KR0150818B1 - Method for compensating track servo coefficient upon accessing track on optical disk - Google Patents

Abstract

The present invention relates to a servo coefficient correction method for moving a disc track, wherein the track servo control method of an optical disc performs track movement by calculating a track error from a current track position to a target track according to a track jump command. Determining the direction of movement to the target track according to the track jump command, and subtracting the current track position from the target track position when moving the track in the determined movement direction to calculate the error value of the current track for the target track and based on the calculated error value. According to the result obtained by multiplying the number of blocks / tracks existing in the inner track and the outer track by the number of moving tracks set to a certain number of tracks, it is divided into sections from N or more until the first to fifth sections. Determine the track servo coefficient correction optimized step by step so that the target track can be moved in a short time. It is.

Description

Track Servo Factor Correction Method when Moving the Track of Optical Disc

1 is a block diagram showing a servo system of an optical disc reproducing system for implementing a track servo coefficient correction method when moving tracks of an optical disc according to the present invention.

2 is a flowchart for explaining a track servo coefficient correction method for moving tracks of an optical disc according to the present invention.

3A and 3B are diagrams for explaining the method of determining the inner and outer track numbers of optical discs and their correction coefficients applied to the servo coefficient correction method when the track of the optical disc moves according to the present invention.

* Explanation of symbols for main parts of the drawings

10: optical disc 20: control unit

30: spindle motor drive part 40: spindle motor

50: optical pickup device 60: RF amplifier

70: track error calculation unit 80: servo coefficient correction table

90: track error correction part 100: amplification part

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a track servo coefficient correction method for moving tracks of an optical disc, and more particularly, to linear speed (CLV) for inner and outer tracks of an optical disc, which is performed when a track jump is performed to reproduce information on an optical disc. The present invention relates to a method for correcting a track servo coefficient when moving a track of an optical disc capable of searching a target track for a short time by correcting a track servo coefficient for an inner track and an outer track during servo control.

Currently, a linear speed servo control is performed for a compact disc for audio or a compact disc for recording audio / video information, which is known as an information storage medium capable of random reproduction of information at an arbitrary position. Normal information can be reproduced only when the information reproducing process is performed while the inner and outer tracks are rotated at a constant speed appropriately at all times. As is well known, an optical disc as the information storage medium is a lead-in area in which management information (TOC information or lead-in information) including a track number for the disc or starting and ending addresses of the track is recorded. And a lead-out area in which actual information is recorded and a lead-out area indicating the end of the program area of the disc, and the optical disc has various dimensions (for example, 8 cm, 12 in manufacturing form). Cm, 20 cm, and 30 cm in diameter).

In an optical disk reproducing system that handles such disk-shaped information storage media, the laser beam is irradiated from the optical pickup apparatus in a state where the optical disk as the information storage media is rotated at a constant speed, and the reflected light corresponding to the information recorded on the information recording surface of the optical disk. Information is reproduced based on the presence or absence.

Therefore, the optical disc reproducing system performs the servo control of the optimized disk when the information is read on the same track on the information recording surface or when the target track is changed in accordance with the track jump from the inner track to the outer track or vice versa. The tracking / focusing servo is performed to control the position of the optical pickup device with respect to the spindle servo and the target track.

That is, for an inner track recorded in a relatively dense form of information tracks on such an optical disc, the rotational speed of the optical disc is controlled at a low speed during the servo operation by linear speed control, while the information on the outer track recorded in a distributed form is relatively low. In the servo operation by the linear speed control, the rotation speed of the optical disk is controlled to be substantially high so as to reproduce the information recorded on the inner track and the outer track.

By the way, when a track moving command for reproducing information at an arbitrary position is input and a moving command for a target track is provided to the servo control system from the control means for controlling the servo control in the optical disc reproducing system, the servo control system currently The track error number for the target track is calculated based on the position (i.e., track information) detected from the rotational speed of the disk by the spindle motor of the disk and the position information on the target track provided by the control means. The optical pickup device is transported to search for a target track.

Typically, the pitch between adjacent tracks defined on an optical disc is approximately 1.6 [mu] m. In track search, an error value of the current track for a target track is generally calculated based on the pitch between the adjacent tracks. Due to the manufacturing process, tolerance, and spindle servo error, it is somewhat variable, which increases the possibility of error in track search.

The error associated with such a track search is not a big problem in a compact disc playback system that exclusively deals with compact discs in which only audio signals are recorded, but the video / audio information is compressed by the MPEG algorithm. In the case of video compact discs recorded in the recording format, the playback quality is a significant disadvantage. That is, when the information recorded on the video compact disc is processed by a slow motion picture function or when the information of a specific position is scanned, a continuous one-track jump operation is performed. If the high-speed search is not performed, the playback screen is unnatural. Therefore, since the disc servo method applied to the track search in the related art is performed without properly considering the number of frames (or blocks) / tracks of the inner and outer tracks, the exact target track position is searched. This is a difficult situation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances of the prior art, and when a track is searched on an optical disk as an information storage medium, the track movement is calculated by calculating a predetermined track servo correction value based on the number of tracks in advance for the inner and outer tracks of the optical disk. It is an object of the present invention to provide a track servo coefficient correction method for moving tracks of an optical disc which enables accurate and fast track movement by applying the correction value according to the direction.

