KR860001415Y1 - Unnormal temperature detecting circuit for a electronic ranger - Google Patents

Abstract

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Description

Microwave Odd Condition Control Circuit

Circuit diagram of the present invention.

* Explanation of symbols for main parts of the drawings

MIC: Micom A: Temperature sensing circuit

B: Comparison part for thermistor opening detection

C: Comparison section for thermistor short circuit detection

D: Output control circuit D ₁ , D ₂ : Diode

R ₁ , R ₂ : Resistance TH: Thermistor

P: Abnormal detection terminal 3,4: Comparator

1: amplifier 2: temperature comparator

The present invention relates to an abnormal state control circuit of a microwave oven that detects an abnormality of the thermistor whose resistance is changed according to the temperature of the microwave oven in the microcomputer microwave oven.

The microwave oven heats food at high frequency, so it is always designed to pay attention to safety issues, and it is designed to heat food to the set temperature according to the temperature of the thermistor by the probe. The resistance value changes accordingly by converting the analog state signal of the thermistor into a digital signal and applying it to the microcomputer to control the output state of the high frequency in accordance with the temperature, and the magnetron is driven when the thermistor is open for cooking. The comparator for detecting the thermistor open is configured to block the circuit breaker, but since there is no circuit for detecting the short circuit of the thermistor, when installing the probe to detect the cooking temperature of the drink during cooking Attention was always to be put in the food. In other words, the probe has a built-in temperature detector thermistor is configured to detect the exact temperature of food, rarely open the thermistor, except in the case of failure or disconnection of the device, When cooking food, the probe could be incorrectly inserted in the food, causing the microwave and thermistor to short-circuit.

In view of the above, the present invention allows the microcomputer to shut off the output state at the time of short-circuit and opening of the thermistor to stop driving in an abnormal state. The output of the amplifier according to the resistance of the thermistor is always The open sensing comparator and the thermistor short sensing comparator are configured to be applied from the diode to the microcomputer to increase the safety of the microwave oven in an abnormal state.

This will be described below with reference to the accompanying drawings.

The temperature sensing unit (A) of the present invention has a temperature comparator through a resistor (R ₃ ) in the amplifier (1) by distributing the thermistor (TH) and the resistor (R ₂ ) with the resistor (R ₁ ) as in a conventional microwave oven. The output of the temperature comparator 2 configured to be applied to (2) and compared with the reference voltage divided by the drop (R ₄ ) (R ₅ ) to the microcomputer (MIC) through the analog / digital converter (5). It is configured to be authorized.

In the normal temperature sensing circuit (a), the output of the amplifier (1) is transferred from the diode (D ₁ ) (D ₂ ) through the comparison circuit (b) for thermistor open detection and the comparison section (b) for thermistor short-circuit detection. that is configured to be applied to the abnormality detection terminal (P) of (MIC), deoeo Mr openness resin comparison unit (B) is a resistance (R ₆₎ (R ₇₎ reference voltage terminals between (-) and the voltage applied to the terminal (+) After comparing the voltages at the comparator 3 and distributing them to the resistors R ₈ (R ₉ ), the comparator for detecting the short circuit (C) between the resistors R ₁₀ (R ₁₁ ) is provided. The voltage is compared between the reference voltage terminal (+) and the applied voltage terminal (-) by the comparator 4, and then distributed to the resistors R ₁₂ and R ₁₃ to be outputted. When TH) is normally driven, the output voltage of the comparators 3 and 4 is set to a low potential state.

Here, the voltage applied to the terminal (+) of the comparator 3 at the time of opening the thermistor TH is higher than the reference voltage divided by the resistors R ₆ and R ₇ so as to sense the voltage of the thermistor TH. In the case of a short circuit, the voltage applied to the terminal (-) of the comparator 3 is lower than the reference voltage divided by the resistors R ₁₀ (R ₁₁ ) so that the resistor R ₆ (R) can be detected. ₇ ), (R ₁₀ ) (R ₁₁ ) to distribute power (Vcc).

