CN2836397Y

CN2836397Y - Over-voltage protection circuit for microwave oven control board

Info

Publication number: CN2836397Y
Application number: CN 200520123045
Authority: CN
Inventors: 申昕
Original assignee: LG Electronics Tianjin Appliances Co Ltd
Current assignee: LG Electronics Tianjin Appliances Co Ltd
Priority date: 2005-11-14
Filing date: 2005-11-14
Publication date: 2006-11-08
Anticipated expiration: 2015-11-14

Abstract

The utility model relates to an over-voltage protection circuit for microwave oven control boards. A recoverable thyristor TR is connected in series with a rectification voltage stabilizing circuit which is composed of diodes D01, D02, capacitors C01, C02, C05, transistors Q01, Q02 and a voltage stabilizing diode ZD. The positive electrode of the thyristor TR is connected with the negative electrode of the diode D01 and one electrode of the capacitor C01, the negative electrode of the thyristor TR is connected with the positive electrode of the medium capacitor C02 and the control electrode of the thyristor TR is directly connected with the control port Vp of a chip. When the working voltage of the microwave oven chip is too high, the control port of the chip can output a pulse signal into the control electrode of the thyristor to switch off the thyristor, and a microwave oven can stop working to protect the chip from working at high voltage and the transistors Q01, Q02 from being damaged. When normal voltage is input, the microwave oven continues to work again. As a result, the utility model realizes the over-voltage protection of microwave oven control boards and ensures that microwave ovens can be free from damage under the condition that input voltage increases suddenly.

Description

The microwave oven control panel excess voltage protection

Technical field

The utility model relates to microwave oven, particularly relates to the control circuit of microwave oven.

Background technology

Microwave oven is the household electrical appliance cooker that utilizes high-frequency microwave that food is heated, and the frictional heat that produces by food molecule high vibration under the radiation effects of high-frequency microwave heats and cooking food.During the cooking in microwave oven operation, microwave penetration food, can inside and outside heating simultaneously, it is fast and use plurality of advantages easily to have an efficient height, speed.Therefore, microwave oven progressively becomes widely used domestic electric appliance.

The outward appearance of microwave oven is rectangular shape, and there is fire door in the housing front of cuboid, fire door one side setting operation key.Form furnace chamber in the housing, the top and side of furnace chamber is provided with the internal structure of microwave oven, mainly contains magnetron, waveguide, control circuit device and blender etc.

Magnetron is the heart of microwave oven, is a kind of vacuum device, is used to produce the continuous microwave of heat food.The microwave that magnetron produces is carried and is radiated on the food in the furnace chamber by the waveguide of high-conductive metal material.Blender is made with the metal such as the magnadure plate that conduct electricity very well, intensity is high, just as screw, drive by small machine, in rotatablely moving, constantly change reflection angle to microwave radiation, thereby improve the distribution of microwave field in the furnace chamber, the food in the furnace chamber is heated evenly.The microwave oven that has is not provided with blender, and the rotating disk of support food is set in furnace chamber bottom, and the food that rotatablely moves with rotating disk also can be subjected to the even heating of microwave radiation.

Fire door is the passage of placing food and take out food in the furnace chamber in furnace chamber, has enough mechanical strengths, and that long-term switch uses is still indeformable, non-cracking and microwave leakage do not occur.The observation window of fiberglass is equipped with in fire door central authorities, accompanies intensive pore metallic shield net in the fiberglass, can see cooking status in the stove during use, can make the unlikely leakage of microwave again.

Control circuit device is arranged in the housing; comprise control circuit and respective electric parts thereof; mainly contain power controller, high-tension transformer, high-voltage capacitor, overheat protector, timer, interlocking switch and interlocking pilot switch, rotary tray motor (or agitator motor), fan electromotor etc., its function guarantee and control the normal operation of whole microwave oven.

Computer control type microwave oven has diversified controlled function, can finish multiple work according to previously selected program.Computer control type microwave oven is realized controlled function by chip, and its controlled function mainly contains: the cooking is regularly selected, cooking power selection, and microwave oven regularly starts, temperature control, two kinds of cooking operation program compatibilities, and audible alarm etc.

