JPH0463394A - Multipicture display device - Google Patents

Abstract

PURPOSE:To eliminate an influence of jitter of an input video signal by giving the chrominance subcarrier from a PLL circuit to a modulator at the time of selecting the input video signal but giving the chrominance subcarrier from a fixed oscillator to the modulator at the time of selecting an incorporated video signal generating means. CONSTITUTION:Plural switches 19, 19... which are controlled by a fixed oscillator 18 and a microcomputer and select a PLL circuit 16 output or an oscillator 18 output are provided. These switches 19, 19... are interlocked with switches 12, 12..., and when switches 19, 19... select the frame memory 8, 8... output, the switch select a PLL circuit 16 output, when the switch selects a color signal generator 11, 11..., the switch selects the oscillators output and supplies it to modulators 15, 15.... Consequently, modulators modulate the amplitude of the chrominance subcarrier from the oscillator by outputs of color signal generators when a picture subjected to special effect is projected, and therefore, a stable hue is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a multi-screen display device that displays enlarged images and the like using regularly arranged displays.

(B) Conventional Technology A multi-screen display device for obtaining enlarged images has already been proposed by the applicant of the present invention in Japanese Patent Application No. 244292.

This device is shown in FIG. In the figure, (1) is a first input terminal into which a composite video signal is input, (2) is a YC separation circuit that separates this composite video signal into a Y signal (luminance signal) and a color signal (C signal), ( 3) is the second input terminal into which the YC separate video signal is input, and (4) is the YC separation circuit output and the Y signal and C signal from the second input terminal (3) are input respectively, and one is selected. A switching circuit that outputs
(5) converts the C signal into two color difference signals (RY) and (
B-Y) A color demodulator that demodulates the signal, (6) an A/D converter that converts this output into A/D, and (7) a video data bus that distributes the A/D converted video data to multiple devices. , (8)
(8 pieces... are frame memories that each store the same data supplied from this video data bus, (9) is a frame memory that writes and reads information from the input device (10) such as enlargement rate and display position) (11) (11)... is a back color function that outputs a single color regardless of the input video signal; It satisfies special effect functions such as a color wipe function that switches the color and input video signal in the middle of one screen and outputs it, and a coloring function that uses the data of the input video signal for the luminance signal and makes only the color signal a single arbitrary color. color signal generators (12) (12) . . . are controlled by the microcomputer to select the frame memory output or the color signal generator output, a plurality of first switches (13) (13) . . . is a video signal processing circuit that adds vertical and horizontal synchronization signals to the first switch output and clamps the sync chip and pedestal levels;
(14) (14)... is a D/A converter that D/A converts the output of this video signal processing circuit, (15) (15)...
- This D/A conversion output is a signal that matches the input conditions of the display group (not shown), that is, a composite video signal or Y/
This is a modulator that modulates the C-separated signal.

On the other hand, (16) is a PLL circuit that generates a color subcarrier in synchronization with the burst signal in the C signal output of the switching circuit (4) and supplies it to each of the modulators.
)lz VCO, a phase comparator that compares the phases of this VCO output and an input burst signal, and an LPF that smoothes this comparison output and supplies it to the VCO.

Further, (17) is a synchronization separation circuit that separates a synchronization signal from the Y signal of the switching circuit (4), and this output provides a reference phase when adding a synchronization signal in the video signal processing circuit (13). .

Next, the operation of the above circuit will be explained.

First, the switching circuit (4) is switched to the first switch by an external switching signal.
Or the Y signal and C from the second input terminal (1) (3)
Select a signal. Then, the C signal is demodulated into a color difference signal (R-Y) signal and (B-Y) signal by a color demodulator (5),
The A/D-converted video data along with the Y signal is transferred to each frame memory (8) (
8) Supplied to... This frame memory is controlled for writing and reading by a microcomputer (9), and is output as an enlarged video signal with a predetermined enlargement ratio.

The first switch (12) (12)... usually selects the frame memo J (8) (8)... output, and when special effects are used, the color signal generator (11) (11)... output is selected. select. The first switch outputs are further supplied to video signal processing circuits (13), (13), etc., to which a synchronization signal is added and the sync tip and pedestal levels are clamped. Here, since the added synchronization signal is created based on the phase of the output of the synchronization separation circuit (17), the phase of the synchronization signal of the enlarged video signal matches the phase of the synchronization signal of the luminance signal before color demodulation.

Furthermore, each output of the video signal processing circuit is a D/A variable #! After being A/D converted by the devices (14) (14), respectively,
The signal is supplied to the modulators (5), (15), and so on. here,
The color difference signal amplitude modulates the color subcarrier, becomes a composite video signal or a Y/C separated signal, and is supplied to each display (not shown) to display an enlarged image.

