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(11) | EP 1 568 294 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Depilatory wax heater |
| (57) A depilatory wax heating device which incorporates at least two different modes of
heating operation, and the capacity to provide a visual indication of (i) the mode
of operation in use and/or (ii) of the required or actual temperature of a heated
receptacle within the device for containing depilatory wax. |
[0001] This invention is concerned with an improved wax heater. More specifically, the present invention relates to a depilatory wax heater, which may be for personal, salon or other professional use.
[0002] Wax heaters of this general type are known, but they suffer a number of disadvantages or limitations. In one known form of depilatory wax heater the temperature control is rather rudimentary and basic, which limits flexibility of use in the device. Little more than basic thermostatically controlled temperature setting is available, and the means for adjusting temperature are somewhat cumbersome and inconvenient. Moreover, in such known depilatory wax heater, a range of different modes of use is not available.
[0003] It is from a consideration of the existing depilatory wax heaters and their attendant disadvantages and limitations, which has led to the development of the present invention.
[0004] Broadly, in accordance with a first aspect, the present invention provides a depilatory wax heating device which incorporates at least two different modes of heating operation, and the capacity to provide a visual indication of (i) the mode of operation in use and/or (ii) of the required or actual temperature of a heated receptacle within the device for containing depilatory wax.
[0005] Preferably the device may include a soft membrane switch panel incorporating one or more switches. Such switches preferably have a gentle push action and may be integrated into the body of the said panel. Such a switch panel may include (a) a mode function display panel, such as an illuminated digital display window of at least two digital character panels, (b) a button to set increase of temperature, (c) a button to set decrease of temperature and (d) a mode function selector switch. In such preferred arrangement, the mode function selector may be adapted to control a function for rapid heat, normal and standby modes of operation as will be explained hereunder. The device will include an electrical and/or electronic circuit by means of which the mode of heating operation can be selected and controlled, and by means of which the temperature may be selected, controlled and displayed.
[0006] The depilatory wax heating device preferably incorporates an illuminated temperature display panel, such as a display window, which is provided with preferably two digital-type alphanumeric display screens, arranged side by side such that one or two alphanumeric characters can be displayed to a user. In order to display temperature selected or required, such screens can be adapted to display numeric characters such as 01 up to 99, although a narrower range of temperature should in practice suffice. In order to display mode, alphabetical characters may be displayed on such screens within such window. For example RH may indicate a rapid heat mode- The circuitry may be so adapted and arranged to flash a numeric display to indicate a required temperature but which has not yet been reached. A non-flashing such numeric display may indicate that the required temperature has been reached.
[0007] It is preferred that the display window be a part of the soft membrane switch panel described above, and that temperature is displayed digitally therein (as well as mode function) by the well known illuminated LED's (light emitting diodes).
[0008] It is convenient for the temperature setting for a receptacle within the device adapted to receive depilatory wax to be adjustable both up and down and preferably within units of one-centigrade degree. It is preferred for separate temperature increase and decrease control buttons to be provided and most preferred for them to be incorporated into the membrane switch panel described above. This provides beneficial flexibility for the user especially when such temperature increase and decrease control buttons are in the near proximity of the mode of heating selector. Such mode of heating selector is therefore also most conveniently arranged as a control switch or button as an integral part of the soft membrane panel described above.
[0009] It is also preferred that the electrical and/or electronic circuitry incorporated into the heating device include at least one microchip arranged to measure, adjust and set the temperature of a heating element within the device, and hence of the depilatory wax receptacle therein. It is also convenient and therefore preferred if the electrical and/or electronic circuitry includes memory means able to retain data corresponding to the last temperature and/or mode settings. In this manner, upon powering the device it may automatically default to the previous such settings but provide full manual override so a user can adjust the mode and temperature at any time beyond such memory stored default settings.
[0010] The present heating device may be programmed to operate in all of normal, rapid heat and standby modes i.e. a minimum of three such modes of operation. These modes are described in further detail below with reference to the illustrated embodiments.
[0011] The heating device preferably incorporates power supply circuitry based on a transformer, rectification diodes, smoothing capacitors and a regulator. Such circuitry preferably also includes an analogue to digital converter and a comparator. The actual heating means may comprise a mica band surrounding the depilatory wax receptacle and connected to a printed circuit board. The temperature of such receptacle may be monitored by a negative temperature coefficient thermistor.
