JP2011248941A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device capable of properly correcting a radial skew of a surface wobbling disk while suppressing cost increase.SOLUTION: In a control part of the optical disk device, the drive control amount is measured which drives an objective lens in a focusing direction by performing focus servo control in a state where optical pickup is located at a prescribed position, and on the basis of the measured drive control amount, the surface wobbling correction tilt control is performed by acquiring a tilt control condition in which inclination of the tilt direction of the objective lens is changed in accordance with a surface shake period of an optical disk.

Description

  The present invention relates to an optical disc apparatus used for reproducing information recorded on an optical disc or recording information on an optical disc, and more particularly to a technique for correcting a radial skew of a surface runout disc.

  2. Description of the Related Art Conventionally, optical disk devices that rotate an optical disk to reproduce information on the optical disk or record information on the optical disk have become widespread. This optical disc apparatus includes an optical pickup that irradiates light to the optical disc and detects return light (reflected light) reflected by the optical disc, and uses this optical pickup to read and write information. The optical disc apparatus is configured to generate a reproduction signal and a signal for performing servo control (for example, a focus drive signal, a tracking drive signal, etc.) by processing a signal output from the optical pickup.

  The optical pickup is provided with an objective lens so that the light emitted from the light source can be condensed on the information recording surface of the optical disk. The objective lens can be moved at least in the focus direction and the tracking direction by the objective lens actuator so that focus servo control and tracking servo control can be performed.

  Here, the focus direction is a direction substantially orthogonal to the information recording surface of the optical disc, and the tracking direction is a direction substantially parallel to the radial direction of the optical disc. The focus servo control refers to control performed so that the focal position of the objective lens does not deviate from the information recording surface, and the tracking servo control refers to the light spot collected by the objective lens following the track of the optical disk. It refers to the control to be performed.

  By the way, among optical discs in which information is reproduced and recorded by such an optical disc apparatus, there is a so-called surface wobble disc in which the position of an information recording surface (disc surface) moves up and down when it is rotated (for example, (See Patent Documents 1 and 2). As shown in FIG. 12, in the optical disc apparatus, even if it is a surface shake disc, the distance between the objective lens 101 and the optical disc D is kept substantially constant by focus servo control using the objective lens actuator, and the focus of the objective lens 101 is increased. The optical disk can be reproduced and recorded without removing the position from the information recording surface of the optical disk D.

  In FIG. 12, the symbol O is the rotation center of the optical disc D. FIG. 12 shows a state where the optical disc D is moved up and down due to surface deflection.

  However, as shown in FIG. 12, when a surface runout disc is reproduced, radial skew (inclination with respect to the reference direction when the radial direction of the optical disc D without surface runout is used as the reference direction) occurs. The optical axis AX of the objective lens 101 and the information recording surface (front surface) of the optical disc D are not in a relationship orthogonal to each other, and there is a problem that jitter deteriorates. In this regard, some conventional optical disk apparatuses guarantee the reproduction and recording performance by the skew margin of the optical pickup (the margin with respect to the specified jitter) without providing the function of correcting the radial skew.

  Conventionally, as shown in Patent Document 1, for example, the structure of an objective lens driving device (objective lens actuator) is configured so that a movable part having an objective lens cancels a radial skew generated in synchronization with surface shake. Some have corrected the radial skew of the optical disc by making the posture changeable. According to this, it is possible to suppress the deterioration of jitter during reproduction of the optical disk or the like.

  Note that the structure in which the movable portion changes its posture in synchronization with the surface vibration period (synchronized with the movement in the focus direction) has a plurality of elastic members that connect the movable portion and the fixed portion in order to support the movable portion ( With regard to a leaf spring or a wire, it is mentioned that characteristics are different between a member located on the inner peripheral side of the disk and a member located on the outer peripheral side. As another configuration, A) a configuration in which the length of the elastic member is changed between the movable portion and the fixed portion on the inner and outer peripheral sides of the disk, and B) the support center of the movable portion by the elastic member. On the other hand, there is a configuration in which the drive center of the movable part is provided at a position biased toward the outer peripheral side of the disk.

JP 2003-157560 A JP 2009-20926 A

  However, the above-described configuration that guarantees the reproduction performance by using the skew margin of the optical pickup is also caused by factors other than the radial skew of the optical disk (for example, aberration generated in the optical system of the optical pickup, contamination of the optical disk, etc.). Since this may occur, a situation in which performance guarantee such as reproduction is not sufficient is likely to occur.

