JP2005216442A - Optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device capable of making compact an expander lens for correcting the spherical aberration of a laser beam and its driving mechanism, reducing the number of components, facilitating an assembly process, and reducing component and assembling costs. <P>SOLUTION: This device is provided with an expander lens 15 constituted of first and second lenses 15a and 15b, a first lens holder 21 formed into a cylindrical shape to hold the first lens 15a and having a recessed groove 21d with grease deposited on an outer peripheral surface, a second lens holder 22 formed into a cylindrical shape to hold the second lens 15b and to be fitted to the first lens holder 21, and a driving means constituted of an electromagnetic coil 31 fixed to the second lens holder 22 and a magnet 32 for applying a magnetic field to the electromagnetic coil 31. The second lens holder 22 is slid along the outer peripheral surface of the first lens holder 21 by the driving force of the driving means to change a lens space between the first and second lenses 15a and 15b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical pickup apparatus that records or reproduces data by irradiating an optical disk with laser light, and more particularly to a technique that is useful for an optical pickup apparatus that supports an optical disk having a plurality of recording surfaces.

  For example, when information is recorded or reproduced on an optical disc having a two-layer recording surface, an optical disc through which a laser beam passes when accessing the recording surface of the first layer and when accessing the recording surface of the second layer is used. The distance of the transparent layer is different, and thereby the magnitude of the spherical aberration of the laser light exerted by the passage of the transparent layer is different.

  Therefore, in the optical pickup device for the optical disk as described above, an expander lens in which two lenses are arranged on the optical path from the semiconductor laser to the objective lens is provided, and the distance between these lenses is dynamically changed. Thus, the spherical aberration is corrected by changing the beam diameter.

  In such an optical pickup device, as a conventional configuration for changing the lens interval of the expander lens, for example, a lens holder holding one lens is supported in a slidable state, and a screw hole is formed in the lens holder. Some of them are screwed with a screw shaft and rotated by a motor to move the lens holder in parallel to change the lens interval.

Further, as disclosed in Patent Document 1 and Patent Document 2, a lens holder that individually holds the expander lens is supported in a movable state by a leaf spring, a spiral spring, or the like, and an electromagnetic wave is applied to the lens holder using a coil and a magnet. A configuration has been proposed in which a distance between two lenses is changed by applying a force.
JP 2002-352449 A Japanese Patent Laid-Open No. 2003-16660

  However, the conventional expander lens driving method has a problem in that these components occupy a very large volume in the optical pickup, and the volume of the optical pickup becomes large.

  For example, in a configuration using a screw shaft, the motor occupies a large volume, and in a configuration in which the lens holder is supported by a leaf spring or a spiral spring, the leaf spring or the spiral spring protrudes in the width direction of the lens holder and the space in that portion is larger. Volume is occupied.

  Further, the conventional expander lens driving mechanism has a problem that the number of parts is large, the structure is complicated, and the assembly process is complicated.

  An object of the present invention is to provide an optical pickup device that is compact in size, reduces the number of components, facilitates the assembly process, and can be reduced in size and reduced in component cost and assembly cost. Is to provide.

  In order to achieve the above object, the present invention provides an optical pickup apparatus for recording or reproducing data by irradiating an optical disc with laser light, and has a first lens and a second lens, and changes the distance between these lenses. The expander lens capable of correcting the spherical aberration of the laser light, the first lens holder formed in a cylindrical shape and holding the first lens and allowing the laser light to pass through the inner hollow portion, and the cylindrical shape formed in the above A first lens holder is fitted to the first lens holder so as to hold the second lens and allow laser light to pass through the inner hollow portion and to cover the inner peripheral surface of the cylindrical portion on the outer peripheral surface of the first lens holder. Two lens holders, and driving means for applying a force in the optical axis direction to the first lens holder or the second lens holder by electromagnetic force, and the driving force of the driving means 1 lens holder and the second lens holder has been slid in the optical axis direction and configured such that the lens intervals of the expander lens is changed.

  According to such means, a drive mechanism for the expander lens can be configured very compactly because a motor occupying a large volume, a plate spring or a spiral spring for supporting the lens holder in a movable state is unnecessary. . Furthermore, the number of parts can be reduced and the assembling process can be facilitated as compared with a configuration using a conventional screw shaft or a configuration in which the lens holder is supported by a leaf spring or a spiral spring.