[0012] In order that the invention and further preferred features of it may be illustrated, more easily appreciated and readily carried into effect, embodiments thereof will now be described by way of non-limiting example only with reference to the accompanying drawings and in which:
Figure 1 is an isometric, exploded partial view of a wax heater body assembly, without the internal wax receptacle,
Figure 2 is a side elevation of the remote side of the body assembly depicted in Figure 1,
Figure 3 is a closer detail of a preferred soft membrane switch panel depicted in Figure 2,
Figure 4 is a cross section of one suitable form of depilatory wax receptacle having a removable inner cup which is heated by the device,
Figure 5 is a cross sectional view through the heating device including the depilatory wax receptacle shown in Figure 4,
Figure 6 is a side elevation of the complete device depicted in Figure 5,
Figure 7 is an elevation of the complete device depicted in Figure 4 from the side opposite that shown in Figure 6.
Figure 8 is a circuit diagram showing a suitable heating circuit for the device illustrated in the preceding figures,
Figure 9 is a circuit diagram showing suitable temperature and mode function digital display adapted for use in conjunction with the circuit of Figure 8 and for illuminating display panels DS1 and DS2 according to temperature and/or function selected, and
Figure 10 is an alternative and most preferred circuit diagram described hereunder as circuit description 2.
[0013] Referring to the drawings and initially to Figures 1 and 2, the preferred device 1 shown has an outer shell 8 fabricated of suitable tough plastics material such as ABS, polypropylene or possibly polystyrene although other materials may be suitable. An aperture 2 is provided for the mains power switch (not shown). Conveniently the device has a two part moulded shell with integral handles 3,4, an upper lip 8, an upper removable rim 6 and a closure lid 7. The removable lid is to cover and protect the wax (not shown) to be contained in the receptacle (not shown). The body parts are shown separated for ease of illustration, the finally assembled version is intended to be fixed together, as indicated in figure2. In figure 2, an opening is provided in one shell part to receive a soft membrane switch panel 9 within which a digital display panel 10 is incorporated. The removable rim 6 is intended to catch unintentional spillages of heated wax when removed from the wax receptacle (not shown).
[0014] Referring to figure 3, a preferred soft rubber of other elastomer switch panel 9 is shown in more detail, which is to be fitted to the device as depicted in figure 2. This soft switch panel also functions as the mode and temperature indicator by virtue of the two-digit display window 10 showing alphanumeric characters 14 and 15- A mode select switch 13 is integrally incorporated into the membrane panel to control the heating function- This soft membrane panel 9 also includes a button 11 to increase temperature and a button 12 to decrease temperatures both arranged to operate in increments of one degree centigrade.
[0015] Figure 4 shows one suitable form of depilatory wax receptacle 16 comprising an outer pot subassembly 17 and a removable inner pot 18 which may pass through the rim 6 into and out of the outer pot sub assembly. A mica band heater (not shown) is arranged around the circumference of the chamber within assembly 17 into which the removable wax pot 18 can be fitted and from which it can be removed.
[0016] Referring to figure 5, a cross sectional view of the device including the wax receptacle is shown. Thus receptacle 17 and inner removable pot 18 are visible together with removable rim 6 and lid 7. Figure 6 is a side elevation of the figure 5 arrangement, whereas figure 7 is a view of the remote side with membrane panel 9 visible.
[0017] Figures 8 and 9 are corresponding preferred circuit diagrams of the microprocessor controlled electronic circuitry incorporated within the present device, although not apparent from the earlier described drawings. The function and operation of a preferred embodiment of a depilatory wax heater device will now be described according to the alternative modes of operation: Rapid Heat, Normal Operation, Standby and Temperature Memory function.
Fast Heat :
[0018] Fast Heat is selected by depressing the mode switch until the LED window displays the characters FH. Fast heat has been designed to accelerate the heating process and quickly bring the wax to working temperature. A fast heat cycle will last for approximately 30 minutes.
Normal operation:
[0019] In normal operation the LED window displays temperature in degrees centigrade. The temperature can be set between 25Deg C and 50 Deg C or alternatively between 65 Deg C and 85 Deg C, by pressing either the + button (to increase temperature) or the - button (to decrease temperature). The temperature is displayed in the LED window and changes by 1 Deg C every time the + or - switch is depressed. Holding either button down will automatically adjust the temperature. The LED display continues to flash until the wax reaches the set temperature.
For safety reasons the temperature may not be set above 85 Deg C. In some embodiments, if desired, when an increase in temperature is selected the heater automatically enters the Fast heat cycle to accelerate an increase in wax temperature. These 'micro' Fast heat cycles continue for 1 minute per degree increase, e.g. increasing the temperature from 35 Deg C to 45 deg C is arranged to produce 10 minutes of Fast heat
Standby:
[0020] Standby is selected by depressing the mode switch until the LED window displays two flashing bars (--). Standby is used to simmer the wax during periods of inactivity. Once selected, standby may have to be turned off. This can be done by pressing any of the panel switches.
