KR200147221Y1 - Power control circuit for microwave oven - Google Patents

Abstract

The present invention relates to a power supply circuit for controlling a microwave oven, and a full-wave rectifier for rectifying a constant commercial power supply (AC 220 [V]) through a fixed resistor (R1) and a bridge rectifier circuit (D1, D2, D3, D4). And a first voltage divider for dividing the voltage applied from the full-wave rectifier by a parallel connection of the resistor R2 and the resistor R3, and removing and outputting the ripple of the voltage divided by the first voltage divider. A voltage output section, a constant voltage circuit section for stably maintaining the voltage output from the voltage output section, and a constant voltage input through the constant voltage circuit section to distribute the parallel voltage between the resistor R9 and the resistor R10. A voltage comparator for applying a constant signal to a voltage output unit, the voltage comparator being connected to the voltage output section; Depend on The constant voltage control unit that controls the reference voltage of the voltage circuit unit can be applied to drive power for microcomputers and other devices with commercial power (AC 220 [V]), thereby reducing the product cost of microwave ovens and improving the efficiency of product assembly. Will be.

Description

Microwave power control circuit

The present invention relates to a power supply circuit for controlling a microwave oven, and in particular, to control a microwave oven having a circuit composed of a simple element that replaces a transformer installed in a driving power supply unit for driving a microcomputer or other device. It relates to a power supply circuit.

In general, microwave ovens vibrate the water molecules contained in food by applying high voltage electricity to the high frequency oscillator of the Marknetron, and the frictional heat generated by the microwave heats the inside and outside of the food at the same time. As an electric appliance to heat, nowadays a microwave oven employing a heater to cook the grill is used to heat food by a heater together with microwaves to cook more various foods.

Such a microwave oven is installed on the bottom surface of the rectangular space inside the microwave oven body 50, as shown in Figure 1, the tray 52 is installed so that the food is evenly rotated, the body of the microwave oven (50) One side is provided with an operation panel 56 that sets each cooking function and includes start and end keys. And the door 54 of the microwave oven is provided with a see-through window 58 for checking the cooking state in the cooking chamber and a door lock safety device 60 for fixing the door 54 with the main body 50 is installed. have.

When the user wants to cook food using the microwave oven as described above, the food is first put into the cooking chamber and the food is selected through a corresponding key on the operation panel 56. That is, the start key of the operation panel 56 is set. By applying a high voltage through the high-voltage transformer magnetron emits a constant microwave through the waveguide, the food in the cooking room is heated or cooked for a set time.

On the other hand, in the operation of the microwave as described above, the microcomputer performs an operation related to cooking according to a control signal. At this time, the driving power of the microcomputer is supplied with a constant AC power through a low voltage transformer and a regulator.

That is, as shown in FIG. 2, a conventional power supply control circuit for a microwave oven is supplied with a constant AC power supply (AC 220 [V]) to the primary side and a low voltage transformer for applying a constant voltage according to the number of coil turns to the secondary side. 70 and a full wave rectifier for outputting a pulsating voltage containing a constant ripple by a full wave rectifying action by the bridge diodes D1, D2, D3, and D4 from a constant power source output from the secondary side of the low voltage transformer 70 ( 71) and a smoothing circuit section 72 for outputting a DC power supply of a predetermined level with a ripple reduced in charge / discharge operation by receiving the pulsating voltage output from the full-wave rectifying section 71; and outputted from the smoothing circuit section 72. It consists of the regulator 73 which maintains and supplies a predetermined DC power supply to a stable constant voltage.

A capacitor C2 for stabilizing the constant power output is connected to the output side of the regulator 73 and is grounded.

On the other hand, looking at the conventional operation made of such a configuration as follows. First, when a power plug is inserted into an outlet, a commercial AC power supply (AC 220 [V]) is applied as a high voltage transformer and supplied as a driving power of the magnetron. Commercial power is input into the low voltage transformer 70. Then, according to the number of coil windings on the primary and secondary sides of the low voltage transformer 70, the commercial power source is reduced to a constant power source and input to the full wave rectifying unit 71. Then, the predetermined power inputted to the full wave rectifying unit 71 is full-wave rectified through the bridge diodes D1, D2, D3, and D4, and is output to the pulsating power source with a constant ripple. At this time, the pulsating power source including the ripple is inputted to the smoothing circuit unit 72 in which the diode D5 and the smoothing capacitor C1 are arranged in parallel. Power is applied to the regulator 73. Therefore, the power output through the regulator 73 is stably output through the capacitor (C2) connected in parallel to the output terminal is to be the driving power source for the microcomputer and other elements.

However, such a conventional power control circuit for microwave ovens uses a low voltage transformer to reduce the commercial AC power input to a certain level, and the low voltage transformer used here is large in volume and size and heavy, thus destroying the PCB installed in the electrical equipment room. In addition, since the material of the low-voltage transformer itself is made of copper and iron, there is a disadvantage in that the production cost of the microwave is increased.