  Further, as shown in Patent Document 1, the objective lens actuator is configured so that the posture of the movable portion is changed in accordance with the movement in the focus direction, because parts management at the time of manufacture (part type management, part size management) Etc.) in terms of cost. In recent years, an optical disc apparatus is generally provided so as to be compatible with a plurality of types of optical discs such as a BD (Blu-ray disc), a DVD (Digital Versatile Disc), and a CD (Compact Disc). . In such an optical disc apparatus, the working distance (distance between the tip of the objective lens and the optical disc) generally differs depending on the type of the optical disc. For this reason, in the objective lens actuator as shown in Patent Document 1, it may be difficult to appropriately correct the radial skew for all types of optical disks.

  Accordingly, an object of the present invention is to provide an optical disc apparatus capable of appropriately correcting a radial skew of a surface runout disc while suppressing an increase in cost. Another object of the present invention is to provide an optical disc apparatus that can appropriately correct the radial skew of a surface run-out disc even when it can cope with a plurality of types of optical discs.

  In order to achieve the above object, an optical disc apparatus of the present invention has an objective lens for condensing light emitted from a light source on an information recording surface of an optical disc, and is movable in the radial direction of the optical disc, and the optical pickup An optical disc apparatus comprising: an objective lens actuator that can move the objective lens in a focus direction, a tracking direction, and a tilt direction; and a control unit that controls driving of the optical pickup and the objective lens actuator. The control unit performs focus servo control in a state where the optical pickup is disposed at a predetermined position to measure a drive control amount for driving the objective lens in a focus direction, and based on the measured drive control amount The tilt of the objective lens in the tilt direction is changed according to the surface vibration period of the optical disc. It acquires the tilt control condition is characterized by performing the face shake correction tilt control that.

  According to this configuration, since the configuration is such that the radial skew of the surface runout disk is corrected by the control operation of the control unit (deterioration of jitter is reduced), the conventionally used objective lens actuator has been applied to the optical disc apparatus. Even if it is a case, the performance deterioration by a surface runout disk can be suppressed. That is, it is possible to provide an optical disc apparatus capable of appropriately correcting the radial skew of the surface runout disc while suppressing the manufacturing burden (cost increase) such as component management.

  In addition, even when the optical disk device is configured to be compatible with a plurality of types of optical disks, because it is configured to correct the radial skew of the surface shake disk by the control operation by the control unit (to reduce the deterioration of jitter), In any of the optical discs, it is possible to suppress the performance deterioration due to the surface runout disc. In other words, it is possible to provide an optical disc apparatus capable of appropriately correcting the radial skew of a surface wobbling disc in a case where a plurality of types of optical discs can be handled.

  In the optical disk apparatus having the above configuration, it is preferable that the control unit generates a signal for performing the surface shake correction tilt control so as to be synchronized with a focus drive signal used for performing the focus servo control. According to this configuration, it is easy to perform tilt control that varies the tilt in the tilt direction of the objective lens in accordance with the surface vibration period of the optical disc.

  In the optical disc apparatus configured as described above, the control unit may perform the surface shake correction tilt control when a fluctuation range of the drive control amount in one rotation period of the optical disc exceeds a predetermined threshold. In this configuration, the control unit may perform tilt control different from the surface shake correction tilt control when the fluctuation range of the drive control amount is equal to or less than the predetermined threshold.

  In the optical disk apparatus having the above configuration, it is preferable that the predetermined position is a position on the outer peripheral side of the optical disk. Since the surface runout amount of the surface runout disc increases on the outer periphery side of the optical disc, according to this configuration, accurate runout information can be easily obtained from the drive control amount for driving the objective lens in the focus direction, and the surface runout disc radial can be obtained. It is easy to correct the skew appropriately.

  In the optical disk apparatus having the above configuration, the predetermined position may be a plurality of positions. According to this configuration, it is possible to vary the tilt control condition (inclination of the objective lens) for surface shake correction in accordance with the position of the optical pickup in the radial direction, and the radial skew of the surface shake disk can be more accurately determined. It becomes possible to correct to.

  In the optical disk apparatus having the above configuration, the rotation control of the optical disk is performed so that the linear velocity is constant, and the period of the signal for performing the tilt control for the surface vibration disk may be changed depending on the position of the optical pickup. .

  According to the present invention, since the radial skew of a surface runout disc can be corrected appropriately, the reproduction performance and recording performance of the optical disc can be improved.

