JP2998435B2 - Microwave oven safety circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relay for driving a high-frequency oscillator on a printed circuit board and a microwave oven comprising a door switch detecting circuit.

[0002]

2. Description of the Related Art FIG. 4 is an example of a circuit diagram of a microwave oven.
It is roughly composed of a main body circuit 1 and a control circuit 2 composed of a printed circuit board. The main body circuit 1 includes a relay 4 for driving a high-frequency oscillator 3 for heating food, a latch switch 5 that operates in conjunction with a door for putting food in and out, and a door switch 6 for generating a signal indicating whether the door is open or closed to the control circuit 2. It consists of

When the commercial power supply is stepped down, the control circuit 2 comprises a transformer 7, a rectifying diode 8 and a smoothing capacitor 9 for producing a power supply for driving the coil of the relay 4, and a regulator 10 for producing a power supply for driving the microcomputer 11. The door switch 6 is connected to both ends, a power supply for a relay is provided on one side of the printed circuit board, and a coil for the relay 4 and a door detection circuit for converting the open / closed state of the door into a voltage recognizable by the microcomputer 11 are provided on one side. It is composed of a connector 12 to be connected.

FIG. 5 shows a part of a pattern diagram of a conventional printed circuit board. The power supply to the relay 4 for driving the high-frequency oscillator is connected to one end of the connector 12 via the pattern 14, from one end to the door switch 6 of the main circuit, and from one side of the door switch 6 to the control circuit. One end of the connector 12 is connected to the relay 4 and the door detection circuit by a pattern 15 from one end.

[0005] With the above configuration, the microwave oven always stops the operation of the high frequency oscillator when the door is opened. The Electrical Appliance and Material Control Law also states that a double safety mechanism is required. In this case, the latch switch 5 and the relay 4 are the safety device.

[0006]

However, in this configuration, considering the environment in which the microwave oven is placed and the environment in which the control circuit is placed, the control circuit is exposed to high temperature and high humidity, water droplets, cockroaches, and other insects and dead bodies. Insulation deterioration between patterns is considered.

When the patterns 14 and 15 shown in FIG. 5 cause insulation deterioration, the supply power of the relay is supplied to the pattern 15 even though the door is opened, and the relay 4 driving the high-frequency oscillator is turned on. It is always ON, and the door detection circuit determines that the door is always closed. When such a phenomenon occurs, the only safety mechanism is the latch switch, and if the latch switch fails, a problem occurs that radio waves are output from the high-frequency oscillator even when the door is opened.

Accordingly, the present invention provides a safety pattern having the same potential as when a door is opened around a door signal pattern extending from a connector on a printed circuit board connected from a door switch to a relay for driving a high frequency oscillator and a door detection circuit. Therefore, even if insulation degradation occurs on the printed circuit board,
A first object is to supply a highly safe microwave oven by always keeping the door open.

A second object is to provide a diode in the middle of the pattern from the connector to the relay for driving the high-frequency oscillator and the door detection circuit, and to consider the contents of the pattern after the diode even if insulation deterioration occurs. It is intended to be.

A third object is to provide a safety pattern having the same potential as when the door is opened around a pattern extending from the connector to a relay for driving a high-frequency oscillator and a door detection circuit. The purpose is to easily realize the design by providing the pins.

[0011]

In order to achieve the first object, the present invention provides a heating chamber for storing food, a high-frequency oscillator coupled to the heating chamber, a door for taking in and out of food, A latch switch and a door switch that operate in conjunction with the door, a connector that is electrically connected to the door switch, is provided on a substrate, and a relay that drives the high-frequency oscillator connected from the connector and the door switch. And a control circuit comprising a door detection circuit for detecting a state, wherein the control circuit has the same potential as when the door is opened around a door signal pattern on a printed circuit board from the connector to the relay and the door detection circuit. The safety pattern is provided.

