JPH0463598B2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention provides a signal that is effective when displaying (superimposing) another system of video, such as data from a personal computer, on a received video screen of television broadcasting. The present invention relates to a superimposing device.

<Background Art> Recently, personal computers have come to be used in general households. Attempts are now being made to connect a home color television receiver as a CRT display device to a personal computer and display data from the personal computer on the screen of the color television receiver. Furthermore, recently, a combination system of a color television receiver and a personal computer has been developed that superimposes data from a personal computer on a color television broadcast screen, and is already commercially available. .

<Disclosure of the Invention> The present invention provides a signal superimposition device suitable for use in such a combination system.

The signal superimposition device of the present invention separates a color composite video signal from a television receiver or the like into a luminance (Y) signal component and a chroma signal component, and further demodulates the chroma signal to reproduce R, G, and B signals. These Y signals, R, G, and B signals are individually added and mixed with each signal of a separate system such as personal computer data to generate one color composite video signal in which two systems of video information are superimposed. .

<Example> The present invention will be described below according to an example shown in the drawings. FIG. 1 is a block diagram showing one embodiment of the apparatus of the present invention, where 1 is a video input terminal, and 2 is a color composite video signal supplied to the input terminal 1, in which only the burst signal component is separated. 3 is a color subcarrier oscillation circuit that oscillates a 3.58MHz color subcarrier signal based on the burst signal separated by the burst gate circuit 2;
4a, 4b, 4c are R, G, B input terminals, 5 is a Y signal generation circuit that generates a Y signal based on the R, G, B signals supplied to the input terminals 4a, 4b, 4c, and 6 is a Y signal generation circuit. A Y-C separation circuit 7 separates the color composite video signal supplied to the input terminal 1 into a Y signal and a chroma signal; 8 is a Y signal mixing circuit for mixing the Y signal
- a demodulation circuit that demodulates the chroma signal separated by the C separation circuit 6 based on the color subcarrier signal obtained from the color subcarrier oscillation circuit 3; 9 is the R, G, B signal obtained from the demodulation circuit 8; and the input terminal 4a,
4b and 4c, and 10 is an R, G, B mixing circuit that individually mixes the R, G, B signals supplied to 4b and 4c; 11 is a Y-C mixing circuit that mixes the Y signal obtained from the Y signal mixing circuit 7 and the chroma signal obtained from the chroma signal generation circuit 10; R is a video signal generating circuit; It is an output terminal.

In the signal superimposing device constituted by the above, a color composite video signal as shown in a○ in Fig. 2 is supplied from a color television receiver to the video input terminal 1, and the R, G, B input terminals Assuming that the R, G, and B signals are supplied from a system separate from the receiver, such as a personal computer, the personal gate circuit 2 first converts the data in the composite video signal as shown in b○ in FIG. Only the burst signal component is separated and derived, and this is supplied to the color subcarrier oscillation circuit 3. On the other hand, Y-C
In the separation circuit 6, as shown in Fig. 2 c○, d○, Y
The signal component and the chroma signal component are separately derived, and the Y signal component is supplied to the Y signal mixing circuit 7 and the chroma signal component is supplied to the demodulation circuit 8. At this time, in the Y signal generation circuit 5, the input terminals 4a, 4
The R, G, and B signals supplied to b and 4c are
The signals are mixed at a ratio of 0.31:0.59:0.11, and a Y signal as shown in e○ in FIG. 2 is generated. In the Y-signal mixing circuit 7, the Y-C separation circuit 6 and the Y-signal generation circuit 5
The two Y signals obtained from the above are mixed as shown in Fig. 2.
A composite Y signal as shown in is obtained. On the other hand, the color subcarrier oscillation circuit 3 oscillates a continuous color subcarrier signal of 3.58 MHz that matches the frequency and phase of the burst signal, and supplies this to the demodulation circuit 8 and the chroma signal generation circuit 10. In the demodulation circuit 8, the Y
- The chroma signal separated by the C separation circuit 6 is once demodulated based on the color subcarrier signal from the color subcarrier oscillation circuit 3, and R, G, and B signals are reproduced, and these are reproduced by the R, G, and B mixing circuit 9. is supplied to At this time, in the mixing circuit 9, the R, G,
The B signal and the R, G, B signals of different systems supplied to the input terminals 4a, 4b, 4c are mixed, and the added and mixed R, G, B signals are supplied to the chroma signal generation circuit 10. The chroma signal generation circuit 10 generates a chroma signal as shown in FIG. . In the Y-C mixing circuit 11, the Y signal obtained from the Y signal mixing circuit 7 and the chroma signal obtained from the chroma signal generation circuit 10 are mixed, and a signal as shown in FIG. 2 is output to the video output terminal 12. A color composite video signal is derived.

