JPH0456092A - High frequency heating device - Google Patents

Abstract

PURPOSE:To determine a stabilized and optimum thawing time, and realize automation of thawing by performing the integral computing processing with a control means for controlling the high frequency output of a magnetron per each period of an even heating means, and computing a heating time of the material to be heated, and controlling the high frequency output of the magnetron. CONSTITUTION:The output from a microwave detecting sensor 10 is led to an integral circuit 15 through a fan 5 for agitating a microwave with a constant period and an even heating device such as a turn table 12 for turning the material 4 to be heated with a constant period. This circuit 15 performs integral processing per a period of the even heating device to commpute the heating time of the material 4 to be heated with a weight and an initial measured temperature of this material 4 to be heated, and controls the frequency output of a magnetron 1. The optimum thawing time can be thereby obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-frequency heating device that controls heating time depending on the weight, initial temperature, etc. of an object to be heated.

Conventional technology In recent years, high-frequency heating devices have been required to automatically set the heating time based on the weight of the object, initial temperature, etc. when thawing food or other objects, and to be able to finish thawing in optimal conditions. ing.

Conventionally, this type of high-frequency heating device has placed a microwave detection sensor inside the heating chamber as a method of always appropriately heating the object to be heated in accordance with the weight of the object to be heated in the heating chamber. This method uses the characteristic that the reflected microwave power is inversely proportional to the weight of the object to be heated.

That is, the distribution state of microwaves in the heating chamber is influenced by the state of the object to be heated, and if the distribution of microwaves is detected by some means, the state of the object to be heated can be known. Microwave detection sensors apply this principle. This microwave detection sensor detects the microwave energy in the heating chamber with a detection diode, smoothes it, and converts it into a DC signal.The output of this microwave detection sensor drives a timer etc. to finish defrosting. I was doing it.

When the object to be heated in the heating chamber is frozen, the amount of energy reflected from the object to be heated is relatively large due to the characteristics of microwave heating, and this amount of reflected energy is inversely proportional to the weight. As heating progresses and the amount of energy absorbed by the heated object increases, the amount of energy reflected gradually decreases. Therefore, by observing changes in the output signal of the microwave detection sensor, it is possible to know the heating state of the object to be heated. The weight of the object to be heated can be estimated from the correlation with the output of the microwave detection sensor at the beginning of heating, and since the initial temperature of the object to be heated and the change in the heating state are correlated,
By observing the change in the output of the microwave detection sensor over a certain period of time, the initial temperature of the heated object can be determined. Therefore, if the estimated weight and initial temperature are known, the required thawing energy can be calculated by calculation, and the heating time and heating output are determined to defrost the food.

In addition, high-frequency heating devices usually stir the microwaves in the heating chamber or move the object to be heated by rotating it in order to improve uneven microwave distribution or reduce its influence. .

Problems to be Solved by the Invention In such conventional high-frequency heating devices, uniform heating means such as a microwave stirring mechanism or a mechanism for moving the heated object such as a turntable, which is normally used to uniformly heat the heated object, are not used. When used, the output signal of the microwave detection sensor varies greatly with the operation of the uniform heating means. For this reason, the DC signal obtained by detecting and smoothing the output signal of the microwave detection sensor fluctuates greatly, and when processed by a timer,
A wide input voltage range and high-speed calculation were required. For example, when using a microcomputer as a timer, there are problems such as a high-speed microcomputer is required to follow the fluctuating output electrical signals that change from moment to moment, and a large portion of the program processing time is consumed by signal processing. was there.

The present invention has been made to solve the above-mentioned problems, and aims to provide a high-frequency heating device that suppresses and stabilizes fluctuations in the microwave detection signal by uniform heating means in the heating chamber, and can perform processing without requiring high speed. There is.

Means for Solving the Problems In order to achieve the above object, the present invention includes an integrating circuit that integrates an output signal from a microwave detection sensor, and controls the high frequency output of a magnetron by inputting the output of this integrating circuit. The problem solving means is to perform integral calculation processing every time the uniform heating means is synchronized, calculate the heating time of the object to be heated, and control the high frequency output of the magnetron.

