KR850002655Y1 - Error rejecting circuit - Google Patents

Abstract

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Description

Microwave malfunction prevention circuit

1 is a block diagram of the main part of the microwave oven.

2 is a circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

1: rectifier 2: switching circuit

3: relay signal detection circuit 4: relay coil

5: key control unit 6: microprocessor

8: Malfunction prevention circuit A: Square wave output port

B: Relay output port 7: Display part

The present invention relates to an electronic circuit for preventing a malfunction in a microprocessor controlling the operation of a microwave oven and causing a relay for switching the magnetron to malfunction.

Conventional microwave ovens have a built-in microprocessor that controls the operation of each part in response to various cooking instructions. Most of these microprocessors operate normally, but sometimes they operate abnormally due to lightning, powerful electrical sparks, and irregular interruptions of input AC power. There is a case to enter. If this abnormal operation occurs at the output port connected to the magnetron driving relay, powerful microwaves may be sent out irrespective of the user's intention to damage the food or the product, and in severe cases may cause a fire.

The present invention eliminates the above-mentioned risks, and installs a relay malfunction prevention circuit in a part of the output port of the microprocessor to check the operation of the magnetron driving relay by checking whether the program execution is normal or abnormal. The purpose of the present invention is to improve the stability and reliability of the microwave oven by such a series of operations.

Hereinafter, the configuration, operation, and effects of the present invention will be described in detail.

The present invention is a blocking capacitor (C1) connected to the square wave output port (A) to block the DC component, the diode (D1) and the rectifier (1), rectifier (1) connected between the output terminal of the capacitor (C1) and the ground (1) A switching circuit 2 connected to the output side, and a relay coil 4 connected between the switching circuit 2 and the relay signal detection circuit 3 are sequentially coupled.

Reference numeral B denotes a relay output port, 5 a key operation unit, 6 a microprocessor, 7 a display unit, and 8 a malfunction prevention circuit.

1 is a block diagram of a microwave oven using the present invention, in which there is no malfunction prevention circuit 8 and only a relay signal detection circuit 3 is provided in the existing microwave oven. The specific circuit is shown in FIG. 2 of the multi-arlington connection transistors Q4 and Q5. When the microprocessor 6 commands the cooking signal in response to the input of the key operating section 5, the relay output port B ), A high level signal is sent out. In response to this signal, the relay signal detection circuit 3 operates so that the relay coil 4 operates.

Since the magnetron drive transformer is connected to the contact of the relay coil 4, the microwave is sent out when the contact is in the "on" state.

If the microprocessor 6 does not command the cooking signal and lightning, electric sparks, impulse noise, abnormal power supply fluctuations are affected, the relay output port B to be kept at a low level is "high". "Can change into a state. At this time, the microwave is transmitted irrelevant to the user's will, which is very dangerous.

The present invention is intended to exclude such a risk, the specific circuit diagram is the same as FIG.

If everything is in a normal state, a square wave is output from the output port of the microprocessor 6 (A: part of the unused output port or the output port being used can be used as it is).

When the square wave is output from the output port A and applied to the blocking capacitor C1, the direct current is blocked and the pure AC signal square wave is applied to the anode of the diode D2. Therefore, the square wave applied to the rectifier 1 is applied to the transistor Q1 of the switching circuit 2 after the half wave average value is converted into direct current. When the average voltage becomes equal to or more than the forward bias value of the transistor Q1 and the diode D3, the transistor Q1 is turned on through the resistor R1. Accordingly, the B + voltage is applied to the collectors of the transceivers Q2 and Q3 and the relay signal detection circuit 3 is turned on according to the "high" state of the relay output port B (when there is a cooking command). Since the current flows through the transistors Q2 and Q3 → relay coil 4 and transistors Q4 and Q5, the relay RL operates.

If the microprocessor 6 is in an abnormal state due to external influences, the square wave output port A and the relay output port B are both in a "high" state, so this DC component is blocked by the blocking capacitor C1. do.

Therefore, no current flows through the relay RL because the transistors Q1, Q2 and Q3 are not conductive.

Here, the square wave output port A outputs a square wave when the microprocessor 6 is in a normal state regardless of whether cooking is in progress or not, and in abnormality, the square wave output port A is displayed as "high level".

As described above, the present invention monitors whether the microprocessor 6 is in a normal state or whether the program is normally executed, thereby preventing the magnetron driving relay of the microwave oven from malfunctioning.

Therefore, the present invention can reduce the risk of fire due to malfunction of the magnetron, can prevent the loss of energy, and there is an advantage of preventing damage to the cookware or the main body.

In addition, there is an advantage that can improve the reliability of the product from this.

Claims (1)

Blocking capacitor (C1) connected to the square wave output port (A) to cut off the DC portion, connected to the output shaft of the diode (D1), rectifier (1), rectifier (1) connected between the output terminal of the capacitor (C1) and ground The malfunction prevention circuit of the microwave oven comprised from the switching circuit 2, the relay circuit 4, etc. which are connected between the switching circuit 2 and the relay signal detection circuit 3.