JP2735219B2 - Access method for optical disk device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital optical disk, and more particularly, to an access method of an optical disk device suitable when tracking pull-in fails in a seek operation.

[Conventional technology]

Conventionally, when performing seek control, a signal for detecting a position when passing through a track on an optical disk is used. This kind of signal includes a track servo signal as a thin positioning system when a light spot passes through a track. As a rough positioning system, there is a moire servo signal when the optical head passes through a linear scale. Based on these signals, the number of seeks from the current address position to the target address position is determined, and speed control is performed according to the optimum speed curve from the target address position. When the number of seeks becomes zero, the speed control is stopped and the moiré servo is driven. Wait until the relative speed between the light spot and the track groove becomes lower than a certain speed (monitor the pulse signal of the track servo signal). Stop the moiré servo and drive the tracking servo. A track pull-in determination is performed to check whether the track is held on the same track (monitor the amplitude value of the tracking servo signal). If the track pull-in has failed, the track pull-in determination is performed until the number of times of seeking is excessive. At this time, when the track pull-in determination fails, the head may flow to the outer circumference, the current address position cannot be confirmed, and it is necessary to rely on the recovery processing from the higher-level device, thereby increasing the access time. It should be noted that Japanese Patent Application Laid-Open No. 58-9
There is 1536.

[Problems to be solved by the invention]

The above-mentioned conventional technology fails to pull in the track at the time of seek,
When the head flows to the outer periphery, there is a problem that the access time is increased because the head is recovered by the recovery processing from the host device.

An object of the present invention is to release a tracking servo when a track retraction fails during a seek, apply a brake to prevent a head flow, perform access without a recovery process of a host device, and prevent an increase in seek time. is there.

[Means for solving the problem]

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

[Action]

If the tracking servo is canceled due to the failure of the track pull-in, the designated speed is set to "zero", and the speed is controlled, the access time is not delayed even when the head flows.

〔Example〕

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

The optical disc 1 is normally rotated by a spindle motor 2. The light beam emitted from the laser 21 reaches the optical disk 1 through the optical system. With the rotation of the optical disk, the information track is finely oscillated up, down, left, and right. In order to accurately position the light beam on the information track, the objective lens 22 is moved up and down by the auto focus actuator 4 to narrow the light beam. For tracking, the voice servomotor 6 is driven by the tracking servo signal 24 through the optical head control circuit 9 as a coarse positioning system to move the entire optical head 3. The tracking servo signal 24 is used as a fine positioning system to control the carbano mirror 5 through the tracking control circuit 8. To enter the seek operation, the microprocessor 15
Then, the tracking servo drive instruction signal 10 is turned off (tracking servo is stopped), and the target speed data 16 to which the optical head 3 should be moved according to the difference between the target track and the current track.
Occurs. This is converted by a D / A converter 17 into an analog voltage. At this time, the speed control servo drive instruction signal 18 is turned on. While the head is moving, a signal obtained by pulsing the moiré servo signal from the moiré detector 7 through the moiré control circuit 13 is transmitted to the processor 15, and monitoring is continued until the number of moirés becomes "zero". When it becomes "zero", the speed control servo drive instruction signal 18 is turned off and the moiré servo drive signal 14 is turned on. The tracking servo signal is pulsed through the comparator 11 to obtain the tracking pulse 12, and the processor
At 15, wait until the relative speed between the track groove and the head becomes gentle. The moiré servo drive instruction signal 14 is turned off and the tracking servo drive instruction signal 10 is turned on. 22 is transmitted to the processor through the tracking pull-in determination circuit.
When the tracking pull-in fails, the tracking servo drive instruction signal 10 is turned off, the speed data 16 is set to 'zero', the speed control servo drive instruction 18 is turned on, and when the value becomes 'zero', the speed control servo is released. By driving the moiré servo, the head can be braked and runaway can be prevented, so that the seek operation is stable and there is no delay in access time. FIG. 2 shows a flowchart of the seek system. The difference from the past is the tracking pull-in judgment
NG is to set the indicated speed 'zero' and apply speed control.

〔The invention's effect〕

According to the present invention, runaway of the head can be prevented and recovery can be performed even when tracking pull-in fails, which is effective in seeking stability.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of one 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 moiré servo drive instruction signal, 18 speed control servo drive instruction signal,
10: Tracking servo drive instruction signal, 23: Tracking pull-in determination signal.

Claims (1)

(57) [Claims] 1. A head access system comprising a coarse positioning control system, a fine positioning control system, and a speed control system, and means for generating tracking and moiré pulses according to the amount of movement of a head body, and indicating a target movement speed of the head. An access method for an optical disk device having a means for performing a seek operation and a means for determining a track pull-in; a step of starting a seek operation of the head, and setting a seek direction and a target speed to a means for instructing the movement target speed; Stopping, and starting the speed control based on the instructing means, and setting a new target speed according to the number of remaining seeks by the moiré pulse as a target speed of the speed control system,
Repeating the steps until the remaining number of seeks becomes zero, stopping the speed control when the number of remaining seeks becomes zero, starting the coarse positioning control, monitoring the tracking pulse, and tracking tracking state. Waiting until, stopping the coarse positioning control and starting the fine positioning control; performing a tracking pull-in determination by means of the track pull-in determining means; and Stopping the seek operation, stopping the fine positioning control when the track retraction determination is not performed, and setting a speed zero to the means for instructing the movement target speed, and based on the setting of the speed zero. Starting the speed control, and starting the coarse positioning control in step S2. After the step S2 and the step S1, a predetermined number of times, the access method of an optical disk apparatus characterized by having a step of stopping a seek operation.