JPH046271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device having a solid-state high-frequency generator as a high-frequency heating heat source.

Conventional configurations and their problems Most conventional high-frequency heating devices used magnetrons as high-frequency generation sources, but with the realization of semiconductor devices that operate at high output in high frequency bands, solid-state heating devices constructed using semiconductor devices have been developed. It has become practically possible to use the high-frequency generator as a high-frequency heating heat source. Therefore, longer life and higher performance can be achieved.

By the way, in order to obtain high output at high frequencies using semiconductor elements, a multi-stage amplification configuration is often used. For example, a preamplifier circuit amplifies the output of the oscillation circuit, and a main amplifier circuit further amplifies the output to obtain high output. Semiconductor devices operating at high outputs are characterized in that the input/output impedance of the device changes nonlinearly depending on the high frequency power level input to the device and the device drive voltage level. Moreover, this input/output impedance value is very small. Therefore, when the device starts operating, that is, when a high-frequency power source starts operating or when an amplifier circuit drive voltage is applied, there is a risk that the device will self-oscillate due to impedance mismatch with the device, or electric field concentration will occur, resulting in device destruction. is strong. Furthermore, if the preamplifier circuit is not operating satisfactorily, the impedance of the element becomes large, and a high voltage is applied to the main amplifier circuit, causing destruction of the element.

Purpose of the Invention In view of the above-mentioned points, the present invention aims to prevent the solid-state high-frequency generator mounted on the high-frequency heating device by using element self-oscillation or effective techniques to prevent element destruction. The purpose is to improve reliability.

Structure of the Invention To achieve the above-mentioned object, the present invention provides a main amplifier circuit when it is recognized that the output signal of the output current detection means of the preamplifier circuit drive power supply has deviated from a predetermined reference range after the main amplifier circuit drive power supply starts operating. The apparatus is equipped with a control means for stopping the operation of the amplifier circuit driving power supply.

In this way, element destruction due to fluctuations in the voltage applied to the main amplifier circuit, which occurs when a predetermined current is not flowing through the circuit when the operation of the preamplifier circuit is unstable, is prevented by turning off the power in the event of an abnormality.

Description of examples The present invention will be explained below with reference to the drawings.

FIG. 1 is a partially cutaway external view of a high-frequency heating device showing an embodiment of the present invention.

The main components are a solid-state high frequency generating section 1, a preamplifier circuit current detecting section 2, a driving power supply section 3 for driving the solid-state high frequency generating section 1, and a control section 4 for this driving section. The output from the solid-state high frequency generator 1 is supplied to the heating chamber 6 through the power feeding coaxial line 5.

By inputting the heating time using the time setting key 8 on the operation panel 7 provided on the front of the device and operating the start key 9, a control signal is sent from the control section 4 to the drive power supply section 3 through the lead wire 10. It is sent at a predetermined timing to operate the solid state oscillation circuit power supply, and after a predetermined time delay, the preamplifier circuit power is turned on. Then, with a further delay, the main amplifier circuit power is turned on. When a driving voltage is applied to the main amplifier circuit section, the solid-state frequency generating section 1 outputs a predetermined high frequency power, and the object to be heated in the heating chamber 6 is heated by this high frequency output. Here, when a control signal indicating that a current outside the predetermined range has been detected from the current detection section 2 on the preamplifier circuit power supply line 11 is sent to the control section 4 through the signal line 12, and when heating ends, Alternatively, when the stop key 13 on the operation panel 7 is operated, and when the door 14 used to store the object to be heated in the heating chamber 5 is opened, the information is sent to the control unit 4 and the information is immediately activated. It cuts off the output of the power supply at a predetermined timing.

FIG. 2 is a control system diagram of a high frequency heating heat source showing an embodiment of the present invention. In the figure, the same parts as in FIG. 1 are indicated by the same numbers.

