of detecting or preventing single faults such as a blocked or defect call button.

[0005] Besides the call function and reassurance lamp, other functions have also recently been integrated in care call systems. Thus, control buttons are often provided in the call button for operating comfort functions in the room, for example such as for switching on and switching off lighting in the room, for operating roller shutters or a sunblind, etc. Further functions are then integrated in the wall module of a care call system, such as pull-out detection, which determines when the plug of a call button has come loose from the negative plug, and/or a detection function for other appliances, which determines that for example a monitoring appliance has been connected to a negative plug of the wall module instead of a call button. This allows the care call system to be used as well for connecting other appliances present in the room of the person requiring care, for example such as a heart beat monitor, and/or to use the care call system for operating all kinds of home electronics functions present in the room of the person requiring care, for example such as lighting, sunblind, ventilation, radio, etc. Orientation lighting is often also integrated in the call button of a care call system, for example a soft light that stays on permanently and ensures that the button for operating the bed light is easy to find again in the dark.

[0006] A consequence of the integration of more and more functions in the care call system is that the cable and plug that are used for connecting the call button to the wall module, as well as the negative plug and the logic in the wall module are becoming increasingly more complex and more expensive. The number of electrical conductors or wires in the cable increases, just like the number of pins in the plug and the number of pin contacts in the negative plug. The number of plug pins and the number of electrical conductors in the cable is for example up to 10 or more when the call button also controls, besides the call function and the reassurance lamp (which requires a line pin, earth pin and control pin), four other comfort functions (for example room lighting, sunblind up, sunblind down, and sunblind stop, which each require a pin on the plug), controls orientation lighting (via a bed light pin), and the wall module implements a monitoring appliance detection (via a monitor pin) and pull-out detection (via a pull-out pin). These kinds of 10-lead cable and 10-pin plug are expensive, complex and less reliable owing to the number of components. The aim is for all pluggable appliances (a call button, a handset, a monitoring appliance) to be able to use the same cable so that this made-to-measure cable can be made in large volume and cost-effectively.

[0007] There is thus a need for an improved care call system that eliminates or mitigates one or more shortcomings of existing care call systems. The improved care call system should be more reliable, for example in the case of simple faults such as a blocked call button, and/or should be less complex. It is desirable that in particular the cable, plug and negative plug should contain fewer components, for example fewer electrical conductors, fewer pins, and/or fewer pin contacts, to increase their reliability and to lower their cost. It is thus an aim of the present invention to provide an improved care call system of this kind.

Summary of the invention

[0008] According to a first aspect, the invention relates to a care call system as defined in claim 1, said care call system comprising:

• a call button;
• a cable with a plug, wherein said cable is connected to said call button; and
• a wall module with a negative plug for said plug,

wherein said call button comprises a call actuator, enabling a patient to call a care provider from a room,

wherein said call actuator comprises at least one call switch and at least one detection switch, the respective signals of which are transmitted via said cable with said plug to said wall module, and

wherein said call actuator comprises one or more normally closed switches as call switch and comprises one or more normally open switches as detection switch, or vice versa, such that said detection switch allows to detect that said call switch is faulty and, conversely, said call switch allows to detect that said detection switch is faulty;

wherein a normally closed switch in rest state makes a connection between two contacts, and breaks the connection when said call actuator is pressed in; and

wherein a normally open switch in rest state does not make any connection between two contacts, but does when said call actuator is pressed in.

[0009] The improved care call system according to the present invention thus comprises at least one call button, a cable with a plug, and a wall module with a negative plug. The care call system may in addition of course comprise other components such as a central management system, wired and/or wireless call buttons, a call lamp, etc. The plug and the negative plug correspond to a male and a female connector respectively, typically a multipin connector, wherein the male connector comprises several pins (projecting electrical pin connectors) and the female connector comprises several pin contacts (for example inward electrical bushes or contact surfaces). The plug and the negative plug may be connected to each other by pushing the plug into the negative plug. This implies that the negative plug comprises, for each pin of the plug, an inward pin contact in the corresponding position. It is not excluded that the negative plug in addition comprises extra inward pin contacts, as will be explained hereunder. The cable with the plug may or may not be connected detachably to the call button. The cable comprises a number of electrical conductors, typically wire conductors, wherein the number of conductors is greater than or equal to the number of pins on the plug. Preferably the cable has a number of wire conductors that is equal to the number of pins of the plug. On the plug side, each of the conductors is then connected to one pin of the plug. On the call button side, the conductors are connected to a printed circuit board (PCB), on which the electronic components of the call button are also to be found. This connection to a printed circuit board may for example be achieved with a special PCB connector or with soldered contacts.

[0010] The call button in the care call system according to the present invention comprises a call actuator or push button that will be used by the patient or a person requiring care in order to initiate a care call. In other words the call actuator provides the basic function of the care call system, namely to call a nurse or care provider from the room. According to the present invention the call actuator comprises at least two different types of switches: one or more call switches are of the first type and generate the call signal; one or more detection switches are of the second type and generate a detection signal. The detection switch makes it possible to detect that the call switch is faulty and, conversely, the call switch makes it possible to detect that the detection switch is faulty. It is important that the call switch or switches and detection switch or switches are of a different type. Thus, at least one call switch is of the normally closed type and at least one detection switch is of the normally open type, or vice versa. The normally open switch(es) and normally closed switch(es) preferably are mechanically connected. In the rest state, a normally closed switch makes a connection between two contacts, and breaks the connection when pressed. At the moment when the actuator cap of the call actuator is pushed in, the connection is broken, and a call signal is sent. An embodiment of the care call system wherein the call switch is closed in the normal state allows defects in the cable to be detected, so that the care call system is able to satisfy German standard DIN VDE 0834-1. In the rest state, a normally open switch does not make any connection between two contacts, but does when pressed in. At the moment when the actuator cap of the call actuator is pushed in, the connection is made between the two contacts and a detection signal is sent. The normally open switches may for example be configured as carbon pads, placed under the actuator cap so that when the actuator cap is pressed they will close an electric circuit. As the carbon pads wear, their resistance increases. The normally open switches may also be configured differently, for example as metal contact switches, or with contacts of conductive inks, the so-called membrane switches. The normally closed switches may for example be configured as a reed switch, dome switch or piezo switch. Either way, the normally closed switches and normally open switches consist of a different technology and they have different failure mechanisms as a result of wear, deformation, corrosion, etc. Thus, through wear or as a result of extreme compressive forces the actuator cap may be deformed so that the normally closed switch becomes a normally open switch. As a result of the different technology and different failure mechanisms, the call switch and the detection switch or switches will not fail at the same time, so that failure of one type of switch or switches can be detected by the signals coming from the other type of switch or switches.

[0011] One advantage of the present invention is thus that the failure mechanism of the detection switch or switches differs from the failure mechanism of the call switch or switches, so that the chance of both types of switches failing at the same time and in the same way is non-existent. By providing one or more detection switches, making use of a different technology than that which is used for the call switch or switches, and connecting the detection switch or switches to a separate pin of the plug so that besides the call signal, also a detection signal is transmitted from the call button to the wall module, a more reliable care call system is produced. The cable of this more reliable care call system comprises at least four conductors to make the basic function, namely the call function, possible: a conductor that is responsible for the electrical supply and so is connected to a line pin in the plug, a conductor that is responsible for the electrical earthing and so is connected to an earth pin in the plug, an electrical conductor that transmits the call signal from the call button to the wall module, for which it is connected to a call pin in the plug, and a conductor that transmits the detection signal from the call button to the wall module, for which it is connected to a detection pin in the plug.

[0012] In one embodiment of the care call system, when the person requiring care operates the call actuator of the call button, in other words presses the call push button, activation of the call switch or switches will occur after the detection switch or switches have been activated. When the person requiring care releases the call actuator of the call button, deactivation of the call switch or switches will occur before the detection switch or switches are deactivated. The two are of course interchangeable. Owing to the different technology that is used for call switch or switches and detection switch or switches, there is anyway a time difference between the activation of the two and a time difference between deactivation of the two. When a normally open switch is configured as a carbon pad, it is known that through wear of the carbon pad, the resistance increases. After filtering and after controlling the call signal and detection signal by a comparator, the time difference between the two signals will also change by this change in resistance. The time difference may thus also be viewed as a measuring point for the wear of the normally open switch and may be used as a timely indication of when the normally open switch and/or the whole apparatus needs replacing.

[0013] In a possible embodiment of the care call system according to the present invention, defined in claim 2, said call actuator comprises one normally closed switch, several normally open switches and an actuator cap, and said normally open switches are regularly spaced round said normally closed switch under said actuator cap, or vice versa.

[0014] The normally closed switch is thus preferably surrounded on the printed circuit board by several, for example four, normally open switches, which are regularly spaced in a circle round the normally closed switch. The reverse is of course also possible. With a multiple, for example four-fold, configuration of the normally open switches, there is an increased chance that on pressing the actuator cap, at least one of them is operated, and thus the detection signal is also sent. This also increases the reliability, because it is unlikely that all normally open switches would fail at the same time.

[0015] In a possible embodiment of the care call system according to the present invention, defined in claim 3:

• said call button further comprises a reassurance lamp that is switched on in the case of a call and for this is connected electrically to a control pin in said plug, which is also used as a line pin;
• said wall module comprises a switchable supply connected to the corresponding line pin contact in said negative plug, also the corresponding control pin contact for said reassurance lamp; and
• said switchable supply comprises the parallel connection of an electrical resistance or power source and a switch, coupled to said control pin contact, wherein said switch turns said reassurance lamp on and off.

[0016] By providing a switchable supply in the wall module, the function of the reassurance lamp can be integrated in the call button without having to provide additional electrical conductors in the cable or additional electrical pins in the plug. The total number of electrical conductors in the cable and the total number of electrical pins in the plug may thus remain limited to four for a call button that only performs the call function with reassurance lamp. The reassurance lamp may be placed in the call button between the already existing line pin and the earth pin. The reassurance lamp may be configured as the series connection of one or more LEDs. The parallel connection of resistance and switch ensures that the supply voltage is applied completely (switch closed) or partly (switch open) to the line pin contact. As soon as a call signal is received by the wall module, the switch is closed so that a sufficiently high supply voltage is applied to the line pin to illuminate the reassurance lamp. A processor or other logic present in the wall module can then control the switch so that the reassurance lamp will blink in a rhythm in accordance with current standards, for example the rhythm stipulated by the aforementioned German VDE standard. So long as no call signal is received, the switch remains open and a voltage level will be applied via the parallel resistance to the line pin that is too low to illuminate the reassurance lamp at full strength (it does remain easily visible in the dark in compliance with the VDE standard).

[0017] In a possible embodiment of the care call system according to the present invention, defined in claim 4:

• said call button further comprises an orientation lamp that stays on permanently and for this purpose has a parallel connection to said reassurance lamp, between said control pin and an earth pin of said plug.

[0018] In fact, the function of the orientation lamp or the so-called bed light can also be achieved without adding additional electrical conductors to the cable and/or without adding additional pins to the plug. The orientation light may for example be achieved by connecting a single LED, for example an LED that produces warm white light, in parallel with the series connection of 4 red LEDs that produce the reassurance light for a care call. The LED that forms the orientation lamp is then placed between the line pin already present (also control pin for the reassurance light) and the earth pin already present. Preferably an electrical resistance (or power source) is connected in series to the LED that forms the orientation lamp. The switchable supply in the wall module is switched between two voltage levels wherein the first voltage level illuminates the 4 LEDs that form the reassurance lamp and the second voltage level does not illuminate the 4 LEDs that form the reassurance lamp. Both voltage levels may, however, be selected to be high enough for the parallel-connected LED that forms the orientation lamp to be illuminated permanently. Owing to the resistance (or power source) that is connected in series to the LED that forms the orientation lamp, the increase in current at the moment when the switch is closed will be led through the 4 LEDs that form the reassurance lamp. In this way, in the call button the call function with reassurance lamp can be combined with the bed light function, while use is still made of four wire conductors and four contact pins.

