KR20010010485A - A power-saving circuit of a display system - Google Patents

Abstract

PURPOSE: A power-savings circuit for a display device is provided to make an SMPS(Switched Mode Power Supply) circuit not generate every power voltages necessary for each circuit of the display device in an off mode. CONSTITUTION: A capacitor(Cs) is charged at a predetermined voltage. A power controller(10) generates a PWM(Pulse Width Modulation) control signal by a charging voltage(Vcs) of the capacitor(Cs) in an initialization operation, and controls warming-up voltage to be supplied to each circuit. After the initialization operation, the power controller(10) generates the PWM control signal by a feedback voltage(Vfb), and controls rated voltage to be supplied to each circuit. If the capacitor(Cs) is not charged, the power controller(10) suspends the generation of the PWM control signal. A microcomputer(20) outputs an off signal in an off mode. If the off signal is inputted, a power-savings circuit(30) discharges the capacitor(Cs).

Description

A power-saving circuit of a display system

The present invention relates to a power saving circuit of a display device.

More particularly, the present invention relates to a power saving circuit of a display device, which reduces power consumption by cutting off power supply voltage in an off mode.

In general, when a user does not use a personal computer (PC) without turning off the power, the microcomputer built into the PC recognizes this and reduces power consumption to 5 W or less. Contrary to this, when the user wants to use the PC again, the previous screen is automatically displayed on the monitor immediately.

FIG. 1 is a circuit diagram showing a power saving circuit of a general monitor. The switching power supply circuit 1 supplies a power supply voltage necessary for operating each part of the monitor such as a horizontal / vertical deflection unit and a video amplifier and a heater.

In general, power-saving monitors are implemented with Display Power Management System (DPMS) according to the standards of the Korean Association of Image Electronics Standards (hereinafter referred to as VESA), which are the normal mode, suspend mode, and off mode. It operates in the) mode and is controlled by the software of the microcomputer embedded in the PC.

PC microcomputer Monitor microcomputer mode Horizontal Sync Signal (H.SYNC) Vertical Synchronization Signal (V.SYNC) Suspension signal (SUS) OFF signal (OFF) normal Output (O) Output (O) High level High level Suspend Output (X) Output (O) Output (O) Output (X) Low level High level off Output (X) Output (X) Low level Low level

Referring to Table 1 and FIG. 1, the general monitor operation is divided into normal mode / suspend mode / off mode.

1. In normal mode

The PC microcomputer outputs both horizontal and vertical synchronizing signals (H.sync and V.sync) to the monitor microcomputer 2, whereby the monitor microcomputer 2 outputs the suspend signal SUS and the high level suspend. The signal OFF is output to the power saving means 3.

The power saving means 3, which receives the suspend signal SUS and the OFF signal OFF of the constant high level, supplies the power supply voltage of the rated power output from the switching power supply circuit 1 to each of the monitor circuits as it is, and supplies the monitor circuits. Operate normally.

2. In suspend mode

When there is no input on the keyboard for a predetermined time (usually 1,2 minutes), the PC microcomputer sends only one of the horizontal sync signal and the vertical sync signal (H.sync and V.sync) to the monitor microcomputer 2. Output

Accordingly, the monitor microcomputer 2 outputs the low level suspend signal SUS and the high level off signal OFF to the power saving means 3, whereby the power saving means 3 switches the switching power supply circuit 1. ), Cut off the power supply voltage to each part of the monitor circuit.

At this time, since the heater is not easily heated, even when the power saving function is performed on the monitor, the heater may be quickly switched when the normal mode is switched only when the rated voltage (6.3 V) is applied.

That is, in suspend mode, all circuit operations are stopped and only the minimum required power supply (6.3V) is driven to reduce the power consumption of the monitor.

3. In off mode

The PC microcomputer does not output both the horizontal synchronizing signal and the vertical synchronizing signal (H.sync and V.sync) to the monitor microcomputer 2, so that the monitor microcomputer 2 is a low level suspending signal ( SUS) and the OFF signal OFF are outputted to the power saving means 3.

When the low power suspend signal SUS and the OFF signal OFF are input, the power saving means 3 cuts off the power supply voltage supplied to each part of the monitor circuit from the switching power supply circuit 1, and in the suspend mode. Unlike this also cuts off the power supply voltage (6.3V) supplied to the heater (Heater).

That is, when the low-level suspend signal SUS is applied to the base terminal of the second transistor Q22 through the resistor R24, the second transistor Q22 is turned off, and the second transistor Q22 is turned on. When turned off, the emitter potential of the first transistor Q21 is equal to the base potential, and the first transistor Q21 is turned off, so that a predetermined power supply voltage 13V output from the switching power supply circuit 1 is horizontal. It is not supplied to the deflection circuit.