Fig. 1 is general microwave oven structure schematic diagram.During the applied microwave stove, open the fire door 6 in micro-wave oven casing 1 front, food is put in the furnace chamber 8, close upper furnace door 6, push key 9, control circuit board conducting, each electric component and chip operation, the microwave that magnetron 2 produces award the food homogeneous radiation heating in the furnace chamber 8.After finishing cooking heating according to the predefined time, open fire door 6 again and take out foods.

Fig. 2 is a kind of microwave oven control panel power unit circuit diagram of prior art.As shown in the figure, control board power unit circuit is connected with low-tension transformer, the regulator rectifier circuit that comprises diode D01 and D02, capacitor C01 and C02 and C05, transistor Q01 and Q02 and voltage stabilizing didoe ZD formation for chip provides operating voltage, makes it finish various controlled function.

But the circuit of the microwave oven control panel power unit of above-mentioned prior art can not be realized protection under the overvoltage situation.Because the fluctuation of electrical network, perhaps the microwave oven use is incorrect, and too high voltages can appear in circuit, and transistor Q01 and Q02 are damaged; And chip operating voltage is too high, also can cause chip operation undesired, influences the normal computer control of microwave oven.

Summary of the invention

The utility model is can not realize protection and proposition at the circuit of the microwave oven control panel power unit of prior art under the overvoltage situation; its objective is recoverable thyristor of series connection on primary circuit; when the too high situation of chip operating voltage occurs; thyristor turn-offs; microwave oven quits work; the protection chip is not worked under high voltage, avoids the damage of transistor Q01 and Q02.

Recoverable thyristor of series connection on the related microwave oven control panel excess voltage protection of the utility model; the anode of thyristor is accepted the direction of drawing of low-tension transformer; the negative electrode of thyristor leads to the chip port direction, and the control of thyristor extremely directly connects the chip control port.

When the related microwave oven of the utility model is worked, if too high chip operating voltage occurs, the chip controls port can be exported a pulse signal and enter the thyristor control utmost point, thyristor is turn-offed, alarm sends buzzing alarming sound, microwave oven quits work, and the protection chip is not worked under high voltage, avoids the damage of transistor Q01 and Q02; When input voltage just often, microwave oven works on again.Therefore, the utility model has been realized the overvoltage protection of microwave oven control panel, ensures that microwave oven increases under the situation at the burst input voltage not to be damaged.

Description of drawings

Fig. 1 is general microwave oven structure schematic diagram.

Fig. 2 is the microwave oven control panel power unit circuit diagram of prior art.

Fig. 3 is a microwave oven control panel power unit circuit diagram of the present utility model.

Main mark explanation among the figure:

1, housing 2, magnetron

3, waveguide 4, blender

5, reflecting plate 6, fire door

7, observation window 8, furnace chamber

9, operation keys A, alarm circuit

ZD, voltage stabilizing didoe PT, transformer

UO, chip Vs, chip connectivity port

TR, thyristor Vp, chip controls port

Embodiment

Now in conjunction with the accompanying drawings to being described further for the utility model.As Fig. 3 and shown in Figure 2, the related microwave oven control panel excess voltage protection of the utility model is that recoverable thyristor TR of series connection constitutes on the circuit of the microwave oven control panel power unit of prior art.The anode of thyristor TR is accepted the direction of drawing of low-tension transformer PT, and is connected with the negative pole of diode D01 and the electrode of capacitor C01; The negative electrode of thyristor TR leads to the port direction of chip UO, with dielectric capacitor C02 positive pole be connected; The control of thyristor TR extremely directly connects chip control port Vp.

Claims

1, a kind of microwave oven control panel excess voltage protection; comprise diode D01 and D02, capacitor C01 and C02 and C05, transistor Q01 and Q02 and voltage stabilizing didoe ZD; it is characterized in that; recoverable thyristor TR of series connection on the circuit; the anode of thyristor TR is accepted the direction of drawing of low-tension transformer PT, and the negative electrode of thyristor TR leads to the port direction of chip UO.

2, microwave oven control panel excess voltage protection according to claim 1; it is characterized in that; the anode of thyristor TR is connected with the negative pole of diode D01 and the electrode of capacitor C01; the negative electrode of thyristor TR is connected with the positive pole of dielectric capacitor C02, and the control of thyristor TR extremely directly connects chip control port Vp.