KR20000025396A - Method for controlling servo - Google Patents

Abstract

PURPOSE: A method for controlling a servo is provided to conduct faster speed and exact track jumping operation by making a servo operation for compensating an eccentric amount be performed after detecting the eccentric amount of an optical disk before the track jump operation. CONSTITUTION: A method for controlling a servo comprises the steps of: detecting an eccentric amount of a present optical pickup at a track jump; calculating the number of shift tracks for shifting the optical pickup up to a target track; compensating the number of the calculated shift tracks on the basis of the eccentric amount of the detected optical pickup; and performing a track jumping operation corresponding to the number of the compensated shift tracks.

Description

Servo Control Method to Compensate Eccentricity of Optical Disk

The present invention relates to a servo control method for an optical disc, and more particularly, to detect an eccentric amount of an optical disc when an optical disc is inserted, calculate and store a compensation value corresponding to the eccentric amount, and thereafter, track jump operation. In this case, the servo operation control is performed by using the stored compensation value, thereby minimizing track jump error according to the amount of eccentricity of the optical disc, thereby compensating the eccentricity of the optical disc for more accurate and faster track jump operation. It is about.

A typical optical disc player filters an optical pickup (P / U) 2 for reading out a signal recorded on the optical disc 1 and a signal read out by the optical pickup 2, as shown in FIG. Filtering section 3 for shaping and outputting as RF (Radio Frequency) signal, Sync detecting section 7 for detecting a synchronization signal from the RF signal, and synchronizing the RF signal with a digital signal A digital signal processor (DSP) 4 for processing a reproduction signal, a MPEG decoder 5 for decoding the digital signal and outputting the original video or audio signal, and the optical pickup 2 Sled motor 11 for moving the shaft, Spindle motor 12 for rotating the optical disk 1, and driving the rotation of the sled motor 11 and the spindle motor 12 Driver 8, Servo 6 for controlling the optical pickup 2 and driver 8, Servo 6 and D And a memory 10 for storing the data (Data) necessary for the control operation of the microcomputer 9, and a micom 9 for controlling the operation of the digital signal processing unit 4. FIG.

The operation of a general optical disc player constructed as described above is as follows.

First, when the optical disc 1 is seated and inserted into a tray (not shown) provided in the optical disc player, it is clamped by a clamper (not shown), and then supplied from the driver 8. According to the driving voltage, the spindle motor 11 is rotated at a constant speed at about 2,500 rpm at constant speed, thereby rotating the optical disc 1 at a constant speed.

Thereafter, the optical pickup 2 emits a laser diode of the optical pickup 2 so as to read a signal recorded on the recording surface of the optical disc 1 to form an optical spot on the recording surface. Then, the reflected light of the formed light spot is converted into an electrical signal using a photo diode provided in the optical pickup 2. The converted and output electrical signal is converted into an RF signal by the filter shaping section 3, and is again processed by the digital signal processing section 4 into a digital signal. Is received by the synchronous detection unit 7 that receives the RF signal, which is an output signal of the N, and detects and outputs a synchronous signal included in the RF signal.

In addition, the synchronization signal output by the synchronization detection unit 7 is applied to the servo unit 6 that controls the tracking and focusing operation of the optical pickup 2, so that the servo operation and the digital operation of the servo unit 6 are performed. The signal processing operation of the signal processing section 4 is synchronized.

On the other hand, the driver 8 for driving the spindle motor 12 and the sled motor 11 is controlled by the servo unit 6, the sled motor 11, the optical pickup (2) It is controlled by the servo unit 6 when performing a track jump operation for greatly moving the optical disk track in the transverse direction, that is, a track search operation for largely traversing and moving the track of the optical disk 1. .

Hereinafter, the track search operation will be described. First, when the track search mode is set in response to a user's key input, the microcomputer 9 performs an operation of the optical disc reproduced by the optical pickup 2. The current track is detected, a track position difference with the search track selected by the key input is calculated, and a track search operation for moving the optical pickup 2 by the number of the corresponding tracks is performed.

However, the track jump operation for the track search is calculated by the number of movement tracks calculated under the assumption that the object lens (OL) provided in the optical pickup 2 is always located at the center of the actuator. Since the optical pickup 2 is moved, the objective lens can be shifted in the amount of deviation of the objective lens, that is, specifically, in an actuator holding, for example, the objective lens OL. Since the current position of the objective lens located within the deviation range corresponding to the deviation range of about 200 to 300 tracks is not taken into account, accurate track jump operation cannot be performed. Moreover, the amount of eccentricity of the optical disc track due to an error in the optical disc manufacturing process Alternatively, when the optical disk is inserted, the deviation of the objective lens is greatly generated according to the amount of eccentricity of the optical disk due to the clamping operation error, so that a track jumping error occurs frequently. There are problems that occur.

