JPH0340290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to thawing of frozen foods by high frequency heating.

Conventional structure and problems In general, thawing involves external heating thawing using heat conduction and internal heating thawing using high frequency heating. Thawing is caused by heat sensitivity, which increases the enthalpy of the food.

In this method, the frozen food thaws from the periphery to the center. External heating thawing involves thawing using an electric heater, hot water, infrared light bulb, etc. External heating thawing takes a long time because food products generally have poor thermal conductivity. When the outer layer melts and becomes water, that part has a lower thermal conductivity than ice, so the conduction to the inside becomes poor, so when thawing it is placed in the same temperature range from the initial temperature to the final temperature during freezing. It takes almost twice as long as the time required for freezing. The fact that thawing takes a long time results in quality differences even in the solid state immediately after thawing.

In contrast, defrosting using high-frequency radio waves generates heat in the food itself to increase enthalpy and defrost the food. Thawing progresses very quickly because the frozen food itself is thawed from the surface and from the inside using radio waves as a heating element, and for this reason, the quality of the solid is generally uniform and stable.

Although internal heating thawing is superior to external heating thawing, conventional high-frequency heating equipment requires careful consideration of the ambient temperature, radio wave distribution, the size, shape, and weight of frozen foods, and the difference in dielectric constant between water and ice. Because this was not done, problems often occurred when thawing with a high-frequency heating device.

In order to eliminate the drawbacks of thawing using high-frequency heating, high-frequency heating devices that control the heating pattern according to the weight of frozen foods using microcomputers (hereinafter referred to as microcomputers) have recently become available on the market. It has been evaluated.

That is, each stage has a plurality of execution stages consisting of a predetermined constant high frequency output, and the execution time of each stage is stored in advance in the microcomputer according to the weight of the food input from the weight input section. By inputting a signal to start defrosting and cooking, the system executes the multiple predetermined execution steps described above and achieves faster and better defrosting of frozen foods. It was hot. According to this method, it is possible to raise the external temperature and internal temperature of food in the most ideal way, but this is only possible when the external temperature and the temperature inside the heating chamber are at a certain temperature. It was hot. In other words, there can be a 40 degree difference in external temperature between summer and winter, and among high-frequency heating devices, there is a so-called microwave oven with a built-in electric heater, which is the most widely available on the market. Thawing frozen foods resulted in a completely different food temperature rise. This had some drawbacks, such as depending on the environment, heating may end without being defrosted, or conversely, most of the food may end up being boiled.

Purpose of the Invention The present invention solves the above-mentioned conventional drawbacks, and has few failures under any conditions, and
The purpose is to defrost frozen foods better.

Structure of the Invention In order to achieve the above object, the high-frequency heating device of the present invention is provided with a temperature sensor that detects the internal temperature of the heating chamber, and uses the information obtained by the temperature sensor through a control unit including a microcomputer. In addition to displaying information on the display section for providing information to the user, the device also has an input section for adjusting the finished product so that the user can select a heating pattern based on the temperature information, and the temperature in the heating room is such that the temperature in the heating room is such that the frozen food can be thawed and heated properly. By adopting a control configuration that does not perform heating operation even if the start signal is input when the temperature is in a low temperature range, frozen foods can be thawed quickly and with almost no failures in any environment. It is effective.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 3, the input unit 1 has a thawing key 2 for selecting thawing, and the thawing key 2 can simultaneously set the weight of the frozen food by tapping. When an input signal is input to this decompression key 2,
A signal is sent via the input control section 3 to a central control section 4 including a microcomputer. The central control unit 4 stores a plurality of heating patterns for controlling the magnetron 15, and also controls the display tube 5 based on input signals.
The set weight will be displayed. Further, the temperature sensor 6 is provided at a position where it can detect the atmosphere inside the heating chamber 7, and the temperature detected by the temperature sensor 6 is A/D converted by the central control unit 4, and is converted into multiple levels by a comparator. The central control unit 4 displays on the display tube 5 an approximate temperature value corresponding to that range. The heating pattern stored in the central control unit 4 is also determined corresponding to the classification. The user presses the temperature key 8 provided on the input section 1 according to the displayed temperature.
By tapping , the temperature correction lamp 9 below the displayed temperature value will match.

Next, when a start signal is input to the input section 1, the relay drive control section 10 turns on the first relay 11 via the input control section 3 and the central control section 4. When the first relay 11 is turned on, a high frequency oscillation circuit including a high voltage transformer 12, a high voltage capacitor 13, a diode 14, and a magnetron 15 oscillates a high frequency. Further, the first relay 11 is turned on and off (OFF) according to a pattern stored in advance in the microcomputer of the central control unit 4, depending on the type of the object to be heated that is selectively input to the input unit 1. do. Reference numeral 19 is a low voltage transformer that supplies power to each control section. Reference numeral 17 denotes a heater for electrically heating the object to be heated, and is turned on and off by the second relay 16.