Therefore, the present invention has been devised to secure such disadvantages, and the circuit which applies the driving power of the microcomputer and other elements of the microwave oven can obtain the constant driving power according to the load change by using the simple element and the constant voltage circuit. It is an object of the present invention to provide a power supply circuit for controlling a stove.

The present invention for achieving this purpose is a full-wave rectifier (1) and a full-wave rectifier (1) for rectifying the constant commercial AC power supply (AC 220 [V]) through the bridge diode (D1, D2, D3, D4) Ripple of the voltage divided by the first voltage distribution stage 2 and the first voltage distribution stage 2 which distributes the voltage applied from the resistor R2 and the resistor R3 in parallel connection. Resistance voltage output section 3 to remove and output, constant voltage circuit section 4 for stably maintaining and outputting the voltage output from the voltage output section 3, and constant voltage output from the constant voltage circuit section 4 A second voltage distribution terminal 5 which distributes by parallel connection of R9 and a resistor R10 and its input terminal are connected to the constant voltage circuit section 4 and the second voltage distribution terminal 5 and compared. A voltage comparator 6 for applying a predetermined signal according to the voltage value to the voltage output unit 3, and a voltage output from the first voltage distribution terminal 2; Along and being provided with a constant-voltage control section 7 for controlling the reference voltage of the constant-voltage circuit section (4).

1 is an external configuration diagram of a typical microwave oven.

2 is a view showing a power supply circuit for controlling a conventional microwave oven.

3 is a view for explaining the operation of the control power supply circuit of the microwave oven according to the present invention.

<Explanation of symbols for main parts of drawing>

1: full-wave rectifier 2: first voltage division

3: voltage output section 4: constant voltage circuit section

5: second voltage divider 6: voltage comparison unit

7: constant voltage control unit

When the present invention is described in detail with reference to the accompanying drawings as follows.

As shown in FIG. 3, the control power supply circuit according to the present invention includes a full-wave rectifier 1 for rectifying a constant commercial AC power supply AC 220 [V] through bridge diodes D1, D2, D3, and D4. And a first voltage distribution stage (2) for distributing the voltage applied from the full-wave rectifying section (1) to a parallel connection of the resistor (R2) and the resistor (R3), and the voltage through the first voltage distribution stage (2). A voltage output section 3 for removing and outputting the ripple of the divided voltage, a constant voltage circuit section 4 for stably maintaining and outputting the voltage output from the voltage output section 3, and from the constant voltage circuit section 4 The output voltage is inputted to the second voltage divider 5, which divides the output constant voltage by the parallel connection of the resistor R9 and the resistor 10, and to the constant voltage circuit section 4 and the second voltage divider 5, respectively. A voltage comparator 6 for applying a predetermined signal to the voltage output unit 3 by connecting terminals to the voltage output unit 3, and the first voltage Depending on the output voltage comprises a constant-voltage control section 7 for controlling the reference voltage of the constant-voltage circuit section (4).

In addition, the voltage output unit 3 has a first transistor having a collector terminal connected to the first voltage distribution terminal 2, an emitter terminal connected to the constant voltage circuit unit 4, and a base terminal connected to the voltage comparator 6. Q1), a resistor R4 connected between the collector terminal and the base terminal of the first transistor Q1, and a smoothing capacitor C1 connected in parallel to the emitter terminal of the first transistor Q1. In addition, the constant voltage circuit section 4 is connected between the voltage output section 3 and the second voltage distribution terminal 5 in parallel and connected in series with a resistor R11 and a resistor R7, the resistor R11 and a resistor. The cathode terminal is connected between R7 and the anode terminal is composed of a grounded zener diode (ZD).

The non-inverting terminal (+) of the voltage comparing unit 6 is connected between the constant voltage circuit unit 4 and the constant voltage control unit 7 and its inverting terminal (-) is connected to the second voltage distribution terminal 5 and the output terminal thereof. The ruler is connected to the base end of the first transistor Q1 through a resistor R5.

In addition, the constant voltage control unit 7 is connected between the resistor (R2) and the resistor (R3) of the base terminal of the second transistor (Q2) via a resistor (R6), the collector terminal and the capacitor (C3) The resistors R8 are respectively connected in parallel and connected to the constant voltage circuit section 4, and the emitter terminal thereof is grounded.

In addition, a resistor R1 is connected to the input side of the full wave rectifying unit 1.

Here will be described in detail the present invention made of such a configuration as follows.

