JPH0642732B2 - Video disk player - Google Patents

Description

The present invention relates to a servo circuit of a video disk player in which a pickup makes a track jump during special reproduction.

(B) Conventional technology Conventionally, the time axis control in an optical video disc player is stable at a predetermined rotation speed as disclosed in P733 of the magazine "Electronics" (July 1982). In order to eliminate the time-axis fluctuation (fluctuation in reproduced image, color unevenness) caused by unevenness of rotation and eccentricity of the spindle servo and disk for rotating the reading laser beam in the connection direction (direction of rotation of the disk). It consists of a tangential servo for high-speed and high-precision shaking.

The spindle servo compares the reproduction horizontal synchronization signal and the reference horizontal synchronization signal (having a horizontal synchronization frequency) in phase, and drives the disk so that the reproduction horizontal synchronization signal has a regular horizontal synchronization frequency. This is to control the rotation.The Tanzier shalal servo compares the phase of the color burst signal separated from the reproduced video signal with the reference signal, and sends a current according to the generated high-accuracy position error voltage to the tangential mirror. , To oscillate the read laser light in the connection direction. Further, it is also possible to reduce the rotational unevenness of the disk by applying a relatively squeaky fluctuation component of the phase error voltage to the spindle motor.

On the optical video disk, a CA is recorded with a video signal of 2 fields per track at a constant angular velocity.
There are a V disk and a CLV disk in which the linear velocity is recorded at a constant value.

In the CAV disk, the synchronizing signals are arranged in a straight line in the radial direction, and even if the pickup is track-jumped in the radial direction, no discontinuity occurs in the horizontal synchronizing signal. It is a well-known fact that special reproduction is possible.

On the other hand, since the CLV disk has a constant linear velocity, the arrangement of the synchronization signals in the radial direction is random.

(C) Problems to be solved by the invention When track jumping is performed on the above-mentioned CLV disk, a discontinuity occurs in the reproduction synchronizing signal, so that the reproduction horizontal synchronizing signal used for the time axis control becomes discontinuous and the phase control is performed. It will be greatly disturbed. This occurs even for a jump of one track, and once the phase control is disturbed, it takes a long time for the time axis control to stabilize again, and an abnormal control voltage is applied to the spindle motor, resulting in motor performance. Will also deteriorate. This problem will be described in detail with reference to the circuit block diagram of FIG. 3 and the timing chart of FIG.

The reproduction video signal (N) obtained from the pick-up (2) for scanning the CLV disk (1) is passed through the horizontal synchronization separation circuit (3), and the reproduction horizontal synchronization signal (b) is obtained by the oscillation circuit (4). A reference horizontal sync signal (a) (this frequency is the normal horizontal sync frequency) obtained by dividing the created reference clock of 14.31818 MHz by 910 by the reference signal creation counter (5) is compared in phase by the phase comparison circuit (18). Is output as a square wave pulse having a duty ratio according to the phase difference, and this becomes a motor error signal (c). This motor error signal is applied as a motor control voltage to the spindle motor (drive motor) (8) for rotating the disk (1) via the LPF (6) and the amplifier (7).
If the duty ratio of the motor error signal (c) when the motor control is normal is set to 1: 1 in advance,
The sample and hold circuit (10), which will be described later, samples at approximately the center of the triangular wave during sample and hold.

The reference horizontal synchronizing signal (a) is supplied to the triangular wave conversion circuit (9), converted into the triangular wave (d), and input to the sample hold circuit (10). On the other hand, the reproduced burst signal obtained by inputting the reproduced video signal (N) to the burst separation circuit (11) is converted into a square wave by the zero cross in the edge detection circuit (12) and the burst edge pulse creation circuit (13). Sent to. A burst edge pulse (e) output at the zero cross of the reproduced burst signal is created by the burst sampling signal obtained by delaying the reproduced horizontal synchronizing signal (b) in the delay circuit (14).
This burst edge pulse is a sample hold circuit (10)
The triangular wave (d) is sampled.

This hold voltage output (f) is the tangential error signal, and the tangential mirror (16) passes through the amplifier (15).
The deflection angle is controlled and the jitter is corrected. The low-frequency component (relatively slowly varying component) of the hold voltage output (f) is extracted by the LPF (17) and added to the motor control signal (c).

When the time axis control is performed normally in normal playback, the reference horizontal sync signal (a) and the playback horizontal sync signal (b) are shifted by a half cycle, and the duty ratio of the motor control signal is 1: 1. The hold voltage of the sample hold circuit (10) also becomes the central voltage of the triangular wave. If the track jump is performed at the timing (T1), the phase of the reproduced horizontal synchronizing signal (b) becomes discontinuous and the duty ratio deviates greatly from 1: 1.

There is no problem if the reproduced horizontal sync signal is instantaneously pulled into the locked state by the phase difference of 1 / 2H from the reference horizontal sync signal by the motor control, but it takes time to pull in the disk with a large inertia. However, the motor control is disturbed during this period. The same applies to the tangential servo. The above-mentioned phenomenon occurs regardless of the number of tracks for which the track jump is performed.

(D) Means for solving the problems: A disk in which a video signal is recorded at a constant linear velocity, a drive motor for rotating the disk, a playback video signal by scanning the disk, and a track jump jump during special playback. , A reference signal generating means for generating a reference signal having the frequency of the normal horizontal synchronizing signal, and a phase comparison between the reproducing horizontal synchronizing signal and the reference signal in the reproduced video signal, and the phase is determined according to the phase difference. By the phase comparison means for issuing an error signal, the rotation control means for controlling the rotation of the drive motor based on the phase error signal, and the reproduction horizontal synchronizing signal immediately after the track jump of the pickup, the phase of the reference signal becomes zero. And a phase changing means for changing as much as possible.

