JPH05157248A - High frequency heater - Google Patents

Abstract

PURPOSE:To so thaw frozen food as not to cause a thawing irregularity or particularly not to melt a surface thereof. CONSTITUTION:A high frequency generator 7 and a chilled air blower 11 are operated by a high frequency wave when a rising speed of a temperature of a surface to be detected by a food surface temperature detector 19 becomes a predetermined value while frozen food 2 is heated by a high frequency warm air generator 13, and a thawing schedule of heating by the generator 7 and cooling by the blower 11 is finished when the surface temperature to be detected by the detector 19 becomes a predetermined value. Accordingly, excellent thawing without irregularities in the surface and the interior of the food can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating apparatus having a function of thawing frozen food.

[0002]

2. Description of the Related Art As prior arts for thawing frozen foods using a high-frequency generating means, the weight of the frozen foods is preliminarily measured, and then high-frequency heating is performed for a time corresponding to the value. As disclosed in Japanese Patent Laid-Open No. 63-38825, there is known one in which the surface temperature of frozen food is detected by an infrared sensor and the high frequency heating source is controlled based on the information.

Further, in order to cope with the fact that the surface of the food is thawed earlier than that inside, as disclosed in Japanese Patent Laid-Open No. 54-36660, cold air is supplied into the heating chamber to freeze the surface of the food during heating. It is also known to maintain.

[0004]

Among these thawing and heating methods, the one in which heating is performed for a time commensurate with the weight of the food product is finished when there is a difference in the initial temperature of the object to be heated. There was a problem that the temperature fluctuated.

On the other hand, an infrared sensor that detects the surface temperature and controls the thawing has an advantage that the absolute value of the surface temperature of the food can be measured, so that the surface temperature can be precisely controlled. The problem is that the temperature is controlled only on the food surface.

[0006] Further, in the case of supplying cold air during heating to prevent the surface from thawing excessively, although an excellent effect is recognized, it has been clarified how to cooperate with the high frequency heating operation. Absent.

That is, in the prior art, there is a problem in the thawing and heating schedule, and it is necessary to set this appropriately.

[0008]

The present invention has been made to solve the above-mentioned problems, and a heating control device is
Heated by the hot air generator, the cold air blower is activated when the food surface temperature rising speed during defrosting and heating detected by the food surface temperature detection device reaches a predetermined value,
After that, when the surface temperature of the food reaches a predetermined value, the thawing schedule for heating by the high frequency generator and cooling by the cold air blower is completed.

[0009]

In the present invention, the frozen food is stored in the heating chamber, and the thawing schedule by heating with warm air is first executed.
From the time when the rising speed of the food surface temperature detected by the food surface temperature detecting device reaches a predetermined value, perform a thawing schedule with cold air by operating the high frequency heating and cold air blowing device, and then the predetermined surface temperature All thawing schedules are terminated when observed, and thawing and heating with no temperature difference from the inside is realized without melting the frozen state of the surface.

[0010]

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

FIG. 1 is a block diagram of a high frequency heating apparatus for carrying out the present invention. In the figure, 1 is a heating chamber formed of a metal plate, 2 is frozen food which is an object to be heated, and 3 is a turntable on which it is rotated. The turntable 3 is connected to a turntable rotation motor 6 via a support base 4 and a rotary shaft 5. Reference numeral 7 is a high frequency oscillator as a high frequency generator. The high-frequency radio wave oscillated from the high-frequency oscillator 7 passes through the waveguide 8 and the excitation port 9 through the heating chamber 1.
It is excited inside and heats the frozen food 2. A cold air blower 11 including a cold air blower, a fan, a motor, etc. is attached near the side wall surface 10 of the heating chamber (1), and the punching unit 1
Cold air is blown to the surface of the frozen food product 2 via the 2. The cool air blowing device 11 is equipped with a cooling element utilizing the Peltier effect so that cold air of about −2 to −5 ° C. is sent into the heating chamber 1.

Reference numeral 13 denotes a hot air heating means, which is a hot air generator for heating food, and an electric heater for generating hot air of about 30 to 40 ° C. and sending it into the heating chamber 1. It is equipped with a fan and operates especially when the ambient temperature is low. And when the ambient temperature is high, room air is taken in as warm air by a fan,
The frozen food 2 is heated without operating the heater.

Next, the surface temperature detecting device for the frozen food 2 will be described.

In FIG. 1, a radiation infrared detector 14, a chopper 15, and a chopper rotating motor 1 are provided above the heating chamber 1.
6 is attached, and a shutter 18 (driving section is not shown, the open state is shown in FIG. 1) for opening and closing the opening 17 is attached on the optical path connecting the radiation infrared detector 14 and the frozen food 2. These constitute the food surface temperature detection device 19. Radiant infrared detector 1
The detection surface 4 is attached downward, and the infrared radiation energy emitted from the frozen food 2 placed on the turntable 3 is transferred to the opening 17 and the shutter 18 formed on the ceiling surface 20 of the heating chamber 1. It is configured to be detected through.

