JPH07283966A - Composite synchronizing signal processing circuit - Google Patents

Abstract

PURPOSE:To realize simple circuit configuration by which a vertical synchronous pulse can be taken out of a composite synchronizing signal. CONSTITUTION:This circuit is equipped with a monostable multivibrator 3 which produces a horizontal synchronous pulse from the composite synchronizing signal, a NOR gate 12 which inputs the horizontal synchronous pulse of the monostable multivibrator 3 and the composite synchronizing signal and outputs the vertical synchronous pulse from the composite synchronizing signal, a second monostable multivibrator 6 constituted so as to delay the horizontal synchronous pulse of the monostable multivibrator 3 and to vary delay quantity, and a second NOR gate 9 which reproduces the composite synchronizing signal from the output of the second monostable multivibrator 6 and that of the NOR gate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite sync signal processing circuit having a simple structure for obtaining a signal capable of changing only a horizontal sync position from a composite sync signal.

[0002]

2. Description of the Related Art FIG. 4 shows a conventional composite sync signal processing circuit. In the figure, 1 is a composite sync signal input terminal, 2 is a horizontal sync separation circuit for separating a horizontal sync pulse from the composite sync signal, 3 is a first mono-multi vibrator for producing a delayed pulse from the horizontal sync pulse, and 4 is this mono-multi vibrator. A time constant capacitor that determines the delay time of the vibrator, 5 is also a time constant resistor, and 6 is a second monomulti that further delays the pulse delayed by the first monomultivibrator 3 and makes the delay amount variable. A vibrator, 7 is a time constant capacitor that determines the delay amount of the mono-multi vibrator 6, 8 is a time constant variable resistor that also makes the time constant variable, and 9 is a NOR gate for producing a composite synchronizing signal again. Reference numeral 10 is a vertical sync separation circuit for separating a vertical sync pulse from the composite sync signal input to the input terminal, and its output is applied to one end of the NOR gate 9. Reference numeral 11 is an output terminal for a composite synchronizing signal (after processing).

Next, the operation of FIG. 4 will be described with reference to FIG. FIG. 5 shows the waveforms of the signals F to K in FIG. 4, where (a) is the waveform of the first field and (b) is the waveform of the second field. The composite sync signal F input to the composite sync signal input terminal 1 is input to the horizontal sync separation circuit 2 and the vertical sync separation circuit 10. The horizontal sync separation circuit 2 separates the composite sync signal from the horizontal sync and outputs a horizontal sync pulse G.
The horizontal synchronizing pulse G is input to the mono-multivibrator 3 and delayed in accordance with the time constant determined by the capacitor 4 and the resistor 5 to generate a horizontal synchronizing pulse H which is delayed by about 1H from the horizontal synchronizing pulse G. Further, the horizontal sync pulse H is input to the second mono-multivibrator 6 and delayed to become a horizontal sync pulse I. Here, the delay amount by the second mono-multivibrator 6 is determined by the time constant capacitor 7 and the time constant variable resistor 8. Therefore, the pulse position of the horizontal synchronizing pulse I is adjusted by changing the time constant variable resistor 8.

On the other hand, the composite sync signal F is vertically sync separated in the vertical sync separation circuit 10 and output as a vertical sync pulse J. The vertical sync separation system here generally uses an integrating circuit. The vertical synchronizing pulse J and the horizontal synchronizing pulse I thus produced are input to the NOR gate 9, and the composite synchronizing signal (after processing) K whose horizontal synchronizing pulse position is adjusted is taken out from the output terminal 11.
Note that, in FIG. 5, the portion indicated by the broken line is the time constant variable resistor 8
This is the part where the pulse position can be changed.

[0005]

Since the conventional composite sync signal processing circuit forms a composite sync pulse by the above-mentioned structure, the circuit structure is complicated and only the horizontal sync pulse position can be varied. In order to reproduce the synchronization signal, an IC-based synchronization separation circuit or a complicated circuit is required, which causes a problem of high cost.

The present invention has been made to solve the above problems, and an object thereof is to obtain an inexpensive composite synchronizing signal processing circuit with a simple structure.

[0007]

A composite sync signal processing circuit according to the present invention inputs a mono-multivibrator which produces a horizontal sync pulse from a composite sync signal, and a horizontal sync pulse of the monomultivibrator and the composite sync signal. However, a NOR gate for outputting a vertical sync pulse from the composite sync signal and a second mono multivibrator for delaying the horizontal sync pulse of the mono multivibrator and changing the delay amount are provided. is there.

Furthermore, a second NOR gate for reproducing a composite synchronizing signal from the output of the second mono-multivibrator and the output of the NOR gate is provided.

[0009]

In the composite sync signal processing circuit according to the present invention, the horizontal sync pulse is generated from the composite sync signal by the mono-multivibrator, and the NOR gate is used to mask the horizontal sync of the composite sync signal with the horizontal sync pulse. The vertical sync pulse is taken out by means of, and at the same time, the second mono multivibrator connected to the mono multivibrator adjusts the delay amount of the horizontal sync pulse to make only the position of the horizontal sync pulse variable. Also, the output of the second mono-multivibrator and the output of the NOR gate are added to the second NOR gate to reproduce a composite synchronizing signal with adjustable horizontal synchronizing pulse position.

