GB2231462A

GB2231462A - Multi-standard compatible video disc player

Info

Publication number: GB2231462A
Application number: GB9003627A
Authority: GB
Inventors: Nobuo Haino
Original assignee: Pioneer Electronic Corp
Current assignee: Pioneer Corp
Priority date: 1989-05-08
Filing date: 1990-02-16
Publication date: 1990-11-14
Anticipated expiration: 2010-02-16
Also published as: GB2231462B; GB9003627D0; JPH02292972A; DE4005658A1; JPH0828856B2; DE4005658C2

Description

:2 3 JL _El 65 -:- Compatible Player for Vieo Discs of Different Systems

The present invention relates to a compatible disc player adapted for playing video discs which are different from each other in the signal format thereof.

Referring first to Fig. 1, a description will be given with regard to a conventional track jump control unit employed in a video disc player designed solely for a disc of NTSC system.

In a block diagram of Fig. 1 showing a known track jump control unit disclosed in U.S. Patent Application No. 230,417 filed October 8, 1988, three beam spots obtained by converging a laser beam, i.e., an information read spot S1 and a pair of tracking information detection spots S2 and S3 preceding and following the spot S1 respectively in the relative motion thereof to the disc, are irradiated from an unshown pickup to a recording 2.

track T on the disc while maintaining the positional relationship illustrated. And the reflected beams of such beam spots from the disc are incident upon photoelectric transducers 1 through 3 incorporated in the pickup.

The phtoelectric transducer 1 comprises four light sensitive elements which are independent of one another and are so disposed that each light receiving surface is divided into four by two mutually orthogonal straight lines, and the total output of such four elements becomes a read RF signal. The read RF signal thus obtained is supplied to a demodulator 13 and is thereby demodulated to a composite video signal. The composite video signal from, the demodulator 13 is supplied to both a decoder 14 and an unsho-wn video output terminal, and simultaneously a vertical synchronizing signal separated from the composite video signal is supplied to a jump pulse generator 8. The decoder 14 serves to decode play control information inserted in, for example, a vertical blanking portion (vertical flyback interval) of the composite video signal, and the decoded information is then supplied to a controller 11.

Meanwhile the outputs of the photoelectric 3 transducers 2 and 3 are supplied to a differential amplifier 4, where the difference between such C,:o outputs is detected to become a tracking error signal which represents the deviation of the information read spot S1 in the radial direction of the disc from the center line of the recording track T.

The tracking error signal is phase-compensated in an equalizer 5 and then is fed via a loop switch 6 to one input terminal of an adder 7. To another input terminal of the adder 7, there is fed a drive pulse (jump pulse) obtained from a jump pulse generator 8. The output of the adder 7 is fed via a low-frequency equalizer 9 to a tracking actuator 10. The lowfrequency equalizer 9 is provided for increasing the gain in a frequency range below the low resonance frequency fo of the tracking actuator 10. In a normal play mode, the tracking actuator 10 deviates the information read spot S1 in the radial direction of the disc either inward or outward by an amount conforming to the polarity and the level of the applied voltage, thereby enabling the spot S1 to accurately follow the center line of the recording track T. A tracking servo loop is formed of the aforementioned circuits 2 through 7, 9 and 10.

The jump pulse generator 8 comprises, as shown 4 in Fig. 6, two monostable multivibrators (hereinafter referred simply to as multivibrators) Ba and 8b supplied with a vertical synchronizing signal, and a pulse generator 8c which generates a drive pulse signal having a duration and an amplitude determined by the controller 11 in accordance with the outputs of the two multivibrators.

The controller 11 consists of a microcomputer for example and, in response to a jump command outputted from a console 12, functions to open the loop switch 6 and controls the jump pulse generator 8 for generating a jump pulse of a duration and an amplitude corresponding to the number of tracks to be jumped. The play control information is used as a reference for controlling such track jump operation.

In the constitution described above, special reproduction is performed in the following manner with execution of track jump in playing a CAV (constant angular velocity) disc shown in Fig. 3.

In the CAV disc, one frame composed of first and second fields is recorded in one track, and synchronizing signals for individual tracks are recorded in the form of a radial array. In the NTSC-system video disc, play control information such as frame number code and so forth are recorded in, for example, 16th to 18th H (horizontal scanning interval) during the vertical blanking period; and other play control information such as picture stop code, chapter number code and so forth are recorded in. for example 279th to 281st II. Meanwhile in the PAL-system video disc, play control information are recorded in 16th to 18th H and 329th to 331st K.