The solid-state high frequency generator 1 includes an oscillation circuit 15 that self-oscillates a high frequency, a preamplifier circuit 16 that amplifies the output of the oscillation circuit, a distributor 17 that equally distributes the output of the preamplifier circuit, and a distributor. It consists of main amplifier circuits 18 and 19 that amplify each of the divided powers, and a combiner 20 that combines the powers of the respective main amplifier circuits.
The drive power supply unit is composed of a drive power supply generator 21 which is a drive applied voltage generation unit, and on/off switches 22, 23, and 24 provided at each output of this generator, and the preamplifier circuit current detection unit 2 is It is provided in the middle of the preamplifier circuit drive applied voltage supply line. A switch 25 turns on and off the supply of the commercial power supply 26 that drives the drive power generator 21, and is operated by a control signal from the control section 4.
27 and 28 are power terminators.

The operation will be explained below. When starting the operation of the solid-state high frequency generator 1, the switch 25 is first closed and the drive power generator 21 starts operating. Next, the switch 22 is closed, the oscillation circuit 15 becomes operational, and then the switch 23 is closed and the preamplifier circuit starts operating. Next, the switch 24 is closed after a predetermined time delay, and the main amplifier circuits 18 and 19 begin to operate, and high frequency power begins to be output. When the current supplied to the preamplifier circuit is outside a predetermined range, a control signal notifying the current is sent from the current detection unit 2, after the heating time is over, when the stop key is operated, and when the When the door is opened, the switch 24 is first opened and the main amplifier circuit is stopped, then the preamplifier circuit 16 and the oscillation circuit 15 are stopped in this order, and finally the starting power source 21 is stopped.

FIG. 3 is a flowchart showing the control sequence. As shown in the figure, when starting the high-frequency heating device,
The oscillator circuit, preamplifier circuit, and main amplifier circuit start operating in this order. Furthermore, when the circuit is stopped, the main amplifier circuit, the preamplifier circuit, and the oscillation circuit are stopped in this order, whether the current is abnormal or the circuit is normally stopped.

By employing the above control method, it is possible to prevent element destruction caused by application of high voltage in a high frequency heating heat source equipped with a solid state high frequency generating section.

Effects of the Invention As described above, the present invention detects the drive current of the pre-amplifier circuit in a high-frequency heating device equipped with a solid-state high-frequency generator, thereby: (1) detecting the driving current of the preamplifier circuit; It has the effect of completely preventing self-oscillation of the harmful element and destruction of the element.

(2) It is possible to provide a highly safe device that operates while confirming the normal state.

It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway external view of a high-frequency heating device showing an embodiment of the present invention, FIG. 2 is a circuit diagram of a system control circuit for the high-frequency heating heat source, and FIG. 3 is a flowchart of the control procedure. 1... Solid state high frequency generation section, 2... Current detection section,
3... Drive power supply unit, 4... Control unit, 15... Solid state oscillation circuit, 16... Preamplifier circuit, 18, 19...
...Main amplifier circuit.

Claims (1)

[Claims] 1. A solid-state oscillation circuit, an oscillation circuit drive power supply that drives the solid-state oscillation circuit that operates in response to a heating operation start operation, a preamplifier circuit that amplifies high-frequency power generated by the solid-state oscillation circuit, and the oscillation circuit. a preamplifier circuit drive power source that drives the preamplifier circuit that operates with a delay from the start of operation of the drive power source;
a main amplifier circuit that further amplifies the output high-frequency power of the preamplifier circuit; an output current detection means for the preamplifier circuit driving power source; and a main amplifier circuit that operates with a delay from the start of the preamplifier circuit driving power source operation. A main amplifier circuit drive power supply for driving an amplifier circuit is provided, and after the main amplifier circuit drive power supply starts operating, it is recognized that the output signal of the output current detection means of the preamplifier circuit drive power supply deviates from a predetermined reference range. The high-frequency heating device includes a control means for stopping the operation of the main amplifier circuit driving power source.