Since the color subcarrier generated by the PLL circuit (16) is used as the color subcarrier, the output after modulation matches the phase of the color subcarrier input to the color demodulator (5).

Therefore, if the horizontal frequency and color subcarrier frequency of the input video signal are in an interleaving relationship, the outputs of each of the modulators are also in an interleaving relationship, thereby preventing the occurrence of cross color or dot interference.

Note that the color subcarrier from the PLL circuit (16) is also used by the color demodulator (5).

(c) Problems to be Solved by the Invention By the way, in the above-mentioned conventional circuit, when the input video signal has jitter, that is, when it is a reproduced signal from a VTR or a VDP without time axis correction, When selecting the color signal generator output for special effects, P
Since the color subcarrier from the LL circuit (16) contains sinter, the color signal modulated by the modulator changes hue on the screen, resulting in frill.

The present invention solves the above-mentioned drawbacks, and is capable of maintaining the interleaving relationship between the color subcarrier frequency and the horizontal frequency of the modulated signal when selecting an input video signal, and using a built-in video signal generating means. When selected, a multi-screen display device is provided that is not affected by jitter of an input video signal.

(D) Means for Solving the Problems The present invention provides a video data bus that distributes an input video signal to a plurality of devices, a plurality of video memories to which the same video data is respectively supplied from the video data bus, and the input video data bus. Color subcarrier generation means for generating a signal synchronized with a color subcarrier in a video signal; Video signal generation means for generating a video signal different from the input video signal; and the video memory output or the video signal generation means. a plurality of first switches for selecting an output; a fixed oscillator that oscillates at a color subcarrier frequency;
When the first switch selects the video memory output,
a plurality of second switches that select the fixed oscillator output when the color subcarrier generation means output is selected and the first switch selects the video signal generation means output;
It consists of a plurality of modulation means for modulating the switch output with the first switch output, and a plurality of display means for respectively displaying the output of the modulation means.

(e) Function: By the means described above, when selecting an input video signal, the modulator has P
By providing the color subcarrier from the LL circuit, the interleaving relationship between the modulated color subcarrier frequency and the horizontal frequency is maintained, and when the built-in video signal generation means is selected, the modulator is supplied with the fixed oscillator. Since the color subcarrier is provided, the input video signal is not affected by jitter at all.

Kube) Example An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of the apparatus of this embodiment, and the same parts as those in FIG. 2 are given the same reference numerals and their explanation will be omitted.

The feature of this embodiment is that it is controlled by a fixed oscillator 5 (18) that performs free-run oscillation at the color subcarrier frequency and a microcomputer (9), and is controlled by the PLL circuit (16) output or the fixed oscillator (
18) A plurality of second switches (19) (1
9)... is provided.

This second switch (19) (19)... is linked to the first switch (12) (12)... and this first switch selects the frame memory (8) (8)... output. When the second switch selects the PLL circuit (16) output, and the first switch selects the color signal generator (11) (
11)..., the second switch selects the fixed oscillator output and modulators (15) (15).
Supply to...

Therefore, when displaying an image with special effects, the modulator amplitude-modulates the color subcarrier transmission wave from the fixed oscillator W2 with the output of the color signal generator, thereby eliminating the influence of jitter on the input video signal. A stable hue is reproduced without any interference.

(G) Effects of the Invention As described above, according to the present invention, when selecting an input video signal, the interleaving relationship between the color subcarrier frequency and the horizontal frequency of the modulated signal is maintained, so that in the reproduced image, ,
Image quality deterioration due to cross color or dot interference does not occur, and when the built-in video signal generation means is selected, it is not affected by jitter of the input video signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a multi-screen display device according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional example. (7)...Video data bus, (8)(8)...Frame memory, (11)(11)...Color signal generator, (12)(12)...First switch, ( 15) (1
5)...Modulator, (16)...PLL circuit, (18)...Fixed oscillator, (19) (19)...Second switch.

Claims (1)

[Claims] (1) A video data bus that distributes an input video signal to a plurality of parts; a plurality of video memories each supplied with the same video data from this video data bus; and a video data bus that is synchronized with the color subcarrier in the input video signal. a color subcarrier generation means for generating a signal; a video signal generation means for generating a video signal different from the input video signal; and a plurality of first switches for selecting the video memory output or the video signal generation means output. , a fixed oscillator that oscillates at a color subcarrier frequency; and a fixed oscillator that is interlocked with the first switch, and when the first switch selects the video memory output, selects the output of the color subcarrier generating means, and the first switch a plurality of second switches that select the fixed oscillator output when the video signal generation means output is selected; a plurality of modulation means that modulates the second switch output with the first switch output; A multi-screen display device comprising a plurality of display means for displaying images respectively.