JPH1155596A - Video signal output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit the information of an image mode even about an unmodulated signal by superimposing direct current voltage that corresponds to an image mode in an synchronous interval of a horizontal synchronizing signal of a luminance signal on a chrominance signal or a color-difference signal. SOLUTION: A 1st color-difference signal that is outputted from a clamp circuit 1 is outputted through a voltage superimposed circuit 7, a 2nd color- difference signal is outputted through a voltage superimposed circuit 6 and a Y signal is just outputted. An image mode sending part 4 inputs image mode information to a direct current voltage generation circuit 5. The part 4 can decide the form (image mode) of a video signal by inputting, e.g. a video signal. The circuit 5 inputs direct current voltage that corresponds to inputted image mode information to the circuits 6 and 7. The circuits 6 and 7 superimpose direct current voltage which is inputted only in a synchronous interval of a horizontal synchronizing signal on the 1st and 2nd color-difference signals and output them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video signal output device for outputting component signals such as a luminance signal and a color difference signal.

[0002]

2. Description of the Related Art Recently, a conventional aspect ratio of 4:
In addition to the video signal of No. 3, a so-called squeeze signal obtained by compressing a horizontally long image having an aspect ratio of 16: 9 into a left-right method, or a non-image portion (black band) is provided at the top and bottom of a horizontally long image having an aspect ratio of 16: 9. With the emergence of letterbox signals, the form of video signals is diversifying.

[0003] In a television receiver, a display device, or the like that projects video signals of these various modes,
It is necessary to display an image in an optimal state according to each mode. That is, the aspect ratio of the screen is 16:
In the case of 9, when a normal image having an aspect ratio of 4: 3 is input, the image is compressed and displayed at the center in the left-right direction or expanded only at the left and right ends and displayed on the entire screen, and the squeeze signal is displayed. When an image of a letterbox signal is input, the image is expanded in the left-right direction and displayed on the entire screen. When an image of a letterbox signal is input, the image is expanded in the vertical direction and displayed on the entire screen.

As described above, in order to display an image in an optimal state in accordance with the mode of the image signal, the image signal is input using a so-called S terminal for separating and inputting a luminance signal and a modulated color signal. In such a case, a DC voltage corresponding to a mode (image mode) of a video signal is superimposed on the color signal, and the image mode is determined based on the DC voltage. According to this, since the image mode can be automatically determined in the television receiver, the display device, or the like, it is possible to save the trouble of the user manually switching the aspect.

[0005]

However, the above-described conventional image mode discrimination method of superimposing a DC voltage is effective for a color signal having a frequency component as high as several MHz which has been modulated. Since it is difficult to superimpose a DC voltage on a color signal or color difference signal which is not applied, it cannot be used for a signal which is not modulated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a video signal output device capable of transmitting image mode information even to a signal that is not modulated. I do.

[0007]

According to the present invention, there is provided a video signal output device for outputting a luminance signal and a chrominance signal or a color difference signal. A video signal output device provided with a voltage superimposing circuit for superimposing a DC voltage according to an image mode on a color difference signal during a synchronization period of a horizontal synchronization signal of the luminance signal; In a video signal output device that outputs a signal and a color signal or a color difference signal, a signal superposition that superimposes a single frequency signal according to an image mode on the color signal or the color difference signal during a synchronization period of a horizontal synchronization signal of the luminance signal. A video signal output device provided with a circuit is provided.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a video signal output device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing a first embodiment of the video signal output device of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the first embodiment of the video signal output device of the present invention, and FIG. 2 is a block diagram showing a second embodiment of the video signal output device, and FIG. 2 is a waveform diagram for explaining the operation of the second embodiment of the video signal output device of the present invention.

<First Embodiment> In FIG. 1, first and second color difference signals and a luminance (Y) signal are input to a clamp circuit 1. The first color difference signal is, for example, U, Pb, C
b. The second color difference signal is, for example, V, P
r and Cr. That is, in the clamp circuit 1,
One set of color difference signals U and V and Y signal, and one set of Pb and Pr
One of a set of color difference signals and Y signals, and one set of color difference signals and Y signals of Cb and Cr is input.

The Y signal is also input to the sync separation circuit 2, which separates the horizontal sync signal and the vertical sync signal from the Y signal. These synchronization signals are input to the clamp circuit 1 and the voltage superimposing circuits 6 and 7. The clamp voltage generation circuit 3 supplies a clamp voltage to the clamp circuit 1. The clamp circuit 1 receives the input first and second color difference signals and Y
The signal is clamped to a DC voltage value defined by the clamp voltage input from the clamp voltage generation circuit 3 and output.

