JP2012009114A - Optical disk device and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device that can suppress an AC tilt that occurs during driving an objective lens in a tracking direction while reducing a design load of an objective lens actuator.SOLUTION: A control part 6 of an optical disk device 1 controls the driving in a tilt direction of an objective lens by a tilt drive signal synchronized with a tracking drive signal for controlling the driving in a tracking direction of the objective lens (included in an optical pickup 4) when performing at least either the playback or the recording of an optical disk.

Description

  The present invention relates to an optical disc apparatus used when reproducing information recorded on an optical disc or recording information on an optical disc, and more specifically, suppresses an AC tilt generated in an objective lens actuator included in the optical disc apparatus. It relates to control technology.

  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. Focus servo control refers to control performed so that the focal position of the objective lens always matches the information recording surface, and tracking servo control refers to a light spot condensed by the objective lens that always follows the track of the optical disk. It refers to the control performed.

  As the configuration of the objective lens actuator, a so-called wire type has been conventionally known (see, for example, Patent Documents 1 and 2). This wire-type objective lens actuator has a configuration in which a lens holder that holds an objective lens is cantilevered so as to be swingable by a wire having one end fixed to a fixed portion. The lens holder can be moved in the focus direction and the tracking direction by a magnetic circuit including a coil fixed to the lens holder and a magnet fixed to the base constituting the objective lens actuator. The

  In the wire type objective lens actuator configured as described above, the center of gravity of the lens holder and the point of action of the driving force generated when the lens holder is driven in the tracking direction are shifted in the height direction (focus direction). For this reason, it is conventionally known that AC tilt due to rolling occurs (see, for example, Patent Document 1). When the AC tilt is generated and the objective lens is tilted, an optical aberration is generated, which causes a problem because the reproduction quality and the recording quality of the optical disc apparatus are deteriorated.

  Conventionally, the above-mentioned AC tilt is suppressed by optimizing the objective lens actuator design, for example, optimizing the balance design of the lens holder and optimizing the rolling frequency (torsional resonance frequency). . Further, as shown in Patent Literature 1, a tilt coil (a coil for tilting the objective lens) is detected by detection control means for detecting the radial tilt (or radial direction) of the objective lens (or information on the tilt of the objective lens). ) To reduce the AC tilt.

JP 2003-22552 A JP 2007-305243 A

  However, 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, it is not easy to optimize the balance design of the lens holder so that the above-mentioned AC tilt can be suppressed when reproducing any optical disk.

  In recent years, the rotational frequency of optical discs tends to increase, and it is not easy to optimize the rolling frequency so as to suppress the above-mentioned AC tilt. That is, it is not easy to prevent the above-described AC tilt from occurring by optimizing the design of the objective lens actuator.

  Further, in the configuration disclosed in Patent Document 1, it is necessary to monitor the tilt of the objective lens by the detection control means, for example, during reproduction of the optical disc. For this reason, a device for detecting the tilt of the objective lens is required, which is disadvantageous in terms of cost. In addition, even when a new device for detecting the tilt of the objective lens is not introduced, the control of the tilt of the objective lens is performed by supplying a correction current to the tilt coil while detecting information on the tilt of the objective lens. Considering this burden, further ingenuity is desired.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc apparatus capable of suppressing AC tilt generated when driving an objective lens in a tracking direction while reducing the design burden of the objective lens actuator. Another object of the present invention is to provide a method of controlling an optical disc apparatus that can suppress an AC tilt generated when the objective lens is driven in the tracking direction with a control operation as simple as possible.

  In order to achieve the above object, the optical disc apparatus of the present invention condenses the light emitted from the light source on the information recording surface of the optical disc by the objective lens and receives the reflected light reflected by the optical disc at the light receiving unit. A pickup, 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; and driving the objective lens actuator based on a signal output from the light receiving unit. A tracking drive that controls driving of the objective lens in a tracking direction when performing at least one of reproduction and recording of the optical disk. The objective lens is tilted by a tilt drive signal synchronized with the signal. It is characterized by controlling the driving of the direction.

  The AC tilt is generated by driving the objective lens in the tracking direction by the tracking drive signal. In this regard, in this configuration, the tilt drive signal that controls the drive of the objective lens in the tilt direction is synchronized with the tracking drive signal that causes the AC tilt. Given to cancel the tilt. For this reason, according to this configuration, it is possible to suppress the AC tilt that occurs when the objective lens is driven in the tracking direction. Since the AC tilt is suppressed by driving control in the tilt direction, the design burden of the objective lens actuator can be reduced.