1 is a block diagram showing a configuration of an optical disc device according to a first embodiment. The top view for demonstrating the optical pick-up with which the optical disk apparatus of 1st Embodiment is equipped. 1 is a schematic perspective view showing a configuration of an objective lens actuator provided in the optical disc apparatus of the first embodiment. 1 is a schematic perspective view showing a coil configuration of an objective lens actuator provided in the optical disc apparatus according to the first embodiment. 6 is a flowchart showing a flow of tilt control operation for correcting a radial skew of a surface runout disc in the optical disc apparatus according to the first embodiment. Schematic diagram for explaining the surface runout amount Graph showing the relationship between surface runout and radial skew Schematic diagram for explaining the tilt drive signal synchronized with the focus drive signal The graph which shows an example of the relationship between the position of an optical pick-up, and the rotation frequency of an optical disk in a CLV control system FIG. 3 is a schematic diagram illustrating a state in which surface shake correction tilt control of an objective lens is performed by a tilt drive signal synchronized with a focus drive signal in the optical disc apparatus according to the first embodiment. A flowchart showing an operation flow of tilt control of the objective lens in the optical disc apparatus of the second embodiment. Schematic diagram for explaining problems that occur when playing or recording a surface runout disc

  Hereinafter, embodiments of an optical disk device of the present invention will be described in detail with reference to the drawings.

1. First Embodiment (Configuration of Optical Disk Device)
FIG. 1 is a block diagram showing the configuration of the optical disc apparatus according to the first embodiment. FIG. 2 is a plan view for explaining the optical pickup provided in the optical disc apparatus according to the first embodiment. In FIG. 2, the optical disk D is indicated by a broken line, but this optical disk D is positioned above the optical pickup 4 (the front side in FIG. 2).

  As shown in FIG. 1, the optical disc apparatus 1 of the first embodiment has a spindle motor 2. The spindle motor 2 is connected to a turntable 3 (see FIG. 2) whose output shaft 2a holds the optical disk D in a detachable manner. For this reason, the optical disk D held on the turntable 3 can be rotated by driving the spindle motor 2. The drive control of the spindle motor 2 is performed using a spindle motor drive circuit 11. In the optical disc apparatus 1, the rotation of the optical disc D is controlled so that the linear velocity is constant (CLV (Constant Linear Velocity) control).

  In addition, the optical disc apparatus 1 is provided with an optical pickup 4 used for reading information recorded on the optical disc D and writing information on the optical disc D. The optical pickup 4 has a light source (not shown) composed of, for example, a laser diode. The drive control of the light source included in the optical pickup 4 is performed using the laser drive circuit 12.

  The type of wavelength of the light (laser light) emitted from the light source corresponds to the type of optical disc D that can be reproduced or recorded by the optical disc device 1 (single case or plural cases are assumed). As appropriate. For example, when the optical disc apparatus 1 supports three types of optical discs of BD, DVD, and CD, a laser beam having a wavelength of 405 nm (for BD), a laser beam having a wavelength of 650 nm (for DVD), and 780 nm. A laser beam (for CD) having a band wavelength can be emitted.

  The optical pickup 4 receives the reflected light reflected by the information recording surface RS and the objective lens 41 that condenses the light emitted from the light source on the information recording surface RS (see FIG. 1) of the optical disc D. (Not shown). The light receiving unit functions as a photoelectric conversion unit that converts the received optical signal into an electrical signal. In addition, the optical pickup 4 is appropriately provided with various lenses, aberration correction means for correcting aberrations, and the like.

  In the first embodiment, the optical pickup 4 is configured to have only one objective lens 41. However, the present invention is not limited to this configuration, and when the optical disc apparatus 1 is provided so as to be compatible with a plurality of types of optical discs D, it is a matter of course that a configuration having a plurality of objective lenses can be used depending on the type of the optical disc D. I do not care.

  The optical pickup 4 is slidable along two guide rails 10 extending in a direction substantially parallel to the radial direction (radial direction) of the optical disc D. The optical pickup 4 can be moved in the radial direction by driving a thread motor (not shown). As a result, the optical pickup 4 freely moves in the radial direction, and can arbitrarily access any address of the optical disc D. The sled motor drive control is performed using a sled motor drive circuit 13.

  The objective lens 41 of the optical pickup 4 can be moved in a focus direction, a tracking direction, and a tilt direction by a so-called wire support type objective lens actuator (shown in FIGS. 3 and 4 to be described later). The focus direction is a direction substantially orthogonal to the information recording surface RS of the optical disc D. The tracking direction is a direction substantially parallel to the radial direction (radial direction) of the optical disc D. The tilt direction is a direction around the axis orthogonal to the focus direction and the tracking direction.