The present invention uses the above-mentioned problem-solving means to improve uneven distribution of microwaves or reduce its influence by stirring microwaves in a heating chamber or rotating or otherwise moving an object to be heated. A stable output signal can be obtained by smoothing the output fluctuation of the wave detection sensor using an integrating circuit, inputting it to the control means, and performing integral calculations in accordance with the period of the uniform heating means, which simplifies subsequent signal processing. .

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 6.

As shown in the figure, microwaves excited by a magnetron 1 are guided into a heating chamber 3 by a waveguide 2 and absorbed by an object to be heated 4. After cooling the magnetron l, the air generated by the fan 5 enters the heating chamber 3 through a number of small holes 6 provided on the side of the heating chamber 3, and carries the heat generated as a result of heating the object 4. The air enters the exhaust guide 8 through the numerous small holes 7 in the opposing wall of the heating chamber 3, and is exhausted to the outside of the outer shell 9. A micro detection sensor (hereinafter referred to as a detection sensor) is installed on the ceiling of the heating chamber 3 at right angles to the hole 11.The object to be heated 4 is placed on a turntable 12 for uniform heating, and the turntable 12 is It is rotated by a table motor 13. On the other hand, the intensity of the microwave measured by the detection sensor IO is integrated by an integrating circuit 14 and then input to a control means (hereinafter referred to as a microcomputer) 15.

The detection sensor IO consists of a copper foil pattern 17 etched on a printed circuit board 16 and a chip component 18 as shown in FIG.
The antenna 19 formed by etching is mounted on the plate 2 facing the hole 11 made in the heating chamber 3.
It is installed via 0. As shown in FIG. 4, the signal detected by the antenna 19 is detected by the detection diode 21, and the detected high-frequency voltage is passed through the filter section 22 for only the low frequency component, converted into DC by the smoothing section 23, and then detected. This is the output of the sensor 1o.

The integrating circuit 14 includes a buffer amplifier 24 as shown in FIG.
After making the human impedance sufficiently higher than the output impedance of the detection sensor 1o, the integrating section 25 connects the resistor R.
It is integrated by an integral constant determined by capacitor 0, smoothes output fluctuations due to rotation of turntable I2, and inputs it to microcomputer 15.

As shown in FIG. 6, the signal input to the microcomputer 15 is integrated by an integral counter 26 for one rotation of the turntable I2, and stored in the Va and Vb memory 27, and the weight W of Va is calculated by the W calculation unit 28. The Va-Vb calculation unit 29 calculates Va
-Vb is calculated and stored in Va-Vb memo 1J30, and heating time T is calculated in TI)II: section 31. The heating time T is set in the timer 32, and the subtraction processing section 33 starts subtraction. The content being subtracted is also displayed on the external display unit 34. The switch 35 is turned on during subtraction. When the subtraction process ends, cooking ends.

To explain the operation in the above configuration, turntable 1
If the shape of the heated object 4 placed on the holder 2 is not rotationally symmetrical as shown in FIG. 7, the rotation of the turntable 12 causes the output to suddenly change as shown in the relationship chart between the output of the detection sensor 10 and time shown in FIG. The signal fluctuates greatly. The peak MVp at this time and the rotation period T of the turntable 12
Comparing the average value Vm between 150 and 8-bit microcontrollers, the human power range is V m / V out of 256 levels for an 8-bit microcontroller.
The use of p is limited. The closer Vm/Vp is to 1, the more effectively the signal from the detection sensor 10 can use the 256 input stages of the microcomputer 15. Such a detection sensor 1o
The output of
Vpl is larger than V m / V p and approaches 1,
The 256 stages of the microcomputer 15 can be used effectively, and the calculation precision of the microcomputer 15 can be improved.

The signal after being integrated every rotation period of the turntable 12 in the microcomputer 15 is as shown in FIG.

