JPH01279691A - Video signal selecting device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory reproduced picture without any misregistration by directly inputting a luminance signal from the luminance signal output of a seperating circuit to separate a composite signal into the luminance signal and a chrominance signal to a switching circuit and installing a first delay means in a path for supplying the luminance signal from the above-mentioned switching circuit to a video and chrominance signal processing circuit. CONSTITUTION:At the side of a comb line filter 6 for a luminance signal/color signal (Y/C) switching circuit 9, the Y signal separated at the comb line filter 6 is directly inputted to the Y/C switching circuit 9 without passing through a delay line 10 as a first delay means. The delay line 10 as the first delay means is installed between a point A at which a signal from the Y/C switching circuit 9 to a synchronization processing circuit 14 and a delay line 12. Further, a delay line 16 as a second delay means is installed in a line for the C signal from a separating terminal 1 to the Y/C switching circuit 9. Since the title device is composed in this manner, and since the signal for Sync to be inputted to the synchronization processing circuit 14 is fetched out of the Y signal before passing through the delay line 10, a burst signal can be completely sampled, and the burst signal never influences a color erasing level and a hue change.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video signal selection device used in AV equipment compatible with the 5-VH5 system.

2. Description of the Related Art In recent years, an increasing number of television receivers are equipped with terminals for receiving input signals from external equipment. The signal given to this input terminal is an audio signal.

A luminance signal (hereinafter referred to as Y signal) and a color signal (hereinafter referred to as C
It is called Shinkan. ) is a composite signal, RG
This is the B signal. Ma? ,=,5-VH of high-resolution system
As seen in the 5 system, external equipment that outputs the video signal in a state where it is separated into a Y signal and a C signal has appeared, and this 5 system
- In order to comply with the VH5 system, television receivers equipped with separate terminals for inputting the Y signal and C signal have appeared. Two typical examples of the configuration are shown in FIGS. 3 and 4.

In Fig. 8, a 5-VH5 system video tape recorder V1 is connected to a separate terminal of a television receiver TV, and a normal VH5 system video tape recorder V1 is connected to a separate terminal of a television receiver TV.
2 is connected to terminal 2. A composite signal switching circuit 5 selects one of the detected television composite signal 3 and the video composite signal 4 from the video tape recorder v2 that have passed through the built-in tuner of the television receiver. The selected composite signal is input to a comb filter 6 as a Y/C separation circuit, where it is separated into a Y signal and a C signal. The C signal separated by the comb filter 6 passes through a signal 7 to be used as a synchronization signal (hereinafter referred to as a 5sync signal) and a bandpass filter (not shown) to produce only 3.58MH2 components. The resulting signal 8 is divided into two parts and input to the Y/C switching circuit 9.

The Y signal separated by the comb filter 6 is input to the Y/C switching circuit 9 via a delay line 0 for compensating the delay of the C signal. This Y/C switching circuit 9 receives the C signal and Y signal from the separate terminal 1 as well as the 5sync signal 11 made from the Y signal. One Y signal, C signal, and 5sync signal on the side of separate terminal 1 are selected.

The selected Y signal is sent to the video/color signal processing circuit 18 via the delay line 2 for aperture control.
The C signal is not directly supplied to the video/color signal processing circuit 13,
The 5sync signal is supplied to the video/color signal processing circuit 13 via the synchronization processing circuit 14. As a result, the TV composite signal 3, the video composite signal 4 selected by the composite signal switching circuit 5 and the Y/C switching circuit 9, and the separate terminal The content of one of the signals from ] is displayed.

Although an example in which delay lines 10 and 12 are provided is explained here, delay lines 12 and 12 are provided to improve image quality.
may not be included.