  Here, the configuration of the objective lens actuator 5 provided in the optical pickup 4 will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic perspective view showing the configuration of the objective lens actuator provided in the optical disc apparatus of the first embodiment. FIG. 4 is a schematic perspective view showing the coil configuration of the objective lens actuator provided in the optical disc apparatus according to the first embodiment.

  The objective lens actuator 5 includes a ferromagnetic act base 51 mounted on a pickup base that constitutes the optical pickup 4, and a lens holder 52 that holds the objective lens 41. When the optical pickup has a plurality of objective lenses, the lens holder may be configured to hold a plurality of objective lenses.

  On the act base 51, a pair of permanent magnets 53 are erected in a tangential direction (a direction perpendicular to both the focus direction F and the tracking direction T) so as to sandwich the lens holder 52 therebetween. . In the objective lens actuator 5, a yoke 57 obtained by bending the act base 51 is magnetically attached to the outer surface side of the permanent magnet 53 in order to efficiently use the magnetic flux generated by the permanent magnet 53. It has become.

  One end of each of the wires 54 is fixed to the lens holder 52, three wires on one side and six wires on each side. The other end of each wire 54 is fixed to a circuit board 55 that is fixedly arranged with respect to the act base 51, whereby the lens holder 52 is cantilevered by the wire 54 and is shaken with respect to the act base 51. It is possible to move.

  In addition, a through hole (not shown) is formed in a portion of the act base 51 that contacts the lower side of the lens holder 52 so that light emitted from the light source is incident on the objective lens 41 held by the lens holder 52. It has become. A gel holder 56 to which the circuit board 55 is fixed is fixedly disposed on the act base 51. The wire 54 whose one end is fixed to the lens holder 52 is fixed to the circuit board 55 with the other end being inserted into the gel material filling portion 56 a of the gel holder 56. The gel material filled in the gel material filling portion 56 a serves to attenuate the vibration generated in the wire 34 in accordance with the driving of the objective lens actuator 5.

  Further, the lens holder 52 includes a focus coil 521 (see FIG. 4) disposed so as to surround the optical axis of the objective lens 41 along the inner side wall of the lens holder 52, and two outer side walls (permanently). Four track coils 522 (see FIGS. 3 and 4) arranged two by two at symmetrical positions on the side wall facing the magnet 53, and inside the lens holder 52 and below the focus coil 521, Two tilt coils 523 (see FIG. 4) arranged symmetrically in the tracking direction T are attached. Each of these three types of coils 521 to 523 is wound in a substantially rectangular shape, and current is supplied from the circuit board 55 via the wire 34.

  When a current flows through the focus coil 521, the objective lens 41 moves in the focus direction F together with the lens holder 52 in accordance with the direction in which the current flows and the magnitude of the current due to the electromagnetic action with the magnetic field generated by the permanent magnet 53. To do. Similarly, when a current flows through the track coil 522, the objective lens 41 moves in the tracking direction T together with the lens holder 52 according to the direction and size.

  In addition, when a current flows through the tilt coil 523, the objective lens 41, along with the lens holder 52, is an axis that is orthogonal to the focus direction F and the tracking direction T (indicated by a broken line in FIG. 3). It rotates in the rotation direction R. By this rotation, the inclination (tilt) of the objective lens 41 in the radial direction can be adjusted.

  Returning to FIG. 1, the reproduction RF signal generation circuit 14 generates a reproduction RF signal based on the signal output from the light receiving unit of the optical pickup 4, and outputs the generated reproduction RF signal to the control device 6. The FE signal generation circuit 15 generates a focus error signal (FE signal) by a known method such as an astigmatism method based on a signal output from the light receiving unit of the optical pickup 4, and the generated FE signal is generated. Output to the control device 6. Further, the TE signal generation circuit 16 uses a known method such as a PP (Push-Pull) method or a DPP (Differential Push-Pull) method based on a signal output from the light receiving unit of the optical pickup 4. (TE signal) is generated, and the generated TE signal is output to the control device 6.

  The control device 6 is constituted by a microcomputer, and appropriately controls each part constituting the optical disc device 1 and appropriately executes arithmetic processing necessary for the control. The control device 6 includes a storage unit 61 including a ROM 611 (Read Only Memory) and a RAM 612 (Random Access Memory). The ROM 611 stores various parameters and operation programs necessary for the control device 6 to perform various processes. The RAM 612 is used as a work area and a storage area for various information.

  The control device 6 includes a signal processing unit 62. The signal processing unit 62 decodes the reproduction RF signal, and the reproduction data is output to the outside via the interface 7. Further, the signal processing unit 62 performs processing for encoding data input from the outside via the interface 7. The encoded data is written (recorded) on the optical disc D by operating the optical pickup 4 under the control of the control device 6.

