JP2014006952A - Objective lens driving device and optical pickup device with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens driving device capable of easily adjusting a rotational position around an optical axis of an objective lens installed on a lens holder.SOLUTION: An objective lens driving device 23 comprises: an objective lens 31 including a lens body part 53 and an edge part 54 formed along the outer periphery of the lens body part 53; and a lens holder 32 which has the objective lens 31 placed thereon and has an annular support part 64 supporting the edge part 54 of the objective lens 31 placed on the lens holder, from one side in an optical axis direction. A projecting portion 58 projecting downward is formed on a lower surface part 56 of the edge part 54, and a plurality of fitting parts 66 to which the projecting portion 58 can be fitted is formed along a circumferential direction of the support part 64 of the lens holder 32, and a recessed portion 59 to which a bar-shaped adjustment tool 70 used to rotate the objective lens 31 placed on the lens holder 32 around its optical axis J1 can be inserted is formed in the edge part 54.

Description

  The present invention relates to an objective lens driving device that drives an objective lens and an optical pickup device including the objective lens driving device.

  An objective lens driving device uses a light beam of a predetermined wavelength emitted from a light source such as a semiconductor laser as a disc shape such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and a BD (Blu-ray Disc, registered trademark). An objective lens for focusing as a light spot on an information recording surface of a recording medium (hereinafter sometimes referred to as “optical disk”) is provided, and by moving the objective lens in the focus direction and the tracking direction, This is a device that performs focus control to control the distance between the information recording surface and the objective lens, and performs tracking control to control the objective lens to follow the information track of the optical disc.

  Such an objective lens driving device is mounted on an optical pickup device that records or reproduces information on an optical disc. Here, the focus direction corresponds to the direction in which the optical axis of the light beam guided to the objective lens extends, and the tracking direction corresponds to one radial direction of the optical disk.

  The objective lens driving device mainly includes an objective lens, a lens holder for holding the objective lens, a drive mechanism for moving the lens holder in the focus direction and the tracking direction, and the like on the information recording surface of the optical disc. Opposed.

  An objective lens used in an optical pickup device is generally manufactured by injection molding using an acrylic plastic material such as PMMA (Polymethylmethacrylate). Specifically, molten plastic is injected from a gate into a cavity using a molding die, and this is cooled and solidified. For this reason, optical distortion (astigmatism) is likely to occur in the objective lens due to the influence of the resin flow during molding. Even in the case of objective lenses manufactured using the same cavity, the astigmatism of the objective lens may vary from lot to lot due to variations in molding conditions from lot to lot.

  Therefore, conventionally, when an objective lens is attached to a lens holder, astigmatism of the objective lens and astigmatism of an optical system other than the objective lens in the optical pickup device, such as a collimator lens, are as much as possible. Astigmatism of the entire optical pickup apparatus is reduced by rotating the objective lens around its optical axis so as to cancel each other and adjusting the position of the objective lens to the lens holder.

  For example, in Patent Document 1, in order to facilitate the position adjustment around the optical axis of the objective lens, both the objective lens and the lens holder are provided with clear marks in the rotation direction around the optical axis of the objective lens. Technology is disclosed.

  FIG. 9 is a perspective view showing the configuration of the objective lens 100 and the lens holder 110 according to the related art described in Patent Document 1, and FIG. 10 shows a state in which the objective lens 100 is installed on the lens holder 110. It is sectional drawing when cut | disconnecting by the virtual one plane containing 100 optical axes J. FIG.

  According to the prior art described in Patent Document 1, the objective lens 100 is formed with a convex portion 102 protruding outward in one radial direction perpendicular to the optical axis J, and the objective lens 100 is mounted on the lens holder 110. A convex portion 102 of the objective lens 100 is fitted as a mark of the fitting position of the objective lens 100 to the lens holder 110 at a position facing the outer peripheral portion 101a of the edge portion 101 of the objective lens 100 on the upper surface portion 111 to be placed. A plurality of mating portions 113 are provided. Such a fitting portion 113 is formed in a groove shape by providing a plurality of ribs 112 extending in an arc shape with a gap therebetween in the circumferential direction.

