JPS5811036Y2 - High frequency heating device - Google Patents

Description

[Detailed description of the invention] This invention detects the temperature by touching or inserting the food in the heating chamber, transmits this signal without going through a transmission line, and uses high frequency heating waves as the transmission power source. The present invention relates to a high-frequency heating device having a container.

A method of controlling high-frequency heating by detecting food temperature has been in practical use for some time, but the advantages of using this method to control without using a transmission line are that a turntable can be used, and when cooking stewed dishes, etc., the lid cannot be closed. The cooking range can be expanded since cooking can be carried out in different ways, and it is convenient to handle and easy to clean.

However, this temperature sensor requires a transmitter, and the transmitter requires a power source.

The transmission power required for the transmitter varies depending on the required S/N and antenna efficiency, and if the external size of such a temperature detector becomes large, the above-mentioned effect will not be utilized, so the antenna must be made sufficiently large. efficiency will decrease.

For these reasons, the power consumption of the transmitter increases, and if a battery is used as a power source, it will consume too much energy and cannot withstand long-term use, so it has been proposed to rectify the high frequency for heating and use it as a power source. ing.

This method eliminates the need for a power switch, improves the airtightness of the temperature sensor, and also improves the airtightness of the temperature sensor.
Although it has the advantage of not emitting interference waves to other equipment, the distribution of high frequency waves inside the heating chamber is complex, and the electromotive force induced in the antenna depends on the output power of the high frequency heating wave, the amount of load, and the position of the antenna. , moving the antenna with a turntable,
A change of several hundred times is shown due to stirring with a stirrer fan, etc.

It is difficult to constantly supply stable power to the transmitter from the induced electromotive force of the antenna, which changes in this way.
High withstand voltage, even in diodes that rectify high frequency waves for heating.
Since a large current is required, in this invention, a diode is selected according to the maximum electromotive force induced in the antenna, and the tank circuit is charged with a constant current using rectified high frequency heating waves until the charging voltage reaches the specified voltage. The high-frequency heating device is controlled by performing so-called intermittent oscillation, in which the transmitter is operated via a constant voltage circuit, and a signal is transmitted only when the transmitter is operable.

This method does not require a large-capacity tank circuit, and the diode that rectifies the high-frequency heating wave does not require high withstand voltage or large current, making the temperature detector compact and inexpensive. It is possible to easily operate the transmitter stably even in an unstable electric field strength distribution.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view of a high-frequency heating device showing one embodiment, in which 1 is a temperature setting dial, 2 is a time setting dial, 3 is a cooking switch, 4 is a menu dial, 5 is a heating chamber, and 6 is a temperature detector. , 7 is a turntable, and 8 is food.

The operation of this high-frequency heating device is that when only the time setting dial 2 is set, cooking is performed by time in the same manner as in the conventional device, and when only the temperature setting dial 1 is set, the food 8 reaches the set temperature. Finish cooking at this point.

In addition, when temperature setting dial 1 and time setting dial 2 are set at the same time, the high frequency output is turned on and off from the time when food 8 reaches the set temperature to keep the temperature of food 8 constant and when the set time has elapsed. Finish cooking at this point.

However, if the high frequency output is completely stopped when off, there will be no power supplied to the temperature detector 6, so the device is configured to emit high frequency output of several tens of W even when off.

FIG. 2 is a block diagram showing the configuration of the high-frequency heating device, in which a microwave receiving antenna 20 receives high-frequency waves for heating, a tank circuit 21 rectifies and smoothes the waves, and stores them as a power source for a transmitter.

A preamplifier 10 converts the signal obtained from the heat-sensitive element 9 into a modulated signal, and a modulation circuit 12 modulates the signal with a carrier wave oscillated by a pre-local oscillator 11, which is then transmitted from a transmitting antenna 13.

This is received by the receiving antenna 14 and sent to the power supply section 17 and the heating high frequency oscillator 19 via the tuning circuit 15 and demodulation circuit 16.
The signal is sent to a control circuit 18 provided between the two.

FIG. 3 is a circuit diagram of the tank circuit 21.

The heating high frequency induced in the microwave receiving antenna 20 is rectified by the high frequency diode 22, and the voltage regulating diode 23
, the capacitor 27 is charged through a constant current circuit formed by the transistor 26 and the resistors 24 and 25.

When the charging voltage of the capacitor 28 exceeds the Zener voltage of the voltage regulator diode 32, PUT (Programmer
bleUni-junction Transisto
r) 30 turns on and triggers the thyristor 33;

When the thyristor 33 is turned on, the PUT 30 is turned off and at the same time, a constant voltage circuit formed by the resistor 36, the constant voltage diode 37, and the I transistors 38 and 39 operates to supply power to the transmitter 40.

When the voltage of the capacitor 27 decreases and the load current accordingly decreases below the holding current of the thyristor 33, the thyristor 33 is turned off, charging of the capacitor 27 is started again, and the above-described operation is repeated.

The discharge starting voltage of the capacitor 27 is determined by the constant voltage diode 3.
2, and the discharge end voltage can be arbitrarily selected by changing the holding current of the thyristor 33 by adjusting the resistor 34.

The capacitor 35 is for increasing the latching current of the 5CR33 to make it easier to turn it on.

According to this method, the capacitor 27 of the tank circuit is charged with a constant current, and when the thyristor 33 is off, the capacitor 27 is charged without wasting power. No electrical current is required and the risk of burnout can be reduced.

For the temperature detector 6 that oscillates intermittently in this way, the control circuit 18 on the receiver side is provided with a delay circuit for several seconds, and even when no reception is being received, the heating high-frequency oscillator 19 can be turned on or off several times. It has the function of maintaining the heating frequency for seconds, and controls the heating high-frequency oscillator from on to off, or from off to on, only when a signal is received.

That is, it also serves as a safety circuit that senses an abnormality and stops the operation of the heating high-frequency oscillator 19 when no signal is received for a predetermined period of time or more.

[Brief explanation of the drawing]

FIG. 1 is an external view of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a block diagram showing its configuration, and FIG. 3 is a circuit diagram of a tank circuit 21. 1... Temperature setting dial, 2... Time setting dial, 6... Temperature detector, 7...
... Turntable, 9 ... Heat-sensitive element, 20.
...Microwave receiving antenna, 40...
transmitter.

Claims (1)

[Scope of utility model registration request] A temperature sensing means that senses the temperature of the food by contacting or inserting it into the food in the heating chamber, a transmitting means that transmits the output signal of the temperature sensing means without going through a transmission line, and a high frequency oscillator for receiving the signal and for heating. a receiving means for controlling the transmitting means, and the power supply for the transmitting means includes an antenna for receiving high frequency heating waves;
It is composed of a diode that rectifies the electromotive force induced in the antenna, a constant current circuit that charges a tank circuit with a constant current, and a constant voltage circuit that supplies a constant voltage to the transmitting means. A high-frequency heating device in which the transmitting means is caused to oscillate intermittently by a switching element that detects and opens and closes.