JPH0896382A - Optical disk device - Google Patents

Abstract

PURPOSE: To accurately compensate seek error caused by defects existing on a disk and dust deposited thereon by obtaining the seek error after seeking and updating a compensation value. CONSTITUTION: Prior to the start of seeking, light reflected on an optical disk 21 is detected, and a track number being the present position of a spot on the disk is read by a data reproducing detector 10 and a modem 9. Then, the moving distance being the difference between the present track number and a target track number is computed. If the moving track number is zero, the seeking is stopped. If it is not zero, the track number is compared with a prescribed value. When the moving distance is larger than the prescribed value, a compensation value corresponding to the seek distance is added so that the spot is moved to make the moving distance to be zero. After moving, the present position is detected and when the seek distance is more than the prescribed value, the seek distance is compensated. Then, the seek error being the difference between the target track number and the seek error is computed and the newly computed compensation value are stored together with the seek error in a RAM 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device having high seek accuracy.

[0002]

2. Description of the Related Art As a conventional technique, for example, Japanese Patent Laid-Open No. 4-3
There is one disclosed in Japanese Patent No. 05823. That is, in an optical disc device that records and / or reproduces desired information data on a track on the optical disc, when the optical pickup is moved to a predetermined target track by the sled means, it depends on the difference between the target track and the actual arrival track. The error track number is detected, the maximum value and the minimum value of the error track number are cumulatively stored, and when the optical pick-up is newly moved to the predetermined target track by the thread means, the error track number An optical disk device is disclosed in which the average value of the maximum value and the minimum value is added to the target track.

[0003]

The above apparatus records and updates the maximum and minimum values of the error at the end of seek each time it seeks, and seeks the average value of the maximum and minimum values of the error for each seek. Although it is added to the distance to improve the seek accuracy, in so-called direct seek in which the number of spots crossing a track is counted, a seek error is caused by a track miscount, and this track count miss is caused by a media defect or The cause is the attached dust. Since these defects and dust are randomly present on the disk, the track count error increases in proportion to the seek distance, and there is a problem that the seek error cannot be properly corrected depending on the seek distance. Further, when the seek error is normally distributed between the maximum value and the minimum value, the above calculation method may be used, but when the seek error is shifted to one side, there is a problem that it is not properly corrected. further,
Since the disk is rotating during seek, a seek error is generated by the number of rotations of the disk during seek. Although this depends on the rotation direction and the spiral direction of the track formed on the disk, it depends on the seek direction, and in general, too much jump occurs in the outer peripheral direction and insufficient jump occurs in the inner peripheral direction.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical disk device capable of appropriately correcting a seek error caused by a defect existing on a disk or dust adhering to the disk.

[0005]

According to the present invention, in order to achieve the above object, an optical disk apparatus which irradiates a desired track on an optical disk with a spot and reproduces information from the reflected light, present position and object. A moving distance calculating means for calculating a moving distance from the position, a storing means for storing a correction value according to the moving distance, a moving means for moving a spot based on the moving distance and the correction value, and after the seek operation is completed. An optical disk device comprising: an updating unit that calculates an error from a target position and updates the correction value stored in the storage unit. The correction value calculated each time the seek operation is completed is calculated by performing a low-pass operation on the seek error, and the correction value is calculated separately according to the seek direction.

[0006]

According to the optical disk device of the present invention, when the seek operation is performed, the correction value stored in the storage means is added in accordance with the calculated moving distance to move. Further, a seek error is detected after completion of the seek, and the correction value stored in the storage means is updated based on the detected seek error, so that the seek is performed accurately.

[0007]

EXAMPLES The present invention will be specifically described below with reference to examples. FIG. 1 is a schematic explanatory diagram of an optical disk device, in which a host computer 1 and a magneto-optical disk drive device 24 are SCS
Specifically, it is connected to the SCSI controller 4 of the magneto-optical disk drive device 24 by the I-bus 2.

In the control relationship of the magneto-optical disk drive device 24, the SCSI controller 4 is provided with a buffer R.
AM3 is connected, SCSI controller 4 is C
It is connected to PU7. SCSI for the CPU 7
ROM 5 for storing control programs and the like, RAM 8 for storing later-described correction values, etc., error corrector 6 and modulator / demodulator 9
The data reproduction detector 10 and the laser power controller 11 are connected to the modulator / demodulator 9.