JP 2004-253080 A

  According to the prior art described in FIG. 9 and FIG. 10, the objective lens 100 installed in the lens holder 110 rotates around the optical axis J in a state where the convex portion 102 is fitted to the one fitting portion 113. In order to change the position, the objective lens 100 must be lifted from the lens holder 110 using an instrument such as tweezers so that the convex portion 102 is detached from the fitting portion 113.

  Since the adjustment process of the rotation position of the objective lens 100 is conventionally performed manually, the adjustment process is performed when the operator lifts the objective lens 100 each time using an instrument to change the rotation position. There is a problem that the time required for the process becomes longer. Further, when the objective lens 100 is sandwiched by an instrument such as tweezers, there is a problem that the objective lens 100 is deformed by an external force applied to the objective lens 100 and the optical aberration of the objective lens 100 is deteriorated.

  An object of the present invention is to provide an objective lens driving device capable of easily adjusting the rotational position of the objective lens installed in the lens holder around the optical axis, and an optical pickup device including the objective lens driving device.

The present invention includes an objective lens having a lens body portion having lens surfaces formed on both side surfaces in the optical axis direction, and an edge portion formed along the outer periphery of the lens body portion;
A lens holder on which the objective lens is placed, and a lens having an annular support portion that supports the edge portion of the objective lens from one side in the optical axis direction when the objective lens is placed. An objective lens driving device comprising a holder,
A convex portion projecting to one side in the optical axis direction is formed on a surface portion on one side in the optical axis direction of the edge portion, and the convex portion is formed along the circumferential direction on the support portion of the lens holder. A plurality of fitting parts that can be fitted to the part are formed,
The edge portion is formed with a recess into which a rod-shaped adjustment tool used for rotating the objective lens placed on the lens holder around its optical axis can be inserted. An objective lens driving device.

In the present invention, one convex portion is formed,
The recess is formed at a position close to the convex portion in a circumferential direction around the optical axis.

In the present invention, one convex portion is formed,
The recess is formed at a position farthest from the convex portion in a circumferential direction around the optical axis.

Further, the present invention provides an objective lens having a lens main body portion having lens surfaces formed on both side surfaces in the optical axis direction, and an edge portion formed along the outer periphery of the lens main body portion,
A lens holder on which the objective lens is placed, and a lens having an annular support portion that supports the edge portion of the objective lens from one side in the optical axis direction when the objective lens is placed. An objective lens driving device comprising a holder,
A convex portion is formed on the support portion of the lens holder, and the convex portion can be fitted to a surface portion on one side of the edge portion in the optical axis direction along the circumferential direction around the optical axis. Multiple joints are formed,
The edge portion is formed with a recess into which a rod-shaped adjustment tool used for rotating the objective lens placed on the lens holder around its optical axis can be inserted. An objective lens driving device.

  In the invention, it is preferable that the recess is a groove formed in the outer peripheral portion of the edge portion so as to extend in the optical axis direction.

  In the invention, it is preferable that the recess is a hole formed so as to extend in the optical axis direction from a surface portion on the other side in the optical axis direction in the edge portion.

  Further, the invention is characterized in that the convex portion is formed in a hemispherical shape or a conical shape, and the fitting portion is formed in a mortar shape.

  Further, the invention is characterized in that eight fitting portions are formed at equal intervals along the circumferential direction.

  The present invention is also an optical pickup device comprising the objective lens driving device.

  According to the present invention, the convex portion is formed on the surface portion of the edge portion of the objective lens that faces the support portion of the lens holder, and the convex portion formed on the objective lens can be fitted to the support portion of the lens holder. A plurality of fitting portions are formed, and a concave portion in which a rod-shaped adjustment tool used for rotating the objective lens placed on the lens holder around its optical axis can be inserted into the edge portion of the objective lens. A place is formed.