[0019] In a possible embodiment of the care call system according to the present invention, defined in claim 5:

• said call button further comprises one or more function buttons for operating respectively one or more comfort functions in said room, and said call button comprises a resistance circuit connected electrically to one pin in said plug, called comfort pin;
• said wall module comprises an electrical currentmeter or voltmeter coupled to the corresponding comfort pin contact in said negative plug; and
• said function buttons switch respective parts of said resistance circuit on or off.

[0020] By using a resistance circuit, a series connection or parallel connection of electrical resistances, the operation of one or more comfort functions present in the room can be integrated in the call button of the care call system, whereas only one electrical conductor has to be added to the cable of the care call system and only one extra pin and pin contact has to be provided in the plug and negative plug of the care call system. In one embodiment, the resistance circuit may for example be configured as a series connection of several electrical resistances between the comfort pin and the earth pin, as in the figures. In another embodiment the resistance circuit is a parallel connection of several electrical resistances between the comfort pin and the earth pin. In yet another embodiment the resistance circuit is a combination of a series connection and parallel connection of several electrical resistances between the comfort pin and earth pin. The function buttons or switches that are provided in the call button for operating the various comfort functions are connected between respective parts of the resistance circuit so that each function button or switch will either switch off, or activate on pressing or operating the function button, a respective part of the resistance circuit. Each function button or switch will thus switch on or switch off a respective part of the resistance circuit when pressed. The resistance that is seen from the wall module recognizes as many different levels as there are function switches. In the wall module of this embodiment of the care call system, a current or voltage source is connected to the comfort pin contact in such a way that when the plug is inserted in the negative plug, an electric current is sent via the comfort pin through the resistance circuit. The level of the electric current and the voltage on the comfort pin will of course depend on the resistance of the resistance circuit and thus change each time a function button is depressed. It is then sufficient for the electric current through the comfort pin or the voltage on the comfort pin to be measured directly or indirectly in order to determine which parts of the resistance circuit are short-circuited, and thus determine which function button has been pressed. The number of function buttons that can be incorporated in this way in the call button with minimum impact on the complexity and cost of the cable, plug and negative plug is in principle unlimited. In practice, a few function buttons will be integrated in the call button, for example four function buttons, which are used respectively to lower the sunblind, to raise the sunblind, to switch the lighting above the bedhead (bed light) on and off, and to switch the main lighting in the room on and off.

[0021] In a possible embodiment of the care call system according to the present invention, defined in claim 6, said call system comprises a pull-out detection, which is achieved with an additional resistance in said resistance circuit.

[0022] The pull-out detection is an important function because it makes it possible to establish that the plug or cable of a call button has been pulled out or has come loose, so that the call button can no longer send a care call. If pull-out detection is provided, a care provider or person present in the central monitoring room will be informed automatically that a particular call button in a particular room is no longer connected to the wall module, and the care provider or another person can go and rectify this fault immediately. In an advantageous embodiment of the care call system, the pull-out detection may be accomplished without adding an electrical conductor in the cable and without adding a pin and pin contact in the plug and negative plug of the care call system. In this embodiment, the pull-out detection is accomplished by adding a resistance to the resistance circuit that is connected to the comfort pin. This additional resistance provides an additional resistance level, thus at an additional current level that can be measured on the comfort pin at the moment when no comfort button is pressed, so that besides the pressing of the various comfort buttons, merely the presence or absence of the call button can also be detected. The additional resistance ensures that the resistance circuit is always closed, and thus an electric current always goes through the comfort pin when the plug is inserted in the negative plug. On pressing a comfort button, a part of the resistance circuit is short-circuited (or switched off) and the current level will thus change. Without pull-out detection, it is also possible to choose an open resistance circuit, through which no electric current passes so long as no comfort button is pressed. It should be pointed out that the pull-out detection in existing systems is sometimes realized by measuring the current through the normally closed switch. However, this does not allow a distinction to be made between pull-out of the call button and a defective call button, which is possible in the embodiment described above according to the present invention.

[0023] In a possible embodiment of the care call system according to the present invention, defined in claim 7:

• said wall module comprises a sensor, which measures the electric current through or voltage on said comfort pin contact directly or indirectly; and
• said wall module comprises a processor, coupled to said sensor and configured to determine, from the sensor measurement, which of said function buttons was activated and/or to determine that said plug has been separated electrically from said negative plug.

[0024] In fact, an embodiment of the care call system wherein the call button comprises a resistance circuit coupled to a comfort pin, preferably also comprises a sensor in the wall module, where it measures, directly or indirectly, the current through or the voltage on the comfort pin contact, and transmits the measurement to a processor, for example a microcontroller, in the wall module for interpretation. From the measured current level or voltage level, the processor is able to identify whether and which comfort function button was operated on the call button and can operate the corresponding comfort function, for example the sunblind. The processor can also identify, from the measured current level or voltage level, whether a call button is connected correctly via the plug to the wall module, or whether the plug has come loose or has been pulled out. The processor can use this information to send an alarm to a security officer or care provider, who can rectify the fault by inserting the loose plug back into the negative plug.

[0025] In another possible embodiment of the care call system according to the present invention, defined in claim 8:

• said wall module comprises a duplicate resistance circuit with power source; and
• said wall module comprises a comparator bench, which compares the voltage on said comfort pin contact with voltage levels obtained from said duplicate resistance circuit to determine which of said function buttons was activated and/or to determine that said plug has been separated electrically from said negative plug.

[0026] In fact, instead of a sensor that measures the voltage on the comfort pin and transmits the measurement to a processor, the wall module may also be equipped with other logic that allows the resistance level of the resistance circuit to be detected, for example a resistance circuit that is a duplicate of the resistance circuit in the call button. A power source that sends an electric current into the duplicate resistance circuit then makes it possible to compare the voltage level that is reached in different parts of the duplicate resistance circuit with the voltage on the comfort pin. This comparison can take place by means of a comparator bench. The comparison makes it possible to establish which part of the resistance circuit in the call button was switched off or switched on, and thus also establish which comfort function button was pressed. The comparison also makes it possible to establish whether the plug and negative plug are connected correctly if the resistance circuit and duplicate resistance circuit comprise the additional resistance that makes pull-out detection possible. In this way, the need to provide a processor in the wall module can thus be avoided in an embodiment of the care call system that nevertheless makes operation of comfort functions via the call button possible. This lowers the cost price and increases the reliability by excluding software bugs.

[0027] In a possible embodiment of the care call system according to the present invention, defined in claim 9:

• said negative plug comprises a monitor pin contact; and
• said wall module comprises logic connected electrically to said monitor pin contact for detecting that a monitoring appliance has been connected to said negative plug and/or for detecting that an alarm has been triggered on a monitoring appliance connected to said negative plug.

[0028] It is desirable that the negative plug in the wall module may not only be used for connecting a call button to it, but may also be used for connecting a monitoring appliance thereto, for example a heart rhythm monitor or infusion monitor, in such a way that an alarm signal from said monitoring appliance can be transmitted to a central management system without additional wiring and negative plugs having to be provided. In an advantageous embodiment of the care call system that makes this possible, the negative plug comprises an extra pin contact, the so-called monitor pin contact. The monitoring appliance is connected to the wall module via a special monitor plug and monitor cable. The plug of a monitoring appliance comprises the corresponding monitor pin whereas the plug of a call button does not comprise the corresponding monitor pin. The call pin is thus preferably not used for monitoring. This is because we want to avoid a monitoring alarm being regarded accidentally as an ordinary care call (or vice versa), to make it possible in a simple manner to take in a monitoring alarm without having to distinguish whether it has come from a normally open or normally closed contact, and to avoid having the monitoring function breach the VDE protocol on the call pin. By detecting a monitoring appliance via the comfort pin contact, as described hereunder, false calls are also avoided. Because the same cable is used for a call button and monitoring appliance, for a call button the electrical wire for monitoring will not be connected. There is a risk of this wire picking up external interference and triggering a monitoring alarm as a result. To summarize, for a monitoring appliance, in theory three configurations are thus possible: the comfort pin contact can be used to detect the type of apparatus, whereas an alarm call is detected via the normally open or normally closed contact, but this involves the risk of interference with the VDE protocol of a call button; the alarm call may be received via the monitor pin contact without detection of the type of apparatus, but then pull-out warning is only possible for a monitoring appliance with normally closed contact; finally the type of apparatus may be detected via the comfort pin contact, whereas an alarm call is received on the monitor pin contact, which is the most advantageous embodiment.

[0029] In a possible embodiment of the care call system according to the present invention, defined in claim 10:

• said logic forms part of said processor and said sensor can differentiate an additional electric current level through said comfort pin contact when said monitoring appliance is connected via a special monitor cable and special monitor plug to a monitor negative plug in said wall module, wherein said monitor cable or said monitor plug comprises an identification resistance between comfort pin and earth pin of said monitor plug.

[0030] If the monitoring appliance is equipped with a normally closed contact that is connected via the monitor cable to the monitor pin in the monitor plug, the wall module will detect an electric current through the monitor pin at the moment when the monitoring appliance is connected. This electric current is absent if a call button is connected. However, when the monitoring appliance is equipped with a normally open contact that is connected via the monitor cable to the monitor pin in the monitor plug, the wall module will not detect an electric current at the moment when the monitoring appliance is connected and thus fails to make a difference with a call button. For this reason, in a preferred embodiment the monitor cable or monitor plug will comprise an identification resistance. This identification resistance is connected between the comfort pin and the earth pin in the monitor plug (or between the corresponding wire conductors in the monitor cable), and the identification resistance has a resistance value that differs from all resistance values that can be produced by the resistance circuit for the comfort functions (whether or not with pull-out detection) from the call button. This identification resistance also allows the wall module to detect that a monitoring appliance with normally open contact has been connected, because the connection of said monitoring appliance via the monitor cable/monitor plug with identification resistance will give rise to an additional current level through the comfort pin. This additional current level can be detected by a sensor/processor in the wall module, or by alternative logic such as the duplicate resistance circuit and comparator bench already described above.

[0031] A possible embodiment of the care call system according to the present invention, defined in claim 11, further comprises:

• a digital handset with a call actuator, a user interface, and a microcontroller and/or Field-Programmable Gate Array (abbreviated to FPGA) coupled to said call actuator and said user interface; and
• a cable with handset plug, wherein said cable is connected to said digital handset,

and said wall module therein comprises the following:

• a Controller Area Network bus, called CAN bus;
• a Low-Voltage Differential Signal transmitter/receiver, called LVDS transm itter/receiver;
• a handset negative plug that integrates said negative plug for said call button with two CAN pin contacts connected electrically to said CAN bus and four LVDS pin contacts connected electrically to said LVDS transmitter/receiver and wherein two of the four said LVDS pin contacts are also used respectively as line pin and earth pin for said call button when coupled to said handset negative plug.

