KR970006129Y1 - Circuit for correction of horizontal size - Google Patents

Abstract

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Description

Horizontal size correction circuit

1 is a horizontal size correction circuit with a conventional mute circuit.

FIG. 1 shows waveforms of respective parts in the absence of the synchronization signal of FIG. 2. FIG.

3 is a waveform diagram of each part of FIG.

4 is an operation block diagram of a horizontal size correction circuit of the present invention.

5 is a horizontal size correction circuit diagram more detailed than FIG.

6 is an operation description table of FIG.

7 is a waveform diagram of each part of FIG. 4 in the absence of a synchronization signal.

8 is a waveform diagram of each part of FIG.

9 is a comparison of the output screen after applying the correction circuit.

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

1: MUTE circuit 2: Horizontal size control circuit

3: horizontal oscillation unit 4: synchronization presence detection unit

5: smoothing part 6: voltage comparing part

7: Compensation voltage generator

In the present invention, the horizontal size of the screen is narrowly displayed when there is no vertical or horizontal synchronous signal in a general monitor, and sometimes the drive of the horizontal output part is overdriven, which causes the output transistor to be destroyed or the reliability decreases. And a horizontal size correction circuit to operate constantly.

The conventional horizontal size correction circuit includes a mute circuit 1 for detecting horizontal and vertical synchronous signals and outputting them as a control signal, as shown in FIG. 1, and a parallel circuit for rapidly transferring the signals output from the mute circuit. Horizontal oscillator (3) for adjusting the horizontal size by inputting the connected capacitor (C1) and resistor (R1), the output signal from the capacitor (C1) and resistor (R1) and the output signal of the horizontal size control circuit (2). It is composed of

Referring to the prior art operation configured as described above in detail, as shown in (a) and (b) of FIG. 2, when there is no horizontal and vertical synchronization signal, the output of the mute circuit 1 becomes high. A high voltage is generated and the output voltage overlaps with the output voltage of the horizontal size control circuit 2 to generate a compensated voltage as shown in FIG.

That is, the horizontal size control output voltage at no signal is compensated to the horizontal oscillator 3 by the output voltage of the mute circuit 1, so that the horizontal size is corrected at no signal.

On the contrary, when there are horizontal and vertical synchronization signals as shown in FIG. 3 (a) and (b), the output of the mute circuit 1 becomes low as shown in FIG. 3 (c). Only horizontal size control voltage is output.

However, in the conventional technology, the horizontal size correction is possible even when there is no signal in a monitor with a mute circuit, but in general, the horizontal size is narrowly displayed because there is no mute circuit, and the horizontal drive is sometimes overdriven, It causes destruction or deterioration of reliability.

Accordingly, an object of the present invention is to provide a horizontal size correction circuit that generates a compensation voltage regardless of whether or not there is a mute circuit and always maintains a constant horizontal size.

The purpose of the present invention is to detect the presence or absence of horizontal / vertical synchronization input as shown in FIG. 4 and to generate a horizontal compensation control signal according to the detected result, and the result obtained by the synchronization detecting means. Is achieved by a horizontal size correction circuit comprising a compensation voltage generating means for generating a horizontal compensation voltage and superimposing the horizontal size control voltage to maintain a constant horizontal size.

FIG. 5 is a horizontal size correction circuit more detailed than FIG. 4, which is a transistor Q1 and Q2 which are switching elements, and a synchronization detector 4 for generating an output waveform in accordance with the horizontal and vertical synchronization, and a first integrating circuit. A smoothing part 5 for shaping the signal waveform obtained from the synchronous detecting part 4 with a direct current by the resistor R2, the electrolytic capacitor C1, and the resistor R3 and the electrolytic capacitor C2 as the second integrating circuit; The voltage comparison unit 6 which compares the signal voltage obtained from the smoothing unit 5 to the negative terminal of the IC by the resistors R4 and R6 is connected to the positive terminal to determine the compensation voltage, and the voltage ratio. The voltage outputted by connecting the control voltage obtained at the grant 6 to the base of the transistor Q3 as the switching element is horizontal by a diode D1 which prevents the reverse flow of the next signal set by the resistors R8 and R9. A compensation voltage generator 7 for generating a size compensation voltage; The output of the output horizontal size control circuit 2 of the groups compensation voltage generating section 7 has a configuration in which the input to the horizontal oscillation unit (3).

