KR950002898Y1 - The door of a microwave range - Google Patents

Abstract

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Description

Microwave Door Safety

1 is a circuit diagram showing the overall configuration of the door safety device of the present invention.

2 is a perspective view showing a microwave oven to which the door safety device of the present invention is applied.

3 is a circuit diagram showing a conventional door safety device.

* Explanation of symbols for main parts of the drawings

1: microcomputer 3: magnetron

4 door detection unit 8 heating chamber

8A: Door contact surface 10: Door

AC: AC Power T2: High Voltage Transformer

CdS: Light Sensor

The present invention relates to a door safety device for a microwave oven, and more particularly, to a door safety device for a microwave oven that detects whether a door is opened or closed by an optical sensor to compensate for a malfunction of a door switch due to mechanical wear or a defect.

As shown in FIG. 3, a driving circuit of a conventional microwave oven is typically a microcomputer 31, a power supply transformer T1, a temperature fuse 32, a switch SW1, SW2, an oven lamp L1, and a fan. Motor (FM), relay (RL1), sensing switch (SW3), triac (Q1), high voltage transformer (T2), high voltage diode (D1), high voltage capacitor (C1) and magnetron (33) The operation relationship thereof is as follows.

First, when AC power is applied to the power plug 34, the microcomputer 31 connected to the secondary side of the power transformer T1 starts to operate. In this case, when the door of the microwave oven is omitted, As the switch SW1 and the sensing switch SW3 are turned on by the latch of the door, and the switch SW2 is turned off, the microcomputer 31 can detect that the door is closed by the sensing switch SW3. .

In this state, when the cooking command is inputted through the key input unit, an AC voltage and a high voltage are generated on the secondary side of the high voltage transformer (T2), and the high voltage is again supplied through the high voltage capacitor (C1) and the high voltage diode (D1). Since it is rectified and applied to the magnetron 33, the magnetron 33 is driven to emit microwaves, which are electromagnetic waves.

In addition, since the oven lamp (L1) is in the lighting state can be heated inside the heating chamber, and at the same time the fan motor (FM) can be driven to cool the magnet tone 33, wherein the temperature of the magnetron 33 When more than a predetermined value (about 130 ℃) the temperature fuse 32 is switched from the on state to the off state because of this the power is cut off, the driving of the magnetron 33 is cut off.

However, in the conventional device, when the door is opened while the magnetron 33 is in operation, the switches SW1 and SW2 and the detection switch SW3 are opened and closed by the mechanical operation of the door latch, so that the latch of the door may be broken. When an abnormality occurs at the contacts of the switches, the microwave oven malfunctions, and there is a risk of leakage of electromagnetic waves, as well as a problem in that the reliability and stability of the product are deteriorated.

The present invention has been devised to solve such a conventional problem. The door detection unit is added to detect the opening and closing of the door by using an optical sensor in the circuit configuration of the existing microwave oven, and the opening and closing of the door by the output signal of the door detection unit. By judging whether or not to control the voltage applied to the magnetron, it is possible to precisely control the circuit in the event of mechanical wear or malfunction of the switch, thereby providing a door safety device of the microwave oven that can further improve the reliability and stability of the product. The purpose of the present invention will be described in detail with reference to the accompanying drawings of FIGS. 1 and 2.

As shown in FIG. 1, the inventive device includes a microcomputer (1), a power transformer (T1), a thermal fuse (2), a switch (SW1, SW2), an oven lamp (L1), a fan motor (FM), In a driving circuit of a microwave oven provided with a relay (RL1), a sensing switch (SW3), a triac (Q1), a high voltage transformer (T2), a high voltage diode (D1), a high voltage capacitor (C1), and a magnetron (3). The input terminal P of the microcomputer 1 includes a variable resistor VR1, resistors R1 to R3, and transistors Q2 and Q3, and outputs an optical sensor CdS whose resistance value is converted according to the amount of light. The door detection unit 4 for detecting whether the door is opened or closed by a signal is characterized in that the connection.