  Therefore, the objective lens is rotated in the circumferential direction by inserting an adjustment tool into the recess of the edge portion and applying a rotational force to the objective lens in the circumferential direction around the optical axis through the adjustment tool. Thus, the state in which the convex portion is fitted to the one fitting portion can be shifted to the state in which the convex portion is fitted to the fitting portion adjacent to the one fitting portion.

  That is, by rotating the objective lens without lifting the objective lens, it is possible to sequentially position the objective lens at a plurality of rotational positions defined by the fitting portion, and astigmatism depends on the rotational position of the objective lens. It is possible to reduce the work time required for the adjustment process for adjusting the objective lens and to avoid the deterioration of the optical aberration of the objective lens caused by the instrument for lifting the objective lens.

It is a figure showing simplified composition of optical pick-up device 1 concerning one embodiment of the present invention. It is a top view which shows the objective lens drive device 23 which concerns on one Embodiment of this invention. It is sectional drawing seen from the cut surface line III-III in FIG. FIG. 4 is a diagram illustrating a configuration of an objective lens 31 in a lens unit 33 according to an embodiment of the present invention, FIG. 4A is a plan view of the objective lens 31, and FIG. It is sectional drawing seen from the cut surface line BB in FIG. FIGS. 5A and 5B are diagrams showing a configuration of a lens holder 32 in a lens unit 33 according to an embodiment of the present invention, FIG. 5A is a plan view of the lens holder 32, and FIG. It is sectional drawing seen from the cut surface line BB in FIG. It is a figure for demonstrating the position adjustment process in the lens unit 33 which concerns on this embodiment. It is a figure which shows the structure of 31 A of objective lenses which concern on other embodiment of this invention, Fig.7 (a) is a top view of 31 A of objective lenses, FIG.7 (b) is the cutting | disconnection in Fig.7 (a) It is sectional drawing seen from the surface line BB. FIG. 8A is a diagram for explaining a position adjustment process in the lens unit 33 according to the present embodiment, and FIG. 8A shows a case where the adjustment tool 70 is inserted into the groove 59A from the side of the objective lens 31, and FIG. (B) shows a case where the adjustment tool 70 is inserted into the groove 59 </ b> A from above the objective lens 31. It is a perspective view which shows the structure of the objective lens 100 and the lens holder 110 which concern on a prior art. FIG. 3 is a cross-sectional view of the state in which the objective lens 100 is installed on the lens holder 110 taken along a virtual plane including the optical axis J of the objective lens 100.

  FIG. 1 is a diagram showing a simplified configuration of an optical pickup device 1 according to an embodiment of the present invention. The optical pickup device 1 according to the present embodiment irradiates light from one side of the optical disc 2 to record information on the information recording surface 3 of the optical disc 2 or to record information recorded on the information recording surface 3 of the optical disc 2. Used for playback. Examples of the optical disc 2 include disc-shaped recording media such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and a BD (Blu-ray Disc).

  The optical pickup device 1 collects light emitted from the light source 11, the light emitted from the light source 11 on the information recording surface 3 of the optical disc 2, and the light reflected by the information recording surface 3 of the optical disc 2. Based on the optical system 12, the light receiving means 13 for receiving the reflected light from the information recording surface 3 of the optical disc 2 through the optical system 12, and the light reception result by the light receiving means 13, the light collection by the optical system 12. And a control means 14 for adjusting the light position. Such an optical pickup device 1 is arranged such that the reference optical axis L of the optical system 12 is orthogonal to the optical disc 2 rotated by a spindle motor.

  The light source 11 is realized by a laser diode. The light source 11 emits light in a wavelength range suitable for recording / reproducing of the optical disc 2. For example, when the optical disk 2 is a DVD, a laser diode that emits light in a wavelength region near 650 nm suitable for DVD recording / reproduction is used as the light source 11.