  In the optical disk apparatus configured as described above, rotation control of the optical disk is performed so that the linear velocity is constant, and the control unit changes the setting condition of the tilt drive signal according to the position of the optical pickup that moves in the radial direction of the optical disk. It is good as well.

  When the rotation control of the optical disk is controlled so that the linear velocity is constant, the rotation frequency of the optical disk changes depending on the position of the optical pickup. Since the amount of AC tilt generated depends on the frequency, appropriate AC tilt suppression is achieved by changing the setting condition of the tilt drive signal according to the position of the optical pickup (that is, depending on the rotation frequency of the optical disk) as in this configuration. Is possible.

  Thus, in the configuration in which the setting condition of the tilt drive signal is changed depending on the position of the optical pickup, the control unit turns off the optical pickup before starting at least one of reproduction and recording of the optical disc. Determining the optimum setting condition of the tilt drive signal based on a predetermined physical quantity serving as an index of at least one of reproduction quality and recording quality at each of the plurality of positions. When obtaining the optimum setting condition of the tilt drive signal at each position of the optical pickup based on the plurality of optimum setting conditions of the tilt drive signal, and performing at least one of reproduction and recording of the optical disc Includes the optimum setting of the tilt drive signal at each position of the optical pickup previously obtained. Based on the conditions, it may control the driving of the tilting direction of the objective lens.

  In the optical disk apparatus having the above configuration, the control unit is a predetermined physical quantity that serves as an index of at least one of reproduction quality and recording quality before starting at least one of reproduction and recording of the optical disk. It is preferable to determine the optimum setting condition of the tilt drive signal based on the above. According to this configuration, by determining the optimum setting condition of the tilt drive signal before the start of reproduction and / or recording of the optical disc, the drive control in the tilt direction of the objective lens can be performed thereafter according to the determined condition. The control operation is not complicated.

  In the optical disk apparatus having the above configuration, the control unit may read data from a storage unit in which the setting conditions of the tilt drive signal are stored in advance, and control driving of the objective lens in the tilt direction. According to this configuration, AC tilt can be suppressed while shortening the time required to start reproduction or recording of the optical disk.

  In order to achieve the above object, the optical disk apparatus control method of the present invention condenses the light emitted from the light source on the information recording surface of the optical disk by the objective lens and receives the reflected light reflected by the optical disk. And 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, and a reproduction quality And acquiring an optimum setting condition of the tilt drive signal synchronized with the tracking drive signal for controlling the driving of the objective lens in the tracking direction based on a predetermined physical quantity serving as an index of at least one of recording quality and recording quality; , Tilted according to the optimum setting conditions acquired previously. By Eve signal, it is characterized by comprising the steps of: performing a tilting direction of the drive control of the objective lens.

  According to the control method of the optical disk apparatus of this configuration, since the tilt drive signal for controlling the drive of the objective lens in the tilt direction is synchronized with the tracking drive signal that causes the AC tilt, the tilt drive signal is It is given to cancel the tilt of the objective lens due to the tilt. Since the drive control in the tilt direction of the objective lens by the tilt drive signal is performed according to the conditions determined in advance, the control operation is not complicated.

  According to the present invention, it is possible to reproduce and record an optical disc while suppressing the AC tilt generated when the objective lens is driven in the tracking direction, so that the reproduction quality and the recording quality can be improved. Further, since the AC tilt can be suppressed by the control operation, a so-called wire type objective lens actuator can be easily designed.

A block diagram showing a configuration of an optical disc apparatus according to the present embodiment The top view for demonstrating the optical pick-up with which the optical disk apparatus of this embodiment is equipped Schematic perspective view showing the configuration of an objective lens actuator provided in the optical disc apparatus of the present embodiment The schematic perspective view which shows the structure of the coil with which the objective lens actuator of this embodiment is provided. The graph which shows the characteristic of the AC tilt generate | occur | produced when driving the objective lens in a tracking direction in the optical disk apparatus of this embodiment. The schematic diagram which shows a mode that a lens holder rolls in the optical disk apparatus of this embodiment, when driving an objective lens in a tracking direction. A flowchart showing a control operation for suppressing AC tilt in the optical disc apparatus of the present embodiment. A flowchart showing a control operation for determining an optimum setting condition of a tilt drive signal at a predetermined position in the optical disc apparatus of the present embodiment.