2 is a perspective view of a microwave oven showing an embodiment to which the present invention is applied, wherein reference numeral 5 denotes a microwave oven body, 6 a key input unit, 7 a tray, 8 a heating chamber, and 8A a door in front of the heating chamber. A contact surface, 9 is a door latch, 10 is a door, 11 is a light shielding film which prevents light from entering the light sensor CdS installed on the door contact surface 8A when the door 10 is closed, and 12 is a door latch 9 Is inserted into the hole for operating the switches SW to SW3.

Referring to the operation and effect of the device of the present invention configured as described above are as follows.

First, when the door 10 is closed, since light from the outside is not input to the optical sensor CdS, its resistance value is increased, so that the natural pressure induced between both ends of the variable resistor VR1 of the door detection unit 4 is increased. Will decrease.

Therefore, since the base bias voltage of the transistor Q2 decreases below the so-called voltage 0.7V, the transistor Q2 is turned off and the transistor Q3 is also turned off.

Accordingly, since the 'high' signal from the power terminal B + is applied to the input terminal P of the microcomputer 1 through the resistor R3, the microcomputer 1 receives the 'high' signal and the door is closed. By recognizing and turning on the relay RL1, a closed circuit is formed, and the magnetron 3 is driven to cook food on the tray 7.

On the other hand, when the door 10 is opened, the external light is incident on the optical sensor CdS, and the resistance thereof decreases, so that the voltage induced by the variable resistor VR1 is higher than the predetermined voltage (0.7V). The transistor Q2 is turned on.

Therefore, since the transistor Q3 is also turned on, a 'low' signal is applied to the input terminal P of the microcomputer 1 to detect that the door 10 is opened. Accordingly, the microcomputer 1 relays the relay RL1. By turning off), the power supply to the magnetron 3 is cut off, the operation of the magnetron 3 is stopped, and leakage of electrons can be prevented.

On the other hand, the driving of the switches SW1, SW2, the sensing switch SW3, the fan motor FM, and the like are made by the same method as the conventional case, and thus the operation relation thereof is omitted, and only the switches SW1, SW2 are Even when an abnormality occurs in the contact point of the contact point and the sensing switch SW3, it is determined whether the magnetron 3 is driven by the operation state of the door detecting unit 4, which is the device of the present invention.

As described above, the device of the present invention detects whether the door is opened or closed by using an optical sensor, so that the operation speed is significantly faster and more accurate than the safety device due to mechanical operation, thereby improving the reliability of the product. In particular, it is possible to prevent malfunction of the switch due to mechanical wear or coupling, so that the microwave oven can be used more safely.

Claims (2)

The microcomputer 1 for controlling the heating cooking operation of food, the high voltage transformer T2 to generate a high pressure by applying an AC power source AC under the control of the microcomputer 1, and the high voltage transformer T2 is generated. Magnetron (3) for heating and cooking food by generating electromagnetic waves at high pressure, and the light sensor (CdS) that the light is incident and blocked by the opening and closing of the door 10, and according to the output signal of the light sensor (CdS) The microcomputer 1 includes a door detection unit 4 for inputting an open / close detection signal of the door 10 to the microcomputer 1, and the microcomputer 1 opens or closes the door 10 by the detection signal of the door detection unit 4. The door safety device of the microwave oven, characterized in that the AC power (AC) is not applied to the high voltage transformer (T2) at the time of opening the door (10). The door 10 according to claim 1, wherein the optical sensor CdS is fixed to the door contact surface 8A on the front surface of the heating chamber 8, and the door 10 is positioned at a predetermined position of the door 10 opposite to the fixed position of the optical sensor CdS. The door safety device of the microwave oven, characterized in that for attaching a light shielding film (11) to prevent light from entering the light sensor (CdS) when closing.