JP2697075B2 - Video disc player - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The description will be made in the following order.

A Industrial Fields B Overview of the Invention C Prior Art D Problems to be Solved by the Invention E Means for Solving the Problems (FIG. 1) F Function G Examples (FIGS. 1 to 3) H The present invention relates to a video disc player.

B. Summary of the Invention In the present invention, a TBC does not malfunction by performing a predetermined signal processing following a track jump for scan reproduction at the time of scan reproduction in a video disk player.

C Prior Art First, an example of an optical video disk player will be described with reference to FIGS. 2 and 3. FIG.

In FIG. 2, reference numeral (70) denotes a microcomputer for controlling the operation of the entire player.

Also, (10) shows an optical video disc, on which a signal FM-modulated by a color composite video signal is recorded in a CLV format. And
The disk (10) is rotated by a spindle motor (51) and a spindle servo circuit (50)
Thus, the rotation is servo-controlled so that the linear velocity becomes constant.

Reference numeral (20) denotes a reproducing circuit, and (21) denotes an optical pickup (optical head), which is not shown in the figure, and includes a laser light emitting element, a light receiving element, an objective lens, and an optical axis thereof. It has a tracking coil to control in the radial direction of the
The movement of the disk (10) in the radial direction is controlled by 3).

Further, reference numeral (30) denotes a tracking servo circuit. A part of the output signal of the pickup (21) is supplied to a detection circuit (31) to extract a tracking error voltage Vt, and this voltage Vt is picked up through an amplifier (32). It is supplied to the tracking coil of (21) to perform tracking servo of the objective lens.

Reference numeral (40) denotes a thread servo circuit. The error voltage Vt from the detection circuit (31) is supplied to a low-pass filter (41) to extract a DC component of the voltage Vt. Is supplied to the sled motor (43) through which the sled servo is performed.

Therefore, during normal reproduction, the pickup (21) correctly tracks the track of the disk (10) by the tracking servo circuit (30) and the thread servo circuit (40), and a reproduction signal is obtained from the pickup (21).

The reproduced signal is supplied to an FM demodulation circuit (24) through a reproduction amplifier (22) and a limiter (23) to demodulate a color composite video signal Sc. The video signal Sc is converted to a TBC (25) for time axis correction. ) To remove jitter.

That is, the signal Sc from the demodulation circuit (24) is transmitted to the CCD (25
1), the signal Sc from the CCD (251) is supplied to the synchronization separation circuit (252), and the vertical synchronization pulse PBV and the horizontal synchronization pulse PBH2 are taken out, and the pulse PBH2 is supplied to the phase comparison circuit (253). And the master forming circuit (6
A reference horizontal frequency synchronization pulse REFH is extracted from 1), and this pulse REFH is supplied to a comparison circuit (253).

Then, a phase comparison output of the pulses PBH2 and REFH is taken out from the comparison circuit (253), and this comparison output is supplied to a low-pass filter (254) to change the level according to the phase difference between the pulses PBH2 and REFH. The error voltage TBCE is taken out and the error voltage TBCE is VCO (255)
To the VCO (2
The oscillation signal of 55) is supplied to the CCD (251) as its clock signal.

Therefore, the pulse PBH2 is a signal having a constant phase synchronized with the reference pulse REHF. At this time, the video signal Sc from the CCD (251) is a signal from which jitter has been removed.

Then, the signal Sc is extracted to the output terminal (28) through the memory circuit (26) and further through the amplifier (27).

In this case, although not shown, the memory circuit (26) is used at the time of special reproduction, etc., but an A / D converter for digitizing the input signal Sc and a field where the digitized signal Sc is written It has a memory, a D / A converter that converts the signal Sc read from the memory into an analog signal, and a controller that controls these circuits.
However, during normal reproduction, the memory circuit (26) is bypassed, and the input signal Sc is output as it is.

At this time, the video signal Sc from the demodulation circuit (24) is supplied to the synchronization separation circuit (52) to take out the horizontal synchronization pulse PBH1, and this pulse PBH1 is supplied to the servo circuit (50) and the formation circuit The pulse REFH from (61) is supplied to the servo circuit (50), and the rotation of the motor (51) is controlled so that the pulse PBH1 is synchronized with the pulse REFH, and the above-described spindle servo is performed.