In this manner, in this embodiment, the color composite video signal supplied to the input terminal 1 is once separated into the Y signal component and the chroma signal component, and the chroma signal is further demodulated to reproduce the R, G, and B signals. The Y signal and R, G, B signals are mixed separately with the Y signal and R, G, B signals supplied from another source, and this mixed R, G, B signal is converted back to a chroma signal. After that, it is mixed with the Y signal, and as a result, one color composite video signal in which the two systems of signals are superimposed is derived at the output terminal 12.

<Effects> As described above, according to the signal superimposition device of the present invention,
Rather than directly mixing two systems of color composite video signals, the color composite video signal is first separated into a Y signal component and a chroma signal component, and then this chroma signal is demodulated to reproduce R, G, and B signals. Since the color composite video signal is generated after individually mixing the two systems of Y signal and R, G, and B signals obtained in this way, the Y signal path and chroma signal path after mixing are individually connected as appropriate. By inserting a filter, mutual interference between the Y signal and the chroma signal can be prevented, and cross color interference on the screen almost never appears. Furthermore, in this case, since the two systems of color signal components are mixed, especially in the R, G, and B signals of personal computer data,
It can be superimposed on a color television broadcast received video signal without damaging the high-frequency components peculiar to the computer output signal, and the outline of the computer data superimposed on the screen is clear, with almost no color blurring.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the device of the present invention.
FIG. 2 is a signal waveform diagram for explaining the operation of the same embodiment. 1... Video input terminal, 2... Burst gate circuit, 3... Color subcarrier oscillation circuit, 4a, 4b,
4c...R, G, B input terminal, 5...Y signal generation circuit, 6...Y-C separation circuit, 7...Y signal mixing circuit, 8...Demodulation circuit, 9...R, G, B Mixing circuit, 10...Chroma signal generation circuit, 11...Y-
C mixing circuit, 12...video output terminal.

Claims (1)

[Claims] 1. In a signal superimposition device used in a combination of a color television receiver and a personal computer, which superimposes and displays data from a personal computer on the received image screen of color television broadcasting, the color composite image of the color television receiver is displayed. burst gate means for separating only burst signal components in a signal; color subcarrier oscillation means for oscillating a color subcarrier signal based on the burst signal obtained from the gate means; A Y-C separation means that separates into a signal component and a chroma signal component, and a Y-C separation means that separates the Y-C signal and the R, G, and B signals of data from the personal computer in a separate system. Y-signal mixing means for mixing the chroma signal with the Y signal generated by the Y-C separation means, demodulation means for demodulating the chroma signal separated by the Y-C separation means based on the color subcarrier signal, R, G, B signals that are individually mixed with the R, G, B signals of the data of the personal computer of the separate system
a chroma signal generating means for generating a chroma signal based on the R, G, B signals obtained by the R, G, B mixing means and the color subcarrier signal; and Y-C mixing means for mixing the signal and the chroma signal obtained from the chroma signal generating means, and the apparatus is equipped with a Y-C mixing means for mixing the signal and the chroma signal obtained from the chroma signal generating means, and generates a color composite video signal for superimposing and displaying data from the personal computer on the received video screen of the color television broadcasting. A signal superimposition device characterized in that: