JP2011134425A - Optical disk device and method of controlling seek of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a seek precisely, stably, and rapidly. <P>SOLUTION: An optical disk device includes: an eccentricity learning unit 90 for learning two rotary positions and the amount of eccentricity in a spindle motor 15 where the amount of eccentricity is maximized to an optical pickup 55 according to a relationship between the rotary position of the spindle motor 15 and the amount of eccentricity of an optical disk 10; a lens shift learning unit 80 for learning a relationship between a detection signal indicating the amount of lens shift from a lens center generated from reflection light of light beams and an actual amount of shift of a lens 20; and a control unit for correcting the moving distance of the optical pickup 55 from a current recording track to a target recording track using the actual amount of lens shift in the detection signal before the movement of a thread and the amount of eccentricity in the optical disk at a rotary position where the amount of eccentricity is maximized when allowing the light beams to perform a seek from the current recording track to the target recording track by a long seek, and performs track ON of the light beams at the rotary position where the amount of eccentricity is maximized. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus and a seek control method for an optical disc apparatus that can perform seek with high accuracy, stability, and speed.

  An optical disc has recording tracks arranged concentrically or spirally. The optical disc apparatus controls the tracking of the optical pickup in order to rotate the optical disc so that the light beam emitted from the optical pickup always follows the target recording track.

  When moving to the target recording track, the optical disk device moves the optical pickup itself using a sled that moves the optical disk in the radial direction and the objective lens of the optical pickup using the actuator. The target track is reached by using two types of seeks of short seek. The long seek is used when the distance between the current track and the target track is large. By moving the sled with the tracking control turned off, the long seek can be moved near the target position at high speed. However, since it is not possible to move in units of one track, the number of tracks is counted using a short seek and moved to the target track.

  Tracking control is control for causing a light beam to follow a target recording track, and is caused by a mechanical rotation center shift that occurs when an optical disk is fixed to a drive device, and a rotation center shift of the optical disk itself. Can be compensated for.

  However, when moving a light beam that requires a long seek (for example, 2 cm), the eccentric component adversely affects the operation of the seek, and the light beam can be accurately and stably and quickly moved to the target recording track. Sometimes it cannot be moved.

  Therefore, conventionally, various techniques as described in the following patent documents have been proposed in order to perform a seek operation accurately even when there is an eccentric component.

  In the technique described in the cited document 1, the eccentric component of the optical disc is learned, and when the seek is performed, the learned eccentric component is added to the jump signal to generate a drive signal. Driven (see paragraph 0039).

  In the technique described in the cited document 2, the eccentric component of the optical disc is learned, and the light beam is emitted when the voltage value of the drive signal is near the reference voltage (near the eccentric component becomes 0: see FIG. 4). The recording track is drawn to follow (hereinafter referred to as track ON) (see paragraphs 0032 and 0033).

  In the technique described in the cited document 3, when the seek is performed, the eccentric amount of the optical disc before the optical pickup is moved and the eccentric amount immediately after the optical pickup is predicted to correct the moving distance of the optical pickup. (See paragraph 0046 description).

  In the technique described in the cited document 4, when seeking is performed near the mirror area where the recording track does not exist on the optical disc, the calculation is actually performed to avoid the risk of the optical pickup moving into the mirror area. A certain amount of movement is subtracted from the amount of movement of the optical pickup, and the optical pickup is moved to an area outside the mirror area, and the track is turned on in an area other than the mirror area (see paragraph 0032).

JP 2000-20967 A JP 2003-272185 A JP 2004-39026 A JP 2000-339710 A

  However, these conventional techniques still have room for improvement in order to perform seek with high accuracy, stability and speed.

  In Patent Document 1, an eccentric component is added to a jump signal to generate a drive signal. However, as the eccentric component is larger, the voltage of the drive signal when the track is turned on after seek is shifted from the center. For this reason, the margin when the track is ON decreases, and there is room for improvement in terms of stable seek.

  In Patent Document 2, the influence of the eccentric component is reduced by turning on the track in the vicinity where the voltage value of the drive signal becomes the reference voltage, that is, in the vicinity where the eccentric component becomes zero. However, in the vicinity of the reference voltage, the relative position change between the lens of the optical pickup and the recording track is the fastest, so that it is difficult to turn on the track. Therefore, like Cited Document 1, there is room for improvement in terms of stable seeking.

  In Patent Document 3, the eccentric amount of the optical disk before the optical pickup is moved and the eccentric amount immediately after the optical pickup is predicted, and the moving distance of the optical pickup is corrected. However, the corrected moving distance does not reflect the shift amount of the lens of the optical pickup although the eccentricity amount is taken into consideration. In addition, since the timing of track ON is not taken into consideration, it is difficult to make the light beam follow the recording track stably. Therefore, like Cited Documents 1 and 2, there is room for improvement in terms of stable seeking.

