JPH0539929A - High frequency heater - Google Patents

Abstract

PURPOSE:To defreeze freezed food without occurrence of uneven defreezing, in particular, facial melting. CONSTITUTION:If the rate of rising of facial temperature detected by a facial temperature detecting means 18 reaches a prescribed value while freezed food 2 is heated by a high frequency wave heat energy generating means 7, a cold wind fan 11 is started. After that, if the facial temperature detected by the facial temperature detecting means 18 reaches the prescribed value, a defreezing schedule of heating by the heat energy generating means 7 and cooling by the cold wind fan 11 is finished. By this, an excellent defreezing can be obtained in which no temperature unevenness is generated both on the surface and inside the food.

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 heating source, 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, as seen in Japanese Patent Laid-Open No. 54-36660, in order to cope with the fact that the surface of the food product is thawed faster than the inside thereof, cold air is supplied into the heating chamber so that the surface of the food product during heating is cooled. Some are known to maintain a frozen state.

[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]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the heating control means has a predetermined surface temperature rising speed during defrosting and heating detected by the surface temperature detecting means. When the value reaches a value, the cold air blower is operated, and when the surface temperature of the food reaches a predetermined value thereafter, the thawing schedule for heating by the high-frequency heat energy generating means and cooling by the cold air blower is ended.

[0009]

In the present invention, the frozen food is stored in the heating chamber, the thawing schedule by the high frequency heating is first executed, and the temperature rising speed of the food surface detected by the surface temperature detecting means reaches a predetermined value. Then, the cold air blower is operated to perform the thawing schedule with cold air, and then all the thawing schedules are finished when the predetermined surface temperature is observed, and the temperature of the inside without melting the freezing state of the surface Realizes thawing and heating with little difference.

[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 a frozen food which is an object to be heated, and 3 is a turntable 3 on which it is rotated. The turntable 3 is connected to a turntable rotation motor 6 via a support 4 and a rotary shaft 5. Reference numeral 7 is a high frequency oscillator as a heat energy generating means. This high frequency oscillator 7
The high-frequency radio waves oscillated from the
Is excited into the heating chamber 1 to heat the food 2. A cold air blowing source 11 including a cold air generating device, a fan, a motor, etc. is attached near the heating chamber side wall surface 10 to blow cold air to the surface of the food 2 via the punching portion 12. The cool air generator 11 is equipped with a cooling element utilizing the Peltier effect, and the temperature is minus 2 to minus 5 ° C.
A small amount of cold air is sent into the heating chamber 1.

A radiation infrared detector 1 is provided above the heating chamber 1.
3, a chopper 14, and a chopper rotation motor 15 are attached, and a shutter 17 for opening and closing an opening 16 on an optical path connecting the radiant infrared detector 13 and the food 2 (the drive unit is not shown, and is opened in FIG. 1). (Indicating the state) is attached, and these are used to detect the food surface temperature 18
Is configured. The detection surface of the radiant infrared detector 13 is attached downward, and the infrared radiant energy emitted from the food 2 placed on the turntable 3 is transferred to the opening 16 formed in the ceiling surface 19 of the heating chamber 1. It is configured to detect through the shutter 17.

In this structure, the infrared rays radiated from the food 2 are chopped by the chopper 14 and input to the radiation infrared detector 13. Then, the radiant infrared detector 13 outputs a voltage corresponding to the difference between the temperature of the chopper 14 and the temperature of the food 2. That is, the chopper 14
A chopper temperature detecting means (not shown) is provided in the vicinity of the surface temperature detecting circuit for correcting the analog signal of the differential voltage output from the radiant infrared detector 13 based on the output of the chopper temperature detecting means. Send to 21. The temperature detection signal of the surface temperature detection circuit 21 is converted into a digital signal by the A / D converter 22 and sent to the finish judging means (hereinafter abbreviated as microcomputer) 20 including a microcomputer. In FIG. 1, reference numeral 23 is a power source as an electric energy supply means, and 24 is a switch for the user to input the type of heated food and the heating mode to the microcomputer 20. Reference numeral 25 denotes a timer unit as a heating time measuring means, which sends a timer signal to the microcomputer 20. Reference numeral 26 denotes a heating control means for controlling the turntable rotation motor 6, the high frequency oscillator 7, the chopper rotation motor 15, and the cold air blower 11 in accordance with a command from the microcomputer 20.

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 curve 27 indicates that the surface temperature Tc of the frozen food gradually increases from the surface temperature To at the start of heating.
3 shows the change in surface temperature until the end of thawing. This surface temperature change is realized by the following heating schedule.

First, frozen food 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 13. Then, the surface temperature is measured while heating the food 2 at a high frequency, and the temperature rising rate is calculated by the microcomputer 20. 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. Up to this stage, the temperature rises in parallel with the surface temperature of the food, and the temperature unevenness is small. This surface temperature Ta is the first thawing finish judgment temperature during heating, and after this Ta, the thawing condition is changed, and the thawing schedule by high frequency heating is intermittent heating by turning on and off the high frequency oscillator, and a slow thawing schedule. On the other hand, while cooling air is blown into the heating chamber 1 from the cold air blowing source 11, heating is performed while preventing partial overheating due to high frequency heating, especially abnormal temperature rise on the food surface, and then radiant infrared ray detection. Bowl 13
When the predetermined surface temperature Tc is detected, it is determined that the thawing schedule is completed.

In FIG. 2, Tb is an index surface temperature for switching the cold air blowing schedule, and the cold air temperature, air velocity, air volume, etc. are switched according to the type and quantity of food. Further, Tz indicates a surface temperature of 0 ° C., and
tc is a heating time.

Next, FIG. 3 shows an example of the microcomputer control software in the high frequency heating apparatus of this embodiment, and FIG. 4 shows an example of the relationship between the 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 13.
Defrosting is performed according to the heating and cooling air blowing schedule from the time when the temperature rises to a predetermined temperature, and it is determined that the defrosting is completed at the surface temperature Tc, and the heating source and the blowing source are controlled.

[0020]

As described above, according to the present invention, when the rising speed of the surface temperature of the frozen food detected by the surface temperature detecting means reaches a predetermined value, the cool air blower is operated and the surface temperature is increased. When the surface temperature of the frozen food detected by the detection means reaches a predetermined value, the thawing schedule by the heat energy generating means and the cold air blower is finished, so the temperature of the inside without melting the food surface It has become possible to perform excellent thawing without unevenness.

[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 food surface temperature and a control schedule according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 2 Food 7 Thermal energy generating means (high frequency oscillator) 11 Cold air blowing source 18 Food surface temperature detecting means 23 Finish determination means (microcomputer) 26 Heating control means 27 Characteristic curve

Claims (1)

[Claims] 1. A heating chamber (1) for storing a frozen food (2), a heat energy generating means (7) for high-frequency heating the frozen food in the heating chamber, and a surface temperature of the food during cooking. Surface temperature detecting means for detecting (18), a cool air blowing device (11) for blowing cold air into the heating chamber, and a rising speed of the surface temperature of the frozen food detected by the surface temperature detecting means is predetermined. When the surface temperature of the frozen food detected by the surface temperature detecting means reaches a predetermined value while operating the cold air blowing device, the heating by the thermal energy generating means and the cold air blowing device And a control means (20, 26) for terminating the thawing schedule for cooling by the high-frequency heating apparatus.