JPH01276475A - Access system for optical disk - Google Patents

Abstract

PURPOSE:To prevent a seek time from being prolonged by canceling a track servo, loading brake, preventing the flow of a head and executing an access without the recovery processing of a high order device when track leading-in is failed at the time of seeking. CONSTITUTION:While the head is operated, a signal, for which a moire servo signal is caused to be a pulse, is transmitted from a moire detector 7 through a moire control circuit 13 to a processor 15. Then, supervision is continued until the number of moires goes to zero. A moire servo drive instructing signal 14 is turned on and a tracking drive instructing signal 10 is turned off. Here, a deciding signal is transmitted through a tracking leading-in deciding circuit to the processor 15. When the tracking leding-in is failed, the signal 10 is interrupted and zero is set to a velocity data 16. Then, a velocity control servo is canceled and the brake is applied to the head by driving the moire servo. Then, run-away can be prevented. Thus, seek operation goes to be stable and the delay of an access time is not generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to digital optical discs, and particularly to an access method suitable for when tracking pull-in fails in a seek operation.

[Conventional technology]

Conventionally, a signal is used to detect the position of the face controlling the seek side and the position when passing the original disk. This type of signal includes a track servo signal used when a light spot passes a track as a narrow positioning system. Further, as a rough positioning system, there is a moire servo signal when the optical head passes through a linear scale. Based on these signals, speed control is performed according to the optimum speed curve at the target address position l by increasing the number of seeks from the current address position to the target address position It. When the number of seeks reaches zero, the speed 'l'l1lJ control is stopped and the moiré servo is driven. Wait until the relative speed between the original spot and the trunk groove falls below a certain speed (monitor the trunk servo signal, which is all pulsed). Stop the mower 1/sub and drive the tracking servo. Performs track pull-in judgment to check whether they are held on the same track (
Amplitude value monitoring of tracking servo signal). If the track pull-in fails, track pull-in determination is performed until the number of seek arrivals times out. At this time, if the track pull-in determination fails, the head may drift toward the outer periphery, making it impossible to confirm the current address position and having to rely on recovery processing from the host device, which increases access time. A related device of this type is Jikai No. 5B-91556.

[Problem to be solved by the invention]

The above-mentioned conventional technology has a problem in that when a track pull-in fails during seek and the head moves to the outer periphery, recovery is performed by a recovery process from a host device, which increases the access time.

The purpose of the present invention is to release the tracking servo when track pull-in fails during seek, apply a brake to prevent the head from flowing, perform access without recovery processing by the host device, and prevent the seek time from increasing. be.

[Means to solve the problem]

The above objective is achieved by canceling the tracking servo and applying the brake when the track pull-in fails.

[Operation] Tracking servo is canceled when the track pull-in fails.
By issuing an instruction speed of 50 and applying speed control, there is no delay in access time even when the head is flowing.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The optical disc 1 is rotated steadily by a spindle motor 2. A light beam emitted from the laser 21 passes through an optical system and reaches the optical disc 1. As the optical disk rotates, the information track becomes fine (formed) vertically and horizontally. In order to accurately position the light beam on the information track, the autofocus actuator 4 moves the objective lens up and down with 22K gold to focus the light beam. For tracking, a tracking servo signal 24fjc is used as a coarse positioning system to drive the voice coil motor 6 through the entire optical head control circuit 9, and a tracking servo signal 24 is used as a fine positioning system to move the entire optical head 5.
The tracking control circuit 8T - through the galvanometer mirror 5
t-control. In order to enter the seek operation, a tracking servo drive instruction signal 10 is sent from the microprocessor 15.
The tracking servo is turned off (tracking servo is stopped), and target speed data 16 for moving the optical head 3 is generated according to the difference between the target track and the current track.

This is converted into an analog voltage by the D/A converter 17. At this time, the speed control servo drive instruction signal 18't- is turned on.

The moire servo signal is pulsed from the moire detector 7 through the moire Iti II control circuit 15 while the head is moving.
This signal is transmitted to the processor 15, and monitoring is continued until the number of moiré lines reaches l01. 'When the value reaches $1, the speed control servo drive instruction signal 18 is turned off and the moire servo drive signal 14t- is turned on. The tracking servo signal is passed through the comparator 11 and made into a pulse, and the tracking system 12
't-The processor 15 waits until the relative speed between the track groove and the head becomes gentle. Turn on moire servo drive instruction signal 14 and track servo drive instruction signal 1
Let's say 0woo7. 22 is transmitted to the processor through the tracking pull-in determination circuit.

When tracking pull-in fails, the tracking servo drive instruction signal 10 is turned off, the speed data 16 is set to +41, the speed control servo drive instruction 18 is turned on, the speed control servo is canceled, and the moire servo is driven. υ
Since it is possible to apply a brake to the head and prevent it from running out of control, seek operations are stable and there is no delay in access time. Also, Figure 2 shows a 70-chart of the seek system. The difference from the conventional method is that when the tracking pull-in determination is NG, the commanded speed l01 is set and speed control is applied.

〔Effect of the invention〕

According to the present invention, runaway of the head can be prevented and recovery can be made even in the case of tracking pull-in failure, which is effective in stabilizing seek.

4. Easy drawing ii5! FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a macro seek sequence.

1... Optical disk, 7... Moiré detector, 11...
・Comparator, 15...Microprocessor, 14
... Moire servo drive instruction signal, 18... Speed control servo drive instruction signal, 10... Tracking servo drive instruction signal, Atsushi 20

Claims (1)

[Claims] 1. Equipped with a coarse positioning system and a fine positioning system in the head access system, and has means for generating pulses, means for instructing the target movement speed of the head, and means for determining track pull-in according to the amount of movement of the head body. An access method for an optical disk, in an optical disk device, which applies a brake when track pull-in fails to prevent access time delay and head runaway.