The operation of the above structure will be explained below with reference to FIGS. 4 to 6.

First, we will explain the relationship between the high frequency output operation pattern and the temperature rise of the frozen food 18 when the internal temperature of the heating chamber 7 is in a normal state, that is, around 10°C to 20°C, and the frozen food 18 is thawed. Fifth
Shown in Figures a and b. In the same figure, the continuous high output first takes a certain period of time T ₁ , and then the rest period T ₂
The output changes to intermittent output by placing . After this time T ₃ has elapsed, a pause time T ₄ is further passed, and the operation ends with the final intermittent small output operation. Let this intermittent small output time be _T5 . These respective output levels and times are determined by multiplying the input weight of the frozen food by a pre-stored function. The temperature always remains below 5°C, allowing ideal thawing.

Next, a description will be given of defrosting when the temperature inside the heating chamber 7 is relatively high, that is, after continuous operation or in midsummer. FIG. 5c is a graph showing the temperature rise of the frozen food 18 when the heating operation is performed in the same manner as the heating pattern described above even though the inside of the heating chamber 7 is at a high temperature. The temperature of surface area A has a steep rise curve due to both the high frequency and the external atmosphere heating, and from around 0℃, where ice becomes water, the dielectric constant suddenly increases, so the rise becomes even more rapid. It cooks in a short time. Figures 6a and 6b are diagrams showing the relationship between the heating pattern and the temperature rise of frozen food when temperature correction is performed using the temperature key 8 when the internal temperature of the heating chamber 7 is high as described above. As is clear from the above, by shortening the continuous high-power operation time T ₁ and lengthening the pause time T ₂ , the temperature of the frozen food 18 can be thawed in an ideal manner without a sudden rise. .

Next, when thawing at an extremely high temperature after heating with the electric heater 17 for cooking in an oven, etc., even a small amount of high-frequency output irradiation will cause the surface area A to
Since it can be boiled in a short time, by displaying the temperature on the display section 1, the user can use it as a guide for the cooling waiting time. Also, if the user becomes sick and sends a start signal, the temperature remains at a certain level (approx.
The microcomputer is programmed not to perform high-frequency oscillation at temperatures above 100°C.

In this way, according to this embodiment, a heating pattern is selected according to each environment, and a very precise thawing state can be obtained quickly. In addition, at high temperatures, the user can know the approximate waiting time, and even if the machine starts by mistake, it will not fail and food will not be wasted. In addition, when heating with an electric heater, a temperature sensor is generally used to control the temperature.
The high-frequency heating device with an electric heating device does not increase the cost at all.

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

(1) Frozen foods can be thawed quickly and in extremely good condition depending on their weight, and when the temperature is extremely high, users can receive information such as estimated waiting times and danger signals, which improves performance. It is possible to provide a high-frequency heating device that is extremely easy to use.

(2) There will be no thawing failures when the temperature inside the heating chamber is extremely high, and there will be no wastage of frozen foods.

(3) Even under any temperature environment, the shortest heating operation time and the best thawing condition can be obtained according to the temperature condition.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view of a high-frequency heating device that is an embodiment of the present invention, and FIG. 2 is a control circuit diagram of the device.
Fig. 3 is a perspective view of the main parts of the device, Fig. 4 is a cross-sectional view of frozen food, and Fig. 5 a, b, c and Fig. 6 a, b are operational characteristics diagrams of the device during thawing and heating. be. DESCRIPTION OF SYMBOLS 1...Input part, 2...Decompression key, 3...Input control part, 4...Central control part, 5...Display tube (display part), 6...Temperature sensor, 7...Heating chamber, 9... …
Temperature correction lamp, 15... Magnetron (high frequency generation means), 17... Electric heater, 18... Frozen food (object to be heated).

Claims (1)

[Claims] 1. A heating chamber for storing and heating an object to be heated, a high-frequency generating means for high-frequency heating the object to be heated, a control section for controlling the high-frequency generating means with a plurality of predetermined heating patterns, It has a temperature sensor that detects the temperature inside the heating chamber,
The control section has a comparison means for classifying the temperature detected by the temperature sensor into a plurality of stages, and selects a heating pattern corresponding to the classification determined by the comparison means, and controls the high frequency generation means. High frequency heating device having means.