KR19990055317A - Monitor power saving circuit - Google Patents

Abstract

The present invention relates to a power saving circuit of a monitor to save power consumption of the monitor, comprising: a main transformer receiving a DC voltage output from a DC power supply unit and generating driving power required by each part of the monitor; An auxiliary transformer which receives a DC voltage output from the DC power supply unit and generates a microcomputer driving power required by a microcomputer when a monitor performs a power saving mode; A control IC for outputting a PWM control signal applied to the main transformer and the auxiliary transformer; A main power transistor which receives the PWM control signal output from the control IC and switches the DC voltage applied to the main transformer; An auxiliary power transistor configured to receive the PWM control signal output from the control IC and switch the DC voltage applied to the auxiliary transformer; And a switching unit outputting the PWM control signal to a main power transistor or an auxiliary power transistor under the control of the microcomputer.

Therefore, the present invention can implement the power supply of the monitor driven by the power consumption of less than the rated power in the power saving mode by supplying the necessary power through the auxiliary power transistor and the auxiliary transformer with less power consumption when the monitor power saving mode. It has an effect.

Description

A circuit for power saving mode in a monitor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for a monitor, and more particularly, to a power saving circuit for a monitor, which saves power consumption of the monitor.

In general, a monitor is a device that receives information from a computer video card and a synchronization signal and displays information on a CRT screen. The monitor includes a video system for processing a video signal, a deflection system for vertical and horizontal deflection, and a power supply. It consists of a system.

Here, the power supply system of the monitor plays a role of properly supplying the voltage required in each part of the monitor, and the related technology is SMPS (smaller, lighter and more efficient than the linear power supply). Switching mode power supply (Switched Mode Power Supply) is developing rapidly.

FIG. 1 illustrates a general conventional switching power supply circuit (SMPS), which includes a DC power supply 110, a transformer 120, a power transistor 130, a control IC 140, and a voltage feedback unit. And a power saving mode execution unit 160.

Referring to FIG. 1, a circuit operation of a general switching power supply (SMPS) is described. First, when 100 V or 220 V commercial AC power is applied through a fuse, the line filters L1 and L2 and the capacitors C1, C2, and C3 are By removing the noise introduced through the AC power by the L-C resonant action, the high frequency noise generated while the bridge diode D1 and the control IC 140 are operated is blocked from traveling outside the AC input line.

Meanwhile, the AC voltage passing through the line filters L1 and L2 and the capacitors C1, C2 and C3 is rectified by the bridge diode D1 and smoothed in the smoothing capacitor C4 through the inrush current preventing resistor Rs. DC voltage ( V _i ) And then applied to the primary winding of transformer 120. At the same time, the rectified voltage rectified by the bridge diode D1 is applied to the control IC 140. V _cc Start resistance at R _g ) Is applied to operate the control IC 140, and the power transistor 130 is turned on / off by the control signal output from the control IC 140.

That is, the DC voltage ( V _i ) Is applied, the direct current voltage ( V _i Power supply of the control IC 140 as V _cc ) Reaches the starting voltage, the control IC 140 is operated to generate a PWM control signal, and the power transistor 130 is turned on / off by this PWM control signal. When the power transistor 130 maintains the 'on' state for a predetermined time according to the oscillator cycle in the control IC 140 and transitions to the 'off' state, the power transistor 130 is induced from the primary winding of the transformer 120 to the secondary winding. Induced electromotive force is generated.

In this case, the transformer 120 outputs an AC voltage required by the secondary winding by the PWM control signal. By repeating the above operation, the AC voltage output from the secondary winding of the transformer 120 is converted into a DC voltage through a diode and a capacitor. V _o, V _om Is converted to). When the transformer 120 operates normally, the voltage output from the tertiary winding of the transformer is controlled by the control IC 140. V _cc However, it is applied to the control IC 140 to enable the normal operation.

However, the direct current voltage output from the transformer 120 ( V _o, V _om When the voltage rises above the reference voltage, the circuit element may be damaged due to overvoltage, which may shorten the life of the power supply circuit. Therefore, in order to maintain the DC voltage at a constant voltage, a switching circuit generally has a voltage feedback unit. 150 is provided.

In more detail, the high potential DC voltage V _A output from the transformer 120 varies according to the input voltage of the transformer 120 or the turn-on period of the power transistor 130. When the voltage is higher than the predetermined voltage, the output terminal voltage of the error amplifier 151 is lowered so that a large amount of current flows through the light emitting part PC1 of the photo coupler. At this time, the light emitting unit PC1 emits as much light as that, and the light receiving unit PC2 of the photocoupler receives a lot of light, and the light receiving unit PC2 converts the optical signal into an electrical signal, which has a higher potential than normal. The feedback voltage Vfb is applied to the control IC 140.

In this way, when the feedback voltage is increased, the control IC 140 outputs a PWM control signal having a short on time, and induction is induced from the primary side to the secondary side of the transformer 120 as the on time of the power transistor 130 is shortened. As the electromotive force is lowered, the output DC voltage of the transformer 120 can maintain a normal voltage.

