KR19990003615U - Vertical Size Compensation Circuit of Monitor - Google Patents

Abstract

The present invention is connected to the secondary coil of the flyback transformer (30) for supplying the anode voltage to the water pipe is connected to the secondary coil of the automatic luminance limiting circuit to limit the anode current that changes as the brightness of the screen does not flow above or below a predetermined value ( 41 outputs a signal for controlling the brightness of the screen, and the signal output from the auto luminance limiting circuit section 41 is input to the vertical deflection circuit section 50 for outputting a sawtooth wave signal for vertically deflecting the video signal. The vertical deflection circuit section 50 outputs a sawtooth wave signal whose magnitude is increased in proportion to the magnitude of the input signal output from the automatic luminance limiting circuit section 41 to adjust the vertical size of the screen. It relates to a vertical size compensation circuit. This circuit is configured to control the brightness of the screen by outputting a signal having a lower voltage as the auto luminance limiting circuit section 41 becomes brighter. When the signal having a low voltage is output from the auto luminance limiting circuit section 41, the vertical deflection is performed. When the circuit unit 50 outputs a sawtooth wave signal for reducing the vertical size of the screen, and a signal having a high voltage is output from the automatic luminance limiting circuit unit 41, the vertical deflection circuit unit 50 generates a sawtooth wave signal for increasing the vertical size of the screen. Since it is output, the vertical size is automatically corrected and does not change even if the brightness of the screen changes.

Description

A circuit for compensating a V.size of a monitor

The present invention relates to a vertical size compensation circuit of a monitor, and in particular, a monitor configured to automatically compensate for a vertical size that changes as the brightness of a screen changes by using an output signal of an automatic brightness limiting (ABL) circuit of the monitor. It relates to a vertical size compensation circuit of.

In general, in the monitor, the vertical size (V.size) of the screen is changed when the user adjusts the key input switch, and the adjustment range is predetermined to maintain the output characteristics of the screen in a stable state according to the video mode. It is limited to the reference value.

If the user adjusts the key input switch, a vertical size control signal for varying the vertical size is output from the microcomputer and applied to the vertical deflection circuit portion. When the predetermined vertical size control signal is applied to the vertical deflection circuit portion, the vertical deflection is applied. The circuit unit outputs a predetermined sawtooth signal whose waveform is large in proportion to the size of the vertical size control signal and supplies the same to the vertical deflection coil. At this time, a predetermined vertical magnetic field is induced around the vertical deflection coil, and electrons output from the cathode of the water pipe are deflected in the vertical direction of the water pipe by the vertical magnetic field.

However, if the user adjusts the contrast of the screen while the vertical size of the screen is adjusted to a predetermined value, the anode current of the water pipe changes, and if the anode current is changed, the anode voltage also changes, resulting in the vertical of the screen. Change the size. Accordingly, since the horizontal output transistor of the horizontal output stage connected to the primary coil of the flyback transformer (FBT) for supplying the anode voltage to the water pipe may be overloaded, the horizontal output transistor may be damaged. As shown, in order to prevent the size of the screen and the horizontal output transistor from being damaged by the anode current of the water pipe flowing above or below a predetermined value, the anode current of the water pipe is restricted from flowing above or below a predetermined value. The automatic luminance limiting circuit section 40 is provided, and the operation of restricting the anode current of the water pipe by the automatic luminance limiting circuit section 40 from flowing above a predetermined value will be described as follows.

When the user increases the contrast by adjusting the key input switch to brighten the screen, a predetermined contrast control signal is output from the microcomputer 10 to amplify the RGB image signal and supply the amplified RGB image signal to the cathode of the receiving tube. It is input to the contrast terminal of the amplifier 20. Accordingly, the video amplifier 20 outputs a predetermined RGB video signal whose brightness is adjusted in proportion to the magnitude of the contrast control signal. At this time, when the anode current of the water pipe increases as the screen becomes brighter than a predetermined value, the anode voltage decreases, so that the automatic luminance control circuit unit 40 is a secondary coil of the flyback transformer 30. It will flow current.

Therefore, as shown in FIG. 1, part of the contrast control signal output from the microcomputer 10 and input to the video amplifier 20 flows to the auto luminance limiting circuit unit 40, so that the video amplifier 20 is actually used. ), The magnitude of the contrast control signal inputted to) becomes smaller than the contrast control signal initially output from the microcomputer 10. That is, the screen is not brightened above a predetermined value and the anode current does not increase above a predetermined value, thereby preventing the horizontal output transistor from being damaged.

However, even if the automatic luminance limiting circuit unit 40 limits the anode current to prevent breakage of the horizontal output transistor, the vertical size of the screen changes when the size of the contrast control signal input to the video amplifier 20 changes. Therefore, there is a problem in that the screen size is not accurately adjusted to the size of the vertical size that the user initially adjusted.

In order to solve the above problems, the present invention provides a vertical size compensation circuit of a monitor configured to automatically compensate for a vertical size that changes as the brightness of the screen changes by using an output signal of the automatic luminance limiting circuit unit. The purpose is.

In order to achieve the above object, the present invention is connected to the secondary coil of the flyback transformer for supplying the anode voltage to the water pipe to limit the anode current that changes as the brightness of the screen changes above or below a predetermined value. The automatic luminance limiting circuit section outputs a predetermined signal for controlling the brightness of the screen, and the signal output from the automatic luminance limiting circuit section outputs a predetermined sawtooth wave signal for vertically deflecting the video signal. The vertical deflection circuit unit outputs a predetermined sawtooth signal whose magnitude increases in proportion to the magnitude of the input signal outputted from the automatic luminance limiting circuit unit to adjust the vertical size of the screen.

