KR0121991B1 - Humidity sensor of microwave oven - Google Patents

Abstract

The method of checking an abnormal state of a humidity sensor of a microwave oven in which the humidity is sensed after the equilibrium of the humidity sensor is adjusted under the control of a microcomputer during an automatic cooking, comprises the steps of: if two specific keys set as an abnormal state checking key are inputted, performing a pre-setting function for the equilibrium adjustment of the humidity sensor without heating; and comparing the output value of the humidity sensor based on the pre-setting with a predetermined range value for determining a normal state of the humidity sensor, to thereby display the normal/abnormal states of the humidity sensor.

Description

How to check bad humidity sensor of microwave

1 is a humidity detection circuit diagram of a general microwave oven.

2 is a flow chart of the humidity sensor bad check control of the microwave oven according to the present invention.

* Explanation of symbols for main parts of the drawings

1: humidity sensor unit 2: humidity detection unit

3: microcomputer 4: parallel control unit

TH1, TH2: Thermistor (Humidity Sensor) OPI: Operational Amplifier

R1-R11: Resistance ZDI: Zener Diode

The present invention relates to a method for checking a defective humidity sensor of a microwave oven, and in particular, a humidity sensor defective check of a microwave oven, which allows simple checking of a defect by performing presetting of a humidity sensor without heating by simultaneously pressing two specific keys. It is about a method.

In general, in the sensor type microwave oven, for automatic cooking, the time when the amount of humidity is rapidly increased is detected as a boiling point, and the additional time is calculated by multiplying the addition coefficient according to the cooking name from the time of heating to the detection of the boiling point. The heating is continued for the additional time to complete cooking.

Therefore, it is possible to obtain the desired cooking state by setting the cooking time correctly only when the humidity amount is accurately detected.

FIG. 1 is a schematic diagram of a humidity sensing circuit of a general microwave oven. As shown in FIG. 1, two thermostats TH1 and TH2 and two resistors R2 and R3 connected in series are connected to a power supply terminal (+ 12V). The humidity sensor unit 1 for outputting the humidity detection voltage through each series connection point (a) and (b) by connecting in parallel between the connected resistor R1 and the ground terminal in series, and the humidity sensor unit 1 in series The output voltages of the connection points (a) and (b) are differentially amplified through the resistors R4 and R5 and the operational amplifier OP1, and the input terminals of the microcomputer 3 through the resistors R6 and the zener diode ZD1 ( A plurality of resistors R7-R11 are applied to the bridge resistors R2 and R3 of the humidity sensor unit 1 by the humidity detection unit 2 to be applied to the A / D and the balance control signal of the microcomputer 3. It consists of an equilibrium control unit (4) for selectively connecting the troops to adjust the bridge balance.

The operation and problems of the humidity sensing circuit of the general microwave oven configured as described above are as follows.

When the power is applied, the voltage at each series connection point (a) (b) of the two thermistors TH1 (TH2) and resistors R2 (R3) is differentially amplified by the humidity detector 2 to It is entered at the input terminal.

At this time, the microcomputer 3 controls the balance control unit 4 so that the potentials of the two equilibrium points a and b of the humidity sensor unit 1 are equal to each other based on the input value of the input terminal A / D. By adjusting the parallel resistance value, the equilibrium is achieved.

Subsequently, when cooking is started by heating, the resistance values of the thermistors TH1 and TH2 vary according to the amount of humidity, and thus the unbalanced voltages of the two equilibrium points a and b cause the humidity detection unit 2 to operate. It is differentially amplified through and input to the microcomputer 3.

In this way, the microcomputer 3 detects the amount of humidity to control automatic cooking.

However, since the humidity detection circuit of the conventional microwave oven has been programmed to detect the humidity value only when the microcomputer 3 starts automatic cooking in order to detect the humidity, in order to determine whether the humidity sensor and its surrounding circuits are defective, During cooking, the humidity sensor was checked for defects only using an oscilloscope.

However, the use of the check equipment such as an oscilloscope may be possible in the production line, but it is not possible to determine whether the humidity sensor is defective because the check equipment is not readily available at the place where the microwave oven is installed, that is, at home.

In addition, since the output of the humidity sensor should be determined by using a check device such as an oscilloscope while cooking in the production line, the check takes a long time (about 30 seconds or more) and has a disadvantage.

It is an object of the present invention to improve the conventional problem by pressing two specific keys at the same time to provide a humidity sensor failure detection method of the microwave oven to check and display whether the humidity sensor and its peripheral circuit failure within a short time. It is to.

The object of the present invention is to set the two specific keys on the keyboard at the same time to set the humidity sensor automatic check, and when the two specific keys are input at the same time, and performs a preset function for the humidity sensor balance control without heating By comparing the output value of the humidity sensor after the preset with the preset normal determination range, it is achieved by displaying on the display unit whether it is normal or defective.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the humidity sensor failure detection method of the microwave oven according to the present invention, the existing humidity detection circuit as shown in FIG. 1 is applied as it is, and when two preset predetermined keys are simultaneously inputted, the microcomputer 3 performs The preset function is performed like the control flow of 2 degrees to determine whether the humidity sensor and its surrounding circuit are normal or defective.

First, when two specific keys of the operation keys of the microwave oven are pressed at the same time, the preset mode for automatically checking the humidity sensor as shown in FIG. 2 is set.

Accordingly, when two preset keys are pressed simultaneously, the microcomputer recognizes the humidity sensor automatic check mode and presets the humidity sensing circuit.

Here, the preset of the humidity sensing circuit changes the balance control data outputted by the microcomputer 3 to the balance control port in order, so that the balance control resistors R7-R11 are connected to the resistors R3 connected to the bridge resistor R2. The parallel connection is selected. In this way, while changing the balance adjustment resistance value in order to store the detected value input to the analog / digital input port (A / D) in each case, the value corresponding to the most equilibrium value among the stored values, that is, the humidity sensor unit (1 The equilibrium adjustment data when the potentials of the a and b points of) are the same are set in the equilibrium adjustment ports (P1-P5) to perform the preset.

In this way, the humidity sensing circuit is preset without heating, and the resulting detected value is compared with a preset normal determination reference range.

If the result of the comparison is outside the normal determination standard range, it is determined as an error and an error indication is displayed.

Here, when the two specific keys are input at the same time, by ringing the bell indicating that the automatic humidity sensor check operation, it can be seen that the check is performed. In addition, even after the end to distinguish between a normal state and a bad state, such as ring tone or buzzer sound to inform.

As described in detail above, according to the present invention, by performing the preset function of the humidity sensor without heating, it is possible to check the defect or disconnection of the humidity sensor and its peripheral circuit in a simple and fast time (about 8 seconds). There is.

Claims (3)

In a microwave oven in which a microcomputer adjusts the equilibrium of the humidity sensing circuit during automatic cooking and senses humidity, and controls cooking, set the humidity sensor automatic check that two specific keys on the keyboard are simultaneously input. When two are input at the same time, it performs preset function for balancing the humidity sensor without heating and compares the output value of the humidity sensor based on the preset with the preset normal determination range. Defect check of humidity sensor of microwave oven. According to claim 1, At the start of the humidity sensor failure check by ringing a predetermined ring to indicate that the humidity sensor failure check, the visual display of the humidity sensor failure check result through the display for a certain time and hearing by a bell or buzzer sound Humidity sensor failure detection method of a microwave oven, characterized in that made to display the normal. 2. The method of claim 1, wherein a dedicated humidity sensor operation check key is provided to automatically check the humidity sensor.