Therefore, the present invention was created to solve the above problems, and when the eccentric amount of the optical disc due to an error in the manufacturing process or the mounting of the optical disc, the eccentric amount of the optical disc due to the clamping operation error is detected before the track jump operation, A servo control method for calculating and storing a compensation value corresponding to an eccentric amount of an optical disc, and then compensating for an eccentric amount of an optical disc for accurate servo operation by controlling a track jump operation using the stored compensation value during track jumping. The purpose is to provide.

1 is a configuration diagram of a general optical disc player,

2 is an eccentricity detection state diagram of an optical disk according to the present invention;

3 is a state error detection state of the central error (CE) according to the present invention,

4 is a flowchart illustrating an operation of calculating a compensation value corresponding to an optical disc eccentricity according to an embodiment of the present invention.

5 is a flowchart illustrating a track jumping operation according to an embodiment of the present invention.

6 is a flowchart illustrating an operation of calculating a compensation value corresponding to an optical disc eccentricity according to another embodiment of the present invention;

7 is a flowchart illustrating a track jumping operation according to another embodiment of the present invention.

※ Explanation of code for main part of drawing

1: Optical disc 2: Optical pickup (P / U)

3: Filtering part (R / F) 4: Digital signal processing part (DSP)

5: MPEG decoder 6: Servo

7: Sync detection unit 8: Driver

9: Micom 10: Memory

11: Sled Motor 12: Spindle Motor

Servo control method for compensating the eccentricity of the optical disk according to the present invention for achieving the above object, the first step of driving the spindle motor to rotate the optical disk at a constant speed; Detecting an eccentricity of the rotating optical disk; And three steps of setting and storing a value for calculating a compensation value at the time of moving the track according to the detected eccentric amount, and further, compensating the eccentric amount of another optical disk according to the present invention. Is a first step of detecting a current optical pickup deviation amount during track jumping; Calculating a number of moving tracks for moving the optical pickup to a target track; Compensating the calculated number of moving tracks based on the detected deviation amount of the optical pickup; And performing a track jump operation in accordance with the compensated number of moving tracks. The servo control method for compensating an eccentricity of another optical disk according to the present invention includes the present invention. Detecting an optical pickup deviation amount; Calculating a driving voltage value of a sled motor for moving the optical pickup to a target track; Compensating the calculated driving voltage value based on the detected deviation amount of the optical pickup; And performing a track jump operation by driving a sled motor with the compensated driving voltage value.

In the servo control method for compensating the eccentricity of the optical disc 1 according to the present invention, the focusing is performed to control the position of the objective lens OL provided in the optical pickup 2 when the optical disc 1 is inserted. From a servo error and a center error (CE) of the photodiode (PD) detected by blocking the tracking servo operation and rotating the optical disc at a constant speed during the tracking servo operation. The amount of eccentricity of the optical disc is detected, and a compensation value corresponding to the detected amount of eccentricity is calculated and stored. Subsequently, by controlling the track jumping operation using the stored compensation value during the track jumping operation, the servo control compensates for the eccentricity of the optical disk due to an error in the manufacturing process or the optical disk due to a clamping operation error when the optical disk is inserted / seated. The action is to be made.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

2 is an eccentricity detection state diagram of an optical disk according to the present invention. As described above, an optical disk 21 inserted and seated in a tray (not shown) provided in an optical disk player has an error in manufacturing process or an error in clamping operation. Because of this, when the recording surface of the optical disc, i.e., the track on which the signal is recorded, is eccentric from the central axis, focusing is performed to control the position of the objective lens OL provided in the optical pickup 2. During the servo operation and the tracking servo operation, the tracking servo operation is interrupted, and the optical disc is rotated at a constant speed so that the deviation amount of the optical pickup 2 according to the eccentricity of the optical disc, that is, the photodiode PD The center error (CE: AC) value and the traverse signal detected according to the eccentric track of the optical disc are detected to detect the amount of deviation of the optical pickup 2.

