JPH0255474A - Horizontal synchronizing signal separation circuit - Google Patents

Abstract

PURPOSE:To prevent the disturbance in a received pattern from the occurrence by separating and outputting a horizontal synchronizing signal with a normal horizontal scanning period separately at all times even if an equalizing pulse of an input composite synchronizing signal is missing due to a fault on transmission or the like. CONSTITUTION:An input composite synchronizing signal (a) inputted to a terminal 1 is supplied to a 1st nonretriggerable monostable multivibrator 5 and a retriggerable monostable multivibrator 6. The monostable multivibrator 5 is triggered at the front ridge of the composite synchronizing signal (a) and outputs a horizontal period signal (d) normally. If missing of an equalizing pulse takes place due to a fault on the transmission or the like, the waveform of the signal (d) is changed. On the other hand, an output (f) of the monostable multivibrator 6 is fed to a 2nd nonretriggerable monostable multivibrator 7, the output (f) of the monostable multivibrator 7 is at an L level normally and when the equalizing pulse is missing, a pulse at an H level for a prescribed period at that time is generated to clear the monostable multivibrator 5. As a result, an output (g) of the monostable multivibrator 3 is outputted as a signal always synchronizing with the horizontal period.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a horizontal synchronization signal separation method for separating and outputting a horizontal synchronization signal from which the effects of equalization pulses, etc. have been removed from a composite synchronization signal in a television receiver or the like. Regarding circuits.

(Prior art) The input composite synchronization signal, which is transmitted by combining the horizontal synchronization signal and the vertical synchronization signal in a television receiver, etc., has a vertical synchronization signal period and three horizontal scanning periods before and after the vertical synchronization signal period (hereinafter referred to as
As is well known, the horizontal synchronizing signal does not have the normal period TH, but the period TH/
The equalization pulse has two periods, and the pulse width is also narrow.

Therefore, horizontal synchronization signal separation circuits that can separate and output horizontal synchronization signals with the same period T+-+ and the same pulse width for the period of these equalization pulses as the normal period have been conventionally used. .

FIG. 4 is a block diagram showing a conventional horizontal synchronizing signal separation circuit, and FIG. 5 is a timing chart for explaining the operation of FIG. 4, which will be explained together.

In Fig. 4, from synchronous signal input terminal 1 to Fig. 5 (A)
An input composite synchronization signal a having a waveform shown in is input and supplied to the non-retriggerable monostable multivibrator 2.

As shown in FIG. 5(A), the horizontal synchronizing signal normally has a period of TH, but the period of the equalization pulse is a period of T)I/2, and the pulse width is also narrow.

The non-retriggerable monostable multivibrator 2 is triggered at the leading edge (rising edge) of the input composite synchronization signal a at time (timing) tl, and becomes a high level as shown in FIG. 5(B). A retrigger is not accepted until the end of the period of pulse width T5, and a non-retriggerable operation is performed in which the level becomes L (low) after the period of pulse width T5 has passed. Then, it is triggered again at time t2 and becomes H level.

Since the pulse width T5 is set to satisfy the relationship TH/2<75<T)l, the rise time t3. At t5, it is not retriggered, and Fig. 5 (B)
An output signal with a period TH is obtained over the entire period shown in FIG.

The output horn signal of the non-retriggerable monostable multivibrator 2 is supplied to a monostable multivibrator 3. The monostable multivibrator 3 may be non-retriggerable or retriggerable.

The monostable multivibrator 3 is triggered at the leading edge (rising edge) of the output signal S with a pulse width T5, and an output signal C with a pulse width T4 shown in FIG. 5(C) is obtained.

This output signal C is a horizontal synchronization signal having a correct horizontal scanning period TH, is supplied to the synchronization signal output terminal 4, and is utilized in a horizontal deflection circuit or the like.

Note that the pulse width T4 of the output signal C of the 1.1 stable lubricating vibrator 3 is set approximately equal to the pulse width of the horizontal synchronization signal in the composite synchronization input signal, as shown in FIG. 5(C). Depending on the application, the pulse width T4 may be appropriately set within the range of O<T4<TLI.

(Problem to be Solved by the Invention) However, as in the equalized pulse shown by the broken line at time t4 in FIG. may be supplied.

In this case, the output j signal of the non-retriggerable monostable multivibrator 2 is not retriggered at time 14, but is retriggered at time t5, as shown in FIG. 5(E).

Therefore, the output signal C of the monostable multivibrator 3 is
As shown in FIG. 5(F), during the period from time t2 to t5,
This results in a period of 3T11/2, which is longer than the normal horizontal scanning period TH by TH/2.

