JPH022275B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high frequency heating device equipped with a so-called humidity sensor with a cleaning heater.

Configuration of Conventional Example and Its Problems FIG. 1 is an electrical circuit diagram of a high frequency heating device showing a conventional example.

One side of the AC 100V input from the outlet 1 is input to the primary side of the high voltage transformer 2, boosted to a high voltage, and supplied to the voltage circuit 3 to generate a high frequency. The other is supplied to low voltage transformer A4. Secondary coil A5 of low voltage transformer A4
generates a heater voltage for the display tube 6. The coil B7 is a coil having an intermediate tap 8, and after each half-wave rectification and smoothing, a positive voltage with respect to the intermediate tap 8, which is a reference potential, is supplied to the control section 9.
A negative voltage is supplied to the display tube 6. The coil C10 applies a voltage to the heater 12 which heats and cleans dirt adhering to the humidity sensor 11 which detects steam information generated from the object to be heated. The heater 12 is controlled by a signal from the control section 9, and is controlled intermittently by a triax 13, which is a gate trigger element.

Further, the control section 9 receives information from the humidity sensor 11 and performs heating control, and also performs display control on the display tube 6. Relay A14 and relay B15 are also controlled by control section 9.

As described above, conventionally, the power supply of the heater 12 for sensor heating and cleaning is controlled intermittently by the triax 13, which is a gate trigger element.
Dedicated coil C10 is required, and low voltage transformer A
4, the total number of terminals also increases, which has the disadvantage that an inexpensive streamlined transformer with a small total number of terminals cannot be used. In addition, since the point after passing through the triax 13 or heater 12 from the wire C10 is connected to the reference potential of the control unit 9, the voltage seen from the reference potential becomes large, which can cause a big problem in terms of electric shock. I was getting used to it. Furthermore, the wire C10 is a triax 13 which is a semiconductor gate trigger element.
Because it is connected to the reference potential through the semiconductor, if a short circuit with another potential were to occur, there was a risk that the semiconductor would overheat and cause a fire.

OBJECT OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks.
The purpose is to improve the safety of high-frequency heating equipment equipped with a (humidity) sensor that heats and cleans dirt such as oil, improves the safety against electric shock and fires, improves the reliability against noise, and significantly reduces costs. shall be.

Structure of the Invention In order to achieve the above object, the high frequency heating device of the present invention is used as a sensor that detects information such as steam generated from an object to be heated by heating, and cleans dirt attached to the sensor by heating it. Among the heaters in which one end of the heater is shared with a guard ring provided around the sensor terminal, and the heater is turned on and off using a triac, which is a gate trigger element, One end is shared with the reference potential of the control section, and the other terminal is connected to the triax,
Moreover, by making the phase of supplying voltage from the reference potential to the control unit and the phase of supplying voltage to the heater the same phase, the voltage from the reference potential can be suppressed to a low level, and there is an effect that there is no fear of electric shock.

Furthermore, the reference potential on the secondary side of the low-voltage transformer, the power supply reference supplied to the control unit, and the power supply reference supplied to the heater are exactly the same, and the reference potential does not drop to the reference potential through parts such as semiconductors. This also has the effect of completely eliminating the fear of fire, etc. as in the example.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below based on the drawings.

In FIG. 2, an electronic control circuit device 18 is attached to the operation panel 17 of the high-frequency heating device 16. The control unit 9 in the electronic control circuit device 18 inputs information from the operation panel 17 and cooking information from the humidity sensor 11, and controls the magnetron 19.
control intermittently. The propeller fan (fan motor 20) cooling air that cools the magnetron 19 is
The above-mentioned humidity sensor 11 detects the steam entering the heating chamber 21 and exiting from the object to be heated 22, and feeds back the information to the control section 9.

FIG. 3 shows an electrical circuit diagram of the high frequency heating device 16.

One side of the AC 100V input from the outlet 1 is input to the primary side of the high voltage transformer 2, boosted to a high voltage, and then supplied to the high voltage circuit 3, where the magnetron 19 generates a high frequency.

The other one is supplied to the low voltage transformer B23. Secondary coil D24 of low voltage transformer B23
generates a heater voltage for the display tube 6. The coil E25 generates a cathode potential of the display tube 6 using a power supply supplied to the control section 9 and a negative power supply constituted by a diode 26 and an electrolytic capacitor 27.

