JPH07177963A - Rice cooker - Google Patents

Abstract

PURPOSE:To provide a safe controller for the rice cooker so as to prevent any non-safe mode of tracking or the like from being generated on a substrate even when liquid such as water enters the main body of the rice cooker. CONSTITUTION:Both a heating driving circuit 3 for driving a heating means 2 to heat an inner pot 1 and a control circuit 4 for controlling this heating driving circuit 3 are mounted on a printed wiring board 5, and the upper face of the printed wiring board 5 is coated with a coating member 6. This coating member 6 is gradually lowered toward the peripheral edge part of the printed wiring board 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker used in ordinary households.

[0002]

2. Description of the Related Art In recent years, a rice cooker controlled by a microcomputer has become the mainstream of the market, and it has been controlled so that an ideal rice cooked from old times such as choro choro middle papa can be produced. In addition, a rice cooker that uses the IH heater system that applies the principle of induction heating as a heating source and that makes the rice more delicious with higher power than the conventional sheathed heater system has also attracted attention in the market.

[0003]

However, the rice cooker is a product that handles water, and in particular, when water is applied to a control device having a high-voltage generating circuit, current leakage may occur, or in the worst case, ignition may occur. It had to be assumed, and there was a problem in terms of safety.

The present invention solves the above-mentioned conventional problems, and it is a first object of the present invention to provide a rice cooker capable of ensuring safety even if liquid such as water is applied to the component side of a printed wiring board. It is intended.

A second object of the present invention is to provide a rice cooker capable of ensuring safety even if a liquid such as water dripping on the component side of the printed wiring board gets around to the copper foil side of the printed wiring board. To do.

[0006]

In order to achieve the first object, the present invention provides an inner pot for containing rice, a heating means for heating the inner pot, and a heating drive for driving the heating means. A coating circuit, a control circuit that controls the heating drive circuit to control rice cooking, a printed wiring board on which the heating drive circuit and the control circuit are mounted, and a coating material that covers the upper surface of the printed wiring board. The material is formed so that its height is lowered toward the peripheral portion of the printed wiring board.

In order to achieve the second object, the present invention provides a high-voltage part copper foil and a low-voltage part copper foil provided on a printed wiring board, and a high-voltage part copper foil and a low-voltage part copper foil. And a coating material provided between them.

[0008]

With the above means, even if a liquid such as water drops or scatters around the parts where the peak value of the applied voltage on the printed wiring board is 50 V or more, the liquid is drained from the substrate, so that tracking or the like is prevented. Does not happen.

Further, when the coating material is provided between the high-voltage copper foil and the low-voltage copper foil, the short-circuit phenomenon between the copper foils does not occur, which also prevents the tracking and the like.

[0010]

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

Reference numeral 1 is an inner pot for containing rice or the like, 2 is heating means for heating the inner pot 1, 3 is a heating drive circuit for driving the heating means 2, 4 is control for controlling the heating drive circuit 3 to control rice cooking. Circuits 5 are printed wiring boards on which the heating drive circuit 3 and the control circuit 4 are mounted. 6 is a coating material, which is applied on the component side of the printed wiring board so as to cover a part or more of the periphery of the component where the peak value of the applied voltage is 50 V or more, and to form a drainage path on the surface thereof.

FIG. 2 is a circuit diagram for explaining an embodiment of the present invention. 1 is an inner pot for containing rice or the like, 7 is a heating coil for heating the inner pot 1, 8 is a heating coil 7, An inverter circuit that includes a resonance capacitor 9, a switching element 10, and a damper diode 11 and supplies a high-frequency current to the heating coil 7, 12 is a rectifier that rectifies the commercial power supply 13 into direct current, and 14 is an input capacitor that smoothes the output of the rectifier. Further, 15 is a microcomputer (hereinafter referred to as a microcomputer), 16 is an inverter drive circuit for giving a drive signal to the switching element 10, 17 is an input circuit for giving input information to the microcomputer 15 by a key switch or the like, 18 is an LED indicating an operating state, A notification circuit for displaying / notifying by a display element such as an LCD or a buzzer, and 19 is a control circuit including a microcomputer 15, an inverter drive circuit 16, an input circuit 17, and a notification circuit 18.

FIG. 3 is a sectional view of a rice cooker showing an embodiment of the present invention, in which 20 is an inverter circuit 8 excluding the heating coil 7,
An inverter board on which the rectifier 12 and the input capacitor 14 are mounted, 21 is a control board on which the control circuit 19 is mounted, and the printed wiring board is composed of the inverter board 20 and the control board 21.

In FIG. 4, the coating material 22 is A-
As can be seen from the cross section A, when the inverter board 20 is placed horizontally, the surface of the coating material 22 is inclined so as to gradually lower toward the end surface (left side in the drawing) of the inverter board 20.

FIG. 5 illustrates the second embodiment and is an external view of the inverter board 20 as viewed from the copper foil side. Here, the coating material 23 is applied in a strip shape so as to separate the high voltage portion copper foil 24 and the low voltage portion copper foil 25 on the copper foil side of the inverter board 20.