  In Patent Document 4, in order to avoid seeking into the mirror area due to the influence of the eccentric component near the mirror area provided on the outer peripheral part and the inner peripheral part of the optical disc, the safety is considered from the movement amount of the optical pickup. The optical pickup is moved by reducing a certain distance. For this reason, the number of seeks until the target recording track is turned on increases, and the seek time increases. Therefore, there is room for improvement in terms of seeking with high accuracy and speed.

  An object of the present invention is to provide an optical disk apparatus and a seek control method for an optical disk apparatus that can perform high-accuracy, stable, and quick seeks by paying attention to such improvements of the conventional technology.

  In order to achieve the above object, an optical disc apparatus according to the present invention includes a spindle motor, a lens, a thread, an eccentricity learning unit, a lens shift learning unit, and a control unit.

  The spindle motor rotates the optical disk. The lens is supported by the actuator so as to irradiate the recording track of the optical disc with the light beam. The sled moves the optical pickup in a direction crossing the recording track. The eccentricity learning unit learns the two rotational positions and the eccentricity of the spindle motor at which the eccentricity is maximum with respect to the optical pickup from the relationship between the rotational position of the spindle motor and the eccentricity of the optical disk. The lens shift learning unit learns a relationship between a detection signal (CE signal) indicating the shift amount from the lens center generated from the reflected light of the light beam and the actual lens shift amount. When the control unit causes the optical beam to seek from the current recording track to the target recording track using the long seek, the learning distance of the optical pickup from the current recording track to the target recording track is learned and the lens. The movement distance corrected by correcting the optical pickup by correcting the actual lens shift amount in the CE signal before the sled movement calculated from the relationship with the shift amount and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum. The light beam is turned on at the rotational position where the amount of eccentricity is maximized. Then use short seek to reach the target track.

  In addition, a seek control method for an optical disc apparatus according to the present invention for achieving the above object includes a spindle motor for rotating an optical disc, an actuator for driving a lens to irradiate a recording track of the optical disc, and an optical pickup. A seek control method for an optical disc apparatus comprising a sled that moves in a direction intersecting with the optical pickup, wherein the amount of eccentricity relative to the optical pickup is determined from the relationship between the rotational position of the spindle motor and the amount of eccentricity of the optical disc. The two rotational positions and the eccentricity of the spindle motor that become the maximum are learned, and the detection signal (CE signal) indicating the shift amount from the lens center generated from the reflected light of the light beam and the actual lens shift Learn the relationship with the quantity and advance from the current recording track to the target recording track by thread When seeking the light beam, the movement distance of the optical pickup from the current recording track to the target recording track is actually calculated in the CE signal before moving the sled calculated from the relationship between the learned CE signal and the lens shift amount. The optical shift is corrected by the lens shift amount and the eccentric amount of the optical disc at the rotational position at which the eccentric amount is maximized, and the optical pickup is moved by the corrected moving distance, and the light at the rotational position at which the eccentric amount is maximized. Turn the beam on.

  Further, the seek control method of the optical disk apparatus according to the present invention for achieving the above object includes a spindle motor for rotating an optical disk, a lens supported by an actuator to irradiate a recording beam of the optical disk, and the lens. A seek control method for an optical disc apparatus having a thread for moving an optical pickup in a direction crossing a recording track, the amount of eccentricity relative to the optical pickup based on the relationship between the rotational position of a spindle motor and the amount of eccentricity of the optical disc Eccentric learning stage for learning the two rotational positions and the eccentricity of the spindle motor where the maximum value is detected, and a detection signal (CE signal) representing the lens shift amount from the lens center generated from the reflected light of the light beam The lens shift learning stage to learn the relationship between the actual lens shift amount and the long seek When seeking the light beam from the current recording track to the target recording track, the moving distance of the optical pickup from the current recording track to the target recording track is calculated from the relationship between the learned CE signal and the lens shift amount. A moving distance correction stage for correcting with the actual lens shift amount in the CE signal before the sled movement and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum, and the target recording track position is the recording of the optical disc. When it is at a position more than a certain distance from the boundary of the region where the method is different, the light beam is emitted at one of the rotational positions that reach the first after the sled movement among the two rotational positions where the eccentricity is maximum. And a follow-up stage for turning on the track.

  Further, the seek control method of the optical disk apparatus according to the present invention for achieving the above object includes a spindle motor for rotating an optical disk, a lens supported by an actuator to irradiate a recording beam of the optical disk, and the lens. A seek control method for an optical disc apparatus having a thread for moving an optical pickup in a direction crossing a recording track, the amount of eccentricity relative to the optical pickup based on the relationship between the rotational position of a spindle motor and the amount of eccentricity of the optical disc An eccentricity learning stage for learning two rotational positions and an eccentricity amount of the spindle motor where the maximum is obtained, a CE signal representing the lens shift amount from the lens center generated from the reflected light of the light beam, and the actual lens Lens shift learning stage to learn the relationship with shift amount, and current recording using long seek When the optical beam seeks from the rack to the target recording track, the moving distance of the optical pickup from the current recording track to the target recording track is calculated before the sled movement calculated from the relationship between the learned CE signal and the lens shift amount. The moving distance correction stage for correcting the actual lens shift amount in the CE signal and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum, and the region where the target recording track position is different in the recording method of the optical disc When the light beam is located at a position that is not separated from the boundary of the recording medium by a certain distance or more, the light beam is rotated at a rotational position where the thread position is further away from the boundary of the region where the recording method is different, among the two rotational positions where the eccentricity is maximum. A tracking step for turning on the track.