  The control device 6 includes a servo processing unit 63. The servo processing unit 63 generates a focus drive signal based on the FE signal in order to perform focus servo control, or generates a tracking drive signal based on the TE signal in order to perform tracking servo control. The control device 6 controls the objective lens actuator 5 via the objective lens actuator drive circuit 17 according to the obtained focus drive signal and tracking drive signal, and executes operations necessary for servo control.

  The servo processing unit 63 also generates a control signal for driving a sled motor that is used to move the optical pickup 4 in the radial direction. The control device 6 controls the sled motor via the sled motor drive circuit 13 according to the generated control signal.

  The control device 6 includes a tilt processing unit 64. The tilt processing unit 64 performs processing necessary for controlling the tilt of the objective lens 41 in the tilt direction by the objective lens actuator 5. In the optical disc apparatus 1 according to the first embodiment, the processing executed by the tilt processing unit 64 can suppress deterioration in reproduction quality and recording quality even when the optical disc 1 is a surface shake disc. . Hereinafter, an operation of reproducing and recording the optical disc D by correcting the radial skew of the surface shake disc by tilt control of the tilt direction of the objective lens 41 in the optical disc apparatus 1 of the first embodiment will be described.

(Tilt control to correct radial skew of surface runout disc)
FIG. 5 is a flowchart showing an operation flow of tilt control (surface shake correction tilt control) for correcting the radial skew of the surface shake disc in the optical disc apparatus of the first embodiment. Hereinafter, a description will be given with reference to FIG.

  In the following description, “surface deflection” is defined as shown in FIG. That is, the “surface runout amount” is a certain radial direction in the case where the target optical disc D and an ideal optical disc REF (shown by a one-dot chain line) having no surface runout are arranged with the rotation center O aligned. This is the distance difference between the disk surfaces at the position (distance difference in the focus direction). The amount of surface fluctuation varies depending on how the certain position is determined. Further, the surface shake may occur on the upper side (plus direction) of the ideal optical disk REF or on the lower side (minus direction). In FIG. 6, a broken line optical disk D indicates a state in which the solid line optical disk D is rotated by 180 °.

  The controller 6 controls the spindle motor 2 to rotate the optical disk D before reproducing the optical disk D (may be read as recording; hereinafter referred to as “reproduction (recording)” in the same meaning). At the same time, the objective lens actuator 5 is used to start drive control in the focus direction of the objective lens 41 (that is, focus servo control) in accordance with the focus drive signal (step S1).

  Further, the control device 6 drives the sled motor to move the optical pickup 4 to a predetermined position (stored in the storage unit 61) (step S2). As the predetermined position, a certain position on the outer peripheral side of the optical disc D is selected as a preferred form. This is because the surface shake amount is larger on the outer peripheral side of the optical disc D, and tilt control conditions described later can be easily obtained accurately.

  When the optical pickup 4 is disposed at a predetermined position, the control device 6 (tilt processing unit 64) measures a drive voltage (hereinafter referred to as a focus drive voltage) when the objective lens 41 is driven in the focus direction according to the focus drive signal. Is started (step S3). The focus drive voltage is measured at predetermined time intervals, and the measured value is stored in the storage unit 61 as appropriate. The focus drive voltage is an example of the drive control amount of the present invention. In addition, the drive control amount of the present invention may be a current or the like.

  The control device 6 (tilt processing unit 64) acquires a tilt control condition for correcting the radial skew of the optical disc D based on the measured focus drive voltage (step S4). Specifically, the maximum value and the minimum value of the focus drive voltage in one rotation period of the optical disc D are obtained, and the surface shake information (information on the surface shake state) of the optical disc D is acquired based on the maximum value and the minimum value. . Then, the tilt control condition is acquired based on the acquired surface shake information.

  The storage unit 61 of the optical disc device 1 uses a plurality of types of optical discs D whose surface shake amounts are known in advance, and a focus drive when the optical pickup 4 is disposed at a predetermined position (same as the predetermined position in step S2). The result (table) of examining the relationship between the voltage and the surface shake amount of the optical disc D is stored. For this reason, the surface shake information of the optical disc D can be obtained from the maximum value and the minimum value of the focus drive voltage in one rotation period of the optical disc D. Then, as shown in FIG. 7, if the surface shake amount is known, the radial skew of the optical disc D is obtained. Therefore, the objective lens 41 is adjusted in order to correct the radial skew based on the surface shake information described above. Whether or not to tilt (tilt control condition) can be acquired. The storage unit 61 may store a table indicating the relationship between the focus drive voltage and the radial skew instead of storing a table indicating the relationship between the focus drive voltage and the surface shake amount of the optical disc D.

