KR0170877B1 - Device of lamp for microwave oven - Google Patents

Abstract

The present invention relates to a lamp brightness stabilization device of the microwave oven to maintain a constant brightness of the lighting lamp for illuminating the cooking chamber of the microwave oven regardless of the variation of the commercial AC power supply. Lamp brightness stabilizing device of the microwave oven of the present invention is a microwave oven having an illumination lamp (5) for illuminating the interior of the cooking chamber (3), the voltage sensing unit for detecting the magnitude of the commercial AC voltage (40) ), The magnitude of the commercial AC voltage based on the detection signal provided from the lamp driver 50 and the voltage detector 40 for driving the lighting lamp 5 with the power controlled by the phase control of the AC voltage. After determining that the control unit 10 for outputting a control signal to the lamp driving unit 50 to reduce the phase angle of the commercial AC voltage so that the total amount of power applied to the lighting lamp (5).

Description

Lamp brightness stabilizer of microwave oven

1 is a perspective view showing the appearance of a general microwave oven.

2 is a control circuit diagram of the lamp brightness stabilization device of the microwave oven of the present invention.

3a to b are output waveform diagrams of main parts of the lamp brightness stabilization device of the microwave oven according to the present invention.

* Explanation of symbols for main parts of the drawings

1: main body 2: operation panel

3: cooking chamber 4: door

5: lighting lamp 10: control unit

20: constant voltage generator 30: synchronization signal generator

40: voltage sensing unit 50: lamp driving unit

LVT: Pressure Reducing Transformer BD: Bridge Diode

TR1, TR2: transistor D1, D2: diode

R1-R9: Resistor C1-C5: Capacitor

TRIAC: Triac

The present invention relates to a lamp brightness stabilization device of a microwave oven, and more particularly to a lamp brightness stabilization device of a microwave oven to maintain a constant brightness of the lighting lamp that illuminates the cooking chamber of the microwave oven, regardless of fluctuations in commercial AC power supply. will be.

As is well known, a microwave oven is a device for heating and cooking food by frictional heat generated in the process of vibrating water molecules contained in the food by high frequency electromagnetic waves.

1 is a view showing the appearance of a typical microwave oven. As shown in FIG. 1, a cooking chamber 3 having a front surface is formed in the center of the main body 1 of the microwave oven, and an operation for selecting a desired operation of the microwave oven on the left side of the front surface of the main body 1. Panel 2 is arranged. On the front of the cooking chamber 3, a door 4 made of a structure that prevents leakage of electromagnetic waves at the time of closing is rotatably installed, and an illumination lamp 5 for illuminating the inside of the cooking chamber 3 is provided. In the microwave oven having the above-described structure, the lighting lamp 5 is turned on while the heating operation is performed while the door 4 is opened or closed to allow the user to know the cooking state of the food.

However, while the commercial AC power supplied from Korea fluctuates slightly from region to region or time of use, conventionally, the lighting lamp is turned on and off in conjunction with the opening and closing of the door or the operation of the microwave oven. There was a problem that it was impossible to maintain. Furthermore, there has been a problem in that the microwave oven is in doubt due to a change in illuminance caused by a voltage change of a commercial AC power source.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides a lamp brightness stabilization device for a microwave oven to maintain a constant brightness of an illumination lamp that illuminates the cooking chamber of a microwave oven regardless of fluctuations in commercial AC power. The purpose is.

Lamp brightness stabilization device of the microwave oven of the present invention for achieving the above object is a voltage sensing unit for detecting the magnitude of the commercial AC voltage, commercial exchange in a microwave oven having a lighting lamp for largely illuminating the interior of the cooking chamber After determining the magnitude of the commercial AC voltage based on the lamp driver which drives the lighting lamp with the power controlled by the phase control of the voltage and the detection signal provided by the voltage sensing unit, the total power applied to the lighting lamp becomes constant. And a control unit for outputting a control signal for adding or subtracting a phase angle of a voltage to the lamp driver.

Hereinafter, with reference to the accompanying drawings, a configuration according to a preferred embodiment of the present invention will be described in detail. 2 is a control circuit diagram of the lamp brightness stabilization device of the microwave oven of the present invention. As shown in FIG. 2, the lamp brightness stabilizing device of the microwave oven of the present invention largely processes a commercial AC voltage to generate a DC voltage Vcc of a predetermined size for driving various electronic components constituting the device. A constant voltage generator 20, a synchronization signal generator 30 for generating a square wave signal synchronized with a frequency of a commercial AC voltage, a voltage detector 40 for detecting a magnitude of a commercial AC voltage, Phase control of the commercial AC voltage to convert the detection signal provided from the lamp driver 50 and the voltage sensor 40 for driving the lighting lamp 5 into a corresponding digital signal to the magnitude of the commercial AC voltage After determining that the control unit 10 for outputting the phase control pulse signal to the lamp driver 50 is made.