  According to the optical disk apparatus and the seek control method of the optical disk apparatus according to the present invention, the movement distance of the optical pickup to the target track is determined in consideration of the lens shift amount before the optical pickup movement and the maximum eccentricity amount of the optical disk. In addition, the light beam is caused to follow the target track at a rotational position where the amount of eccentricity is maximized. As a result, highly accurate, stable and quick seek is possible.

  In addition, when the target recording track is located at a position more than a certain distance from the boundary between different areas of the optical disc recording method, the first of the two rotational positions where the eccentricity is the maximum after the sled movement. The light beam is caused to follow the target recording track at any rotational position that reaches the target position. As a result, stable and quick seek is possible.

  Further, when the position of the target recording track is at a position that is not more than a certain distance from the boundary of the area where the recording method of the optical disk is different, the recording method is different among the two rotational positions where the eccentricity is maximum. The light beam is caused to follow the target track at a rotational position where the thread position is further away from the boundary of the region. As a result, stable and quick seek is possible.

It is a block diagram of the optical disk device concerning this embodiment. 3 is an operation flowchart of the optical disc apparatus according to the present embodiment. 3 is an operation flowchart of the optical disc apparatus according to the present embodiment. 3 is an operation flowchart of the optical disc apparatus according to the present embodiment. It is a figure where it uses for description of eccentricity. FIG. 10 is a diagram for explaining a relationship between a center error (CE) signal for a recording track of an optical disc and a shift amount from the original position of the lens. It is a figure which shows the tracking error (TE) signal actually output from an analog signal processing circuit. It is a figure which shows the center error (CE) signal actually output from an analog signal processing circuit. It is a figure which shows the tracking error (TE) signal and center error (CE) signal when performing a seek.

  Embodiments of an optical disc apparatus and a seek control method for an optical disc apparatus according to the present invention will be described below with reference to the accompanying drawings.

  The embodiments described below are exemplarily shown for easy understanding of the technical idea of the optical disk apparatus and the seek control method of the optical disk apparatus according to the present invention. Therefore, the technical scope of the optical disk apparatus and the seek control method of the optical disk apparatus according to the present invention should be determined based on the description of the claims.

  In the optical disk apparatus and the seek control method of the optical disk apparatus according to the present embodiment, the optical pickup moves to the target track in consideration of the lens shift amount before the optical pickup movement and the maximum eccentricity of the optical disk during long seek. By correcting the distance and turning on the light beam at the rotational position where the amount of eccentricity is maximum, high-precision long seek is possible.

  Also, when seeking to a recording track in the vicinity of the mirror area where the recording track does not exist (for example, less than 500 μm from the mirror area), the thread position is closer to the center of the disk among the two rotational positions where the eccentricity is maximum. The rotation position is selected and the light beam is turned on. As a result, the risk of entering the mirror area can be greatly reduced even when the focus is off or the track is unsuccessful when the track is on. Therefore, even if the target track is in the vicinity of the mirror area, stable seek is possible.

  Furthermore, when seeking a recording track at a position away from the mirror area (for example, 500 μm or more), one of the two rotational positions where the eccentricity is maximized is one of the rotational positions that reaches the first after moving the sled. The light beam is turned on. Therefore, a faster seek is possible.

  In this embodiment, the boundary between the user area and the mirror area is described as an example of the boundary between areas having different recording methods. However, the present invention is not limited to this, and the present invention is not limited to this. The invention can be applied.

  FIG. 1 is a block diagram of an optical disc apparatus according to this embodiment.

  The optical disc apparatus 100 includes a spindle motor 15, a lens 20, a lens actuator 25, a laser diode 30, a half mirror 35, a light detection circuit 40, an analog signal processing circuit 45, a lens actuator driver 50, an optical pickup 55, a thread 60, and a thread driver 65. , A spindle motor driver 70, a track count unit 75, a lens shift learning unit 80, a rotational position detection unit 85, an eccentricity learning unit 90, and a control unit 95. The track count unit 75, the lens shift learning unit 80, the rotational position detection unit 85, the eccentricity learning unit 90, and the control unit 95 are provided in the system microcomputer.

  The spindle motor 15 rotates the optical disk 10 with the rotation hole of the optical disk 10 held on the rotation shaft. The spindle motor 15 outputs FG pulse signals of a fixed number (for example, 18 pulses or 36 pulses) for one rotation. The FG pulse signal is used to grasp how much angle the spindle motor 15 has rotated from the reference rotation position. That is, the rotational position of the spindle motor 15 can be determined by counting the number of pulses of the FG pulse signal.

  The lens 20 is supported by an actuator so as to irradiate the recording track of the optical disc 10 with a light beam. The lens 20 focuses the light beam on the recording track and causes the light beam to follow the recording track. In this embodiment, a DVD is exemplified as the optical disc 10.

