SLAVE UNIT FOR AUTOMATIC FIRE ALARM SYSTEM AND AUTOMATIC FIRE ALARM SYSTEM USING SAME

Abstract

 Transmitting circuit (14) that is electrically connected to a pair of electrical wires (51, 52) to which a voltage is applied and draws an electric current in from the pair of electrical wires (51, 52) as a drawn current. Determiner (161) determines an operating state including two states that are a fire notification state in which an occurrence of a fire is reported and a coordination notification state in which another device is caused to operate in coordination. When the result of the determination by determiner (161) indicates the fire notification state, controller (162) generates a fire notification by adjusting the value of the drawn current to a predetermined fire notification level. Controller (162) is configured to, when the result of the determination by determiner (161) indicates the coordination notification state, generate a coordination notification by adjusting the value of the drawn current to a predetermined coordination notification level which is different from the fire notification level.

Description

[Technical Field]

[0001] The present invention generally relates to a slave unit for an automatic fire alarm system and the automatic fire alarm system using the slave unit, and more particularly relates to a slave unit for an automatic fire alarm system which is electrically connected to a master unit through a pair of electrical wires, and the automatic fire alarm system using the slave unit.

[Background Art]

[0002] There have been two types of automatic fire alarm systems (AFASs), namely, P-type (proprietary-type) and R-type (record-type) systems. Both the P-type automatic fire alarm system and the R-type automatic fire alarm system are configured to detect the occurrence a fire by a slave unit including a heat sensor, a smoke sensor, and a flame sensor, and report the occurrence of the fire from the slave unit to a master unit including a receiver.

[0003] In the P-type automatic fire alarm system, the slave unit reports the occurrence of a fire to the master unit including the receiver by electrically short-circuiting a pair of electrical wires. In the R-type automatic fire system, the slave unit reports the occurrence of a fire to the master unit via communication using a transmission signal that is transmitted through a transmission line. Generally, the R-type automatic fire alarm system is often used in a large building, and the P-type automatic fire alarm system is often used in a middle-sized or smaller building for reasons of easy installation and the like.

[0004] Examples of the automatic fire alarm system include a system having a function of coordination with another device such as a smoke blocker or ejector or an emergency broadcasting system. In this type of the automatic fire alarm system, a slave unit has a function of generating a coordination notification for causing another device to operate in coordination, and when a master unit receives the coordination notification from the slave unit, the master unit causes another device to operate in coordination. In the P-type automatic fire alarm system, the master unit is not capable of distinguishing, through a single line, the coordination notification from a fire notification that informs a user of the occurrence of a fire, and thus separate lines need to be provided for the coordination notification and for the fire notification.

[0005] For example, Patent Literature (PTL) 1 discloses a P-type automatic fire alarm system in which a plurality of fire sensors which are slave units are connected to a plurality of sensor lines led from a fire receiver which is a master unit. The automatic fire alarm system disclosed in PTL 1 is configured such that when a slave unit detects an abnormality of the slave unit itself, the slave unit outputs an abnormality detection signal having the same signal format as a fire signal which is to be output to the master unit when a fire is detected, for a predetermined period of time different from output time of the fire signal. When the master unit receives the abnormality detection signal, the master unit distinguishes this input from input of the fire signal by a difference between input time of this abnormality detection signal and that of the fire signal, and performs a predetermined alarm operation.

[Citation List]

[Patent Literature]

[0006] [PTL 1] Japanese Unexamined Patent Application Publication No. 2002-008154

[Summary of Invention]

[Technical Problem]

[0007] In the automatic fire alarm system disclosed in PTL 1, however, the master unit can merely distinguish between the fire signal and the abnormality detection signal received from the slave unit; the master unit is not capable of distinguishing the fire notification and the coordination notification from each other. This means that in the automatic fire alarm system disclosed in PTL 1, addition of the function of coordination with another device eventually causes the need for separate lines to be provided for the fire notification and for the coordination notification, resulting in a complicated system configuration.

[0008] The present invention has been made in light of the issues described above and is intended to provide a slave unit for an automatic fire alarm system with the simplest possible configuration that is capable of additionally including a function of coordination with another device even through this automatic fire alarm system is of the P type, and to provide the automatic fire alarm system using the slave unit.

[Solution to Problem]

[0009] A slave unit for an automatic fire alarm system according to an aspect of the present invention includes: a transmitting circuit that is electrically connected to a pair of electrical wires to which a voltage is applied and draws an electric current in from the pair of electrical wires as a drawn current; a determiner that determines an operating state including two states that are a fire notification state in which an occurrence of a fire is reported and a coordination notification state in which another device is caused to operate in coordination; and a controller that controls the transmitting circuit to adjust a value of the drawn current, wherein the controller is configured to, when a result of determination by the determiner indicates the fire notification state, generate a fire notification by adjusting the value of the drawn current to a fire notification level that is predetermined, and when the result of determination by the determiner indicates the coordination notification state, generate a coordination notification by adjusting the value of the drawn current to a coordination notification level that is predetermined and different from the fire notification level.

[0010] An automatic fire alarm system according to an aspect of the present invention includes: the slave unit described above; and a master unit that applies a voltage between the pair of electrical wires.

[Advantageous Effects of Invention]

[0011] The present invention has the advantage of allowing even the P-type system to have the simplest possible configuration and additionally include a function of coordination with another device.

[Brief Description of Drawings]

[0012] 

[FIG. 1] FIG. 1 illustrates a schematic configuration of an automatic fire alarm system according to Embodiment 1.

[FIG. 2] FIG. 2 illustrates an overall configuration of an automatic fire alarm system according to Embodiment 1.

[FIG. 3] FIG. 3 is a schematic circuit diagram illustrating a slave unit for an automatic fire alarm system according to Embodiment 1.

[FIG. 4] FIG. 4 illustrates an operation of an automatic fire alarm system according to Embodiment 1.

