KR100229511B1 - First grid muting circuit of a cathode ray tube - Google Patents

Abstract

The present invention relates to a first grid muting circuit for monitor display. The first grid muting circuit according to the present invention is a micom for providing a muting signal to the blocks for each mode to provide a more stable image to the user by smoothing the muting operation of the muting circuit portion of each block, the micom A contrast muting circuit section connected to one branch of an output terminal of the output terminal for muting the muting signal to a predetermined level, a video circuit connected to an output terminal of the contrast muting circuit section and outputting a muted video signal as a video signal, and an output terminal of the microcomputer output terminal. A first grid muting circuit, connected to the other branching point of the circuit, and comprising a first grid driver for driving the first grid circuit; The first grid driver is connected to the first grid muting controller and the first grid muting driver, and the first grid muting controller is connected to a resistor, a transistor, a muting signal, and a power source connected in parallel to a positive power supply voltage input terminal, respectively. A switch or switching transistor for switching the voltage, resistors and variable resistors for controlling the negative power supply voltage, and the first grid muting driver is composed of a zener diode, a resistor and a transistor. Therefore, such a first grid muting circuit has an advantage that it is usefully applied to the monitor circuit.

Description

First grid muting circuit

1 is a block diagram showing an embodiment of a conventional first grid muting circuit,

2 is a block diagram showing an embodiment of a first grid muting circuit according to the present invention;

3 is a detailed circuit diagram illustrating an embodiment of a first grid muting circuit according to FIG. 2;

4 is a detailed circuit diagram showing another embodiment of the first grid muting circuit according to the present invention;

5a is an operational waveform diagram according to FIG.

(b) is an operating waveform diagram according to FIG.

(c) is an operating waveform diagram according to FIG.

<Description of the code | symbol about the principal part of drawing>

10: micom 20: contrast muting circuit

30: video contrast portion 40: first grid circuit

50: first grid driver 60: first grid muting driver

70: first grid muting control unit

R2 to R7, R12 to R9, R22 to R29: resistors C11, C12, C21, C22: capacitors

ZD1, ZD11, Z21: Zener Diode VR1, VR11, VR21: Variable Resistor

Q1, Q2, Q11 to Q13, Q21 to Q23: transistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a first grid circuit for a monitor display, and more particularly to a first grid circuit embedded in a cathode ray tube (hereinafter referred to as a CRT) at mode switching or power-on of a monitor. The first grid muting circuit provides a clear image by preventing the raster from being distorted and displayed by muting.

In general, the first grid muting circuit refers to a circuit in which an amount of electrons collided with a fluorescent surface by an electron gun is arbitrarily controlled when a hot electron is emitted to impinge on a fluorescent surface with a thin electron beam. The electron gun is composed of a cylindrical cathode, a grid, and an anode, and the first grid G1 of the grid controls the amount of electrons emitted from the cathode as a suppression grid to control the brightness change or the brightness change.

FIG. 1 shows a detailed circuit diagram according to a conventional first grid muting circuit. Referring to the block concept, a microcomputer 10 providing a muting signal output through a microprocessor to blocks corresponding to a mode, and the microcomputer 10 A video muting circuit section 20 connected to one branch of the output terminal of the video output terminal for muting the muting signal to a video signal, and a video contrast section 30 for adjusting the muted video signal connected to the output terminal of the video muting circuit section 20. ) And a first grid driver 50 for driving the first grid circuit 40 connected to the other branch point of the output terminal of the microcomputer 10.

Here, the first grid driver 50 includes resistors R6 and R7 connected to an output terminal of the first grid circuit 40, a transistor Q2 connected in parallel with a collector of the resistor, and a transistor Q2. Resistors R4 and R6 connected in series to the emitter and variable resistor VR1 connected to the resistor R5, and resistors commonly connected to the other branch of the output terminal of the base and the microcomputer 10 of the transistor Q2. (R2, R3) and zener diode ZD1.

In addition, the contrast muting circuit unit 20 is connected between one side branch point of the output terminal of the microcomputer 10 and the input terminal of the video contrast unit 30, and a resistor R1 connected to the transistor Q1 and the base of the transistor Q 1. )

In the conventional first grid muting circuit configured as described above, referring to FIG. 1, first, a power supply voltage is applied to each block, and the microcomputer 10 transmits a predetermined muting signal to the contrast muting circuit unit 20 and the video muting through a branch point. It supplies to the circuit part 50.

Accordingly, the muting signal drives the transistor Q1 through the resistor R1, so the video contrast unit 30 supplies the video signal adjusted to a predetermined level to the video circuit (not shown).

In addition, the muting signal output to the microcomputer 10 is applied to the base of the transistor Q1 through the resistor R2 and the zener diode ZD1 of the first grid driver 50 connected to the other branching point, thereby transmitting the transistor Q1. Turn on. Here, the level of the muting signal appearing at the node point A is shown in FIG. 5A.

