JPH01200889A - Video switching device - Google Patents

Abstract

PURPOSE:To overcome the out-of synchronism of a color television receiver by switching a signal obtained by the Y/C separation of a composite signal and a Y/C separating signal by the duty of a half cycle. CONSTITUTION:The rectangular wave signal of H/2 cycle synchronizing with a horizontal synchronizing signal or the rectangular wave signal of a specific cycle such as V/2 cycle synchronizing with are outputted to a control circuit 15 to switch and control a Y/C switch circuit 7 and output the signal obtained by separating the composite signal from the Y/C switch circuit 7 in a Y/C separating circuit 4 and the Y/C separating signal. Since the Y/C separating signal and the composite signal are the same information originally, even when they are switched for every H/2 cycle, the out-of synchronism is not generated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a color television equipped with a Y/C separate input such as a 5-VIDEO input terminal and a composite input terminal that receives a composite input having the same content. The present invention relates to a video switch device.

[Conventional technology]

FIG. 2 is a block diagram showing a conventional video switch device. In this figure 2, 1 is a Y input terminal for Y/C separate input, 2 is a C input terminal, and 3 is a composite input terminal, and a Y/C separation circuit 4 is connected to this composite input terminal 3. . A Y signal Ya separated from the composite input signal is outputted to a Y output terminal 5 of this Y/C separation circuit 4, and a C signal Ca is outputted from a C output terminal 6.

The Y signal Ya and C signal Ca are input to the Y input terminal 9 and C input terminal 11 of the Y/C switch circuit 7, respectively.

The Y/C switch circuit 7 is also provided with a Y input terminal 8 and a C input terminal 10 . The C signal inputted from the C input terminal 2 is introduced.

The Y/C switch circuit 7 is provided with an input switching terminal 14, and a control circuit 16 is connected to the input switching terminal 14.

Furthermore, the Y/C switch circuit 7 includes a Y output terminal 12,
A C output terminal 13 is provided, and this Y output terminal 12
The Y signal Yb switched from is output, and the C output terminal 13
The switched C signal cb is output from the switch.

Next, the operation will be explained. Y/C separate human input signals are input from Y input terminal 1 and C input terminal 2, respectively.
Y input terminal 8 and C input terminal 10 of Y/C switch circuit 7
will be introduced in

On the other hand, the composite signal is inputted to the Y/C separation circuit 4, and outputted from the Y output terminal 5 as the Y signal Ya, and the C output 0:
The signals are introduced as C signals Ca from the eleventh element 6 to the Y input terminal 9 and the C input terminal 11 of the Y/C switch circuit 7, respectively.

The Y/C switch circuit 7 receives direct current control from a control circuit 16 introduced into the input switching terminal 14, and
Therefore, the Y signal or Y signal Ya is output as the Y output Yb.

Similarly, the C signal cb is output from the C output terminal 13.
Outputs signal C or C signal Ca.

[Problem to be solved by the invention]

Since the conventional video switch device is constructed as described above, there is a problem in that a time lag occurs when comparing the Y/C separate signal and the composite signal, and the color television receiver is also out of synchronization.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a video switching device that can simultaneously display Y/C separate signal input and composite signal input on a color television receiver. do.

[Means to solve the problem]

The video switch device according to the present invention includes a control circuit that controls switching between a signal obtained by Y/C separating a composite signal and a Y/C separate signal with a duty of half a cycle in synchronization with a horizontal synchronizing signal or a vertical synchronizing signal. It was established.

[Function] The control circuit according to the present invention has a control circuit synchronized with a horizontal synchronization signal.
A rectangular wave signal of 172 cycles or a specific cycle such as V/2 frequency synchronized with a vertical synchronization signal is output to control the switching of the Y/C switch circuit, and the Y/C switch circuit Outputs a Y/C separated signal of a composite throat signal and a Y/C separate signal.

[Embodiments] Hereinafter, embodiments of the video switch device of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of one embodiment. In FIG. 1, the parts indicated by reference numerals 1 to 14 are the same as those of the conventional video switch device shown in FIG. 2, and therefore their explanation will be omitted.

Here, 15 is the input switching terminal 1 of the Y/C switch circuit 7.
4, and the horizontal open 3t11 signal (
A rectangular wave signal of pulse 1 [] with a cycle of 1!72 is synchronized with the pulse signal (not shown).

With this configuration, the Y/C switch circuit 7
) The Y signal Y, the C signal C or the composite signal is separated by the Y/C separation circuit 4 every I/2 period, and the Y signal Ya is
The C signal Ca is output from the Y output terminal 12 and the C output terminal 13.

Here, since both the Y/C separate signal and the composite signal are originally the same information, even if they are switched every H/2 cycles, synchronization disturbance will occur in color television receivers that work with the same synchronization signal. do not have.

That is, for example, the left half is an image reproduced by inputting a Y/C separate signal, and the right half is an image reproduced by inputting a composite signal, which can be reproduced at the same time.

It should be noted that if the control circuit 15 outputs a rectangular wave signal in a pulse of V/2 period synchronized with a vertical synchronization signal (not shown), the above-mentioned left-right relationship becomes a vertical relationship. Not even.

Further, in the above embodiment, the Y/C separation circuit 4 is shown as a block, but it may be a rectangular filter or may be one using a chroma trap chroma band pass filter, with the same effect. play.

[Effects of the Invention] As described above, according to the present invention, the Y/C switch circuit is switched in synchronization with a specific timing such as a horizontal synchronization signal or a vertical equal amount signal to generate a composite signal. Since the Y/C separated signal and the Y/C separate signal are configured to be switched periodically, they can be operated in a time-sharing manner, so that the reproduced image by the Y/C separate signal and the reproduced image by the composite signal are They can be reproduced simultaneously at low cost, and have the effect of eliminating synchronization disturbances in color television receivers.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a video switch device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional video switch device. 1.8.9...Y input terminal, 2.10.11...C
Input terminal, 3...Composite input terminal, 4...Y
/C separation circuit, 5.12...Y output terminal, 6.13.
...C output terminal, 7...Y/C switch circuit, 14.
...Input switching terminal, 15...Control circuit. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Masu Oiwa Figure 1□C Figure 2 y t Ct L3 t-p, q: Y' input gu bird) 75 Bonito 1 f: P I: E) ik; b

Claims (1)

[Claims] In a color television receiver equipped with respective input terminals for a composite signal and a Y/C separate signal, and a Y/C separation circuit for the composite signal, a signal obtained by Y/C separating the composite signal and the Y/C separate signal A Y/C switch circuit performs a switching operation, and the Y/C switch circuit periodically switches and outputs the Y/C separated signal of the composite signal and the Y/C separate signal at a specific timing. 1. A video switch device comprising: a control circuit for controlling the video switch device.