JP2975767B2 - Cooking device - Google Patents

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 a cooker disclosed in Japanese Patent Application Laid-Open No. Hei 2-306024, heating information is controlled by detecting atmosphere information, that is, steam, in a heating chamber by a detecting means including a pyroelectric element. However, in this detection means, due to the piezoelectricity of the pyroelectric element, the cooker is liable to malfunction due to the influence of vibration and shock.
In addition, when the pyroelectric element is used for a long time at a high temperature, the polarization of the pyroelectric element is deteriorated.

On the other hand, if the detecting means is of a structure in which a bead-type thermistor is bonded to a metal plate instead of a pyroelectric element (Japanese Patent Application No. 3-175111), it is resistant to vibration and impact and can be used at high temperatures. On the other hand, it is difficult to keep the amount of adhesive used constant, so that the heat conduction performance between the metal plate and the thermistor cannot be stably maintained at a desired value, and the detection means must obtain stable detection performance. However, there is a problem that mass production is difficult.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve a detecting means for detecting atmosphere information by a thermistor so as to stabilize the detecting performance of the detecting means and to facilitate mass production of the detecting means.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a cooking device which is provided with a detecting means for detecting atmospheric information exposed to the atmosphere of a heating chamber and controlling heating based on the output of the detecting means. The above-mentioned detecting means is formed by soldering a chip type thermistor to the above.

Further, copper foil is applied entirely to one surface of the printed circuit board, and the chip type thermistor is soldered to the other surface, and one surface of the printed circuit board is exposed to the atmosphere.

[0007]

The atmosphere in the heating chamber, that is, the latent heat of the steam is instantaneously transmitted to the chip type thermistor via the thin printed circuit board, and the detection means detects the steam. In this case, the chip type thermistor is to be soldered to a printed circuit board, and the soldering area is limited to a non-resist film portion and is constant, and the heat conduction between the thermistor and the printed circuit board is constant. Performance is stably maintained at the desired value,
The detection means has stable detection performance and is easily mass-produced.

Further, the printed circuit board absorbs the latent heat of the steam well by the copper foil provided on the entire surface exposed to the atmosphere of the heating chamber, and the steam detecting sensitivity of the detecting means is improved. Further, the chip type thermistor is soldered to the other surface of the printed circuit board, so that it is not easily exposed to the atmosphere of the heating chamber, and insulation failure does not occur.

[0009]

1 and 2 show 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 microwaves supplied from a magnetron 2, and a halogen heater or the like (not shown) The heating is also performed by the radiant heat from ()).

[0010] A cooling fan 5 is provided behind the magnetron 2.
Outside air is sucked in from the rear intake holes 6, 6... And cooling air is supplied to the magnetron 2. The cooling air after magnetron cooling enters the heating chamber 1 through the intake holes 7, 7... Near the right side wall of the heating chamber, and is exhausted from the left side wall of the heating chamber with an atmosphere including steam generated from food as the heating is performed. Hole 8, 8,
.. Are discharged to the outside, and a small amount is partially discharged to the outside of the heating chamber through a small number of exhaust holes 10, 10,.

With respect to the exhaust holes 10, 10,...
An exhaust duct 13 formed from a heating chamber upper wall 9, a microwave oven upper wall 11, and a packing 12 is provided.
Further, a small exhaust duct 14 is provided in the exhaust duct 13 so as to specifically surround the exhaust holes 8, 8,. The exhaust duct 13 guides a part of the cooling air from the cooling fan 5 to the exhaust holes 10, 10,... And then to the cooling fan 5 according to the action of the suction force of the cooling fan 5. And such an exhaust duct 13
A small amount of wind accompanying the atmosphere containing steam from food is drawn by the cooling air flow in the inside of the exhaust holes 10, 10.
From the cooling air in the exhaust duct 13 through the small exhaust duct 14.

A part of the upper wall of the small exhaust duct 14 is formed by the detecting means 15. The detecting means 15 is exposed on one side, that is, the lower surface, to the atmosphere in the heating chamber passing through the inside of the small exhaust duct 14, and detects information on the atmosphere, that is, the vapor. The other surface, that is, the upper surface, is exposed to cooling air passing through the exhaust duct 13.

The details of the detecting means 15 are as shown in FIGS. 0.5 thickness made of glass epoxy plate
A thin printed board 16 having a thickness of about 0.8 mm is provided. The lower surface of the printed board 16 is provided with a copper foil 17 over the entire surface as shown in FIG.
The copper foils 18 and 19 are applied in two wide areas. The entire surface of the copper foil 17 on the lower surface side is protected by a thin resist film, and the copper foils 18 and 19 on the upper surface side are also covered with the resist film except for small regions 20 and 21 near the center of the printed circuit board 16. I have. In addition, these copper foils 1
Lead wires 22 and 23 are connected to the ends of 8 and 19, respectively. Then, 2 near the center of the upper surface of the printed circuit board 16
Chip thermistors 24 are soldered to the small areas 20 and 21 of the two copper foils 18 and 19 over the small areas.

FIG. 5 shows a circuit including the detecting means 15. The resistor 25 is connected in series to the thermistor 24 of the detecting means 15. The fluctuation of the voltage Vs at the connection point between the thermistor 24 and the resistor 25 is determined by the capacitor 26. Then, the DC component is removed, and the signal is amplified by the AC amplifier 27 to obtain the output Vo. This output Vo is input to a microcomputer 28 having a built-in A / D converter.

In this case, in the detecting means 15,
At the beginning of heating, the atmosphere in the heating chamber passing through the small exhaust duct 14 is in a dry state, has a small latent heat (heat capacity), and has a small fluctuation in the voltage Vs. Then, the detecting means 15 shown in FIG.
With reference to the characteristic of the output Vo corresponding to the output of the above, the output Vo in the range a slightly fluctuates due to the influence of noise. When the heating proceeds and steam is generated from the food and the atmosphere in the heating chamber passing through the small exhaust duct 14 contains the steam, the latent heat of the steam causes the printed circuit board 16 of the detection means 15 to temporarily rise in temperature and the thermistor 24, the temperature change is instantaneously transmitted, the temperature of the thermistor 24 rises, the voltage Vs temporarily drops, and the output Vo temporarily rises. Output Vo
Increases as the amount of steam increases. The microcomputer 28 controls the heating by driving the magnetron 2 and the halogen heater based on the output Vo corresponding to the output of the detection means 15, and terminates the heating when the output Vo exceeds a preset level VE. .

Now, in such a configuration, the thermistor 24 is soldered to the printed board 16,
The soldering area is limited to the small regions 20 and 21 which are non-resist film portions and is constant.
The heat conduction performance between the printed circuit board 4 and the printed circuit board 16 can be stably maintained at a desired value, and the detection performance of the detection means 15 is stable, and mass production is easy. Further, the printed circuit board 16 has a copper foil 17 provided on the entire lower surface on the side exposed to the atmosphere of the heating chamber.
Absorbs the latent heat of the steam well,
Has improved steam detection sensitivity. In addition, the thermistor 24 is soldered to the upper surface of the printed circuit board 16 and is not easily exposed to the atmosphere of the heating chamber, and does not cause insulation failure or the like.

[0017]

According to the cooking device of the present invention, in the configuration having the detecting means for detecting the atmosphere information by the thermistor,
This detecting means is formed by soldering a chip type thermistor to a thin printed circuit board, whereby the heat conduction performance between the thermistor and the printed circuit board can be stably maintained at a desired value. And the detection means can be easily mass-produced.

Further, copper foil is applied entirely to one surface of the printed circuit board, and the chip type thermistor is soldered to the other surface, so that one surface of the printed circuit board is exposed to the atmosphere. Thereby, the vapor detection sensitivity of the detection means can be improved, and the occurrence of insulation failure or the like of the thermistor can be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a plan view of detection means of the microwave oven.

FIG. 4 is a bottom view of the detection means of the microwave oven.

FIG. 5 is a main part circuit diagram of the microwave oven.

FIG. 6 is a characteristic diagram of an output Vo in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating chamber 15 Detecting means 16 Thin printed circuit board 17 Copper foil 24 Chip type thermistor

Claims (1)

(57) [Claims] A cooking device for controlling heating based on an output of the detecting means, wherein the heating means is provided with a detecting means for detecting atmosphere information exposed to the atmosphere of the heating chamber ;
Non-registration on the other side that is not easily exposed to the atmosphere of the above heating room
By soldering the thermistor chips into small areas, which is a part of the bets film, to form the sensing means, the purine
On one side of the substrate exposed to the atmosphere of the heating chamber
It is characterized by applying copper foil that absorbs the latent heat of steam well
Cooker to be.