JPS6019716B2 - playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION '1) Field of Application of the Invention The present invention provides stable still image playback by synchronizing a reference signal for tracking control and a jump position for still image playback on an optical video disc. This relates to a method for playing back images.

[21 Regarding the tracking control method for optical video discs,
I am familiar with the Tokusei 51-7552 needle blueprint reproducing device, but it is a method that performs tracking control by slightly vibrating a light spot in the circumferential direction of the disk and detecting the phase and amplitude of changes in the amount of reflected laser light. be.

For information on how to play still images from a disk recorded in a spiral manner, please refer to Philips Technic.
al Rev. Vol. 133, 1973, if positive and negative (or negative and positive) pulses are applied to the optical deflector as shown in FIG. 1A, the position of the light spot jumps by one track as shown in FIG. 1B.

Therefore, it is possible to reproduce a still image by adding these positive and negative pulses to the minute vibration signal, or by turning off the tracking servo system, applying positive and negative pulses, and then turning on the servo system again. However, since these positive and negative pulses are generated independently of the reference signal, various situations occur as shown in Figure 2 A and B, and as a result, the size of the jump changes, making it difficult to obtain a stable still image. It becomes impossible to play. {3} Purpose of the Invention The present invention provides, as described above, (by synchronizing the jump signal with the reference signal in order to prevent still image playback from becoming unstable). The purpose is to always perform a jump of one track.

'4- Examples The present invention will now be described in detail with reference to examples.

FIG. 3 shows an outline of an optical video disk reproducing apparatus.

The laser beam emitted from the laser beam 1 passes through a lens 2, a half mirror 3, an optical deflector 4, and an objective lens 5, and is incident on the surface of a disk 6 to a diameter of about 1 micron. The laser beam reflected by the surface of the disk travels backward through the objective lens 5, the optical deflector 4, and the half mirror 3, and is detected by the photodetector 7. In order to track the track recorded on the disk, it is necessary to detect the amount of deviation of the optical spot from the track center position (deviation signal) and move the optical deflector 4 to perform tracking control. One method is to obtain a tracking deviation signal by constantly subjecting the optical deflector 4 to slight vibrations using a reference signal and detecting the phase and amplitude of the reference signal component included in changes in the amount of reflected laser light. Furthermore, in order to reproduce a still image, as shown in FIG. 4, when the disk rotates once and the vertical synchronization signal is reproduced, the light beam must jump outward by one track.

For this purpose, it is necessary to apply positive and negative (or negative and positive) pulses to the optical deflector 4 as shown in FIG. Therefore, during the jump period, the reference signal for the microvibration described above and the pulse for the jump are superimposed. For this reason, if the phase relationship between the reference signal and the jump pulse changes, the voltage will become as shown in Figure 2 A and B, and the amount of movement of the light spot will change, making it impossible to reproduce a stable still image. . Therefore, in order to keep the jump amount constant, it is necessary to synchronize the positions of the reference signal and the jump pulse.

One embodiment for this purpose is shown in FIG. FIG. 6 is a signal waveform diagram. The signal from the reference signal generation circuit 8 is input to the optical deflector drive circuit 9 and the waveform shaping circuit 10, and is input to the optical deflector drive circuit 9 and the waveform shaping circuit 10.
It is shaped into a pulse like this. The reproduced video signal is also input to the synchronization separation circuit 11, which generates a frame pulse having a period twice that of the vertical synchronization signal as shown in FIG. 6B. This signal sets the flip-flop 12, and this output 6th
Input Figure C into the gate circuit 13 to open the gate. The signal from the waveform shaping circuit 10 is input to the gate circuit 13, and the output is the signal shown in FIG. 6D. This is input to the monostable maltapipulator 14 to output a pulse D having a pulse width less than the period of the reference signal, and the falling edge of this signal is used as a jump start pulse. At the same time, the flip-flop 12 is reset by this D signal, and the gate circuit 1
Close gate 3. By changing the pulse width of the monostable maltapipulator 14, the jump start position and the phase of the reference signal can be changed. The reason for changing the phase is that a phase difference occurs between the vibration of the light spot that vibrates minutely and the reference signal due to a delay caused by a mechanical system, etc., and this is adjusted to ensure that the jump is performed. In addition, to create a jump signal as shown in FIG. 1A, the signal from the monostable Maltese piper 14 is passed through the monostable Maltese piperators 15 and 16 to create the signals shown in FIG. 6F and G, and the arithmetic circuit 17, it is possible to create a jump signal as shown in FIG. Therefore, by inputting the output of the arithmetic circuit 17 to the optical deflector drive circuit 9, it is possible to perform a stable jump only once per frame in synchronization with the reference signal. Further, FIG. 7 shows an embodiment in which the pulse width of the jump is equal to the synchronization of the reference signal.

A signal waveform diagram in this case is shown in FIG. The signal from the reference signal generation circuit 8 is waveform-shaped by the waveform shaping circuit 1 as shown in FIG. 8A. The reproduced video signal is input to the synchronization separation circuit 11, which generates frame pulses as shown in FIG. 8B. This signal sets the flip-flop 12 and opens the gate of the gate circuit 13 (FIG. 8C). Gate circuit 13
The signal from the waveform shaping circuit 10 is input to the gate circuit 10, and a flip-flop occurs at the fall of the output of this gate circuit (FIG. 8D).
18 is turned on and off. By resetting the flip-flop 12 at the falling edge of the flip-flop 18, it is possible to generate a pulse synchronized with the reference signal only once per frame, as shown in FIG. 8E. Therefore, the flip-flop 18 is input to the gate circuit 19, and the gate circuit 1
When the signal of output 4 (D) of Figure 8 is gated, the signal of Figure 8F is obtained. Similarly, the signal E of FIG. 8G is obtained by inputting the signal E of the monostable maltapipulator 18 to the gate circuit 21 and gating the signal obtained by inverting the output ○ of the gate circuit 13 by the inverter 20. Therefore, the signals from the gate circuits 19 and 20 are transferred to the arithmetic circuit 17.
A jump signal as shown in FIG. 8 can be generated by inputting the signal to the optical deflector drive circuit 9. '5} Summary As explained above, according to the present invention, in a method of performing tracking control while vibrating a light beam with a reference signal, it is possible to synchronize the jump signal for still image reproduction with the reference signal, and as a result, It is possible to perform stable jumps and to reproduce stable static surfaces.

This method is also effective even when information is continuously read out from signals recorded in a D-circular shape rather than in a spiral.

[Brief explanation of the drawings] Fig. 1A is a jump signal waveform diagram, B is a diagram showing the movement of the track and optical spot, Fig. 2 is a signal waveform diagram with the jump signal added to the reference signal, and Fig. 3 is a diagram of the jump signal waveform. A schematic diagram of a video disc playback system, FIG. 4 is a diagram showing the movement of a light spot on the disc in the case of still image playback, FIG. 5 is an embodiment according to the present invention, and FIG. FIG. 7 is a signal waveform diagram of another embodiment of the present invention, and FIG. 8 is a signal waveform diagram of FIG. 7. */Z diagram Tsutomu 3 diagram Mitsuru 4 diagram *S style fin 5 diagram *Fuzuna 8 diagram

Claims (1)

[Claims] 1. In a device that reproduces a signal recorded on the disk while slightly vibrating a light spot irradiated on the disk so as to cross a track on the disk based on a reference signal, the waveform of the reference signal is shaped. means for adjusting the phase of the shaped waveform;
A reproducing device comprising: means for emitting a signal for jumping the optical spot based on the phase-adjusted waveform; and means for jumping the optical spot based on the jumping signal.