KR20000032378A - Prevention device for dropping of pcb in refrigerator - Google Patents

Abstract

PURPOSE: A prevention device for dropping of PCB(Printed Circuit Board) in a refrigerator is provided to prevent misoperation and breakdown of the refrigerator from occurring due to dropping by detecting the dropping in the inside of PCB and removing the detected dropping by driving a heater as much as detected. CONSTITUTION: A prevention device for dropping of PCB in a refrigerator includes a bridge circuit (10) having a first thermistor(R1) sensing the open air humidity of the refrigerator and a second thermistor(R2) sensing the humidity of inside of the refrigerator to maintain the balance, an inverting amplifier(20) outputting a high signal if a voltage output corresponding to the humidity detected in the second thermistor is under a predetermined reference voltage, a microcomputer(70) outputting a predetermined control signal to correspond to the volume of applied voltage if the voltage output from the inverting amplifier is applied, and a heater driving part operating a heater to correspond to the volume of the voltage by operating a relay(90) when the control signal is output from the microcomputer(70).

Description

Dew prevention device of printed circuit board of refrigerator.

The present invention relates to a device for preventing dew condensation of a refrigerator PCB, and in particular, a refrigerator that detects dew condensation inside a refrigerator main PCB cover and drives a heater by a detected amount to prevent malfunction and failure of the refrigerator in advance. The present invention relates to a device for preventing dew formation of a PCB.

Generally, a refrigerator is a household appliance used to freeze and refrigerate food by using a cooling cycle. The refrigerator exchanges refrigerant gas, which has been compressed at high and high pressure in a compressor, to the outside air in a condenser. After liquefied by filtration in the receiver dryer (Receiver dryer), through the capillary tube (Capillary Tube) is adiabatic expansion with low-temperature, low-pressure liquid refrigerant.

In particular, a fan-cooling refrigerator exchanges heat with cavity air in a cabinet circulated by a fan in an evaporator to freeze and refrigerate food stored by evaporative heat of refrigerant absorbed. Temperature control is performed as the drive / stop control of the fan and the compressor.

However, such a refrigerator is indirectly contacted by cold air inside and hot air outside of the door gasket and the cabinet flange of the refrigerating and refrigerating compartment, thereby causing dew formation. .

That is, if the refrigerator continues to operate, for example, when the temperature of the cabinet trimmer is -5 ° C and the external temperature is 30 ° C, dew is formed due to a temperature difference between the two.

This dew condensation will eventually contaminate the refrigerator, degrading its quality and reliability, and if it occurs inside the main PCB cover inside the refrigerator, condensation will occur, causing malfunction and failure of the refrigerator.

The object of the present invention is to prevent the malfunction and failure of the refrigerator by detecting dew condensation inside the main PCB cover of the refrigerator and removing the dew condensation by driving the heater by the detected amount in view of the conventional problems as described above. The present invention provides a device for preventing dew condensation on a refrigerator PCB.

1 is a schematic circuit diagram of an apparatus for preventing dew formation of a refrigerator PCB according to the present invention;

2 is a flowchart for explaining the present invention.

<Description of the code | symbol about the principal part of drawing>

10 ... bridge circuit 20 ... inverting amplifier

30 ... driving circuit 40 ... first transistor

50 ... buzzer sound generator 60 ... display unit

70 ... microcom 80 ... second transistor

90 ... relay 100 ... heater

110 ... heater drive

The apparatus for preventing dew condensation of the refrigerator PCB of the present invention, which achieves the above object, includes a first thermistor for detecting humidity of the outside air of the refrigerator, and a second thermistor for sensing humidity of the inside of the refrigerator to maintain equilibrium by volume resistance. Circuits; An inverting amplifier for outputting a high signal when the voltage output corresponding to the humidity detected by the second thermistor is less than or equal to a predetermined reference voltage; A microcomputer for outputting a predetermined control signal corresponding to the magnitude of the applied voltage when the voltage output from the inverting amplifier is applied; The relay is operated when the control signal is output from the microcomputer and the heater driving unit for operating the heater to correspond to the magnitude of the voltage.

According to the above-described feature of the present invention, the dew condensation preventing device of the refrigerator PCB of the present invention detects the dew condensation inside the refrigerator main PCB cover and drives the heater by a detected amount, thereby preventing malfunction and failure of the refrigerator due to the dew condensation. Will be prevented.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the apparatus for preventing dew condensation of the refrigerator PCB according to the present invention.

Dew condensation preventing device of the refrigerator PCB according to the present invention, referring to Figure 1, the first thermistor (R1) for sensing the humidity outside the refrigerator, the second thermistor (R2) for sensing the humidity inside the refrigerator, volume resistance A bridge circuit (10) adapted to maintain balance by (R3, R4);

An inverting amplifier 20 for outputting a high signal when the voltage output corresponding to the humidity detected by the second thermistor R2 is equal to or less than a predetermined reference voltage;

The driving circuit 30 includes a first transistor 40 that is turned on when the high signal of the inverting amplifier 20 is output, and a buzzer sound generation unit 50 and a display unit 60 that are operated when the first transistor 40 is turned on. )Wow;

A microcomputer 70 for outputting a predetermined control signal corresponding to the magnitude of the applied voltage when the voltage output from the inverting amplifier 20 is applied;

When the control signal is output from the microcomputer 70, the relay 90 includes a heater driving unit 110 for operating the heater 100 to correspond to the magnitude of the voltage.