[FIG. 5] FIG. 5 illustrates an operation of an automatic fire alarm system according to Embodiment 1.

[FIG. 6] FIG. 6 illustrates an operation of an automatic fire alarm system according to Embodiment 2.

[FIG. 7] FIG. 7 is a schematic circuit diagram illustrating a slave unit for an automatic fire alarm system according to Embodiment 3.

[Description of Embodiments]

Embodiment 1

[0013] Automatic fire alarm system 100 according to the present embodiment includes at least one slave unit 1 and one master unit 2, as illustrated in FIG. 1.

[0014] Master unit 2 includes voltage applicator 21 that applies a voltage between a pair of electrical wires 51 and 52.

[0015] Slave unit 1 includes transmitting circuit 14, determiner 161, and controller 162. Transmitting circuit 14 is electrically connected to a pair of electrical wires 51 and 52, to which a voltage is applied, and is configured to draw an electric current in from the pair of electrical wires 51 and 52 as a drawn current.

[0016]  Determiner 161 is configured to determine an operating state including two states that are a fire notification state in which the occurrence of a fire is reported and a coordination notification state in which another device 3 (see FIG. 2) is caused to operate in coordination. Controller 162 controls transmitting circuit 14 to adjust the value of the drawn current.

[0017] When the result of the determination by determiner 161 is the fire notification state, controller 162 generates the fire notification by adjusting the value of the drawn current to a predetermined fire notification level. Controller 162 is configured to generate, when the result of the determination by determiner 161 indicates the coordination notification state, the coordination notification by adjusting the value of the drawn current to a predetermined coordination notification level which is different from the fire notification level.

[0018] In other words, in slave unit 1 for automatic fire alarm system 100 according to the present embodiment, controller 162 generates the fire notification and the coordination notification by adjusting the value of the drawn current by controlling transmitting circuit 14 according to the result of the determination by determiner 161. To put it another way, slave unit 1 transmits an electric current signal that indicates the fire notification or the coordination notification in a distinguishable manner by switching the magnitude (the value) of an electric current that is drawn in (flows in) from a pair of electrical wires 51 and 52 between the fire notification level and the coordination notification level.

[0019] This allows master unit 2 for automatic fire alarm system 100 using this slave unit 1 to distinguish the fire notification and the coordination notification from each other without separating lines for the fire notification and for the coordination notification. Thus, slave unit 1 for automatic fire alarm system 100 according to the present embodiment has the advantage of allowing even the P-type system to have the simplest possible configuration and additionally include a function of coordination with another device 3.

[0020] Automatic fire alarm system 100 according to the present embodiment is described in detail below. The configurations described below are a mere example of the present invention, meaning that the present invention is not limited to the embodiments described below; various modifications can be made in the present invention according to the design and the like within the scope of the technical idea of the present invention to provide other embodiments.

Overall Configuration

[0021] In the present embodiment, automatic fire alarm system 100 used in a housing complex (condominium apartments) is described as an example; however, automatic fire alarm system 100 is applicable not only to a housing complex, but also to various buildings such as commercial facilities, hospitals, hotels, and multi-tenant buildings.

[0022] In automatic fire alarm system 100 according to the present embodiment, one master unit 2 and a plurality of slave units 101, 102, 103, ... are provided in one housing complex 6, as illustrated in FIG. 2. The plurality of slave units 101, 102, 103, ... are herein referred to simply as "slave unit 1" when these slave units are not particularly distinguished from one another.

[0023]  Furthermore, in this automatic fire alarm system 100, a pair of electrical wires 51 and 52 is provided on each of the first to the fourth floors. In other words, housing complex 6 includes four sets, in total, of paired electrical wires 51 and 52, which are two electrical wires forming one set (a two-wire system).

[0024] In this example, up to 40 to 80 slave units 1 can be connected to each set of electrical wires 51 and 52, and up to 50 to 200 lines (50 to 200 sets) of paired electrical wires 51 and 52 can be connected to one master unit 2. Thus, when up to 40 slave units 1 can be connected to each set of electrical wires 51 and 52 and up to 50 lines of paired electrical wires 51 and 52 can be connected to one master unit 2, for example, up to 2,000 (= 40 x 50) slave units 1 can be connected to one master unit 2. Note that these numerical values are one example; it is not intended that the present invention be limited to these numerical values.

[0025] Paired electrical wires 51 and 52 are electrically connected to each other via terminating resistor 4 at a terminating end of paired electrical wires 51 and 52 (which is an end opposite master unit 2). Master unit 2 is therefore capable of detecting disconnection of paired electrical wires 51 and 52 by monitoring an electric current flowing through paired electrical wires 51 and 52. Note that terminating resistor 4 is not an indispensable element; terminating resistor 4 may be omitted.

[0026] Automatic fire alarm system 100 is basically configured to detect the occurrence of a fire by slave unit 1 including a heat sensor, a smoke sensor, and a flame sensor, and report the occurrence of a fire (the fire notification) from slave unit 1 to master unit 2 which is a receiver. Slave unit 1 may include not only a sensor that detects the occurrence of a fire, but also a beacon or the like. The beacon is a device having a push-button switch (not illustrated in the drawings) and that when a person who discovers a fire manually operates the push-button switch, reports the occurrence of a fire (the fire notification) to master unit 2.

[0027] Automatic fire alarm system 100 has a coordination function of causing another device 3, such as a smoke blocker or ejector or an emergency broadcasting system, to operate in coordination when master unit 2 receives, from slave unit 1, a report for causing another device 3 to operate in coordination (the coordination notification). With this, at the occurrence of a fire, automatic fire alarm system 100 can, for example, control a fire door of the smoke blocker or ejector and output sound or voice from the emergency broadcasting system to inform a user of the occurrence of the fire.

