KR19980059114U - Monitor Screen Saver - Google Patents

Abstract

The present invention relates to a screen protection device of a monitor, the device of the present invention, by supplying a predetermined negative voltage to the control grid (G1) of the water pipe to control the amount of electrons emitted from the cathode to the fluorescent film A monitor adapted to control the brightness of a screen, comprising: a microcomputer 10 for outputting a mute signal of a first level in normal operation and a mute signal of a second level that is inverse to the first level in mode switching; A charging unit 20 charging a predetermined voltage to the capacitor C by the mute signal of the first level; And a discharge part 30 for discharging the voltage charged in the capacitor C by the mute signal of the second level to supply the discharged negative voltage to the control grid G1 of the water pipe. When the mode is changed, the negative voltage supplied to the control grid G1 of the water pipe is boosted to suppress the amount of electrons emitted from the cathode to be extremely effective. have.

Description

Monitor screen protector

The present invention relates to a screen protector of a monitor, and more particularly, to a screen protector of a monitor which is configured to remove an afterimage appearing on a screen when a mode is switched.

In general, a multi-mode monitor reproduces a video image in accordance with a signal received from a video card in a computer, which requires adjustment of each part of the circuit according to a timing parameter of the received signal.

Here, look at the classification of the monitor according to the video mode through Table 1.

TABLE 1

Classification by video mode

As shown in Table 1, horizontal and vertical frequencies differ according to the modes supported by the video card, and in particular, a video card supporting various modes, for example, a video card supporting VGA and SVGA and high resolution only modes, is mounted on the monitor. If so, the range of the horizontal frequency of each mode is about 30 to 75 KHz.

That is, when the mode is changed in the multi-mode monitor, there are parts that need to be changed in the internal circuits of the monitor. For example, the size and position of the image, the horizontal and vertical synchronization, the optimization of the deflection unit, and the various deflection correction circuits Readjustment should be done.

In particular, when a mode is changed, an afterimage and the like appear on the monitor screen. The afterimage has a problem in that the user is visually uncomfortable.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a screen protection device of a monitor that is to remove the afterimage appearing on the monitor screen when the mode is changed.

The screen protection device of the monitor according to the present invention for achieving the above object, by supplying a predetermined negative voltage to the control grid of the water pipe to control the brightness of the water pipe screen by controlling the amount of electrons emitted from the cathode to the fluorescent film 1. A monitor configured to perform: a micom for outputting a mute signal of a first level in normal operation and a mute signal of a second level that is inverse to the first level in mode conversion; A charging unit which charges a capacitor with a predetermined voltage by the mute signal of the first level; And a discharge unit for discharging the voltage charged in the capacitor by the mute signal of the second level and supplying the discharged negative voltage to the control grid of the water pipe.

That is, according to the present invention, the capacitor is charged with a predetermined voltage by a mute signal of the first level output from the micom in normal operation, and the mute signal of the second level is output from the micom when the mode is changed. By discharging the charged voltage to boost the negative voltage supplied to the control grid of the water pipe during mode switching, the amount of electrons emitted from the cathode is extremely suppressed to remove afterimages appearing on the screen during mode switching.

1 is a circuit diagram illustrating a screen protection device of a monitor according to the present invention.

* Names of symbols for main parts of the drawings

10: microcomputer 20: charging unit

30: discharge part G1: control grid of the water pipe

C: Capacitor D: Diode

R 1,2,3,4,5,6,7,8,9,10: resistance Q 1,2,3,4,5: 1,2,3,4,5 transistor

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

1 is a circuit diagram illustrating a screen protection device of a monitor according to the present invention.

Device according to the present invention, as shown in Figure 1, the microcomputer 10; A charging unit 20; And a discharge unit 30.

Here, the charging unit 20 has a first transistor Q1 through which a base terminal receives a mute signal of a first level from the micom 10 through a resistor R1 and an emitter terminal receives a predetermined voltage Vcc1. Wow ; A second transistor Q2 having a base terminal connected to the collector terminal of the first transistor Q1 through resistors R3 and R4 and having an emitter terminal grounded; A third transistor Q3 having a base terminal connected to the collector terminal of the second transistor Q2 and the emitter terminal receiving a predetermined voltage Vcc2 through a resistor R5; And one end thereof is connected to the collector end of the third transistor Q3 through the diode D, and the other end thereof is grounded through the first resistor R6 and in parallel with the first resistor R6. It consists of a capacitor (C) connected to the control grid (G1) of the water pipe.

Here, the discharge unit 30 includes: a fourth transistor Q4 whose base end receives a second level mute signal from the microcomputer 10 through the resistors R7 and R8, and the emitter end is grounded; The base terminal is connected to the collector terminal of the fourth transistor Q4 through the resistor R9, and the emitter terminal is connected in parallel between the collector terminal of the third transistor Q3 and the capacitor C through the resistor R10. And the fifth transistor Q5 having the collector terminal grounded.

Then look at the operation and effects of the present invention configured as described above in detail.

In general, supplying the necessary voltage (rated voltage) to each monitor circuit at the time of power on / off or mode switching of the monitor causes an abnormality in each monitor circuit. After the circuit warms up, it is necessary to supply a ready voltage lower than the rated voltage so that it can operate normally, and then supply the rated voltage. This is called a mute function, and a mute signal for performing the mute function is output from the micom 10.

The mute signal maintains a low level during normal operation, and then transitions to a high level for a while during power on / off or mode switching.

The apparatus according to the present invention is divided into normal operation and mode conversion as follows.

1. In normal operation

Since the mute signal of the first level (low level) is output from the micom 10, the low level mute signal is applied to the base terminal of the PNP type first transistor Q1, and the first transistor Q1 is applied. Is turned on.