Detailed description of the central error (CE) value will be described with reference to FIG. 3. First, FIG. 3 is a state error detection state diagram according to the present invention, and the objective lens included in the optical pickup 2 ( 31), an actuator 30 for holding the objective lens, and a reflective light spot (BS: Beam Spot) of the optical disc 1 passing through the objective lens 31, and receiving the center. A photodiode (PD) 32 is shown for detecting an error (CE) value.

The objective lens 31 held by the actuator 30 is designed to be able to flow within a predetermined range from the center position of the actuator, so that it is not track jumped by driving the sled motor 11. By the tracking servo operation, that is, the tracking servo operation of moving the objective lens in the horizontal direction, the objective lens 31 accurately tracks and reproduces the track of the optical disc 1.

The flow range of the objective lens 31 as described above corresponds to about 200 to 300 tracks, calculated in the track unit of the optical disc 1, and the position of the objective lens 1 is the actuator 30 when the track is jumped. If the center error (CE) has a positive or negative value other than zero, the track position to be searched and the current track position being played In addition, accurate track jump is achieved when the objective lens 31 calculates the amount of deviation from the center of the actuator 30 to perform track jump.

However, when the track jump operation is performed without considering the deviation amount of the objective lens 31, the tracking servo operation and the sled motor 11 driven during the track jumping operation are performed. Due to the inertial force that the optical pickup 2 is moved by, the accurate track jump is impossible. Furthermore, the track jump error is larger due to an eccentric amount of the optical disc or an eccentric amount of the optical disc due to a clamping operation error due to an error in the manufacturing process. Will be done.

Therefore, by detecting the track state of the optical disc, that is, the amount of eccentricity of the optical disc in advance, calculating and storing a compensation value corresponding to the detected eccentric amount, and then controlling the track jumping operation by using the stored compensation value during track jumping. It is possible to minimize track jump errors caused by the amount of eccentricity of the optical disc.

As described above, a servo control method for compensating an eccentric amount of an optical disc according to the present invention for minimizing track jump error according to the eccentric amount of an optical disc will be described in detail with reference to the accompanying drawings.

4 and 5 are flowcharts showing the operation of calculating the compensation value corresponding to the amount of eccentricity of the optical disk and the track jumping operation according to the embodiment of the present invention. First, the optical disk 1 is seated on a tray of the optical disk player. When inserted (S10), a clamping operation is performed by a clamper provided in the optical disc player.

When the optical disc is fixed by the clamping operation, the microcomputer 9 sets a test mode S11 for measuring the amount of eccentricity of the fixed optical disc, so that the spindle motor 11 corresponds to the normal playback speed. The optical disk is rotated at about 2500 rpm to rotate at a constant speed (S12).

Thereafter, the focusing servo operation of moving the objective lens OL 31 in the vertical direction in order to read out the signal recorded on the recording surface of the optical disc 1, that is, the track, is turned on (S13), The tracking servo operation for moving the objective lens 31 in the horizontal direction in the actuator 30 is turned off. In the above state, while the optical disk 1 is rotated N (for example, one rotation) (S16), the maximum amplitude A of the center error CE output from the photodiode PD 32 and the optical pickup 2 ) Detects the count number N of traverse signals traversing the track of the optical disc (S17), and detects the amount of eccentricity of the optical disc.

The maximum amplitude A of the center error CE detected and the count number N of the traverse signal correspond to the deviation amount of the optical pickup 2 according to the track state of the optical disc 1. The compensation value F (N) for compensating for the deviation amount is set in Equation 1 as follows and stored in the memory 10 (S18).

F (N) = (A '/ A) X (N / 2) -------------------------- Equation 1

A ': Amplitude of the center error detected during track jump

A: Maximum amplitude of the detected center error in measurement mode

N: Counted track crossings in measurement mode

Thereafter, when the user's key is input during the playback operation (S20), the microcomputer 9 sets the track search mode (S21), and the current track position at which the optical pickup 2 is playing. And calculating a target track number at which the optical pickup 2 should be moved by calculating a track position to search for in response to the key input (S23), while the compensation value F stored in the memory 10 is calculated. (N)), a compensation value F (N) corresponding to the amplitude of the detected current center error CE is calculated. The compensation value calculated as described above is for compensating the amount of the optical pickup 2 is currently shifted, and is calculated with the target track number, thereby calculating the number of moving tracks in which the shift amount of the optical pickup 2 is considered (S24). ) Thereafter, the microcomputer 9 rotates the spindle motor 12 at a speed suitable for the track search mode, for example, 6,000 rpm, at high speed (S25), and drives the sled motor 11 (S26) to pick up the optical pickup ( 2) is controlled to move by the calculated number of moving tracks.