Supposing now that a command for triple speed reproduction is received from the console 12, the controller 11 sequentially drives a spindle servo, a focus servo and a tracking servo which are not shown. After the servos are locked, the demodulator 13 demodulates the read RF signal supplied from the photoelectric transducer 1 and produces a composite video signal of Fig. 4 (A) as an output. And simultaneously a vertical synchronizing signal of Fig. 4 (B) separated from the composite video signal is supplied to the two monostable multivibrators 8a and 8b. The multivibrator 8a generates a high-level output of Fig. 4 (C) in accordance with the fall of the vertical synchronizing signal, and the high level is maintained continuously until the timing of control data. Meanwhile another multivibrator 8b generates a high-level output of Fig. 4 (D) in accordance 6. with the fall of the vertical synchronizing signal, and the high level is maintained continuously until arrival of the next vertical synchronizing signal. If a command for generating a drive pulse is supplied from the controller 11, the pulse generator 8c generates a drive pulse of Fig. 4 (E) in accordance with the fall of the outputs of the two multivibrators. Then the tracking actuator 10 is energized by the positive portion of such drive pulse and is braked by the negative portion thereof. During supply of the drive pulse, the switch 6 is kept open by the controller 11. When such drive pulse is supplied via the adder 7 and the low-frequency equalizer 9 to the tracking actuator 10, a single track jump is caused by the drive pulse, and such single track jump is executed twice in the vertical blanking period to perform a triple speed play. The level of the tracking error signal is also changed in conformity with such track jump, as shown in Fig - 4 (F).

In this manner, the timing to start the track jump is controlled properly to enable special reproduction without harmfully affecting the reproduced image.

The present applicant is now developing a compatible disc player which is capable of playing both of different-system video discs where signals are 1 7 recorded in different formats based respectively on the NTSC system and the PAL system.

When the signal recording formats on video discs are mutually different, the numbers of television image scanning lines become also different so that, in such compatible disc player, it is necessary to automatically discriminate between the signal formats and to selectively switch the setting time of the monostable multivibrator in accordance with the signal format and the content of a special reproduction command.

However, there exist difficulties in accurately and freely setting the time constant of the monostable multivibrator in accordance with the signal format, and some changes are induced in the track jump position during the vertical flyback period due to the timing variation of the multivibrator or the rotational speed variation of the disc, thereby causing faults including dropout of control data or equivalent pulses of the demodulated composite video signal and some disorder in the reproduced image.

It is therefore an object of the present invention to provide a compatible different-system video disc 1 2 player which is capable of playing both of video discs where video signals are recorded in mutually different formats, and still achieving a function to perform an accurate track jumping operation.

In an attempt to accomplish the object mentioned, the compatible video disc player of the present invention comprises a signal format discrimination means for discriminating the signal format of a composite video signal read out from a video disc via a pickup and generating a discrimination signal, a sync signal separation means for separating a vertical svnchronizing signal from the composite video signal, a rotational sync signal generation means for generating a rotational synchronizing signal per predetermined rotation angle of the information recorded disc, an integration means for starting integration of the rotational synchronizing signals in response to each of the vertical synchronizing signals, a comparative reference value setting means for outputting a comparative reference value corresponding to the discrimination signal, a comparison means for generating a detection signal on the basis of the result of comparing the integrated value with the comparative reference value, and a pickup drive means for driving, in response to the z detection signal, the pickup to perform a track jumping operation to jump over the read track.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:- Fig. 1 is a block diagram of a conventional example;

Fig. 2 is a block diagram showing an exemplary circuit constitution of a jump pulse generator 8 in Fig. 1; Fig. 3 illustrates a CAV disc; Figs. 4(A) through 4(F) are timing charts to explain the operation of the jump pulse generator 8; Fig. s is a block diagram of a preferred embodiment according to the present invention; Fig. 6 is a block diagram showing an exemplary circuit constitution of a signal format discriminator 90 in Fig. S; Fig. 7 is a block diagram showing an exemplary circuit constitution of a jump pulse generator 80 in Fig. 5; and Figs. 8(A) through 8(1) are timing charts to explain the operation of the jump pulse generator 80.

10.

Hereinafter a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

In a block diagram of Fig. 1 showing the embodiment of the invention, any components corresponding to those used in Fig. 5 are denoted by the same reference numerals, and a repeated explanation thereof is omitted here.