[0032] In this way, one and the same negative plug in the wall module can be used for connecting both a call button and a digital handset, which besides a call actuator also comprises a more complex user interface that makes it possible to exchange sound (audio) and image (video). One and the same 6-wire cable may also be used for the connection between call button and wall module, and the connection between digital handset and wall module (although with a different plug). The advantage of this is that for stock management and price, one type of cable scores much better than two different types of cable, whether or not with even more wires. The digital handset also allows a care call to be sent but is moreover a more complex apparatus that also supports functions such as telephony, intercom, music in the room, video communication, etc., and for this purpose is equipped with a CAN bus, an LVDS transmitter/receiver, and a more advanced user interface such as a screen and keyboard or a touchscreen. The CAN bus is a digital 2-wire connection that is used for the call function and reassurance lamp, and which thus requires 2 pins in the handset plug and 2 pin contacts in the handset negative plug. The LVDS transmitter/receiver communicates with an LVDS transmitter/receiver in the wall module. The LVDS transformers require 4 pins in the handset plug and 4 pin contacts in the handset negative plug for transmitting an audio and video signal. When the 4, 5 or 6 pins of the embodiments of the plug for the call button described above are also integrated in the handset plug, the line pin that is provided for the call button may also be used as pin for the LVDS transformers and the earth pin that is provided for the call button can also be used as pin for the LVDS transformers. Instead of adding six pins so as to obtain a universal plug that can be used to connect both a call button and a digital handset to the wall module, it is thus sufficient to add 4 pins, so that a plug can be obtained with 8 pins (if the call button only supports the basic functions), 9 pins (if the call button also supports operation of comfort functions and pull-out detection) or 10 pins (if connection of a monitoring appliance is also supported). Accordingly, a negative plug with 8 pin contacts, 9 pin contacts or a maximum of 10 pin contacts may also be obtained, which allows both a call button, monitoring appliance and digital handset to be connected. The cable that is used in said care call system may comprise 6 wires or conductors. Preferably the negative plug of the wall socket fits within the dimensions of a standard wall socket with centre distance of 57 mm or 71 mm. Taking into account the minimum size of the contact surfaces and their distance apart, 10 pins is then roughly the maximum attainable. The problem that arises is thus that owing to the limitations imposed by the centre distance of the wall sockets and the minimum surface area of the contact surfaces, the number of pins of the wall socket is limited to 10. However, other pins are needed for each apparatus, which, when all are counted up, comes to more than 10.

[0033] A possible embodiment of the care call system according to the present invention, defined in claim 12, further comprises:

• a digital handset with a user interface, and a microcontroller and/or Field-Programmable Gate Array (abbreviated to FPGA) coupled to said user interface, wherein said microcontroller is configured to send an identification code via a serial data output; and
• a cable with handset plug, wherein said cable is connected to said digital handset in such a way that said serial data output from said microcontroller is connected to the comfort pin of said handset plug,

and wherein said wall module comprises the following:

• a Controller Area Network bus, called CAN bus;
• a handset negative plug that integrates said negative plug for said call button with two CAN pin contacts connected electrically to said CAN bus;

and wherein said processor in said handset negative plug (808) is configured to detect said identification code on a serial data input.

[0034] In possible embodiments of the care call system, a simpler digital handset is thus connected to the wall module. This simpler digital handset comprises a call actuator, a user interface and microcontroller, but does not support any audio/video communication. The user interface may consist of individual keys, a keyboard, a touchscreen or a combination of these things. The simple digital handset may also further comprise a number of lamps. In order to allow the wall module to detect that said simpler digital handset has been connected, the microcontroller in the simpler digital handset is equipped with a serial data output, which is connected (typically via a serial driver) to the comfort pin in the plug. In this way, the microcontroller is able to send a unique identification for the digital handset to the wall module. This unique identification will be received and transferred, via the sensor that detects changes in current through the comfort pin contact, to a serial data input of the processor in the wall module. The processor in the wall module is able to differentiate reception of a unique identification code on the serial data input from the resistance detection that takes place when a call button is connected (and thus a resistance circuit is connected to the comfort pin) and that takes place when a monitoring appliance is connected (and thus the identification resistance from the monitor cable or monitor plug is connected to the comfort pin).

[0035] In a possible embodiment of the care call system according to the present invention, said wall module comprises two or more negative plugs, identical to said negative plug.

[0036] This embodiment of the care call system thus comprises a variant of the wall module that comprises several negative plugs. Each of these negative plugs can be used for connecting a call button thereto. A multiple-person room that is shared by several patients then only has to be equipped with one wall module.

[0037] In a possible embodiment of the care call system according to the present invention, said wall module comprises two or more negative plugs, at least one of which is identical to said monitor negative plug.

[0038] This embodiment of the care call system again comprises a variant of the wall module that comprises several negative plugs. At least one of the negative plugs may be used for connecting a monitoring appliance thereto, while the second negative plug is used for connecting a call button thereto.

[0039] In another possible embodiment of the care call system according to the present invention, said wall module comprises two or more negative plugs, at least one of which is identical to said handset negative plug.

[0040] In fact, in another conceivable embodiment of the care call system, the wall module again comprises several negative plugs. A first negative plug may then for example comprise six pin contacts, so that a call button or a monitoring appliance may be connected thereto. The second negative plug may comprise ten pin contacts so that a call button, a monitoring appliance or a digital handset may be connected thereto.

[0041] It is obvious that a person skilled in the art, inspired by the foregoing, can conceive other variant embodiments of the care call system wherein the wall module comprises one, two or more negative plugs, and wherein the negative plugs may be of the type with 4 pin contacts (to make the basic functions of care call and reassurance lamp possible), with 5 pin contacts (supplementing the basic functions, also make the operation of comfort functions and pull-out detection possible), with 6 pin contacts (supplementing the basic functions, also make comfort functions and pull-out detection as well as the connection of a monitoring appliance possible), or with 10 pin contacts (besides the connection of the call button and a monitoring appliance, also make the connection of a digital handset possible). Embodiments of the care call system may thus be equipped with a 4-wire cable, a 5-wire cable, or a 6-wire cable, so that in relation to the functions supported, the complexity and the cost of negative plug, plug and cable are minimized in each case. Regardless of the choices at the level of call apparatus or operating apparatus, that apparatus may then always make use of the same custom-made cable. By cleverly combining functions on the plugs and negative plugs, only a limited number of variants are required, namely a version for basic appliances without intelligence (for example a call button or monitoring appliance), a version for a digital handset with more extensive functions including audio, and optionally a version for a digital handset without audio.

[0042] In a possible embodiment of the care call system according to the present invention, defined in claim 13, said wall module comprises a low-pass filter for both the detection signal and the call signal, and said wall module comprises logic configured to measure the time difference between the switching time point, the conditioned call signal coming from said call switch and the corresponding switching time point of the conditioned detection signal coming from said detection switch, in order to detect wear based thereon.

[0043] In fact, under the effect of wear, the switching time points of the normally open switches and the switching time points of the normally closed switches will change with time. When the switching time points are recorded, they can be compared with established threshold values or with historical values. As soon as the course of the differences in switching time points exceeds certain threshold values, the switch or the apparatus of which it forms a part can be replaced, or maintenance or repair may be carried out in order to avoid switch failure. Detecting wear on the basis of the switching time points thus makes predictive maintenance possible, which is important in applications such as care call systems, for which high reliability is required.

[0044] In a possible embodiment of the care call system according to the present invention, defined in claim 14, said wall module comprises logic configured for measuring the change in the time difference between the switching time point called conditioned call signal coming from said call switch and the corresponding switching time point called conditioned detection signal coming from said detection switch, in order to detect wear based thereon.

[0045] The difference between the switching time points of a normally open switch and a normally closed switch changes with time on account of wear. As is explained further hereunder, on pressing the call actuator, the course of that difference will, however, only be determined by wear of the switch that is the most sensitive to wear, for example the normally open switch. With other choices of switches, it could also be that it is the normally closed switch, but that is in practice undesirable because the normally closed switch according to the aforementioned German standard is a basic element in the reliability requirement. The change in the difference between the switching time points of the normally open switches and normally closed switches thus either allows the wear of normally open switches, or the wear of the normally closed switches to be measured. Once again, when this wear exceeds certain thresholds, by means of predictive maintenance it is avoided that a switch will fail. The switch can be replaced in good time, so that the reliability increases.

Brief description of the drawings

[0046] 

Fig. 1 illustrates possible embodiments of the care call system according to the present invention;

Fig. 2 illustrates in detail the call actuator 111 in a possible embodiment of the care call system according to the present invention;

Fig. 3 illustrates the positioning of components of the call actuator on a printed circuit board 201 in the call button in a possible embodiment of the care call system according to the present invention;

Fig. 4 illustrates the cable and plug that connect the call button to the wall module in a possible embodiment of the care call system according to the present invention;

Fig. 5 illustrates a possible embodiment of the call button 503, plug 502 and wall module 501 in a first embodiment of the care call system according to the present invention wherein a 4-wire cable is sufficient;

Fig. 6 illustrates a possible embodiment of the call button 603, plug 602 and wall module 601 in a second embodiment of the care call system according to the present invention wherein a 5-wire cable is sufficient;

Fig. 7A and 7B illustrate a third possible embodiment of the care call system according to the present invention wherein one and the same wall module 701 is connected respectively to a call button 703 or a monitoring appliance 707 via a 6-wire cable;

Fig. 8A, 8B, 8C and 8D illustrate a fourth possible embodiment of the care call system according to the present invention wherein one and the same wall module 801 is connected respectively to a call button 803, a monitoring appliance 807, a digital handset 809 or a simple digital handset 809' via a 6-wire cable;

Fig. 9A-9F illustrate the electrical signals, more specifically the call signal and detection signal, received by the wall module of the call button in various situations in possible embodiments of the care call system according to the present invention;

Fig. 10 illustrates an embodiment of the care call system according to the present invention with wear monitoring and predictive maintenance; and

Fig. 11A-11C illustrate how the electrical signals, more specifically the call signal and detection signal, may be used for wear monitoring and predictive maintenance in embodiments of the care system according to the present invention.

Description of embodiments

[0047] Fig. 1 illustrates a number of possible embodiments for the care call system according to the invention. Thus, Fig. 1 shows a first variant 141 of the wall module, which comprises one negative plug 151 suitable for connection of a call button 101. The call button 101 comprises a call actuator 111, a reassurance lamp 112, and control buttons 113 for comfort functions. The negative plug 151 in this first variant 141 of the wall module comprises six pin contacts so that a six-wire cable 121 and plug 131 with the corresponding six pins may be used to connect the call button 101. Fig. 1 also shows a second variant 142 of the wall module, which comprises two negative plugs, 152 and 153. The first negative plug 152 comprises six pin contacts and is again suitable for connecting a call button 101 by means of six-wire cable 121 and a plug 131 with six pins. The second negative plug 153 also comprises six pin contacts and is suitable for connecting either a call button 101, or a monitoring appliance 102 by means of a plug with six pins. If a monitoring appliance 102 is connected, then it should be possible to make use of a special monitor cable 122 with monitor plug 132. Finally, Fig. 1 also shows a third variant 143 of the wall module, which comprises two negative plugs, 154 and 155. The first negative plug 154 also comprises six pin contacts and is, just like negative plugs 151 and 152, suitable for connection of a call button 101 by means of a six-wire cable 121 and plug 131 with six pins. The second negative plug 155 comprises ten pin contacts. A first set consisting of six of the ten pin contacts allows a call button 101 or a monitoring appliance 102 to be connected by means of a plug with six pins. The cable 122 with plug 132, which is used for connecting a monitoring appliance 102, is possibly once again a special monitor cable. In an alternative embodiment, negative plug 154 will be suitable for connecting a call button or monitoring appliance, and negative plug 155 will be suitable for connecting a call button, monitoring appliance or digital handset. A second set of six pin contacts from negative plug 155 may be used for connecting a digital handset 103. Said digital handset 103 comprises for example a call actuator 114, reassurance lamp 115, control buttons 116 for comfort functions and a user interface 117, for example a touchscreen, and is connected via a six-wire cable 123 and a handset plug 133 with six pins that have different positions than the six pins of plug 131 that is used for connection of a call button 101 or the six pins of plug 132 that is used for connection of a monitoring appliance 102. The first set of six pin contacts (used for connection of a call button or monitoring appliance) and the second set of six pin contacts (used for connection of a digital handset) have two pin contacts in common. For reasons of cost-effectiveness, for six-wire cables 121, 122, 123 the same cable will be used, which can thus be made in larger volume. A care call system that is installed in a healthcare institution may comprise wall modules of one type, for example wall module 142, or may comprise a combination of different types of wall modules, for example a combination of wall modules 141 and 143, depending on the wishes or needs of the healthcare institution. Thus, different room types may be equipped with different types of wall modules. Moreover, one single room may be equipped with several wall modules, which are identical or different. Each of the negative plugs 151, 152, 153, 154, 155 may be connected via a cable 161, 162, 163, 164, 165, for example a standard UTP or Ethernet cable, to a central management system 170 to which the alarm signals or data received from the connected call buttons 101, monitoring appliances 102 and/or digital handsets 103 are transmitted. It is to be noted here that the connection to the central management system 170 is generally made via one or more intermediate steps, for example via bundled units, which pool the information from various units. That one and the same type of cable with a limited number of electrical wires, for example six, can be used for connecting call button 101, monitoring appliance 102 or digital handset 103 to respective wall modules 141, 142, 143, is one of the most important advantages of the present invention. The cables are expensive components that are used in large volume in the installation of a care call system. Limiting the number of electrical wires required therein and using an identical cable for all connections in the care call system contributes greatly to production efficiency and thus also to cost reduction of the care call system.

