JPH0493520A - Microwave oven - Google Patents

Abstract

PURPOSE:To defrost frozen foodstuffs without being cooked by bringing a heating chamber, in which the foodstuffs are set, to the state of pressure reduction, calculating execution time at each stage on the basis of a function stored in advance in a microcomputer according to the weight of the foodstuffs, and inputting a signal of starting a defrosting operation. CONSTITUTION:After setting a foodstuff 1 in a heating chamber 2 and covering the top of the heating chamber with a lid 7, a signal of the weight of the foodstuff is inputted into a computer through a power feed control device 4 by operating a knob 5. A vacuum pump 6 is operated to start pressure reduction and, when pressure is reduced down to a level of about 100Torr or so, the power feed control device 4 starts to feed power, and execution time T1, T2, T3 at each stage is calculated according to the weight W of the foodstuff to perform heating. This pressure reduction is carried out so that a boiling point becomes sufficiently lower than the coagulation temperature of protein in the foodstuff as time elapses. The adjustment of pressure is done by ON/OFF operation of the vacuum pump while a pressure gage 8 is being confirmed and, when the execution time of T3 elapses, heating is finished. Further, the power feed control device 4 receives a signal from the pressure gage 8 and, when it is determined that discharge is generated if heating is performed with a preset high-frequency output under the condition where pressure in the heating chamber 2 becomes too low, heating is done by reducing the high-frequency output to a level at which it is judged that no discharge is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-frequency heater for defrosting frozen foods by high-frequency heating in a reduced pressure environment.

Conventional technology Conventionally, this type of high-frequency heater was used to thaw frozen foods.
As shown in Japanese Patent Application No. 56-113976, 4
Consisting of two stages, Stage 1 effective high frequency output P + (watts) execution time T
+ (seconds) 2nd stage, effective high frequency output P, (wand) execution time T2
(seconds) 3rd stage, effective high frequency output P, (watts) execution time T,
(seconds) 4th stage, effective high frequency output P, (wand) execution time T,
(seconds).

The effective times T, . . . T4 of each stage are calculated by a predetermined function using the weight of the food inputted from the weight input section as a parameter, and the effective high frequency outputs P, , Pi P3 . P, is P, >P, ≧P, ≧
P, was set to satisfy the following relationship: 1, and was unrelated to the weight of the food.

Problems to be Solved by the Invention Although such conventional configurations have shown a significant improvement in thawing performance, some problems may occur due to factors such as the distribution of radio waves, the size and shape of the frozen food, and the initial temperature of the food. There is a problem that it cannot be safely used for defrosting sashimi, which may cause boiling, and if boiling occurs, it loses its marketability, and most of the thawed food must be frozen.

The present invention solves the above-mentioned problems, and even if frozen foods such as meat and sashimi are sufficiently thawed, they will not become boiled.
The first objective is to provide a high-frequency heater that can defrost faster and better.

A second object is to provide a high-frequency heating device that does not cause a discharge phenomenon even when high-frequency heating is performed in a reduced pressure state.

Means for Solving the Problems In order to achieve the above first object, the present invention has the following features:
The heating chamber in which the food is stored is reduced in pressure, a plurality of predetermined execution stages are set so that the high-frequency output is lowered at each stage, and the execution time of each stage is set according to the weight of the food input from the weight input section. The above-mentioned plurality of predetermined execution steps are executed by calculating using a function stored in the microcomputer in advance and inputting a signal to start defrosting and cooking.

In addition, in order to achieve the second objective, the high frequency output predetermined for each of the plurality of stages is changed at each stage, and the pressure in the heating chamber is changed corresponding to each stage. .

Effect The present invention has the above-described configuration to create a reduced pressure state, and further,
By changing the execution time of each stage according to the weight of the food, the boiling point can be kept below the coagulation temperature of the protein in the food. You can defrost the file without any liability. In addition, by optimizing the heating time for each stage according to the weight, the temperature of the food can be kept below the boiling point, resulting in better thawing with less drip loss.

In addition, by lowering the predetermined high-frequency output for each stage and increasing the pressure in the heating chamber from a high state to a vacuum as thawing progresses, the following An effect like this can be obtained. Generally, as is clear from Paschen's law, atmospheric pressure (7
60 Torr>, the spark voltage is 30 KV/CI, but as it approaches vacuum, the spark voltage gradually decreases, and at 100 Torr, it drops to about 6/v/c+s. Therefore, in the initial stage of heating, when there is no risk of boiling, and when the high frequency output is high, the pressure is set high to prevent discharge. Also, as heating progresses,
Discharge can be prevented by lowering the boiling point by bringing it closer to vacuum and lowering the high frequency output.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 2 is a block diagram of a high frequency heater according to an embodiment of the present invention. A high frequency oscillator 3 is coupled to a heating chamber 2 in which food 1 is housed. High frequency oscillator 3 is controlled by power supply control device 4 . The power supply i control unit 4 includes a microcomputer and the like, and the weight of the food is inputted using a knob 5.

