JPS58172084A - Reproducing device for color video signal - Google Patents

Abstract

PURPOSE:To prevent jitter from appearing on the output screen of a computer by reducing a phase shift of a signal supplied from the computer to a monitor from a synchronizing signal supplied from a player to the monitor by a specific extent. CONSTITUTION:A signal R-B from the microcomputer 1 is supplied to a switcher 4 through a delay circuit 6 and a control signal SD for the delay time of the circuit 6 is supplied from a player 2 to control the delay time to 0 or 140nsec. Therefore, the delay time of the circuit is 140nsec in a frame period wherein a synchronizing pulse Ps is shifted in phase by 140nsec to hold the phase continuity of a chrominance signal during the variable speed reproduction of the player 2 and 0 in other frame periods, so the signal R-B supplied from the computer 1 to the monitor 5 do not shift in phase by 140nsec from the synchronizing pulse Ps supplied from the player 2 to the monitor 5. Consequently, no jitter appears on the output screen 1 of the computer during the variable speed reproduction of the player 2.

Description

DETAILED DESCRIPTION OF THE INVENTION For example, it is conceivable to use a combination of a microcomputer and a video dice player to guide tourist spots.

That is, in Fig. 1, (1) indicates a microcomputer, and from now on, the standard three primary color signals R, ()
, B are output, and this signal R-B is supplied to the switcher (4). Further, (2) shows, for example, a laser-type video disc player, from which a standard system composite color video signal is taken out, and this signal is supplied to an NTSC decoder (3) k, which is a standard system. The three primary color signals R-B and the composite synchronization pulse P8 are taken out,
These signals R-B are supplied to a switcher (4)K. The switcher (4) is controlled by a control signal sw from the computer (1), and two sets of signals R-B from the computer (1) and the decoder (3) are switched.
Alternatively, the signals are mixed and supplied to the color monitor (5), and the synchronizing pulse Ps from the decoder (3) is supplied to the monitor (5).

Note that at this time, the computer (1) is connected to the player (2).
), a synchronization pulse P, and a color subcarrier S. is supplied to synchronize the video output of the computer (1) and the video output of the player (2).

In this way, by inputting the conditions indicated by the customer into the combiator (1), data such as costs can be obtained;
This is output from the monitor (5) and displayed on the monitor (5)K.

Also, the player (2) is controlled by the computer (1) to play back a screen of the scenery at the destination, and this is displayed on the monitor (5) as an image of the data from the computer (1). For example, they are played back in a superimposed manner.

By combining the computer (1) and the player (2) in this way, various guidance services can be realized.

However, in this case, when the player (2) performs variable speed playback such as slow playback or still playback, the monitor (5)
A jitter of 140 ns occurs on the playback screen due to the following reasons.

That is, in a laser-type video disc, the recording tracks are formed in a spiral shape.

In the standard mode, one frame of the color Eirin signal is recorded in one round. Therefore, in player (2),
During variable-speed playback, for example, during still playback, the scanning position of the playback head (laser light source and light receiving element) is returned by one track each time the video disc rotates once, allowing for still playback in units of one frame. It is carried out. In other words, the still reproduced image is obtained by repeatedly reproducing the color video signal of 1 frame.

However, in the case of the NTSC system, its color subcarrier frequency fs
c is 455 52B m-・□・fv 2 =455
. The phase returns to the original state every two frames (four fields) with respect to the synchronization pulse P8, and is shifted by 1800 for each frame.

Therefore, when performing still playback on the video disc player (2), for example, the reproduced color video signal is a repetition of one frame signal, so the phase of the carrier color signal is as shown in Figure 2. As shown in B, the phase shifts by 180 degrees at the joint between each frame.

Therefore, the video disc player (2) K outputs a synchronization pulse P for each frame during still playback.

The phase of the carrier color signal is shifted by 1800 minutes, that is, 140 nanoseconds, so that the phase of the carrier color signal with respect to the synchronizing pulses P and k becomes the relationship shown in FIG. 2 by 5K.