On the other hand, the general monitor is equipped with a power saving function, if the user does not input the key for a certain time, the PC does not output a horizontal synchronous signal or a vertical synchronous signal to the monitor, the microcomputer (not shown) in the active state The power saving mode execution signal is output to the power saving mode execution unit 160. The power saving mode performing unit 160 cuts off the secondary output voltage of the transformer 120 to prevent power from being applied to each circuit unit of the monitor, thereby performing a power saving function of the monitor.

Of course, even if the power saving mode is performed as described above, the 5V driving power is continuously applied to the microcomputer. When the user inputs a key, the PC detects this and outputs the horizontal synchronization signal and the vertical synchronization signal to the monitor. Release the power saving mode execution signal of the state so that power of the normal state is supplied to each part of the monitor.

However, even if the power saving mode execution unit operates as described above and the power consumed on the secondary side of the transformer is almost eliminated, power consumption continues to occur on the primary side of the transformer. Particularly, since the power transistor and the transformer have high capacity, There is a problem that occurs.

Accordingly, the present invention has been made to solve the problems of the prior art as described above, by providing an auxiliary transformer with low power consumption to drive in the power saving mode, to provide a power saving circuit of the monitor to reduce power consumption The purpose is.

The circuit of the present invention for achieving the above object, the main transformer for receiving the DC voltage output from the DC power supply unit for generating the drive power required by each part of the monitor; An auxiliary transformer which receives a DC voltage output from the DC power supply unit and generates a microcomputer driving power required by a microcomputer when a monitor performs a power saving mode; A control IC for outputting a PWM control signal applied to the main transformer and the auxiliary transformer; A main power transistor which receives the PWM control signal output from the control IC and switches the DC voltage applied to the main transformer; An auxiliary power transistor configured to receive the PWM control signal output from the control IC and switch the DC voltage applied to the auxiliary transformer; And a switching unit configured to output the PWM control signal to a main power transistor or an auxiliary power transistor under the control of the microcomputer.

1 is a circuit diagram showing a power supply circuit of a general monitor;

2 is a circuit diagram showing a power saving circuit of the monitor according to the present invention.

* Names of symbols according to the main parts of the drawings

110: DC power supply 120: main transformer

130: main power transistor 140: control IC

150: voltage feedback unit 160: power saving mode performing unit

210: relay 220: auxiliary power transistor

230: auxiliary transformer 240: relay drive unit

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

2 shows a power saving circuit of the monitor according to the present invention, which receives a DC voltage Vi output from the DC power supply unit 110 and generates a main power supply required for each part of the monitor. 120 and an auxiliary transformer 230 that receives the DC voltage Vi output from the DC power supply 110 and generates the microcomputer driving power Vcc required by the microcomputer when the monitor performs the power saving mode. A control IC 140 that outputs a PWM control signal applied to the main transformer 120 and the auxiliary transformer 230, and a direct current applied to the main transformer 120 by receiving a PWM control signal output from the control IC 140. The main power transistor 130 for switching the voltage Vi and the auxiliary power transistor 220 for receiving the PWM control signal output from the control IC 140 and switching the DC voltage Vi applied to the auxiliary transformer 230. ) And under the control of the microcomputer It consists of the main PWM control signal to the power transistor 130 or the auxiliary power transistor 220, the switching unit, and a voltage feedback section 150 and power save mode performing unit 160 for output to.

Here, the switching unit selects and outputs the PWM control signal output from the control IC 140 as the gate terminal of the main power transistor 130 or the gate terminal of the auxiliary power transistor 220 and the control of the microcomputer. The relay driver 240 is configured to receive a signal and drive the relay 210. The relay driver 240 is turned on when an active high level control signal is input from the microcomputer to allow a driving current to flow to the relay coil. A transistor Q21 and a resistor R22 for providing a flow path of a current flowing through the relay coil portion and the transistor Q21.

Operation and effects of the present invention configured as described above are as follows.

The DC voltage supply unit 110 receives the commercial AC power of 100V or 220V through the fuse to convert the DC voltage (Vi) through the resistor (Rs) and the capacitor (C4), the main transformer 120 and the auxiliary transformer It is applied to the primary winding of 230. On the other hand, the rectified voltage of the DC voltage supply unit 110 is applied to the Vcc terminal of the control IC 140 through the starting resistor (Rg) to drive the control IC 140, the control IC 140 for driving the transformer Output PWM control signal.

At this time, the microcomputer outputs a low level control signal because the microcomputer is not in the power saving mode. The current flowing from the driving power source Vcc to the relay coil part is turned off while the transistor Q21 applied through the resistor R21 is turned off. Is not formed, and the relay 210 outputs the PWM control signal of the control IC 140 to the gate terminal of the main power transistor 130.

The main power transistor 130 switches the DC voltage Vi applied to the primary side of the main transformer 120 while repeatedly turning on / off by a PWM control signal. The primary side and the secondary side of the main transformer 120 The induced electromotive force according to the turns ratio of is output from the secondary side winding of the main transformer 120 and the tertiary side winding. As such, when the main transformer 120 operates normally, the induced electromotive force output from the tertiary winding is rectified by the diode, smoothed by the capacitor, and then applied to the Vcc terminal of the control IC 140.