FIG. 11 shows the relationship between the output of the detection sensor 10 and the weight of the object to be heated 4. Since the output of the detection sensor 10 at the beginning of heating is smaller as the weight of the object to be heated 4 is larger, the weight W is It can be estimated. In addition, Fig. 12 shows the detection sensor 1.
It shows the time change of the output of 0, and by measuring the voltage level Va at the start of heating and the voltage level Vb 1 minute later, and finding the difference between them, it is possible to know the degree of progress of defrosting. Furthermore, the difference in heating time depending on the initial temperature of the object to be heated 4 is known experimentally, and a 10 degree difference in initial temperature results in a difference of approximately 20% in time. Therefore, the optimum decompression time can be calculated from Va-Vb and W.

FIG. 13 is a flowchart of the processing process of the microcomputer 15 that executes the above-mentioned detection process. After the start of cooking, the output of the detection sensor 10 is measured. As shown in FIG. 14, the output of the detection sensor 10 is integrated for 10 seconds corresponding to one turn of the turntable, and this is divided by the integration time of 10 seconds to obtain the integrated output Va. The weight W is calculated from this integral output Va, and 1
After a minute, similar integration is performed to obtain an integral output vb. Calculate the remaining heating time T from W and Va-Vb. After T,
Finish unzipping.

Effects of the Invention As is clear from the above-described embodiments, the present invention includes an integrating circuit that integrates an output signal from a microwave detection sensor, and controls the high-frequency output of the magnetron by inputting the output of the integrating circuit. The means uses integral calculation processing for each period of the uniform heating means to calculate the heating time of the object to be heated and controls the high frequency output of the magnetron, so that it can uniformly heat the microwave stirring mechanism, the object mounting table, etc. As a result of being able to accurately and accurately process the detection sensor output signal regardless of the operation of the means, a stable and optimal defrosting time can be determined, and automation of defrosting can be realized.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram of a high-frequency heating device according to an embodiment of the present invention, Fig. 2 is a partially cutaway front view of the same high-frequency heating device, and Fig. 3 is an exploded perspective view of a detection sensor of the same high-frequency heating device. , FIG. 4 is a circuit diagram of the detection sensor, FIG. 5 is a circuit diagram of an integrating circuit that integrates the output signal of the detection sensor, FIG. 6 is a data flow diagram inside the control means of the high-frequency heating device, and FIG. The figure is a top view of the turntable on which food is placed in the same high-frequency heating device, FIG. 8 is a time change characteristic diagram of the detection sensor output signal, and FIG. 9 is a time change characteristic diagram of the same integration circuit output signal.
FIG. 10 is a time change characteristic diagram of the calculation output signal of the control means,
Fig. 11 is a characteristic diagram of the weight of the object to be heated and the detection sensor output signal, Fig. 12 is a time change characteristic diagram of the detection sensor output signal at different initial temperatures of the object to be heated, and Fig. 13
The figure is a flowchart showing the processing contents of the same door means.
FIG. 4 is a subroutine flowchart of the same flowchart. 1...Mag7tron, 3...Heating chamber,
4...Object to be heated, 10...Microwave detection sensor, 12...Turntable (uniform heating means), 14...Integrator circuit, 15...・・・・・・
・@Go means. Name of agent: Patent attorney Shigetaka Awano and 1 other person 1--Matsunetron MicroviewflWlsen V Figure 2 Figure Figure O Figure Figure Set Figure Figure 2 Figure 10 Figure 13 Figure C 1] Figure 12 Figure 14

Claims (1)

[Claims] a heating chamber in which an object to be heated is placed, a magnetron that supplies high frequency energy to the object to be heated in the heating chamber, a microwave detection sensor that detects the amount of reflection of high frequency energy from the object to be heated in the heating chamber; Uniform heating means such as a mechanism for stirring microwaves at a constant cycle or a table for placing the heated object on which the heated object is placed and moved at a constant cycle; and an integrating circuit for integrating the output signal from the microwave detection sensor. ,
control means for inputting the output of the integration circuit and controlling the high frequency output of the magnetron; the control means performs integral calculation processing for each period of the uniform heating means, calculates the heating time of the object to be heated, and controls the magnetron's output. A high-frequency heating device that controls high-frequency output.