Meanwhile, when the low level off signal OFF is applied to the base terminal of the fourth transistor Q24 through the resistor R28, the fourth transistor Q24 is turned off and the emitter potential of the third transistor Q23 is turned off. When the and the base potentials are the same, the third transistor Q23 is turned off, and accordingly, the predetermined power supply voltage 6.3V output from the switching power supply circuit 1 is not supplied to the heater.

As described above, the PC-separated monitor, in which the PC and the monitor are separated, prevents the output voltage of the switching power supply circuit 1 from being supplied to each circuit part in the off mode so as to reduce the power consumption to 5 W or less to satisfy the VESA standard. It is.

Compared with the PC detachable monitor as described above, the integrated monitor of the PC has the advantage of less external wire, concise and easy to move, so the development and aspect of the integrated monitor of the PC is expected to increase in the future.

However, the all-in-one PC monitor consumes about 4W of power from the PC itself in the off mode, and consumes about 4W of power from the monitor itself, so that the total power consumption reaches about 8W. There is a problem that violates the VESA standard.

Accordingly, an object of the present invention is to provide a power saving circuit of a display apparatus to reduce power consumption of a monitor by blocking the generation of a power supply voltage in an off mode.

The power saving circuit of the display device according to the present invention for achieving the above object,

Charging means for charging a predetermined voltage;

In the initial operation, a PWM control signal is generated by the charging voltage of the charging means to control the warm-up voltage to be supplied to each circuit, and after the initial operation, the PWM control signal is generated by the feedback voltage to supply the rated voltage to each circuit. Power control means for controlling and stopping generation of the PWM control signal when the charging means is discharged;

A microcomputer which outputs an off signal in the off mode;

And a power saving means for discharging the charging means when an off signal is input from the microcomputer.

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

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

* Names of symbols for main parts of the drawings

10: power control means 20: microprocessor

30: power saving means 31: switching means

32: transfer means Cs: charging means

Q11: switching transistor PC1: light emitting diode

PC2: Receiving Transistors COM: PWM Comparator

D11, D12, D13: Diodes R11, R12, R13, R14, R15: Resistance

Hereinafter, a power saving circuit of a monitor according to the present invention will be described in detail with reference to the accompanying drawings.

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

As shown in FIG. 2, the power saving circuit of the monitor according to the present invention includes: charging means Cs for charging a predetermined voltage; In the initial operation, the PWM control signal is generated by the charging voltage Vcs of the charging means Cs to control the warm-up voltage to be supplied to each circuit, and after the initial operation, the PWM control signal is generated by the feedback voltage Vfb. Power supply control means (10) for controlling the supply of the rated voltage to each circuit portion and stopping the generation of the PWM control signal when the charging means (Cs) is discharged; A microcomputer 20 which outputs an off signal OFF in the off mode; When the OFF signal OFF is input from the microcomputer 20, the power saving means 30 discharges the charging means Cs.

Here, the power saving means 30 is composed of switching means 31 for switching on / off by the off signal OFF to discharge the charging means Cs, and the switching means 31 is a transmission means ( It operates by receiving the OFF signal (OFF) via 32).

In addition, the charging means (Cs) is composed of a capacitor having one end connected to the power control means 10 and the other end is grounded, the switching means 31 is the base end through the resistor (R11) NPN-type switching transistor Q11 is connected to the power supply control means 10 and the capacitor Cs in parallel and the emitter terminal is grounded when the OFF signal is received. 32 is a light emitting diode PC1 whose anode end receives the OFF signal OFF through a resistor R11 and whose cathode end is grounded; A light receiving terminal having a collector terminal connected to a voltage source through a resistor R12, an emitter terminal grounded differently from the light emitting diode PC1, and a base terminal of the NPN type switching transistor Q11 connected in parallel between the voltage source and the collector terminal. It consists of the transistor PC2.

In general, the power circuit serves to properly supply the voltage required for each part of the monitor. The technology related to the SMPS (Switched Mode Power Supply) is smaller, lighter and more efficient than the Linear Power Supply. This is a rapidly developing trend.

Referring to Figure 1 briefly look at the operating principle of the switching power supply circuit (SMPS) commonly applied to the monitor, after converting the commercial AC voltage input from the external DC voltage (Vi) after the primary coil of the transformer (T) Induced electromotive force in the secondary coil of the transformer T by supplying to one end, connecting the power transistor Q to the other end of the secondary coil of the transformer T, and turning on / off the power transistor Q After generating (Vs, Vsm), the induced electromotive force (Vs, Vsm) is converted into DC voltages (Vo, Vom) and supplied to each circuit.

At this time, the power control means 10 generates a PWM control signal by comparing the feedback voltage Vfb with the reference voltage Vref, and then supplies the PWM control signal to the power transistor Q to supply the power transistor Q. Control to turn on / off.