  The lens actuator 25 drives the lens 20 so that the light beam that has passed through the lens 20 follows the recording track.

  The laser diode 30 outputs a light beam applied to the recording track of the optical disc 10 toward the lens 20.

  The half mirror 35 transmits a part of the light beam output from the laser diode 30 toward the lens 20. The light beam transmitted through the half mirror 35 is focused by the lens 20 and irradiated onto the recording track of the optical disc 10.

  The light detection circuit 40 inputs the reflected light of the light beam irradiated to the recording track of the optical disc 10 through the half mirror 35, photoelectrically converts it, and outputs a detection signal. The detection signal is an analog electrical signal. In addition to the function of transmitting the light beam as described above, the half mirror 35 also has a function of reflecting the reflected light of the light beam applied to the recording track toward the light detection circuit 40.

  The analog signal processing circuit 45 processes a detection signal that is an analog electric signal output from the photodetection circuit 40, and outputs a tracking error (TE) signal and a center error (CE) signal that are digital electric signals. . The tracking error signal can detect that the light beam has crossed the recording track. The center error signal can detect the shake of the lens 20 when the light beam follows the recording track. Therefore, in this embodiment, the tracking error signal is used for measuring the eccentricity of the optical disc, and the center error signal is used for measuring the shift amount of the lens 20.

  The lens actuator driver 50 outputs a drive signal to the lens actuator 25, and moves the lens 20 to irradiate the light beam along the recording track. Therefore, when the optical disk 10 is rotating eccentrically, the recording track rotates with an elliptical locus, so the lens actuator driver 50 outputs a driving signal for reciprocating the lens 20 to the lens actuator 25. It will be. Also, during a short seek, the lens is moved in a specified direction using the lens actuator 25 with the tracking control turned off, the number of sine wave TE signals is measured, and the target track is approached.

  The optical pickup 55 includes a lens 20, a lens actuator 25, a laser diode 30, a half mirror 35, and a light detection circuit 40.

  The thread 60 moves the optical pickup 55 in the radial direction of the optical disk 10 by rotating a lead screw having a spiral groove forward and backward by a thread motor. The sled 60 operates when the optical pickup 55 is moved during a long seek, or when the lens is moved by the amount of deviation from the center due to track following and is controlled so that the lens is always centered.

  The thread driver 65 outputs a drive signal to the thread 60 based on the thread control signal from the control unit 95. The sled 60 rotates the sled motor based on the drive signal and moves the optical pickup 55.

  The spindle motor driver 70 outputs a signal for controlling the rotation of the spindle motor 15 to the spindle motor 15. When the recording method is the CLV method, the spindle motor driver 70 reduces the rotation speed of the optical disc 10 as the irradiation position of the light beam moves from the inner periphery to the outer periphery of the optical disc 10. When the recording system is the CAV system, the optical disk 10 is rotated at a constant rotational speed regardless of where the irradiation position of the light beam is on the optical disk 10.

  The lens shift learning unit 80 moves the optical pickup 55 with the thread 60 and learns the relationship between the detection signal generated from the reflected light of the light beam and the shift amount of the lens 20. Detailed processing of the lens shift learning unit 80 will be described with reference to an operation flowchart of FIG.

  The rotational position detector 85 counts the number of pulses of the FG pulse signal output from the spindle motor 15 and detects the rotational position of the spindle motor 15 from the reference position.

  The eccentricity learning unit 90 has the maximum eccentricity with respect to the optical pickup 55 based on the relationship between the rotational position of the spindle motor 15 detected by the rotational position detection unit 85 and the eccentricity of the optical disk 10. Learn the rotational position of the location. When the optical disk 10 rotates with a certain eccentric component, when viewed from the optical pickup 55, the optical disk 10 is at a rotational position where the eccentricity is maximized every time the optical disk 10 is rotated 1/2. The eccentricity learning unit 90 has two rotational positions (calculated from the number of pulses of the FG pulse signal) at which the eccentricity becomes maximum each time the optical disk 10 makes one rotation, and the eccentricity amounts of the two rotational positions ( (Calculated from tracking error signal).

  When the control unit 95 seeks the light beam from the current recording track to the target recording track by the thread 60, the lens shift learning unit 80 determines the moving distance of the optical pickup 50 from the current recording track to the target recording track. The eccentricity of the optical disc 10 at the rotational position where the lens shift amount in the current detection signal calculated from the relationship between the learned detection signal and the lens shift amount and the eccentricity learned by the eccentricity learning unit 90 are maximized. Then, the optical pickup 55 is moved by the corrected moving distance, and control is performed to cause the light beam to follow the target track at the rotational position where the eccentricity is maximized.

  In addition, the control unit 95 has two locations where the amount of eccentricity becomes maximum when the position of the target recording track is at a position more than a certain distance from the mirror area of the optical disc 10 (for example, 500 μm or more from the mirror area). Of the rotational positions, control is performed to cause the light beam to follow the target track at any rotational position that first reaches after the sled movement.