In more detail, the bridge circuit 10 is a temperature and humidity detection circuit. The first thermistor R1 senses dry air outside the refrigerator, and the second thermistor R2 measures the temperature. Detect the air in the main printed circuit board (PCB).

The first and second thermistors R1 and R2 are semiconductor elements sintered by various combinations of oxides such as manganese, nickel, copper, cobalt, chromium, iron, and the like. In other words, when the temperature rises, the resistance value decreases inversely.

In addition, the third resistor R3 and the fourth resistor R4 are volume resistors (Balance) to adjust the resistance value to flow a certain amount of current to the first and second thermistors (R1, R2) and warmer than the air temperature. Will be set.

The operation of the bridge circuit 10 having such a configuration is as follows.

The output voltage Vout is the voltage between the terminal ① and the terminal ③, and the input voltage Vin is the voltage between the terminal ④ and the terminal ②.

Output voltage Vout = V1-V2 ...... (1)

V1 = R1 × I1

V2 = R2 × I2 ............... (2)

I1 = Vin / (R1 + R4)

I2 = Vin / (R2 + R3) .......... (3)

First, substituting equation (3) into equation (2)

V1 = R1 × Vin / (R1 + R4)

V2 = R2 × Vin / (R2 + R3) ....... (4)

Next, substituting equation (4) into equation (1)

Vout = R1 x Vin / (R1 + R4)-R2 x Vin / (R2 + R3).

Therefore, when the resistance of the second thermistor R2 changes in accordance with the change in temperature / humidity, the output voltage Vout changes.

On the other hand, the inverting amplifier 20 is a comparison circuit, where V1 is a voltage by reference temperature / humidity, V2 is a voltage by detection temperature / humidity, and the seventh resistor R7 is a reference voltage generating resistance.

Therefore, when the humidity is low, the bridge circuit 10 is balanced (when V1-V2? 0), that is, when the input voltage VIN is higher than the reference voltage Vref, the output voltage Vout becomes negative. Does not occur.

However, the reference voltage Vref is always set higher than the input voltage VIN.

When the humidity is high, the thermal conductivity becomes large and the resistance of the second thermistor R2 changes so that the balance of the bridge circuit 10 is broken (when V1-V2> 0), that is, the input voltage VIN becomes the reference voltage ( If it is lower than Vref), the output terminal becomes (+) voltage and output voltage Vout occurs.

In the driving circuit 30, when the output terminal of the inverting amplifier 20 becomes a positive voltage, the first transistor 40 is turned on. When the first transistor 40 is operated, the buzzer sound generating unit 50 and The display unit 60 is operated to output an alarm sound.

Therefore, when dew condensation is detected by the second thermistor R2, an alarm sound is generated to notify the user.

Meanwhile, when an output voltage is generated in the inverting amplifier 20, the detected voltage is applied to the microcomputer 70, and the microcomputer 70 outputs a heating signal by the amount of the applied voltage.

When the heating signal is output from the microcomputer 70, the second transistor 80 is turned on to operate the relay 90.

During operation of the relay 90, the heater (insulation object) 100 mounted on the main PCB cover is operated to remove dew.

Next, a detailed description will be given with reference to a flowchart of FIG. 2 attached to an operation process of an apparatus for preventing dew condensation of a refrigerator PCB according to a preferred embodiment of the present invention including the above-described configuration unit.

First, the dew condensation detection voltage of the refrigerator main PCB is input. (Vout = V1-V2) (step 200)

At this time, if V1-V2> 0, that is, if the voltage by the predetermined reference temperature / humidity is greater than the voltage by the detection temperature / humidity (step 210), the microcomputer detects the heating signal by determining that it is dewy. Step 220)

Subsequently, the transistor is turned on, and thus the condensation alarm sound generating unit is operated to emit the LED along with the buzzer sound.

Next, the heating signal set by the magnitude of the detected voltage is applied to the heater driving unit (step 230).

It is determined whether the time when the alarm sound generator is operated and the time when the heater is operated have passed the preset time (step 240). When the set time has elapsed, the alarm sound and the heater are driven off (step 250).

The heating signal is not detected for a predetermined time after the heating signal is turned off (step 260).

As described above, according to the present invention, by detecting the dew condensation in the main PCB cover of the refrigerator and driving the heater by the detected amount to remove the dew condensation to prevent the malfunction and failure of the refrigerator due to the dew condensation in advance. do.

Claims (1)

A bridge thermistor having a first thermistor for sensing the humidity of the outside air of the refrigerator and a second thermistor for sensing the humidity of the interior of the refrigerator to maintain equilibrium by volume resistance; An inverting amplifier for outputting a high signal when the voltage output corresponding to the humidity detected by the second thermistor is less than or equal to a predetermined reference voltage; A microcomputer that outputs a predetermined control signal to correspond to the magnitude of the applied voltage when the voltage output from the inverting amplifier is applied; The apparatus for preventing dew condensation of the refrigerator PCB, characterized in that it comprises a heater driving unit for operating the heater to correspond to the magnitude of the voltage when the relay outputs the control signal from the microcomputer.