The CPU 7 has a tracking servo controller 12, a focusing servo controller 13, and a radial servo controller which perform tracking, focusing, and radial direction control based on various signals output from a servo error detector 25, which will be described later. 14 is connected, and each control is performed via a tracking actuator driver 16, a focusing actuator driver 17, and a linear motor driver 18.

On the other hand, the drive body portion such as the optical head is
Disc motor 22 for rotating the optical disc 21
And an optical head movable part 20 having a disk servo controller 23 for controlling the disk motor 22 and having an objective lens, a driving device and the like below the optical disk 21.
And a bias magnetic circuit 19 for generating a desired magnetic field is arranged above. Further, it has an optical head fixing portion 15 including a semiconductor laser, a light amount detector, and the like which constitute the entire optical head together with the optical head movable portion 20.

Next, the operation of this apparatus will be described. The magneto-optical disk device 24 receives a command from the host computer 1 via the SCSI bus and operates. First, the optical disk 21, which is a recording medium, is rotated at a predetermined rotation speed by the disk motor 22 whose rotation is controlled by the disk servo controller 23. On the other hand, based on the light reflected by the optical disk 21, the servo error detector 25 causes a tracking error signal required for tracking, a focus error signal required for focusing, a lens position signal for tracking, and a tracking error signal for seeking. Is detected. This track error signal is output to the tracking servo controller 12 for tracking control. Also,
The focus error signal is output to the focus servo controller 13 for focusing control.
Further, the lens position signal and the tracking error signal are output to the radial servo controller 14, and predetermined control is performed in the seek operation.

That is, the radial servo controller 1
4 and the linear motor driver 18 make the optical head moving part 2
0 is driven. Further, the tracking servo controller 12 and the tracking actuator driver 16 drive the objective lens inside the optical head moving unit 20. The radial servo controller 14 and the tracking servo controller 12 irradiate a desired position on the optical disk 21 with the laser light emitted from the semiconductor laser. Further, the objective lens is vertically driven by the focus servo controller 13 and the focusing actuator driver 17 so that the laser light applied to the optical disk 21 is focused on the recording / reproducing film. The laser controller 11 controls the amount of light emitted from the semiconductor laser (LD). The laser light whose amount of light is controlled is reflected by the optical disc 21, and a reproduction signal is obtained from the reflected light. The reproduction signal is binarized by the data reproduction detector 10, and the data is demodulated by the modulator / demodulator 9. The demodulated data is corrected by the error corrector 6 if there is an error in the demodulated data,
It is stored in the buffer RAM 3. This data is SC
It is transferred to the host computer 1 via the SI controller 4.

Next, the seek operation of this apparatus will be described with reference to the flow chart of FIG. First, before the seek operation is started, the reflected light from the optical disk 21 is detected, and the number of tracks, which is the current position of the spot on the disk, is read by the data reproduction detector 10 and the modulator / demodulator 9. Then, the moving distance, which is the difference between the current track number and the target track number, is calculated. The number of moving tracks is 0
In the case of, the seek is ended, and in the case of not 0, the magnitude with the predetermined value N is compared. When the movement distance is larger than N, a correction value corresponding to the seek distance is added, and the seek operation, that is, the spot is moved so that the movement distance becomes 0, and the current position is detected after the movement. Here, the seek distance is corrected when the seek distance is equal to or more than the predetermined value N, and the seek distance is not performed when the seek distance is smaller than that because direct seek seeks while counting tracks, so there is almost no seek error in a short distance. is there. Then, the seek error, which is the difference from the target track number, is calculated, and the value and the newly calculated correction value are stored in the RAM 8. Hereinafter, the same operation is repeated.

FIG. 3 shows the allocation of the RAM 8 when the seek distance is divided into 3 blocks. In FIG.
The contents of the RAM (memory) correspond to the addresses as shown in the figure, and symbols A, B, C, etc. in the figure will be described.
A, B, and C are correction values when the seek distance is small, medium, and large, respectively. A1 to a5 are the seek errors of the past five times when the seek error is small, and b1 to b5 are the seek error. 5 seek errors in the past 5 times, c1 to c5 are seek errors in the past 5 times when the seek error is large.

