JPH04308683A - High frequency heating device - Google Patents

Abstract

PURPOSE:To improve low-efficiency operation movement which occurs within one-revolution cycle, of the rotary saucer inside a heating chamber. CONSTITUTION:A wave detection circuit 11 detects the change of waves being caused by the rotary saucer 5 inside a heating chamber 3 rotating once, and inputs it into a wave control circuit 12. The wave control circuit 12 continues or interrupts the power source 13 of a magnetron 1 within the one-revolution cycle of the rotary saucer 5 by the comparison between the output of the wave detection circuit 11 and the preset threshold voltage, and improves the low- efficiency operation movement occurring within the one-revolution cycle of the rotary saucer 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating device that controls the timing of radio wave output.

0002

[Prior Art] In recent years, high-frequency heating devices have been used for heating devices such as rotating plates.
There is a strong need to improve the low efficiency operation that occurs within the rotation period.

Conventionally, this type of high-frequency heating device has generally had a configuration as shown in FIG. The configuration will be explained below.

As shown in the figure, a magnetron 1 supplies generated radio waves to a heating chamber 3 via a waveguide 2. In the heating chamber 3, a rotating plate 5 is rotated periodically by a motor 4, and the radio wave state is changed periodically to heat the object 6 to be heated on the rotating plate 5 while improving the uniformity of heating distribution. At this time,
The power source 7 of the magnetron 1 was controlled by a control circuit 8. For example, in order to change the radio wave output, the power supply 7 is controlled intermittently at intervals longer than the unit cycle (16 to 20 msec) of the commercial frequency.

[0005]

[Problems to be Solved by the Invention] In such a conventional high-frequency heating device, the power source 7 is controlled without detecting the state of radio waves in the heating chamber 3, so the device operates in an unfavorable state such as low efficiency operation. There was a problem.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a high-frequency heating device that has a simple configuration and can be operated with high efficiency.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a magnetron that supplies radio waves to a heating chamber;
A power source for the magnetron, a radio wave changing means for periodically changing the radio waves in the heating chamber, a radio wave state detecting means for detecting the state of the radio waves in the heating chamber, and an output of the radio wave state detecting means are inputted to turn on the power source. and a radio wave control circuit for controlling the power source, wherein the radio wave control circuit controls the power source within a change period of the radio wave changing means by comparing the output of the radio wave state detection means with a preset value. is used as a means of solving problems.

[0008]

[Operation] The present invention is capable of controlling the power supply according to the radio wave state generated by the above-mentioned problem solving means, and is one of the radio wave changing means.
It is possible to operate while avoiding inconvenient conditions that occur within the cycle.

[0009]

Embodiment An embodiment of the present invention will be described below with reference to FIG. Note that components having the same configuration as those of the conventional example are given the same reference numerals, and description thereof will be omitted.

As shown in the figure, the rotary plate 5 is rotated by the motor 4 and constitutes a radio wave changing means for periodically changing the radio waves in the heating chamber 3. The antenna 9 is disposed outside an aperture 10 provided in the wall of the heating chamber 3, and its output is input to the radio wave control circuit 12 via a detection circuit 11 (radio wave state detection means). The radio wave control circuit 12 controls the on/off timing of the power source 13 of the magnetron 1 within one rotation period of the rotary plate 5 by comparing the output of the detection circuit 11 with a preset value.

To explain the operation in the above configuration, FIG.
(a) to (c) show examples of time change characteristics of the output of the detection circuit 11, and FIG. It is shown in comparison with VT. T0 is the time (rotation period) required for the rotary plate 5 to rotate once. In Fig. 2(b), in order to reduce the radio wave output, the detection output is set to a threshold voltage VT within the rotation period T0.
This is the detected output waveform when the power supply 13 is stopped for a period of longer T2. FIG. 2(c) is a partially enlarged view of FIG. 2(a).

[0012] Table 1 shows an example of actual measurement when approximately 1000 cc of water was heated as a load.