The coil F28 applies a voltage to the heater 12 which heats and cleans dirt adhering to the humidity sensor 11 which detects steam information generated from the heated object.
One end of the heater 12 has the same reference potential as the control unit 9, and the voltage phase applied to the control unit 9 from this reference potential and the voltage phase applied to the heater 12 are configured to be exactly the same, and the low voltage transformer B23
Since the voltage on the secondary side of the coil E25 and the coil F26 are in the same mode, the voltage between the lines can be suppressed to a low level, and the configuration is extremely safe from the standpoint of electric shock.

Further, the heater 12 is turned on and off by a triax 13 which is a gate trigger element, and a control signal to the triax 13 is outputted from the control section 9.

FIG. 4 is an enlarged detailed view of the humidity sensor 11. A heater 12 is installed around the humidity detection section 29, and heats and cleans adhered dirt. Since the humidity detection section 29 has a high impedance of several + MΩ, a guard ring 31 is placed around the lead-out section 30, and one end of the guard ring 31 is connected to one terminal of the heater 12. In this way, the reference potential on the secondary side of the low voltage transformer B23,
The reference potential supplied to the control unit 9 and the reference potential supplied to the heater 12 are exactly the same, and unlike the conventional example, the reference potential does not drop to the reference potential through parts such as semiconductors, so that heat generation of semiconductors etc. in the event of abnormality, Another effect is that there is no fear of fire caused by ignition.

Furthermore, low voltage transformer 2
Since the voltage phase supplied to each part on the next side is the same, noise countermeasures on the secondary side of the low voltage transformer can be easily implemented.
In the past, when the phase of each part viewed from the secondary side of a low-voltage transformer and the reference potential were different, a great deal of time and cost was wasted to remove noise. This issue has also been greatly improved.

In addition, the number of coils on the secondary side of the low-voltage transformer was reduced by two, from seven in the conventional example to five, which made it possible to use an inexpensive streamlined transformer, resulting in a significant improvement in cost. .

Effect of the invention As described above, according to the present invention, the following effects are obtained.

(1) Since the reference potential of the voltage supplied from the secondary side of the low-voltage transformer to each circuit is common, and the voltage phase of each coil is the same, the low-voltage transformer 2
It is a very safe configuration in terms of electric shock, as the voltage between the lines on the next side can be kept low.

(2) Since the reference potential of the voltage supplied to each circuit from the secondary side of the low-voltage transformer is shared, and there are no semiconductors or other parts passed through it, there is no risk of ignition of semiconductors or fires in the event of an abnormality.

(3) Since the reference potential of the voltage supplied to each circuit from the secondary side of the low-voltage transformer is common, and the voltage phase of each coil is the same, analysis of external noise components is easy, and noise Strong control circuits can be easily created at low cost.

(4) By sharing the voltage phase and reference potential supplied to each circuit from the secondary side of the low-voltage transformer, the number of transformer terminals on the secondary side can be greatly reduced, and an inexpensive streamlined transformer can be used.

[Brief explanation of drawings]

Figure 1 is an electrical circuit diagram of a conventional high-frequency heating device.
Fig. 2 is a block diagram of the main body of a high-frequency heating device showing an embodiment of the present invention, Fig. 3 is an electric circuit diagram of the high-frequency heating device showing an embodiment of the present invention, and Fig. 4 is an external perspective view showing a humidity sensor. It is a diagram. 1...Outlet, 2...High voltage transformer, 3...
...High voltage circuit, 4...Low voltage transformer A, 11...Humidity sensor, 16...High frequency heating device.

Claims (1)

[Claims] 1. A heating chamber that stores an object to be heated, a high frequency oscillator that supplies high frequency waves to the heating chamber, a fan that cools the high frequency oscillator, and a sensor that detects information such as steam generated from the object that is heated. a heater for heating and cleaning dirt adhering to the sensor; a triator for intermittent operation of the heater; and an electronic control circuit device having a control section for controlling them; and a low voltage supply for supplying power to the electronic control circuit device and the heater. one end of the heater is connected to the reference potential of the control unit, the other terminal is connected to the triax, and the phase of the voltage on the secondary side of the low-voltage transformer applied to the heater and the voltage applied to the control unit are connected. A high-frequency heating device configured to have the same voltage phase.