JPH03219588A - High frequency heating device - Google Patents

Abstract

PURPOSE:To carry out the thawing of food in a simple structure by cooling a detector means that detects the electric wave received by an antenna in a DC form, by means of the wind of a cooling fan. CONSTITUTION:An opening hole 10 is formed on a heating chamber 2, and a dielectric is provided between the opening hole 10 and an antenna 6. In this structure, the high frequency not absorbed by a food 1 in the heating chamber 2 is leaked from the opening hole 10, is received by the antenna 6, and is detected by a detector 7. When cool wind is going to be blown to the detector 7, by a cooling fan 5 that cools a magnetron 3, the elevator of the temperature of the substrate of the detector 7 as well as of a diode, is heat-insulated with the heating chamber 2, is hindered with each other, and the difference in the detected voltage is eliminated thereby. Stable detection of the weight of the food can be carried out, and simple automation of thawing can thus be achieved.

Description

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

BACKGROUND OF THE INVENTION Conventionally, as an example of automating the thawing state of this type of high-frequency heating device (hereinafter referred to as a microwave oven), there has been an example of automating the thawing state of food as seen in Japanese Patent Application Laid-Open No. 59-207595. This was indirectly understood from the relationship between the temperature dependence of dielectric loss and the detection output in the first wave number band of the oscillation band of the high-frequency radiation means. That is, as shown in Fig. 6, ■ is food, 2 is a heating chamber, 3 is a high frequency radiation means (hereinafter referred to as magnetron), 4 is a transformer for operating the magnetron 3, and 5 is a cooling fan for cooling the magnetron 3. , 6 is an antenna provided inside the heating chamber.

7 is a detection means, 8 is a drive means for varying the high frequency power of the magnetron 3, and 9 is a drive means 8 according to the detection signal.
This is a control means that controls the output of high-frequency power and adjusts the output of high-frequency power.

As a means of determining the amount of load on food 1, when food 1 is in the state of ice crystals at around -18°C, the dielectric loss is small and the high frequency power absorbed by food 1 is small, so it is relatively detected by an antenna. The signal becomes larger. This detected signal has an inversely proportional relationship with the load amount of the food 1 in the heating chamber 2, and the output of the magnetron 3 is controlled by determining the load amount based on the value of the signal.

This kind of control made it possible to thaw food.

Problems to be Solved by the Invention However, in the above configuration, the antenna 6
is placed in the heating chamber and the detection means 7 is brought into contact with the wall surface of the heating chamber 2. If the food is repeatedly heated or heated under no load, the heating chamber becomes hot and the temperature of the substrate rises, causing the detection means 7 to come into contact with the wall surface of the heating chamber 2. There was an issue in which food products of the same weight would show different signal values due to the temperature characteristics of the food.

Further, even if the detection means 7 is separated from the heating chamber 2 to insulate the heat of the heating chamber 2, there is a problem in that it is difficult to manage high-frequency variations in the signal line connecting the antenna 6 and the detection means 7.

Therefore, an object of the present invention is to realize stable thawing of food with a simple configuration.

Means for Solving the Problems In order to solve the above problems, the present invention provides an antenna provided near the opening made in the upper wall or the lower wall of the heating chamber, and an antenna interposed between the antenna and the heating chamber space. It consists of a dielectric and a detection means that is integrated with the antenna and detects the radio waves received by the antenna with direct current, and the detection means is cooled by the wind of a cooling fan.

Function According to the present invention, the detection means has the function of being thermally insulated from the heating chamber and further maintained at a constant temperature by the cold air of the cooling fan.

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

FIG. 1 is a configuration diagram when a detection means is attached to the upper wall of a high-frequency heating device according to an embodiment of the present invention.

Note that the component parts are the same as in the conventional example and are given the same numbers. The antenna 6 is shorter than two wavelengths of the oscillation frequency (2450 MHz) of the magnetron 3, and the antenna 6 is integrated with the detection means 7. Reference numeral 9 denotes a control means (microcomputer in the present invention) which controls the drive means 8 according to the detection signal and adjusts the output of high frequency power.