Meanwhile, the voltage feedback unit 150 controls the secondary output voltage of the main transformer 120 to maintain a constant level voltage. When the V _A voltage is higher than the rated voltage, the output terminal voltage of the error amplifier 151 is lowered. When a large amount of current flows through the light emitting portion PC1 of the photocoupler, and the V _A voltage is lower than the rated voltage, the output terminal voltage of the error amplifier 151 is increased to decrease the current flowing through the light emitting portion PC1 of the photocoupler.

At this time, the light emitting unit PC1 emits light in proportion to the current flowing therein, and the light receiving unit PC2 of the photo coupler receives the light, converts it into an electrical signal, and applies it to the control IC 140. When the V _A voltage is higher than the rated voltage, the feedback voltage Vfb of the control IC 140 is increased and when the V _A voltage is lower than the rated voltage, the feedback voltage of the control IC 140 is lowered. The control IC 140 outputs a PWM control signal having a short on-time when the input feedback voltage Vfb is high as described above, so that the induced electromotive force output to the secondary side of the main transformer 120 is reduced, and the feedback voltage Vfb is reduced. If low) outputs a PWM control signal with a long on-time to increase the induced electromotive force output to the secondary side of the main transformer 120.

When the power supply circuit of the monitor is normally driven as described above and the user does not input a key for a predetermined time, the monitor performs a power saving mode. In this case, the microcomputer outputs a control signal of an active high level to the relay driver 240. That is, the transistor Q21 is turned on by the high level control signal and a driving current flows through the coil unit, the resistor R22, and the transistor Q21 of the relay 210. When the driving current flows, the relay 210 The rotation of the switch portion of the control panel 340 connects the output terminal of the control IC 140 and the gate terminal of the auxiliary power transistor 220.

That is, the PWM control signal output from the control IC 140 is applied to the gate terminal of the auxiliary power transistor 220. The auxiliary power transistor 220 is repeatedly turned on / off by the PWM control signal, and thus the auxiliary transformer ( The DC voltage Vi applied to the 230 is switched to output the microcomputer driving power applied to the microcomputer from the secondary side of the auxiliary transformer 230.

At this time, since the power consumption of the auxiliary power transistor 220 and the auxiliary transformer 230 is small, the power consumption of the monitor is reduced. Of course, since the PWM control signal supplied to the main power transistor 130 is interrupted during the power saving mode of the monitor in which the auxiliary power transistor 220 and the auxiliary transformer 230 operate, the main power transistor 130 and the main transformer are blocked. 120 stops driving.

Meanwhile, in order for the monitor to resume normal operation after the power saving mode is performed, the microcomputer outputs a low level control signal. At this time, the transistor Q21 is turned off and the relay 210 outputs the main terminal and the output power of the control IC 140. The PWM control signal is applied to the main power transistor 130 by connecting the transistor 130. That is, when the monitor operates normally again, the main power transistor 130 and the main transformer 120 operate to supply the necessary power to each circuit part of the monitor.

As described above, in the power saving mode of the monitor, the 5V driving power required by the microcomputer is provided through the auxiliary power transistor 220 and the auxiliary transformer 230, which consume less power than the main power transistor 130 and the main transformer 120. Because of the power supply, the power consumption is greatly reduced in the power saving mode.

As described above, the apparatus of the present invention prevents the main power transistor and the main transformer with large power consumption from being driven when the monitor is in the power saving mode, and supplies necessary power through the auxiliary power transistor and the auxiliary transformer with low power consumption. By doing so, there is an effect that it is possible to implement a power supply device for the monitor driven with less than the rated power in the power saving mode.

Claims (3)

A main transformer receiving the DC voltage output from the DC power supply unit and generating driving power required by each unit of the monitor; An auxiliary transformer which receives a DC voltage output from the DC power supply unit and generates a microcomputer driving power required by a microcomputer when a monitor performs a power saving mode; A control IC for outputting a PWM control signal applied to the main transformer and the auxiliary transformer; A main power transistor which receives the PWM control signal output from the control IC and switches the DC voltage applied to the main transformer; An auxiliary power transistor configured to receive the PWM control signal output from the control IC and switch the DC voltage applied to the auxiliary transformer; And And a switching unit configured to output the PWM control signal to a main power transistor or an auxiliary power transistor under the control of the microcomputer. The relay of claim 1, wherein the switching unit selects and outputs a PWM control signal output from a control IC as a gate terminal of a main power transistor or a gate terminal of an auxiliary power transistor, and receives the control signal of a microcomputer to drive the relay. The power saving circuit of the monitor, characterized in that consisting of a relay drive. The relay driver of claim 2, wherein the relay driver provides a transistor to turn on when a control signal of an active high level is input from a microcomputer and to drive a driving current to the relay coil unit, and a flow path of a current flowing through the relay coil unit and the transistor. Power saving circuit of the monitor, characterized in that consisting of a resistor.