KR900006305Y1 - Horizontal and vertical synchronizing signal and field detecting circuit for video signal - Google Patents

Abstract

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Description

Horizontal vertical sync signal and field detection circuit of video signal

1 is a circuit diagram of the present invention.

2 is a waveform diagram of the present invention at the time of the second field.

3 is a waveform diagram of the present invention at the time of the first field.

* Explanation of symbols for main parts of the drawings

IC1, IC2: Monostable Multivibrator IC3, IC4: Flip-Flop

The present invention relates to a circuit for generating horizontal and vertical synchronization signals and field detection signals from video composite signals.

Image synthesized signals such as monitors and televisions have different waveforms for each field. Conventionally, as shown in Utility Model Publication No. 831 (Field Detection Circuit of Digital Television), when the first field (odd filed) starts, it is horizontal. Six pulses are generated from the equalization pulse before the sync pulse to 3H (H is the period of the horizontal sync pulse), and seven pulses are generated when the second field starts. To distinguish.

The conventional field detection circuit is not only complicated, but the field detection signal is generated by passing the horizontal synchronization signal through the integrating circuit, which causes a lot of malfunctions and frequently causes a disturbance of synchronization, and also generates a counter when the field detection signal is generated. The circuit is complicated because it generates a field detection signal.

The present invention has been made to solve the above problems, using a monostable multivibrator and a flip-flop, using a vertical synchronization signal and a horizontal synchronization using the difference between the synthesized synchronization waveforms at the first field and the second field. It is an object of the present invention to provide a circuit capable of generating a signal and a field detection signal.

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

1 shows a horizontal, vertical synchronous signal and field detection circuit diagram of an image signal of the present invention, wherein the synthesized synchronous signal A is an input terminal A1 and flip-flops IC3 and IC4 of a monostable multivibrator IC1. Input terminal (D3, D4) of the terminal), and connects the output terminal (Q1) of the monostable multivibrator (IC1) to the input terminal (B2) of the monostable multivibrator (IC2), inverted output Terminals( Outputs the detected horizontal synchronizing signal and simultaneously applies the signal to the clock terminal CK4 of the flip-flop IC4 and outputs the inverted output terminal of the monostable multivibrator IC2. ) Is connected to the clock terminal CK3 of the flip-flop IC3, and the output terminals Q3 and Q4 of the flip-flop IC3 and IC4 are connected to output the vertical synchronization signal and the field detection signal.

The monostable multivibrator IC1 or IC2 is operated when a pulse signal input to each input terminal A1 or A2 is switched from a high level to a low level or is input to each input terminal B1 or B2. It is operated when the pulse signal to be switched from the low level to the high level, and the clear terminal (CLR) and input terminal (B1) of the monostable multivibrator (IC1) and the clear terminal (1) of the monostable multivibrator (IC2). CLR) and output terminal Q2 are connected to the power supply Vcc.

Referring to the circuit operation of the present invention having the above configuration is as follows.

Equalization pulses are inserted before and after the vertical synchronizing signal of the synthetic synchronizing signal to make the vertical synchronizing signal always the same shape.When the second field starts, seven pulses are generated as shown in the waveform diagram of FIG. 2, and when the first field starts. Six pulses are generated as shown in the waveform diagram of FIG.

When a synthetic synchronous signal such as A in FIGS. 2 and 3 is input to the input terminal A1 of the monostable multivibrator IC1, the monostable multivibrator IC1 is connected to the second through the inverted output terminal Q1. And a horizontal synchronous signal as shown in FIG. Since the output (Q1) waveform of the monostable multivibrator (IC1) in which the horizontal synchronous signal is inverted is applied to the input terminal (B2) of the other monostable multivibrator (IC2), the monostable multivibrator (IC2) Waveforms such as C in FIGS. 2 and 3 are output.

Accordingly, in the flip-flop IC4, the horizontal synchronization signal is applied to the clock terminal CK4, and the synthesized synchronization signal of A of FIGS. 2 and 3 is applied to the input terminal D4, and the flip-flop IC4 is applied to the flip-flop IC4. Since the signal applied to the input terminal D4 at the rising edge of the clock signal is output directly through the output terminal, waveforms as shown in FIGS. 2 and 3 are output. That is, at the point "a" of FIG. 2 and the point "d" of FIG. 3, the low level is output through the output terminal Q4 of the flip-flop IC4, and the vertical synchronous signal of the waveforms of FIG. 2 and FIG. Will be output.

In addition, the flip-flop IC3 has an inverted output of the monostable multivibrator IC2 at the clock terminal CK3. Is applied, and a synthetic synchronous signal is applied to the input terminal D3. Since the flip-flop IC3 also operates in the same manner as the flip-flop IC4, field detection signals such as FIG. 2 and FIG. Will be output.

In this case, in the case of the field, the field detection signal should be at the low level, but the low level vertical synchronization signal which is the output signal of the flip-flop IC4 is the preset terminal of the flip-flop IC3. Since the flip-flop IC3 is applied at the point " b ", the field detection signal maintains the high level in the second field as shown in FIG.

On the other hand, at the point "c" of the first field, when the clock signal of the high level of the clock terminal CK3 of the flip-flop IC3 is applied, a low level signal is applied to the input terminal D3 so that the low level is applied to the output terminal Q3. A field detection signal as shown in Fig. 3E is outputted. At the point " d ", the vertical synchronization signal becomes low level and the flip-flop IC3 is preset as above, so the field detection signal is again high level. .

Therefore, when the synthetic synchronous signal is applied to the circuit of the present invention, not only the horizontal synchronous signal and the vertical synchronous signal are detected in the first field and the second field as shown in FIGS. 3 and 2, but also in the first field. As in e), the waveform informing of the first field is output, so that the first field and the second field can be detected.

According to the present invention as described above, by using the digital method through the mono-stable multi-vibrator and flip-flop the vertical synchronization signal, horizontal synchronization signal and field detection signal, the accuracy is higher than the conventional analog detection method The advantage of simple configuration is the use of integrated circuits.

Claims (1)

A monostable multi-vibrator (IC1) for outputting the horizontal synchronizing signal (B) through the inversion output terminal (Q1) at the falling edge of the synthetic synchronizing signal (A) using the synthetic synchronizing signal (A) as an input signal (A1) and And outputting the pulse signal C through the inverted output terminal Q2 at the rising edge of the input signal using the output Q1 of the monostable multivibrator IC1 as the input signal B2. A vertical synchronizing signal D using the IC2 and the horizontal synchronizing signal which is an output signal of the monostable multivibrator IC1 as the clock signal CK4 and the synthesizing synchronizing signal A as the input signal D4. Is a clock signal CK3, and the composite synchronous signal A is inputted as a flip-flop IC4 for outputting ") and a pulse C output from the output terminal Q2 of the monostable multivibrator IC2. A flip that is a signal D3 and is preset by the vertical synchronization signal D output from the flip-flop IC4 and outputs a field detection signal E Rob horizontal and vertical synchronization of the video signal being configured to (IC3) signal and a field detection circuit.