As a result, when this output signal C is used in a horizontal deflection circuit or the like, a problem arises in that the horizontal synchronization of the screen of the television receiver is disturbed.

The present invention has been made with attention to the above points, and even if the equalization pulse of the input composite synchronization signal is missing due to a transmission failure or the like, horizontal synchronization of the normal horizontal scanning period TH is always achieved. It is an object of the present invention to provide a horizontal synchronization separation circuit that can separate and output signals, does not cause disturbance to the screen of a preview receiver, etc., and can solve the problems in the conventional example.

(Means for Solving the Problems) In order to achieve the above object, a first IC is triggered at the leading edge of the input composite synchronization signal and outputs a pulse with a pulse width of 1.
a non-retriggerable monostable multivibrator with a pulse width T2 triggered on the leading edge of the input composite sync signal;
A triggerable monostable multivibrator outputs a pulse of 1 to 1 at the trailing edge of the output signal of the retriggerable monostable multivibrator, and is cleared from the output signal of the first non-retriggerable monostable multivibrator. a second non-retriggerable monostable multivibrator which outputs a pulse with a pulse width T3 and clears the first non-retriggerable monostable multivibrator A7 with this pulse; A monostable multivibrator that is triggered by the leading edge of the output signal of the multivibrator and outputs a pulse with a pulse width T4, and each pulse width T1 to T4 and horizontal scanning period TH are TH/2. <T2
<-“+ <TH1, TH<T2 +73 <3TH/
It is an object of the present invention to provide a horizontal synchronizing signal separation circuit that satisfies the relationship: 2°0<T4<TH.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the horizontal synchronizing signal separation circuit of the present invention, and FIGS. 2 and 3 are timing charts for explaining the operation of FIG. The figure shows normal operation, 3rd
The figure shows the timing when a dropout occurs in the equalization pulse.
- It is. The same parts as in FIGS. 4 and 5 will be described with the same reference numerals.

First, normal operation will be explained. In Figure 1,
An input composite synchronization signal a having a waveform shown in FIG. .

The first non-retriggerable monostable multivibrator 5 is triggered at the leading edge (rising edge) of the input composite synchronization signal a at time t1, and as shown in FIG. level, and does not accept a retrigger until the end of the period of pulse width 1"1, and after the period of pulse width T1 has passed, it becomes L (low) level, performing a non-retriggerable operation.

Then, at time t2, it is triggered again and becomes a trubel.

Since the pulse width T1 is set to satisfy the relationship TH/2<T + <TH, the rise time t3. of every other equalization pulse. At t5, it is not retriggered and the signal shown in Fig. 2 (8
) An output signal d with a period T H is obtained over the entire period shown in ).

On the other hand, the retriggerable monostable multivibrator 6 is
At time t1, d3 is triggered by the leading edge (rising edge) of the input composite synchronization signal a, and as shown in FIG. 2(C), it becomes a torque level, and after outputting a pulse width T2, it becomes I-level. Then, at time t2, it is triggered again and becomes level 14.

The pulse width T2 is TH/2<, T2<T1<
Since the retriggerable monostable multivibrator 6 re-receives the 1-rega signal even during the period when the output is H (high), the relationship between time t3 and t6 is set to be TH.
The output signal e is re-triggered at the leading edge (rising edge) of each equalization pulse, and an output signal e whose torque continues as shown in FIG. 2(C) is obtained.

The output signal e of the retriggerable monostable multivibrator 6 is supplied to a second non-retriggerable monostable multivibrator 7.

The second non-retriggerable, monostable multivibrator 7 is triggered from 1 to 1 at the trailing edge (falling edge) of the output signal e, and outputs a pulse with a pulse width - [3]. The output signal d is supplied to the clear terminal C[, and during the period when the clear terminal C is at the "1" level, the clearing operation is performed and the trigger is not activated.

As is clear from FIGS. 2(B) and 2(C), at the falling time of the output signal e, the output signal d is a torque signal, so the second non-retriggerable monostable multivibrator 7 is not triggered. As a result, as shown in FIG. 2(D), this output signal f maintains the torque level for the entire period.

The output signal f of the second non-retriggerable monostable multivibrator 7 is supplied to the clear terminal CL of the first non-retriggerable monostable multivibrator 5, but since it is a level throughout the entire period, the output signal f of the first non-retriggerable monostable multivibrator 7 is The output signal @d of the triggerable monostable multivibrator 5 is not affected in any way.

The output signal d of the first non-retriggerable monostable multivibrator 5 is supplied to the monostable multivibrator 3.

The monostable multivibrator 3 is triggered by the leading edge (rising edge) of the output signal d with a pulse width T1, and an output signal q with a pulse width T4 shown in FIG. 2 ([) is obtained.