[0048] Although Fig. 1 shows three different wall modules, a person skilled in the art will understand that other wall modules may also be assembled that comprise one or more negative plugs, usable for connecting a call button and/or a monitoring appliance and/or a digital handset. In addition, a person skilled in the art will understand from what follows that although Fig. 1 illustrates variants of a care call system wherein a six-wire cable is used, variants of the present invention are also conceivable wherein a four-wire cable may be used or a five-wire cable may be used, which would reduce the total cost for the care call system even further.

[0049] Fig. 2 illustrates in detail the call actuator 111 from the call button 101 in Fig. 1. Fig. 3 illustrates the positioning of a number of components of the call actuator 111 on a printed circuit board 201 in the call button 101. The call actuator 111 comprises an actuator cap 206, which fits in an opening provided for it in the housing 202 of the call button 101. The actuator cap is spring-mounted on springs 205 so that the actuator can be pushed in by a person requiring care who wants to send a care call. If no force is exerted on the actuator, the springs 205 return the actuator cap 206 to its rest position. Under the actuator cap 206 there are a normally closed switch 203 and four normally open switches 204. These components are positioned on a printed circuit board 201 in such a way that the normally closed switch 203 is located centrally under the actuator cap 206, and the four normally open switches 204 are regularly spaced in a circle round the normally closed switch 203. The normally open switches 204 and normally closed switch 203 in other words are mechanically connected. Fig. 3 additionally shows four red LED lamps 301, which are also on the printed circuit board 201 and are regularly spaced in a second circle round the normally closed switch 203 so as to form together the reassurance lamp 112 of the call button 101. In the embodiment illustrated in Fig. 2 and Fig. 3, mechanical design requires that on pressing the actuator cap 206, activation of the normally closed switch 203, also called the call switch, will take place after activation of the normally open switches 204, also called the detection switches. Conversely, on releasing the actuator cap 206, with return to the rest position, deactivation of the call switch 203 will take place before deactivation of the detection switches 204. The normal operation of the call actuator 111 is illustrated in Fig. 9A. In this drawing, 901 indicates the signal coming from call switch 203 and 902 indicates the signal coming from detection switches 204. At the moment when call signal 901 increases, for example to the level of the supply voltage VCC, a care call will be sent and the reassurance lamp 301 will be switched on. At the same time, it is established that the detection signal 902 is at 0 V (zero volts), which indicates that the call actuator 111 is functioning correctly.

[0050] The normally closed switch 203 and the normally open switches 204 have a different failure mechanism, so that the signal derived from one of them may be used for detecting failure of the other one, and vice versa. Owing to the use of two different types of switches in the call actuator 111 of the call button 101, a very reliable care call system is realized wherein one or more faults as a result of wear or faulty technology do not lead to a care call being missed. This is illustrated in Fig. 9B-9F, which illustrate in each case situations wherein one or more faults arise in the actuator 111. In Fig. 9B it is assumed that the call switch 203 is faulty and remains in the rest state (closed) at the moment when the actuator 111 is pressed. The call signal 903 derived from call switch 203 thus does not change, whereas detection signal 904 from the detection switches 204 drops back to 0 V. This is detected by the wall module to which the call button is connected. The wall module will send out a care call, switch on the reassurance lamp 301, optionally record an error message in a central databank, and optionally send a message to a person responsible for maintenance of the care call system. Optionally the reassurance lamp may be switched on and off alternately to indicate that faulty operation of the call button 101 has been detected. In Fig. 9C it is assumed that the detection switch 204 and/or the detection wire in the cable is defective, so that there is no change in the detection signal 906 at the moment when the call actuator 111 is pressed. The wall module to which the call button 101 is connected detects an increase in voltage in the call signal 905 coming from the call switch 203 but no voltage change in the detection signal 906 coming from the detection switches 204. The wall module will send out a care call, switch on the reassurance lamp 301, optionally record an error message in a central databank, and optionally send a message to a person responsible for maintenance of the care call system. Optionally the reassurance lamp may be switched on and off alternately to indicate that faulty operation of the call button 101 has been detected. Fig. 9D shows a snapshot wherein a fault occurs in the call switch 203 or the call wire in the cable. As a result, there is an increase in voltage in the call signal 907, but no return to the normally closed state. The detection signal 906 coming from the detection switches 204 does not change, because the actuator 111 has not been pushed in. After a previously defined time-out, the wall module to which the call button 101 is connected will detect the new state. The wall module will send out a service call to report the detected fault, optionally switch on the reassurance lamp 301, optionally record an error message in a central databank, and optionally send a message to a person responsible for maintenance of the care call system. Optionally the reassurance lamp may be switched on and off alternately to indicate that faulty operation of the call button 101 has been detected. In Fig. 9E it is assumed that the call switch 203 and/or the call wire is/are faulty, so that there is no change in voltage in the call signal 909 coming from the call switch 203, whereas a drop in voltage in the detection signal 910 coming from the detection switches 204 is observed. This situation is comparable to that from Fig. 9B, where the call switch 203 became stuck, and the reaction of the wall module will thus be identical to the situation from Fig. 9B. In Fig. 9F it is assumed that wear has occurred, so that activation of the call switch 203 now takes place before activation of the detection switches 204 at the moment when the actuator 111 is pressed, and deactivation of the call switch 203 now takes place after deactivation of the detection switches 204 on releasing the actuator 111. This is detected by the wall module to which the call button 101 is connected as a normal care call but it is also established that the switches in question have suffered wear. The wall module will send out a care call, switch on the reassurance lamp 301, optionally record an error message in a central databank, and optionally send a message to a person responsible for maintenance of the care call system. Owing to the presence of one or more call switches in a first technology (in this case normally closed technology) and one or more detection switches in a second technology (in this case normally open technology), the care call system will continue to function reliably when one or more defects arise. The defective components may be replaced or the call button may be replaced completely without risk that a care call would be missed. In addition, the normally closed and normally open technologies allow wear to be detected in good time so that wear-sensitive components can be replaced before they fail, or the call button subjected to wear can be replaced completely. In addition, the use of normally closed technology for the call switch 203 ensures that the care call system is able to function in accordance with the aforementioned German standard.

[0051] Fig. 4 illustrates the cable 404 and plug 402 that connect the call button 403 to the wall module in a possible embodiment of the care call system according to the invention. In this embodiment, the cable 404 comprises five electrical wires or conductors 431, 432, 433, 434, 435 each connected to a respective pin contact 421, 422, 423, 424, 425 in the plug 402. The electrical conductors 431-435 are connected in the call button 403 to respective contact points 411, 412, 413, 414, 415. The connection to these contact points may be fixed or separable, depending on whether 401 is a fixed connector or pull-out connector. The first conductor 431 is connected to a control contact point 411, the second conductor 432 is connected to an earth contact point 412, the third conductor 433 is connected to a normally closed call contact point 413, the fourth conductor 434 is connected to a comfort contact point 414, and the fifth conductor 435 is connected to a normally open detection contact point 415. The call button 403 comprises a call actuator with normally closed switch 441, connected between the normally closed call contact point 413 and earth contact point 412, and normally open switch 442, connected between the normally open detection contact point 415 and earth contact point 412. The call button 403 further comprises a reassurance lamp 430, connected between the control contact point 411 and earth contact point 412, and a resistance circuit 450, connected between the comfort contact point 414 and earth contact point 412. One or more comfort switches, with which call button 403 is equipped to operate one or more comfort functions in the room, switch respective parts of the resistance circuit 450 on or off.

[0052] Fig. 5 shows the call button 503, plug 502 and wall module 501 in a first embodiment of the care call system according to the invention wherein a 4-wire cable is sufficient to connect the call button 503 to the plug 502. The cable itself is not shown but is thus located between the call button 503 and the plug 502. The plug 502 comprises four contact pins 521, 522, 523 and 524 that connect to four pin contacts 581, 582, 583, 584 of the negative plug 508 with which wall module 501 is equipped. Contact pin 522 and the corresponding pin contact 582 are the electrical earth, respectively on the side of the call button 503 and the side of the wall module 501. Contact pin 521 is the line pin and/or control pin. Between the line pin 521 and the earth pin 522, the call button 503 comprises a power source 537 or resistance and the parallel connection of on the one hand a reassurance lamp 531-534 and on the other hand the series connection of an orientation lamp 535 and electrical resistance 536 or power source. The reassurance lamp is realized with 4 red LEDs, 531, 532, 533 and 534. The orientation lamp is realized with 1 white LED 535. The call button 503 further comprises a normally closed switch 541 between the so-called call pin 523 and the earth pin 522, and a normally open switch 542 between the so-called detection pin 524 and the earth pin 522. The normally closed switch 541 and normally open switch 542 form part of the call actuator of the call button 503, and correspond for example to the switches 203 and 204 of the call actuator 111 illustrated in Fig. 2. The wall module 501 comprises a switchable supply 510 (of 24V) that is connected via an electrical resistance 512 or power source to line pin contact 581. The electrical resistance 512 can be short-circuited by a switch 511 that is controlled by logic 516, for example a microprocessor, in the wall module 501. The logic 516 is connected to the call pin contact 583 and the detection pin contact 584 so that the logic 516 receives the call signal coming from normally closed call switch 541 and the detection signal coming from normally open detection switch 542, can interpret these signals, and based on these signals can control the switch 511. The electrical resistance 512 is dimensioned so that with switch 511 open, a limited electric current is sent through line pin 521. This current is shared in the call button 503 between the reassurance lamp 531-534 and the orientation lamp 535 so that both light up softly. As soon as the logic 516 detects the call signal coming from normally closed switch 541 or the detection signal coming from normally open switch 542, the wall module 501 will send an alarm signal to a central management system to which it is connected, or - in a simpler care call system - to an alarm lamp that is switched on, for example in the corridor of a healthcare institution at the level of the room of the person requiring care. The switch 511 will also be closed, optionally after communication with the central management system. As a result, electrical resistance 512 is short-circuited and the electric current through line pin 521 is increased. The electrical resistance 536, interacting with the relatively constant voltage across the reassurance lamp 531-534, prevents the increase in current passing through the orientation lamp 535. The whole increase in current thus goes through the reassurance lamp 531-534 in call button 503, which will now light up brightly to confirm to the person requiring care that a care call has been sent. According to the embodiment illustrated in Fig. 5, a very reliable care call system is thus produced, which fulfils the basic functions of care call, reassurance lamp and orientation lamp, whereas the cable and plug that are used for connecting the call button 503 to the wall module 501 can be produced very cost-effectively: only 4 electrical wire conductors and only 4 contact pins are required.

