JPS62188480A - Video disk player - Google Patents

Abstract

PURPOSE:To obtain a clear still image by driving a driving means by the 1st control signal to jump a pickup and controlling a memory means by the 2nd control signal to store a video signal immediately before the jump in the memory means. CONSTITUTION:At the end of writing operation in the memory means 9, a control means 22 output a signal (f). A flip flop(FF) 21 reset at the output of the signal (f) inverts its output signal (c) to the low level and a monostable multivibrator 15 is triggered by the inversion and outputs a signal (d). The signal (d) clears an FF 13 and is supplied to a driving circuit 11 to jump the pickup on a point B'. After controlling a CLV disk or the like so as to surely detect one revolution of the disk by a pulse from a rotary pulse generator 12, the pickup is jumped immediately after the completion of storing operation in the memory means 9. Consequently, the time required for storing the video signal in the memory means after jumping it can be maximized, so that a clear image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a video disc player that plays not only a CAV disc with a constant rotational angular velocity but also a CLV disc with a constant linear velocity per rotation.

(Summary of the Invention) In the present invention 1, the reproduction signal from the disk is stored in the storage means based on pulses synchronized with the rotation of the disk, and the pickup is at least Jump one track.

[Conventional technology]

Video signals of a fixed number of fields (e.g. 2 fields or 4 fields) per revolution are recorded on a video disk, and a CAV disk rotates at a constant angular velocity, and as the radius increases, a video signal of a fixed number of fields (e.g. the innermost track) is recorded. A video signal of 2 fields in the outermost track and approximately 6 fields in the outermost track is recorded,
There are CLV disks that are rotated at a constant linear velocity.

With CAV discs, the vertical synchronization signals are aligned on a predetermined radius line, so even if the pickup jumps, the time axis servo will not be disturbed significantly, and it is relatively easy to perform not only normal playback but also special playback such as slow, still, and fast. can be done.

On the other hand, with CLV discs, the vertical synchronization signals are not aligned on a predetermined radius line, so when the pickup jumps, the time axis servo is greatly disturbed, making it relatively difficult to perform special playback such as slow, still, and fast. be. However, by employing the technology disclosed in, for example, Japanese Unexamined Patent Publication No. 58-98881, it is possible to perform special playback operations such as slow, still, and fast even on CLV discs.

[Problem that the invention seeks to solve]

However, in such a conventional device, although the time axis servo is stable and a color image can be obtained, the vertical synchronization signal is discontinuous, making it difficult to see.

[Means for solving problems]

FIG. 1 represents a block diagram of a video disc player of the present invention. In the figure, reference numeral 1 denotes a video disk on which video signals are recorded, and is rotated by a motor 2. As shown in FIG. Reference numeral 3 denotes a light source such as a semiconductor laser. Laser light emitted from the light source 3 is irradiated onto the disk 1 via a beam splitter 4, a tracking mirror 5, and an objective lens 6, and the reflected light is emitted from the objective lens 6 and the tracking mirror. 5
, and returns to the photodetection circuit 7 including the light receiving element via the beam splitter 4. The light source 3, beam splitter 4, tracking mirror 5, objective lens 6, and photodetection circuit 7 constitute a pickup. Reference numeral 8 denotes a demodulation circuit for demodulating the signal from the photodetection circuit 7, and its output is input to the storage means 9. 10
is a synchronization separation circuit that separates and detects the vertical synchronization signal. 1
Reference numeral 1 denotes a drive circuit that drives the tracking mirror 5.

12 is 1 in synchronization with the rotation of disk 1, for example, 1 per rotation.
This is a rotation pulse generation circuit that outputs two rotation pulses.

13 and 14 are flip-flops, and 15 is a mono-multivibrator, and these constitute a generation circuit 16 that generates a control signal for controlling the drive circuit 11 and the storage means 9.

[Effect]

The operation will be explained with reference to FIGS. 2 and 3. A laser beam emitted from a light source 3 is transmitted to a beam splitter 4, a tracking mirror 5. The reflected light is irradiated onto the disk 1 through the objective lens 6, and the reflected light passes through the objective lens 6, the tracking mirror 5, and the beam splitter 4, and returns to the photodetection circuit 7 including the light receiving element. A playback signal containing the recorded video signal can be obtained. This reproduced signal is demodulated by a demodulation circuit 8 and supplied to a storage means 9 and a synchronization separation circuit 10. Further, the tracking error signal generated in the photodetection circuit 7 is supplied to the drive circuit 11, and the tracking mirror 5 is controlled so that the laser beam (pickup) follows a predetermined track.