This output signal 0 is a horizontal synchronization signal having the correct horizontal scanning period T H and is supplied to the synchronization signal output terminal 4,
Used in horizontal deflection circuits, etc.

Next, the operation when an input composite synchronization signal whose equalized pulses are partly missing due to a transmission failure or the like is inputted will be explained with reference to the timing chart shown in FIG.

As explained in the conventional example, it is assumed that the snow formation pulse indicated by the broken line at time t4 is missing, as shown in FIG. 3(A).

In this case, the output signal d of the first non-retriggerable monostable multivibrator 5 is not retriggered at time t4 and remains at the L level, as shown in FIG. 3(B).

On the other hand, the retriggerable monostable multivibrator 6 is
Since it is not retriggered at time t4, T+/2MT
It outputs a pulse with a pulse width of 2 and becomes L level, and at time t
5 again]~regained, became H level again, and the second
An output signal e shown in Figure (C) is obtained.

Second non-retriggerable monostable multivibrator 7
is triggered at the trailing edge (falling edge) of a pulse with a pulse width TH/2+T 2 of the output signal e.

At this time, the output signal d supplied to the clear terminal CL is at the L level and no clearing operation is performed, as shown in FIG.
) is obtained as an output signal f having a pulse width T3 as shown in FIG.

The output signal 1'' shown in FIG. 3(D) is supplied to the clear terminal CL of the first non-retriggerable monostable multivibrator 5, and performs a clearing operation during a period of pulse width T3. This pulse width T3 is TH<T2+T3<3T
Since the relationship is set to be H/2, the first non-restable monostable multivibrator 5 is
At time t5, retriggering is not possible, and at time t6, it is retriggered and becomes H level, and output j signal d shown in FIG. 3(B) is obtained.

The output signal d shown in FIG. 3(B) is supplied to the monostable multivibrator 3, which is triggered at the leading edge (rising edge) of the pulse and outputs a pulse with a pulse width T4.
An output signal q shown in Figure (E) is obtained.

The output signal q shown in FIG. 3(E) has a period of 2TH in part due to the loss of the equalization pulse repeated at time t4, and one horizontal synchronizing signal is missing. Unlike the conventional example shown in Figure (F), the deviation of T H/2 does not occur.

As is well known, in the case of simply missing one horizontal synchronizing signal, it does not affect the synchronization at all in television receivers and the like.

Therefore, even if a dropout occurs in the equalization pulse of the input composite synchronization signal, stable synchronization can always be maintained.

(Effects of the Invention) Since the horizontal synchronization signal separation circuit of the present invention is configured as described above, even if the equalization pulse of the input composite synchronization signal is missing due to a transmission failure, etc., the horizontal It has extremely excellent practical effects, such as being able to separate and output horizontal synchronizing signals with a scanning period of TH, eliminating screen disturbances in television receivers, etc., and solving problems associated with conventional methods. .

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the horizontal synchronization signal separation circuit of the present invention, FIGS. 2 and 3 are timing charts for explaining the operation of FIG. 1, and FIG. 4 is a conventional horizontal synchronization signal separation circuit. FIG. 5 is a timing chart for explaining the operation of FIG. 4. 1... Synchronous signal input terminal, 2.5.7... Non-retriggerable monostable multivibrator, 3... Monostable multivibrator, 4... Synchronous signal output terminal, 6.
・・Retriggerable monostable multivibrator, a・・
・Input composite synchronization signal, b-g...output signal, ■1-T
5...Pulse width, TH...Horizontal scanning period, 11~t
6...Time (timing). Patent applicant: Kunio Kakiki, representative of Victor Japan Co., Ltd.

Claims (1)

[Claims] Triggered on the leading edge of the input composite synchronization signal, with a pulse width T_1
a first non-retriggerable monostable multivibrator that outputs a pulse of T, triggered on the leading edge of the input composite synchronization signal and having a pulse width T;
a retriggerable monostable multivibrator that outputs a pulse of _2; and a pulse width T_3 that is triggered by the trailing edge of the output signal of the retriggerable monostable multivibrator and cleared by the output signal of the first non-retriggerable monostable multivibrator. a second non-retriggerable monostable multivibrator that outputs a pulse of and clears the first non-retriggerable monostable multivibrator with this pulse; A monostable multivibrator that is triggered at the leading edge and outputs a pulse with a pulse width T_4, and each pulse width T_1 to T_4 and horizontal scanning period T_H are
T_H/2<T_2<T_1<T_H, T_H<T_2+T_<3T_H/2,0<T_4<T
A horizontal synchronizing signal separation circuit characterized by having a relationship of _H.