JPH0579637A - Cooker - Google Patents

Abstract

PURPOSE:To enhance the detection performance of a steam detection means used for microwave ovens. CONSTITUTION:A microwave oven is provided with a detection means 11 to detect steam exposed in an atmosphere of a heating chamber which runs through an exhaust duct and controls the heating based on the output of the detection means 11. A bead type thermistor 13 is bonded to a sheet-like metal plate 12 with tape 14 in such a fashion that they may come into close contact with each other, thereby forming the detection means 11. This construction makes it possible to maintain the amount of heat dissipated from the thermistor 13 at a specified value and hence enhance the detection performance of the detection means 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooking device such as a microwave oven.

[0002]

2. Description of the Related Art In the cooking device disclosed in Japanese Patent Application Laid-Open No. 2-306024, a heating means is controlled by detecting atmosphere information in the heating chamber, that is, steam, by a detecting means composed of a pyroelectric element. However, in this detection means, due to the piezoelectricity of the pyroelectric element, the cooking device is erroneously affected by vibration and shock,
Further, when used for a long time in a high temperature state, the polarization of the pyroelectric element deteriorates.

On the other hand, if the detection means is replaced by a pyroelectric element and a bead type thermistor is adhered to a metal plate, it is difficult to keep the amount of adhesive used constant, and the amount of heat released by the thermistor is desired. There is a problem that the value cannot be maintained and the detection performance of the detection means cannot be improved.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cooker with improved detection performance of a detection means formed by fixing a bead type thermistor to a metal plate.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a thin metal plate in a cooking device which is provided with a detecting means for detecting the atmosphere information which is exposed to the atmosphere of a heating chamber, and which controls heating based on the output of the detecting means. The above-mentioned detection means is formed by sticking a bead-type thermistor to the tape in a close contact state with a tape.

[0006]

By adhering the bead type thermistor to the thin metal plate in a close contact state with tape, the amount of heat radiated from the thermistor to the metal plate can be maintained at a desired value, and the detection performance of the detection means is improved.

[0007]

1 shows the structure of a microwave oven according to an embodiment of the present invention. A heating chamber 1 is provided inside the microwave oven. In the heating chamber 1, the food 4 on the turntable 3 is heated by the microwave supplied from the magnetron 2 and a halogen heater or the like (not shown). ) Is also performed by radiant heat from.

A cooling fan 5 is provided behind the magnetron 2, and by driving the cooling fan 5,
Outside air is sucked in from the rear air intake holes 6, 6, ... And cooling air is supplied to the magnetron 2. The cooling air after cooling the magnetron enters the heating chamber 1 through the intake holes 7, 7 ... In front of the right side wall of the heating chamber, and moves toward the rear side of the left side wall of the heating chamber along with an atmosphere containing steam generated from food in accordance with heating. Are exhausted to the outside through the exhaust holes 8, 8 ... of the heating chamber and to the outside through exhaust ducts 10 from the exhaust holes 9, 9 ... A part of the exhaust duct 10 is exposed to the atmosphere in the heating chamber passing through the exhaust duct 10 together with the cooling air, and is formed by the detection means 11 for detecting information of this atmosphere, that is, vapor.

Details of the detecting means 11 are as shown in FIGS. A thin metal plate 12 made of 42 alloy and having a thickness of 0.1 mm is provided.
A recess is formed in the vicinity of the center of the outer surface (outside of the exhaust duct), and a bead type thermistor 13 having a small time constant of 1 second or less is positioned in the recess. The thermistor 13 is a heat-resistant polyimide tape 14 having a thickness of several 10 μm.
Is adhered to the metal plate 12 in the recessed state.
Both ends of the tape 14 are folded back to the inner surface of the metal plate 12 (inside the exhaust duct), and are difficult to peel off. The lead wire 15 of the thermistor 13 is fastened and fixed together with a binder 17 to a protruding portion 16 integrally formed with the metal plate 12.

FIG. 4 shows a circuit including the detecting means 11 described above. A resistor 18 is connected in series to the thermistor 13 of the detecting means 11, and the variation of the voltage Vs at the connection point between the thermistor 13 and the resistor 18 is an AC amplifier. Amplified by 19 and output Vo
Is obtained. This output Vo is input to the microcomputer 20 having a built-in A / D converter.

In this case, the detecting means 11 is
At the beginning of heating, the atmosphere inside the heating chamber passing through the exhaust duct 10 is in a dry state, the latent heat (heat capacity) is small, and the fluctuation of the voltage Vs is small. Then, referring to the characteristic of the output Vo according to the output of the detecting means 11 shown in FIG. 5, the output Vo in the range a is slightly fluctuated due to the influence of noise. Heating progresses, steam is generated from food, and exhaust duct 10
When the atmosphere inside the heating chamber passing through the interior contains steam, the latent heat of the steam causes the metal plate 12 of the detection means 11 to temporarily rise in temperature, and the temperature change is transmitted to the thermistor 13 to raise the temperature in the thermistor 13. The voltage Vs temporarily drops and the output Vo temporarily rises. The increase in the output Vo increases as the amount of steam increases. Microcomputer 20
Controls the heating by driving the magnetron 2 and the halogen heater based on the output Vo corresponding to the output of the detecting means 11, and ends the heating when the output Vo exceeds a preset level VE.

In the above structure, since the thermistor 13 is in close contact with the metal plate 12, the amount of heat radiated from the thermistor 13 to the metal plate 12 can be maintained at a desired value, and the detection performance of the detection means 11 is improved. is doing. Tape 1
As for the amount of heat radiation due to No. 4, the thickness of the tape 14 can be easily managed, so that the desired value can be maintained. Further, in the detection means 11, the outer surface of the metal plate 12 is directly contacted by the cooling air from the cooling fan 5 and is actively cooled, so that the sensitivity is improved.

[0013]

According to the cooker of the present invention, the bead type thermistor is fixed to the metal plate to form the detecting means, and the thermistor is adhered to the metal plate with the tape. There is no need to dispose an adhesive between the thermistor and the metal plate, the amount of heat radiated from the thermistor to the metal plate can be maintained at a desired value, the detection performance of the detection means can be improved, and a stable finished state can be obtained. it can.

Further, since the thickness of the tape can be easily controlled, the amount of heat radiated by the tape can be maintained at a desired value, and in this respect also, the detection performance of the detection means can be improved and a stable finished state can be obtained.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a microwave oven according to an embodiment of the present invention.

FIG. 2 is a front view of a detection unit of the microwave oven.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a circuit diagram of a main part of the microwave oven.

5 is a characteristic diagram of the output Vo in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 11 Detection means 12 Metal plate 13 Bead type thermistor 14 Tape

Claims (1)

[Claims] 1. A cooker for controlling heating based on an output of the detection means provided with a detection means which is exposed to the atmosphere of the heating chamber and detects the atmosphere information, and a bead type thermistor taped on a thin metal plate. The cooking device is characterized in that the above-mentioned detection means is formed by sticking it in close contact with.