  The optical system 12 diffracts the light emitted from the light source 11 and separates it into a main light beam M and a pair of sub-light beams S1 and S2, and the light beams M, S1 and S2 from the diffraction grating 21 in parallel. An objective lens driving device 23 including a collimator lens 22 for converting light, an objective lens 31 for condensing the light beams M, S1, and S2 from the collimator lens 22 on the information recording surface 3 of the optical disc 2; A light splitter 24 that splits the reflected light of the light beams M, S1, and S2 from the surface 3;

  Irregularities are periodically formed in the diffraction grating 21. The main light beam M is zero-order diffracted light by the diffraction grating 21. Each of the sub-beams S1 and S2 is ± first-order diffracted light by the diffraction grating 21. The sub-beams S1 and S2 are shifted to both sides of the tracking direction T1 and to both sides of the tangential direction T2 with respect to the main beam M on the information recording surface 3 of the optical disc 2. The tracking direction T1 and the tangential direction T2 are orthogonal to the reference optical axis L and orthogonal to each other. The tracking direction T1 corresponds to the radial direction of the optical disc 2. The tangential direction T2 corresponds to the tangential direction of the optical disc 2.

  The objective lens driving device 23 drives the objective lens 31 to be displaced in the focusing direction F and the tracking direction T1 within a movable range including the neutral position. In the neutral position, the optical axis of the objective lens 31 is coaxial with the reference optical axis L. The focusing direction F is a direction along the reference optical axis L and is a direction approaching and separating from the optical disc 2.

  The light splitter 24 is interposed between the diffraction grating 21 and the collimator lens 22. The light splitter 24 transmits the light emitted from the light source 11 without diffracting it, and transmits and diffracts the reflected light from the information recording surface 3 of the optical disk 2.

  The control unit 14 controls the objective lens driving device 23 based on the light reception result by the light receiving unit 13. Specifically, the control unit 14 generates a tracking error signal and a focusing error signal based on the light reception result by the light receiving unit 13, and performs track servo control and focus servo control based on these signals. Accordingly, the objective lens 31 can be driven to be displaced in the focusing direction F and the tracking direction T1 by the objective lens driving device 23 so that the focusing position by the objective lens 31 follows the track of the information recording surface 3.

  FIG. 2 is a plan view showing the objective lens driving device 23 according to one embodiment of the present invention, and FIG. 3 is a cross-sectional view taken along section line III-III in FIG. In FIG. 3, the optical disc 2 is indicated by a virtual line.

  The objective lens driving device 23 includes an objective lens 31 and a lens unit 33 constituted by a lens holder 32 for holding the objective lens 31, and a drive mechanism for driving the lens unit 33 to be displaced in the focusing direction F and the tracking direction T1. 34 and a housing 35 on which the lens unit 33 and the drive mechanism 34 are mounted, and is provided to face the information recording surface 3 of the optical disc 2 as shown in FIG.

  The housing 35 is erected vertically from the base plate 36, a support base support plate 37 that erects vertically from one end of the base plate 36 in the tangential direction T2, and the other end of the base plate 36 in tangential direction T2. It is fixed to the magnet support plate 38.

  The drive mechanism 34 is used to support the lens unit 33, and a plurality of (four in this embodiment) support wires 41 whose one end is connected to the lens holder 32, and the other end of each support wire 41 is A fixed wire support base 42, a focus coil 43, a tracking coil 44, and a magnet 45 are included.

  Each support wire 41 has flexibility and elasticity, and is provided so as to extend along the tangential direction T2. One end portion is fixed to the outer peripheral surface portion of the lens holder 32, and the other end portion is provided. The wire support 42 is fixed.

  The wire support base 42 is fixed to the support base support plate 37. Similarly, the magnet 45 is fixed to the magnet support plate 38. The base plate 36 is formed with a through hole 36a through which the light beams M, S1, S2 from the diffraction grating 21 pass.

  In the objective lens driving device 23, the focus coil 43 provided in the lens holder 32, the magnet support plate 38, and the magnet 45c supported by the magnet support plate 38 form a focus direction magnetic circuit. When the current flows through the lens unit 33, the lens unit 33 is driven in the focusing direction F.

  In the objective lens driving device 23, the tracking coil 44 provided on the lens holder 32, the magnet support plate 38, and the magnet 45 supported on the magnet support plate 38 form a tracking direction magnetic circuit, and the tracking coil. When a current is passed through 44, the lens unit 33 is driven in the tracking direction T1.