FIG. 4 shows another conventional example, which differs from FIG. 8 only in the way the 5sync signal is extracted. In this figure 4, Y/C
The 5ync signal is obtained from the Y signal selected by the switching circuit 9 and input to the synchronization processing circuit 4, so there is no need to create the 5ync signal 7.1 on the input side of the Y/C switching circuit 9. This has the advantage of simplifying the circuit. In addition, in this way of extracting the 5 sync signal, there is also an example in which a delay line is inserted into the Y signal from separate terminal 1 to accurately match the delay time of the Y signal and C signal from the separate terminal. be.

Problems to be Solved by the Invention In the configuration shown in FIG. 3, there is a problem that the horizontal position of the signal from the separate terminal and the signal passed through the comb filter 6 are shifted when the same screen is viewed. This will be explained with reference to FIG. FIG. 5(a) shows the Y/C switching circuit 9
Figure 5(b) shows the relationship between the Y signal and the 5sync signal 1 on the side of the separate terminal of the Y/C switching circuit 9.
The relationship between the 5sync signal 7 and the Y signal on the comb filter 6 side is shown. In FIGS. 5(a) and 5(b), the Y signal on the side of the comb filter 6 lags behind the Y signal on the side of the separate terminal by d by the amount that it passes through the delay line 0. Therefore, when the comb filter 6 side is selected, the horizontal position shifts. Although FIG. 5(c) shows a burst signal, this is no different from normal and causes no problem.

In the configuration shown in FIG. 4, the Y signal and the 5sync signal are taken from the same point on the output side of the Y/C switching circuit 9, so the Y/C switching circuit as shown in FIG. However, when the Y/C switching circuit 9 is switched to the comb filter 6 side, the 5 sync signal is taken from the Y signal passing through the delay line 10, so the C lags behind the Y signal.In other words, the synchronous processing circuit]4 separates from the Y signal.
Differentiate the ync signal and extract burst pulse 1
5, the burst signal is delayed from the normal phase, and the burst signal cannot be completely extracted, resulting in a situation where it is not possible to extract the several waves before the burst signal, as shown in Figure 6 (c). , depending on its level, it affects the color erasure level and hue change.

In the present invention, the Y/C switching circuit is placed on the separate terminal side,
To provide a video signal selection device which does not cause a horizontal position shift of a screen when switching to a separation circuit side and can accurately extract a burst signal extraction pulse without delaying its phase.

Means for Solving the Problems The video signal selection device of the present invention has a separation circuit that separates a composite signal into a luminance signal and a color signal, which outputs a luminance signal, one color signal output, and a luminance signal and one color signal input from a separate terminal. A switching circuit selects one of these and supplies it to the video/chrominance signal processing circuit, and a luminance signal is directly input from the Qir luminance signal output to the switching circuit, and the switching circuit outputs the luminance signal to the video/color signal processing circuit. interposing a first delay means in the supply path of the luminance signal to the circuit, inputting the luminance signal before passing through the first delay means on the output side of the switching circuit to the synchronous processing circuit;
A burst signal extraction pulse generated at the output of the synchronous processing circuit is input to the video/color signal processing circuit, and a second delay means is interposed at the color signal input on the separate terminal side of the switching circuit. .

Effect: According to this configuration, before the Y signal passes through the first delay means for compensating the delay of the C signal, the switching circuit separates the Y signal on the pre-circuit side, the C signal and the separate terminal. One of the C signals is selected, and the Y signal after passing through the switching circuit Δ is provided with a first delay means for compensating for the delay of the C signal, and passes through the first delay means on the output side of the switching circuit. A burst signal extraction pulse is created from the Y signal before the burst signal.

EXAMPLE Hereinafter, an example of the present invention will be explained based on FIGS. 1 and 2. Components having the same functions as those in FIGS. 3 and 4 showing the conventional example will be described with the same reference numerals.