[0028] Another device 3 is configured to be able to communicate with master unit 2 via, for example, wired communication, and is configured to operate in coordination with automatic fire alarm system 100 in response to an instruction from master unit 2. Another device 3 herein includes various devices such as smoke blocker and ejector, such as a fire door and a smoke ventilation system, an emergency broadcasting system, an external notification transfer device, and a fire extinguisher, such as a sprinkler; another device 3 herein is not limited to a particular device (system). The external notification transfer device reports a fire to an external related person, fire authority, security company, and the like.

[0029]  There are two types of general automatic fire alarm systems, P-type (proprietary-type) and R-type (record-type) systems. In the P-type automatic fire alarm system, a slave unit reports the occurrence of a fire to a master unit by electrically short-circuiting a pair of electrical wires. In the R-type automatic fire system, a slave unit reports the occurrence of a fire to a master unit via communication using a transmission signal that is transmitted through a transmission line.

[0030] Automatic fire alarm system 100 according to the present embodiment is basically of the P type. More specifically, in the case assumed in the present embodiment, in the housing complex in which the P-type automatic fire alarm system is provided, existing wiring (electrical wires 51 and 52) is used with a receiver replaced (by master unit 2) and slave units replaced (by slave unit 1). Note that automatic fire alarm system 100 according to the present embodiment can be applied as a newly introduced automatic fire alarm system.

[0031] In other words, by using slave unit 1 capable of adjusting the value of the drawn current (an electric current which transmitting circuit 14 draws in from a pair of electrical wires 51 and 52), automatic fire alarm system 100 according to the present embodiment additionally includes a function of the R-type system even through this automatic fire alarm system is of the P type. Specifically, in automatic fire alarm system 100, when a notification is issued, slave unit 1 adjusts the value of the drawn current to the fire notification level or the coordination notification level, so that master unit 2 can distinguish the fire notification and the coordination notification from each other. Thus, automatic fire alarm system 100 is capable of providing the function of the fire notification and the coordination function through a single line, resulting in having a reduced number of wires compared with the case where separate lines are provided for the fire notification and for the coordination notification.

[0032] Furthermore, in the present embodiment, slave unit 1 is configured to transmit a transmission signal representing transmission data, by varying the value of the drawn current between the first level and the second level. To put it another way, in the present embodiment, slave unit 1 is capable of communication using a transmission signal and thus is capable of transmitting data to master unit 2. Therefore, in automatic fire alarm system 100, when a notification is issued, for example, slave unit 1 transmits a preassigned identifier (address) to master unit 2, and thus master unit 2 is capable of identifying not a set of paired electrical wires 51 and 52, but slave unit 1, as the source that issues the notification. Furthermore, in automatic fire alarm system 100, while no notification is issued (in the normal situation), communication can be performed between master unit 2 and slave unit 1 to conduct automatic testing on the condition of communication between master unit 2 and slave unit 1, an operation of slave unit 1, and the like.

[0033] Automatic fire alarm system 100 according to the present embodiment, in which the use of communication allows master unit 2 and slave unit 1 to exchange various information with each other, can additionally include not only the function of identifying slave unit 1 as the source that issues a notification and the function of conducting the automatic testing as described above, but also various other functions.

Configuration of Master Unit

[0034] In the present embodiment, master unit 2 is a P-type receiver which receives, from slave unit 1, a report of the occurrence of a fire (the fire notification) and a notice for causing another device 3 to operate in coordination (the coordination notification). Master unit 2 is provided in a management room of a building (housing complex 6).

[0035] As illustrated in FIG. 1, master unit 2 includes not only voltage applicator 21, but also resistor 22, receiver 23, transmitter 24, display 25 that displays various data, input unit 26 that receives input from a user, and processor 27 that controls each element.

[0036] Resistor 22 is connected between voltage applicator 21 and at least one of a pair of electrical wires 51 and 52. In the example illustrated in FIG. 1, resistor 22 is inserted between voltage applicator 21 and one (a high potential one) of a pair of electrical wires 51 and 52, that is, electrical wire 51. Note that this example is non-limiting; resistor 22 may be inserted between voltage applicator 21 and the other (low potential) electrical wire 52 or may be inserted between voltage applicator 21 and each of a pair of electrical wires 51 and 52.

[0037] Receiver 23 receives a voltage signal resulting from conversion of an electric current signal from slave unit 1 into a change in voltage signal in a pair of electrical wires 51 and 52 by a voltage drop at resistor 22. Transmitter 24 transmits a transmission signal to slave unit 1.

[0038] When this master unit 2 receives a report of the occurrence of a fire (the fire notification) from slave unit 1, master unit 2 displays, on display 25, the location where the fire occurred and other information.

[0039]  Processor 27 includes a microcomputer as a main element and provides a desired function by executing a program stored in a memory (not illustrated in the drawings). Note that the program may either be written into the memory in advance or be stored in a recording medium such as a memory card and provided in this state.

[0040] Furthermore, master unit 2 includes coordination unit 28 for causing another device 3 to operate in coordination. With this, when master unit 2 receives the coordination notification from slave unit 1, master unit 2 can provide an instruction from coordination unit 28 to another device 3 to cause another device 3 to operate in coordination.

[0041] Master unit 2, which includes voltage applicator 21 that applies a voltage between a pair of electrical wires 51 and 52 as described above, functions as a power supply for operations of entire automatic fire alarm system 100 including slave unit 1 connected to the pair of electrical wires 51 and 52. One example of the voltage which voltage applicator 21 applies between a pair of electrical wires 51 and 52 is direct-current 24 V; it is not intended that the voltage be limited to this value.

[0042] Master unit 2 further includes preliminary power supply 29 that uses a storage battery so that power supply for operations of automatic fire alarm system 100 can be secured even in the event of a power outage. The main power supply of master unit 2 is a commercial power supply, a private electric generator, or the like (not illustrated in the drawings). Voltage applicator 21 automatically switches the power supply source from the main power supply to preliminary power supply 29 in the event of a power outage of the main power supply and automatically switches the power supply source from preliminary power supply 29 to the main power supply after restoration of the main power supply. The specifications, such as electricity capacity, of preliminary power supply 29 are determined to meet a standard stipulated in a ministerial ordinance.

