JP2002074866A - Track seek method for optical head of optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the friction of the mechanism of an optical disk device and the variation of torque of a motor, to realize the precision of track seek by the same rough adjustment as that in when attaching a speed sensor, and to significantly reduce the cost of a manufacturing process. SOLUTION: When seeking the track of a disk, the control voltage waveform of track seek is roughly adjusted on the basis of the amount and direction of the number of tracks for fine adjustment track seek. When the direction of fine adjustment track seek and the direction of track seek of the rough adjustment become identical and the number of tracks for fine adjustment track seek exceeds design allowance, a learning gap having one slowdown track is decreased. When the direction of fine adjustment track seek is opposed to the direction of track seek of rough adjustment and the number of tracks for fine adjustment track seek exceeds the design allowance, the learning gap having one slowdown tracks is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track seek for an optical disk drive optical head.
k) an optical disc apparatus which aims at overcoming variations in friction of a mechanism of an optical disc apparatus and torque of a motor by a learning-type track seek method, and improving the precision of the track seek for rough adjustment. This relates to a head track seek method.

[0002]

2. Description of the Related Art A track seek mechanism of an optical disk device is executed by tracking a track on a disk via a laser beam objective lens and by following the objective lens by an optical head.

When seeking a track on a disc, a common practice is performed by two operations. These are 1) moving the optical head to the vicinity of the target track, and 2) causing the laser beam to reach the target track by fine adjustment of the objective lens. The first operation 1) is called a rough adjustment track seek, and the second operation 2) is called a fine adjustment track seek.

In order to improve the precision of rough adjustment,
This is achieved by attaching a speed sensor and performing feedback control. Since the speed sensor is considerably expensive, it does not correspond to cost considerations.

FIG. 1 shows a mechanism of a general optical disk device 1, of which a motor 12 drives an optical head 14 via a gear set or a screw 13. When a seek operation is started, a microprocessor (not shown) outputs a control voltage waveform (see FIG. 2) to drive the optical head 14 to accelerate the optical head 14 from a stationary state to a constant velocity section and then decelerate to a stationary state.

The designer can decide how many tracks (the number of acceleration tracks) the optical head straddles by himself,
Then switch to the maximum speed and operate at a constant speed. Generally speaking, this does not cause any problem (for example, increasing the seek time), but when the number of surplus tracks reaches a predetermined number (the number of decelerating tracks), deceleration is performed and the control voltage is reduced. It is difficult to seek the track smoothly after the completion and to prepare the fine adjustment track seek.

In the case of a mechanism with a small frictional force or a motor with a large torque, there is a problem that the track seek for rough adjustment is over, and in the case of a motor with a large frictional force and a motor with a small torque, the track is roughly adjusted. There is a problem that causes a shortage of seek.

[0008]

The above two situations can all lead to an increase in the number of tracks required for fine-tuned track seeks, ie, often to increase the overall seek time. Therefore, an object of the present invention is to overcome the variation in the friction of the mechanism of the optical disc device and the torque of the motor by the learning type track seek method, and achieve the track seek precision of the rough adjustment similar to the case of attaching the speed sensor. And

[0009]

According to the present invention, when seeking a track on a disk, the control voltage waveform of the track seek is roughly adjusted according to the amount and direction of the number of tracks of the fine adjustment track seek. If the direction of the adjustment track seek and the direction of the rough adjustment track seek are the same and the number of tracks of the fine adjustment track seek exceeds the design tolerance, the number of deceleration tracks is 1
For reducing the two learning gaps, if the direction of the fine adjustment track seek and the direction of the coarse adjustment track seek are opposite and the number of tracks of the fine adjustment track seek exceeds the design tolerance, the deceleration track It is a main object of the present invention to provide a track seek method for an optical head of an optical disk apparatus characterized in that the number of learning gaps increases by one.

Another object of the present invention is to provide a learning type optical head track seeking method characterized in that the number of accelerating tracks, the maximum speed and the number of decelerating tracks are supplied to learning parameters for optimization. Aim.

It is another object of the present invention to provide a learning type optical head track seek method which can significantly reduce the cost in the manufacturing process because it is not necessary to attach a speed sensor to the track seek mechanism of the optical disk device. And

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings to clarify the features and technical contents of the present invention. The present invention is not limited thereto.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a method of seeking a track of an optical head of an optical disk apparatus. In seeking a track on a disk, a coarse adjustment is performed by adjusting the number and the number of tracks of a fine adjustment track seek. This adjusts the voltage waveform of the track seek (see FIG. 3).

As shown in FIG. 3, first, the optical head is moved to the vicinity of the target track (coarse adjustment track seek) (step 31), and then the number of tracks of the fine adjustment track seek is calculated (step 31). 3
2). Then, it is determined whether or not the number of decelerated tracks exceeds a design allowable error of the fine adjustment track seek (step 33).

If not, the work is terminated.
If it is over, it is determined whether the direction of the track seek for the fine adjustment plate and the direction of the track seek for the rough adjustment are the same (step 34).

If the direction of the fine adjustment track seek is the same as the direction of the rough adjustment track seek, the number of decelerating tracks decreases the learning gap by one (step 35). When the direction of the fine adjustment track seek is opposite to the direction of the rough adjustment track seek, one learning gap is increased in the number of decelerated tracks (step 3).
6).

For this reason, when seeking a track on the disk, the apparatus repeatedly learns, and if the number of tracks in the fine adjustment track seek becomes equal to or smaller than the design allowable error, the learning operation stops. When the number of tracks in the fine adjustment track seek exceeds the design allowable error due to a change in temperature, the learning operation starts again during the seek operation.

In the actual case, the number of acceleration tracks and the maximum speed can be added to the learning parameters to determine the optimization.

As described above, the use of the track seek method of the learning type optical head according to the present invention has the following advantages. That is, (1) it is possible to overcome the variation of the friction of the mechanism of the optical disc apparatus and the torque of the motor and realize the track seek precision of the rough adjustment similar to the case of attaching the speed sensor. (2) Since there is no need to attach a speed sensor to the track seek mechanism of the optical disk device, the cost can be significantly reduced in the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a general optical disk device.

FIG. 2 is a waveform diagram of a control voltage in the case of a rough seek track seek.

FIG. 3 is a flowchart in a case where a rough seek track seek is performed according to the amount and direction of the number of tracks of the fine adjustment track seek according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 11 Objective lens 12 Motor 13 Screw 14 Optical head

Claims (4)

[Claims] 1. A track of an optical head in an optical disk apparatus, wherein when seeking a track on a disk, a control voltage waveform of the track seek is roughly adjusted according to the amount and direction of the number of tracks of the fine adjustment track seek. Seek method. 2. The method according to claim 1, wherein the learning parameters for controlling the voltage waveform include the number of acceleration tracks, the maximum speed, and the number of deceleration tracks. 3. When the direction of the fine adjustment track seek is the same as the direction of the rough adjustment track seek, and the number of tracks of the fine adjustment track seek exceeds the design tolerance, the number of deceleration tracks is one. 2. The method according to claim 1, wherein two learning gaps are reduced. 4. When the direction of the fine adjustment track seek is opposite to the direction of the rough adjustment track seek and the number of tracks of the fine adjustment track seek exceeds the design tolerance, the number of deceleration tracks is reduced by one. 2. The method according to claim 1, wherein the learning gap is increased.