As the first transistor Q1 is turned on, a high level signal is applied to the base terminal of the NPN-type second transistor Q2, and the second transistor Q2 is turned on.

As the second transistor Q2 is turned on, a low level signal is input to the base terminal of the PNP type third transistor Q3, and the third transistor Q3 is turned on.

Meanwhile, a low level mute signal is also applied to the base terminal of the NPN-type fourth transistor Q4 to turn off the fourth transistor Q4.

As the fourth transistor Q4 is turned off, a high level signal is applied to the base terminal of the PNP type fifth transistor Q5, thereby turning on the fifth transistor Q5.

As a result, as the third transistor Q3 is turned on and the fifth transistor Q5 is turned off, a predetermined voltage Vcc2 is applied to the emitter terminal of the third transistor Q3 to allow the capacitor C to pass through the collector terminal. ) Is charged.

2. When switching mode

Since the mute signal of the second level (high level) is output from the micom 10, the high level mute signal is applied to the base terminal of the PNP type first transistor Q1, and the first transistor Q1 is applied. Is turned off.

As the first transistor Q1 is turned off, a low level signal is applied to the base terminal of the NPN-type second transistor Q2, so that the second transistor Q2 is turned off.

As the second transistor Q2 is turned off, a high level signal is input to the base terminal of the PNP type third transistor Q3, and the third transistor Q3 is turned off.

On the other hand, a high level mute signal is also applied to the base terminal of the NPN type fourth transistor Q4, and the fourth transistor Q4 is turned on.

As the fourth transistor Q4 is turned on, a low level signal is applied to the base terminal of the PNP type fifth transistor Q5, and the fifth transistor Q5 is turned off.

As a result, as the third transistor Q3 is turned off and the fifth transistor Q5 is turned on, the voltage charged in the capacitor C is passed through the resistor R10 to the emitter of the fifth transistor Q5. Since it is applied to the terminal and discharged to the first resistor R6 through the collector terminal, (A) point voltage is supplied to the control grid G1 of the water pipe.

In this case, the (A) point voltage represents a negative voltage and the magnitude of the negative voltage may be adjusted through the resistors R10 and R6.

Therefore, by boosting the control grid G1 voltage supplied to the water pipe, the amount of electrons emitted from the cathode to the fluorescent film is extremely suppressed.

In general, in order for a screen to appear on an image tube, one spot must appear on a fluorescent film, and the spot must be deflected from side to side to make the raster and change the brightness of the spot as an image signal.

The spot is a small point of light generated when an electron beam collides with a fluorescent film of a CRT. When the monitor is turned on, the cathode (cathode) of the electron gun is sufficiently heated to emit electrons. Spots are generated by hitting the film.

This spot can be controlled by the control grid (G1) current supplied from the fly-back transformer (FBT) to the water pipe. The control grid (G1) current controls the amount of electrons emitted from the cathode of the CRT. Control the brightness modulation (brightness modulation).

At this time, the larger the negative voltage is supplied to the control grid G1, the greater the power for suppressing the electron emission of the cathode, so that the amount of electrons colliding with the fluorescent film is reduced, thereby darkening the spot.

That is, by changing the voltage of the control grid (G1) it is possible to change the brightness of the spot.

Accordingly, the device of the present invention, since the voltage of the control grid (G1) directly affects the water pipe, it is possible to eliminate the afterimage appearing on the screen of the water pipe when the mode is changed.

As described above, according to the present invention, a predetermined voltage is charged to the capacitor C by a mute signal of the first level output from the micom 10 in a normal operation, and then the microcom 10 is changed from a mode change. By discharging the voltage charged in the capacitor (C) by the output mute signal of the second level, by boosting the negative voltage supplied to the negative voltage to the control grid (G1) of the water pipe, The effect is to remove the afterimages appearing on the screen during mode conversion by suppressing the amount of electrons emitted from the cathode to the maximum.

Claims (3)

In a monitor adapted to control the brightness of a picture tube screen by supplying a predetermined negative voltage to the control grid (G1) of the picture tube and controlling the amount of electrons emitted from the cathode to the fluorescent film, A microcomputer 10 for outputting a mute signal of a first level in normal operation and a mute signal of a second level that is inverse to the first level in mode conversion; A charging unit 20 charging a predetermined voltage to the capacitor C by the mute signal of the first level; And And a discharge part 30 which discharges the voltage charged in the capacitor C by the mute signal of the second level and supplies the discharged negative voltage to the control grid G1 of the water pipe. The screen protector of the monitor characterized in that there is. The method of claim 1, wherein the charging unit 20, A first transistor Q1 through which a base terminal receives a mute signal of a first level from the microcomputer 10 through a resistor R1 and an emitter terminal receives a predetermined voltage Vcc1; A second transistor Q2 having a base terminal connected to the collector terminal of the first transistor Q1 through resistors R3 and R4 and having an emitter terminal grounded; A third transistor Q3 having a base terminal connected to the collector terminal of the second transistor Q2 and the emitter terminal receiving a predetermined voltage Vcc2 through a resistor R5; And One end is connected to the collector end of the third transistor Q3 through the diode D, and the other end is grounded through the first resistor R6 and in parallel with the first resistor R6. A screen protection device for a monitor, characterized by comprising a capacitor (C) connected to the control grid (G1) of the water pipe. The discharge unit 30 of claim 2, A fourth transistor Q4 whose base end receives a second level mute signal from the microcomputer 10 through resistors R7 and R8 and whose emitter end is grounded; The base terminal is connected to the collector terminal of the fourth transistor Q4 through the resistor R9, and the emitter terminal is connected in parallel between the collector terminal of the third transistor Q3 and the capacitor C through the resistor R10. And a fifth transistor (Q5) whose collector end is grounded.