[0043] Resistor 22 has the following two functions: the first function of converting, into a voltage signal, an electric current signal transmitted from slave unit 1 as described above; and the second function of limiting an electric current that flows through a pair of electrical wires 51 and 52 when the pair of electrical wires 51 and 52 is short-circuited. In short, resistor 22 has both the first function as a current-to-voltage converting element and the second function as a current limiting element. One example of the resistance value of resistor 22 is 400 Ω or 600 Ω; it is not intended that the resistance value be limited to this value.

[0044] Receiver 23 and transmitter 24 are electrically connected between resistor 22 and a pair of electrical wires 51 and 52. Note that receiver 23 is not limited to being connected between resistor 22 and a pair of electrical wires 51 and 52 and may, for example, be electrically connected between voltage applicator 21 and resistor 22.

[0045] Receiver 23 receives an electric current signal from slave unit 1 as a voltage signal (a change in voltage) in a pair of electrical wires 51 and 52. Specifically, since the voltage of an electric current which slave unit 1 draws in from a pair of electrical wires 51 and 52 (the drawn current) corresponds to the magnitude of a voltage drop at resistor 22, receiver 23 is capable of receiving, as a voltage signal, the fire notification or the coordination notification from slave unit 1. In other words, receiver 23 receives, as the fire notification or the coordination notification, a voltage signal corresponding to the value of the drawn current in slave unit 1.

[0046] Transmitter 24 transmits, to slave unit 1, a transmission signal that is an electric current signal generated in a pair of electrical wires 51 and 52 by changing an electric current flowing in from the pair of electrical wires 51 and 52. The electric current signal which transmitter 24 transmits (generates) into a pair of electrical wires 51 and 52 is converted into a voltage signal by a voltage drop at resistor 22, and slave unit 1 receives the voltage signal as a transmission signal from master unit 2. In other words, slave unit 1 receives, as the voltage signal, a change in voltage (a voltage signal) that occurs in a pair of electrical wires 51 and 52 when transmitter 24 changes an electric current flowing in from the pair of electrical wires 51 and 52.

Configuration of Slave Unit

[0047] Slave unit 1 includes diode bridge 11, power supply circuit 12, sensor 13, transmitting circuit 14, receiving circuit 15, control circuit 16, and storage 17.

[0048] Diode bridge 11 has input terminals electrically connected with a pair of electrical wires 51 and 52 and output terminals electrically connected with power supply circuit 12, transmitting circuit 14, and receiving circuit 15. Power supply circuit 12 generates power for operations of slave unit 1 from power in a pair of electrical wires 51 and 52. Sensor 13 detects the occurrence of a fire.

[0049]  Control circuit 16 controls transmitting circuit 14 and receiving circuit 15 to cause transmitting circuit 14 to transmit an electric current signal, by adjusting the value of the drawn current according to the output of sensor 13, and to receive, by receiving circuit 15, a transmission signal from master unit 2, for example. Control circuit 16 includes a microcomputer as a main element and provides a desired function by executing a program stored in a memory (not illustrated in the drawings). Note that the program may either be written into the memory in advance or be stored in a recording medium such as a memory card and provided in this state.

[0050] Control circuit 16 includes determiner 161 and controller 162. Specifically, in the present embodiment, determiner 161 which determines an operating state including two states that are the fire notification state and the coordination notification state and controller 162 which controls transmitting circuit 14 to adjust the value of the drawn current are integrally formed. Note that this example is non-limiting; determiner 161 and controller 162 may be formed as separate elements.

[0051] Transmitting circuit 14 is configured to transmit, to master unit 2, an electric current signal that is the value of an electric current drawn in from a pair of electrical wires 51 and 52 (the drawn current). The electric current signal which transmitting circuit 14 transmits (generates) into a pair of electrical wires 51 and 52 is converted into a voltage signal by a voltage drop at resistor 22, and master unit 2 receives the voltage signal as a signal from slave unit 1. In other words, as a result of the adjustment of the value of the drawn current which transmitting circuit 14 draws in from a pair of electrical wires 51 and 52, master unit 2 receives a voltage signal corresponding to the value of the drawn current.

[0052] FIG. 3 illustrates a specific example of transmitting circuit 14. Specifically, as illustrated in FIG. 3, transmitting circuit 14 includes first draw-in unit 141 and second draw-in unit 142 and is configured to draw an electric current in at each of first draw-in unit 141 and second draw-in element 142.

[0053] First draw-in unit 141 has a series circuit including (first) semiconductor element 143, (first) resistor 144, and light emitting diode (LED) 145 which are electrically connected between a pair of output terminals of diode bridge 11. Second draw-in unit 142 has a series circuit including (second) semiconductor element 146 and (second) resistor 147 which are electrically connected between a pair of output terminals of diode bridge 11.

[0054] In this example, each of semiconductor elements 143 and 146 is an NPN transistor, the collector of which is electrically connected to the high-potential output terminal of diode bridge 11. The emitter of semiconductor element 143 is electrically connected to a circuit ground (the low-potential output terminal of diode bridge 11) via resistor 144 and light emitting diode 145. The emitter of semiconductor element 146 is electrically connected to the circuit ground (the low-potential output terminal of diode bridge 11) via resistor 147. The base of each of semiconductor elements 143 and 146 is electrically connected to controller 162. Note that each of semiconductor elements 143 and 146 is not limited to the NPN transistor and may, for example, be a PNP transistor.

