JPH04196087A - High-frequency heating device - Google Patents

Abstract

PURPOSE:To defrost and reheat with simple operation by making decision as to whether to defrost or to reheat based on the deviation from the signal value of a calculating section at the time of start of heating with low-output control of intermittent heating at every cycle of a uniformizing means or continuing the electric power of a high-frequency wave radiating means and carrying out heating control according to the decision during a fixed period of time after start of heating. CONSTITUTION:There are provided a detecting means 11 for detecting a high-frequency power detected with an antenna 10, a convertor 12 for carrying out analog to digital conversion and a calculating section 13 for making digital integration and arithmetic operation of the output signal of the convertor during every cycle of a uniformly heating means 6 at every cycle of commercial power supply. And there are provided a start switch 14 for initiating start of heating, a driving means 5 for making a driving operation according to the signal change of the calculating section 13, a magnetron 3 and a control means 15 for controlling a motor 7. And the control means 15 makes low-output control of making intermittent heating at every cycle of the uniformly heating means 6 or continuing the electric power of a high-frequency wave radiating means 3 during a fixed period of time after start of heating and makes decision as to whether to defrost or to reheat based on the deviation from the signal value of the calculating means 13 and makes heating control, correspondingly and respectively. Thereby, the defrosting and reheating operations may be carried out with simple construction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a high-frequency heating device that achieves automated defrosting and reheating of food products.

2. Description of the Related Art An example of automating defrosting and reheating of this type of high-frequency heating device (hereinafter referred to as a microwave oven) will be described with reference to FIG.

First, in the case of automated food thawing, in order to uniformly heat the food 1 placed in the heating chamber 2, the weight of the food 1 on the turntable 6, which is a uniform heating means, is measured by the weight sensor 2.
The microcomputer 15, which is a control means, controls the drive means 5, and the output of the high-frequency radiation means 3 is controlled via the high-voltage transformer 4. That is, if the weight of a certain food l is detected by the weight sensor 33 after turning on the thawing selection switch 34, the food is adjusted by repeatedly turning the driving means on and off in accordance with the weight as shown in FIG. It was in charge of defrosting control.

In addition, in the case of automating reheating, for example, the weight sensor 3
This was achieved using a gas sensor 35 that separately detects steam from food. That is, reheat selection switch 3
6, if the gas sensor 35 detects an increase in steam from the food 1 along with the heating of the food, as shown in FIG. 6, the heating is stopped.

Problems to be Solved by the Invention However, the above configuration has the following problems.

In the case of food thawing control using a weight sensor, if the starting temperature of the food is a certain predetermined temperature (for example, the freezer temperature -
18'C) or the shape is standard (for example, square), and depending on the thawing start temperature and shape of the food, the food may be boiled or unthawed, resulting in poor thawing results. It was enough. In addition, a weight sensor for measuring the weight of food indicates the same weight no matter where on the turntable the food is placed, but if it is actually placed in the center of the turntable or at the edge. In some cases, even if the thawing time is the same, the food placed on the edge may end up boiling, or even if the weight is the same but the food is flat and rectangular, it may end up boiling in the same way. was there.

In the case of food reheating control using gas sensors, heating is stopped as the amount of steam generated increases as food heats up, but the way steam is generated differs depending on the type of food, There were issues such as overheating and insufficient heating.

To automate defrosting and reheating in a microwave oven, a sensor and a selection start switch must be provided for each, resulting in a complicated configuration and inviting misuse by the user.

Therefore, an object of the present invention is to realize the determination of defrosting and reheating of food without failure using a simple configuration.

Means for Solving the Problems In order to achieve the two objectives, the present invention uses an antenna installed in the heating chamber to measure the progress of heating the food (temperature increases by 1) based on the temperature dependence of the dielectric loss of the food. , is indirectly understood from the relationship with the output of the detection means in the oscillation frequency band of the high-frequency radiation means. and a converter for converting the signal of the detection means from analog to digital; and a calculation section for digitally integrating and calculating the signal after the converter during one period of the uniform heating means for each frequency of the commercial power source, by the control means. , a start switch that starts heating the food, and the control means performs intermittent heating or continuously low output control of the high frequency radiation means at every cycle of the uniform heating means for a certain period of time after the start of heating, and The configuration is such that defrosting or reheating is determined based on the amount of deviation from the signal value at the time of heating start of the calculation unit, and heating control is performed depending on each.