In the figure, reference numeral (d) denotes an output control circuit driven by a microcomputer (MIC).

In the present invention configured as described above, in the normal driving state of the microwave oven, the power Vcc distributed by the resistance value of the thermistor TH and the resistor R ₁ and R ₂ is applied according to the temperature of the amplifier ( After amplifying at 1), compare the status signal applied to the temperature comparator 2 and the voltage set by the resistor R ₄ (R ₅ ) in the temperature comparator 2 to compare the analog status signal in the analog / digital converter 5. The digital signal is converted into a digital signal and applied to the microcomputer MIC to control the output control circuit d according to the temperature change of the thermistor TH.

As such, when the thermistor TH is driven normally, the comparator 3 of the thermistor open detection comparator 3 is set to have a voltage higher than that of the amplifier 1 at the reference voltage terminal (-). In the comparator (4) of the comparator (c) for the short circuit detection of the tether thermistor, the voltage applied from the reference voltage terminal (+) is set lower than the output voltage of the amplifier (1). The output is low-potential signal is output, but the diode (D ₁ ) (D ₂ ) is cut off so that the high-potential state is not applied to the abnormal detection terminal (P) of the microcomputer (MIC), the gas range will operate normally. . However, when the thermistor TH is opened and the thermistor TH is opened, the power supply Vcc is applied from the amplifier 1 through the resistor R ₁ , so that the reference voltage terminal (-) of the comparator 3 is applied. Due to the higher voltage of the amplifier (1), the output signal of the high potential state of the comparator (3) via the resistor (R ₈ ) (R ₉ ) the abnormality detection terminal (P) of the microcomputer (MIC) at the diode (D ₁ ) Since the state signal is applied to the microcomputer MIC, the power applied to the output control circuit D is cut off, thereby preventing the microwave oven from being driven when the demister is opened.

At this time, a voltage higher than the reference voltage terminal (+) is also applied to the terminal (-) of the comparator 4 to the comparator 4 of the comparator (C) for detecting the short circuit. Blocked by D2).

Then, when the thermistor TH of the temperature sensing unit is shorted, the power supply Vcc flows from the resistors R ₁ and R ₂ to the ground from the amplifier TH to be depressed in the amplifier 1. Since the voltage set at the reference voltage (+) is higher than the voltage applied to the comparator (-) terminal (-) of the comparator (C) for the MR short circuit detection, the comparator (4) has a resistance (R _12). (R ₁₃ ) is applied to the abnormality detection terminal (P) of the microcomputer (MIC) through the diode (D ₂ ), so that the microwave oven can be prevented from being driven during the short circuit of the thermistor as described above. The low phase signal output from the comparator 3 is blocked by the diode (D ₁ ).

As described above, the present invention sets the reference voltage of each comparator (3) and (4) in the comparator (b) for thermistor open detection and the comparator (c) for the short circuit detection in the event of an abnormality of the thermistor (TH). The voltage and the voltage applied from the amplifier 1 are compared and applied to the microcomputer so that the power supply of the output control circuit D can be cut off at the microcomputer. In this case, a display unit such as a light emitting diode is installed in the output control circuit D. It is possible to identify the abnormality of the microwave oven by the display unit, and to detect the short-circuit of the thermistor at all times and to know whether the probe is correctly inserted in the food during cooking. It is.

Claims (1)

In a microwave oven, in which a normal temperature detecting unit (A) is connected to a microcomputer (MIC) and configured with a thermistor open detecting comparator (B) for detecting the open state of the thermistor (TH), B) The comparator for detecting the short circuit (c) is configured in parallel in parallel with the reference voltage of the comparator 4 which is distributed and applied to the resistors R ₁₀ and R ₁₁ rather than the output of the amplifier 1 when the thermistor is opened. The abnormal state control circuit of the microwave oven configured to be set lower and connected to the abnormality detection terminal P of the MIC via the reverse blocking diodes D ₁ and D ₂ .