At this time, if the maximum (rated) current output from the switching power supply circuit (SMPS) is supplied to the monitor circuit as it is during initial operation of the monitor, the circuit will be severely stressed. It is necessary to supply a warm-up voltage lower than the rated voltage to the circuit, which is called a soft start function, and the power supply control unit 10 according to the present invention includes a soft start circuit for performing this function.

That is, in the initial operation, the capacitor Cs starts to be charged by the 1 mA current source, the 5 V voltage source, and the resistor R13.

When the charge voltage Vcs of the capacitor Cs becomes 3V or more, the diode D11 is turned off, so that no more current flows from the 1mA current source to the capacitor Cs, where the capacitor Cs is a resistor. It is charged up to 5V via (R13).

As a result, the inverting terminal voltage of the PWM comparator COM is slowly increased by 1/3 of the charge voltage Vcs of the capacitor Cs until the diode D11 is turned off.

Accordingly, the current flowing through the power transistor Q also slowly rises along the inverting terminal voltage of the PWM comparator COM.

Since the diode D11 is turned off when the charging voltage Vcs of the capacitor Cs becomes 3V or more, the inverting terminal voltage of the PWM comparator COM is no longer the charging voltage Vcs of the capacitor Cs. Follow the feedback voltage (Vfb) without following.

In shutdown or protection operation, the capacitor Cs is discharged so that it can be charged from 0V during reoperation.

Looking at the operation of the circuit according to the invention divided into the normal mode and the off mode as follows.

At this time, the microcomputer 20 outputs an OFF signal OFF of a high level (5V) in a normal mode and an OFF signal OFF of a low level (0V) in an off mode.

1.In normal mode

When the high level off signal OFF is input to the light emitting diode PC1 of the photo coupler 32 through the resistor R11, the light emitting diode PC1 emits light, and thus the light receiving transistor PC2 As such, a predetermined voltage flows to ground through the resistor R12 and the light receiving transistor PC2.

As a result, a voltage close to 0 V is applied to the base end of the NPN type switching transistor Q11, so that the NPN type switching transistor Q11 is switched off, so that the power supply control means 10 operates normally.

That is, the state in which the 5V voltage is charged in the capacitor Cs is maintained.

2. In off mode

When the low level off signal OFF is input to the light emitting diode PC1 of the photo coupler 32 through the resistor R11, the light emitting diode PC1 does not emit light, and thus the light receiving transistor PC2 is applied. Is not operated, a predetermined voltage is applied to the base terminal of the NPN type switching transistor Q11 through the resistor R12.

Accordingly, since the NPN type switching transistor Q11 is switched on, the 5V voltage charged in the capacitor Cs is discharged through the NPN type switching transistor Q11, and the feedback voltage Vfb is also an NPN type switching transistor. Discharged through Q11.

Accordingly, no voltage is applied to the inverting terminal of the PWM comparator COM so that a PWM control signal is not generated and the PWM control signal is not supplied to the power transistor Q. Since no voltage is induced, the output voltages of the switching power supply circuits SMPS are all 0V.

That is, the power consumption of the monitor is reduced to 1W or less by blocking the generation of the power supply voltage of the switching power supply circuit SMPS in the off mode using the soft start circuit built in the power supply control means 10.

Accordingly, the PC integrated monitor satisfies the VESA specification because it consumes about 4W of power in the PC itself and less than 1W of power in the monitor itself in the off mode.

As described above, the circuit according to the present invention does not generate all the power supply voltages required for each display device in the OFF mode, so that the power consumption of the display device is reduced. .

Claims (4)

Charging means for charging a predetermined voltage; In the initial operation, a PWM control signal is generated by the charging voltage of the charging means to control the warm-up voltage to be supplied to each circuit, and after the initial operation, the PWM control signal is generated by the feedback voltage to supply the rated voltage to each circuit. Power control means for controlling and stopping generation of the PWM control signal when the charging means is discharged; A microcomputer which outputs an off signal in the off mode; And a power saving means for discharging said charging means when an off signal is input from said microcomputer. The power saving means of claim 1 And a switching means for switching on by the off signal and discharging the charging means. The method of claim 2 wherein the switching means The power saving circuit of the display device, characterized in that for operating by receiving the off signal via a transmission means. Charging means for charging a predetermined voltage; In the initial operation, a PWM control signal is generated by the charging voltage of the charging means to control the warm-up voltage to be supplied to each circuit, and after the initial operation, the PWM control signal is generated by the feedback voltage to supply the rated voltage to each circuit. Power control means for controlling and stopping generation of the PWM control signal when the charging means is discharged; A microcomputer which outputs an off signal in the off mode; And a power saving means for discharging said charging means when an off signal is input from said microcomputer.