[0055] Thus, when controller 162 turns ON semiconductor element 143, transmitting circuit 14 draws an electric current in at first draw-in unit 141, and when controller 162 turns ON semiconductor element 146, transmitting circuit 14 draws an electric current in at second draw-in unit 142. Therefore, transmitting circuit 14 is capable of making a difference in the value of the drawn current between when an electric current is drawn in at first draw-in unit 141 only and when an electric current is drawn in at both first draw-in unit 141 and second draw-in unit 142.

[0056] Furthermore, the value of an electric current drawn in at first draw-in unit 141 can be changed in two steps by changing the base current of semiconductor element 143 in two steps. Likewise, the value of an electric current drawn in at second draw-in unit 142 can be changed in two steps by changing the base current of semiconductor element 146 in two steps. In the present embodiment, as just mentioned, transmitting circuit 14 is capable of adjusting the value of an electric current in two steps at first draw-in unit 141 and in two steps at second draw-in unit 142, that is, in four steps in total. In the following description, it is assumed that slave unit 1 can increase the value of the drawn current gradually in four steps by transmitting circuit 14 changing the value of the drawn current.

[0057] Transmitting circuit 14 can turn ON light emitting diode 145 when an electric current is drawn in at first draw-in unit 141. This light emitting diode 145 is placed in a position where light emitting diode 145 is visible from outside slave unit 1 and has a function of informing a user that slave unit 1 is in the fire notification state.

[0058] Receiving circuit 15 receives a transmission signal from master unit 2 as a voltage signal (a change in voltage) in a pair of electrical wires 51 and 52. Specifically, the electric current signal which master unit 2 transmits (generates) into a pair of electrical wires 51 and 52 is converted into a voltage signal by a voltage drop at resistor 22, and thus receiving circuit 15 receives the voltage signal as the transmission signal from master unit 2. In other words, receiving circuit 15 receives, as the voltage signal, a change in voltage (a voltage signal) that occurs in a pair of electrical wires 51 and 52 when master unit 2 changes an electric current flowing in from the pair of electrical wires 51 and 52.

[0059] Storage 17 stores at least an identifier (address) preassigned to slave unit 1. Specifically, the plurality of slave units 101, 102, 103, ... are assigned with respective unique identifiers. Each of the identifiers is registered in master unit 2 in association with an installation location (such as a room number) of a corresponding one of the plurality of slave units 101, 102, 103, ....

[0060] Furthermore, storage 17 stores a determination condition for determiner 161 to determine the operating state (the fire notification state or the coordination notification state). Examples of the determination condition include a preset threshold value of the output of sensor 13 and the number of times of sampling.

[0061] Determiner 161 regularly reads the output of sensor 13 (a sensor value) and determines the operating state in light of the determination condition stored in storage 17. In the present embodiment, it is assumed that as one example of the determination condition, when the state in which the sensor value exceeds a first threshold value continues a predetermined number of times (for example, three times) of the first sampling, determiner 161 determines that the operating state is the fire notification state. Likewise, it is assumed that when the state in which the sensor value exceeds a second threshold value (greater than the first threshold value) continues a predetermined number of times (for example, three times) of the second sampling, determiner 161 determines that the operating state is the coordination notification state. Note that so as to determine that the operating state is the coordination notification state after it is determined that the operating state is the fire notification state, determiner 161 starts comparing the sensor value and the second threshold value at a point in time when the determination that the operating state is the fire notification state is fixed. These determination conditions are a mere example and can be changed appropriately.

[0062] In the present embodiment, determiner 161 determines which one of the following three states is the current operating state: the fire notification state; the coordination notification state; and a non-fire notification state different from both the fire notification state and the coordination notification state (a normal state). Note the operating state determined by determiner 161 is not limited to the three states and may be only two states that are the coordination notification state and the non-fire notification state and may also be four or more states.

[0063] According to the result of the determination by determiner 161, controller 162 controls transmitting circuit 14 to adjust the value of the drawn current. Specifically, as described above, when the result of the determination by determiner 161 indicates the fire notification state, controller 162 generates the fire notification by adjusting the value of the drawn current to a predetermined fire notification level. When the result of the determination by determiner 161 indicates the coordination notification state, controller 162 generates the coordination notification by adjusting the value of the drawn current to a predetermined coordination notification level. The coordination notification level is a value (an electric current value) different from the fire notification level; in the present embodiment, the coordination notification level is an electric current value greater than the fire notification level (the coordination notification level > the fire notification level).

[0064] Furthermore, in the present embodiment, controller 162 is configured to cause transmitting circuit 14 to transmit a transmission signal representing transmission data, by varying the value of the drawn current between two values, namely, the first level and the second level. The transmission data is, for example, information (an identifier) for identifying slave unit 1 as the source that issues a notification as described above and information for automatic testing. The automatic testing items include, for example, a link check (keepalive) and a self-check of slave unit 1.

[0065] In this example, the first level is a value equal to the fire notification level, and the second level is a value greater than the fire notification level and less than the coordination notification level (the fire notification level = the first level < the second level < the coordination notification level). This means that slave unit 1 varies the value of the drawn current on the basis of the fire notification level and thus can transmit a transmission signal in the fire notification state. In the present embodiment, slave unit 1 is configured to be able to transmit a transmission signal not only in the fire notification state, but also in the non-fire notification state. Specifically, slave unit 1 is capable of transmitting, from transmitting circuit 14, a transmission signal representing transmission data, by varying the value of the drawn current between the second level less than the fire notification level and the first level still less than the second level.

[0066] With this configuration, when a fire occurs and slave unit 1 determines that the operating state is the fire notification state, slave unit 1 generates the fire notification by adjusting the value of the drawn current to the fire notification level. When slave unit 1 determines that the operating state is the coordination notification state, slave unit 1 generates the coordination notification by adjusting the value of the drawn current to the coordination notification state. In the fire notification state, slave unit 1 transmits a transmission signal by varying the value of the drawn current between the first level (the fire notification level) and the second level.