In order to achieve the second object, a heating chamber for storing food, a high-frequency oscillator for heating food connected to the heating chamber, a door for taking in and out the food, and a door interlocking with the door are provided. A latch switch and a door switch that operate, a connector electrically connected to the door switch, provided on a printed circuit board, a relay for driving the high-frequency oscillator connected from the connector, and detecting a state of the door switch. A control circuit comprising a door detection circuit, the control circuit comprising: a first diode on the way from the connector to the relay; and a second diode B on the way from the connector to the door detection circuit. And providing the diode around a pattern on a printed circuit board from the connector to the first diode and the second diode. A structure having a safety pattern Hirakiji the same potential.

In order to achieve a third object, a heating chamber for storing food, a high-frequency oscillator coupled to the heating chamber, a door for taking food in and out, a latch switch operating in conjunction with the door, and A door switch, a connector electrically connected to the door switch, provided on a printed circuit board, a relay for driving the high-frequency oscillator connected from the connector, and a door detection circuit for detecting a state of the door switch. A control circuit, the control circuit having a safety pattern at the same potential as when the door is opened around a door signal pattern on a printed circuit board from the connector to the relay and the door detection circuit, and the safety pattern is The dedicated pin provided on the connector for connecting the signal of the door switch is connected together with the chassis ground. And butterflies.

[0014]

According to the first aspect of the present invention, there is provided a microwave oven comprising:
Even if insulation deterioration occurs in the printed circuit board, the door is always kept open to improve safety.

[0015] Further, the second configuration reduces a danger area against insulation deterioration and improves safety.

According to the third configuration, it can be easily realized in design by supplying from adjacent pins of the connector.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A safety circuit for a microwave oven according to the present invention will be described below with reference to the drawings. The same parts as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 1 shows a safety circuit of a microwave oven. The power supply to the relay 4 that drives the high-frequency oscillator is connected to one end of the connector 12 via the relay power supply pattern 14, from one end to the door switch 6 of the main circuit, and from one side of the door switch 6 to control. Via one side of the connector 12 on the circuit, the relay 4
And it is connected to the door detection circuit. A safety pattern 16 is provided around the door signal pattern 15. In this case, the potential of the safety pattern 16 is the potential of the door detection circuit when the door is opened, that is, the chassis ground (OV).
Becomes Next, the operation will be described.
May be cut off due to high temperature and high humidity environment or cockroach invasion.
When the edge deterioration occurs, the door signal pattern 15
Short circuit with the provided safety pattern 16,
When the potential of the door detection circuit (OV) when the door is opened
In both cases, the power supply to the relay 4 is cut off. I
Therefore, if the latch switch 5 fails and the printer
The high-frequency oscillator 3 oscillates even when the insulation of the substrate has deteriorated.
And safety can be improved.

This safety pattern extends to one end of the resistance 17 of the door detection circuit. This is because the resistance value of R17 is sufficiently large compared to the coil resistance of the relay 4.
This configuration is adopted because the relay 4 does not turn on even if the pattern after the resistor R17 is deteriorated in insulation and short-circuited with the relay power supply pattern.

FIG. 2 shows a safety circuit of another microwave oven according to the present invention. The power supply to the relay 4 that drives the high-frequency oscillator is connected to one end of the connector 12 via the relay power supply pattern 14, from one end to the door switch 6 of the main circuit, and from one side of the door switch 6 to control. Through one side of the connector 12 on the circuit, the door signal pattern 15 connects to the relay 4 and the door detection circuit. A first diode 18 and a second diode 19 are inserted from the middle of the door signal pattern 15 to the relay 4 and the door detection circuit, respectively, and the first diode 18 and the second diode 19 are connected from the connector 12 to the first diode 18 and the second diode 19. A safety pattern 16 is provided around the door signal pattern 15 that extends. In this case, the potential of the safety pattern 16 is the potential of the door detection circuit when the door is opened, that is, the chassis ground (OV).

FIG. 3 shows a safety circuit of another microwave oven according to the present invention. The power supply to the relay 4 that drives the high-frequency oscillator is connected to one end of the connector 12 via the relay power supply pattern 14, from one end to the door switch 6 of the main circuit, and from one side of the door switch 6 to control. Door signal pattern 1 via one side of connector 12 on the circuit
5 is connected to the relay 4 and the door detection circuit 13. A chassis ground is externally connected to a pin of the connector 12 between the pin to which the relay power supply pattern is connected and the pin to which the door signal pattern is connected, and is connected to the safety pattern 16 on the printed circuit board. In this case, the potential of the chassis ground is the potential when the door is opened and is OV.