Next, how to obtain the correction values A, B and C will be described with reference to the flow chart of FIG. First, in the first seek, the correction value A is set to 0, the seek distance is moved by the calculated moving distance L, the seek error e1 is obtained after the seek, and a1 = e
1 and A = a1 are stored in the RAM 8. At the time of the second seek operation, A (= a1) is added to the moving distance L,
L + a1 is moved to obtain the seek error e2, and a2 = e2
And the correction value is updated as A = (a1 + a2) / 2. After that, the same operation is repeated until the fifth seek. That is, at the third time, a3 = e3, A = (a1 + a
2 + a3) / 3, a4 = e4, A = (a1 + a) for the fourth time
2 + a3 + a4) / 4, the fifth time is a5 = e5, A = (a
The correction value is sequentially updated as 1 + a2 + a3 + a4 + a5) / 5. From the sixth time, the values are replaced for each seek such as a1 = e6 and a2 = e7, and the average value of the past five times is set as the correction value A and updated.

Another method of updating the correction value will be described with reference to FIGS. 5 and 6. FIG. 5 shows the allocation of the RAM 8, where A, B and C are the same as in the above-mentioned embodiment for each block, that is, the correction values when the seek distance is small, medium and large, respectively.
X1, X2, and X3 are variables for calculating the correction value in each block. Next, the step of calculating the correction value after the seek will be described with reference to FIG. After the seek is finished, the current track number is read, and the seek error e1 is calculated from the difference from the target track. e1, constant α,
Based on the variable x1 stored in the RAM 8, first e2 (= e
1 + α * x1) is calculated. Next, the correction value A is calculated by calculating e2 * β from the previously obtained e2 and β. This e2 is stored in x1 in order to calculate the next correction value. Thereafter, the correction value is calculated in the same manner. In this case, the RAM 8 can be used with a small capacity.

Further, the seek operation direction includes an inner peripheral direction and an outer peripheral direction, and in order to make a more accurate correction, different correction values may be provided in each direction in the above embodiment. In this case, the number of memories assigned to the RAM 8 is twice as large as that in the above embodiment.

[0018]

According to the present invention, since the seek distance, for example, the seek distance is corrected corresponding to each block, it is possible to properly correct the seek error caused by the defect of the disk or the dust attached. In addition, since the correction value is calculated by performing low-pass calculation of the seek error at the end of seek, the number of memories for calculating the correction value need only be the previous calculation result, so the number of memories for averaging calculation is small. Good.
Further, since the correction value of the movement amount is separately provided depending on the seek direction, it is possible to correct the seek error caused by the rotation of the disk.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an optical disk device.

FIG. 2 is a flowchart showing the operation of the optical disk device.

FIG. 3 is an explanatory diagram showing allocation of RAMs according to the first embodiment.

FIG. 4 is a flowchart for obtaining a correction value according to the first embodiment.

FIG. 5 is an explanatory diagram showing allocation of RAMs according to the second embodiment.

FIG. 6 is a flow chart for obtaining a correction value according to the second embodiment.

[Explanation of symbols]

1 ... Host computer 2 ... SCSI bus 3 ... Buffer RAM 4 ... SCSI controller 5 ... ROM 6 ... Error corrector 7 ... CPU 8 ... RAM 9 ... Modulator / demodulator 10 ... Data regenerator 11 ... Laser power controller 12 ... Tracking servo controller 13 Focusing servo controller 14 Radial servo controller 15 Optical head fixed optical section 16 Tracking actuator driver 17 Focusing actuator driver 18 Linear motor driver 19 Bias magnetic field circuit 20 Optical head moving section 21 Optical disk 22 Disk motor 23 … Disk servo controller 24… Magneto-optical disk drive

Claims (3)

[Claims] 1. In an optical disk device for irradiating a desired track on an optical disk with a spot and reproducing information from the reflected light, a moving distance calculating means for calculating a moving distance from a current position and a target position, and this moving distance. The storage means for storing the correction value according to the above, the movement means for moving the spot based on the movement distance and the correction value, and the correction stored in the storage means by calculating the error between the target position after the seek operation is completed. An optical disk device comprising: an updating unit that updates a value. 2. The optical disk device according to claim 1, wherein the correction value calculated each time the seek operation is completed is calculated by performing a low-pass operation on a seek error. 3. The optical disk device according to claim 1, wherein the correction value is calculated separately according to a seek direction.