Temperature memory:
[0021] When the unit is switched off, the temperature it was last set to is retained in the memory. When the heater is switched on it will automatically return to this temperature. This memory is only used to store temperature settings and ignores both standby and Fast heat modes
Over temperature auto shutdown:
[0022] Preferred embodiments of the heater are protected by an over temperature control device. This control device will only operate if the temperature of the receptacle, e. g. aluminium can, becomes too hot. If over temperature occurs the device automatically shuts off the heater until its temperature reaches an acceptable level.
Operation:
[0023] Place the cold pot of wax into the aluminium tank 18. Connect the heater to the mains supply and switch on. Press the + or - buttons until the required wax temperature is displayed on the LED two digit display (Deg C). Next select the Fast heat cycle, by pressing the mode switch until FH is displayed. The display will flash continuously whilst in the Fast heat cycle. Stirring the wax through this cycle will aid the transfer of heat. The Fast heat cycle will last for approximately 30 minutes at which point it will automatically return to the previously set temperature. The wax is now ready to use or decant into a 1000cc work pot. It is recommended that the wax is left in the heater until the temperature stabilises (display stops flashing). The displayed temperature will flash whenever the wax drifts from the set temperature by +/- 5 deg C. Select standby by pressing the mode switch until two flashing centre bars (--) are shown in the LED window. The heater will remain in standby until de-selected or switched off at the mains supply.
Circuit Description 1
[0024] As depicted in Figure 8, the power supply is derived from 12+12 volt centre tapped transformer T1, full wave rectification diodes D1 and D2, smoothing capacitors C1 and C3 and 5 volt regulator U4. T1's centre tap is clamped to earth. The output of U4 is used for the 5 volt supply (Vcc) to components U1, U2, U3 and the LED displays DS1 and DS2. Vcc is clamped to the main supply.
[0025] The heating system is a 300 watt mica band connected to the pcb at J3 and J4. The temperature of the aluminium pot is monitored by a-ve temperature co-efficient thermistor connected to J7 and J8. The resistance of the thermistor and resistor R4 form a potential divider, the centre point of which is connected to the analog to digital converter, which determines the effective temperature of the aluminium pot. U1 fires Q1 which switches the mains supply to the mica band. Resistors R5, R6 and R7 connect to provide the reference voltage for the comparator. The comparator, combined with components R10 and R11 form the zero crossing detector so that the microprocessor only switches Q1 on when the mains current is at zero. It is necessary to use pins 2,3 and 8 of U1 to provide sufficient gate current at Q1. The temperature set-point is modified for each change of temperature setting. Fuse F1 protects the circuit in the event of the mica band going short circuit.
[0026] U1 monitors interrupts from the up (+), down (-) and mode membrane switches at pins 12, 11 and 6 respectively, via SK3. The up and down switch inputs enable the user to adjust in 1°C steps the stabilisation temperature of the aluminium pot. The mode switch is used to select normal, standby or rapid heat modes. Normal is as described above.
[0027] In standby the comparator is forced by software to maintain a temperature of 25°C. In rapid heat mode the comparator is forced by software to maintain a temperature of 120°C, for a period of approximately 25 minutes. After this time the software reverts the set temperature to last setting in normal mode. This is recalled from U3. The temperature set, or mode selected, is displayed on LED's DS1 and DS2. In normal mode the temperature is shown in degrees C. If the temperature is outside the setting (within 5°C) the display flashes. When the set point is reached the display is stable. Standby mode is identified by turning on the two centre bars of the LED displays which continually flash. Fast heat mode is identified by displaying FH. The 2 x 7 segment displays DS1 and DS2 are driven by U2, which is a 16 bit display driver. SK2 is used to supply the display addressing from U2, Vcc and GND to the display pcb via a ribbon cable. SK1 is no longer used.
[0028] The last temperature setting is stored in RAM U3. A switch on U3 is interrogated by U1 and the stored temperature is recalled. For first time operation a default value of 40°is set, and saved.
[0029] Communication between devices U1, U2 and U3 is by Philips I2C protocol, with U1 as the Master.
Circuit Description 2
[0030] As depicted in Figure 10 the power supply is derived from a 12+12 volt centre tapped transformer T1, full wave rectification diodes D1 and D2, smoothing capacitors C1 and C2 and 5volt regulator U3. T 1's centre tap is clamped to earth. The output of U4 is used for the 5 volt supply (Vcc) to components U1 and U2.
[0031] The heating system is a 350 watt mica band connected to the pcb at J1 and J2. The temperature of the aluminium pot is monitored by a -ve temperature co-efficient thermistor connected to J5 and J6. The resistance of the thermistor and resistor form a potential divider with either R3, R7 and R11 or R10 and R8 dependant upon temperature setting. The output from these divider networks feed to U1 pins 2, 3 and 17. U1 fires U3 via opto isolator U4 and switches the mains supply to the mica band. The temperature set-point is modified for each change of temperature setting- Fuse FR1 protects the circuit in the advent of the mica band going short circuit.