At this time, when the first grid control voltage is equal to the negative power supply voltage (-Vcc) by the resistors R4 to R7 and the variable resistor VR1 connected in parallel to the collector and the base of the transistor Q1, respectively, the resistance ( A predetermined voltage is supplied to the first grid circuit 40 through R7) to act as a signal for lowering the luminance signal of the cathode ray tube. In addition, even though the muting signal is not output from the microcomputer 10, the voltage formed by the resistors R5 and R7 and the variable resistor VR1 is supplied to the first grid circuit 40 as a reference voltage.

Therefore, the control voltage finally adjusted by the first grid circuit 40 is applied to the vertical blanking circuit.

However, in the conventional first grid muting circuit, the difference between the output level of the muting signal output from the microcomputer and the power supply voltage level supplied from the flyback transformer is negative at the negative level, resulting in unstable operation of the contrast muting circuit part. The grid circuit also cannot output the correct grid voltage, and as a result, a clean image cannot be obtained from the cathode ray tube.

Therefore, the present invention aims to secure such disadvantages, and an object of the present invention is to provide a first grid muting circuit which can provide a more stable image to a user by smoothing the muting operation of each muting circuit part of each block. have.

Features of the present invention for achieving the above object is a micom for providing a muting signal in blocks for each mode, a contrast muting circuit for connecting to one branch of the output terminal of the micom and muting the muting signal to a predetermined level; And a video circuit connected to an output terminal of the contrast muting circuit unit and outputting a muted video signal as a video signal, and a first grid driving unit connected to another branch point of the output terminal of the microcomputer and driving a first grid circuit. A first grid muting circuit; The first grid driver is connected to the first grid muting controller and the first grid muting driver, and the first grid muting controller is connected to the resistors, the transistor, the muting signal, and the power supply connected in parallel to the positive power supply voltage input terminal. It consists of a switch for switching the voltage, resistors for controlling the negative power supply voltage and a variable resistor, and the first grid muting driver consists of a zener diode, a resistor and a transistor.

Another feature of the present invention is a microcomputer for providing a muting signal to the corresponding mode-specific blocks, a contrast muting circuit unit connected to one branch of the output terminal of the microcomputer and muting the muting signal to a predetermined level, and the contrast muting circuit unit. A first circuit muting circuit comprising a video circuit connected to an output terminal and outputting a muted video signal as a video signal, and a first grid driving unit connected to the other branch point of the output terminal of the microcomputer and driving a first grid circuit. In; The first grid driver is connected to the first grid muting controller and the first grid muting driver, and the first grid muting controller is connected to the positive power voltage input terminal in parallel with resistors, transistors, muting signals, and power supplies. The first grid muting driver is composed of a zener diode, a resistor and a transistor, and the other transistor for switching the voltage, resistors and variable resistors for controlling the negative power supply voltage.

Hereinafter, an embodiment of a first grid muting circuit according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of an embodiment of a first grid muting circuit according to the present invention, and includes a micom 10 for providing a muting signal to blocks corresponding to a mode, and one side branch point of an output terminal of the micom 10. A contrast muting circuit section 20 for connecting the muting signal to a predetermined level and a video circuit 60 connected to an output terminal of the contrast muting circuit section 20 for outputting the muted video signal as a video signal; A first grid muting driver 70 for driving the first grid circuit 40, the first grid muting driver 70, and the microcomputer 10 connected to the other branching point of the output terminal of the microcomputer 10. And a first grid muting controller 80 for common driving between the other output terminals of the first grid muting driver 70 and selectively driving the first grid muting driver 70.

Here, referring to the detailed circuit diagram of FIG. 3, in the first grid muting control unit 80, resistors R13 and R14 and a capacitor C1 are connected in parallel to a positive power supply voltage input terminal (+ Vcc), and the resistor ( The collector of the transistor Q12 is connected to R13, a capacitor C1 and a switching switch SW are connected to the collector, and another resistor R12 is connected to the base, and a negative power supply voltage input terminal (-Vcc) is connected to the collector. The resistors R16 and R19 and the variable resistor VR1 are connected in parallel between one grid circuit input terminal.

In addition, the first grid muting driver 80 has a transistor Q13 connected in parallel to the resistors R17 and R9 of the first grid muting control unit 80, and is common between the base and the emitter of the transistor Q13. Zener diode ZD1 is commonly connected between the connected resistor R15 and the base of the transistor Q13 and the switching switch SW of the first grid muting driver 80.

Thus, referring to the detailed circuit diagram of FIG. 3 and the waveform diagram of FIG. 5, when the mute signal is generated in the microcomputer 10, a constant potential is applied to the base through the resistors R11 and R12, and thus the transistors Q11 and Q12. ) Is turned on. At this time, the transistor Q11 applies the muting signal contrasted to the video circuit 60 by contrast muting the mute signal, and as the transistor Q12 of the first grid muting control unit 80 is turned on, the resistor R13 and The switch SW is released by the capacitor C11.