[0010]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a composite sync signal input terminal, 3 is a first mono-multivibrator that produces a delay pulse from a horizontal sync signal, 4 is a time constant capacitor that determines the delay time of this mono-multivibrator 3, and 5 is the same time. A constant resistance 6 is a second mono-multivibrator 7 which is adapted to delay the pulse delayed by the first mono-multivibrator 3 and change the delay amount.
Is a time constant capacitor that determines the delay amount of the mono-multivibrator 6, 8 is a time constant variable resistor that also makes the time constant variable, and 9 is a second time constant for producing a composite synchronizing signal again.
Is a NOR gate. Reference numeral 12 is a first NOR gate to which the composite synchronizing signal from the input terminal 1 and the output of the first mono-multivibrator 3 are applied.
It is added to one end of the OR gate 9. Reference numeral 11 is an output terminal for taking out the composite synchronizing signal (after processing).

Next, the operation will be described. FIG. 2 shows the waveforms of the signals A to E in FIG. 1, where (a) is the waveform of the first field and (b) is the waveform of the second field. The composite sync signal A input to the composite sync signal input terminal 1 is input to the first mono-multivibrator 3 to generate a horizontal sync pulse B delayed by about 1H. Here, the delay amount of the first mono-multivibrator 3 is determined by the time constant capacitor 4 and the time constant resistor 5, and is set to about 1H. For this reason, it is not triggered by the equivalent pulse, but is triggered by pulls of 1H period during the vertical synchronization period, and the horizontal synchronization pulse B can be formed. The horizontal sync pulse B is input to the second mono-multivibrator 6, where a further delayed horizontal sync pulse C is produced. Here, since the delay amount of the second mono-multivibrator 6 is determined by the time constant capacitor 7 and the time constant variable resistor 8, the position of the horizontal synchronizing pulse should be adjusted by changing the time constant variable resistor 8. You can

On the other hand, since the first NOR gate 12 receives the composite sync signal A from the input terminal 1 and the horizontal sync pulse B delayed by 1H, the horizontal sync signal portion of the composite sync signal A is input. Masked by the horizontal sync pulse B,
The vertical synchronizing pulse D is obtained from the NOR gate 12. The horizontal synchronizing pulse C and the vertical synchronizing pulse D thus generated are input to the second NOR gate 9, and the output terminal 11 obtains the composite synchronizing signal E (after processing) whose horizontal synchronizing pulse position is adjustable. To be In addition, in FIG. 2, a portion indicated by a broken line is a portion where the pulse position is changed by the time constant variable resistor 8.

Example 2. In the first embodiment, the horizontal sync pulse C
In this embodiment, the vertical sync pulse D and the vertical sync pulse D are input to the NOR gate to obtain the composite sync signal (after processing). However, as shown in FIG. 3, the second NOR gate is omitted and the horizontal sync pulse is generated. C and the vertical synchronizing pulse D may be taken out separately and may be configured to interface with the subsequent system.

[0014]

As described above, according to the present invention, a horizontal synchronizing pulse is generated from a composite synchronizing signal by a mono-multivibrator, and the horizontal synchronizing pulse is masked by the horizontal synchronizing pulse to obtain a vertical synchronizing pulse. In addition, since the position of the horizontal sync pulse from the mono multivibrator is variably adjusted, only the horizontal sync position can be made variable, and by combining the vertical sync pulse and the horizontal sync pulse, the horizontal configuration can be made simple. A composite sync signal with variable sync position can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a composite synchronizing signal processing circuit according to a first embodiment of the present invention.

FIG. 2 is a waveform chart of each part in the circuit of the first embodiment.

FIG. 3 is a circuit diagram showing a composite synchronizing signal processing circuit according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional composite sync signal processing circuit.

FIG. 5 is a diagram showing waveforms at various parts of a conventional composite synchronization signal processing circuit.

[Explanation of symbols]

 1 Composite Sync Signal Input Terminal 3 First Mono Multivibrator 4 Time Constant Capacitor 5 Time Constant Resistor 6 Second Mono Multivibrator 7 Time Constant Capacitor 8 Time Constant Variable Resistor 9 Second NOR Gate 11 Composite Sync Signal Output Terminal 12 First NOR gate

Claims (2)

[Claims] 1. A first mono-multivibrator for producing a horizontal sync pulse from a composite sync signal, an output pulse of the first mono-multivibrator and the composite sync signal being input, and a vertical sync pulse being generated from the composite sync signal. A composite synchronizing signal processing circuit comprising: a gate unit for outputting the output pulse; and a second mono-multivibrator for delaying the output pulse of the first mono-multivibrator and changing the delay amount. 2. A first mono-multivibrator for producing a horizontal sync pulse from a composite sync signal, an output pulse of the first mono-multivibrator and the composite sync signal being input, and a vertical sync pulse being generated from the composite sync signal. A first gate means for outputting, a second mono-multivibrator for delaying the output pulse of the first mono-multivibrator and changing the delay amount thereof, the second
7. A composite synchronizing signal processing circuit, comprising: second gate means for producing a composite synchronizing signal from the output of the mono-multivibrator and the output of the first gate means.