  Further, when the target recording track is at a position that is not separated from the mirror area of the optical disk 10 by a certain distance or more, the controller 95 determines the thread position among the two rotational positions where the eccentricity is maximum. The rotational position closer to the inner circumference of the disc is selected to calculate the thread movement distance.

  In this embodiment, the case where the lens shift learning unit 80 is provided to learn the relationship between the detection signal and the shift amount of the lens 20 is illustrated, but the relationship between the detection signal and the shift amount of the lens 20 is known in advance. If there is a lens shift, the lens shift learning unit 80 may be replaced with a lens shift storage unit that stores the relationship between the detection signal and the shift amount of the lens 20.

  Next, the operation of the optical disk apparatus according to the present embodiment will be described with reference to the operation flowcharts of FIGS. 2 to 4 and the drawings of FIGS. 2 to 4 corresponds to the processing procedure of the seek control method for the optical disc apparatus according to the present embodiment.

  FIG. 2 is an operation flowchart of the optical disc apparatus according to the present embodiment. This operation flowchart shows the relationship between the rotational position at which the eccentric amount of the optical disc 10 is maximized, the eccentric amount, the detection signal, and the shift amount of the lens 20. The process for learning is performed.

  The measurement of the amount of eccentricity when the optical disc 10 is rotated eccentrically and the learning of the rotational position at which the amount of eccentricity becomes maximum and the amount of eccentricity at the rotational position are shown in FIG. The process performed by the unit 90, and learning of the relationship between the detection signal and the shift amount of the lens 20 is performed by the lens shift learning unit 80 shown in FIG.

  Before describing the operation flowcharts of FIGS. 2 to 4, the eccentricity of the optical disk 10 and the center error (shift amount) of the lens 20 will be described.

  FIG. 5 is a diagram for explaining eccentricity, and FIG. 7 is a diagram showing a tracking error (TE) signal actually output from the analog signal processing circuit 45.

  As shown in the figure, eccentricity refers to a state in which the rotation center Ca of the optical disc 10 and the rotation center Cb of the spindle motor 15 are shifted. When there is an eccentricity, the positional relationship between the locus of the light beam emitted from the optical pickup 55 and the recording track of the optical disc 10 changes depending on the rotational position of the optical disc 10. Therefore, a phenomenon occurs in which the recording track crosses the eccentric amount by the light beam.

  The cause of the eccentricity is a positional deviation that occurs when the optical disk 10 is held on the rotating shaft of the spindle motor 15 and a positional deviation of the rotation hole that occurs when the optical disk 10 is manufactured. As shown in FIG. 7, when the eccentricity occurs, the recording track traverses the optical beam by the amount of eccentricity, as shown in FIG. 7, the HI of the tracking error (TE) signal output from the analog signal processing circuit 45. , And can be captured by the change state of LOW. In the tracking error (TE) signal change state of HI and LOW shown in FIG. 7, the positions where the change periods of HI and LOW are the smallest are the positions A and B where the eccentricity shown in FIG. There are two places. These positions are referred to herein as poles. At these two pole positions, it becomes easy to draw the light beam into the recording track and follow it. In other words, it becomes easy to turn the light beam on the recording track. In the present embodiment, when the seek is performed to move the optical pickup 55 from the current recording track to the target track by 2 centimeters, when one of these poles comes, the light beam is Pull in the target track and follow it.

  When a long seek is performed, the eccentric state differs before and after the optical pickup 55 is sled-moved, so that the position of the optical pickup 55 causes an error with respect to the target recording track position. In the present embodiment, in order to eliminate this error, learning of the rotational position and the eccentric amount where the eccentric amount becomes maximum is performed.

  FIG. 6 is a diagram for explaining the relationship between the center error detection signal for the recording track of the optical disk and the shift amount from the original position of the lens, and FIG. 8 shows the analog when the track is turned on to a disk having an eccentricity of 50 μm. FIG. 9 is a diagram showing a center error (CE) signal actually output from the signal processing circuit, and FIG. 9 is a diagram showing a tracking error (TE) signal and a center error (CE) signal when seeking is performed.

  When the lens 20 is caused to follow the recording track of the optical disk 10 rotating in an eccentric state, a center error signal as shown in FIG. 8 is output as a detection signal. The center error signal is a signal output as a voltage value proportional to the amount of shift of the lens 20 in the radial direction. The current voltage value of the center error signal represents the shift amount from the original position of the lens 20. Simply put, it represents the current position of the lens 20.

  In a state where the light beam follows the recording track, the lens actuator 25 moves the lens 20 in accordance with the deflection of the recording track due to eccentricity. In a stable state after the track is turned on, the center error signal draws a sine waveform in accordance with the rotation of the optical disk 10, as shown in FIG. The center (DC component) of the center error signal in the Sin wave shape is the movement center position of the lens 20 that is reciprocating.