  The direction in which the objective lens 41 is inclined may be set so that the optical axis of the objective lens 41 and the information recording surface RS of the optical disc D are substantially orthogonal to each other. Tilt to. Note that the radial skew generation direction can be determined from the value of the focus drive voltage.

  That is, in the optical disc apparatus 1, the position in the focus direction of the objective lens 41 determined on the assumption that the ideal optical disc D without surface shake is reproduced (recorded) is set as the focus reference position, and the focus reference position is set to this focus reference position. The focus drive voltage when the objective lens 41 is disposed is stored as a reference drive voltage. By comparing the reference drive voltage with the measured focus drive voltage, the moving direction of the objective lens 41 is known, so the radial skew generation direction is also known.

  The surface shake cycle is the same as the rotation cycle of the optical disc D, and the objective lens 41 vibrates in the focus direction in accordance with this rotation cycle. For this reason, the inclination of the objective lens 41 that corrects the radial skew when the focus drive voltage becomes the maximum value and the inclination of the objective lens 41 that corrects the radial skew when the focus drive voltage becomes the minimum value are obtained. If control is performed to vary the tilt in the tilt direction of the objective lens 41 in synchronization with the focus drive signal, it is possible to suppress the deterioration of jitter due to the radial skew of the surface shake disc. In other words, step S4 can be said to be a step of acquiring a range in which the tilt of the objective lens 41 is varied so that the radial skew of the optical disc D can be corrected.

  When a tilt control condition (a range in which the tilt of the objective lens 41 is varied) for correcting the radial skew based on the focus drive voltage is acquired, a tilt drive signal is generated based on the acquired tilt control condition to correct surface shake. The optical disk D is reproduced (stored) while performing tilt control (step S5). The tilt drive signal is a signal for performing control to vary the tilt of the objective lens 41 in the tilt direction R (see FIG. 3) so as to correct the radial skew of the optical disc D, and is synchronized with the focus drive signal.

  The tilt drive signal (Ti drive signal) synchronized with the focus drive signal is obtained by, for example, filtering the focus drive signal (Fo drive signal) to obtain a binarized signal as shown in FIG. It can be obtained by synchronizing with The tilt drive signal is generated so that the tilt of the objective lens 41 is changed according to the previously obtained tilt control condition.

  The optical disc apparatus 1 performs CLV control for the rotation of the optical disc D. For this reason, as shown in FIG. 9, the rotational frequency changes depending on the radial position of the optical pickup 4 (the distance from the rotational center of the optical disk D). That is, in the optical disc apparatus 1, the surface shake period varies depending on the position of the optical pickup, and the period of the tilt drive signal synchronized with the focus drive signal also varies. However, in the present embodiment, the manner in which the tilt of the objective lens 41 fluctuates (fluctuation range) in one cycle of the tilt drive signal is constant regardless of the position of the optical pickup 4.

  FIG. 9 is a graph showing an example of the relationship between the position of the optical pickup and the rotation frequency of the optical disc in the CLV control method. FIG. 9 is a diagram showing the relationship when reproducing (recording) at double speed (double the linear velocity of 3.48 m / s).

  FIG. 10 is a schematic diagram illustrating a state in which the surface shake correction tilt control of the objective lens is performed by the tilt drive signal synchronized with the focus drive signal in the optical disc apparatus according to the first embodiment. In FIG. 10, the symbol O is the rotation center of the optical disc D. FIG. 10 shows a state where the optical disc D is moved up and down due to surface deflection.

  As shown in FIG. 10, during reproduction (recording) of the optical disc D, the objective lens 41 is tilted in the same direction as the radial skew generation direction, and the optical axis AX of the objective lens 41 and the information recording surface RS of the optical disc D are approximately. Always kept in an orthogonal relationship. For this reason, even when reproducing (recording) a surface vibration disc, it is possible to reduce the deterioration of jitter caused by the radial skew of the optical disc D.

  By the way, when the optical disc apparatus 1 supports a plurality of types of optical discs, the above-described focus reference position may differ depending on the type of the optical disc. In order to cope with this, when the optical disc apparatus 1 supports a plurality of types of optical discs, the relationship between the above-described reference drive voltage and the focus drive voltage and the surface deflection amount of the optical disc is examined for each optical disc type. The table may be stored in the storage unit 61. As a result, for any optical disc type that can be handled by the optical disc apparatus 1, the radial skew of the optical disc D (generated by the surface shake) can be appropriately corrected to reduce the deterioration of jitter.