FIG. 1 shows a television receiver equipped with a video signal selection device of the present invention. In Figure 1, Y/
From the Y signal on the output side of the C switching circuit 9 to the same loop processing circuit 14
is creating burst signal extraction pulse 15, but Y
On the side of the comb filter 6 of the /C switching circuit 9, the Y signal separated by the comb filter 6 is directly passed through the Y/C switching circuit 9 without going through the delay line lO as the first delay means.
has been entered. The delay line ]0 of the first delay means is interposed between the point A, where the signal from the Y/C switching circuit 9 to the synchronization processing circuit ]4 is taken out, and the delay line ]2. Furthermore, a delay line 6 serving as a second delay means is interposed on the C signal line from the separate terminal 1 to the Y/C switching circuit 9.

With this configuration, the 5sync signal input to the synchronization processing circuit ]4 is the Y before passing through the delay line ]0.
Since it is extracted from the signal, the burst signal can be completely extracted and does not affect the color erasure level or hue change. In FIG. 2(a), the Y/C switching circuit 9 selects the signal on the separate terminal] side, and the 5sync signal and Y signal are selected. The 5 sync signal and the Y signal at the time of t are shown, and it can be seen that there is no horizontal position shift between the two.
) shows a burst signal, and it can be seen that it can be extracted without the wave dropout seen in FIG. 6(c). Note that the delay line 1 is connected to the Y signal output from the Y/C switching circuit 9.
0 to compensate for the delay of the C signal, the delay line ]O acts even when the separate terminal ] side is selected in the Y/C switching circuit 9. The delay time of the Y signal and the C signal is adjusted by applying the relay line 16 to the C signal from the separate terminal 1.

Although the delay line 12 is interposed in the above embodiment, it can be omitted if aperture control for improving image quality is not performed, and the delay line 10.
Alternatively, a single delay line having the same total delay time can be used instead.

Effects of the Invention As described above, according to the present invention, from the luminance signal output of the separation circuit that separates a composite signal into a luminance signal and a chrominance signal,
A luminance signal is input directly to the switching circuit, and a first
Since the delay means is provided, even if the switching circuit is operated to switch between the Y and C signals from the separation circuit and the separate terminals, no horizontal positional shift occurs on the display screen. Moreover, since the burst signal sampling pulse is generated by the synchronous processing circuit from the Y signal before passing through the first delay means on the output side of the switching circuit, it is possible to generate an accurate burst sampling pulse that completely detects the burst signal. When the switching circuit selects the separation circuit side, a good reproduced image can be obtained without affecting the color erasure level or hue change.

Furthermore, since the second delay means is interposed in the color signal input on the separate terminal side of the switching circuit, when the switching circuit selects the separate terminal side, the first delay means It is possible to compensate for the delay in the Y signal caused by the arrangement at the latter stage, and a good reproduced image can be obtained regardless of the switching state of the switching circuit.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an embodiment of the video signal selection device of the present invention, FIG. 2 is a waveform diagram of the main part of FIG. 1, and FIGS. 8 and 4 are configuration diagrams of conventional video signal selection devices, respectively. , FIG. 5 and FIG. 6 are waveform diagrams of the main parts of FIG. 8 and FIG. 4, respectively. 1... Separate terminal, 8... TV composite signal, 6... Comb filter [minute Il [circuit], 9...
... Y/C switching circuit [switching circuit"1.10.15... Delay line [first and second delay means], ]8... Video/color signal processing circuit, ]4... Synchronization processing circuit , 15... Burst signal extraction pulse.

Claims (1)

[Claims] 1. A switching circuit selects one of the luminance signal output and chrominance signal output of the separation circuit that separates the composite signal into a luminance signal and chrominance signal, and the luminance signal and chrominance signal input from the separate terminal, In addition to supplying the luminance signal to the color signal processing circuit, the luminance signal is directly input from the luminance signal output of the separation circuit to the switching circuit, and a first The luminance signal before passing through the first delay means is input to the synchronization processing circuit on the output side of the switching circuit, and the burst signal extraction pulse generated at the output of the synchronization processing circuit is used as the video/color signal. A video signal selection device in which a second delay means is interposed in the color signal input to the signal processing circuit and on the separate terminal side of the switching circuit.