  However, when a long seek is performed, the center of the center error signal varies greatly as shown in FIG. 9 depending on the difference in the seek distance and the state when the track is turned on, and an offset may occur at the center. The shift amount of the lens 20 in this case is the sum of the eccentricity amount and the offset amount of the optical disc 10. When a long seek is performed in a state where the lens 20 is shifted, there is a problem that the offset amount before the seek is generated as a seek error as it is. This seek error cannot be solved only by correcting the eccentricity. This is because the offset of the center of the center error signal remains as an error without being corrected.

  In order to solve this problem, in the present embodiment, as shown in FIG. 6, when the relationship between the center error detection signal for the recording track of the optical disc 10 and the shift amount of the lens 20 is learned in advance and a long seek is performed. The shift amount of the lens 20 is calculated from the center error signal, and the moving distance of the optical pickup 55 is corrected. Note that when JumpFlag in FIG. 9 is HI, a short seek or a long seek is being performed.

  The above is the explanation of the eccentricity of the optical disc 10 and the center error of the lens 20.

  Next, processing of the operation flowchart of FIG. 2 will be described. This operation flowchart is executed at the initial startup immediately after the optical disk 10 is loaded.

  First, the eccentricity learning unit 90 performs eccentricity measurement. In the eccentricity measurement, the rotational position detector 85 detects the rotational position of the spindle motor 15 from the FG pulse signal output from the spindle motor 15, and the eccentricity learning unit 90 outputs the FG pulse signal each time the FG pulse signal is output. This is done by determining the amount of eccentricity. The FG pulse signal is output in a fixed number (for example, 18 pulses or 36 pulses) for one rotation of the spindle motor 15. Therefore, the eccentric amount of the optical disk 10 can be obtained according to the rotational position (every 20 ° or 10 °) of the spindle motor 15 (step S10). The amount of eccentricity for each FG pulse can be obtained by measuring the number of TE signals in the track OFF state.

  Next, the eccentricity learning unit 90 learns the rotational position where the eccentricity amount is maximum and the eccentricity amount from the result of the eccentricity measurement performed in step S10. Since the moving speed of the lens is the slowest at the rotational position where the amount of eccentricity is maximum, the number of TE signals between FG pulses is the smallest, and the FG pulse number is the pole position. As shown in FIG. 5, the positions of the poles with the maximum eccentricity are two points, point A and point B, and the total number of TE signals between the poles is the eccentricity. The eccentricity learning unit 90 learns the amount of eccentricity when the light beam output from the optical pickup 55 reaches two pole positions (step S20).

  In the seek control method for the optical disc apparatus according to the present embodiment, the processes in steps S10 and S20 correspond to the eccentricity learning stage.

  Then, the lens shift learning unit 80 learns the relationship between the detection signal and the shift amount (step S30). The detailed procedure of this step will be described based on the operation flowchart of FIG.

  FIG. 3 is a subroutine flowchart showing a detailed procedure of step S30 shown in FIG. This flowchart is for determining the relationship between the center error signal indicating the shift amount of the lens 20 and the actual lens shift amount, and is executed by the lens shift learning unit 80.

  First, the lens 20 is driven toward and away from the surface of the optical disc 10, and the light beam is focused on the recording layer to bring the focus ON (step S31). Next, the center error signal as shown in FIG. 8 is measured, and the initial value of the center error of the lens 20 is measured for one rotation of the optical disc 10. The initial value of the center error is an average value of the measured center errors (step S32). This initial value is a value indicating the center position of the lens.

  Then, the light beam is drawn into the recording track to follow it, and the track is turned on (step S33). The center error signal is measured again, and the center error of the lens 20 is measured for one rotation of the optical disk 10. The center error at this time is also the average value of the measured center errors (step S34).

  Next, the optical pickup 55 is moved by a certain distance, for example, 10 μm while keeping the track ON (step S35), the process returns to step S34 (step S36), the center error signal is measured again, and the center error is detected on the optical disk 10. Measure for one revolution. The center error at this time is also the average value of the measured center errors (steps S34 to S36).

  The processes of step S34 and step S35 are repeated a predetermined number of times (for example, 10 times) (step S36), and the average of center errors when the optical pickup 55 is moved by a certain distance is plotted. The sensitivity of the lens shift amount (the slope of the straight line indicating the value of the center error signal with respect to the lens shift amount) as shown in FIG. Alternatively, instead of obtaining the linear sensitivity as shown in FIG. 5, an average of center errors obtained when the optical pickup 55 is moved by a certain distance may be provided as a center error-Δ distance table (steps). S37).

  In the seek control method for the optical disc apparatus according to the present embodiment, the process of the flowchart in FIG. 3 corresponds to the lens shift learning stage.

  In this embodiment, as described above, the process of learning the relationship between the detection signal and the shift amount is performed. However, when the relationship between the detection signal and the shift amount is known in advance, this relationship is stored. As long as the optical disk apparatus includes the storage device, the process of step S30 in FIG. 2 and the process of the flowchart in FIG. 3 can be omitted.

  Next, based on the operation flowchart shown in FIG. 4, a process when the optical disc apparatus according to the present embodiment performs a long seek will be described in detail.