In Fig. 5, a demodulator 13a demodulates a composite video signal of Fig. 8 (A) from a read RF signal and supplies the demodulated signal to a sync signal separator 13b, a decoder 14 and an unshown video output terminal. The sync signal separator 13b separates a horizontal synchronizing signal of Fig. 8 (C) and a vertical synchronizing signal of Fig. 8 (B) from the composite video signal and then supplies the separated signals to a jump pulse generator 80 and a signal format discriminator 90.

When a CAV disc is played, the horizontal and vertical synchronizing signals are outputted from the sync signal separator 13b in conformity with the rotation angle of the disc. The sync signal separator 13b corresponds to a sync signal separation means and a rotational sync signal generation means.

1 (.

Fig. 6 shows an exemplary circuit constitution of the signal format discriminator 90. This discriminator 90 serves to distinguish between an NTSC signal format and a PAL signal format. The horizontal and vertical synchronizing signals are supplied respectively to an integration input terminal and a reset input terminal of a counter 91. The counter 91 is reset in response to the fall of the vertical synchronizing signal and starts its integration. The integrated value of the counter 91 is supplied to a data latch circuit 92, which holds the integrated value immediately before the reset of the counter and then supplies to a comparator 93 the number of horizontal synchronizing signals existing between vertical synchronizing signals. The comparator 93 compares the integrated value with the value held by the data latch circuit 94 and supplies a signal discrimination output to a controller lla. In the data latch circuit 94, a numerical calue of, for example, 280 is set by the controller lla. In the NTSC format, there are 262.5 scanning lines per field; and in the PAL format, there are 312.5 scanning lines. Therefore, discrimination between such two formats is possible depending on whether the integrated value is greater or smaller than the reference value 280.

1 12.

It is also possible to execute such discrimination by previously inserting a format-representing signal in the control data (play information) for the composite video signal, then decoding such inserted signal by the decoder 14, and supplying the decoded signal to the controller lla to identify the signal format.

Fig. 6 shows an exemplary circuit constitution of the jump pulse generator 80. The horizontal and vertical synchronizing signals are supplied respectively to an integration input terminal and a reset input terminal of an integration counter 81. The horizontal synchronizing signal may include an equivalent pulse in the equivalent-pulse adding portion of the composite video signal. The integrated value of Fig. 8 (D) obtained from the counter 81 is supplied to the comparison input terminals of both comparators 82 and 83. To the comparative reference input terminals of such comparators 82 and 83, there are supplied the comparative reference values individually from the data latch circuits 84 and 85. The comparative reference value held in each data latch circuit is set in conformity with the signal format identified by the controller lla.

The controller lla has, in addition to the known functions of the conventional controller 11, another 1 k 1 13.

-function of setting and controlling desired comparative reference values in the data latch circuits 84, 85 and 92. In comparison with the composite video signal of NTSC system using 525 horizontal scanning lines per frame (262.5 lines per field), the composite video signal of PAL system uses 625 horizontal scanning lines per frame (312.5 lines per field). Therefore a numerical value of, e.g., 280 is initially set in the data latch circuit 94, and the signal format is identified from the output of the comparator 93. And thereafter comparative reference values corresponding to the format of the composite video signal to be demodulated and the content of a special reproduction command are set respectively in the data latch circuits 84 and 85. For example, after an NTSCsystem video disc is placed on a turntable, the number V1 of horizontal synchronizing signals existing from a vertical synchronizing signal to a range between equivalent pulses and control data is set in the data latch circuit 82 in accordance with designation of a triple speed reproduction mode from the console 12. Pleanwhile the number V2 of horizontal synchronizing signals from the vertical synchronizing signal to the horizontal scanning anterior to the next vertical blanking is set in the data latch circuit 83.

14- The comparator 82 compares the inteqrated value with the comparative reference value V1 and Qenerates a first detection signal of Fig. 8 (E) upon coincidence of the two values. The comparator 83 compares the integrated value with the comparative reference value V2 and generates a second detection signal of Fig. 8 (F) upon coincidence of the two values. Thereafter the first and second detection signals are supplied to the pulse generator 8c. The outputs of the comparators 82 and 83 are reset by the vertical synchronizing signal supplied thereto.