The above is the operation at the time of normal reproduction of the video disc player.

By the way, in the above-described video disk player, the pickup (21) is moved in the radial direction of the disk (10) at a higher speed than during normal reproduction while the tracking servo is applied to the objective lens in the pickup (21). Then, the objective lens tries to stay on the original track while opposing the movement of the pickup (21).

Then, when the pickup (21) moves to the limit of the tracking servo, the objective lens performs a track jump (actually, turns off the tracking servo and forcibly executes the track jump), and again moves the track to which the jump is made. Become tracking.

Therefore, the normal video signal Sc can be intermittently obtained even if the pickup (21) is moved at a higher speed than at the time of normal reproduction.
A fast forward or fast reverse playback screen can be obtained using Sc (hereinafter, such operation modes are referred to as “scan mode”, “scan playback”, etc.).

That is, at the time of scan reproduction, a control signal is supplied from the microcomputer (70) to the amplifier (42) so that the pickup (2
1) is moved in the inner circumferential direction or the outer circumferential direction of the disc (10) at a higher speed than during normal reproduction, and a control signal is supplied from the microcomputer (70) to the detection circuit (31) to cause the pickup (21) to move. A track jump of the objective lens is performed.

Therefore, at this time, the normal video signal Sc is intermittently obtained as described above.

Therefore, the synchronization pulses PBH2 and PVB are output to the memory circuit (26)
Is supplied as a signal indicating the timing of the signal Sc supplied thereto, and a pulse PBV is supplied to the microcomputer (70) as a signal indicating the timing of the signal Sc to form a write request signal WTRQ. WTRQ is supplied to the memory circuit (26).

Further, reference synchronization pulses REFH and REFV of the horizontal frequency and the vertical frequency are extracted from the forming circuit (61), and these pulses REFH and REFV are supplied to the memory circuit (26).

In this way, in the memory circuit (26), when a normal video signal Sc is obtained, one field of w is a pulse PB
H2, written to the field memory in synchronization with PBV, and until the next normal video signal Sc is obtained, the video signal Sc written in the field memory is repeatedly read out in synchronization with the pulses REFH, REFV. Read signal Sc
Is output to the terminal (28).

Therefore, the scan reproduction is performed, and the screen in the middle can be seen at the time of fast forward or fast reverse.

Document: Japanese Patent Application Laid-Open No. 63-95153 and its drawings D Problems to be Solved by the Invention However, when scan reproduction is performed as described above, TBC
(25) malfunctions.

That is, as shown in time t ₁ earlier Figure 3 A through C,
During normal reproduction, the synchronizing pulse REFH criteria are substantially in phase the reproduction synchronization pulses PBH1, PBH2, therefore, as shown in time t ₁ earlier figure E, the time-base error voltage TBCE, the median It is in a state where it slightly fluctuates around Ec according to the jitter.

Then, for scanning the reproduction, when the track jump from the time t ₁ over the time t _2, during this period t ₁ ~t ₂ is
The pulses PBH1 and PBH2 become noise (actually, the CCD (25
Since the jitter compensation is performed in 1), the pulse PBH2 is delayed by about one horizontal period with respect to the pulse PBH1, but this point is ignored.) Further, for example, the filter (254) is controlled by the microcomputer (70), and the error voltage TBCE becomes
A value of ₁ is held from the time t _1.

Then, the track jump is finished at time t _2, when the tracking is stabilized, the next time point t ₃ from the pulse PBH1, PBH2
Can be obtained.

However, when t ₃ when obtained the pulse PBH1 is pulse REFH
Are random with respect to the time point at which is obtained, and generally do not match as shown in FIGS. And both pulses PBH
If the times of 1, PBFH do not match, thereafter, the TBC (25) must perform jitter compensation while always absorbing the phase difference between this pulse PBH1 and REFH, and the TBC (25) has a wide compensation range. It is needed.

Therefore, in this example, when the pulse PBH1 is obtained at time t _3, as shown in the control signal is supplied drawing D to the microcomputer (70) by forming circuit (61), the pulse REFH the time t ₃ To be in phase with the pulse PBH1, and thereafter output every horizontal period as before. Also, bold from time t ₃ TBC (25) is also released.

Therefore, the time t ₃ after, since TBC (25) will be performed time t ₁ as before jitter compensation, then When the vertical synchronizing pulse PBV is obtained, a video signal of one field period following the pulse PVB Sc is written to the memory circuit (26).

