KR20000014583U - Ultra Low Power Circuit of Monitor Power Supply - Google Patents

Abstract

The present invention relates to a super power saving circuit of the monitor power supply that can minimize the power consumption even in the OFF mode in the monitor.

The circuit of the present invention rectifies and converts the AC power into DC, and then switches the DC power according to the PWM control signal of the power control element to induce a voltage on the secondary winding side of the power transformer, and to the secondary winding of the power transformer. In a monitor power supply circuit in which a induced voltage is fed back to a power supply control element through a photocoupler to supply power according to a mode, a Zener diode (ZD1) connected in parallel to a Vcc voltage winding of a power supply transformer to make a constant Vcc voltage Wow; Division resistor circuits R20 and R21 connected in parallel to the zener diodes ZD1 to divide the Vcc voltage; A feedback capacitor (C _FB ) connected between the emitter of the transistor and the ground and connected with the photocoupler to provide a feedback voltage to the feedback terminal of the power supply control element; And a transistor Q20 for charging the feedback capacitor when the division voltage of the division resistor circuit is applied to the base and turned on according to the feedback voltage.

Therefore, according to the present invention, the power consumption can be further reduced by controlling to stop or continue the switching operation in the off mode.

Description

POWER SAVING CIRCUIT OF A MONITOR POWER SUPPLY

The present invention relates to a power supply control technology for a monitor, and more particularly, to an ultra-power saving circuit of a monitor power supply that can minimize power consumption even in an OFF mode.

In general, Display Power Management Signaling (DPMS) is a type of office equipment that is regulated by the Video Electronics Standards Association (VESA), a video equipment standardization organization, to save energy by reducing the waste of power consumed in the most widely used monitors. A power control related technology.

In the DPMS, as shown in Table 1, four states are defined according to the state of APM (Advanced Power Management) operated in the computer main body, and horizontal and vertical synchronization signals are used to identify them. Here, APM is a computer power management process defined by Microsoft and IBM.

condition signal Required Power saving degree Normal recovery time Horizontal synchronization Vertical synchronization video On has exist has exist Normal input compulsion Saving - Standby none has exist Blanking option small short Suspend has exist none Blanking compulsion versus Kim off none none Blanking compulsion maximum -

As shown in Table 1, the state (or mode) in the DPMS is on (on), standby (stand-by), suspend (suspend), off (off), dual on (on), suspend The suspend, off state must be at least accepted.

In the on state (mode), there are both a horizontal synchronous signal and a vertical synchronous signal input from the computer through the D-sub, and the video signal is normally input and displayed on the screen. In standby mode (mode), there is no horizontal synchronous signal input from the computer through D-sub, only vertical synchronous signal, and the video signal is blanked so that nothing is displayed on the screen. This is a state of saving. In the suspend state (mode), there is a horizontal synchronous signal input from the computer through the D-sub, no vertical synchronous signal, and the video signal is blanked so that nothing is displayed on the screen. It is a state of saving. The off state (mode) is a state in which the power is off, there is no vertical and horizontal synchronization signal, the video signal is blanked, and the power is maximized.

In this way, the state of the DPMS is determined according to the synchronization signal input from the computer, and power can be saved by turning off or on the power of the corresponding part according to each state.

FIG. 1 is a circuit diagram illustrating a power supply circuit of a general monitor, which includes a DC power supply 110, a power transformer 120, a switching device 130, a power control device 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 resonance, the high frequency noise generated while the bridge diode D1 and the power control element 140 are operated is blocked from going 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. After the conversion to the DC voltage (Vi), it is applied to the primary winding of the power supply transformer (120). At the same time, the DC voltage Vi is applied to the Vcc terminal of the power supply control element via the starting resistors R1 and R2. As a result, the PWM is output from the power supply control element 140 while the power supply control element 140 is operated. The switching element 130 is turned on / off by the control signal.

That is, when the power supply control element is operated by the DC voltage Vi to output the PWM control signal, the switching element 130 is turned on / off by this PWM control signal. When the switching device 130 maintains the 'on' state for a predetermined time according to the oscillator cycle in the power supply control element and then transitions to the 'off' state, the induced electromotive force is induced from the primary winding of the power supply 120 to the secondary winding. This will occur. That is, the power transformer 120 outputs an AC voltage required by each circuit unit of the monitor through the secondary winding by the PWM control signal.

As such, when the power transformer 120 operates normally, the AC voltage output through the secondary winding of the power transformer is converted into a DC voltage through a diode and a capacitor. At this time, the voltage output from the tertiary winding of the power transformer 120 It is applied to the Vcc terminal of the power control device 140 so that the power control device can operate normally.

However, the conventional monitor power supply circuit consumes more than 5W even in the OFF mode, so it is required to develop an ultra-low power circuit that can reduce power consumption to less than 3W in the off mode.