Next, the operation of this structure will be described with reference to FIG.
~ It demonstrates using FIG. When the user inputs information from the input circuit 17 to the microcomputer 15, the microcomputer 15 notifies the state by the notification circuit 18 and causes the inverter drive circuit 16 to oscillate the inverter circuit 8. When the inverter circuit 8 oscillates, a high frequency current is supplied to the heating coil 7 to heat the inner pot 1. At this time, between the heating coil 7 side terminal of the switching element 10 and the ground terminal, about 140 V (when the commercial power supply voltage is 100 V) is generated while the inverter is not oscillating, and a high voltage of 600 V or more is generated during the oscillation. There is. Here, the inverter drive circuit 16
Is controlled according to a rice cooking sequence pre-programmed in the ROM of the microcomputer 15 to perform ideal rice cooking.

Here, the inverter circuit 8 (heating coil 7
The inverter board 20 on which the parts are mounted on the bottom of the product body is placed on the lower side of the product body because most of the inverter circuit 8 is composed of heavy parts as shown in FIG. 3 and due to the structural space of the rice cooker. In many cases, it is installed horizontally with it placed on top. In addition, since rice cookers are often used around the water in the kitchen, etc., if the product is splashed with water or spills during cooking, the liquid may easily enter the body of the rice cooker. You have to assume. Therefore,
Assuming that the liquid is dropped or scattered so that the high voltage part and the low voltage part on the inverter board 20 are short-circuited, the interposition of the liquid causes tracking on the board and a current leak occurs. When this state progresses, a spark occurs, and when a discharge path is formed, a flying phenomenon eventually occurs.

Therefore, as shown in FIG. 4, the coating material 22 is applied to the periphery of the high voltage applying component of the inverter board 20, and the surface of the coating material 22 is directed toward the end surface of the inverter board 20 (leftward in the drawing). The drainage path is formed by inclining so as to gradually lower, and the liquid flows to the end surface of the substrate according to the inclination of the surface of the coating material 22, so that an unsafe mode such as tracking does not occur.

Furthermore, as shown in FIG. 5, a strip-shaped coating material 23 is provided so as to separate the high-pressure part copper foil 24 and the low-voltage part copper foil 25 from the liquid that has flown around the back surface (copper foil side) of the substrate.
As a result, a short circuit phenomenon between the high voltage part and the low voltage part can be avoided, so that an unsafe mode such as tracking cannot be reached. At this time, since the copper foil portion is not covered with the coating material, heat radiation from the copper foil portion is not hindered.

The tracking level differs depending on the operating state of the equipment, the distance between the parts or the copper foil, the type of the dropped liquid (presence or absence of electrolyte), etc.
There is a great risk of occurrence in the above high-pressure portion, and it is effective to apply the configuration of the present invention.

In the present embodiment, the IH heater type rice cooker has been described. However, it is needless to say that the same effect as above can be obtained by adopting the same configuration for the sheath heater type rice cooker. .

[0022]

As is apparent from the above-described embodiments, the present invention allows the liquid such as water to be dripped or scattered around the parts where the peak value of the applied voltage on the printed wiring board is 50 V or more.
Since the liquid is drained from the substrate along the drainage path on the surface of the coating material, it does not cause tracking and is safe.

Further, when a coating material is provided between the high-voltage side copper foil and the low-voltage portion copper foil provided on the printed wiring board, a short circuit phenomenon between these copper foils can be avoided and tracking does not occur. Moreover, since the copper foil is not covered with a coating material, it can provide an extremely safe rice cooker without hindering heat radiation from the copper foil, and its industrial value is great. It is a thing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a rice cooker according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing the rice cooker according to the first embodiment of the present invention.

FIG. 3 is a sectional view of the rice cooker showing the first embodiment of the present invention.

FIG. 4A is a partial plan view of a printed wiring board of the rice cooker according to the first embodiment of the present invention, and FIG. 4B is a sectional view taken along the line AA of the board.

FIG. 5 (a) is a partial plan view of a printed wiring board of a rice cooker according to a second embodiment of the present invention (b) is a sectional view taken along line BB of the board.

[Explanation of symbols]

 1 Inner pan 2 Heating means 3 Heating drive circuit 4 Control circuit 5 Printed wiring board 6, 22 Coating material

Claims (2)

[Claims] 1. An inner pot containing rice or the like, a heating means for heating the inner pot, a heating drive circuit for driving the heating means, and a control circuit for controlling the heating drive circuit to control rice cooking. The printed wiring board on which the heating drive circuit and the control circuit are mounted, and the coating material that covers the upper surface of the printed wiring board are provided, and the coating material is lowered in height toward the peripheral portion of the printed wiring board. Rice cooker. 2. The high-voltage part copper foil and the low-voltage part copper foil provided on the printed wiring board, and the coating material provided between the high-voltage part copper foil and the low-voltage part copper foil. Rice cooker.