2. Second Embodiment (Configuration of Optical Disk Device)
The configuration of the optical disc apparatus of the second embodiment is the same as that of the optical disc apparatus of the first embodiment. For this reason, the same reference numerals are given to portions overlapping with those of the optical disc device 1 of the first embodiment, and the description thereof is omitted.

(Tilt control to correct radial skew of surface runout disc)
The optical disc apparatus of the second embodiment is different from the first embodiment in the control operation when correcting the radial skew of the surface runout disc. Therefore, the optical disc apparatus according to the second embodiment will be described focusing on this point. FIG. 11 is a flowchart illustrating an operation flow of tilt control of the objective lens in the optical disc apparatus according to the second embodiment. Hereinafter, a description will be given with reference to FIG.

  The controller 6 controls the spindle motor 2 to start rotation of the optical disk D before reproducing (recording) the optical disk D, and uses the objective lens actuator 5 to focus the objective lens 41 according to the focus drive signal. Direction drive control (that is, focus servo control) is started (step S11).

  Further, the control device 6 drives the sled motor to move the optical pickup 4 to a first predetermined position (stored in the storage unit 61) (step S12). As this first predetermined position, a certain position on the inner peripheral side of the optical disc D is selected.

  When the optical pickup 4 is disposed at the first predetermined position, the control device 6 changes the tilt in the tilt direction of the objective lens 41 to a plurality of predetermined tilts, and measures a predetermined physical quantity at each tilt (step S13). . The measured predetermined physical quantities are stored in the storage unit 61, respectively. The predetermined physical quantity may be any quantity that can be used as an index of the reproduction quality and / or recording quality of the optical disc D. For example, the amplitude of the RF signal, the amplitude of the TE signal, jitter, and the like are used.

  Next, the control device 6 drives the sled motor to move the optical pickup 4 to a predetermined second predetermined position (stored in the storage unit 61) (step S14). As this second predetermined position, a certain position on the outer peripheral side of the optical disc D is selected.

  When the optical pickup 4 is disposed at the second predetermined position, the control device 6 (tilt processing unit 64) starts measuring the focus drive voltage of the objective lens 41 (step S15). The focus drive voltage is measured at predetermined time intervals, and the measured value is stored in the storage unit 61 as appropriate. The focus drive voltage is an example of the drive control amount of the present invention.

  The control device 6 (tilt processing unit 64) checks whether or not the fluctuation range of the focus drive voltage in one rotation period of the optical disc D exceeds a predetermined threshold (step S16). The fluctuation range of the focus drive voltage is obtained as a difference between the maximum value and the minimum value of the focus drive voltage in one rotation period of the optical disc D. When the fluctuation range of the focus drive voltage is small, it can be determined that the fluctuation amount of the radial skew due to the surface shake of the optical disk D to be reproduced (recorded) is small. In this case, the jitter can be hardly deteriorated without performing control (surface vibration correction tilt control) for changing the tilt in the tilt direction of the objective lens 41 in accordance with the surface vibration period so as to correct the radial skew. . For this reason, in step S16, it is determined whether or not to perform surface shake correction tilt control.

  When the fluctuation range of the focus drive voltage exceeds a predetermined threshold (Yes in step S16), processing is performed so that surface shake correction tilt control is performed. For this reason, processing similar to steps S4 and S5 (see FIG. 5) in the optical disc apparatus 1 of the first embodiment is performed (steps S17 and S18).

  On the other hand, when the fluctuation range of the focus drive voltage does not exceed the predetermined threshold (Yes in step S16), the surface shake correction tilt control is not performed. In this case, the optical disc D may be reproduced without performing tilt control at all. However, even an ideal optical disk without surface deflection or warpage is warped on the optical disk D to some extent when it is rotated at a high speed. In consideration of such points and the like, this embodiment is configured to perform another tilt control.

  That is, when the fluctuation range of the focus drive voltage does not exceed the predetermined threshold (Yes in Step S16), the optical pickup 4 is placed at the second predetermined position in the same manner as in Step S13, and the objective lens 41 is moved. The inclination in the tilt direction is changed to a plurality of predetermined inclinations, and a predetermined physical quantity is measured at each inclination (step S19).

  Based on the measurement results (steps S13 and S19) of the predetermined physical quantity previously performed, optimum tilts in the tilt direction of the objective lens 41 at the first predetermined position and the second predetermined position are obtained (step S20). Then, based on the obtained optimum tilts of the two objective lenses 41, tilt control of the objective lenses is performed to reproduce (record) the optical disc (step S21).