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

(Configuration of optical disk device)
FIG. 1 is a block diagram showing the configuration of the optical disc apparatus of the present embodiment. FIG. 2 is a plan view for explaining the optical pickup provided in the optical disc apparatus of the present embodiment. In FIG. 2, the optical disk D is indicated by a broken line, but the optical disk D is positioned above the optical pickup 4 (front side in FIG. 2).

  As shown in FIG. 1, the optical disc apparatus 1 of this 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. Corresponding to the type of optical disc D that can be reproduced and recorded by the optical disc apparatus 1, the type of wavelength of light (laser light) emitted from the light source is appropriately determined. For example, when the optical disc apparatus 1 is compatible with three types of optical discs of BD, DVD, and CD, a laser beam having a wavelength of 405 nm, a laser beam having a wavelength of 650 nm, and a laser beam having a wavelength of 780 nm are emitted. Possible configuration. The drive control of the light source included in the optical pickup 4 is performed using the laser drive circuit 12.

  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 is a photoelectric conversion unit that converts a 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 present embodiment, the optical pickup 4 is configured to have only one objective lens 41, but may of course be configured to have a plurality of objective lenses that are selectively used depending on the type of the optical disc D.

  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 can freely move in the radial direction and can appropriately 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 included in the optical pickup 4 can be moved in a focus direction, a tracking direction, and a tilt direction by a so-called wire-type objective lens actuator (shown in FIGS. 3 and 4 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. 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 present embodiment. FIG. 4 is a schematic perspective view showing a configuration of a coil provided in the objective lens actuator of the present 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. .

  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 erected on the act base 51, whereby the lens holder 52 is cantilevered by the wire 54 and swings with respect to the act base 51. It is possible.

  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. Further, a gel holder 56 is provided in parallel with the circuit board 55, and the wire 54 whose one end is fixed to the lens holder 52 is partially inserted into the gel material filling portion 56 a of the gel holder 56, The other end is fixed to the circuit board 55. 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 arranged symmetrically are attached. These coils 521 to 523 are all wound in a substantially rectangular shape, and a current is supplied 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 executes control processing according to operations to be executed by each unit constituting the optical disc device 1, and executes arithmetic processing necessary for 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 necessary 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 performs servo control by controlling the objective lens actuator 5 via the objective lens actuator drive circuit 17 based on the obtained focus drive signal and tracking drive signal.

  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 control condition setting unit 64. The tilt control condition setting unit 64 is a tilt drive signal for suppressing AC tilt (due to the rolling characteristics of the objective lens actuator 5) that occurs when the objective lens 41 is driven in the tracking direction T by the objective lens actuator 5. Set the conditions. The tilt drive signal here is a signal for controlling the driving of the objective lens 41 in the tilt direction. The control device 6 performs drive control in the tilt direction of the objective lens actuator 5 via the objective lens actuator drive circuit 15 based on the tilt drive signal set by the tilt control condition setting unit 64.

(AC tilt suppression control)
Next, details of a control operation for suppressing AC tilt (generated when the objective lens 41 is driven in the tracking direction T) in the optical disc apparatus 1 configured as described above will be described.

  First, an AC tilt generated when the objective lens 41 is driven in the tracking direction T in the objective lens actuator 5 provided in the optical disc apparatus 1 will be briefly described with reference to FIGS. 5 and 6. FIG. 5 is a graph showing the characteristics of the AC tilt generated when the objective lens is driven in the tracking direction in the optical disc apparatus of the present embodiment. FIG. 6 is a schematic diagram showing how the lens holder rolls when the objective lens is driven in the tracking direction in the optical disc apparatus of the present embodiment.

  FIG. 5 shows the relationship between the drive frequency and the tilt angle of the objective lens 41 when the objective lens 41 (held by the lens holder 52) is displaced by a predetermined amount in the tracking direction T. As shown in FIG. 5, it can be seen that the amount of AC tilt generated depends on the frequency and is particularly large in a specific frequency range. It can also be seen that the amount of AC tilt generated varies depending on the position of the objective lens 41 (lens holder 52) in the focus direction F. 5A shows a state in which the objective lens 41 is offset by a predetermined amount in the direction away from the optical disc D along the focus direction F, and FIG. 5B shows the objective lens 41 not offset in the focus direction F. (C) shows a state in which the objective lens 41 is offset by a predetermined amount in the direction approaching the optical disc D along the focus direction F.