However, since the point in time t ₃ is a immediately after the track jump,
If the response of the spindle servo circuit (50) cannot be made in time, for example, immediately after a track jump in the fast reverse direction, the rotation speed of the disk (10) is lower than the rotation speed required at the track jump destination, and Reaches the required rotational speed as time elapses.

Accordingly, when performing for example rewind direction of the track jump, as shown in FIG. B, the synchronization of the synchronizing pulse PBH1, longer than the reference value immediately after time t _3, reaches a reference value as time elapses Will go on.

And a video signal Sc having such a pulse PBH1
TBC (25) for, since the period of the pulse PBH2 from time t ₃ performs compensation operation so that the reference value, the pulse PBH1, P
BH2, the phase relationship of REFH may exceed the coverage of TBC (25), this time, the error voltage TBCE is as shown in the vicinity of time point t ₄ subsequent drawing E, it will stick to the maximum value Eu or minimum value Ed , The TBC (25) cannot operate normally.

And when the TBC (25) malfunctions like this,
Even if the video signal Sc of the next one field is written in the memory circuit (26) just because the synchronization pulse PBV is obtained,
Normal operation cannot be expected.

The present invention is to solve the above problems.

E Means for Solving the Problems Therefore, in the present invention, at the time of scan reproduction, for example, processing such as the flowchart shown in FIG. 1 is performed.

Function F Even if the response of the disk (10) after the track jump is delayed, the TBC (25) operates stably and normal scan reproduction is performed.

G Embodiment In FIG. 1, (100) indicates a scan reproduction routine, which is prepared in the microcomputer (70) and executed at the time of scan reproduction.

In the memory circuit (26), when the write request signal WTRQ is at the "H" level and the synchronization pulse PBV is obtained, thereafter, regardless of the level of the signal WTRQ, the video signal for one field period from the pulse PBV is obtained. It is assumed that Sc is written to the field memory in synchronization with the pulses PBH1 and PBV.

When a fast-forward key or a fast-reverse key (neither is shown) for scan reproduction is pressed, the microcomputer (7
Process 0), starting from step (101) of the routine (100), then in step (102), at time t ₁ T
The error voltage TBCE of BC (25) is held, and then, in step (103), the microcomputer (70) sends the signal to the amplifier (4).
2) and the control signal is supplied to the detection circuit (31) during the period t ₁
~t _2, for example 200 track jump of the track is performed.

Next, in step (104), the error voltage of TBC (25) at time t ₃ when the tracking servo becomes normal TBCE
Is released and the next step (10
In 5), pulse REF from the formation circuit time t ₃ (61)
H is reset, and the pulse REFH becomes in phase with the pulse PBH1 (so far, the same as in the above-described scan reproduction).

Subsequently, in step (106), for example, a time wait of two field periods is performed. This waiting time is a settling period for waiting for further processing until the rotation speed of the disk (10) almost reaches the rotation speed required at the track jump destination, and therefore, the step (106) is completed. the time t _5, the disk (10) is in the rotational speed need.

Next, in step (111), several tracks in the period t ₅ ~t ₆ control signal to the detection circuit (31) is supplied, for example, with a track jump of one track is performed, followed in step (112), the time hold error voltage TBC is released t _6, and are TBCE = Ec.

In this case, the jump number of tracks in step (111) is small, the rotational speed of the disk (10) with its track jump before and track after the jump is substantially equal, the time t ₇ followed time t ₆ (this is the time t Time point t ₃ following ₂
), The tracking servo responds normally and the spindle servo for the disk (10) responds normally. However, the synchronization pulse PBH1
Is similar to the time point t _3, the phase is shifted generally the pulse REFH.

Therefore, in the next step (113), the formation circuit (6
1 pulse REFH at time t ₇ control signals are supplied to) is again reset by the pulse PBH1 in phase, thereafter, be it to a reference pulse for each as expected horizontal period.

The next step (114), wait time until time t ₈ for example 7m seconds is performed. Waiting for this time is TB
Since C (25) may be disturbed, it is for waiting for the subsequent processing until it is stabilized.

Subsequently, in step (115), as shown in FIG. 3 F, write request signal WTRQ at time t ₈ is set to "H" level, then in step (121), the synchronization pulses P
Waiting for BV.

