KR0138680B1 - Brightness mute circuit of a monitor - Google Patents

Abstract

The present invention relates to a brightness mute circuit of a monitor to mute the brightness when the mode is changed to remove a glare or a distorted picture, the microcomputer 10 for outputting a square wave brightness signal, and the micom 10 A low pass filter 20 for filtering the output of the inverse, an inverting amplifier 30 for amplifying and inverting the input signal filtered through the low pass filter 20 to a predetermined level, and a pulse of the flyback transformer 50. Negative rectification and smoothing of the high-voltage rectifier 60 for outputting the negative voltage, the voltage variable unit 70 for varying the output of the high-voltage rectifier 60 to output to the grid terminal (G1) of the Cititi, and the voltage In the brightness control circuit of the monitor provided with the current flow control part 40 which changes the grid terminal voltage G1 by controlling the flow of electric current by the negative high voltage through the variable part 70, e. A mode detector 80 connected to an output terminal of the ECOM 10 to detect a mode by switching on / off according to a mode change state, and a zener diode turned on / off according to an output voltage level of the mode detector 80 ( ZD1 and the switching unit 90 which is switched on when the zener diode ZD1 is turned on so that the instantaneous negative voltage of the voltage variable unit 70 is applied to the grid terminal G1, and the switching unit ( It is further provided with a protection circuit 100 which is connected between the 90 and the voltage variable unit 70 to protect the switching unit 90 by distributing the voltage.

Description

Monitor brightness mute circuit

1 is a brightness adjustment circuit diagram of a conventional monitor.

2 is a brightness mute circuit diagram of a monitor according to the present invention.

* Explanation of symbols for main parts of the drawings

10: microcomputer 20: low pass filter

30: inverting amplifier 40: current flow control

50: flyback transformer 60: high pressure rectifier

70: voltage variable unit 80: mode detection unit

90: switching unit 100: protection circuit

Q1-Q4: Transistor R1-R24: Resistor

VR1: Variable resistor C1-C5: Capacitor

D1: Diode ZD1: Zener Diode

OP: op amp

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor, and more particularly, to a brightness mute circuit of a monitor that can mute the brightness when a mode is changed to remove a glare or a cial distortion screen.

In the brightness mute circuit of a conventional monitor, as shown in FIG. 1, a microcomputer 1 for outputting a brightness control signal of a square wave and a resistor for filtering only a signal of a predetermined band among the control signals of the microcomputer 1 pass ( A low-pass filter (2) consisting of R1-R4) and capacitors (C1) and (C2), an op amp (OP) that amplifies and inverts the input signal filtered through the low-pass filter (2) to a predetermined level, and a resistor. Negative rectification and smoothing of the pulses of the flyback transformer 5 and the inverted amplifier 3 of (R5-R10) and a resistor (R16) and diode (D1) for outputting about -80V to the grid terminal (G1). And a high voltage rectifier 6 made of a capacitor C3 and a variable resistor VR1 and a resistor R14 and R15 for varying the output of the high voltage rectifier 6 and outputting the output to the grid terminal G1 of CALTI. The voltage variable part 7 and the inverted amplifier 3 and the voltage variable part 7 to be connected to the voltage variable part 7 at -80V. The current flow controlled by the pressure is thereby composed of transistors (Q1), the resistance (R11-R13) as the current flow controller (4) for changing the terminal grid (G1) voltage.

In the brightness adjustment circuit of the conventional monitor configured as described above, the pulse of the flyback transformer 5 passes through the diode D1 of the high voltage rectifying unit 60 and passes only the (-) component pulse (-80V). In this case, the brightness of the screen may be adjusted by controlling the emitter current of the transistor Q1 of the current flow controller 4 to adjust the bias of the grid terminal G1 of the STI.

That is, the pulse output from the microcomputer 1 is filtered while passing through the low pass filter 2, and then amplified to a predetermined level through the inversion amplifier 3 and inverted.

The inverted signal is input to the base of the transistor Q1 of the current flow controller 4 through the resistor R9. If the base potential of the transistor Q1 is lowered, the emitter current of the transistor Q1 is increased and eventually, The brightness of the screen is increased by increasing the voltage of the grid terminal G1, and when the base potential of the transistor Q1 is increased, the emitter current of the transistor Q1 is decreased, thereby lowering the voltage of the grid terminal G1, thereby decreasing the brightness of the screen. Is reduced.

Therefore, conventionally, by increasing or decreasing the emitter current of the transistor Q1, the brightness of the screen may be adjusted by controlling the grid terminal G1 voltage of the CALTI.

However, in the brightness adjustment circuit of the conventional monitor as described above, there is a problem that a flash or temporary distortion occurs during the mode conversion or the screen conversion by various screens of the vertical / horizontal frequency output from the video card. there was.

The present invention is to solve the problems of the conventional monitor, and an object of the present invention is to provide a brightness mute circuit of the monitor that can remove the momentary flash or distorted screen of the screen when the monitor mode is switched.