  As shown in FIG. 6, the center of gravity G of the lens holder 52 that holds the objective lens 41 and the point of action f of the driving force generated when the lens holder 52 is driven in the tracking direction T are misaligned. When the objective lens 41 (lens holder 52) is driven in the tracking direction T, rolling occurs and AC tilt occurs. In the optical disc apparatus 1 of the present embodiment, as shown in FIG. 5, as the height of the objective lens 41 (lens holder 52) in the focus direction F increases, the positional deviation between the center of gravity G and the action point f increases. Therefore, the amount of AC tilt generated by the above is increased.

  In the state where the AC tilt is largely generated, optical aberration is generated, so that the reproduction quality of the optical disc D and the recording quality onto the optical disc D are deteriorated. For this reason, the optical disc apparatus 1 of the present embodiment is configured to control the drive of the objective lens 41 in the tilt direction by the tilt drive signal to suppress the AC tilt and suppress the deterioration of the reproduction quality and the like.

  The direction in which the objective lens 41 can be tilted by the objective lens actuator 5 and the direction in which the objective lens 41 is tilted by the AC tilt generated when the objective lens 41 is driven in the tracking direction T are both the focus direction and the tracking. The direction around the axis perpendicular to the direction. For this reason, the AC tilt can be suppressed by controlling the tilt direction of the objective lens 41 by the objective lens actuator 5 so that the objective lens is tilted in the opposite direction to the tilt by the AC tilt.

  FIG. 7 is a flowchart showing a control operation for suppressing AC tilt in the optical disc apparatus of the present embodiment. The AC tilt suppression control of the optical disc apparatus 1 will be described with reference to FIG.

  The control device 6 (tilt control condition setting unit 64) of the optical disc apparatus 1 determines a setting condition of a tilt drive signal for suppressing AC tilt before starting reproduction or recording of the optical disc D. Specifically, first, rotation of the optical disk D is started and focus servo control is started (step S1). Next, the sled motor is driven to move the optical pickup 4 to a predetermined first predetermined position (stored in the storage unit 61) (step S2). The first predetermined position is a certain position on the inner peripheral side of the optical disc D, for example.

  When the optical pickup 4 is disposed at the first predetermined position, an operation for determining the optimum setting condition of the tilt drive signal at that position is performed (step S3). The operation for determining the optimum setting condition of the tilt drive signal is performed according to the flowchart shown in FIG.

  Here, with reference to FIG. 8, the control operation performed for the tilt control condition setting unit 64 to determine the optimum setting condition of the tilt drive signal in a state where the optical pickup 4 is disposed at the first predetermined position will be described. . When the optical pickup 4 is disposed at the first predetermined position (at this time, the tracking servo control operation is started), the drive control in the tilt direction of the objective lens 41 is started by the tilt drive signal synchronized with the tracking drive signal. (Step S31).

  The tilt drive signal setting conditions used here (for example, the signal amplitude) may be the conditions stored in the storage unit 61 in advance. Further, the tilt drive signal synchronized with the tracking drive signal is given so as to cancel the tilt (AC tilt) caused by rolling that occurs when the objective lens 41 is driven in the tracking direction T.

  A predetermined physical quantity (for example, RF signal amplitude, jitter, Itop (the upper limit value of the eye pattern) that can be used as an index of reproduction quality and / or recording quality in a state where the drive control of the objective lens 41 in the tilt direction is performed by the tilt drive signal. ) Etc.) is acquired (step S32). The acquired physical quantity is stored in the storage unit 61.

  When the predetermined physical quantity is acquired, the tilt drive signal setting condition (for example, signal amplitude) is changed, and the drive control in the tilt direction of the objective lens 41 by the tilt drive signal synchronized with the tracking drive signal is performed as in step S31. Start (step S33). Then, similarly to step S32, a predetermined physical quantity that can be used as an index of reproduction quality and / or recording quality is acquired (step S34), and the acquired physical quantity is stored in the storage unit 61.

  Next, it is confirmed whether or not the setting condition of the tilt drive signal has been changed a predetermined number of times (for example, three times) (step S35). When the number of times of changing the setting condition is not a predetermined number (No in step S35), the process returns to step S33, and the operations after step S33 are performed again. On the other hand, when the set condition is changed a predetermined number of times (Yes in step S35), the reproduction quality and the recording quality are determined based on the acquired predetermined physical quantity and the setting condition (for example, signal amplitude) of the tilt drive signal. The condition of the tilt drive signal when is best is obtained (step S36). In obtaining the above-described conditions, for example, calculation using a technique such as curve approximation is performed. Then, the obtained condition is determined as the optimum setting condition of the tilt drive signal at the first predetermined position (step S37).