  First, the movement distance of the optical pickup 55 is calculated in order to seek the light beam output from the optical pickup 55 from the current recording track to the target recording track. This moving distance is calculated by how many recording tracks are skipped from the current recording track to the target recording track, and the calculated number of recording tracks is multiplied by the distance between the recording tracks that is known in advance. Calculation is performed by combining them (step S40). Next, referring to the sensitivity of the lens shift amount as shown in FIG. 6 learned by the lens shift learning unit 80, the current shift amount of the lens 20 is calculated from the center error signal corresponding to the detection signal (step S41). . The calculated shift amount of the lens 20 is added to the movement distance of the optical pickup 55 to correct the movement distance of the optical pickup 55 (step S42).

  Next, it is determined whether or not the position of the target recording track is near a mirror area where no recording track exists. Whether or not the position of the target recording track is near the mirror area is determined by whether or not the target track is within a distance of, for example, less than 500 μm from the mirror area (step S43). If the target track is near the mirror area (step S43: Yes), the learned eccentricity is maximized because the light beam is drawn into the target track at a position away from the mirror area to turn on the track. Among the FG pulse signal numbers, the FG pulse signal number that is less likely to be drawn into the mirror region, that is, the safe rotational position is selected. For example, in the case shown in FIG. By making such a selection, it is possible to reduce the possibility that the light beam enters the mirror area when there is any abnormality such as a focus drop or a track ON failure when the track is ON (step S44).

  If the target track is not close to the mirror area (step S43: No), the number of the FG pulse signal with the maximum learned eccentricity is required to draw the light beam into the target track and turn it on as soon as possible. The number of the FG pulse signal that can be reached first after moving the sled, that is, the rotational position, is selected from the rotational speed of the disk and the long seek time. For example, in the case of FIG. 5, when the optical pickup 55 can reach the pole of point A quickly, point A capable of reducing the time is selected (step S45).

  When the pole to be turned on is determined, the movement amount of the optical pickup 55 is further corrected by the eccentric amount corresponding to the number of the FG pulse signal of the selected pole. The correction of the shift amount of the lens 20 and the eccentricity amount of the optical disc 10 is completed by the corrections in steps S42 and S46, and the light beam can be accurately turned on the target recording track (step S46). .

  Then, the optical pickup 55 is moved by the corrected distance (step S47), and after waiting for the number of the FG pulse signal corresponding to the selected pole having the maximum eccentricity (step S48), the light beam is changed. The target recording track is turned on (step S49).

  In the seek control method for the optical disk apparatus according to the present embodiment, among the processes in the flowchart of FIG. 4, the processes in steps S42 and S46 correspond to the movement distance correction stage, and the processes in steps S47 to S49 are performed. Corresponds to the following stage.

  As described above, according to the optical disc apparatus and the seek control method of the optical disc apparatus of the present embodiment, the light up to the target track is considered in consideration of the lens shift amount before the optical pickup movement and the maximum eccentricity amount of the optical disc. This occurs when a long distance seek is performed on an optical disc with a large eccentricity by correcting the moving distance of the pickup and causing the optical beam to follow the target track at the rotational position where the eccentricity is maximized. It is possible to eliminate the seek error. Therefore, highly accurate seek can be performed.

  Even when seeking near the mirror area provided inside or outside of the optical disk, the track is turned on at the pole far from the mirror area, so that highly accurate and safe seek is possible. Therefore, highly accurate and stable seek can be performed.

  Furthermore, since the light beam is turned on to the target track at any one of the two rotational positions where the eccentricity reaches the maximum, the time required for seeking can be shortened. it can. Therefore, more rapid seek can be performed.

  As described above, in the embodiment, the optical disc apparatus and the optical disc apparatus seek control method according to the present invention have been described. However, it goes without saying that the present invention can be appropriately added, modified, and omitted by those skilled in the art within the scope of the technical idea.

  In this embodiment, the DVD is exemplified as the optical disk. However, as other optical disks, DVD-R, DVD-RW, DVD + R, DVD + RW, DVD-ROM, BD-ROM, BD-R, BD-RE are used. Of course, the present invention can also be applied to magneto-optical disks such as MO.

10 optical disc,
15 spindle motor,
20 lenses,
25 Lens actuator,
30 Laser diode,
35 half mirror,
40 photodetection circuit,
45 Analog signal processing circuit,
50 lens actuator driver,
55 Optical pickup,
60 threads,
65 thread driver,
70 spindle motor driver,
75 track count section,
80 Lens shift learning unit,
85 rotational position detector,
90 Eccentric learning part,
95 control unit,
100 Optical disk device.