The apparatus of the present invention as described above is to control the brightness of the screen by outputting a signal with a lower voltage as the screen brightness is brighter, the signal with a lower voltage from the auto brightness circuitry as the screen is brighter Is outputted, the vertical deflection circuit unit outputs a predetermined sawtooth signal for reducing the vertical size of the screen. On the contrary, when the screen is dark, when the signal having a high voltage is output from the auto luminance limiting circuit unit, the vertical deflection circuit unit A predetermined sawtooth signal for increasing the vertical size is output.

1 is a diagram showing a circuit for controlling the contrast of a screen by an automatic luminance limiting circuit section;

FIG. 2 is a diagram illustrating a circuit for compensating the vertical size of a screen by using an output signal of an auto luminance limiting circuit unit according to the present invention.

* Description of the symbols for the main parts of the drawings *

10: micom 20: video amplifier

30: flyback transformer 40, 41: auto luminance limit circuit

50: vertical deflection circuit portion D1: diode

C1: capacitor R1, R2, R3, R4, R5, R6, R7: resistor

Q1: transistor

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

FIG. 2 is a diagram illustrating a circuit for compensating the vertical size of a screen by using an output signal of an auto luminance limiting circuit unit according to the present invention.

As shown in FIG. 2, an embodiment according to the present invention includes a flyback transformer 30 for supplying an anode voltage to a water pipe; An automatic luminance limiting circuit unit 41 configured to control a brightness of the screen by outputting a signal having a lower voltage as the screen becomes brighter and limiting the anode current from flowing above or below a predetermined value; And a vertical deflection circuit section 50 for outputting a predetermined sawtooth wave signal for vertical deflection of the video signal.

Referring to the operation of the embodiment according to the present invention configured as described above are as follows.

First, as the screen becomes brighter, the anode current increases, and accordingly, when the anode voltage decreases and the vertical size of the screen increases, as illustrated in FIG. 2, the resistor R1 and the capacitor C1 in the automatic luminance limiting circuit section 41 are shown. Through this, the current i1 flowing to the secondary coil of the flyback transformer 30 is increased. At this time, since the automatic luminance limit voltage appearing at the branch A of the voltage distribution resistor R2 and the resistor R1 is reduced, the current applied to the base of the transistor Q1 is reduced through the diode D1 and the resistor R3, so that the resistor R5 and the collector of the transistor Q1 and The current i2 flowing through the emitter will also decrease. Therefore, since the voltage applied to the output terminal between the emitter of the transistor Q1 and the resistor R6 is lowered, the voltage of the output signal input to the vertical deflection circuit unit 50 through the resistor R7 is lowered. As such, when a signal having a low voltage is input to the vertical deflection circuit unit 50, the vertical deflection circuit unit 50 outputs a predetermined sawtooth wave signal for reducing the vertical size of the screen, which is increased as the brightness is adjusted, thereby increasing the vertical size. Compensates for the size initially adjusted by the user.

Here, the power supply voltage + 80V supplied through the resistor R1 and the power supply voltage + 12V supplied through the resistor R5 and the resistor R4 are power supply voltages for limiting the magnitude of the output signal of the auto luminance limiting circuit unit 41. That is, the magnitude of the voltage represented by the current i1 flowing into the flyback transformer 30 is equal to or less than +80 V, and the voltage of the signal output to the output terminal of the transistor Q1 is equal to or less than +12 V.

On the contrary, when the screen becomes dark, the anode current decreases, and accordingly, when the anode voltage increases and the vertical size of the screen decreases, the current flows to the secondary coil of the flyback transformer 30 through the resistor R1 and the capacitor C1. The current i1 decreases, and the auto luminance limit voltage appearing at the branch point A of the voltage distribution resistor R2 and the resistor R1 increases. Therefore, the current applied to the base of the transistor Q1 increases through the diode D1 and the resistor R3, so that the current i2 flowing through the resistor R5 and the collector and emitter of the transistor Q1 also increases, and the emitter and The voltage applied to the output terminal between the resistors R6 becomes high. In this case, since the voltage of the output signal inputted to the vertical deflection circuit part 50 through the resistor R7 becomes high, the vertical deflection circuit part 50 is a predetermined sawtooth signal for increasing the vertical size of the screen, which is smaller as the brightness is adjusted. To compensate for the vertical size.

As described above, according to the present invention, when the screen is brighter, the signal is lowered as the screen is brightened by outputting a signal having a lower voltage to control the brightness of the screen. The vertical deflection circuit unit outputs a predetermined sawtooth wave signal for reducing the vertical size of the screen, and conversely, when the screen is dark, when the high voltage signal is output from the auto luminance limiting circuit unit, the vertical deflection circuit unit increases the vertical size of the screen. By outputting a predetermined sawtooth signal, the vertical size is automatically corrected and does not change even if the brightness of the screen changes.

Claims (1)

An automatic luminance limiting circuit portion 41 is connected to the secondary coil of the flyback transformer 30 for supplying the anode voltage to the water pipe and restricts the anode current which changes as the brightness of the screen changes from above or below a predetermined value. Outputs a predetermined signal for controlling the brightness of the screen, and the signal output from the automatic luminance limiting circuit section 41 is input to the vertical deflection circuit section 50 for outputting a predetermined sawtooth signal for vertically deflecting the video signal. When the vertical deflection circuit unit 50 outputs a predetermined sawtooth signal whose magnitude is increased in proportion to the magnitude of the input signal output from the automatic luminance limiting circuit unit 41 to adjust the vertical size of the screen. Vertical size compensation circuit of the monitor.