  Desirably, a viscous material (for example, grease) is interposed between the joint surfaces of the first lens holder and the second lens holder. Since the lens holder slides smoothly when the driving means is operated by such a viscous material, the lens interval can be easily adjusted. Further, the lens holder can be stopped substantially at the position when the driving means is inactivated due to the resistance of the viscous body. Therefore, the optical pickup can be operated in a state where the driving means is stopped after the lens interval is adjusted once.

  More preferably, a concave groove for accumulating the viscous material is provided on the joint surface between the first lens holder and the second lens holder. This concave groove keeps the viscous body from stopping, and the amount of viscous body can be prevented from decreasing over time, and the viscous body is attached to the lens holder by the design dimensions such as the width, depth and length of the concave groove. The viscous resistance exerted can be controlled.

  Further, when the second lens holder is configured to be movable, an urging means (for example, a spring spring) for applying an urging force to the second lens holder is provided, and the above-mentioned attachment is performed when the driving means is in an inoperative state. The second lens holder may be returned to the initial position by the biasing means.

  According to such a configuration, since the initial position of the lens holder is fixed, the lens position adjustment process can be performed with a constant operation every time, and the control thereof is easy.

  Desirably, in an optical pickup apparatus that records or reproduces data on or from an optical disc having recording surfaces of at least two layers (for example, the 0th layer and the first layer), the initial position of the second lens holder is 2 It may be set at a position corresponding to the recording surface of one of the two layers.

  According to such a configuration, the accuracy of the assembly position of the lens holder or the dimensional accuracy of the lens holder is required at the time of assembly of the optical pickup, but when the recording layer corresponding to the initial position is used at the time of use. The position of the lens holder can be easily obtained.

  Further, in an optical pickup device that records or reproduces data with respect to an optical disc having at least two layers of recording surfaces, the initial position of the second lens holder is set within a movable range corresponding to the recording surfaces of the two layers. It may be set to a position that is included in and deviates from the position.

  According to such a configuration, the setting margin of the initial position can be increased when assembling the optical pickup, and it is sufficient when high accuracy that cannot be obtained at the time of assembly at the adjustment position of the lens holder is desired during use. I can do it.

  In the optical pickup device that records or reproduces data on or from an optical disc having at least two recording layers, the biasing unit moves the second lens holder in a first direction along the optical axis direction. The initial position of the second lens holder is composed of a first spring that biases and a second spring that biases in the direction opposite to the first direction, and the force of the first spring and the second spring balances. You may set to the intermediate position of the position corresponding to the recording surface of one layer and the position corresponding to the recording surface of the other layer among two layers.

  With such a configuration, the required driving force of the driving means can be made substantially the same when the lens interval is adjusted to correspond to one of the two layers and when the lens interval is adjusted to the other layer. Therefore, a desired adjustment operation can be obtained if the necessary operating characteristics (for example, response characteristics and stability) of the driving means are ensured only at least within this driving force range. Becomes easier.

  As described above, according to the present invention, the drive mechanism of the expander lens that corrects the spherical aberration of the laser light can be made compact, the number of parts can be reduced, and the assembly cost can be reduced. And manufacturing cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a diagram showing a configuration of an optical system of an optical pickup device according to an embodiment of the present invention.

  The optical pickup device 1 according to this embodiment performs reproduction and recording of data by irradiating each recording surface with laser light for a blue-violet laser optical disc having two recording surfaces of a 0th layer and a first layer. Is what you do.

  The optical system mounted on the optical pickup device 1 includes a semiconductor laser 10 as a light emitting unit that outputs a blue-violet laser, a collimator lens 11 that collimates the output laser beam, and servo control of the objective lens 17. Therefore, the diffraction grating 12 that generates a sub beam from the laser light, the polarization beam splitter 13 that separates the traveling wave toward the optical disk and the reflected wave from the optical disk, and the polarization beam splitter 13 function as an optical isolator 1 / 4 wavelength plate 14, an expander lens 15 for correcting the spherical aberration of the laser beam by changing the beam diameter, a rising mirror 16, an objective lens 17 for condensing the laser beam on the recording surface of the optical disc D0, Laser light for servo control of the detection lens 7 and the objective lens 17 for condensing the reflected light separated by the beam splitter 13 The optical element 8, such as a cylindrical lens which gives astigmatism, such as an optical sensor 9 for detecting the reflected light is provided.