[0067] Note that in the present embodiment, slave unit 1 transmits, to master unit 2, data including at least the identifier stored in storage 17, via communication using a transmission signal. Thus, after master unit 2 receives the fire notification from slave unit 1, master unit 2 can identify, by the identifier included in transmission data represented by the transmission signal, slave unit 1 that is the source that issues the notification.

Operations

[0068] Operations of automatic fire alarm system 100 according to the present embodiment are described below with reference to FIG. 4 and FIG. 5. FIG. 4 is a flowchart illustrating operations of control circuit (determiner 161 and controller 162) 16. FIG. 5 illustrates an electric current flowing through a pair of electrical wires 51 and 52 with the horizontal axis being a time axis and the vertical axis representing voltage values. In FIG. 5, it is assumed that slave unit 1 can increase the value of the electric current flowing through a pair of electrical wires 51 and 52, gradually from base current I0 in four steps, I1, I2, I3, and I4, by changing the value of the drawn current (I0 < I1 < I2 < I3 < I4).

[0069] First, when no notification is issued (in the normal situation), master unit 2 applies, from voltage applicator 21, a constant voltage (for example, direct-current 24 V) between a pair of electrical wires 51 and 52.

[0070] In slave unit 1, determiner 161 reads a sensor value regularly on a predetermined sampling cycle (S1 in FIG. 4) and determines whether or not the operating state is the fire notification state (S2). When the operating state is not the fire notification state (S2: No), slave unit 1 determines that the operating state is the non-fire notification state and repeats reading of a sensor value at determiner 161. In the non-fire notification state, slave unit 1 basically does not draw an electric current in, meaning that the value of the drawn current is 0 (zero). Thus, when every slave unit 1 is in the non-fire notification state, the electric current flowing through paired electrical wires 51 and 52 is only the electric current flowing through terminating resistor 4, meaning that the value of the electric current flowing through paired electrical wires 51 and 52 is basically "I0", as illustrated in FIG. 5. In the example illustrated in FIG. 5, every slave unit 1 is in the non-fire notification state during the period between time t0 and time t3.

[0071] The electric current value I0 is a value of a standby current that flows through paired electrical wires 51 and 52 when every slave unit 1 is in the non-fire notification state (when both the fire notification and the coordination notification are not generated). Master unit 2 uses this standby current to detect disconnection of paired electrical wires 51 and 52. When no standby current flows, master unit 2 determines that there is disconnection of paired electrical wires 51 and 52.

[0072] Note that in the present embodiment, slave unit 1 has a function of transmitting, from transmitting circuit 14, a transmission signal representing transmission data, by varying the value of the drawn current between two values, namely, the first level and the second level, in the non-fire notification state. The first level and the second level in this example are values different from the first level and the second level applied when slave unit 1 transmits a transmission signal in the fire notification state, which are the first level (= the fire notification level) and the second level (> the fire notification level) in the fire notification state. Upon transmitting a transmission signal in the non-fire notification state, the first level and the second level are set to values less than the fire notification level. For example, the first level in the non-fire notification state is 0 (zero), and the second level in the non-fire notification level is a value greater than 0 (zero) and less than the fire notification level (0 = the first level < the second level < the fire notification level).

[0073] Thus, even when every slave unit 1 is in the non-fire notification state, at least one slave unit 1 can transmit a transmission signal by varying the value of the drawn current between the first level in the non-fire notification state and the second level in the non-fire notification state. As a result, the value of the electric current flowing through paired electrical wires 51 and 52 is varied between the two values, as illustrated in FIG. 5. In the example illustrated in FIG. 5, at least one slave unit 1 transmits a transmission signal, and the value of the electric current flowing through paired electrical wires 51 and 52 is varied between "I0" and "I1", during the period between time t1 and time t2.

[0074] Next, in at least one slave unit 1, when the read sensor value meets a predetermined determination condition, and thus the determination that the operating state is the fire notification state is fixed (S2: Yes), controller 162 adjusts the value of the drawn current to the fire notification level by increasing the value of the drawn current (S3). Therefore, when the result of the determination transitions from the non-fire notification state to the fire notification state in at least one slave unit 1, the value of the electric current flowing through paired electrical wires 51 and 52 increases from "I0" to "I2", as illustrated in FIG. 5. In the example illustrated in FIG. 5, at least one slave unit 1 is in the fire notification state during the period between time t3 and time t6.

[0075] Furthermore, in the fire notification state, slave unit 1 has a function of transmitting, from transmitting circuit 14, a transmission signal representing transmission data, by varying the value of the drawn current between the two values, the first level in the fire notification state and the second level in the fire notification state. Therefore, when slave unit 1 transmits a transmission signal in the fire notification state (S4), the electric current flowing through paired electrical wires 51 and 52 is varied between the two values, as illustrated in FIG. 5. In the example illustrated in FIG. 5, at least one slave unit 1 transmits a transmission signal, and the value of the electric current flowing through paired electrical wires 51 and 52 is varied between "I2" and "I3", during the period between time t4 and time t5.

[0076] Thereafter, in slave unit 1, determiner 161 reads a sensor value regularly on a predetermined sampling cycle (S5) and determines whether or not the operating state is the coordination notification state (S6). When the operating state is not the coordination notification state (S6: No), slave unit 1 repeats reading of a sensor value at determiner 161.

[0077] Here, in at least one slave unit 1, when the read sensor value meets a predetermined determination condition, and thus the determination that the operating state is the coordination notification state is fixed (S5: Yes), controller 162 adjusts the value of the drawn current to the coordination notification level by increasing the value of the drawn current (S7). Therefore, when the result of the determination transitions from the fire notification state to the coordination notification state in at least one slave unit 1, the value of the electric current flowing through paired electrical wires 51 and 52 increases from "I3" to "I4", as illustrated in FIG. 5. In the example illustrated in FIG. 5, at least one slave unit 1 is in the coordination notification state during the period after time t6.

