JPS593032B2 - induction heating cooker - Google Patents

Description

[Detailed description of the invention] The present invention relates to an induction heating cooker.

In recent years, induction heating cookers for home use have been in the spotlight due to their unique advantages of high safety, cleanliness, high efficiency, and energy saving. In addition to the above-mentioned advantages, induction heating cookers as main cooking utensils are required to have high reliability and operability. Materials that do not allow eddy currents to flow and are highly heat resistant are suitable, but they are more susceptible to mechanical stress than metal casings and can crack or chip, exposing the live parts inside and causing a situation such as an electric shock in the worst case scenario. Therefore, the back of glass or ceramic 15
A method has been adopted to prevent the risk of electric shock by printing a conductive pattern on the surface, and when the impedance increases due to cracks, it prohibits excitation at ultra-audio frequencies, prohibits energization, or shuts off the power supply ( In addition, for household main cookers and commercial use, multi-burner equipment with high output and multiple control devices is extremely convenient in actual use, and also has a completely waterproof structure. There is a need for an output pedestal system for each burner with touch controls that can be used.
The touch control circuit is subject to surge voltage '5 from the outside.
There was a mode in which the internal program would lock up or latch up, resulting in no response to input, resulting in a lack of reliability. As mentioned above, in terms of the product structure, this application allows a part of the casing to be made of very suitable glass, which ensures safety in the event that the glass is broken, and at the same time allows for touch control. This invention relates to an invention that can provide the user with watertight and comfortable operability, and can restore functionality with a simple operation even in the event of an abnormal state caused by an unpredictable external surge.
There are 5. That is, since the output is normally controlled by touch control, protrusions such as switches are not exposed on the surface, which provides great convenience for cleaning and the like.

In addition, even if the touch control circuit stops responding to input due to an external surge, we can provide an induction heating cooker that can easily restore its function with a reset switch installed in the low-voltage top crack protection circuit. This is the object of the present invention. An embodiment of the basic configuration of the present invention will be described below with reference to FIG. In the figure, AC power is applied from l-phase three-wire power supplies 1 and 2 to rectifiers 5 and 6 via triaxes 3 and 4, which are on/off control means, and filter capacitors 7 and 8 are connected in parallel to the rectifier terminals. The filter capacitors 7 and 8 are equipped with chiyoke coils 9 and 1.
0 and a series circuit of frequency converters 11 and 12 are connected, and the superaudible frequency output thereof is supplied to the load (pan) through heating coils 13 and 14. Here, the frequency conversion device may be any commonly known inverter device such as a bridge type semiconductor switching device such as a thyristor or a transistor, but in this embodiment, a thyristor 15 connected in parallel to the power source is used. The explanation will be made using a frequency conversion device consisting of a diode 16 connected in parallel with the heating coil 13 and a resonance capacitor 17 that forms a series resonance circuit and commutates the thyristor 15.This frequency conversion device 1
1 and 12 are touch control circuits 18 and 1, respectively.
It oscillates by supplying the pulse output of 9 to the thyristor, and at the same time the touch control circuit 1
8 and 19 are tri-attack 3 by the user's power-on signal.
, 4 to supply power to the frequency converters 11 and 12. The power supplies of the touch control circuits 18 and 19 are stepped down by power transformers 20 and 21 connected in parallel to the power supplies 1 and 2 so that a power-on signal can be received when the triacs 3 and 4 are turned off. Supplied at ℃・ru. In addition, the power for the top crack protection circuit 22 is supplied by a power transformer 23 whose primary windings are connected to both ends of the power supplies 1 and 2, and the secondary output of the power transformer 23 is connected to the glass or ceramic which forms part of the outer shell. The top crack protection circuit 22 is connected via a series circuit of the conductive pattern 25 printed on the back side and the reset switch 24. It doesn't matter if it is connected to another power supply (.) When the pattern 25 on the back side is cut out or the reset switch 24 is opened, the input power to the top crack protection circuit 22 becomes zero, and the touch control circuit 18 , 19, the contacts of the switches Sγ and S2l inserted in series in the trigger signal circuits of the triacs 3 and 4 are opened to turn off the triacs 3 and 4, and at the same time, the power transformer 20 is turned off. , 21 are connected in series to the primary side of the switch SL,
Open the S2 contact in the same way ℃・Touch control circuit 1
Cut off the power at 8 and 19. The structure of the top crack protection circuit 22 will be explained in more detail with reference to FIG. Figure 2 shows the simplest top crack protection circuit, which consists of a pattern 25 connected in series to the secondary side of a transformer 23 and a reset switch 2.
The input of No. 4 is half-wave rectified by a diode 26, smoothed by a capacitor 27, and converted to DC, and then a voltage is supplied to the coil of a relay 28. Press the reset switch 24 here.
Or, when the back pattern 25 becomes high impedance, the terminal voltage of the capacitor 27 decreases, the relay 28 is no longer excited, all the contacts of Sl, SV, S2, and S are opened, and the triacs 3 and 4 are turned off, and the frequency converter 11 is turned off. ,1
2 stops its operation and the touch control circuit 18,
Since the power transformers 20 and 21 no longer supply power, the circuit 19 is released from program lock and latchup. Here, set the reset switch to the power transformer 20,
It is similar to inserting it into the primary side of 21, but when inserting it into the top crack protection circuit, it has two voltage and current ratings that can reset multiple touch control circuits with one single contact. Because it is small, there is less stress on the switch (3) You can easily check the protection operation in the event of glass or ceramic cracking. Driving the frequency converter may cause insufficient triggering or malfunction, which may destroy the thyristor 15, etc. However, in this application, the top crack protection circuit always operates at the same time, so triacs 3 and 4 are always turned off, resulting in a dangerous situation. A great effect can be expected, such as ℃ never falling into the state.Here, the touch controls 18 and 19 are circuits whose sequences are programmed using a microcomputer or the like.
The configuration according to the present invention will produce great effects for all circuits that use semiconductors such as C-MOSICs that are at risk of latch-up due to external surges. Further, in this application, the triac has been described as a power switch, but the same applies even if it is a mechanical switch such as a relay that can be turned on and off by an external signal.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an induction heating cooker showing an embodiment of the present invention, and FIG. 2 is a circuit diagram of a top crack protection circuit. 11, 12... Frequency conversion device, 13, 14.
．． ... Heating coil, 15... Thyristor.

Claims (1)

[Claims] 1. A plurality of touch control circuits each connected to a different potential, and a top crack protection circuit that detects cracks in the ceramic or glass that forms part of the outer shell of the device using the impedance of the conductive pattern provided on the back side. , a reset switch connected in series to a conductive pattern, a frequency converter that converts from commercial power to an ultra-audible frequency, a heating coil driven by it, and an on/off switch that turns the power on and off using the output of a touch control circuit. and a power transformer for the touch control circuit, the primary winding of which is connected to a commercial power source, and an abnormal output of the top crack protection circuit causes the primary winding or the secondary of the power transformer of the touch control circuit to be turned off. An induction heating cooker configured to prohibit energization of the winding and to prohibit the control signal of the on/off control means.