  As described above, the AC tilt is generated when the lens holder 52 moves in the tracking direction T by the tracking drive signal. For this reason, an RF signal, jitter, and the like can be improved by giving a tilt drive signal synchronized with the tracking drive signal so as to cancel the tilt of the objective lens 41 due to AC tilt.

  The amount of AC tilt generated depends on the frequency when the objective lens 41 is driven in the tracking direction T, as shown in FIG. The optical disc apparatus 1 is controlled so that the rotational frequency of the optical disc D varies depending on the position of the optical pickup 4 in order to perform CLV control of the optical disc D as described above. For this reason, it is preferable to change the condition setting of the tilt drive signal given in synchronization with the tracking drive signal depending on the position of the optical pickup 4 in the radial direction. Considering this point, step S4 and subsequent steps of AC tilt suppression control shown in FIG. 7 are performed.

  When the optimum setting condition of the tilt drive signal at the first predetermined position is determined, the control device 6 drives the sled motor to the optical pickup 4 and a predetermined second predetermined position (stored in the storage unit 61). (Step S4). The second predetermined position is a certain position on the outer peripheral side of the optical disc D, for example. At this time, the optical disk D is rotated and focus servo control is performed.

  When the optical pickup 4 is disposed at the second predetermined position, an operation for determining the optimum setting condition of the tilt drive signal at that position is performed (step S5). The method for determining the optimum setting condition is the same as in the case of the first predetermined position (the operation shown in FIG. 8), and thus detailed description thereof is omitted.

  When the optimum setting conditions of the tilt drive signal at the two positions, the first predetermined position and the second predetermined position, are determined, for example, linear interpolation (an example) is used based on the two optimum setting conditions. Thus, the optimum setting condition of the tilt drive signal at each position of the optical pickup 4 is obtained (step S6).

  In step S6, conditions may be set so that, for example, the setting conditions of the tilt drive signal can be continuously changed as the position of the optical pickup 4 changes. Alternatively, the condition may be set so that the setting condition of the tilt drive signal can be changed step by step every time the position of the optical pickup 4 moves by a predetermined amount.

  Further, the amount of AC tilt generated increases in a specific frequency band as shown in FIG. For this reason, in some cases, the position where the rotational frequency of the optical disk D does not enter the specific frequency band (the position of the optical pickup 4 and the outer peripheral side of the optical disk D often corresponds to such a position. ), The condition may be set so that the tilt drive signal is turned off (this state is also included in the change in the setting condition of the tilt drive signal) instead of performing the linear interpolation.

  When the setting condition of the tilt drive signal is obtained in step S6, the optical disc apparatus 1 determines the tracking drive signal according to the obtained setting condition (the condition is appropriately changed according to the position of the optical pickup 4 (in other words, the rotational frequency of the optical disc D)). The optical disk D is reproduced or recorded while controlling the drive of the objective lens 41 in the tilt direction by the tilt drive signal synchronized with (step S7). Thereby, AC tilt can be suppressed and the reproduction and recording quality of the optical disc D in the optical disc apparatus 1 can be improved.

  By the way, in the optical disc apparatus 1 including the objective lens actuator 5 capable of moving the objective lens 41 in the tilt direction, a predetermined amount obtained in advance (for example, before reproduction of the optical disc D or the like) can be suppressed so as to suppress the influence of the warp of the optical disc D. Control may be performed such that the objective lens 41 is tilted as much as required. Even when such a configuration is adopted, AC tilt suppression control using the tilt drive signal described above is possible. That is, if the tilt drive signal synchronized with the tracking drive signal is superimposed on the signal (DC-like signal) given to suppress the influence of the warp, the tilt control of the objective lens is performed. Good.

(Other)
The optical disc apparatus 1 described above is one embodiment of the present invention, and the optical disc apparatus of the present invention is not limited to the above configuration.

  For example, in the embodiment described above, in order to cope with the fluctuation of the rotation frequency of the optical disc D due to the fluctuation of the position of the optical pickup 4, tilting is performed at two places, the first predetermined position and the second predetermined position. The configuration is such that optimum setting conditions for the drive signal are obtained. The present invention is not limited to this configuration. In other words, the optimum setting condition for the tilt drive signal may be obtained at three or more locations.

  Further, in the embodiment described above, a predetermined number of times is set for obtaining the optimum setting condition of the tilt drive signal when the optical pickup 4 is at a predetermined position (first predetermined position or second predetermined position). Although it was set as the structure which changes conditions, it is not the meaning limited to this. That is, for example, every time a setting condition is changed, a predetermined physical quantity is evaluated, and the setting condition change is terminated at a timing when it is determined that the optimum setting condition is obtained (that is, a setting condition is changed any number of times ) Etc.