In order to achieve the above object, according to a preferred example of the present invention, in the track servo control method of an optical disc, track movement is performed by calculating a track error from a current track position to a target track according to a track jump command. Determines the direction of movement to the target track according to the track jump command for the track, subtracts the current track position from the target track position when the track moves to the determined movement direction, and calculates the error value of the current track for the target track. Based on the result obtained by multiplying the number of blocks / tracks existing in the inner track and the outer track by the number of moving tracks set to a predetermined number of tracks, it is divided into sections from N or more until the first to fifth sections or more. Step by step to determine the optimized track servo coefficient correction so that the movement of the target track can be performed in a short time. The track is a servo track movement coefficient correction method of the optical disc, it characterized in that there is provided.

Preferably, the track servo coefficient corrections, which are divided into steps from the time of N or more to the time of the first to the fifth time and are optimized step by step, are 128 tracks, 64 tracks, 16 tracks, 8 tracks, 4 tracks, and 1 track, respectively. Corresponding to the difference of minutes Df, the moving track number is set to gradually decrease as the track error for the target track number approaches.

Therefore, according to the track servo coefficient correction method for moving a track of an optical disc according to the present invention, the moving direction to the target track is determined according to the track moving command for the target track, and thus the determined moving direction, i.e., to the inner track and the outer track. Since the movement is determined, the track value of the current track for the target track is calculated, the track servo correction coefficient is determined based on the calculated error value, and the servo is moved for the track movement. Can be done.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

1 is a block diagram of an apparatus for implementing a servo coefficient correction method for moving a disc track according to the present invention. Reference numeral 10 denotes a compact disc on which audio information is recorded or audio / video information by a predetermined algorithm (MPEG algorithm). An optical disc as an information storage medium such as a video compact disc that is compressed and recorded, and 20 indicates a constant speed rotation with respect to the optical disc 10 when a track jump command for reproducing information recorded at an arbitrary position of the optical disc 10 is input. A control unit outputs a motor control signal for driving and target track information (Tt) for the disk 10, and 30 denotes a constant speed of the spindle motor 40 based on the motor control signal provided from the control unit 20. The spindle motor driving unit allows the disk 10 to be driven to rotate at a constant rotational speed by driving.

In addition, 50 is an optical pickup device for reproducing information recorded at an arbitrary position of the disc 10. The optical pickup device 50, as is well known, uses an electric motor such as a sled motor. It is moved in the horizontal direction with respect to the optical disk 10 by an optical pickup transfer mechanism, which includes a laser beam on the information recording surface of the optical disk 10, and receives the reflected light reflected from the information recording surface of the optical disk 10. RF signal is reproduced.

60 denotes an RF amplifier for amplifying the RF signal read out at an arbitrary position of the optical disc 10 by the optical pickup device 50, and 70 denotes a current track position based on the rotation speed of the spindle motor 40. FIG. And a track error calculation unit for calculating a track error Te based on the determined current track Tc and the target track Tt according to the track jump command provided by the controller 20. The track error Te is calculated by subtracting the current track Tc from the target track Tt.

80 is a servo coefficient correction table in which servo coefficient correction data for the track error Te detected by the track error calculation unit 70 is tabled and stored, and is formed on the optical disc 10 as described above. In order to minimize a state in which pitch between adjacent tracks is accompanied by errors or tolerances in manufacturing process and spindle servo error, servo coefficient correction values existing in the inner and outer tracks of the optical disk 10 are stored in a table. According to the track servo coefficient correction method when the track of the optical disk of the present invention is moved, the servo coefficient correction value (ba) tabled in the servo coefficient table (90) is the total for the optical disk (10) when considering the optical disk having a diameter of 12 cm. The following equation based on the reproduction time (T) and the circumference distance (r),

Is determined from the correction table shown in FIG. 3 (a) and the correction graph of FIG. 3 (b) created by the correction table.

That is, the correction table shown in FIG. 3 (a) blocks blocks for each track based on the entire play time (unit: min) when the track moves from the inner track to the outer track of the optical disc 10. FIG. In order to minimize the error for the inner track and the outer track when the track movement is calculated by calculating the number of tracks in advance, for example, 15 blocks / track are defined in the innermost track (that is, play time = 0 min). 25 blocks / track are defined for the outermost track (i.e., playback time = 70min), and from such a result, the graph shown in FIG.

90 multiplies the track error Te calculated by the track error calculation unit 70 and the servo coefficient correction value ba for the track error provided by the servo coefficient correction table 80 to the target track. A track error correction unit for generating a track error correction signal for movement is shown. 100 denotes an optical signal for moving the optical pickup device 50 to a target track by amplifying the track error correction signal generated by the track error correction unit 90. Pick-up transfer mechanism, in particular, an amplification part applied to the sled motor.