During normal playback, the demodulated signal from the demodulation circuit 8 is supplied as is to a CRT (not shown) or the like, so that a normal playback image can be obtained.

Next, the operation during the special playback operation will be explained using still operation as an example. Suppose that the pickup (laser beam) is positioned on a track of a CLV disk on which a video signal of 3 or more fields but less than 4 fields per track (one rotation) is recorded, and a still operation command is issued. Thereafter, it is triggered by the pulse b generated from the rotating pulse generating circuit 12 (FIG. 2(b)), and the signal e generated by the output Q of the flip-flop 13 is inverted from a low level to a high level (FIG. 2(e) )). As a result, the clear input is released, and the flip-flop 14 is triggered by the signal a that is output when the synchronization separation circuit 10 first detects a vertical synchronization signal after that time (see FIG.
)), the signal C generated by its output Q is inverted from low level to high level (FIG. 2(C)). When the vertical synchronization signal one field later is detected by the synchronization separation circuit 10, the detection signal a triggers the flip-flop 14, and its output signal C is inverted from high level to low level. The storage means 9 stores one field of demodulated signal input from the demodulation circuit 8 when the signal C is at a high level,
This stored signal is output to a CRT or the like. The mono multivibrator 15 is triggered by the inversion of the signal C from high level to low level, and outputs a pulse d of a predetermined width (
Figure 2(d)). When the pulse d is input, the drive circuit 11
drives the tracking mirror 5 and causes the pickup to jump back to a track one track inside. The pulse d is also input to the clear terminal of the flip-flop 13, the flip-flop 13 is cleared, and its output signal e is inverted from high level to low level. As a result, the flip-flop 14 is not inverted even when triggered by the output a of the sync separation circuit 10, and its output signal C remains at a low level. Then, when the disk 1 rotates once and the pulse b is output again from the rotational pulse generating circuit 12, the same operation as described above is repeated.

The storage means 9 has a capacity of 1 frame (2 fields).
When using the synchronous separator circuit 10,
The frequency-divided signal may be used as a trigger for the flip-flop 14. When playing a video disc on which video signals of 4 fields per revolution are recorded,
A higher quality image can be obtained by setting the capacity of the storage means 9 to one frame rather than one field.

Therefore, as shown by the thick solid line in Fig. 3, the pickup jumps to the inner track by one track at the position of the vertical synchronizing signal B, and passes through the vertical synchronizing signals Y, Z, and A to the vertical synchronizing signal B.
When it reaches the position, the action of jumping again is repeated. The time axis error is large for a while after the jump, and it usually takes from several ms to 10m5 before color lock is performed.
It takes some time. However, what the storage means 9 stores is the video signal of the field immediately before the jump (between the vertical synchronizing signals A and B).

Even if a still operation is performed on the innermost track where two-field video signals are recorded,
A signal in which there is a time margin of at least one field (approximately 16°6 m5) and color lock is completely achieved is stored in the storage means 9.

Therefore, there is no need for time axis correction for one field of the video signal stored in the storage means 9, and a clear still image can be obtained by outputting this signal.

〔Example〕

In the above, the storage means 9 uses the vertical synchronization signal as a trigger.
An embodiment for controlling the drive circuit 11 and the drive circuit 11 has been described. However, the present invention can be implemented without using the vertical synchronization signal as a trigger signal.

Examples thereof will be described below.

FIG. 4 shows an embodiment in which an RS flip-flop 21 is used in place of the T-type flip-flop 14 as the generating circuit 16 in FIG. 1, and a control circuit 22 for controlling writing and reading of the storage means 9 is added. There is.

Pulse b is output from the rotation pulse generation circuit 12 (fifth
(b)), the output signal e of the flip-flop 13 (the fifth
When the clear input of the flip-flop 21 becomes high level and the clear input of the flip-flop 21 is released, the detection signal a (FIG. 5 (a)) from the synchronization separation circuit 10 causes the flip-flop 21 to
is set, and its output signal C (FIG. 5(C)) becomes high level.