  In the embodiment described above, before reproducing or recording the optical disc D, the tilt drive signal setting condition synchronized with the tracking drive signal is obtained using a predetermined physical quantity as an index, and the tilt drive is performed according to the obtained setting condition. The driving control in the tilt direction of the objective lens by the signal is performed. However, the present invention is not limited to this configuration. That is, for example, the optimum setting condition of the tilt drive signal synchronized with the tracking drive signal is acquired in advance by an experiment (the acquisition method can be the same as the operation of FIGS. 7 and 8) and stored in the storage unit 61. The drive control in the tilt direction of the objective lens 41 may be performed by reading out and using the tilt drive signal.

  In addition, the optical disc apparatus 1 of the present embodiment has a configuration in which the rotation frequency of the optical disc D changes depending on the position of the optical pickup 4 (configuration of CLV control). However, the present invention may be applied to a configuration in which the rotation frequency of the optical disc D does not change depending on the position of the optical pickup 4 (configuration of CAV (Constant Angular Velocity) control). In this case, the tilt drive signal setting condition may not be changed depending on the position of the optical pickup 4.

  Further, as a method of controlling the rotation of the optical disc D in the optical disc apparatus, the optical disc D is divided into several zones from the inner periphery, the linear velocity is kept constant in each zone, and the linear velocity is different for each zone. Linear Velocity) method. The present invention is also applicable when this method is used. Even when this method is used, the rotational frequency of the optical disk D changes depending on the position of the optical pickup 4 as in the case of the CLV method, but the method of changing the rotational frequency differs for each zone. Therefore, when this method is used, for example, the processes of steps S2 to S6 in FIG. 7 are performed for each zone so as to obtain the optimum setting of the tilt drive signal at each position of the optical pickup 4. Good.

  In the above embodiment, 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. is there.

  The present invention can be applied 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 (6)

An optical pickup for condensing the light emitted from the light source on the information recording surface of the optical disc by the objective lens, and receiving the reflected light reflected by the optical disc by the light receiving unit;
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 objective lens actuator based on a signal output from the light receiving unit;
An optical disc device comprising:
The control unit tilts the objective lens according to a tilt drive signal synchronized with a tracking drive signal that controls driving of the objective lens in a tracking direction when performing at least one of reproduction and recording of the optical disc. An optical disc apparatus that controls driving in a direction. Optical disk rotation control is performed so that the linear velocity is constant,
The optical disk apparatus according to claim 1, wherein the control unit changes a setting condition of the tilt drive signal according to a position of the optical pickup that moves in a radial direction of the optical disk.   The controller drives the tilt drive signal based on a predetermined physical quantity serving as an index of at least one of reproduction quality and recording quality before starting at least one of reproduction and recording of an optical disc. The optical disc apparatus according to claim 1, wherein an optimum setting condition is determined. The controller is
Before starting at least one of reproduction and recording of an optical disc, the optical pickup is arranged at a plurality of positions, and at least one of reproduction quality and recording quality at each of the plurality of positions An optimum setting condition of the tilt drive signal is determined based on a predetermined physical quantity serving as an index of the tilt drive signal, and the tilt drive signal at each position of the optical pickup is determined based on the determined optimum setting conditions of the plurality of tilt drive signals. Find the optimal setting conditions for
When performing at least one of reproduction and recording of the optical disc, the tilt direction of the objective lens is determined based on the optimum setting condition of the tilt drive signal at each position of the optical pickup obtained previously. 3. The optical disk apparatus according to claim 2, wherein driving is controlled.   3. The optical disc according to claim 1, wherein the control unit reads data from a storage unit in which setting conditions of the tilt drive signal are stored in advance, and controls driving of the objective lens in a tilt direction. apparatus. An optical pickup for condensing the light emitted from the light source on the information recording surface of the optical disc by the objective lens, and receiving the reflected light reflected by the optical disc by the light receiving unit;
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 method for controlling an optical disc device comprising:
Based on a predetermined physical quantity serving as an index of at least one of reproduction quality and recording quality, an optimum setting condition of a tilt drive signal synchronized with a tracking drive signal that controls driving of the objective lens in a tracking direction is acquired. Steps,
Performing drive control in the tilt direction of the objective lens according to the tilt drive signal in accordance with the optimal setting condition acquired previously;
An optical disc apparatus control method comprising:

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