Next, a servo coefficient correction method for moving a disk track according to the present invention will be described in detail with reference to the flowchart shown in FIG.

First, the present invention is effectively applied when correcting a track error of about 400 tracks. The spindle motor 40 is driven by the spindle motor driver 30 under the control of the control unit 20. The track jump command is controlled from the outside while the optical pickup device 50 reproduces the information recorded at an arbitrary position of the optical disc 10 as the RF signal amplified by the RF amplifier 60 while When applied to (20), the control unit 20 outputs the information of the target track Tt corresponding to the track jump command and applies it to the track error calculation unit 70.

The track error calculation unit 70 calculates a track Tc corresponding to the current position based on the rotation speed detected by the spindle motor 40, and then the target track provided by the controller 20 in step 120. The current track Tc is subtracted from the Tt to determine the moving direction of the optical pickup device 50 (that is, the inner track direction or the outer track direction), and the track error Te is calculated. The track error Te thus calculated is applied to the track error correction unit 90. At this time, the controller 20 controls the servo of FIG. 3 a stored in the servo coefficient correction table 80 based on the track error Te calculated by the track error calculator 70 in step 122. With reference to the coefficient correction table, it is determined whether the track error Te exhibits a difference Df of, for example, 128 tracks or more from the current track position. In determining the difference Df, for example, when the current track position is about 10 minutes in terms of playback time and the absolute time for the target track is 16 minutes, the track error calculation unit 70 The calculated track error Te is determined by multiplying the servo coefficient correction value ba (ie 17 blocks / track) of the servo coefficient correction table 80 of FIG. 3 by 128 tracks. If the difference Df is greater than or equal to 128 tracks, i.e., greater than or equal to N, the track error correction unit 90 moves 128 tracks to optimize the target track. The track error correction signal for the output to the amplifier 100. Accordingly, the amplification unit 100 amplifies the track error correction signal for the movement of 128 tracks and applies the same to the sled motor constituting the optical pickup transfer mechanism so that the optical pickup device 50 receives the 128 tracks on the disc 10. The movement of minutes is done.

On the other hand, if the difference Df of the track of the current position with respect to the target track does not represent a difference of 128 minutes, the determination in step 122 determines whether the difference Df is about 64 tracks in step 124. If the difference Df is 64 tracks or more, that is, the first section or more, as described above, the track error correction unit 90 optimizes the movement to the target track. By applying the track error correction signal for the movement of 64 tracks to the sled motor constituting the optical pickup transfer mechanism through the amplifying unit 100, the optical pickup device 50 causes the 64 tracks on the disc 10 to be reduced. Will be moved.

If the difference Df of the 64 tracks is not shown as a result of the determination in step 124, the difference Df obtained by multiplying the servo coefficient correction value ba in steps 126, 128, 130 or 132 is obtained. It is judged sequentially whether it is 16 tracks, 8 tracks, 4 tracks or more than 1 track (referred to as each step being more than 2nd, 3rd, 4th and 5th sections), and according to the determination result, the track error correction unit ( In operation 90), the optical pickup transfer mechanism is applied to the track error correction signal through the amplifying unit 100 for the movement of the track corresponding to the difference Df for the optimized movement to the target track corresponding to the difference Df. By applying to the sled motor constituting the optical pickup device 50, the movement to the target track on the disk 10 is accurately and quickly performed.

As described above, according to the servo coefficient correction method for moving a disc track according to the present invention, the movement direction to the target track is determined according to the track movement command with respect to the target track, and thus the movement direction to the determined track, that is, the inner track or the outer track. Determine the movement of the track, calculate the error value of the current track for the target track, determine the track shift correction coefficient based on the calculated error value, and perform servo for track movement. It can be done at a high speed.

Claims (2)

In a track servo control method of an optical disc for calculating track error from a current track position to a target track according to a track jump command, the track servo control method of the optical disc determines a moving direction to a target track according to a track jump command for the target track. When the track moves in the determined movement direction, the current track position is subtracted from the target track position to calculate the error value of the current track with respect to the target track, and the number of blocks / tracks existing in the inner and outer tracks based on the calculated error value. According to the result obtained by multiplying the number of moving tracks set to a certain number of tracks, the track servo coefficient correction value which is divided into stages from N or more until the first to fifth sections or more is determined step by step is determined. Track servo coefficient when moving tracks of an optical disc, characterized in that the movement takes place in a short time Positive way. The track servo coefficient corrections, which are divided into sections from the section N or more to the first to fifth section or more and are optimized step by step, are 128 tracks, 64 tracks, 16 tracks, 8 tracks, and 4 tracks, respectively. And the track servo coefficient correcting at the time of moving the track of the optical disc, characterized in that it corresponds to the difference Df for one track and is gradually decreased as the number of moving tracks approaches the track error for the number of target tracks.