[0053] Fig. 6 shows the call button 603, plug 602 and wall module 601 in a second embodiment of the care call system according to the invention wherein a 5-wire cable is sufficient for connecting the call button 603 to the plug 602. The cable itself is not shown but is thus located between the call button 603 and the plug 602. The plug 602 comprises five contact pins 621, 622, 623, 624 and 625, which are connected to five pin contacts 681, 682, 683, 684 and 685 of the negative plug 608 with which wall module 601 is equipped. Contact pin 622 and the corresponding pin contact 682 are the electrical earth, respectively on the side of the call button 603 and the side of the wall module 601. Contact pin 621 is the line pin or control pin. Between the line pin 621 and the earth pin 622, the call button 603 comprises a power source 637 and the parallel connection of on the one hand a reassurance lamp 631-634 and on the other hand the series connection of an orientation lamp 635 and electrical resistance 636. The reassurance lamp is realized with 4 red LEDs, 631, 632, 633 and 634. The orientation lamp is realized with 1 white LED 635. The call button 603 further comprises a normally closed switch 641 between the so-called call pin 623 and the earth pin 622, and a normally open switch 642 between the so-called detection pin 624 and the earth pin 622. The normally closed switch 641 and normally open switch 642 form part of the call actuator of the call button 603, and correspond for example to the switches 203 and 204 of the call actuator 111 illustrated in Fig. 2. The call button 603 further comprises a resistance circuit 650 that is connected electrically to comfort pin 625. This resistance circuit 650 comprises a chain or series connection of electrical resistances 651, 652, 653, 654, 655, and a number of comfort switches 656, 657, 658, 659, which can short-circuit various parts of the resistance circuit. Thus, in the example in Fig. 6, the switch 656 can short-circuit the series connection of resistances 652, 653, 654 and 655 so that only resistance 651 is still connected, from the standpoint of the wall module 601; the switch 657 short-circuits the series connection of resistances 653, 654 and 655 so that only the series connection of resistance 651 and 652 still remains connected, from the standpoint of the wall module 601; the switch 658 short-circuits the series connection of resistances 654 and 655 so that only the series connection of resistances 651, 652 and 653 still remains connected, from the standpoint of the wall module 601; and the switch 659 short-circuits the resistance 655 so that only the series connection of resistances 651, 652, 653 and 654 still remains connected, from the standpoint of the wall module 601. The switches 656, 657, 658 and 659 correspond to control buttons for comfort functions in the room of the person requiring care. These switches correspond for example to the control buttons 113 of the call button 101 from Fig. 1, and are used respectively for lowering the sunblind, raising the sunblind, switching the bed light on/off, and switching the room lighting on/off. The wall module 601 comprises a switchable supply 610 (of 24V) that is connected via an electrical resistance 612 to line pin contact 681. The electrical resistance 612 can be short-circuited by a switch 611 that is controlled by logic 616, for example a microprocessor, in the wall module 601. The logic 616 is connected to the call pin contact 683 and the detection pin contact 684 so that the logic 616 receives the call signal coming from normally closed call switch 641 and the detection signal coming from normally open detection switch 642, can interpret these signals, and based on these signals can control the switch 611. The electrical resistance 612 is dimensioned so that with switch 611 open, a limited electric current is sent through line pin 621. This current is shared in the call button 603 between the reassurance lamp 631-634 and the orientation lamp 635 so that both light up softly. As soon as the logic 616 detects the call signal coming from normally closed switch 641 or the detection signal coming from normally open switch 642, the wall module 601 will send an alarm signal to a central management system to which it is connected, or - in a simpler care call system - to an alarm lamp that is connected, for example in the corridor of a healthcare institution at the level of the room of the person requiring care. The switch 611 will also be closed, optionally after communication with the central management system. As a result, electrical resistance 612 is short-circuited and the electric current through line pin 621 is increased. The electrical resistance 636, interacting with the relatively constant voltage across the reassurance lamp 631-634, prevents the increase in current passing through the orientation lamp 635. The whole increase in current thus goes through the reassurance lamp 631-634 in call button 603, which will now light up brightly to confirm to the person requiring care that a care call has been sent. The logic 616 is, moreover, also connected to the output of a sensor 615, which measures the electric current through comfort pin contact 685 directly or indirectly. This electric current may for example be measured by connecting a power source/current limiter or voltage source 613 via an electrical resistance 614 to comfort pin contact 685 and measuring the voltage drop across the electrical resistance 614. The electric current that will be measured will depend on the electrical resistance that is seen from the wall module 601 on comfort pin 625, and thus change in each case when one of the comfort switches 656-659 is pressed. The measured level of the electric current is transmitted to the logic 616, which will interpret the signal received, can derive from that which comfort switch has been pressed, and will operate the corresponding function in the room. Owing to the presence of the resistance 655, the signal that is received from sensor 615 can also be used for detecting that the call button 603 has been pulled out or has come loose. An electric current will always be measured through comfort pin contact 685 if the call button 603 is connected correctly. As soon as an electric current is no longer measured, the logic 616 knows that call button 603 has been pulled out and an alarm signal can be sent to a person responsible for maintenance or a care provider so that it can be verified that the call button had been pulled out and the plug 602 can be fitted back in the negative plug correctly. According to the embodiment illustrated in Fig. 6, a very reliable care call system is thus realized that fulfils the basic functions of care call, reassurance lamp and orientation lamp, supports operation of a number of comfort functions and comprises pull-out detection, whereas the cable and plug that are used for connecting the call button 603 to the wall module 601 can be produced very cost-effectively: only 5 electrical wire conductors and only 5 contact pins are required.

[0054] Fig. 7A and 7B show a wall module 701 in a third embodiment of the care call system according to the invention wherein a 6-wire cable is sufficient for connecting either a call button 703 via a call button plug 702, or a monitoring appliance 707 via a monitor plug 702' to the same negative plug 708 in wall module 701. The cable itself is not shown in Fig. 7A but is thus located between the call button 703 and the plug 702. The cable 706 is shown in Fig. 7B. The 6-wire cable 706 with plug 702' is a special monitor cable with monitor plug, which is only used for connecting a monitoring appliance 707 to the wall module 701. The plug 702 comprises five contact pins 721, 722, 723, 724 and 725, which are connected to five pin contacts 781, 782, 783, 784 and 785 of the negative plug 708 with which wall module 701 is equipped. Contact pin 722 and the corresponding pin contact 782 are the electrical earth, respectively on the side of the call button 703 and the side of the wall module 701. Contact pin 721 is the line pin or control pin. Between the line pin 721 and the earth pin 722, the call button 703 comprises a power source 737 and the parallel connection of on the one hand a reassurance lamp 731-734 and on the other hand the series connection of an orientation lamp 735 and electrical resistance 736. The reassurance lamp is realized with 4 red LEDs, 731, 732, 733 and 734. The orientation lamp is realized with 1 white LED 735. The call button 703 further comprises a normally closed switch 741 between the so-called call pin 723 and the earth pin 722, and a normally open switch 742 between the so-called detection pin 724 and the earth pin 722. The normally closed switch 741 and normally open switch 742 form part of the call actuator of the call button 703, and correspond for example to the switches 203 and 204 of the call actuator 111 illustrated in Fig. 2. The call button 703 further comprises a resistance circuit 750 that is connected electrically to comfort pin 725. This resistance circuit 750 comprises a chain or series connection of electrical resistances 751, 752, 753, 754, 755, and a number of comfort switches 756, 757, 758, 759, which can short-circuit various parts of the resistance circuit. Thus, in the example in Fig. 7A, the switch 756 can short-circuit the series connection of resistances 752, 753, 754 and 755 so that only resistance 751 still remains connected, from the standpoint of the wall module 701; the switch 757 short-circuits the series connection of resistances 753, 754 and 755 so that only the series connection of resistance 751 and 752 still remains connected, from the standpoint of the wall module 701; the switch 758 short-circuits the series connection of resistances 754 and 755 so that only the series connection of resistances 751, 752 and 753 still remains connected, from the standpoint of the wall module 701; and the switch 759 short-circuits the resistance 755 so that only the series connection of resistances 751, 752, 753 and 754 still remains connected, from the standpoint of the wall module 701. The switches 756, 757, 758 and 759 correspond to control buttons for comfort functions in the room of the person requiring care. These switches correspond for example to the control buttons 113 of the call button 101 from Fig. 1, and are used respectively for lowering the sunblind, raising the sunblind, switching the bed light on/off, and switching the room lighting on/off. The wall module 701 comprises a switchable supply 710 (of 24V) that is connected via an electrical resistance 712 to line pin contact 781. The electrical resistance 712 can be short-circuited by a switch 711 that is controlled by logic 716, for example a microprocessor, in the wall module 701. The logic 716 is connected to the call pin contact 783 and the detection pin contact 784 so that the logic 716 receives the call signal coming from normally closed call switch 741 and the detection signal coming from normally open detection switch 742, can interpret these signals, and based on these signals can control the switch 711. The electrical resistance 712 is dimensioned so that with switch 711 open, a limited electric current is sent through line pin 721. This current is shared in the call button 703 between the reassurance lamp 731-734 and the orientation lamp 735 so that both light up softly. As soon as the logic 716 detects the call signal coming from normally closed switch 741 or the detection signal coming from normally open switch 742, the wall module 701 will send an alarm signal to a central management system to which it is connected, or - in a simpler care call system - to an alarm lamp that is installed for example in the corridor of a healthcare institution at the level of the room of the person requiring care. The switch 711 will also be closed, optionally after communication with the central management system. As a result, electrical resistance 712 is short-circuited and the electric current through line pin 721 is increased. The electrical resistance 736, interacting with the relatively constant voltage across reassurance lamp 731-734, prevents the increase in current passing through the orientation lamp 735. The whole increase in current thus goes through the reassurance lamp 731-734 in call button 703, which will now light up brightly to confirm to the person requiring care that a care call has been sent. The logic 716 is, moreover, also connected to the output of a sensor 715, which measures the electric current through comfort pin contact 785 directly or indirectly. This electric current may for example be measured by connecting a power source or voltage source 713 via an electrical resistance 714 to comfort pin contact 785 and measuring the voltage drop across the electrical resistance 714. The electric current that will be measured will depend on the electrical resistance which, seen from the wall module 701, is on comfort pin 725, and thus change whenever one of the comfort switches 756-759 is pressed. The measured level of the electric current is transmitted to the logic 716, which will interpret the signal received, can derive from that which comfort switch has been pressed, and will operate the corresponding function in the room. Owing to the presence of the resistance 755, the signal that is received from sensor 715, may also be used for detecting that the call button 703 has been pulled out or has come loose. An electric current will always be measured through comfort pin contact 785 if the call button 703 is connected correctly. As soon as an electric current is no longer measured, the logic 716 knows that call button 703 has been pulled out and an alarm signal can be sent to a person responsible for maintenance or a care provider so that it can be verified that the call button had been pulled out and the plug 702 can be reinserted correctly in the negative plug.

[0055] The negative plug 708 in wall module 701 further comprises a sixth pin contact, namely monitor pin contact 786, connected to logic 716. The call button cable with call button plug 702 may be configured with 5 electrical conductors and 5 contact pins 721-725, or with 6 electrical conductors and 6 electrical contact pins. In the last case the sixth electrical conductor is connected to the sixth contact pin (which is then inserted in monitor pin contact 786) but in the call button 703 there is no component that is connected to the sixth electrical conductor and sixth contact pin. In other words the sixth electrical conductor and the sixth contact pin remain unused but they make it possible to distinguish from the situation wherein a monitoring appliance is coupled to the same negative plug 708 in the same wall module 701 instead of a call button, as described below.