The first color difference signal output from the clamp circuit 1 is output via a voltage superposition circuit 7, the second color difference signal is output via a voltage superposition circuit 6, and the Y signal is output as it is. Note that one of the voltage superimposing circuits 6 and 7 can be omitted.

Further, the image mode sending section 4 inputs the image mode information to the DC voltage generating circuit 5. The image mode sending unit 4 can determine the mode (image mode) of the video signal by inputting the video signal, for example. The DC voltage generating circuit 5 inputs a DC voltage corresponding to the input image mode information to the voltage superimposing circuits 6 and 7. The voltage superimposing circuits 6 and 7 superimpose the DC voltage input only during the synchronization period of the horizontal synchronizing signal on the first and second color difference signals and output.
Note that the voltage superposition circuits 6 and 7 can be configured by, for example, switches.

The operation of the first embodiment shown in FIG. 1 will be further described with reference to FIG. In FIG.
(A) is a Y signal, (B) is a normal color difference signal in which a DC voltage is not superimposed during a synchronization period, and (C) is a voltage superimposition circuit 6, 7.
Indicates a color difference signal in which a DC voltage is superimposed during the synchronization period. In the present embodiment, a color difference signal is described, but a color signal may be used. Further, the present invention can be applied to a modulated signal.

As described above, according to the first embodiment, image mode information can be transmitted even for a signal that is not modulated.

<Second Embodiment> In the second embodiment shown in FIG. 3, the same parts as those in the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. In FIG. 3, the image mode transmitting section 4 inputs image mode information to the pilot signal generation circuit 15. The pilot signal generation circuit 15 inputs an arbitrary single frequency signal corresponding to the input image mode information to the signal superposition circuits 16 and 17. Signal superposition circuit 16,
Reference numeral 17 superimposes the single frequency signal input only during the synchronization period of the horizontal synchronization signal on the first and second color difference signals and outputs the resultant signal. Note that the signal superimposing circuits 16 and 17 can be configured by, for example, switches. Here, either one of the signal superimposing circuits 16 and 17 can be omitted.

The operation of the first embodiment shown in FIG. 3 will be further described with reference to FIG. In FIG.
(A) is a Y signal, (B) is a normal color difference signal in which a single frequency signal is not superimposed in a synchronization period, and (C) is a color difference in which a single frequency signal is superimposed in a synchronization period by the signal superimposition circuits 16 and 17. The signal is shown. In the present embodiment, a color difference signal is described, but a color signal may be used. Further, the present invention can be applied to a modulated signal.

As described above, according to the second embodiment, image mode information can be transmitted even for a signal that is not modulated. Further, when the second embodiment is applied to a modulated color signal, image mode information can be recorded on a video recording medium capable of recording and reproducing the Y signal and the modulated color signal. Therefore, it is also possible to provide image mode information to a video output from a VTR or the like.

[0018]

As described in detail above, the video signal output device of the present invention provides a voltage for superimposing a DC voltage corresponding to an image mode on a color signal or a color difference signal during a synchronization period of a horizontal synchronization signal of a luminance signal. Since a superimposing circuit and a signal superimposing circuit for superimposing a single frequency signal according to the image mode are provided, the information on the image mode can be transmitted even to a signal which is not modulated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a waveform chart for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a waveform chart for explaining the operation of the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clamp circuit 2 Synchronization separation circuit 3 Clamp voltage generation circuit 4 Image mode transmission part 5 DC voltage generation circuit 6, 7 Voltage superimposition circuit 15 Pilot signal generation circuit 16, 17 Signal superimposition circuit

Claims (2)

[Claims] 1. A video signal output device for outputting a luminance signal and a color signal or a color difference signal, wherein a DC voltage corresponding to an image mode is applied to the color signal or the color difference signal during a synchronization period of a horizontal synchronization signal of the luminance signal. A video signal output device comprising a voltage superimposing circuit for superimposing. 2. A video signal output device for outputting a luminance signal and a color signal or a color difference signal, wherein the color signal or the color difference signal has a single frequency corresponding to an image mode during a synchronization period of a horizontal synchronization signal of the luminance signal. A video signal output device comprising a signal superimposing circuit for superimposing a signal.