Then, as shown in FIG. 3 G, the sync pulse PBV to some point t ₉ is obtained, in a memory circuit (26),
Video signal Sc for a period in one field from the pulse PBV of the time t ₉ is written in the field memory in synchronism with the pulses PBH2, PBV (this writing, it is only effective scanning period).

In the microcomputer (70), pulse PB at time t ₉
When V is obtained, the process proceeds to step (122), in step (122), for example, the time waiting 5m seconds is performed, then in step (123), the signal at time t ₁₀ WTRQ
Is set to “L” level, and in step (124),
The state is again set to wait for the pulse PBV. Therefore, during the period from step (121) to step (124), the video signal
One field of Sc will be written to the field memory of the memory circuit (26).

Then, when the pulse PBV is obtained again, the process proceeds to step (125). In this step (125), it is checked whether or not the scan reproduction key is pressed. Return from (125) to step (102). Therefore, when the key for scan reproduction is pressed, steps (101) to (101) are performed.
(125) is repeated.

On the other hand, in the memory circuit (26), apart from the writing of the video signal Sc, one field of the video signal Sc is repeatedly read out in synchronization with the reference pulses RPFH and REFV. (27) through the terminal (2
8) is taken out.

Accordingly, scan reproduction is performed as described above.

In step (125), when the key for scan reproduction is not pressed, the process proceeds to step (12).
From 5), proceed to step (126) to execute this routine (100).
, Ie, end the scan reproduction.

Although scan reproduction is performed as described above, in this case, particularly according to the present invention, after the track jump scan playback period t ₁ ~t _2, the period t ₂ ~t ₅ of the spindle servo circuit ( provided with a settling regular 50), since the reset from the time t ₉ the TBC (25) to the time point t ₇ prior to writing the video signal Sc to the memory circuit (26) to TBCE = Ec, point t ₈ REFH, PBH obtained from
Since the phase relationship of 1, PBH2 does not exceed the compensation range of TBC (25), and therefore, the video signal Sc with the correct jitter compensation is supplied to the memory circuit (26).
At the time of scan reproduction, a normal reproduction screen can be obtained.

Further, for the same reason, the compensation range of the TBC (25) can be narrowed, and the cost can be reduced.

Further, when resetting the reference pulse REFH in the step (105), the center point of the eccentricity of the disk (10) is detected, and if this center point is detected, the steps after the step (105) can be executed. If the disk (10)
Since there is no problem even if the eccentricity is large, the cost of the spindle mechanism of the disk (10) can be reduced. Also, in a double-sided player, single-sided chucking can be realized.

Advantages This invention H invention, after the track jump scan playback period t ₁ ~t _2, provided with a settling periodic spindle servo circuit (50) that the period t ₂ ~t _5, point
from t ₉ since the reset TBC (25) to the time point t ₇ Sakidate to write the video signal Sc to the memory circuit (26) to TBCE = Ec, pulse REFH obtained from the time t _8, PBH1, PBH2 of Since the phase relationship does not exceed the compensation range of the TBC (25), the video signal Sc that has been properly compensated for the jitter is supplied to the memory circuit (26). Obtainable.

Further, for the same reason, the compensation range of the TBC (25) can be narrowed, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart of one example of the present invention, and FIGS. 2 and 3 are diagrams for explaining the same. (10) CLV format disc, (20) playback circuit, (30) tracking servo circuit, (40) thread servo circuit, (50) spindle servo circuit, (70)
Is a microcomputer.

Claims (1)

(57) [Claims] An optical head for reproducing a video signal from a video disk, a tracking servo circuit for performing tracking servo of the optical head, and a constant linear velocity of the disk. A spindle servo circuit for controlling, a TBC for correcting the time axis of the reproduced video signal, and a memory circuit, and perform a relatively large track jump of the optical head with respect to the video disk during scan reproduction. When the spindle servo circuit follows the change in the rotation speed of the video disk due to the track jump, the reference horizontal frequency synchronization pulse supplied to the TBC is changed to the horizontal synchronization pulse of the video signal extracted from the TBC. Synchronize with the time error voltage of the above TBC Loaded in the center value, after this set, initially obtained, the video disc one field period of the video signal to be written to the memory circuit from the TBC player.