To achieve the above object, the present invention provides a microcomputer for outputting a brightness control signal of a square wave, a low pass filter for filtering the output of the micom, and an input signal filtered through the low pass filter to be amplified to a predetermined level and inverted. An inverting amplifying unit configured to perform a negative rectification and smoothing of the pulse of the flyback transformer, a high voltage rectifying unit for outputting about -80 V, a voltage variable unit for varying the output of the high voltage rectifying unit and outputting it to a grid terminal of the CALTI; A brightness control circuit of a monitor comprising a current flow controller connected between an amplifying unit and a voltage variable unit to control the flow of current by a high voltage of -80V through the voltage variable unit to convert the grid terminal voltage, wherein the monitor is connected to the output terminal of the microcomputer. And a mode detecting unit which detects a mode by switching on / off according to a mode change. A Zener diode which is turned on when the output voltage of the mode detector is above a predetermined level, a switching unit which is switched on when the Zener diode is turned on, and a negative voltage is applied to the grid terminal, and the switching unit and the voltage varying unit It is characterized in that it further comprises a protection circuit for connecting between and protect the transistor.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the brightness mute circuit of the monitor of the present invention will be described in detail.

2 is a circuit diagram of the present invention, which includes a microcomputer 10 for outputting a square wave brightness control signal, a capacitor C1 (C2), and a resistor R1 (R4) for filtering the output of the microcomputer 10. Inverted amplification by op amp (OP), resistors (R5-R10), and capacitor (C4) for amplifying and inverting the input signal filtered through the low pass filter 20 and the low pass filter 20 to a predetermined level. And a high-voltage rectifier 60 comprising a resistor R16, a diode D1, and a capacitor C3 that negatively rectify and smooth the pulse of the flyback transformer 50 to output about -80V. The output of the high voltage rectifier 60 is connected to the output terminal of the microcomputer 10 and the voltage variable part 70 formed of a resistor R14 and a variable resistor VR1 for varying the output of the high voltage rectifying unit 60 to the grid terminal G1 of the CT. And a mode detecting unit 80 comprising transistors Q2 and Q3 and resistors R17 and R19 that detect the mode by switching on and off according to the mode change. Zener diode ZD1 that is turned on when the output voltage of detector 80 is above a certain level, and transistor Q4 that is switched on when Zener diode ZD1 is turned on to apply a negative voltage to grid terminal G1. And a protection circuit 100 made of a resistor R21-R24 connected between the switching unit 90 and the variable voltage unit 70 to protect the transistor. And a transistor Q1 connected between the inverting amplifier 30 and the protection circuit 100 to change the grid terminal voltage by controlling the flow of current by a high voltage of -80 V through the voltage varying unit 70. ) And a current flow control unit 40 composed of resistors R11 to R13.

In the present invention configured as described above, the emitter current of the transistor Q1 of the current flow controller 40 is controlled by adjusting the variable resistor VR1 of the voltage variable part 70 and thus applied to the grid terminal G1 of CALTI. The brightness of the screen can be adjusted by varying the voltage.

That is, since the low level signal is output from the output terminal of the microcomputer 10 and the transistor Q2 of the mode detector 80 is switched off, the high level of the power supply VCC2 is applied to the base of the transistor Q3. Transistor Q3 is switched on.

Therefore, when the transistor Q3 is switched on, the zener diode ZD1 is turned off and the transistor Q4 of the switching unit 90 is turned off. The grid terminal G1 voltage of is adjusted.

However, when the mode is switched, a high level signal is output from the output terminal of the microcomputer 10, and the transistor Q2 of the mode detector 80 is switched on.

When the transistor Q2 is turned on in this way, the transistor Q2 is turned off because the base of the transistor Q2 is at the low level of the ground side, and thus the voltage of the power supply VCC2 is switched through the zener diode ZD1. Applied to the base of transistor Q4 of 90, transistor Q4 is switched on.

When the transistor Q3 is switched on as described above, the mode change is performed by dropping the grid terminal G1 voltage at the instant when the grid terminal G1 of the CALTI becomes equal to the negative voltage of the variable voltage unit 70 through the transistor Q4. This will remove the flash of light or the distortion of the screen.

As described above, the present invention has an effect of eliminating the flash or STI distortion screen by dropping the grid terminal G1 voltage of STI by outputting a predetermined level from the microcomputer 10 during mode conversion.

Claims (1)

By amplifying the input signal filtered through the microcomputer 10 for outputting the control signal of the square wave, the low pass filter 20 for filtering the output of the microcomputer 10, and the low pass filter 20 to a predetermined level Inverting amplifier 30 for inverting, high voltage rectifying unit 60 for negative rectifying and smoothing pulse of flyback transformer 50 and outputting negative pressure, and output of the high voltage rectifying unit 60 are varied The voltage variable part 70 which outputs to the grid terminal G1, and the current flow control part 40 which changes the grid terminal voltage G1 by controlling the flow of electric current by the negative high voltage through the voltage variable part 70. In the brightness control circuit of the monitor comprising a mode detecting unit 80 connected to the output terminal of the microcomputer 10 is switched on / off according to the mode change state to detect the mode, and the mode Zener diode ZD1 turned on / off according to the output voltage level of outlet 80 and switched on when zener diode ZD1 is turned on to provide instantaneous voltage excitation 70 to grid terminal G1. A switching unit 90 for applying a negative voltage and a protection circuit 100 connected between the switching unit 90 and the voltage varying unit 70 to distribute the voltage to protect the switching unit 90. The brightness mute circuit of the monitor, characterized in that configured by.