  The tilt control of the objective lens 41 at this time may be a constant angle regardless of the position of the optical pickup 4, or the objective lens 41 may be continuously or stepwise depending on the position of the optical pickup 4. The inclination may be varied. In the former case, for example, an inclination obtained by averaging the two optimum inclinations obtained in step S20 may be adopted as the inclination of the objective lens 41. In the latter case, the inclination of the objective lens 41 at each optical pickup 4 position may be determined by data interpolation using the two optimum inclinations obtained in step S20.

  Also in the optical disc apparatus 1 of the second embodiment, the radial skew of the surface runout disc can be appropriately corrected. Therefore, in the optical disc apparatus according to the second embodiment, as in the optical disc apparatus 1 according to the first embodiment, even when the surface shake disc is reproduced (recorded), deterioration of the quality can be suppressed.

3. Others The optical disk devices of the first embodiment and the second embodiment described above are one embodiment of the present invention, and the optical disk device of the present invention is not limited to the above configuration.

  For example, in the embodiment described above, the optical pickup 4 is arranged at one predetermined position, and the tilt control condition of the objective lens 41 corresponding to the surface deflection disk is obtained. However, the present invention is not limited to this configuration. In other words, the optical pickups 4 may be arranged at a plurality of locations, and conditions for changing the tilt in the tilt direction of the objective lens 41 may be obtained at each position in order to correct the radial skew. With this configuration, the surface shake correction tilt control can be performed under different conditions in accordance with the radial position of the optical pickup, so that the radial skew of the surface shake disk can be corrected more accurately.

  In the embodiment described above, the optical disc apparatus is configured to obtain the tilt control condition corresponding to the surface shake disc every time reproduction (recording) is performed. However, the configuration is not limited to this. That is, for example, when reproducing (recording) the optical disc D having acquired the tilt control condition first, the operation of acquiring the tilt control condition corresponding to the surface shake disc is omitted, and the previously acquired condition is used. Surface shake correction tilt control may be performed. In such a control operation, after acquiring the tilt control condition corresponding to the surface deflection disk, the storage unit 61 (or the optical disk D) stores the condition and the information of the optical disk D that acquired the condition. It becomes possible.

  In the above description, the configuration of the optical disc apparatus 1 is configured such that the rotational frequency of the optical disc D changes depending on the position of the optical pickup 4 (configuration of CLV control). However, the present invention can also be applied to an optical disc apparatus having a configuration in which the rotational frequency of the optical disc D does not change depending on the position of the optical pickup 4 (configuration of constant angular velocity (CAV) control).

  In the above description, the optical disc apparatus is configured to perform reproduction and recording. However, the present invention can also be applied to a case where the optical disc apparatus is an apparatus that can perform only reproduction or recording.

  The present invention is applicable to, for example, an optical disc player and an optical disc recorder.

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 4 Optical pick-up 5 Objective lens actuator 6 Control apparatus 41 Objective lens D Optical disk RS Information recording surface

Claims (7)

An optical pickup having an objective lens for condensing the light emitted from the light source on the information recording surface of the optical disc, and movable in the radial direction of the optical disc;
An objective lens actuator included in the optical pickup and capable of moving the objective lens in a focus direction, a tracking direction, and a tilt direction;
A control unit that controls driving of the optical pickup and the objective lens actuator;
An optical disc device comprising:
The control unit performs focus servo control in a state where the optical pickup is disposed at a predetermined position to measure a drive control amount for driving the objective lens in a focus direction, and an optical disc based on the measured drive control amount An optical disc apparatus characterized in that a tilt control condition for changing a tilt in the tilt direction of the objective lens in accordance with a surface shake period is obtained to perform a surface shake correction tilt control.   The optical disk according to claim 1, wherein the control unit generates a signal for performing the surface shake correction tilt control so as to be synchronized with a focus drive signal used for performing the focus servo control. apparatus.   The said control part performs the said surface shake correction tilt control, when the fluctuation range of the said drive control amount in 1 rotation period of the said optical disk exceeds a predetermined threshold value, Optical disk device.   4. The optical disc apparatus according to claim 3, wherein the control unit performs tilt control different from the surface shake correction tilt control when the fluctuation range of the drive control amount is equal to or less than the predetermined threshold value. .   5. The optical disk apparatus according to claim 1, wherein the predetermined position is a position on the outer peripheral side of the optical disk.   The optical disk apparatus according to claim 1, wherein the predetermined position is a plurality of positions.   7. The optical disk rotation control is performed so that the linear velocity is constant, and the period of a signal for performing the surface shake correction tilt control varies depending on the position of the optical pickup. An optical disk device according to the above.