[0056] In Fig. 7B, a monitoring appliance 707 is now connected to the negative plug 708 of wall module 701, where in Fig. 7A call button 703 was coupled. The monitoring appliance 707 is connected via a monitor cable 706 to monitor plug 702'. This monitor cable 706 comprises six electrical conductors, and the monitor plug 702' comprises six contact pins, 721', 722', 723', 724', 725' and 726'. The five contact pins 721', 722', 723', 724' and 725' correspond to the contact pins 721, 722, 723, 724 and 725 of the call button plug 702 from Fig. 7A. The contact pins 721' (line pin), 723' (call pin) and 724' (detection pin) remain unused. The sixth contact pin 726' provides contact with the monitor pin contact 786 of the negative plug 708, and is also connected via the sixth electrical conductor from cable 706 to a switch 771 in the monitoring appliance 707. If this switch were to be a normally closed switch, logic 716 would be able to distinguish from the situation from Fig. 7A wherein a call button is connected, because the normally closed switch would allow detection of the monitoring appliance on monitor pin contact 786. Fig. 7B shows the situation wherein switch 771 is a normally open switch, so that logic 716 is unable, purely on the basis of the signal on monitor pin contact 786, to distinguish from the situation from Fig. 7A where a call button is connected. For this reason, use is made of a special monitor cable 706, which comprises an electrical resistance 761 between the electrical conductors that are connected to the earth pin 722' and the comfort pin 725'. The resistance 761 has a resistance value that differs from each resistance value that can be produced by the resistance circuit 750 (by switching parts thereof on or off). A person skilled in the art will understand that in an alternative embodiment resistance 761 may form part of the monitor plug 702' instead of forming part of the monitor cable 706. The logic 716 can, besides the resistance levels that can be produced by resistance circuit 750, distinguish an extra resistance level, namely the resistance value of resistance 761. If this resistance value is detected (directly or indirectly by sensor 715), the logic 716 will conclude that a monitoring appliance 707 has been connected, for example an infusion pump, a mattress detector, a heartbeat monitor, an apparatus with baby alarm function, etc. Said monitoring appliance 707 will be able to transmit an alarm signal to the wall module 701 of the care call system via monitor pin contact 786, which will be received and interpreted by logic 716, after which a care call can be sent to a central management system or a care provider. The resistance measurement also allows a special monitor pull-out protection call to be generated if the monitor cable is pulled out.

[0057] According to the embodiment illustrated in Fig. 7A and Fig. 7B, a very reliable care call system is thus realized, which on connecting a call button fulfils the basic functions of care call, reassurance lamp and orientation lamp, supports operation of a number of comfort functions and comprises pull-out detection, and on connecting a monitoring appliance, detects that a monitoring appliance has been connected and transmits alarm signals from the monitoring appliance, while the cables and plugs that are used for connecting the call button 703 and monitoring appliance 707 to the wall module 701 can be produced very cost-effectively: only 6 electrical wire conductors and only 6 contact pins are required.

[0058] Fig. 8A, 8B, 8C and 8D show a wall module 801 in a third embodiment of the care call system according to the invention wherein a 6-wire cable is sufficient for connecting either a call button 803 via a call button plug 802, or a monitoring appliance 807 via a monitor plug 802', or a digital handset 809 via a handset plug 802", or a simple digital handset 809' via a simple handset plug 802‴ to the same negative plug 808 in wall module 801. The cable itself is not shown in Fig. 8A but is thus located between the call button 803 and the plug 802. The cable 806 is shown in Fig. 8B. The 6-wire cable 806 with plug 802' is a monitor cable with special monitor plug 802', which is only used for connecting a monitoring appliance 807 to the wall module 801. Also in Fig. 8C, use is made of a cable with special plug 802", this time called handset plug, just as in Fig. 8D where a cable with special plug 802‴ is also used, namely the simple handset plug.

[0059] The plug 802 comprises five contact pins 821, 822, 823, 824 and 825, which are connected to five pin contacts 881, 882, 883, 884 and 885 of the negative plug 808 with which wall module 801 is equipped. This negative plug 808 additionally comprises five other pin contacts, 886, 887, 888, 889 and 890, which will be used for connecting a monitoring appliance, a digital handset or a simple digital handset. Contact pin 822 and the corresponding pin contact 882 are connected to each other and form the earth pin and earth pin contact, on the side of the call button 803 and on the side of the wall module 801, respectively. Contact pin 821 is the control pin. Between the control pin 821 and the earth pin 822, the call button 803 comprises a power source 837 and the parallel connection of on the one hand a reassurance lamp 831-834 and on the other hand the series connection of an orientation lamp 835 and electrical resistance 836. The reassurance lamp is realized with 4 red LEDs, 831, 832, 833 and 834. The orientation lamp is realized with 1 white LED 835. The call button 803 further comprises a normally closed switch 841 between the so-called call pin 823 and the earth pin 822, and a normally open switch 842 between the so-called detection pin 824 and the earth pin 822. The normally closed switch 841 and normally open switch 842 form part of the call actuator of the call button 803, and correspond for example to the switches 203 and 204 of the call actuator 111 illustrated in Fig. 2. The call button 803 further comprises a resistance circuit 850 that is connected electrically to comfort pin 825. This resistance circuit 850 comprises a chain or series connection of electrical resistances 851, 852, 853, 854, 855, and a number of comfort switches 856, 857, 858, 859, which can short-circuit various parts of the resistance circuit. Thus, in the example in Fig. 8A, the switch 856 can short-circuit the series connection of resistances 852, 853, 854 and 855 so that only resistance 851 still remains connected, from the standpoint of the wall module 801; the switch 857 short-circuits the series connection of resistances 853, 854 and 855 so that only the series connection of resistance 851 and 852 still remains connected, from the standpoint of the wall module 801; the switch 858 short-circuits the series connection of resistances 854 and 855 so that only the series connection of resistances 851, 852 and 853 still remains connected, from the standpoint of the wall module 801; and the switch 859 short-circuits the resistance 855 so that only the series connection of resistances 851, 852, 853 and 854 still remains connected, from the standpoint of the wall module 801. The switches 856, 857, 858 and 859 correspond to control buttons for comfort functions in the room of the person requiring care. These switches correspond for example to the control buttons 113 of the call button 101 from Fig. 1, and are used respectively for lowering the sunblind, raising the sunblind, switching the bed light on/off, and switching the room lighting on/off. The wall module 801 comprises a switchable supply 810 (of 24V) that is connected via an electrical resistance 812 to the centre tap of a first LVDS transformer 819 of LVDS transmitter/receiver 818. The LVDS transmitter/receiver 818 is further equipped with a second transformer 820. The first LVDS transformer 819 has a first contact connected to control pin contact 881 and a second contact connected to the ninth pin contact 889. The centre tap is thus connected to the switchable supply 810. The second LVDS transformer 820 has a first contact connected to earth pin contact 882 and a second contact connected to the tenth pin contact 890. The centre tap of the second LVDS transformer 820 is connected to the electrical earth. Besides the LVDS transmitter/receiver 818, the wall module 801 is also equipped with a CAN bus 817 connected to the seventh pin contact 887 and eighth pin contact 888. The electrical resistance 812 can be short-circuited by a switch 811 that is controlled by logic 816, for example a microprocessor, in the wall module 801. The logic 816 is connected to the call pin contact 883 and the detection pin contact 884 so that the logic 816 receives the call signal coming from normally closed call switch 841 and the detection signal coming from normally open detection switch 842, can interpret these signals, and based on these signals can control the switch 811. The electrical resistance 812 is dimensioned so that with switch 811 open, a limited electric current is sent through control pin 821. This current is shared in the call button 803 between the reassurance lamp 831-834 and the orientation lamp 835, so that both light up softly. As soon as the logic 816 detects the call signal coming from normally closed switch 841 or the detection signal coming from normally open switch 842, the wall module 801 will send an alarm signal to a central management system to which it is connected, or - in a simpler care call system - to an alarm lamp that is installed for example in the corridor of a healthcare institution at the level of the room of the person requiring care. The switch 811 will also be closed. As a result, electrical resistance 812 is short-circuited and increases the electric current through control pin 821. The electrical resistance 836, interacting with the relatively constant voltage across the reassurance lamp 831-834, prevents the increase in current passing through the orientation lamp 835. The whole increase in current thus goes through the reassurance lamp 831-834 in call button 803, which will now light up brightly to confirm to the person requiring care that a care call has been sent. The logic 816 is, moreover, also connected to the output of a sensor 815, which measures the electric current through or voltage on comfort pin contact 885 directly or indirectly. This electric current may for example be measured by connecting a power source/current limiter or voltage source 813 via an electrical resistance 814 to comfort pin contact 885 and measuring the voltage drop across the electrical resistance 814. The electric current that will be measured will depend on the electrical resistance that is seen from the wall module 801 on comfort pin 825, and thus change whenever one of the comfort switches 856-859 is pressed. The measured level of the electric current is transmitted to the logic 816, which will interpret the signal received, can derive from that which comfort switch has been pressed, and will operate the corresponding function in the room. Owing to the presence of the resistance 855, the signal that is received from sensor 815 may also be used to detect that the call button 803 has been pulled out or has come loose. An electric current will always be measured through comfort pin contact 885 if the call button 803 is connected correctly. As soon as an electric current is no longer measured, the logic 816 knows that call button 803 has been pulled out and an alarm signal can be sent to a person responsible for maintenance or a care provider so that it can be verified that the call button had been pulled out and the plug 802 can be reinserted correctly in the negative plug 808.

[0060] The negative plug 808 in wall module 801 comprises a sixth pin contact, namely monitor pin contact 886, connected to logic 816. The call button cable with call button plug 802 may be configured with 5 electrical conductors and 5 contact pins 821-825, or with 6 electrical conductors and 6 electrical contact pins. In the last case, the sixth electrical conductor is connected to the sixth contact pin (which is then inserted in monitor pin contact 886) but in the call button 803 there is no component that is connected to the sixth electrical conductor and sixth contact pin. In other words, the sixth electrical conductor and the sixth contact pin remain unused but they make it possible to distinguish from the situation where a monitoring appliance is coupled to the same negative plug 808 in the same wall module 801 instead of a call button, as described below.

[0061] In Fig. 8B, a monitoring appliance 807 is now connected to the negative plug 808 of wall module 801, where in Fig. 8A call button 803 was coupled. The monitoring appliance 807 is connected via a cable 806 to monitor plug 802'. This cable 806 comprises six electrical conductors, and the monitor plug 802' comprises six contact pins, 821', 822', 823', 824', 825' and 826'. The five contact pins 821', 822', 823', 824' and 825' correspond to the contact pins 821, 822, 823, 824 and 825 of the call button plug 802 from Fig. 8A. The contact pins 821' (control pin), 823' (call pin) and 824' (detection pin) remain unused. The sixth contact pin 826' provides contact with monitor pin contact 886 of the negative plug 808, and is further connected via the sixth electrical conductor from cable 806 to a switch 871 in the monitoring appliance 807. If this switch were to be a normally closed switch, logic 816 would be able to distinguish from the situation from Fig. 8A wherein a call button is connected, because the normally closed switch would allow detection of the monitoring appliance 807 on monitor pin contact 886. Fig. 8B shows the situation wherein switch 871 is a normally open switch so that logic 816 is unable, solely on the basis of the signal on monitor pin contact 886, to distinguish from the situation from Fig. 8A where a call button is connected. For this reason, use is made of a special monitor cable 806 that comprises an electrical resistance 861 between the electrical conductors that are connected to the earth pin 822' and the comfort pin 825'. The resistance 861 has a resistance value that differs from each resistance value that can be produced by the resistance circuit 850 (by switching parts thereof on or off). A person skilled in the art will understand that in an alternative embodiment, resistance 861 may form part of the monitor plug 802' instead of forming part of the monitor cable 806. The logic 816 may, besides the resistance levels that can be produced by resistance circuit 850, distinguish an extra resistance level, namely the resistance value of resistance 861. If this resistance value is detected (directly or indirectly by sensor 815), the logic 816 will conclude that a monitoring appliance 807 has been connected, for example an infusion pump, a mattress detector, a heartbeat monitor, an apparatus with baby alarm function, etc. This monitoring appliance 807 will be able to transmit an alarm signal to the wall module 801 of the care call system via monitor pin contact 886, which will be received and interpreted by logic 816, after which a call may be sent to a central management system or a care provider. The resistance measurement also allows a special monitoring pull-out protection call to be generated if the monitor cable is pulled out.