[0022]

As described above, according to the microwave oven of the first aspect, a relay for driving a high-frequency oscillator from a connector on a printed circuit board connected from a door switch and a door signal pattern reaching a door detection circuit. By providing a safety pattern with the same potential as when the door is opened, even if insulation degradation occurs at the door signal pattern, the potential of the door signal pattern will always be the potential of the state where the door is open, and if the latch switch breaks down However, since the radio wave is not emitted when the door is opened, a highly safe microwave oven can be supplied.

In the safety circuit of a microwave oven according to the present invention, a diode is provided in the middle of a door signal pattern from the connector to a relay for driving a high-frequency oscillator and a door detection circuit. In this case, either the relay or the door detection circuit can operate normally even if the alarm occurs, and no radio wave is emitted when the door is open. Therefore, the range from the connector to the diode is the area that needs attention,
It can be easily realized in design.

According to a third aspect of the present invention, there is provided a safety circuit for a microwave oven, wherein a safety pattern having the same potential as when a door is opened is provided around a door signal pattern from the connector to a relay for driving a high-frequency oscillator and a door detection circuit. In this case, it can be easily realized in design by supplying from adjacent pins of the connector.

[Brief description of the drawings]

FIG. 1 is a safety circuit diagram of a microwave oven according to one embodiment of the present invention.

FIG. 2 is a safety circuit diagram of a microwave oven according to another embodiment of the present invention.

FIG. 3 is a safety circuit diagram of a microwave oven according to another embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional microwave oven.

FIG. 5 is a pattern diagram of a printed circuit board of a conventional microwave oven.

[Explanation of symbols]

 2 Control Circuit 3 High Frequency Oscillator 4 Relay 5 Latch Switch 6 Door Switch 12 Connector 13 Door Detection Circuit 14 Relay Power Pattern 15 Door Signal Pattern 16 Safety Pattern 18 First Diode 19 Second Diode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05B 6/68 330 H05B 6/64

Claims (3)

(57) [Claims] 1. A heating chamber for storing food, a high-frequency oscillator coupled to the heating chamber, a door for taking food in and out,
A latch switch and a door switch which operate in conjunction with the door, a connector electrically connected to the door switch and provided on a printed circuit board, a relay for driving the high-frequency oscillator connected to the connector, and the door A control circuit comprising a door detection circuit for detecting a state of the switch, the control circuit comprising a control circuit for controlling the state of the door when the door is opened around a door signal pattern on a printed circuit board from the connector to the relay and the door detection circuit. A microwave oven safety circuit that has a safety pattern with the same potential as the door detection potential. 2. A heating chamber for storing food, a high-frequency oscillator coupled to the heating chamber, and a door for taking food in and out.
A latch switch and a door switch which operate in conjunction with the door, a connector electrically connected to the door switch and provided on a printed circuit board, a relay for driving the high-frequency oscillator connected to the connector, and the door A control circuit comprising a door detection circuit for detecting a state of a switch, the control circuit comprising a first diode on the way from the connector to the relay, and a first diode on the way from the connector to the door detection circuit. A second diode is provided, and a safety pattern having the same potential as a door detection potential when the door is opened is provided around a pattern on a printed circuit board from the connector to the first diode and the second diode. Microwave oven safety circuit configured. 3. A heating chamber for storing food, a high-frequency oscillator for heating food connected to the heating chamber, a door for taking food in and out, a latch switch and a door switch operating in conjunction with the door, A control circuit including a connector electrically connected to the door switch and provided on a printed circuit board; a relay connected to the connector for driving the high-frequency oscillator; and a door detection circuit for detecting a state of the door switch. The control circuit has a safety pattern having the same potential as a door detection potential when the door is opened around a door signal pattern on a printed circuit board from the connector to the relay and the door detection circuit. The pattern is set between the pin to which the relay power pattern of the connector is connected and the pin to which the door signal pattern is connected. Configuration and the safety circuit of the microwave oven to be connected to the pin with chassis ground was.