When described in detail with reference to Figures 5 to 8 of the operation, effects of the present invention configured as described above.

First, in the absence of the synchronization signal, in FIG. 5, since the synchronization detection unit 4 does not apply the synchronization signal to the bases of the transistors Q1 and Q2, which are switching elements, the transistors Q1 and Q2 are turned off. It becomes a state.

Therefore, referring to the operation of FIG. 6 and the table and FIG. 7 (a), if the input waveform is low, the output waveform becomes high and becomes a high output waveform as shown in FIG.

The smoothing unit 5 shapes the high output waveform of the synchronization presence detecting unit 4 and outputs the high output like the point B voltage shown in FIG.

Since the voltage comparator 6 obtains the signal voltage obtained from the smoothing unit higher than the point C voltage of FIG. 7 (D) which is the reference voltage, the operation of the comparison IC is turned on and outputs low as shown in FIG. 7 (E). do.

In the compensation voltage generator 7, a low is input from the voltage comparator to the base of the transistor Q3 so that the transistor Q3 is turned on and the output waveform is output high as shown in FIG. 7 (bar).

This output is set to an appropriate compensation voltage by resistors R8, R9 and diode D1 and then overlaps with the output of the horizontal size control circuit 2 to greatly adjust the horizontal size at no signal.

At this time, the compensated voltage is applied to the input of the horizontal oscillator 3 as shown in FIG.

Secondly, when there is a synchronization signal, pulse waveforms are input to the bases of the transistors Q1 and Q2 of the synchronization detection unit 4 as shown in FIG. 6 and FIG. 8 (a) and (b). The pulse wave is output as shown in (c).

This waveform is converted to direct current through the first and second integrating circuits of the smoothing part 5 to become a direct current signal voltage as shown in the point B voltage of FIG. 8 (D), while the reference voltage is C of FIG. 8 (D). Since the reference voltage is output like the point voltage, and the signal voltage (point B voltage) is lower than the reference voltage (point C voltage), the comparison IC is turned off and outputs high as shown in FIG.

Therefore, since the compensation voltage generator 7 is applied to the base of the transistor Q3, the transistor Q3 is turned off and outputs low to the emitter as shown in FIG. 8 (bar). ) Only the output voltage is input to the horizontal oscillator 3 as shown in FIG.

As described above, the present invention generates a compensation voltage capable of correcting the horizontal size as shown in FIG. 9 even when there is no mute circuit, and increases the horizontal size by integrating the horizontal stage of a general monitor, especially a high voltage deflection integrated type. This is useful circuit for horizontal stage of multi sync monitor.

Claims (3)

Detecting the presence / absence of horizontal / vertical synchronization and generating a horizontal compensation control signal in accordance with the detected result to obtain synchronization detection means; And a compensation voltage generating means for generating a horizontal compensation voltage according to the result obtained by the synchronization detecting means and superimposing the horizontal compensation voltage to maintain a constant horizontal size. The method of claim 1, The synchronization detecting means includes a sink presence detecting means for generating a control voltage by switching according to the presence or absence of the horizontal and vertical sync inputs; Smoothing means for shaping the control voltage obtained by the sink presence detecting means to a DC voltage of a predetermined level; And a voltage comparing means for comparing the DC voltage of the predetermined level obtained from the smoothing means with the set reference voltage and switching the resultant voltage to the resultant voltage. The method of claim 1, The compensation voltage generating means includes a switching element for switching the power supply voltage in accordance with the resultant voltage obtained by the synchronization detecting means; One or more resistors that divide the voltage resulting from the switching, A horizontal size correction circuit, comprising: a signal backflow prevention element for preventing signal backflow from a horizontal size control voltage;