[0062] In Fig. 8C, a digital handset 809 is now connected to the negative plug 808 of wall module 801, where in Fig. 8A, call button 803 was coupled. The digital handset 809 is connected via a 6-wire cable to digital handset plug 802". This digital handset plug 802" comprises six contact pins, 821", 822", 827", 828", 829" and 830". The two contact pins 821" and 822" correspond to the contact pins 821 and 822 of the call button plug 802 from Fig. 8A. The digital handset 809 comprises a call actuator with at least one normally closed switch 841' and at least one normally open switch 842', and a number of control buttons for comfort functions which are represented in Fig. 8C by the switches 856', 857', 858' and 859'. The digital handset 809 further comprises a microcontroller 895, which receives and interprets the signals coming from the actuator switches 841'-842' and comfort switches 856'-859'. The digital handset 809 further comprises a reassurance lamp, which in Fig. 8C is represented by power source 837' and LEDs 831', 832', 833' and 834'. Microcontroller 895 controls the reassurance lamp 831'-834', 837' on the basis of the signals received from the actuator switches 841'-842'. The digital handset also comprises an orientation lamp, which in Fig. 8C is represented by LED 835' and resistance 836'. The digital handset 809 has its own supply, which is used among other things for the reassurance lamp and the orientation lamp. The digital handset 809 further comprises a Controller Area Network bus physical layer 891 connected to a seventh contact pin 827" and eighth contact pin 828" in digital handset plug 802", and an audio/video transmitter/receiver 892 with a first transformer 893 and a second transformer 894. The first transformer 893 has a first contact connected to control pin contact 821" and a second contact connected to the ninth contact pin 829". The centre tap of the first transformer 893 is connected to the supply (24V) in the digital handset 809. The second transformer 894 has a first contact connected to the earth pin 822" and a second contact connected to the tenth contact pin 830" of the digital handset plug 802". The centre tap of the second transformer 894 is connected to the electrical earth. The digital handset plug 802" thus comprises six contact pins: line pin 821", earth pin 822", the seventh contact pin 827", the eighth contact pin 828", the ninth contact pin 829" and the tenth contact pin 830", and may thus be connected via a 6-wire cable to the digital handset 809. The wall module 801 comprises, as described above, a Controller Area Network bus 817, abbreviated to CAN bus, and a Low-Voltage Differential Signal transmitter/receiver 818, abbreviated to LVDS transmitter/receiver, with two transformers 819 and 820. The negative plug 808 that forms part of the wall module 801 comprises two CAN pin contacts 887 and 888, to which the CAN bus 817 is coupled electrically. The first LVDS transformer 819 has a first contact connected to control pin contact 881 and a second contact connected to the ninth pin contact 889. The centre tap is connected to the switchable supply 810. The second LVDS transformer 820 has a first contact connected to earth pin contact 882 and a second contact connected to the tenth pin contact 890. The centre tap of the second LVDS transformer 820 is connected to the electrical earth. A particular feature is that two of the four pin contacts that are used for connection of the LVDS transformers, namely 881 and 882, are the control pin and earth pin respectively of the negative plug 808, and so are also used when a call button is connected to the wall module. The digital handset 809 allows a care call to be sent but is, moreover, a more complex apparatus that also supports functions such as telephony, intercom, music in the room, video communication, etc. For this purpose the digital handset 809 is equipped with a CAN bus physical layer 891 and an LVDS transmitter/receiver 892, and will typically also be equipped with more advanced user interfaces such as a screen, a keyboard, a touchscreen, etc. The CAN bus technology 817, 891 is a digital 2-wire connection between digital handset 809 and wall module 801 that is used for the call function and the reassurance lamp. The LVDS technology 818, 892 requires 4 contacts between plug and negative plug for two transformers, which make the transmission of an audio signal and video signal possible.

[0063] In Fig. 8D, a simple digital handset 809' is now connected to the negative plug 808 of wall module 801, where in Fig. 8A, call button 803 was coupled. The simple digital handset 809' may also be connected via a 6-wire cable, of which only 5 wires are used, and a simple handset plug 802'". This simple handset plug 802‴ comprises five contact pins, 821'", 822'", 825'", 827‴ and 828". The two contact pins 821‴ and 822‴ correspond to the contact pins 821 and 822 of the call button plug 802 from Fig. 8A. The simple digital handset 809' comprises a user interface 896 (including an actuator with normally closed and normally open switches), optionally a number of lamps 897 (including an orientation lamp and reassurance lamp), and a microcontroller 895', which receives and interprets the signals coming from the user interface 896 and optionally operates the lamps 897. The microcontroller 895' is equipped with a serial data output 898 that is connected via a serial driver 899 to the comfort pin 825‴ in the simple handset plug 802'". In this way, the microcontroller 895' can send a unique identification for the simple digital handset 809' to wall module 801. The unique identification will be transmitted via the sensor 815, which measures changes in current through comfort pin contact 885, to a serial data input 8162 of the logic 816 in the wall module 801. The logic 816 in the wall module 801 is able to distinguish reception of a unique identification code coming from a simple digital handset 809' from resistance detection if a call button or monitoring appliance is connected. The digital handset 809' further comprises a Controller Area Network bus physical layer 891' connected to a seventh contact pin 827‴ and eighth contact pin 828‴ in the simple handset plug 802'". The simple handset plug 802‴ thus comprises five contact pins: line pin 821‴, earth pin 822'", comfort pin 825'", the seventh contact pin 827", the eighth contact pin 828", and may thus also be connected via a 5-wire cable or a 6-wire cable, wherein one wire remains unused, to the simple digital handset 809'. The simple digital handset 809' allows a care call to be sent. The CAN bus technology 817, 891' is a digital 2-wire connection between the simple digital handset 809' and wall module 801 that is used for the call function and the reassurance lamp. The simple digital handset 809' does not support any audio/video communication.

[0064] According to the embodiment illustrated in Fig. 8A, Fig. 8B, Fig. 8C and Fig. 8D, a very reliable care call system is thus realized, which on connecting a call button, fulfils the basic functions of care call, reassurance lamp and orientation lamp, supports operation of a number of comfort functions and comprises pull-out detection, on connecting a monitoring appliance detects that a monitoring appliance has been connected and transmits alarm signals from the monitoring appliance, on connecting a digital handset also supports audio/video communication, and on connecting a simple digital handset also supports the basic functions without audio/video communication, while the cables and plugs that are used for connecting the call button 803, monitoring appliance 807, the digital handset 809 or the simple digital handset 809' to the wall module 801 can be produced very cost-effectively: only 6 electrical wire conductors are required, since each of the plugs has at most 6 contact pins. An identical 6-wire cable may thus be used for connecting all appliances to the wall module 801.

[0065] Fig. 10 and Fig. 11A-11C illustrate embodiments of the present invention that make predictive maintenance possible. In these embodiments, wear of components is monitored so that timely intervention is possible, for example by replacing the wear-sensitive components before they fail, or by replacing a complete apparatus before it fails. This predictive maintenance is particularly advantageous when use is made of wear-sensitive technology, for example such as carbon contacts, which could be used for making the normally closed switches described above. However, the use of two different technologies, more specifically the combination of normally closed switches with normally open switches as required in the present invention, allows the wear or reliability of components to be tracked over time so that maintenance or replacement becomes possible and the system will thus still meet the reliability requirements. Fig. 10 shows, for example, a part 1001 of a room module, to which a call button 1003 is connected via cable 1002. In the call button 1003, the normally open switch 1042 is made with a (wear-susceptible) carbon contact with a contact resistance RcNO. In the room module 1001, 1011 represents the pull-up resistance that ensures that the DC voltage of 5 V is applied on the input of the gate / comparator 1015 at the input of microcontroller 1016. The pull-up resistance 1011 is assumed to have a resistance value R1NO. Moreover, the signal is conditioned on the basis of a filter. The capacitors 1012, 1014 and resistance 1013 form a so-called EMC Pi-filter 1010 (Electromagnetic Compliance filter with Pi-form). Resistance 1013 has a resistance value R2D, capacitor 1012 has a capacitance value C1NO and capacitor 1014 has a capacitance value C2NO, wherein it may be assumed that C1D is negligibly small compared to C2NO, in order to limit the switch-on current through switch 1042. On pressing the detection actuator, switch 1042 is closed and capacitor 1014 is discharged via the contact resistance RcNO and resistance 1013. This occurs with a time constant that is approximately equal to (R2NO+RcNO).C2NO (time constant at the level of 1113). On releasing the detection actuator, switch 1042 is opened and capacitor 1014 is charged via the resistances 1011 and 1013. This occurs with a time constant that is approximately equal to (R1NO+R2NO).C2NO (time constant at the level of 1114), and which is thus independent of the contact resistance RcD of switch 1042. It is thus a matter of finding the signal before the gate / comparator 1015. The foregoing also applies of course to the normally closed switch, present in call button 1003 but not drawn in Fig. 10. The call signal before the gate will then be determined by the RC time constants (R2NC+RcNC).C2NC (time constant at the level of 1112) and (R2NC+R1NC).C2NC (time constant at the level of 1111). By measuring the decay time of the signal after the PI filter, it is possible in principle to determine the contact resistance Rc, both for the NO-contact and the NC-contact. The decay time can be measured by a direct analogue measurement provided the necessary hardware is added, such as one or more analogue/digital converters. In a preferred embodiment, however, the switching time points are observed after the gate / comparator 1015, both for the signal coming from the normally open contact and for the signal coming from the normally closed contact. This is illustrated in Fig. 11A. This shows the switching time points of the normally closed switch (CALL or 1110) and the switching time points of the normally open switch (DETECT or 1120).

[0066] Fig. 11B illustrates the conditioned signal from a normally closed call switch and normally open detection switch 1042 before the gate (1101', 1102') and after the gate (1101 and 1102), at a time when there is still no wear. The switching time points of the call switch and detection switch are shown at the top. The corresponding charge and discharge curve of the capacitor is represented by 1101' and 1102'. On opening the call switch, the capacitor is charged at about time point 1111 with a time constant (R1NC+R2NC).C2NC. On closing the call switch, the capacitor is discharged at about time point 1112 with a time constant (RcNC+R2NC).C2NC. Here, RcNC is the contact resistance of the call switch. Something similar occurs for the detection switch. The corresponding charge curve of the capacitor is represented by 1102'. On closing the switch 1042, the capacitor is discharged at about time point 1113 with a time constant (RcNO+R2NO).C2NO. Here, RcNO is the contact resistance of the detection switch. On opening the switch 1042, the capacitor is charged at about time point 1114 with a time constant (R1NO+R2NO).C2NO. On pressing the actuator, a time difference d1 is measured (in each case after the gate / comparator) between the switching time points of the conditioned signals of the normally closed switch and the normally open switch 1042. On releasing the actuator, a time difference d2 is measured between the switching time points of the conditioned signals of the normally closed switch and the normally open switch 1042. Fig. 11C illustrates what occurs when there is wear of the normally closed switch and wear of the normally open switch. The switching time points of the conditioned signal of the call switch after the gate / comparator are now shown in 1103. The corresponding charge curve of the capacitor is represented by 1103'. On opening the switch, the capacitor is still charged at about time point 1121 with a time constant (R1NC+R2NC).C2NC. On closing the switch, the capacitor is discharged at about time point 1122 with a time constant (RcNC+R2NC).C2NC that has become larger as a result of wear of the normally closed switch. The switching time points of the conditioned signal of the detection switch 1042 after the gate / comparator are shown in 1104. The corresponding charge curve of the capacitor is represented by 1104'. On closing the switch 1042, the capacitor is discharged at about time point 1123 with a time constant (RcNO+R2NO).C2NO that has become larger as a result of wear of the normally open switch. On opening the switch 1042, the capacitor is charged at about time point 1124 with a time constant (R1NO+R2NO).C2NO that has remained unchanged. On pressing the actuator, now another time difference d1' is measured between the switching time points of the conditioned signals of the normally closed switch and the normally open switch 1042. On releasing the actuator, another time difference d2' is also measured between the switching time points of the conditioned signals of the normally closed switch and normally open switch 1042. Through wear of the normally open switch 1042, the time difference d1 will thus decrease to D1' (in Fig. 11C, d1' is even negative). Through wear of the normally closed switch, the time difference d2 will decrease to d2' (in Fig. 11C, d2' is even negative). It is crucial for wear measurement that both a normally closed switch and a normally open switch are present. On pressing the call actuator, the time constant of one of the two conditioned signals (for example the detection signal) is dependent on the contact resistance, whereas the time constant of the other signal (for example the call signal) is independent of the contact resistance. The reverse then applies on releasing the call actuator. The wear of the contact resistances of both switches may be monitored either by measuring the relative course d1, d2 between the switching time points of both switches on pressing and releasing the actuator button, or by measuring the relative course of the difference of the length of the conditioned call pulse and the length of the conditioned detection pulse. As soon as certain thresholds are exceeded, preventive action may be taken, for example such as replacement of a switch. A person skilled in the art will understand that in the above reasoning it was assumed that the resistance of the wiring is negligible. The monitoring of wear as described above is independent of the duration of operation of the actuator and may still be applied if the call switch (at the time when there is still no wear) would open faster and would close later than the detection switch closes and opens.