In the above configuration, the controller 10 is preferably implemented in microprocessors. The constant voltage generation unit 20 includes a reduced voltage transformer (LVT) for reducing the commercial AC voltage, a bridge diode (BD) for full-wave rectifying the reduced AC voltage, a capacitor (C1) for smoothing the full-wave rectified current, and the smoothing. It consists of a transistor TR1, a zener diode ZD1, resistors R1 and R2 and a capacitor C2 which convert the converted DC voltage into a more stable DC voltage. The synchronization signal generator 30 may include a diode D1 for half-wave rectifying the reduced AC voltage, resistors R3 and R4 for dividing the half-wave rectified pulse voltage at an appropriate ratio, and the divided pulse current voltage. And a transistor TR2 that is turned on and off to generate a square wave signal synchronized with the frequency of the commercial AC voltage. The voltage sensing unit 40 smoothes the voltage divider resistors R6 and R7 for dividing the commercial AC voltage by a predetermined ratio, the diode D2 for half-wave rectifying the divided AC voltage, and the half-wave rectified pulse voltage. And a capacitor C4 and a resistor R8, and the capacitors C3 and C5 each function as a noise filter. The lamp driver 50 includes a current limiting resistor for the gate terminal of the triac triac and triac to which the main electrode is connected between the lighting lamp 5, the lighting lamp 5, and the commercial AC voltage. It consists of a driver IC (IC) connected via R9).

Hereinafter, the operation of the lamp brightness stabilization device of the microwave oven having the above-described configuration will be described in detail. In this embodiment, the rated value of the commercial AC power supply is 220 [V].

(A)-(c) of FIG. 3 are the output waveform diagrams of the principal part of the lamp brightness stabilization apparatus of the microwave oven which concerns on this invention. First, while the commercial AC voltage is connected to the microwave oven, the lighting lamp 5 is operated while the door 4 of the microwave oven is opened or while the heating operation is performed while the door 4 is closed. Can be lit. At this point in time when the lighting lamp 5 is turned on, the control unit 10 receives the analog sensing signal output from the voltage sensing unit 40 through the corresponding terminal INT and converts the digital signal into a digital alternating current voltage. Determine the size of (AC). That is, the magnitude of the commercial AC voltage is determined after decomposing the maximum 5 [V] detection signal into a predetermined resolution, for example, 256 (8 bits), converting it into a digital signal. Next, the controller 10 outputs a pulse signal obtained by subtracting the phase angle in proportion to the magnitude of the commercial AC voltage thus determined (Pt = V ** 2 * t /). R) is kept constant, for example, as shown in (a) of FIG. 3, when the commercial AC voltage is 220 [V], the square wave signal having a duty of 50% is removed. The total amount of power supplied to the lighting lamp 5 is controlled by applying it to the gate terminal of the TRIAC On the other hand, as shown in (b) of FIG. 3, the commercial AC voltage is about 15% higher than the rated value. In the case of 253 [V], the total amount of electric power supplied to the lighting lamp 5 is controlled by applying a square wave signal having a duty of 10% to the gate terminal of the triac, and shown in FIG. As shown, when AC is 187 [V] which is about 15% lower than the rated value, it has 100% duty. The square wave signal is applied to the gate terminal of the triac to control the total amount of power supplied to the lighting lamp 5. On the other hand, the reference point for determining the phase angle is required to enable the phase control method. The controller 10 measures the time based on the level change time of the square wave signal provided from the synchronization signal generator 30, for example, every rising edge, and generates a phase control pulse signal.

According to the lamp brightness stabilization device of the microwave oven of the present invention as described above, by maintaining a constant brightness of the lighting lamp for illuminating the cooking room irrespective of the fluctuation of the commercial AC voltage, it protects the user's vision as well as There is an effect of providing a sense of stability for the operation of the microwave oven.

Claims (1)

In a microwave oven having an illumination lamp (5) for illuminating the interior of the cooking chamber (3), phase control of the voltage sensing unit (40) for detecting the magnitude of the commercial AC voltage and the commercial AC voltage Based on the detection signal provided from the lamp driver 50 and the voltage detector 40 for driving the lighting lamp 5 with the electric power, the magnitude of the commercial AC voltage is applied to the lighting lamp 5. And a control unit (10) for outputting a control signal for adjusting the phase angle of the commercial alternating current (AC) to the lamp driving unit (50) so that the total amount of power becomes constant.