In addition, a positive power supply voltage (+ Vcc) drives the transistor Q13 through the resistor R14, the capacitor C12, and the zener diode ZD11 by connecting the switch SW, and the resistors R16, R18 and The first grid control voltage formed by the variable resistor VR1 is cut off by the resistor R17 so that only the first grid muting is performed in the first grid circuit 40. At this time, it should be noted that the waveform as shown in FIG. 5B appears at the node point (B).

On the other hand, when the muting is released, the transistors Q11 and Q12 are turned off. In this case, the switch SW is switched on and the transistor Q13 is also turned off without affecting the video contrast muting circuit unit 20.

Therefore, since the first grid voltage (see FIG. 5c) formed by the resistors R16 and R18 and the variable resistor VR1 is applied to the first grid circuit 40 through the resistors R17 and R19, the luminance signal level is controlled. Done.

As described above, in the present invention, the image quality deterioration caused by simultaneously performing the first grid muting and the luminance signal level can be obtained by separating the first grid muting and the luminance signal level separately.

4 shows another embodiment of the first grid muting circuit according to the present invention, and has the same block configuration as that of FIG. 3 except that the first grid muting control unit 80 controls the first grid muting and luminance signals. The switch SW for controlling the level is replaced by the switching transistor 24.

Detailed configuration description thereof will be omitted, and referring to the detailed circuit diagram shown in FIG. 4 and the waveform diagram of FIG. 5, when a mute signal is generated in the microcomputer 10, a constant potential is applied to the base through the resistors R21 and R22. Is applied, the transistors Q21 and Q22 are turned on. At this time, the transistor Q21 contrast mutes the mute signal to apply the contrast muting signal to the video circuit 60, and the resistors R23 and R31 as the transistor Q22 of the first grid muting control unit 80 is turned on. And the capacitor C21 turn off the switching transistor Q24.

In addition, a positive power supply voltage (+ Vcc) drives the transistor Q23 through the resistor R24, the capacitor C22, and the zener diode ZD21 by turning off the switching transistor Q24, and the resistors R26, The first grid control voltage formed by R28) and the variable resistor VR2 is cut off by the resistor R27 so that only the first grid muting is performed in the first grid circuit 40.

At this time, it should be noted that the waveform as shown in FIG. 5B appears at the node point (B).

On the other hand, when the muting is released, the transistors Q21 and Q22 are turned off. In this case, the transistor Q23 is turned off by turning on the switching transistor Q24 without affecting the video contrast muting circuit unit 20.

Therefore, the first grid voltage (see also 5c) formed by the resistors R26 and R28 and the variable resistor VR2 is applied to the first grid circuit 40 through the resistors R27 and R29, thereby controlling the luminance signal level. Done.

Such a first grid muting circuit can control the grid control voltage and muting operation applied to the first grid circuit by using a switching transistor rather than switching using a switch means as shown in FIG. .

As described above, the present invention provides a clear image to the user by eliminating raster distortion generated during power on or mode conversion by muting the first grid more smoothly so as to accurately perform operations on power on or mode conversion. In addition, it is possible to reduce the cost by using a small transistor in the configuration of the device for the first grid control.

Claims (2)

A microcomputer for providing muting signals to corresponding mode-specific blocks, a contrast muting circuit unit connected to one branch of the output terminal of the micom and muting the muting signal to a predetermined level, and connected and muted to an output terminal of the contrast muting circuit unit. A first grid muting circuit comprising a video circuit for outputting a video signal as a video signal, and a first grid driver connected to the other branch point of the output terminal of the microcomputer, and for driving a first grid circuit; The first grid driver is connected to the first grid muting controller and the first grid muting driver, and the first grid muting controller includes resistors, a transistor, a muting signal, and a power source connected in parallel to a positive power voltage input terminal, respectively. And a switch for switching a voltage, resistors for controlling a negative power supply voltage, and a variable resistor, wherein the first grid muting driver comprises a zener diode, a resistor, and a transistor. A microcomputer for providing muting signals to corresponding mode-specific blocks, a contrast muting circuit unit connected to one branch of the output terminal of the micom and muting the muting signal to a predetermined level, and connected and muted to an output terminal of the contrast muting circuit unit. A first grid muting circuit comprising a video circuit for outputting a video signal as a video signal, and a first grid driver connected to the other branch point of the output terminal of the microcomputer, and for driving a first grid circuit; The first grid driver is connected to the first grid muting controller and the first grid muting driver, and the first grid muting controller includes resistors, a transistor, a muting signal, a power source connected in parallel to a positive power voltage input terminal, respectively. A first grid muting circuit, comprising: another transistor for switching a voltage, resistors and a variable resistor for controlling a negative power supply voltage, and wherein the first grid muting driver is comprised of a zener diode, a resistor, and a transistor.