10 is a hole made in the heating chamber 2 to extract radio waves leaked from inside the heating chamber 2, and 11 is a hole made in the heating chamber 2 and an antenna 6.
It is a dielectric material provided between the

With these configurations, high river waves that are not absorbed by the food 1 in the heating chamber leak through the openings, are received by the antenna 6, and are detected by the detection means 7.

FIG. 2 is a circuit diagram of the detection means 7 for detecting the oscillation signal of the magnetron 3. 12 is a 50 ohm resistor, 13 is a detection diode (for example, Schottky barrier diode), 14.15 is a resistor, and 16 is a capacitor. These detect the high frequency power that is not absorbed by the food 1 in the oscillation frequency band of the magnetron 3, and the voltage ■DC detection is performed as S.

FIG. 3 is a diagram in which the detection means 7 is composed of a microstrip line.

Copper foil patterns 19, 20, 21, 22 are etched onto a dielectric substrate 18 having a certain dielectric constant ER.

The copper foil portion 21 forms 50 ohms of 12, and the portion 22 is grounded. By configuring the detection means 7 on the 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 is improved. .

FIG. 4 is a characteristic diagram showing the signal level of the detection voltage ■S with respect to the weight of the food. This figure shows that there is a large difference in the detected voltage immediately after the start of defrosting, depending on the weight of the food. This is because when the weight of the food is small, less high frequency waves are absorbed and relatively more high frequency waves are detected by the antenna 6.

FIG. 5 shows that when the food 1 (100 grams of frozen minced meat) is thawed in the heating chamber 2, the signal voltage detected by the detection means 7 is affected by the temperature rise of the substrate 15 and the detection diode 13. FIG. The temperature rise is caused by heating under no load (when there is no food in the heating chamber) or by continuous heating. For this reason, even if food of the same weight is thawed, the signal value cannot be used to accurately determine the weight, and the food may become cracked due to excessive thawing and heating. However, if the cooling fan 5 that cools the magnetron 3 is used to blow cold air, the temperature rise of the substrate 15 and the detection diode 13 can be prevented by being thermally insulated from the heating chamber 2, so that the detected voltages will not differ.

In the present invention, the detection means 7 and the apertures 10 are provided on the upper surface of the heating chamber, but they may be provided on the lower surface of the heating chamber, but the present invention is not limited to this embodiment.

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

(1) The high frequency wave in the frequency band of the high frequency radiation means is detected by the antenna-integrated detection means thermally insulated from the heating chamber, and the detection means is cooled by a cooling fan. It prevents temperature rise and enables stable food weight detection, making it easy to automate defrosting.

(2) Since a dielectric material is provided in the opening of the heating chamber, the antenna is prevented from being contaminated by food oil, etc., and signal detection is stabilized.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram 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 plan view of the detection means of the same device configured on a microstrip line, and FIG. A characteristic diagram of the signal. Figure 5 is a characteristic diagram showing the signal when the temperature of the detection means increases and cooling air is blown for 100 grams of minced beef in the same device. Figure 6 is a diagram of the main body configuration of the conventional high-frequency heating device. . 1...Food, 2...Heating chamber, 3. Old...
・High frequency radiation means, 5...Cooling fan, 6...
...Antenna, 7...Detection means, 8...
...Drive means, 9...Control means, 10...
...Open hole, 11...Dielectric material.

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, a driving means which drives the high frequency radiation means, a cooling fan which cools the high frequency radiation means and the driving means, and the driving means. a control means for controlling the heating chamber; an antenna provided near the opening made in the upper wall or the lower wall of the heating chamber; a dielectric body interposed between the antenna and the heating chamber space; The high-frequency heating device includes detection means for direct current detection of radio waves received by the antenna, and the detection means is cooled by the wind of the cooling fan.