[0067] It is noteworthy that in a preferred embodiment, the wall socket with negative plug is downward-compatible. That is, the wall socket that is suitable for the digital handset can also accept a monitor and care call button. The wall socket that is suitable for a monitor can also accept a call button, but not a digital handset. By mechanical keying, that will also be prevented. The wall socket that is suitable for a call button can only accept a call button. Again through mechanical keying, a digital handset and a monitor will not fit here mechanically.

[0068] Although the present invention has been illustrated on the basis of specific embodiments, it will be clear to a person skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention can be carried out with various changes and adjustments while remaining within the scope of the invention. The present embodiments must therefore be considered at all levels as illustrative and not restrictive, wherein the scope of the invention is described by the appended claims and not by the foregoing description, and all changes that fall within the meaning and the scope of the claims are consequently incorporated here. In other words it is assumed that this covers all changes, variations or equivalents that fall within the scope of the underlying basic principles and whose essential attributes are claimed in this patent application. In addition, the reader of this patent application will understand that the words "comprising" or "comprise" do not exclude other elements or steps, that the word "a" does not exclude the plural, and that a single element, such as a computer system, a processor or another integrated unit may fulfil the functions of various devices that are stated in the claims. Any references in the claims are not to be understood as a limitation of the claims in question. The terms "first", "second", "third", "a", "b", "c" and such, when used in the description or in the claims, are used in order to differentiate between similar elements or steps and do not necessarily describe a successive or chronological order. In the same way, the terms "upper side", "underside", "over", "under" and such are used for the purpose of the description and they do not necessarily refer to relative positions. It must be understood that these terms are mutually interchangeable in the right circumstances and that embodiments of the invention are able to function according to the present invention in other sequences or orientations than those described or illustrated in the foregoing.

Claims

1. Care call system comprising:

- a call button (101; 403; 503; 603; 703; 803);

- a cable (121; 404) with plug (131; 402; 502; 602; 702; 802), wherein said cable (121; 404) is connected to said call button (101; 403; 503; 603; 703; 803); and

- a wall module (141-143; 501; 601; 701; 801) with negative plug (151-155; 508; 608; 708; 808) for said plug (131; 402; 502; 602; 702; 802),

wherein said call button (101; 403; 503; 603; 703; 803) comprises a call actuator (111; 441-442; 541-542; 641-642; 741-742; 841-842) enabling a patient to call a care provider from a room,

CHARACTERIZED IN THAT said call actuator (111; 441-442; 541-542; 641-642; 741-742; 841-842) comprises at least one call switch (203; 441; 541; 641; 741; 841) and at least one detection switch (204; 442; 542; 642; 742; 842), the respective signals of which are transmitted via said cable (121; 404) with said plug (131; 402; 502; 602; 702; 802) to said wall module (141-143; 501; 601; 701; 801), and wherein said call actuator (111) comprises one or more normally closed switches (203; 441; 541; 641; 741; 841) as call switch and comprises one or more normally open switches (204; 442; 542; 642; 742; 842) as detection switch, or vice versa, such that said detection switch (204; 442; 542; 642; 742; 842) allows to detect that said call switch (203; 441; 541; 641; 741; 841) is faulty and, conversely, said call switch (203; 441; 541; 641; 741; 841) allows to detect that said detection switch (204; 442; 542; 642; 742; 842) is faulty;

wherein a normally closed switch (203; 441; 541; 641; 741; 841) in rest state makes a connection between two contacts, and breaks the connection when said call actuator (111) is pressed in; and

wherein a normally open switch (204; 442; 542; 642; 742; 842) in rest state does not make any connection between two contacts, but does when said call actuator (111) is pressed in.

2. Care call system according to one of the preceding claims, wherein said call actuator (111; 441-442; 541-542; 641-642; 741-742; 841-842) comprises one normally closed switch (203; 441; 541; 641; 741; 742), comprises several normally open switches (204; 442; 542; 642; 742), and comprises an actuator cap (206), and wherein said normally open switches (204; 442; 542; 642; 742; 842) are regularly spaced round said normally closed switch (203; 441; 541; 641; 741; 841) under said actuator cap (206), or vice versa.

3. Care call system according to one of the preceding claims, wherein:

- said call button (101; 403; 503; 603; 703; 803) further comprises a reassurance lamp (112; 301; 430; 531-534; 631-634; 731-734; 831-834), which is switched on in the case of a call and for this is connected electrically to a control pin (421; 521; 621; 721; 821) in said plug (131; 402; 502; 602; 702) which is also used as line pin;

- said wall module (501; 601; 701; 801) comprises a switchable supply (510; 610; 710; 810), coupled to the corresponding line pin contact (581; 681; 781; 881) in said negative plug (151-155; 508; 608; 708; 808), as well as the corresponding control pin contact for said reassurance lamp (112; 301; 430; 531-534; 631-634; 731-734; 831-834); and

- said switchable supply (510; 610; 710; 810) comprises the parallel connection of an electrical resistance (512; 612; 712; 812) or power source and a switch (511; 611; 711; 811), coupled to said control pin contact (581; 681; 781; 881), and said switch (511; 611; 711; 811) switches said reassurance lamp (112; 301; 430; 531-534; 631-634; 731-734; 831-834) on and off.

4. Care call system according to claim 3, wherein:

- said call button (101; 403; 503; 603; 703) further comprises an orientation lamp (535; 635; 735; 835) that stays on permanently and for this purpose has a parallel connection to said reassurance lamp (112; 301; 430; 531-534; 631-634; 731-734; 831-834), between said control pin (421; 521; 621; 721; 821) and an earth pin (422; 522; 622; 722; 822) of said plug (131; 402; 502; 602; 702; 802).

5. Care call system according to one of the preceding claims, wherein:

- said call button (101; 403; 603; 703; 803) further comprises one or more function buttons (113; 656-659; 756-759; 856-859) for operating respectively one or more comfort functions in said room, and wherein said call button (101; 403; 603; 703; 803) comprises a resistance circuit (450; 650; 750; 850) connected electrically to one pin in said plug, called comfort pin (424; 625; 725; 825);

- said wall module (141-143; 601; 701; 801) comprises an electrical currentmeter or voltmeter (613; 713; 813), coupled to the corresponding comfort pin contact (685; 785; 885) in said negative plug (151-155; 608; 708; 808); and

- said function buttons (113; 656-659; 756-759; 856-859) switch respective parts of said resistance circuit (450; 650; 750; 850) on or off.

6. Care call system according to claim 5, wherein said call system comprises a pull-out detection that is realized with an additional resistance (655; 755; 855) in said resistance circuit (450; 650; 750; 850).

7. Care call system according to claim 5 or 6, wherein:

- said wall module (601; 701; 801) comprises a sensor (615; 715; 815), which measures the electric current through or voltage on said comfort pin contact (685; 785; 885) directly or indirectly; and

- said wall module (601; 701; 801) comprises a processor (616; 716; 816), coupled to said sensor (615; 715; 815) and configured for determining, from the sensor measurement, which of said function buttons (113; 656-659; 756-759; 856-859) has been activated and/or for determining that said plug (131; 402; 602; 702; 802) has been separated electrically from said negative plug (151-155; 608; 708; 808).

8. Care call system according to claim 5 or 6, wherein:

- said wall module (601; 701; 801) comprises a duplicate resistance circuit with power source; and

- said wall module (601; 701; 801) comprises a comparator bench, which compares the voltage on said comfort pin contact (685; 785; 885) with voltage levels obtained from said duplicate resistance circuit in order to determine which of said function buttons (113; 656-659; 756-759; 856-859) has been activated and/or to determine that said plug (131; 402; 602; 702; 802) has been separated electrically from said negative plug (151-155; 608; 708; 808).

9. Care call system according to one of the preceding claims, wherein:

- said negative plug (151-155; 708; 808) comprises a monitor pin contact (786; 886); and

- said wall module (701; 801) comprises logic (716; 816) connected electrically to said monitor pin contact (786; 886) for detecting that a monitoring appliance (707; 807) has been coupled to said negative plug (151-155; 708; 808) and/or for detecting that an alarm has come on for a monitoring appliance (707; 807) coupled to said negative plug (151-155; 708; 808).

10. Care call system according to claim 5 and claim 9, wherein:

- said logic (716; 816) forms part of said processor and said sensor (715, 815) is able to distinguish an additional electric current level through said comfort pin contact (785; 885) when said monitoring appliance (707; 807) is connected via a special monitor cable (706; 806) and special monitor plug (702'; 802') to a monitor negative plug (708) in said wall module (701; 801), wherein said monitor cable (706; 806) or said monitor plug (702'; 802') comprises an identification resistance (761; 861) between comfort pin (725', 825') and earth pin (722'; 822') of said monitor plug (702'; 802').

11. Care call system according to one of the preceding claims, further comprising:

- a digital handset (103; 809) with a call actuator (114; 841'-842'), a user interface (116, 117; 856'-859'), and a microcontroller (895) and/or Field-Programmable Gate Array coupled to said call actuator (114; 841'-842') and said user interface (116, 117; 856'-859'); and

- a cable (123) with handset plug (133; 802"), wherein said cable (123) is connected to said digital handset (103; 809),

and wherein said wall module (801) comprises the following:

- a Controller Area Network bus (817), called CAN bus;

- a Low-Voltage Differential Signal transmitter/receiver (818), called LVDS transmitter/receiver;

- a handset negative plug (155; 808), which integrates said negative plug for said call button with two CAN pin contacts (887, 888) connected electrically to said CAN bus (817) and four LVDS pin contacts (881, 882, 889, 890) connected electrically to said LVDS transmitter/receiver (818) and wherein two of the four said LVDS pin contacts (881, 882) are also used respectively as line pin and earth pin for said call button (803) when coupled to said handset negative plug (155; 808).

12. Care call system according to claim 5, further comprising:

- a digital handset (809') with a call actuator, a user interface (896), and a microcontroller (895') and/or Field-Programmable Gate Array coupled to said user interface (896), wherein said microcontroller (895') is configured to send an identification code via a serial data output (898); and

- a cable with handset plug (802‴), wherein said cable is connected to said digital handset (809') in such a way that said serial data output (898) of said microcontroller (895') is connected to the comfort pin (825‴) of said handset plug (802‴),

and wherein said wall module (801) comprises the following:

- a Controller Area Network bus (817), called CAN bus;

- a handset negative plug (808), which integrates said negative plug for said call button with two CAN pin contacts (887, 888) connected electrically to said CAN bus (817);

and wherein said processor (816') in said handset negative plug (808) is configured to detect said identification code on a serial data input (8162).

13. Care call system according to one of the preceding claims, wherein said wall module comprises a low-pass filter and logic configured to measure the time difference (d1, d2) between the switching time point of the conditioned call signal coming from said call switch (203; 441; 541; 641; 741; 841) and the corresponding switching time point of the conditioned detection signal coming from said detection switch (204; 442; 542; 642; 742; 842) in order to detect wear based thereon.

14. Care call system according to claim 13, wherein said wall module comprises logic configured to measure the change in the time difference (d1, d2) between the switching time point of said conditioned call signal coming from said call switch (203; 441; 541; 641; 741; 841) and the corresponding switching time point of said conditioned detection signal coming from said detection switch (204; 442; 542; 642; 742; 842) in order to detect wear based thereon.

Drawing