  The optical pickup device 1 is configured by assembling the above optical system on a base frame (not shown) of one block. Among each optical system, the collimator lens 11 and the expander lens 15 are assembled to the base frame while being held by a lens holder or the like, and the semiconductor laser 10 and the optical sensor 9 are mounted on the base frame together with the substrate on which these elements are formed. It is fixed.

  Further, the base frame includes a driving device 17k that performs servo control by minutely moving the objective lens 17 in the focus direction, the tracking direction, and the like, and driving that dynamically changes the position of the convex lens 15b of the expander lens 15. A device 30 is provided.

  The expander lens 15 is composed of, for example, a concave lens 15a having a small diameter and a convex lens 15b having a large diameter, and the beam diameters of incident light and outgoing light are changed by changing the distance between the lenses, thereby spherical aberration of the laser light. It is possible to correct.

  FIG. 2 is a perspective view showing a state in which the configuration around the expander lens is broken at the center, and FIG. 3 is a perspective view in which the configuration related to the movable lens in the mechanism of FIG. It is.

  2 and 3, 15a is a fixed concave lens, 15b is a convex lens that is movable, 21 is a first lens holder that holds the concave lens 15a, 22 is a second lens holder that holds the convex lens 15b, and 31 is a first lens holder. An electromagnetic coil 32 fixed to the two-lens holder 22 is a magnet that exerts a magnetic field on the movable range of the electromagnetic coil 31. The traveling wave toward the optical disc travels from the concave lens 15a to the convex lens 15b.

  The first lens holder 21 has a cylindrical shape and allows laser light to pass through the inner cavity portion, and has a concave lens on one end side (traveling wave emission side) so that the central axis of the cylindrical portion and the central axis of the concave lens 15a overlap. 15a is fitted and held.

  On one end side of the lens holder 21, a lens fitting step 21 m in which a lens is fitted by changing the thickness of the cylinder by changing the thickness of the cylinder, and a concave lens 15 a at the opening end are provided on one end side of the lens holder 21. In order to facilitate the insertion, a lens insertion step 21n having an inner diameter that is further increased by one step is provided. In addition, a flange 21 a that protrudes outward is provided on the other end side (traveling wave incident side) of the lens holder 21. The flange 21a has a function of abutting on one end of the second lens holder 22 and limiting a movable range thereof, and a function of fixing the lens holder 21 to the base frame of the apparatus.

  As shown in FIG. 3, a plurality of concave grooves 21d formed in a predetermined width, depth, and length are provided at equal intervals in the circumferential direction on the outer peripheral surface of the cylindrical portion of the lens holder 21. ing. Grease as a viscous material is stored in the concave groove 21d.

  The second lens holder 22 has a cylindrical shape and allows the laser beam to pass through the inner cavity portion. At the same time, a central axis of the cylinder and a central axis of the convex lens 15b are formed on a frame portion 22a formed on one end side (traveling wave emission side). The convex lens 15b is fitted and held so as to overlap with each other. The inner peripheral diameter of the cylindrical portion of the lens holder 22 is formed to be slightly larger than the outer peripheral diameter of the cylindrical portion of the first lens holder 21, and the second lens with the outer peripheral surface of the first lens holder 21 as a guide surface. The first lens holder 21 and the second lens holder 22 are fitted so that the holder 22 can slide in the optical axis direction.

  The cylindrical portion of the second lens holder 22 is provided with an air hole 22b for taking in and out air in a space between the two lenses 15a and 15b. Further, an air hole 22b1 may be provided in the edge frame portion of the lens.

  Further, a fixing step 22c for fixing the electromagnetic coil 31 is provided on the outer peripheral portion of the second lens holder 22, and the electromagnetic coil 31 is fixed to the fixing step 22c.

  The magnet 32 has a width larger than the movable range of the convex lens 15 b and is disposed at a position facing the electromagnetic coil 31. In this embodiment, the two rectangular parallelepiped magnets 32 are arranged so as to face each other with the central axis of the second lens holder 22 interposed therebetween, but a plurality of magnets such as three or four are arranged as electromagnetic coils. You may make it arrange | position equally in the circumferential direction of 31. Alternatively, a cylindrical magnet may be arranged so as to surround the electromagnetic coil 31.