The heating chamber 2 is evacuated and depressurized by the operation of a vacuum pump 6, which is a pressure reducer.

In the time chart in Figure 1, the output is P I
It is configured to change in three stages: t P t and P z. The execution time of each stage is calculated by the power supply control device 4 based on the weight input value W from the knob 5.

The calculation formula is Tn-KnW+C.

The constants Kn and C are constants determined by experiment.

Also, output, PI, Pj, Pj i, tP, >Pj>Pj
It is set so that This is because as thawing progresses, the dielectric constant increases and heating becomes easier.

To explain the actual heating procedure, the food 1 is stored in the heating chamber 2, covered with the lid 7, and the weight is inputted from the power supply control device 4 using the knob 5. The vacuum pump 6 is operated to start reducing the pressure, and when the pressure is reduced to approximately 100 Torr, the power supply control device 4 starts supplying power, and the execution time T of each stage is determined based on the food weight W.
ll T! + T3 is exposed to heat and heated. As time passes, this pressure is reduced so that the boiling point becomes sufficiently lower than the coagulation temperature of the protein in the food, as shown in FIG. The pressure is adjusted by operating the vacuum pump 0N10FFL while watching the pressure gauge 8. When the execution time T3 has elapsed, the heating is finished.

In addition, when the power supply control device 4 receives a signal from the pressure gauge 8 and determines that the pressure in the heating chamber 2 has decreased so much that a discharge will occur if heated with a predetermined high frequency output, the power supply control device 4 will generate a high frequency signal that will determine that no discharge will occur. It is configured to heat up by lowering the output. This insufficient heating caused by lowering the high frequency output is corrected by extending the heating time. Further, whether or not discharge occurs at each of the above-mentioned pressures is determined in advance through experiments and stored in the memory of the microcomputer.

In this embodiment, since heating is started long before the pressure in the heating chamber 2 reaches the final ultimate pressure, the waiting time from the start of operation of the vacuum pump 6 to the start of heating can be shortened. In addition, as thawing progresses, the pressure should be adjusted so that the boiling point is below the coagulation temperature of the protein in the food.
Boiling does not occur, and since the pressure is changed to a low level during heating, the pressure is high in the initial stage when the high frequency output is set to high, making it difficult for electrical discharge to occur, and in the final stage, the pressure is reduced to a low level. When it gets close to the current level, the high frequency output is lowered so that the discharge phenomenon is less likely to occur. In addition, P, P,, P
It goes without saying that more uniform and better decompression can be obtained by providing a time period during which the high frequency output is zero between each stage of .

Effects of the Invention The high-frequency heater of the present invention can lower the boiling point below the coagulation temperature of the protein in the food by creating a reduced pressure state and changing the 7'v line time for each stage according to the weight of the food. Even if conditions such as food shape, initial food temperature, etc. are poor, thawing can be done without causing any overcooking. In addition, by optimizing the heating time for each stage according to the weight, the temperature of the food can be kept below the boiling point, making it possible to achieve better thawing with less drip loss.

In addition, by changing the predetermined high-frequency output for each stage and changing the pressure in the heating chamber according to the progress of thawing, conditions are created that make it difficult for electrical discharge to occur. This makes it possible to provide a high-frequency heater with high reliability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the general configuration of a high-frequency heater according to an embodiment of the present invention, and FIG. 2 is a time chart showing changes in high-frequency output and pressure of the high-frequency heater, which is a life saving device. FIG. 3 is a characteristic diagram showing the relationship between pressure and boiling point. 2... Heating chamber, 3... High frequency oscillator,
4... Power supply control device, 5... Weight input unit, 6... Pressure reducer. Figure 1 / 71D Heat Room 20 Full Picture 61ρ tel Major Prize Input Section Ha B Discontinued

Claims (2)

[Claims] (1) A heating chamber that stores food, a high-frequency oscillator that supplies high-frequency power to the heating chamber, a control device that controls the intensity of the high-frequency output, a pressure reducer that reduces the pressure inside the heating chamber, and the weight of the food. and a control section including a microcomputer for controlling the high frequency output according to a predetermined heating method. A high-frequency heater comprising stages, and the high-frequency output of each stage is changed to a lower value for each stage. (2) Claim in which the predetermined heating method consists of a plurality of stages, in which the high-frequency output of each stage is varied to a low level, and the pressure within the heating chamber is varied to a low level corresponding to each stage. 1. The high-frequency heater according to 1.