[0032] Ulmonitors interrupts from the up (+), down (-) and mode membrane switches at pins 4, 6, and 7, respectively, via CN2. The up and down switch inputs enable the user to adjust in 1°C steps the stabilisation temperature of the aluminium pot. The mode switch is used to select normal, standby or fast heat modes. Normal is as described above.
In standby, the comparator is forced by software to maintain a temperature of 55°C. In fast heat mode the comparator is forced by software to maintain a temperature of 120°C, for a period of approximately 30 minutes. After this time the software reverts the set temperature to last setting in normal mode. This is recalled from U2.
The temperature set, or mode selected, is displayed on LED DS1. In normal mode the temperature is shown in degrees C- If the temperature is outside the setting (within 5°C) the display flashes. When the set point is reached the display is stable. Standby mode is identified by turning on the two centre bars of the LED displays which continually flash. Fast heat mode, is identified by displaying FH. The 15 segment display DS1 are driven by U1 with TR1 and TR2 supplying the required current. CN1 supplies the display addressing from U1 and the 5volt supply to the display pcb via a ribbon cable.
1. A depilatory wax heating device which incorporates at least two different modes of
heating operation, and the capacity to provide a visual indication of (i) the mode
of operation in use and/or (ii) of the required or actual temperature of a heated
receptacle within the device for containing depilatory wax.
2. A device as claimed in claim 1, including a soft membrane switch panel incorporating
One or more switches.
3. A device as claimed in claim2 wherein said switches have a gentle push action and
are integrated into the body of the said panel.
4. A device as claimed in claim 2 or 3, wherein the switch panel includes :
(a) a mode function display panel,
(b) a button to set increase of temperature,
(c) a button to set decrease of temperature, and
(d) a mode function selector switch.
5. A device as claimed in claim 4, wherein (a) comprises an illuminate digital display
window of at least two digital characters.
6. A device as claimed in claim 4 or 5, wherein (d) is adapted to control a function
for rapid heat, normal and standby modes of operation.
7. A device as claimed in any preceding claim including an electrical and/or electronic
circuit by means of which the mode of heating operation can be selected and controlled
and by means of which the temperature may be selected, controlled and displayed.
8. A device as claimed in any preceding claim incorporating an illuminated temperature
display panel having an alphanumeric display.
9. A device as claimed in claim 7 or 8, in which the circuit is adapted to flash a numeric
display to indicate a required temperature but not reached whist flashing.
10. A device as claimed in any one of claims 2 to 9, wherein a display window is part
of the soft membrane switch panel.
11. A device as claimed in claim 10, wherein temperature is capable of digital display
therein with or without mode function.
12. A device as claimed in claim 11, in which the display window is provided with light
emitting diodes.
13. A device as claimed in any preceding claim, in which the temperature setting for a
receptacle linked to a receptacle in the device for receiving wax is adjustable up
and down in units of 1 Deg Centigrade.
14. A device as claimed in any preceding claim wherein separate temperature increase and
decrease buttons are present.
15. A Device as claimed in claim 14, wherein the said separate buttons are incorporated
within a membrane switch panel as defined in claim 2.
16. A device as claimed in any preceding claim wherein a mode of heating selector is also
present as a control switch or button as an integral part of a membrane switch as
defined in claim 2.
17. A device as claimed in any one of claims 7 to 16 wherein the circuit includes at least
one microchip arranged to measure, adjust and set the temperature of a heating element
within the device and optionally of the wax receptacle.
18. A device as claimed in any one of claims 7 to 17, wherein the circuit includes memory
means able to retain data corresponding to a previous temperature and/or mode setting.
19. A device as claimed in claim 18 adapted to default to a previous setting but with
manual over- ride facility for user adjustment of mode and/or temperature.
20. A device as claimed in any preceding claim incorporating at least three different
modes of heating operation or cycle.
21. A device as claimed in claim 20, in which the said modes are normal, fast heat and
standby.
22. A device as claimed in any preceding claim, including power supply circuitry based
on a transformer, diodes, smoothing capacitors and a regulator.
23. A device as claimed in claim 22, in which the circuitry also includes an analogue
to digital converter and a comparator.
24. A device as claimed in any preceding claim in which the heating means comprises a
mica band surrounding the wax receptacle and connected to a printed circuit board.
25. A device as claimed in any preceding claim in which the temperature of the wax receptacle
is monitored by a negative temperature coefficient thermistor.