[0078] In the present embodiment, for example, it is assumed that the fire notification level is approximately in the range from 20 mA to 25 mA, the coordination notification level is approximately in the range from 40 mA to 45 mA and that the difference between the first level and the second level applied to transmit a transmission signal is approximately in the range from 13 mA to 18 mA. As another example, it may be assumed that the fire notification level is approximately in the range from 5 mA to 8 mA, the coordination notification level is approximately in the range from 15 mA to 20 mA and that the difference between the first level and the second level applied to transmit a transmission signal is approximately in the range from 5 mA to 13 mA.

[0079] The difference between the first level and the second level applied to transmit a transmission signal is not limited to a value that is common between the non-fire notification state and the fire notification state, and the timing for transmitting a transmission signal may be different between the non-fire notification state and the fire notification state. For example, it may be assumed that in the non-fire notification state, the difference between the first level and the second level applied to transmit a transmission signal is approximately in the range from 2 mA to 4 mA.

[0080] Note that these specific numerical values are not intended to limit an embodiment and can be changed appropriately. This means that in the present embodiment, variations in the value of the drawn current are allowed within a predetermined acceptable range. As long as a numerical value is within each acceptable range, master unit 2 can distinguish the current operating state of slave unit 1 between the fire notification state and the coordination notification state.

Advantageous Effects

[0081] With slave unit 1 for automatic fire alarm system 100 according to the present embodiment described above, it is possible to generate the fire notification and the coordination notification by adjusting, according to the result of the determination by determiner 161, the value of the drawn current that is drawn in from a pair of electrical wires 51 and 52. To put it another way, slave unit 1 transmits an electric current signal that indicates the fire notification or the coordination notification in a distinguishable manner by switching the magnitude (the value) of an electric current that is drawn in (flows in) from a pair of electrical wires 51 and 52 between the fire notification level and the coordination notification level.

[0082] This allows master unit 2 for automatic fire alarm system 100 using this slave unit 1 to distinguish the fire notification and the coordination notification from each other without separating lines for the fire notification and for the coordination notification. Thus, slave unit 1 for automatic fire alarm system 100 according to the present embodiment has the advantage of allowing even the P-type system to have the simplest possible configuration and additionally include a function of coordination with another device 3.

[0083] It is preferred that the coordination notification level be an electric current value greater than the fire notification level as in the present embodiment. With this configuration, when the operating state becomes the fire notification state, first, slave unit 1 can increase the value of the drawn current to adjust the value of the drawn current to the fire notification level, and when the operating state becomes the coordination notification state, slave unit 1 can further increase the value of the drawn current to adjust the value of the drawn current to the coordination notification level. This means that slave unit 1 is capable of issuing the fire notification and the coordination notification by increasing the value of the drawn current step by step in accordance with a transition from the non-fire notification state to the fire notification state and further to the coordination notification state.

[0084] It is preferred that the fire notification level be an electric current value greater than an electric current value of a standby current that flows through a pair of electrical wires 51 and 52 while both the fire notification and the coordination notification are not generated as in the present embodiment. With this configuration, master unit 2 is capable of distinguishing the standby current for detecting disconnection of a pair of electrical wires 51 and 52 and an electric current signal which slave unit 1 generates when the fire notification or the coordination notification is generated. Therefore, for example, when any slave unit 1 generates the fire notification in the state in which there is disconnection of a pair of electrical wires 51 and 52, master unit 2 can reliably distinguish the fire notification received from slave unit 1 from the standby current.

[0085] Furthermore, it is preferred that controller 162 be configured to transmit a transmission signal representing transmission data, by varying the value of the drawn current between the first level and the second level as in the present embodiment. With this configuration, slave unit 1 is capable of transmitting, to master unit 2, information (an identifier) for identifying slave unit 1 as the source that issues a notification and information for automatic testing, for example, as described above.

[0086] In this case, it is preferred that the first level be a value equal to the fire notification level and that the second level be a value greater than the fire notification level and less than the coordination notification level. The first level and the second level in this case are the first level in the fire notification state and the second level in the fire notification state, respectively, as described above. With this configuration, slave unit 1 varies the value of the drawn current on the basis of the fire notification level upon transmitting a transmission signal and thus can transmit a transmission signal in the fire notification state. Therefore, immediately after the fire notification is generated, slave unit 1 can transmit, to master unit 2, information (an identifier) for identifying slave unit 1 as the source that issues the notification, for example.

[0087] Automatic fire alarm system 100 according to the present embodiment includes: at least one slave unit 1 described above; and master unit 2 that applies a voltage between a pair of electrical wires 51 and 52. Thus, this automatic fire alarm system 100 has the advantage of allowing even the P-type system to have the simplest possible configuration and additionally include a function of coordination with another device 3.

Embodiment 2

[0088] Slave unit 1 for automatic fire alarm system 100 according to the present embodiment is different from slave unit 1 for automatic fire alarm system 100 according to Embodiment 1 in that the operation period for controller 162 is time-divided into a transmission period and a notification period. In the following description, elements that are similar to those in Embodiment 1 share the same reference numerals, and as such, descriptions thereof are omitted.

[0089] In the present embodiment, controller 162 is configured to transmit the transmission signal in the transmission period and generate the fire notification or the coordination notification in the notification period. In other words, controller 162 does not generate the fire notification or the coordination notification in the transmission period and does not transmit the transmission signal in the notification period.

[0090] Specific descriptions are as follows. In the present embodiment, master unit 2 regularly generates a synchronization signal. When slave unit 1 receives the synchronization signal from master unit 2, slave unit 1 operates for a fixed period in synchronization with the synchronization signal. As illustrated in FIG. 6, the operation period for controller 162 is divided into reception period T1 in which the synchronization signal is received, transmission period T2, and notification period T3.