(E) Action Since the present invention is configured as described above, the reference signal is reset immediately after the track jump, the lock pull-in time of the reproduction horizontal synchronizing signal to the reference signal becomes extremely short, and the disturbance of the time axis control due to the track jump occurs. Can be minimized.

(F) Embodiment One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram of the apparatus of this embodiment, and FIG. 2 is a timing chart. The same parts as those of the conventional example are designated by the same reference numerals and the description thereof will be omitted. Further, this embodiment shows the operation at the time of one track jump.

At the time of track jump, one track jump (A) (B) from the syscon (20) is input to the tracking control circuit (21) and amplified, and then applied to the tracking drive coil (22) to make one track. The jump is executed. Two kinds of tick pulses are required here because the tick pulse (A) is used for jump start and the tick pulse (B) is used for braking.

In the case of one track jump, these two signals are switched at an intermediate point across the track on the disk so that the tracking servo can be stably converged. Therefore, the trailing edge of the tick pulse (A) or the tick pulse ( The front edge of B) is the timing of the intermediate point, and the playback horizontal sync signal switches between before and after the jump, and discontinuity occurs at this point.

An intermediate signal (g) is emitted from the syscon (20) at the intermediate point (T2) (T3) of this track jump, and this intermediate signal
Depending on (g), R-S flip-flop (R-SFF) (2
3) (24) is set. The R-SFF (24) is reset by the first reproduced horizontal synchronizing signal (H1) (H2) that arrives thereafter.

The output (h) of the R-SFF (phase changing means) is a mono-multi (2) having a metastable period of 1 / 2H (H: horizontal scanning period).
5), and the falling edge of the output (i) is detected by the falling edge detection circuit (26). This falling edge detection output (j) resets the R-SFF (23). The output (k) of R-SFF (23) is the reference signal creation counter.
Clear (5). Therefore, the output (k) of the R-SFF (23) is at the H level, that is, the middle point (T) of the track jump.
2) The reference signal is not output during the period from (T3) to the time point delayed by 1 / 2H from the first reproduction horizontal synchronizing signals (H1) and (H2) that arrive thereafter.

The reference signal generating counter (reference signal generating means) (5) is configured to output the reference horizontal synchronizing signal at the same time when the clear is released, and thereafter, continues counting and outputs the reference horizontal synchronizing signal at constant intervals. . Thereafter, the same operation is repeated every time a tick pulse is issued.

The metastable period of the mono-multi (25) is set to 1 / 2H because the phase difference between the playback horizontal sync signal and the reference horizontal sync signal is 1 / 2H when the time axis control is stable. This is because it is set.

As described above, the motor error signal (c) after track jumping
The turbulent period of the tangential error signal (f) is extremely short compared to the conventional example, and if it is such short-term disturbance, the disturbance of the time axis control hardly occurs.

In the multi-track jump, since it traverses multiple tracks during jump, it is detected that the tracking servo has converged after jump, and this signal is detected as the intermediate signal (g) of jump.
The same effect can be obtained by replacing with. Further, in this embodiment, the first reproduction horizontal synchronizing signal (H1) (H2) after the track jump is detected to detect the reference signal generating counter (5).
The reference horizontal sync signal was reset by getting the timing to clear, but due to the difference in the method of time axis control, etc.
It does not necessarily have to be the first.

(G) Effect of the Invention As described above, according to the present invention, it is possible to minimize the disturbance of the time axis control caused by the discontinuity of the reproduction horizontal synchronizing signal when the pickup is track-jumped by the CLV disk. Therefore, trick play on the CLV disk can be realized.

[Brief description of drawings]

1 and 2 relate to an embodiment of the present invention. FIG. 1 is a circuit block diagram, FIG. 2 is a timing chart, FIG. 3 is a conventional circuit block diagram, and FIG. 4 is a conventional example. It is a timing chart. (1) ... Disk, (2) ... Pickup, (5) ... Reference signal creation counter (reference signal generation means), (8) ... Spindle motor (drive motor), (18) ... Phase comparison circuit (phase comparison means) , (23) ... RS flip-flop (phase changing means)

Claims (1)

[Claims] 1. A disc on which a video signal is recorded at a constant linear velocity, a drive motor for rotating the disc, a first kick pulse and a second kick pulse whose leading edge coincides with the trailing edge of the first kick pulse. Jump signal generating means for issuing a jump signal composed of a kick pulse; scanning a disk to extract a reproduced video signal; starting a track jump by the first kick pulse during special reproduction; and braking by the second kick pulse. A pickup for ending the track jump, a reference signal generating means for generating a reference signal having a frequency of a normal horizontal synchronizing signal, a phase comparison between the reproducing horizontal synchronizing signal in the reproduced video signal and the reference signal, and A phase comparison means for issuing a phase error signal according to the phase difference, and controlling the rotation of the drive motor by the phase error signal to re-execute In a video disc player for controlling the time axis of a video signal, the phase relationship between the reproduction horizontal synchronizing signal obtained immediately after the leading edge of the second kick pulse and the reference signal is equal to the phase relationship in the stable state of the time axis control. A video disc player, further comprising phase changing means for changing the phase of the reference signal.