First, when a power plug is inserted into an outlet of a microwave oven, a commercial AC power supply (AC 220 [V]) is applied as a high voltage transformer and supplied as a driving power of a magnetron, and input driving power to the microcomputer and other elements of the microwave oven. In order to achieve this, the commercial power supply AC 220 [V] is first reduced through a resistor R1 to a predetermined level, and is uniformly supplied through the full-wave rectifying unit 1 formed of bridge diodes D1, D2, D3, and D4. The pulsation voltage containing the ripple is output. The pulsation voltage is then applied to the collector terminal of the first transistor Q1, and is divided by the resistor R2 and the resistor R3 and applied to the base terminal of the second transistor Q2. At this time, when the pulsation voltage outputted through the first voltage division stage is output at a predetermined level or higher, the base terminal of the second transistor Q2 is maintained in a high state, thereby preventing operation. Since the base end of the first transistor Q1 is in a high level by a constant signal applied through the resistor R4, the pulsation voltage containing a constant ripple is applied to the emitter end to charge and discharge the capacitor C1. The predetermined drive voltage (+24 [V]) is output through the constant voltage circuit part 4 and the 2nd voltage distribution terminal 5 in the state which the pulsation was removed by.

At this time, when the pulsation voltage applied from the full-wave rectifying unit 1 drops to a predetermined level, the first voltage distribution stage 2 is turned on from the high state to the low state. Then, the reference voltage V ₂ set in the constant voltage circuit unit 4 is inputted to the non-inverting terminal (+) of the voltage comparing unit 6 in a reduced state, wherein the voltage input to the non-inverting terminal (+) is the voltage. The voltage of the second voltage distribution terminal 5 applied to the inverting terminal (-) of the comparator 6 is lower. Therefore, the base end of the first transistor Q1 is at a low level so that the pulsation voltage output from the full-wave rectifier 1 is no longer output through the first transistor Q1.

On the other hand, when the pulsation voltage output from the full-wave rectifier 2 rises to a constant level, the base terminal of the second transistor Q2 is maintained in a high state again, so that the constant voltage circuit unit 4 maintains a constant reference voltage. do. Therefore, the base end of the first transistor Q1 goes from a low state to a high state by a signal output from the voltage comparator 6, so that the pulsation voltage output from the full-wave rectifying unit 2 is the first transistor Q and the capacitor. Through (C1) is applied to the regulator not shown in the voltage state with the ripple removed. In addition, as the load current increases, the output voltage thereof decreases, so that the voltage input to the inverting terminal (-) of the voltage comparator 6 through the second voltage distribution stage 5 decreases. Then, the time for which the output voltage of the voltage comparator 6 is kept high increases to maintain the output voltage constant.

As such, the present invention can reduce the product cost of the microwave oven and increase the efficiency of product assembly by constructing a circuit capable of applying a driving voltage to a microcomputer or other device using simple devices instead of a low voltage transformer.

Claims (5)

A full-wave rectifier (1) for reducing the voltage and rectifying the constant commercial AC power supply (AC 220 [V]) through the resistor (R1) and bridge diodes (D1, D2, D3, D4), and the full-wave rectifier (1) The first voltage distribution stage 2 which distributes the applied voltage from the resistor R2 and the resistor R3 in parallel connection and removes the ripple of the voltage divided by the first voltage distribution stage 2. The voltage output section 3 outputting the voltage output section 3, the constant voltage circuit section 4 stably maintaining and outputting the voltage output from the voltage output section 3, and the constant voltage output from the constant voltage circuit section 4 The second voltage distribution terminal 5 which distributes by parallel connection of R9) and the resistor R10, and its input terminal are connected to the constant voltage circuit section 4 and the second voltage distribution terminal 5 and compared with each other. The constant voltage circuit according to the voltage comparator 6 for applying a predetermined signal according to the value to the voltage output section 3 and the voltage output from the first voltage distribution terminal 2. A power supply circuit for controlling a microwave, characterized by comprising a constant voltage control unit (7) for controlling a reference voltage of the unit (4). 2. The voltage output section (3) according to claim 1, wherein a collector end is connected to the first voltage distribution stage (2), the emitter end thereof is connected to the constant voltage circuit section (4), and the base end is connected to the voltage comparing section (6). The first transistor Q1, the resistor R4 connected between the collector terminal and the base terminal of the first transistor Q1, and the smoothing capacitor grounded in parallel to the emitter terminal of the first transistor Q1. Power supply circuit for controlling a microwave, characterized in that consisting of C1). A resistor (R11) and a resistor (R7) according to claim 1, wherein the constant voltage circuit section (4) is connected in parallel between the voltage output section (3) and the second voltage distribution terminal (5). A cathode end is connected between an R11 and a resistor R7, and the anode end is a grounded zener diode ZD. The constant voltage control unit (7) of claim 1, wherein the constant voltage control unit (7) and the second transistor (Q2) having a base terminal connected to the first voltage distribution terminal (2) via a resistor (R6) and the second transistor (Q2). A power supply circuit for controlling a microwave oven, comprising: a capacitor (C3) and a resistor (R8) connected in parallel with each other at a collector end of the same and connected to a constant voltage circuit unit (4). The non-inverting terminal (+) of the voltage comparator (6) is connected between the constant voltage circuit section (4) and the constant voltage control section (7), and its inverting terminal (-) is the second voltage distribution stage (5). And an output terminal thereof connected to a base terminal of the first transistor Q1 through a resistor R5.