[0091] Therefore, for example, when any slave unit 1 is in the fire notification state, the period in which this slave unit 1 transmits the transmission signal (transmission period T2) and the period in which this slave unit 1 generates the coordination notification (notification period T3) are clearly distinguished from each other. Thus, master unit 2 can reliably distinguish the transmission signal and notifications such as the fire notification and the coordination notification which are received from slave unit 1.

[0092] Slave unit 1 for automatic fire alarm system 100 according to the present embodiment described above, in which the operation period for controller 162 is divided into the transmission period and the notification period, has the advantage of allowing the transmission signal and notifications such as the fire notification and the coordination notification to avoid interfering with each other. Therefore, it is possible to relatively freely set values for the fire notification level and the coordination notification level without taking interference with the transmission signal into consideration.

[0093] The other elements and functions are similar to those in Embodiment 1.

Embodiment 3

[0094] Slave unit 1 for automatic fire alarm system 100 according to the present embodiment is different from slave unit 1 for automatic fire alarm system 100 according to Embodiment 1 in that, as illustrated in FIG. 7, transmitting circuit 14 includes short circuit 148 that electrically short-circuit a pair of electrical wires 51 and 52. In the following description, elements that are similar to those in Embodiment 1 share the same reference numerals, and as such, descriptions thereof are omitted.

[0095] In the present embodiment, short circuit 148 is provided instead of second draw-in unit 142 provided in the example illustrated in FIG. 3. Short circuit 148 includes, as illustrated in FIG. 3, thyristor 149 electrically connected to a pair of output terminals of diode bridge 11. The gate of thyristor 149 is electrically connected to controller 162.

[0096] Thus, when controller 162 turns ON semiconductor element 143, transmitting circuit 14 draws an electric current in at first draw-in unit 141, and when controller 162 turns ON thyristor 149, transmitting circuit 14 draws an electric current in at short circuit 148. Therefore, transmitting circuit 14 is capable of making a difference in the value of the drawn current between when an electric current is drawn in at first draw-in unit 141 only and when an electric current is drawn in at short circuit 148.

[0097]  In the present embodiment, controller 162 is configured to, when one of the fire notification and the coordination notification is generated, activate short circuit 148 to make the drawn current a short-circuit current. It is assumed that controller 162 activates first draw-in unit 141 when the fire notification is generated, and activates short circuit 148 when the coordination notification is generated. This means that when the coordination notification is generated, controller 162 activates short circuit 148 so that a short-circuit current flows through a pair of electrical wires 51 and 52, and thus adjusts the value of the drawn current to the coordination notification level. Resistor 22 in master unit 2 limits the electric current that flows through a pair of electrical wires 51 and 52 when the pair of electrical wires 51 and 52 is short-circuited by short circuit 148.

[0098] With slave unit 1 for automatic fire alarm system 100 according to the present embodiment described above, when one of the fire notification and the coordination notification is generated, the value of the drawn current can be adjusted using a relatively simple circuit configuration (short circuit 148). Thus, there is the advantage of leading to a cost reduction for slave unit 1. Although the present embodiment describes the example in which controller 162 activates short circuit 148 when the coordination notification is generated, this example is non-limiting; controller 162 may activate short circuit 148 when the fire notification is generated.

[0099] The other elements and functions are similar to those in Embodiment 1. Note that the configuration described in the present embodiment can be applied in combination with the configuration described in Embodiment 2.

[Reference Signs List]

[0100] 

1

slave unit

2

master unit

3

another device

14

transmitting circuit

51, 52

electrical wires

100

automatic fire alarm system

148

short circuit

161

determiner

162

controller

Claims

1. A slave unit for an automatic fire alarm system, comprising:

a transmitting circuit that is electrically connected to a pair of electrical wires to which a voltage is applied and draws an electric current in from the pair of electrical wires as a drawn current;

a determiner that determines an operating state including two states that are a fire notification state in which an occurrence of a fire is reported and a coordination notification state in which another device is caused to operate in coordination; and

a controller that controls the transmitting circuit to adjust a value of the drawn current,

wherein the controller is configured to, when a result of determination by the determiner indicates the fire notification state, generate a fire notification by adjusting the value of the drawn current to a fire notification level that is predetermined, and when the result of determination by the determiner indicates the coordination notification state, generate a coordination notification by adjusting the value of the drawn current to a coordination notification level that is predetermined and different from the fire notification level.

2. The slave unit for an automatic fire alarm system according to claim 1,
wherein the coordination notification level is an electric current value greater than the fire notification level.

3.  The slave unit for an automatic fire alarm system according to claim 2,
wherein the fire notification level is an electric current value greater than an electric current value of a standby current that flows through the pair of electrical wires while both the fire notification and the coordination notification are not generated.

4. The slave unit for an automatic fire alarm system according to any one of claims 1 to 3,
wherein the controller is configured to transmit a transmission signal by varying the value of the drawn current between a first level and a second level, the transmission signal representing transmission data.

5. The slave unit for an automatic fire alarm system according to claim 4,
wherein the first level is a value equal to the fire notification level, and
the second level is a value greater than the fire notification level and less than the coordination notification level.

6. The slave unit for an automatic fire alarm system according to claim 4 or 5,
wherein an operation period for the controller is time-divided into a transmission period and a notification period, and
the controller is configured to transmit the transmission signal in the transmission period and generate either one of the fire notification and the coordination notification in the notification period.

7. The slave unit for an automatic fire alarm system according to any one of claims 1 to 6,
wherein the transmitting circuit includes a short circuit that electrically short-circuits the pair of electrical wires, and
the controller is configured to, when one of the fire notification and the coordination notification is generated, activate the short circuit to make the drawn current a short-circuit current.

8. An automatic fire alarm system, comprising:

the slave unit for an automatic fire alarm system according to any one of claims 1 to 7; and

a master unit that applies a voltage between the pair of electrical wires.

Drawing