  As described above, according to the optical pickup device 1 of this embodiment, the optical disk having a plurality of recording surfaces using the objective lens 17 having a large numerical aperture by the expander lens 15 that corrects the spherical aberration of the laser light. Even when data is recorded / reproduced, a small light spot is recorded by correcting the spherical aberration by adjusting the lens interval of the expander lens 15 by passing a current through the electromagnetic coil 31 corresponding to the recording surface of each layer. It can be formed on the surface.

  Further, the expander lens 15 is held and driven by two cylindrical lens holders 21 and 22 that are fitted in a slidable state, the electromagnetic coil 31 fixed to the second lens holder 22, and the electromagnetic coil 31. Since the operations are performed by the magnets 32 arranged to face each other, these configurations can be made very compact, and the number of components can be reduced and the assembly can be facilitated.

  In addition, since grease is applied between the first lens holder 21 and the second lens holder 22, the second lens holder 22 slides smoothly when an electric current is passed through the electromagnetic coil 31 to adjust the lens interval. Is easy. Further, when the current is stopped, the grease becomes a resistance and the position of the second lens holder 22 is maintained, so that the optical pickup device can be operated while the current of the electromagnetic coil 31 is stopped after the adjustment of the lens interval. I can do it.

The resistance between the first lens holder 21 and the second lens holder 22 can be adjusted by appropriately designing the viscosity, the depth, the width, and the length of the concave groove 21d that serves as a grease reservoir. The second lens holder 22 can be smoothly slid during the lens interval adjustment, and an optimum resistance can be obtained so that the second lens holder 22 is stopped after the lens interval adjustment.
[Second Embodiment]
FIG. 4 is a cutaway perspective view showing a drive mechanism of the expander lens according to the second embodiment.

  In the second embodiment, the second lens holder 22A that holds the convex lens 15b is fixed, while the first lens holder 21A that holds the concave lens 15a is movable.

However, in this embodiment, the second lens holder 22A is fixed to the base frame of the apparatus, while the first lens holder 21A is in a free state. Further, the electromagnetic coil 31A is fixed to a fixing step 21g provided on the rear end side (traveling wave incident side) of the first lens holder 21A, and the magnet 32A is disposed at a position facing the electromagnetic coil 31A. Yes.
[Third Embodiment]
FIG. 5 is a cutaway perspective view showing the drive mechanism of the expander lens according to the third embodiment.

  The drive mechanism of the expander lens 15 of this embodiment is fixed to the base frame of the apparatus while holding the concave lens 15a on the cylindrical first lens holder 21 as in the embodiment of FIG. The lens holder 21 has a structure in which a cylindrical second lens holder 22B is fitted to the lens holder 21 so that the outer peripheral surface can be slid in the optical axis direction and the convex lens 15b is held by the second lens holder. In addition to such a structure, a coil spring 24 is provided as a biasing means that biases the second lens holder 22B in the direction in which the lens interval is narrowed, and a spring receiver 25 that fixes one end of the coil spring 24 is provided. .

  The second lens holder 22B is provided with a circular groove 22d for accommodating the coil spring 24 on one end side (the traveling wave emission side), and the spring receiver 25 is provided on the base frame of the apparatus.

  According to the drive mechanism of the expander lens 15 having such a configuration, when the electromagnetic coil 31 is not energized, the second lens holder 22B is pushed by the coil spring 24 and one end thereof is the first lens holder 21. It is moved and fixed to a position where it abuts against the flange 21a.

  When the electromagnetic coil 31 is energized, the second lens holder 22B slides in the direction to open the lens interval, and the second driving force generated in the electromagnetic coil 31 is balanced with the force of the coil spring 24. The lens holder 22B stops.

  According to the optical pickup device 1 of this embodiment, since the initial position of the expander lens 15 is fixed, the lens interval adjustment process can be performed with a constant operation every time, and the control thereof is easy. .

  Also, by setting the lens interval in the initial state of the expander lens 15 so as to match the recording surface of the 0th layer of the optical disc, the lens interval necessary for accessing the 0th layer can be easily obtained. In addition, it is not necessary to energize the electromagnetic coil 31 when accessing the 0th layer.

Also, when accessing the 0th layer, if fine adjustment of the lens interval is necessary, or if it is desired to increase the mounting margin or the dimension margin of the lens holder, the initial lens interval is set to By setting the length slightly shorter than the length suitable for the recording surface of the 0th layer, the lens interval is adjusted by moving the second lens holder 22B slightly from the initial position even when accessing the 0th layer. I can do it.
[Fourth Embodiment]
FIG. 6 is a cutaway perspective view showing a drive mechanism of an expander lens according to the fourth embodiment.