In other words, during still playback, the temporal position of the synchronization pulse P8 is 140n from the original position in each frame.
The difference is only a second.

Therefore, the monitor (5
), when the video signal from the computer (1) is supplied to the monitor (5), the computer (υ) will have a jitter of 140 ns on the image due to the video signal. will occur.

Similarly, in the case of variable speed playback other than stay playback, the synchronization pulse P8 is generated at a period corresponding to the variable speed playback mode.
Since the phase of 140g is shifted by 1 second, a similar jitter occurs on the output screen of the computer (υ).

This invention attempts to solve these problems.

Let's explain one example below.

In FIG. 3, signals R to B from the computer (1)
is supplied to the switcher (4) through the delay circuit (6), and a control signal Sd for the delay time of the delay circuit (6) is supplied from the player (2), and the delay time is controlled to 0 or 140 ns. . This signal 8d is a signal that controls the track position of the playback head during variable speed playback of a video disc, that is, a signal that returns the playback head to the original track when the video disc has completed one rotation in the case of still playback. This is the same signal that indicates whether or not the synchronization pulse P8 has been shifted by 140 ns, and the frame period in which the sync pulse P8 is delayed by 140 ns as described above, The delay time of the delay circuit (6) is controlled to 140 ns.

According to such a configuration, in order to maintain the continuity of the phase of the carrier color signal during variable speed playback of the player (player), during the frame period in which the phase of the synchronizing pulse P8 is shifted by 140 ns, the signal 8 dK is The delay circuit (6) has a delay time of 1
40 ns, and the delay time is 0 during other frame periods.
Therefore, the signal R-B supplied from the computer (1) to the monitor (5) via the switcher (4) is the synchronizing pulse P, which is supplied from the player (2) to the monitor (5) via the decoder (3). The difference of 140 ns with respect to the 140 ns disappears.

Therefore, when the player (2) performs variable speed playback, the computer (
1) No jitter occurs on the output screen.

FIG. 4 shows an example of the delay circuit (6). That is, Ql
* Qg is an emitter follower transistor for buffering, (6D) is an LC delay circuit with a delay time of 140 ns, and (6W) is a switch circuit. The delay time of this delay circuit (6) is controlled to 0 or 140 ns.

In the example shown in FIG. 5, the synchronization pulse P6 from the computer (1) is supplied to a delay circuit (6S) which is controlled similarly to the delay circuit (6), and its output is supplied to the monitor (5). This is the case.

In the example shown in FIG. 6, the composite color video signal from the player (2) is supplied to the synchronization separation circuit (7) and the synchronization pulse P is extracted, and the pulse Ps from the computer (1) is Synchronization pulse P8 and phase comparison circuit (
8), the phase is compared and the comparison output is the signal S4.
When there is a phase difference between both synchronizing pulses pB, the delay circuit (6) performs a delay.

In the above description, the computer (1) may be one that outputs a standard color television signal, such as a color video camera.

[Brief explanation of the drawing]

1, 2, and 4 are diagrams for explaining this invention, and FIGS. 3, 5, and 6 are system diagrams of an example of this invention. (1) is a microcomputer, (2) is a video disc player, (4) is a switcher, (5) is a monitor, (
6R) to (6B) are delay circuits.

Claims (1)

[Claims] A video playback device that is externally synchronized and capable of variable-speed playback, and that corrects the phase of the synchronization pulse to ensure continuity of the carrier color signal during variable-speed playback, and a color television signal that serves as a reference. Using the output Eirin equipment, the synchronization pulse and color subcarrier of the reference color television signal were supplied to the video playback device as an external synchronization input to apply external synchronization, and the phase of the synchronization pulse was corrected. A signal indicating that the phase of the reference color television signal is changed by the amount of correction of the phase of the synchronization pulse, and the color television signal whose phase has been changed is switched between the color television signal whose phase has been changed and the reproduction output of the video reproduction device. A playback device for color video signals that is mixed and supplied to a color monitor for display.