JPH01264663A - information reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for performing random access of a long-duration disc in an information reproducing apparatus such as an optical video disc player at high speed.

[Conventional technology]

Conventional devices count the number of times the pickup crosses a track and use this as control information for moving the pickup to a target track on the disk.

[Problem to be solved by the invention]

The conventional technology focuses only on moving the pickup, and does not consider servo locking of disk rotation. Therefore, in a disk where signals are recorded at a constant linear velocity and the number of rotations must be changed between the inner and outer circumferences of the disk (long-term CLV disks), even if the pickup is moved by track count, the disk rotation Because it takes time for the servo to lock, it took a long time to start playback.

An object of the present invention is to move the pickup and start playback of a long-duration disc at high speed.

[Means to solve the problem]

The above object can be achieved by relating the number of rotations of the disk to the movement of the pickup. That is, since the number of revolutions of the disc can be calculated based on the desired position for reproduction, the number of revolutions of the disc is first set to a predetermined number, and then the pickup is moved. At this time, if you use the synchronization signal recorded on the disk instead of the track count to move the big amplifier, the movement end position can be set to the synchronization signal or a predetermined width, so it takes time to servo lock the disk rotation. is not required.

[Effect]

The disk motor servo circuit controls the disk motor at an accurate rotation speed using a synchronization signal from the disk. Since this circuit performs accurate control, rapid changes in rotational speed cannot be controlled.

The predetermined rotation speed setting circuit rotates the disk motor to an arbitrary rotation speed, such as 1000 τpm. Since this control does not require accuracy, it is possible to change the rotation speed rapidly.

・　3　・ 〔Example〕 Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The figure is a block diagram showing a disc motor drive section and a recording signal reading section of an optical video disc as an embodiment of the present invention. Two synchronization signals, a vertical synchronization signal and a horizontal synchronization signal, are recorded on the long-duration disk 4.
Either one is used to move pickup 3. On disk 4 for a long time.

A signal is recorded so that the reading light beam from the pickup 3 scans the disk for a fixed length per unit time, so when the pickup 3 is at the inner circumference of the disk, the rotation speed is increased and the pickup speed is increased. 3 is on the outer periphery of the disk, the rotation speed must be slowed down.

During normal playback, the signal from the pickup 5 is demodulated by the demodulation circuit 8, and the synchronization signal contained therein is sent to the disk motor servo circuit 5.

In step 5, the disc motor 1 is controlled so that the width of the synchronizing signal becomes a specified value. At this time, the switch 11 is connected to the A side.

4. During random access, the movement of the pickup 3 and the number of revolutions of the disk 40 must be controlled at the same time. The amount of movement (9 rotations) at this time can be calculated from the recording width of the disk and the length of scanning the disk within a unit time. The rotation speed at the target position is calculated, and the predetermined rotation speed setting circuit 6 rotates the disk motor 1 to this rotation speed. At this time, the switch 11 is switched to the B side. Next, the comparison circuit 9 sends a control signal to the pickup motor drive circuit 7 based on the time difference between the synchronization signal from the demodulation circuit 8 and the reference time generator 10 . The pickup motor 2 is rotated by a drive signal from 7 to move the pickup 6. Furthermore, when the time difference between 8 and 10 disappears, the comparison circuit 9 switches the switch 11 to the A side, and the pickup motor drive circuit 7
send a stop signal to

When the movement of the pickup is completed as described above, the rotation speed of the disk motor is normal, so that no time is required for the disk motor servo circuit 5 to servo lock.

〔Effect of the invention〕

According to the present invention, in the conventional long-duration random access to a disk, it was necessary to move the 11 pick-up in a servo-locked state of the disk motor, so the movement speed was limited. According to the present invention, since the movement of the pickup and the servo lock of the disk motor are performed in a short time, it is possible to improve the speed of random access.

[Brief explanation of the drawing]

The figure is a block diagram of one embodiment of the present invention. 1......Disc motor 2...
・・・・・・Pink up motor 6・・・・・・・・・
...Pickup 4...Long time disk 5...Tiff motor servo circuit 6...・Predetermined rotation speed setting circuit 7・・・・・・・・・Pickup motor drive circuit 8・・・・・・・・・Demodulation circuit 9・
......Comparison circuit・7

Claims (1)

[Scope of Claims] 1. In an information reproducing device from a disc that requires rotation at a constant linear velocity when reproducing recorded information, there is provided a drive means 1 for rotationally driving the disc 4, and a drive means 1 for driving the disc 4 to rotate there; A scanning means 3 that scans the disk surface to reproduce recorded information, and a demodulating means 8 that demodulates the reproduced signal from the scanning means 3 and extracts a synchronization signal.
and a rotation speed control means 5 which receives the synchronization signal from the demodulation means 8 and controls the drive means 1 so that the time width of the synchronization signal becomes a predetermined width. a predetermined rotation speed setting means 6 for setting a predetermined rotation speed of the disk 4 at a target position on the disk 4 to be accessed when the means 3 performs random access on the disk 4; At this time, the connection circuit from the rotation speed control means 5 to the drive means 1 is switched to the connection circuit from the predetermined rotation speed setting means 6 to the drive means 1, so that the disk 4 is rotated at a specified rotation speed at the target position. a switching means 11 for moving the scanning means 3 on the disk 4, a reference time generation means 10, a synchronization signal from the demodulation means 8 and a reference time width from the reference time generation means 10. and a comparing means 9 for comparing the time width of the synchronizing signal and the reference time width, and controlling the moving means 2 and the scanning means 3 so that the comparison result in the comparing means 9 becomes zero. Information reproduction characterized in that it further comprises a movement control means 7 for moving the information on the disk 4, and a means for returning the switching means 11 to its original state when the comparison result in the comparison means 9 becomes zero. Device.