[0013]

[Table 1]

As is clear from Table 1, efficiency is higher when intermittent control is performed based on the detected output. The reason for the difference in efficiency can be estimated as follows.

FIG. 3 shows a Rieke diagram under the conditions of the above experiment, and the thick circular trajectory in the diagram is the impedance trajectory seen from the magnetron 1 that changes as the rotating plate 5 rotates. The trajectory passes through a combination of radio wave output magnitude/reflectance magnitude. The change in the magnitude of the detection output shown in Fig. 2 is large when the radio wave output is high/high reflectance, and small when the radio wave output is low/low reflectance, so the period when the threshold voltage VT is smaller than The radio waves from the magnetron 1 are efficiently absorbed by the object to be heated 6, and during the period when the voltage is higher than the threshold voltage VT, the radio waves from the magnetron 1 are absorbed by the load in small amounts and are reflected back to the magnetron 1. It is thought that it will come. In this way, by controlling the power supply 13 on and off according to the output of the detection circuit 11, efficiency can be increased.

In the above embodiment, the control of the power source 13 of the magnetron 1 was explained based on experimental values from the viewpoint of efficiency. In addition, there are many other problems such as frequency moting, unnecessary radiation due to sidebands, and even the generation of inconvenient heating patterns within the heating chamber 3. By controlling the output within the rotation time, the degree of inconvenience can be reduced. In addition to the detection circuit 11 of the above embodiment, the means for detecting the radio wave state includes the anode voltage of the magnetron 1,
Current or voltage and current on the low voltage side of a step-up transformer can also be used.

Furthermore, in order to determine the timing for controlling the power supply 13, in addition to the constant comparison with the threshold voltage VT, the
~ 3 cycles) are output continuously, the power supply 13 is stopped during a period T2 that is greater than the set threshold voltage VT, and is operated during the subsequent period (T0 ~ T2), and the power supply 13 is output during a period T2
The output timing may be fixed so that it repeatedly stops at . Further, the power supply 13 may be controlled by an inverter power supply or the like, instead of being switched on and off.

[0018]

As is clear from the above embodiments, according to the present invention, there is provided a magnetron for supplying current to the heating chamber, a power source for the magnetron, and a radio wave changing means for periodically changing the radio waves in the heating chamber. a radio wave state detection means for detecting a radio wave state within the heating chamber; and a radio wave control circuit that inputs the output of the radio wave state detection means and controls the power supply, the radio wave control circuit comprising: a radio wave state detection means for detecting a radio wave state within the heating chamber; Since the power source is controlled within the change period of the radio wave changing means by comparing the output of the radio wave changing means with a preset value, inconvenient conditions such as low efficiency operation that occur within one cycle of the radio wave changing means can be avoided. can be operated.

[Brief explanation of the drawing]

FIG. 1: System configuration diagram of a high-frequency heating device according to an embodiment of the present invention.

[Figure 2] (a) to (c) Time change characteristic diagram of the detected output of the same high-frequency heating device

[Figure 3] Impedance change characteristic diagram of the same high-frequency heating device

[Figure 4] System configuration diagram of a conventional high-frequency heating device

[Explanation of symbols]

1 Magnetron 3 Heating chamber 5 Rotating plate (radio wave changing means) 11 Detection circuit (radio wave state detection means) 12 Radio wave control circuit 13 Power supply

Claims (3)

[Claims] Claim 1: A magnetron that supplies radio waves to a heating chamber;
A power source for the magnetron, a radio wave changing means for periodically changing the radio waves in the heating chamber, a radio wave state detecting means for detecting the state of the radio waves in the heating chamber, and an output of the radio wave state detecting means are inputted to turn on the power source. a radio wave control circuit for controlling the radio wave control circuit, the radio wave control circuit controlling the power source within a change cycle of the radio wave changing means by comparing the output of the radio wave state detection means with a preset value. heating device. 2. The high frequency heating device according to claim 1, wherein the radio wave state detection means is constituted by a detection circuit. 3. The high frequency heating device according to claim 1, wherein the radio wave changing means is configured to rotate a rotary plate by a motor.