Accordingly, an object of the present invention is to provide an ultra-power saving circuit of a monitor power supply that can be minimized in order to minimize the power consumption in the off mode.

In order to achieve the above object, the circuit of the present invention rectifies and converts AC power into DC, and then switches the DC power according to the PWM control signal of the power control element to induce voltage on the secondary winding side of the power transformer. In the monitor power supply circuit for supplying power in accordance with the mode by feeding back the voltage induced in the secondary winding of the power transformer to the power control element through a photocoupler, the Vcc voltage of the power transformer is connected in parallel to the Vcc winding A zener diode which makes the voltage constant; A division resistor circuit connected to the zener diodes in parallel to divide the Vcc voltage; A feedback capacitor connected between the emitter of the transistor and the ground and connected to the photocoupler to provide a feedback voltage to the feedback terminal of the power control element; And the transistor for charging the feedback capacitor when the division voltage of the division resistor circuit is applied to the base and turned on according to the feedback voltage.

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

2 is a circuit diagram illustrating a super power saving circuit of a monitor power supply according to the present invention.

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

110: DC power supply unit 120: power transformer

130: switching element 140: power control element

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

ZD1: Zener Diode Q20: Transistor

C _FB : Feedback Capacitor

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

2 is a circuit diagram illustrating a super power saving circuit of a monitor power supply to which the present invention is applied. Referring to FIG. 2, the circuit of the present invention includes a Zener diode ZD1 and a Zener diode ZD1 connected in parallel through a rectifying diode and a resistor to a winding for providing a Vcc voltage in the secondary winding of the power supply 120. Capacitor C20 connected in parallel to the capacitor C), the split resistor circuits R20 and R21 connected in parallel to the capacitor 20 to divide the Vcc voltage, and the base is connected to the common connection point of the split resistor circuit through the diode D20. The transistor Q20 connected to the collector through the variable resistor VR20 at the Vcc voltage terminal and the emitter of the transistor Q20 and the ground to supply the feedback charging voltage Vfb to the power supply control element 140. It consists of a capacitor (C _FB ) provided to the feedback terminal (Vfb) of.

In FIG. 2, the rated voltage of the zener diode ZD1 is set equal to or lower than about 1 V of the Vcc winding voltage. Then, the resistance values of the split resistors R20 and R21 are determined such that the voltage Vr of the node is about 2 to 2.5V.

Next, look at the operation of the circuit of the present invention configured as described above are as follows.

Voltage (Vr-) minus drop voltage (approximately 0.7 x 2 = 1.4 V) between the emitter-base of one diode D20 and transistor Q20 from the voltage Vr of the node set as split resistors R20 and R21. When the feedback voltage Vfb of the capacitor C _FB is lower than the voltage of 1.4 V, the transistor Q20 is turned on to flow a current through the variable resistor VR20 to the feedback capacitor C _FB to increase the Vfb voltage. The PWM signal duty of the control element 140 is increased. Therefore, due to the increased duty, a lot of energy is transferred to the secondary side of the power transformer 120, so that the voltage to be regulated is increased. As the secondary voltage of the power supply 120 increases, the current flowing through the photocoupler (PC1, PC2 in FIG. 1) increases, and the feedback voltage Vfb drops to about 0.3V at a moment greater than the current flowing therein. The switching operation of the switching device (FIG. 1 130) is stopped. As the switching operation is stopped, the secondary voltage of the power supply transformer 120 gradually decreases, and while the current flowing through the photocouplers PC1 and PC2 decreases, the feedback voltage Vfb increases and switching is repeated. As such an operation is repeated, power consumption can be reduced as compared with conventional circuits.

On the other hand, when the screen is turned on (normal operation mode), the feedback voltage Vfb is increased so that the transistor Q20 is in a blocking state and thus does not affect the feedback loop.

As described above, according to the present invention, the voltage of the feedback capacitor is changed by the on / off of the transistor in the off mode, and accordingly, the power control element stops or continues the switching operation so that the power consumed as a whole is further increased. There is an effect that can be reduced.

Claims (1)

After rectifying AC power and converting it to DC, switch DC power according to PWM control signal of power control element to induce voltage on secondary winding side of power transformer, and convert voltage induced on secondary winding of power transformer to photocoupler. In the monitor power supply circuit for supplying power in accordance with the mode by feeding back to the power control element through; A Zener diode (ZD1) connected in parallel to the Vcc voltage winding of the power supply transformer to make the Vcc voltage constant; Division resistor circuits R20 and R21 connected in parallel to the zener diodes ZD1 to divide a Vcc voltage; A feedback capacitor (C _FB ) connected between the emitter of the transistor and the ground and connected to the photocoupler to provide a feedback voltage to a feedback terminal of the power control element; And And a transistor (Q20) for charging the feedback capacitor when the division voltage of the division resistor circuit is applied to the base and turned on according to the feedback voltage.