  In the drive mechanism of the expander lens 15 of this embodiment, a coil spring 24 as urging means is provided between the first lens holder 21 and the second lens holder 22C, and the second lens holder 22C is provided as the expander lens 15. The lens is biased in the direction of separating the lens intervals.

  In this embodiment, a cylindrical housing groove 22h that houses the coil spring 24 is provided on the traveling wave incident side of the second lens holder 22C, and the coil spring 24 is housed, while the coil spring 24 that protrudes from the housing groove 22h. One end is brought into contact with the flange 21 a of the first lens holder 21.

  Further, the wall surface 51 of the base frame is disposed on one end side (traveling wave emission side) of the second lens holder 22C, and the position where the one end of the second lens holder 22C is in contact with and fixed to the wall surface 51 is the initial position. Is in position.

According to such a configuration, it is possible to set the initial position where the energization of the electromagnetic coil 31 is stopped and the lens interval is widened so as to match the recording surface of the first layer of the optical disc. Therefore, by setting in this way, it is possible to easily obtain the lens interval necessary for recording and reproducing data on the recording surface of the first layer, and at the time of accessing the first layer. It is not necessary to energize the electromagnetic coil 31.
[Fifth Embodiment]
FIG. 7 is a cutaway perspective view showing a drive mechanism of an expander lens according to the fifth embodiment.

  The drive mechanism of the expander lens 15 of this embodiment is such that the second lens holder 22D is urged from two directions, ie, a direction in which the lens interval is widened and a direction in which the distance is narrowed, and the intermediate position is set as the initial position.

  In this embodiment, a cylindrical housing groove 22i for housing the first coil spring 24a on one side of the second lens holder 22D and a cylindrical housing groove 22j for housing the second coil spring 24b on the other side. And a spring receiver 25 for holding the other end of the second coil spring 24b is provided on the base frame at the tip of the second lens holder 22D.

  Then, the first coil spring 24a is accommodated in the accommodation groove 22i and one end protruding from the accommodation groove 22i is brought into contact with the flange 21a of the first lens holder 21, so that the second lens holder 22D is attached in the traveling wave direction. Has come to be.

  Also, the second coil spring 24b is housed in the housing groove 22j on the opposite side and one end protruding from the housing groove 22j is brought into contact with the spring receiver 25, whereby the second lens holder 22D is urged in the direction opposite to the traveling wave. It has come to be.

  Accordingly, when the electromagnetic coil 31 is not energized, the second lens holder 22D is stopped at a position where the urging forces of the two coil springs 24a and 24b are balanced, and the stop position at this time is the lens of the expander lens 15. The biasing forces of the coil springs 24a and 24b are set so that the interval is intermediate between the length corresponding to the 0th layer of the optical disc and the length corresponding to the 1st layer.

  In such a configuration, by passing an electric current through the electromagnetic coil 31, an electromagnetic force is applied to the second lens holder 22D to narrow the lens interval to match the recording surface of the 0th layer of the optical disk, or to pass a reverse current. Thus, the lens interval can be widened to match the recording surface of the first layer of the optical disc.

  According to such a configuration, since the initial position of the second lens holder 22D is constant, the lens position adjustment process can be performed with the same operation every time, and the control thereof is easy.

  In addition, since the initial position is set between the position that matches the 0th layer and the position that matches the 1st layer of the optical disc, the current that flows through the electromagnetic coil 31 when matching the 0th layer and the 1st layer is only the direction. On the contrary, the size is the same. The drive circuit of the electromagnetic coil 31 needs to have predetermined operating characteristics such as response characteristics and stability within a range of output currents that match the lens interval between the zeroth layer and the first layer of the optical disc. Since the output current range that must be satisfied is small, the drive circuit can be designed easily.

  The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the grease accumulation on the guide surface shown in the first embodiment may be eliminated, or the grease itself may not be applied. In addition, the detailed structure specifically shown in the embodiment, such as the shape of the lens holder lens holding portion and the shape of the coil spring or electromagnetic coil holding portion, can be appropriately changed without departing from the spirit of the invention. is there.

  INDUSTRIAL APPLICABILITY The present invention can be used for an optical pickup device that records and reproduces data on an optical disc such as a blue-violet laser optical disc or a DVD (digital versatile disc).