In this structure, the infrared rays radiated from the frozen food 2 are chopped by the chopper 15 and input to the radiation infrared detector 14. The radiation infrared detector 14 determines the temperature of the chopper 15 and the frozen food 2
It outputs the voltage according to the difference from the temperature. That is, a chopper temperature detecting device (not shown) is provided near the chopper 15.
Is provided and the analog signal of the differential voltage output from the radiant infrared detector 14 is corrected based on the output of the chopper temperature detecting device and sent to the surface temperature detecting circuit 22. The temperature detection signal of the surface temperature detection circuit 22 is converted into a digital signal by the A / D converter 23, and a finish determination device (hereinafter abbreviated as microcomputer) 2 including a microcomputer 2
Sent to 1. In FIG. 1, reference numeral 24 is a power source as an electric energy supply device, and 25 is a user's microcomputer 21.
Is a switch for inputting the type of heated food and the heating mode. Reference numeral 26 denotes a timer unit as a heating time measuring device, which is for sending a timer signal to the microcomputer 21. A heating controller 27 controls the turntable rotation motor 6, the high-frequency oscillator 7, the chopper rotation motor 16, the cold air blower 11, and the warm air generator 13 according to a command from the microcomputer 21.

Next, the operation of the present invention will be described with reference to FIG.

FIG. 2 is a characteristic diagram for explaining the present invention. In this figure, a characteristic curve 28 shows a change in the surface temperature of the frozen food, which gradually rises from the surface temperature To at the start of heating and is thawed at the surface temperature Tc. This surface temperature change is realized by the following thawing schedule.

First, the frozen food 2 is placed on the turntable 3 in the heating chamber 1 of FIG. 1, the door is closed, and the surface temperature To at the start of heating is measured by the radiant infrared detector 14.
While measuring the surface temperature while heating the frozen food 2 with warm air (heater heating or room temperature air),
The temperature rise rate is calculated by the microcomputer 21. Then, the surface temperature when the surface temperature rising rate starts to be delayed as compared with the time when heating is started and reaches a preset predetermined surface temperature rising rate is defined as Ta. Ta is about −10 ° C. This surface temperature Ta is the first thawing finish judgment temperature during heating, and after this Ta, the thawing conditions are changed, hot air heating is stopped, and the thawing schedule by high frequency heating, that is, intermittent by turning on and off the high frequency oscillator. While heating and switching to a slow thawing schedule, cooling air is blown into the heating chamber 1 from the cold air blower 11 to prevent partial overheating due to high-frequency heating, especially while preventing abnormal temperature rise on the food surface. The
After that, when the radiant infrared detector 14 detects the predetermined surface temperature Tc, it is determined that the thawing schedule has ended.
In addition, in FIG. 2, Tb is an index surface temperature for switching the cold air blowing schedule, and changes the temperature, the air velocity, the air volume, etc. of the cold air according to the type and quantity of the food.
Further, Tz indicates a surface temperature of 0 ° C., and to to tc indicate heating time.

Next, FIG. 3 shows an example of microcomputer control software in the high frequency heating apparatus of this embodiment, and FIG. 4 shows an example of the relationship between the frozen food surface temperature of the high frequency heating apparatus and the control schedule.

The surface temperature rising rate from the surface temperature To at the start of heating is detected and calculated by the radiant infrared detector 14.
From the time when a predetermined temperature rise rate is reached, thawing is performed according to the high frequency heating and cold air blowing schedule, and it is determined that thawing is completed at the surface temperature Tc, and the high frequency heating device and the cold air blowing device are controlled.

[0021]

As described above, according to the present invention, the frozen food is heated by the hot air generator, and the rising speed of the surface temperature of the frozen food detected by the surface temperature detecting device reaches a predetermined value. When the cold air blower is operated and the surface temperature of the frozen food detected by the food surface temperature detection device reaches a predetermined value, the defrosting schedule by the high frequency generator and the cold air blower is terminated, It has become possible to perform excellent thawing without temperature unevenness with the inside without melting the food surface.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining the present invention.

FIG. 3 is a flowchart showing an example of a decompression method according to the present invention.

FIG. 4 is a time chart showing a frozen food surface temperature and a control schedule in the present invention.

[Explanation of symbols]

 1 Heating Room 2 Frozen Food 7 High Frequency Generator (High Frequency Oscillator) 11 Cold Air Blower 13 Hot Air Generator 19 Food Surface Temperature Detector 21 Finish Judgment Device (Microcomputer) 27 Heating Controller 28 Characteristic Curve

Claims (1)

[Claims] 1. A heating chamber (1) for storing frozen food (2)
A hot air generator (13) for heating the frozen food (2) in the heating chamber (1) with warm air; and a high frequency generator (7) for high frequency heating the frozen food (2). )
A food surface temperature detecting device (19) for detecting the surface temperature of the frozen food (2) during cooking, a cold air blowing device (11) for blowing cold air into the heating chamber (1), and the warm air Operation of the hot air generator (13) when the rising speed of the surface temperature of the frozen food (2) heated by the generator (13) and detected by the food surface temperature detector (19) reaches a predetermined value. The surface temperature of the frozen food (2) detected by the food surface temperature detection device (19) by operating the cold air blower (11) and performing high frequency heating by the high frequency generator (7) High-frequency heating characterized by comprising a control device (21, 27) for terminating the defrosting schedule for heating by the high-frequency generator (7) and cooling by the cold air blower (11) when Location.