When the operation is completed, the microcomputer 9 detects the current track position of the moved optical disc, and determines whether the position of the detected current track matches the position of the search track (S27). If the result of the determination does not match, a fine search operation (S27) is performed to finely move the objective lens 31 in the actuator 30 to change the playback track of the optical disc. The spindle motor 12 is controlled (S28) to rotate at about 2,500 rpm corresponding to the normal regeneration speed so that the regeneration operation (S29) is performed.

6 and 7 are flowcharts illustrating an operation of calculating a compensation value corresponding to an eccentric amount of an optical disc and a track jumping operation according to another embodiment of the present invention. First, the micom 9 includes: As described above with reference to FIG. 4, an eccentric amount of the optical disk is detected through a series of processes (S40 to S47), and the driving voltage of the sled motor 11 corresponding to the detected eccentric amount, that is, during track jump, is taken up. In order to compensate for the driving voltage of the driver 8 applied to the sled motor 11 to move (2), the driving voltage of the sled motor is calculated and stored (S48).

The driving voltage of the sled motor 11 corresponds to an experimental value obtained based on the track jump error value according to the eccentricity in the design of the optical disc player, and corresponds to the degree of eccentric track and the number of eccentric tracks of the optical disc. Correspondingly, the magnitude of the driving voltage of the sled motor 11 is set.

Thereafter, when the user's key is input during the playback operation (S50), the microcomputer 9 sets the track search mode (S51), and the current track position at which the optical pickup 2 is playing. And by calculating the track position to be searched, the optical pickup 2 calculates the target track number to be moved (S52). Thereafter, the drive voltage value of the sled motor corresponding to the detected current center error (CE) value is read out from the memory 10, while the spindle motor 12 has a speed suitable for the track search mode, For example, while driving at high speed (S53) at 6,000rpm, and driving the sled motor 11 to move the optical pickup 2 by the calculated target track number (S54), the memory 9 is read from the memory 9 By driving the sled motor with the drive voltage value of the sled motor, the optical pickup 2 is controlled to move exactly as the calculated number of moving tracks.

When the operation is completed, the microcomputer 9 detects the current track position of the moved optical disc, determines whether or not the position of the detected current track matches the position of the search track (S56), and agrees with the determination result. Otherwise, a fine search operation (S59) for finely moving the objective lens 31 in the actuator 30 to change the playback track of the optical disc is performed. If the result of the determination matches, the spindle motor 12 By controlling (S57) to rotate at about 2,500rpm corresponding to the normal playback speed so that the playback operation (S58) is made.

In this way, the eccentricity of the optical disc is detected, the compensation value corresponding to the detected eccentricity is calculated and stored, and during the track jump operation, the center error (CE) value is detected and the track jump operation is performed with the corresponding compensation value. By controlling this, accurate track jump operation is made.

In the servo control method for compensating an eccentricity of an optical disc according to the present invention, the eccentricity of an optical disc due to an error in a manufacturing process or an eccentric amount of an optical disc due to a clamping operation error is detected before a track jump operation to compensate for the eccentricity. By making the servo operation to be performed, it is a useful invention to achieve a faster, more accurate track jump operation.

Claims (5)

Driving the spindle motor to rotate the optical disc at a constant speed; Detecting an eccentricity of the rotating optical disk; And And setting and storing a value for calculating a compensation value during track movement according to the detected amount of eccentricity. The method of claim 1, The second step is a servo control method for compensating the eccentricity of an optical disc, characterized in that the eccentricity is detected based on the amount of change in the center error value of the objective lens detected in a state where the tracking servo operation is blocked. Detecting a current amount of optical pickup deviation in track jumping; Calculating a number of moving tracks for moving the optical pickup to a target track; Compensating the calculated number of moving tracks based on the detected deviation amount of the optical pickup; And And a four step of performing a track jump operation corresponding to the compensated number of moving tracks. Detecting a current amount of optical pickup deviation in track jumping; Calculating a driving voltage value of a sled motor for moving the optical pickup to a target track; Compensating the calculated driving voltage value based on the detected deviation amount of the optical pickup; And And a four step of performing a track jump operation by driving a sled motor with the compensated driving voltage value. The method of claim 4, wherein The fourth step is a servo control method for compensating for the eccentricity of the optical disk, characterized in that for adjusting the gain (Gain) value of the drive voltage applied to the sled motor.