It is a figure which shows the structure of the optical system of the optical pick-up apparatus of embodiment of this invention. It is a perspective view which shows the state which fractured | ruptured the expander lens and its drive mechanism in the center. It is the perspective view which looked at the state which fractured | ruptured in the center the structure which concerns on a movable lens among the mechanisms of FIG. It is a fracture | rupture perspective view which shows the drive mechanism of the expander lens of 2nd Embodiment. It is a fracture | rupture perspective view which shows the drive mechanism of the expander lens of 3rd Embodiment. It is a fracture | rupture perspective view which shows the drive mechanism of the expander lens of 4th Embodiment. It is a fracture | rupture perspective view which shows the drive mechanism of the expander lens of 5th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 15 Expander lens 15a Concave lens 15b Convex lens 21,21A 1st lens holder 22-22D 2nd lens holder 30 Drive apparatus (drive means)
31 Electromagnetic coil 32 Magnet 24, 24a, 24b Coil spring (biasing means)

Claims (8)

In an optical pickup device that records or reproduces data by irradiating an optical disc with laser light,
An expander lens having a first lens and a second lens and capable of correcting the spherical aberration of the laser light by changing the distance between these lenses;
A first lens holder that is formed in a cylindrical shape and has a concave groove that holds the first lens and allows a laser beam to pass through an inner hollow portion and in which a viscous body is accumulated on an outer peripheral surface;
It is formed in a cylindrical shape, holds the second lens, allows laser light to pass through the inner hollow portion, and so that the inner peripheral surface of the cylindrical portion overlaps with the outer peripheral surface of the first lens holder via a viscous body. A second lens holder fitted to the first lens holder;
Driving means comprising an electromagnetic coil fixed to the second lens holder and a magnet for applying a magnetic field to the electromagnetic coil;
The second lens holder is slid in the optical axis direction along the outer peripheral surface of the first lens holder by the driving force of the driving means so that the lens interval between the first lens and the second lens is changed. An optical pickup device configured to be configured. In an optical pickup device that records or reproduces data by irradiating an optical disc with laser light,
An expander lens having a first lens and a second lens and capable of correcting the spherical aberration of the laser light by changing the distance between these lenses;
A first lens holder which is formed in a cylindrical shape and holds the first lens and allows laser light to pass through an inner hollow portion;
The first lens holder is formed in a cylindrical shape, holds the second lens, allows laser light to pass through the inner hollow portion, and covers the inner peripheral surface of the cylindrical portion on the outer peripheral surface of the first lens holder. A second lens holder fitted to
Drive means for exerting a force in the optical axis direction on the first lens holder or the second lens holder by electromagnetic force;
An optical pickup characterized in that the first lens holder or the second lens holder is slid in the optical axis direction by the driving force of the driving means to change the lens interval of the expander lens. apparatus.   3. The optical pickup device according to claim 2, wherein a viscous body is interposed on a joint surface between the first lens holder and the second lens holder.   4. The optical pickup device according to claim 3, wherein a concave groove for accumulating the viscous material is provided on a joint surface between the first lens holder and the second lens holder. The first lens holder is fixed and the second lens holder is movable,
A biasing means for imparting a biasing force to the second lens holder;
5. The optical pickup according to claim 2, wherein the second lens holder is returned to an initial position by the biasing means when the driving means is in an inoperative state. apparatus. The optical pickup device according to claim 5, wherein data is recorded or reproduced with respect to an optical disc having a recording surface of at least two layers.
2. The optical pickup device according to claim 1, wherein an initial position of the second lens holder is set to a position corresponding to one of the recording surfaces of the two layers. The optical pickup device according to claim 5, wherein data is recorded or reproduced with respect to an optical disc having a recording surface of at least two layers.
The optical pickup device, wherein the initial position of the second lens holder includes a position corresponding to the recording surfaces of the two layers in a movable range and is set at a position deviating from the position. The optical pickup device according to claim 5, wherein data is recorded or reproduced with respect to an optical disc having a recording surface of at least two layers.
The biasing means includes a first spring that biases the second lens holder in a first direction along the optical axis direction and a second spring that biases the second lens holder in a direction opposite to the first direction. ,
The position where the forces of the first spring and the second spring balance is the initial position of the second lens holder, and the initial position corresponds to the recording surface of one of the two layers and the other. An optical pickup device, wherein the optical pickup device is set at an intermediate position between positions corresponding to the recording surface of the layer.

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