According to the present invention, in order to distinguish between thawed food and reheated food, the signal radio wave from the high-frequency radiating means indicates that if the food is below the freezing point due to an increase in dielectric loss accompanying heating of the frozen food, the high-frequency radio wave is It is difficult to be absorbed by food, and when the water content exceeds the freezing point and increases, high frequencies begin to be absorbed in that part, which has the effect of reducing the detection output.
Since the change in dielectric loss is slow up to 'C', it has the effect of determining the heating start temperature of the food. According to the present invention, in addition to distinguishing between frozen food and reheated food, the absolute amount of signal radio waves from the high-frequency radiation means changes depending on the surface area at the start of heating, so the amount of food in the heating chamber can be determined. It has the function of detecting shapes.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram of the main body of the high-frequency heating device.

1 is a food product, 2 is a heating chamber, 3 is a high-frequency radiation means (hereinafter referred to as a magnetron), 4 is a high-voltage transformer for operating the magnetron 3, and 5 is a drive for driving the high-voltage transformer 4 to vary the high-frequency power of the magnetron 3. Means, 6 is a turntable (one cycle is 10 seconds in the present invention) as a uniform heating means for uniformly heating the food 1, 7 is a motor that drives the turntable 6, and 8 is a part of the heating chamber 1. 9 is an opening cover, 10 is an antenna, 11 is a detection means for detecting the high frequency power detected by the antenna 10, 1
2 is a converter that performs analog-to-digital conversion; 13 is a calculation unit that digitally integrates and calculates the signal after the converter 12 during one period of the turntable 6 for each frequency of the commercial power supply; and 14 is a start switch that starts heating. , 15 is a control means (a microcomputer in the present invention) that controls the drive means 5, magnetron 3, and motor 7 according to signal changes from the calculation section.

FIG. 2 is a circuit diagram of the detection means 11 for detecting the oscillation signal of the magnetron 3. 16 is a 50Ω resistor, 17 is a detection diode (for example, Schottky barrier diode)
, 1, 19 is a resistor, and 20 is a capacitor, which detects the high frequency power that leaks from the opening 8 and is not absorbed by the food 1 in the oscillation frequency band of the magnetron 3, and detects it as a voltage VS.

FIG. 3 is a diagram in which the detection means 11 is composed of a microstrip line.

Copper foil patterns 22, 23, 24, 25, 26 are etched onto a dielectric substrate 21 having a certain dielectric constant ER. The copper foil section 22 has a characteristic impedance of 50Ω, and the section 25.26 is grounded. 27 is the board 21
Through-hole connected to the ground on the back side of 28.29.
Reference numerals 30 and 31 are holes for supporting the detection means 11, and are fixedly supported at the ground 26 by soldering. 32 is a through hole that electrically connects the antenna 10 and the copper foil 22. By integrally configuring the detection means 11 including the antenna 6 using a microstrip line, it is easy to optimally design the length of the line according to the frequency band to be detected, and since this is done by etching, the detection accuracy can be improved. It will improve.

Figure 4 shows the detection means 11 when the food 1 is thawed with different weights in the heating chamber 2 and when the same weight of the food 1 is reheated.
FIG. 3 is a characteristic diagram showing a change in the signal voltage after the signal after the converter 12 is digitally integrated every period (10 seconds) of the turntable 6 and averaged by the calculation unit 13.

As can be seen from Figure 4, the signal value at the start of heating and the amount of deviation from the start of heating for each cycle of the turntable 6 are clearly different between thawed food (below freezing point) and reheated food (above freezing point). You can see that Therefore, the control means 15 operates for a certain period of time after turning on the start switch 14.
The high frequency power of the magnet 103 is turned on and off intermittently at every cycle of the turntable 6, and the pattern of defrosting and reheating of the food is determined based on the amount of deviation during the time of the food temperature judgment unit and the signal value at the start of heating. It can be automatically determined.