When this signal C is input, the control circuit 22 outputs a write signal to the storage means 9, and stores a signal obtained by converting the reproduced signal from the demodulation circuit 8 from an analog signal to a digital signal. In principle, the capacity of the storage means 9 is in units of one field, but it can be made smaller than one field, for example, when combining with other signals at the time of output. In such a case, if the jump of the pickup is waited until the detection signal a is output, the time from the jump to the start of the next write operation will be correspondingly shortened. Therefore, when the writing operation to the storage means 9 is completed, the control means 22 outputs the signal f (FIG. 5(f)). The end of the write operation to the storage means 9 can be easily detected by monitoring its address, for example. It is reset when the signal f is output, and the flip-flop 21 inverts the output signal C to a low level. Triggered by this reversal, the mono multivibrator 15 outputs the signal d (Fig. 5(d)
)). This signal d clears the flip-flop 13 and is supplied to the drive circuit 11, causing the pickup to jump at point B'.

Then, until the next write operation is performed, the control circuit 22 outputs a read signal to the storage means 9 as necessary,
The stored signal is converted back from a digital signal to an analog signal and output. When a vertical synchronization signal is included in the stored video signal, it is possible to prevent the vertical synchronization signal from appearing on the screen by appropriately selecting an address from which to start reading.

FIG. 6 shows an embodiment in which not only the jump timing of the pickup is not synchronized with the vertical synchronizing signal, but also the start of the write operation to the storage means 9 is not synchronized with the vertical synchronizing signal.

In this embodiment, the flip-flop 13 in FIG. 4 is omitted, and the flip-flop 21 is connected to the pulse b (FIG. 7).
b)) is set directly. 7th
As is clear from the timing chart in the figure, the subsequent operation is the same as that in FIG. 4, so detailed description thereof will be omitted.

After making it possible to reliably detect one rotation even in a CLV disk or the like by using the pulses from the rotation pulse generating circuit 12, this pulse is used as a timing reference to determine when to start and end the storage operation in the storage means 9. can be set arbitrarily. It is important that the jump is performed immediately after the storage operation in the storage means 9 is completed so that the video signal can be stored with the time axis error sufficiently stable.

Although the case of still playback has been described above, it is clear that the present invention can also be applied to other special playbacks such as slow and fast playback. The playback direction in these cases can be either reverse or forward by setting the jump direction to the inside or outside of the track. Furthermore, in the above, pulse b
It is assumed that the timing of occurrence of is fixed with respect to the rotation of the disk 1, but for example,
5) Frame-by-frame playback can also be performed by advancing or delaying.

〔effect〕

As described above, the present invention relates to a video disc player that rotates a disc on which a video signal is recorded and reproduces the video signal using a pickup, and includes a rotation pulse generation circuit that generates a rotation pulse synchronized with the rotation of the disc, and a rotation pulse generation circuit that generates a rotation pulse that is synchronized with the rotation of the disc, and a a storage means for storing a signal; a driving means for causing the pickup to jump by at least one track; a first control signal receiving at least the output of the rotational pulse generation circuit as an input and controlling the driving means; and a second control signal for controlling the storage means.
and a generation circuit that generates control signals.

The driving means is driven by the first control signal to cause the pickup to jump, and the storage means is controlled by the second control signal so that the video signal immediately before the jump is stored in the storage means.

The time required to store data in the storage means after jumping can be maximized, and clear images can be obtained even during special playback of CLV discs such as still, slow, fast, and frame advance.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video disc player of the present invention, FIG. 2 is a timing chart thereof, FIG. 3 is a schematic plan view of the disc, FIG. 4 is a block diagram of another embodiment, and FIG. 5 is a block diagram of the video disc player of the present invention. FIG. 6 is a block diagram of another embodiment, and FIG. 7 is a timing chart thereof. DESCRIPTION OF SYMBOLS 1... Video disk 2... Motor 3... Light source 5... Tracking mirror 7... Light detection circuit 8... Demodulation circuit 9... Storage means 10...
Synchronous separation circuit 11... Drive circuit 12... Rotating pulse generation circuit 13.14... Flip-flop 15... Mono multivibrator 16... Generation circuit 21... Flip-flop 22... Control circuit Figure 2 (Task 13) Figure 3 Figure 4 +3 21 15 Figure 5 (f) Figure 6 Figure 7

Claims (1)

[Claims] A video disc player that rotates a disc on which a video signal is recorded and reproduces the video signal with a pickup, comprising: a rotation pulse generation circuit that generates a rotation pulse synchronized with the rotation of the disc; a storage means for storing the video signal, a driving means for causing the pickup to jump by at least one track, a first control signal receiving at least the output of the rotational pulse generating circuit and controlling the driving means; a generation circuit that generates a second control signal for controlling the drive means, the first control signal drives the drive means to jump the pickup, and the second control signal drives the storage means. A video disc player characterized in that the video signal immediately before a jump is stored in the storage means.