In response to the first and second detection signals, the pulse generator 8c generates a drive pulse of Fig. 8 (G) having a duration and an amplitude determined by the controller 11 and then supplies such drive pulse to the adder 7. During supply of the drive pulse, the switch 6 is kept open by the controller lla. When the drive pulse is supplied via the adder 7 and the lowfrequency equalizer 9 to the tracking actuator 10, the actuator 10 is so driven as to cause the information read spot to jump pver the adjacent track. At this moment the tracking error signal outputted from the differential amplifier 4 is such as represented by Fig. 8 (H). The other constitution is the same as that of the circuit R z 1 is shown in Fig. 1.

Thus, the track jump position in the vertical flyback period can be distinguished by counting the horizontal synchronizing signals corresponding to the rotation angle of the disc posterior to supply of the vertical synchronizing signal, so that the jump timing on the time base of the composite video signal can be accurately detected without being harmfully affected by the format difference of the signal recorded on the video disc or by the rotational speed variation of the disc either, hence achieving stable special reproduction.

Fig. 8 (1) represents a drive pulse generated in performing reproduction of a still picture. In a still picture reproduction mode, one track jump is executed in the final scanning portion of a second-field image not displayed on the television screen. For this purpose, the controller lla sets, in one data latch circuit of the jump pulse generator 80, a reference value for the jump position while setting, in the other data latch circuit, a command which inhibits the comparator from generating its output.

In the above embodiment, the horizontal synchronizing signal is utilized as a signal synchronized with the rotation of the disc. However, the same result is t 16 attainable by using the output pulse of a phase-locked oscillator synchronized with the rotation of a spindle motor provided to drive and rotate the disc.

As for the signal-format discrimination means, there may be employed the method proposed by the present applicant in Japanese Patent Application No. 63 (1988)23344 wherein the recorded signal format is identified by discrminating the positional difference in insertion of the control data by the use of a PAL window and an NTSC window; or the method proposed in Japanese Patent Application No. 63 (1988)-12240 wherein the recorded signal format is identified by detecting the presence or absence of an appended signal representative of the signal format. It is further possible to apply the present invention to playing a video disc of SECAM, system as well.

According to the compatible different-system video disc player of the present invention, as described hereinabove, the format of the composite video signal recorded on either of the video discs can be automatically discriminated, then a reference value is selected in conformity with the discriminated signal format and the content of a special reproduction command, and horizontal synchronizing signals or the like obtained correspondingly 1 )7.

to a predetermined rotation angle of the disc are integrated. The integrated value is reset by the vertical synchronizing signal which indicates the reference position on the time base of the composite video signal, and a track jump is started upon attainment of a coincidence between the integrated value and the reference value indicative of the position on the time base of the composite video signal to be jumped. Consequently, satisfactory special reproduction can be performed accurately with regard to both of the video discs having mutually different signal formats.

Claims

CIAIMS:

1. A compatible disc player adapted for video discs of different systems, comprising:

a signal format discrimination means for discriminating the signal format of a composite video signal read out from a video disc via a pickup and generating a discrimination signal; a sync signal separation means for separating a vertical synchronizing signal from the composite video signal; a rotational sync signal generation means for generating a rotational synchronizing signal per predetermined rotation angle of the information recorded disc; an integration means for starting integration of the rotational synchronizing signals in response to each of the vertical synchronizing signals; a comparative reference value setting means for outputting a comparative reference value corresponding to the discrimination signal; a comparison means for generating a detection signal on the basis of the result of comparing the integrated value with the comparative reference value; and i 19.

a pickup drive means for driving, in response to the detection signal, said pickup to perform a track jumping operation to jump over the readtrack.

2. A video disc player according to claim 1, wherein said rotational sync signal generation means consists of a horizontal sync signal separator for separating a horizontal synchronizing signal from said composite video signal and outputting the separated signal as said rotational synchronizing signal.

3. A video disc player according to claim 2, wherein said signal format is based on either the 'l,,',TSC system or the PAL system, and said signal format discrimination means discriminate the signal format by the number of the horizontal synchronizing signals existing between the vertical synchronizing signals.

4. A video disc player according to claim 1, wherein said comparative reference value is set in conformity with the format of the reproduced composite video signal and the number of tracks to be jumped.

5. A video disc player according to claim 1, wherein said signal format discrimination means discriminates the format of the composite video signal on the basis of the identification code extracted from said composite video signal.

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6. A video disc player substantially as hereinbefore described with reference to and as illustrated in figures 5 to 8 of the accompanying drawings.

Published 1990 atThe Patent Office,State House. 6671 High Holborn, London WC1R4TP.Pulther copies maybe obtainedfrom The Patent OffIce. Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd. St Mary Cray, Kent, Con- 1187