In addition, as explained in the operation section, food temperature can be determined because the signal radio waves from the high-frequency radiation means increase the dielectric loss caused by heating the frozen food. If the temperature is below the freezing point, high-frequency radio waves are difficult to be absorbed by food, and when the moisture content increases beyond the freezing point, the high-frequency waves begin to be absorbed by that part, resulting in a decrease in detection output. This is because the change in dielectric loss is slow.

In addition, the reason why the signal value at the start of heating is used to determine the weight and shape of the food is that, as explained in the operation section, the signal radio waves of the high frequency radiation means are This is because the absolute amount changes.

For example, when the weight of the food is small, the amount of radio waves absorbed by the food 1 is small, so the voltage detected by the detection means 11 is high, but in the case of reheated food, the temperature is above the freezing point and the deviation amount changes little. Therefore, it is determined that reheating control is required, and the heating control pattern is executed thereafter.

In addition, the heating control for thawing after determining the food temperature is performed by repeatedly turning high-frequency power on and off, monitoring the amount of deviation to prevent the food from boiling, and taking into account the signal value at the start of heating to ensure that the deviation is small. Stop heating when the temperature reaches the freezing point (the food is close to the freezing point).

In addition, heating control for reheating after determining the food temperature can be done by keeping the high frequency power on, taking into account the signal value at the start of heating, and stopping heating when the temperature has changed by Δ■2. It was found that the optimum finish of food can be achieved by

Incidentally, the change in the amount of deviation may be observed by using a continuous low output control means using an inverter circuit as the drive means 5 for controlling the high frequency power, and the present invention is not limited to one embodiment of the present invention.

Further, the heating control means may control the high frequency power by performing fuzzy inference from the heating start time and the deviation amount, and is not limited to the embodiment of the present invention.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

The temperature and temperature rise of the food can be indirectly detected by the amount of deviation in the signal change of the detection means for each cycle of the turntable, and the shape and weight of the food can be indirectly determined by the signal value at the start of heating. It eliminates uneven heating and overheating of food, and can automatically determine whether to defrost or reheat, so the user only needs to turn on the start switch to achieve defrosting and reheating functions with very simple operations. In addition to this, the configuration is simpler than the conventional case where sensors are used for thawing and reheating.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main body of a high-frequency heating device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the detection means of the same device, FIG. 3 is a diagram in which the detection means is configured with a microstrip line, and FIG.
The figure is a characteristic diagram showing the change in the signal of the detection means with respect to food weight in the case of thawing and reheating, Figure 5 is a main body configuration diagram of a conventional high-frequency heating device, and Figure 6 is the sequence control of thawing and reheating. It is a diagram. 1... Food, 2... Heating chamber, 3...
... High frequency radiation means, 5 ... Drive means, 6.
... Uniform heating means, 10 ... Antenna,
11...Detection means, 12...Analog-to-digital converter, 13...Calculation unit, 14...
...Start switch, 15... Control means. Name of agent: Patent attorney Akira Okaji and two others Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] A heating chamber into which food is taken in and taken out, a high frequency radiation means which supplies high frequency power into the heating chamber from a commercial power source, a driving means which drives the high frequency radiation means, a uniform heating means which uniformly heats the food, an antenna; A detection means for detecting the heating progress state of the food through the antenna, a converter for converting the signal of the detection means from analog to digital, and a control means for controlling the high frequency radiation means, the driving means, and the uniform heating means. a calculation unit that digitally integrates and calculates the signal after the converter during each cycle of the uniform heating means for each frequency of the power source; and a start switch that starts heating the food; is thawed based on the amount of deviation from the signal value at the time of the heating start of the calculation section by intermittent heating at every cycle of the uniform means or continuous low output control of the power of the high frequency radiation means for a certain period of time after the start of heating. , a high-frequency heating device that determines reheating and controls heating accordingly.