Claims (7)

A spindle motor that rotates the optical disc;
A lens supported by an actuator to irradiate a light beam onto a recording track of the optical disc;
A thread for moving an optical pickup supporting the lens in a direction crossing the recording track;
Eccentricity for learning the two rotational positions and the eccentricity of the spindle motor where the eccentricity is maximized with respect to the optical pickup from the relationship between the rotational position of the spindle motor and the eccentricity of the optical disk. The learning department,
A lens shift learning unit for learning a relationship between a detection signal representing a lens shift amount from a lens center generated from the reflected light of the light beam and an actual lens shift amount;
When the optical beam is sought from the current recording track to the target recording track using the long seek, the moving distance of the optical pickup from the current recording track to the target recording track is calculated using the learned detection signal and the lens shift amount. It is corrected by the actual lens shift amount in the detection signal before the sled movement calculated from the relationship and the eccentricity amount of the optical disk at the rotational position where the eccentricity is maximized, and the optical pickup is moved by the corrected moving distance to be eccentric. A controller that turns on the light beam at a rotational position where the amount is maximum;
An optical disc apparatus comprising:   The optical disc apparatus according to claim 1, further comprising a lens shift storage unit that stores a relationship between a detection signal generated from reflected light of the light beam and the lens shift amount, instead of the learning unit. The controller is
When the position of the target recording track is at a position more than a certain distance from the boundary between different areas of the recording method of the optical disk, after moving the sled among the two rotational positions where the eccentricity is maximum. 3. The optical disc apparatus according to claim 1, wherein the optical beam is turned on at any rotation position that reaches first. The controller is
When the position of the target recording track is at a position that is not more than a certain distance from the boundary between the different areas of the recording method of the optical disc, the recording method is selected from the two rotational positions where the eccentricity is maximum. The optical disk apparatus according to claim 1, wherein the optical beam is turned on at a rotational position where a thread position is further away from a boundary between different areas. An optical disk comprising a spindle motor for rotating an optical disk, a lens supported by an actuator to irradiate a recording beam of the optical disk, and a thread for moving an optical pickup supporting the lens in a direction intersecting the recording track A device seek control method comprising:
Eccentricity for learning the two rotational positions and the eccentricity of the spindle motor where the eccentricity is maximized with respect to the optical pickup from the relationship between the rotational position of the spindle motor and the eccentricity of the optical disk. Learning phase,
A lens shift learning step of learning a relationship between a detection signal representing a lens shift amount from a lens center generated from the reflected light of the light beam and an actual lens shift amount;
When the optical beam is sought from the current recording track to the target recording track using the long seek, the moving distance of the optical pickup from the current recording track to the target recording track is calculated using the learned detection signal and the lens shift amount. A moving distance correction stage for correcting with the actual lens shift amount in the detection signal before the sled movement calculated from the relationship and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum;
A tracking step of moving the optical pickup to a corrected moving distance and turning on the light beam at a rotational position where the eccentricity is maximized,
A seek control method for an optical disc apparatus, comprising: An optical disc comprising a spindle motor for rotating an optical disc, a lens supported by an actuator to irradiate a recording beam of the optical disc, and a thread for moving an optical pickup supporting the lens in a direction crossing the recording track A device seek control method comprising:
Eccentricity for learning the two rotational positions and the eccentricity of the spindle motor where the eccentricity is maximized with respect to the optical pickup from the relationship between the rotational position of the spindle motor and the eccentricity of the optical disk. Learning phase,
A lens shift learning step of learning a relationship between a detection signal representing a lens shift amount from a lens center generated from the reflected light of the light beam and an actual lens shift amount;
When the optical beam is sought from the current recording track to the target recording track using the long seek, the moving distance of the optical pickup from the current recording track to the target recording track is calculated using the learned detection signal and the lens shift amount. A moving distance correction stage for correcting with the actual lens shift amount in the detection signal before the sled movement calculated from the relationship and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum;
When the position of the target recording track is at a position more than a certain distance from the boundary between different areas of the recording method of the optical disk, after moving the sled among the two rotational positions where the eccentricity is maximum. A follow-up phase that tracks on the light beam at any rotational position that reaches first;
A seek control method for an optical disc apparatus, comprising: An optical disc comprising a spindle motor for rotating an optical disc, a lens supported by an actuator to irradiate a recording beam of the optical disc, and a thread for moving an optical pickup supporting the lens in a direction crossing the recording track A device seek control method comprising:
Eccentricity for learning the two rotational positions and the eccentricity of the spindle motor where the eccentricity is maximized with respect to the optical pickup from the relationship between the rotational position of the spindle motor and the eccentricity of the optical disk. Learning phase,
A lens shift learning stage for learning a relationship between a detection signal representing a lens shift amount from a lens center generated from the reflected light of the light beam and an actual lens shift amount;
When the optical beam is sought from the current recording track to the target recording track using the long seek, the moving distance of the optical pickup from the current recording track to the target recording track is calculated using the learned detection signal and the lens shift amount. A moving distance correction stage for correcting with the actual lens shift amount in the detection signal before the sled movement calculated from the relationship and the eccentric amount of the optical disc at the rotational position where the eccentric amount is maximum;
When the position of the target recording track is at a position that is not more than a certain distance from the boundary of the different areas of the optical disc recording method, the recording method differs among the two rotational positions where the eccentricity is maximum. A follow-up step for turning on the light beam at a rotational position where the thread position is further away from the boundary of the region;
A seek control method for an optical disc apparatus, comprising: