JPH09243095A - Heating cooking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of dewing on a printed circuit of a control block at the time of heating in a heating cooking device. SOLUTION: A heating cooking device comprises a heating chamber 1, a heater mounted in the heating chamber 1, a magnetron 5 which feeds high frequency waves into the heating chamber 1, a cooling fan 8 disposed in a space 6 outside of the heating chamber 1 for cooling the magnetron 5, and a control block 13 which is constructed such that electronic components 12 are arranged on a printed circuit 10. The heating cooking device further includes a vapor detecting block on the printed circuit 10 which outputs a signal to operate the cooling fan 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing the occurrence of dew condensation on the surface of a printed circuit board which constitutes a control unit in a cooking apparatus such as a microwave oven.

[0002]

2. Description of the Related Art In a microwave oven, when food is heated in a heating chamber, steam from the food may leak out of the heating chamber through a ventilation hole in a wall of the heating chamber.

[0003]

A printed circuit board constituting a control unit is arranged at a position near one of the above-mentioned vent holes outside the heating chamber, that is, at a position in front of the space outside the heating chamber. If condensation occurs due to steam, this causes insulation failure.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent the occurrence of dew condensation on the printed circuit board of the control unit during heating.

[0005]

According to a first aspect of the present invention, there is provided a heating and cooking apparatus provided with a control unit configured by arranging electronic components on a printed circuit board in an outer space of a heating chamber. A water vapor detection unit is formed on the substrate, and a dew condensation prevention fan that blows air to the printed circuit board side by the output of the water vapor detection unit is provided.

According to the above construction, when the steam leaks out of the heating chamber to reach the vicinity of the printed circuit board during heating, the dew condensation preventing fan is operated by the output of the steam detection unit, and an air flow is generated in the vicinity of the printed circuit board. The water vapor is moved, which prevents dew condensation on the printed circuit board surface.

According to the second aspect of the present invention, the heating chamber, the heater provided in the heating chamber, the magnetron for supplying high frequency into the heating chamber, and the cooling fan provided in the space outside the heating chamber for cooling the magnetron. In a heating and cooking device provided with a control unit configured by arranging electronic components on a printed circuit board, a water vapor detection unit is formed on the printed circuit board, and the cooling fan is operated by the output of the water vapor detection unit. It has a configuration.

According to the above construction, when water vapor leaks out of the heating chamber and reaches the vicinity of the printed circuit board when heated by the operation of the heater, the cooling fan is operated by the output of the water vapor detection section to generate an air flow in the vicinity of the printed circuit board. Then, the water vapor is moved, which prevents the occurrence of dew condensation on the printed circuit board surface. When the magnetron is heated, the cooling fan is activated to cool the McNetron, etc., so that the air flow does not cause condensation on the printed circuit board.However, when the heater is activated, the cooling fan does not operate, so condensation occurs. This makes it easy to prevent the occurrence of dew condensation.

According to the third aspect of the present invention, the water vapor detection unit is composed of a pair of resistance detection patterns that are closely arranged so that the resistance value between water vapor decreases when water vapor exists.

According to the above construction, the resistance value between the resistance detection patterns is reduced by the water vapor, and this reduction is transmitted to the control unit. Further, according to the above configuration, the water vapor detection unit can be obtained with a simple configuration by forming the pattern on the printed circuit board that constitutes the control unit.

According to a fourth aspect of the invention, the cooling fan is configured to be operated weakly or intermittently.

According to the above construction, since the cooling capacity of the cooling fan is low at the time of preventing dew condensation when the heater is operating, the temperature of the heating chamber does not decrease and the heating capacity of the heater does not decrease.

[0013]

1 is a schematic plan view of a microwave oven as a heating and cooking apparatus of the present invention, and FIG. 2 is a simplified side view of the structure.

Reference numeral 1 denotes a heating chamber, a door 2 is provided on the front surface thereof, and two heaters 3 are provided above the heating chamber 1.
Further, a magnetron 5 for supplying a high frequency into the heating chamber 1 is provided above the side wall 4 on one side of the heating chamber 1.
In a side space 6 as an outer space of the heating chamber on one side of the heating chamber 1, a magnetron 5 is positioned so as to project above it, and a high-voltage transformer 7 that supplies power to the magnetron 5 is provided below the magnetron 5. Further, a cooling fan 8 as a dew condensation preventing fan for cooling the magnetron 5 and the high-voltage transformer 7 is provided at the rear part. At the rear position of the operation panel 9 in the front part in the side space 6, an electronic component 12 is arranged on a printed circuit board 10 and a control part 13 is provided. Further, ventilation holes 16 are provided at front and rear positions of both side walls 4 of the heating chamber 1, and the ventilation holes 16 provided at the front position are located near the upper portion of the printed circuit board 10.

As shown in FIG. 3, a pair of resistance patterns 19 are provided at the upper part of the printed circuit board 10 so as to enter through a small gap 18, and the resistance value between the resistance patterns 19 decreases in the presence of water vapor. A water vapor detection unit 17 is additionally provided.

FIG. 4 shows the electrical connection structure of the water vapor detection unit 17. One of the resistance patterns 19 is connected to the resistance 20 and the divided voltage is applied to the control unit 13 including a microcomputer. Then, when water vapor is present and the resistance value between the resistance patterns 19 decreases, and the divided voltage exceeds the set value, a drive signal is supplied from the control unit 13 to the cooling fan 8. Then, the drive signal at that time is given so that the cooling fan 8 is operated weakly or intermittently.

The operation will be described below. The solid and dotted arrows in FIGS. 1 and 2 indicate the flow of air during operation of the cooling fan 8, and the air sucked from the intake hole 21 of the casing 22 by the cooling fan 8 flows in the vicinity of the magnetron 5 and the high-voltage transformer 7. It hits the surface of the printed circuit board 10 and enters the heating chamber 1 through the ventilation hole 16 of the side wall 4. Furthermore, the opposite side wall 4
Through the ventilation hole 16 to the outside of the heating chamber 1 and is discharged to the outside from the exhaust hole 23 of the casing 22.

When the magnetron 5 is operated, the magnetron 5 and the high-voltage transformer 7 are cooled by the flow of air, and the steam in the heating chamber 1 is exhausted to the outside through the door 2. The heating state of the food in the heating chamber 1 can be confirmed.

On the other hand, when the heater 3 is operated, the cooling fan 8 is not operated at first, but when the heating progresses to a certain degree, the steam generated from the food is ventilated in the vent hole 1 of the side wall 4.
Leak into the side space 6 through 6. This allows
Printed circuit board 1 located near one of the vent holes 16
The resistance value between the resistance patterns 19 of 0 decreases, and the water vapor detection unit 17 outputs to operate the cooling fan 8 and the above-described air flow to cause the printed circuit board 1
Water vapor near 0 is moved. As a result, dew condensation due to water vapor adhesion on the printed circuit board 10 surface is prevented in advance.

Since the operation of the cooling fan 8 during the operation of the heater 3 is only for the movement of the water vapor in the vicinity of the printed circuit board 10, it is satisfied by the weak operation or the intermittent operation. Even if the air circulates in the heating chamber 1 due to the weak operation or the intermittent operation, the cooling in the heating chamber 1 is minimized, and the deterioration of the heating capacity of the heater 3 is suppressed as much as possible.

[0021]

According to the present invention, it is possible to prevent dew condensation on the printed circuit board surface of the control section during heating, thereby preventing insulation failure on the printed circuit board, stable operation, and excellent safety. A cooking device is obtained.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a heating and cooking apparatus of the present invention.

FIG. 2 is a schematic side view of the heating and cooking device of the present invention.

FIG. 3 is a configuration diagram of a water vapor detection unit

FIG. 4 is a diagram showing electrical connection of a water vapor detection unit.

[Explanation of symbols]

 1 Heating Chamber 3 Heater 5 Magnetron 6 Side Space (Outside Space of Heating Chamber) 8 Cooling Fan (Dew Condensation Prevention Fan) 10 Printed Circuit Board 12 Electronic Components 13 Control Section 17 Water Vapor Detection Section

Claims (4)

[Claims] 1. A heating and cooking apparatus comprising a control unit configured by arranging electronic parts on a printed circuit board in an outer space of a heating chamber, wherein a water vapor detection unit is formed on the printed circuit board and the steam detection is performed. A heating and cooking apparatus comprising a dew condensation preventing fan that blows air to the printed circuit board side according to the output of the unit. 2. A heating chamber, a heater provided in the heating chamber, a magnetron for supplying a high frequency to the heating chamber, a cooling fan provided in an outer space of the heating chamber for cooling the magnetron, and an electronic component on a printed circuit board. In a heating and cooking apparatus provided with a control unit configured by arranging the heating unit, a steam detecting unit is formed on the printed circuit board, and the cooling fan is operated by the output of the steam detecting unit. Cooking equipment. 3. The heating according to claim 1, wherein the water vapor detection unit is composed of a pair of resistance detection patterns that are closely arranged so that the resistance value therebetween decreases when water vapor is present. Cooking equipment. 4. The cooking apparatus according to claim 2, wherein the cooling fan is operated weakly or intermittently.