  The objective lens driving device 23 drives the lens unit 33 in the focusing direction F and the tracking direction T1 while maintaining the posture of the lens unit 33. Thereby, focus servo control for controlling the distance between the information recording surface 3 of the optical disc 2 and the objective lens 31 is performed, and track servo control for controlling the objective lens 31 to follow the information track of the optical disc 2 is performed.

  FIG. 4 is a diagram illustrating a configuration of the objective lens 31 in the lens unit 33 according to the embodiment of the present invention, FIG. 4A is a plan view of the objective lens 31, and FIG. It is sectional drawing seen from the cut surface line BB in Fig.4 (a).

  The objective lens 31 includes a lens main body 53 that functions as a lens for condensing the light beams M, S1, and S2 from the diffraction grating 21, and outward in the radial direction perpendicular to the optical axis J1 from the lens main body 53. It comprises an annular edge portion 54 formed along the outer periphery of the lens body 53 so as to protrude. That is, the edge portion 54 is a portion provided outside the effective diameter in the objective lens 31. The objective lens 31 is integrally formed of, for example, an acrylic plastic material such as PMMA or glass.

  The lens body 53 is formed with two curved lens surfaces 51 and 52 that are convex outward from each other on both side surfaces in the direction in which the optical axis J1 extends (hereinafter referred to as “optical axis direction”). . Of the two lens surfaces 51 and 52, the lens surface facing the optical disc 2 is the first lens surface 51 in a state where the objective lens 31 is placed on the lens holder 32, and each light beam M, The lens surface on which S1 and S2 are incident is referred to as a second lens surface 52. Hereinafter, when the objective lens 31 is described, in the optical axis direction, the side on which the first lens surface 51 is formed is defined as the upper side, and the opposite side is defined as the lower side.

  The edge portion 54 is connected to the first lens surface 51, is connected to the upper surface portion 55 having an annular edge portion upper surface parallel to a virtual plane perpendicular to the optical axis J1, and the second lens surface 52, and is connected to the optical axis J1. It has a lower surface portion 56 having an annular edge lower surface parallel to a vertical virtual plane, and an outer peripheral portion 57 having a right cylindrical outer peripheral surface coaxial with the optical axis J1.

  In the objective lens 31 according to the present embodiment, one convex portion 58 protruding downward is formed on the lower surface portion 56 of the edge portion 54, and the objective lens 31 placed on the lens holder 32 is provided with its optical axis. A recess 59 is formed into which a rod-shaped adjustment tool 70 (see FIG. 6) used for rotating around J1 can be inserted.

  The convex part 58 is formed in a hemispherical shape in the present embodiment. The shape of the convex portion 58 may be conical in other embodiments. Further, in this embodiment, the recess 59 is realized by a right cylindrical hole drilled so as to extend from the upper surface portion 55 in the optical axis direction. Hereinafter, description will be made assuming that the recess 59 is the hole 59. In this embodiment, the hole 59 is formed so as not to penetrate the edge portion 54, but in other embodiments, the hole 59 may be formed so as to penetrate the edge portion 54.

  In the present embodiment, the hole 59 is formed at a position farthest from the convex portion 58 in the circumferential direction around the optical axis J1. In other words, the hole 59 is formed at a position 180 degrees around the optical axis J1 from the position where the convex portion 58 is formed.

  In this embodiment, the hole 59 is thus formed at the position farthest from the convex portion 58. However, in other embodiments, the hole 59 is formed at a position close to the convex portion 58, for example, above the convex portion 58. May be. In this case, the hole 59 is preferably formed so as not to penetrate the edge portion 54.

  FIG. 5 is a diagram illustrating a configuration of the lens holder 32 in the lens unit 33 according to an embodiment of the present invention, FIG. 5A is a plan view of the lens holder 32, and FIG. It is sectional drawing seen from the cut surface line BB in FIG.5 (b).

  The lens holder 32 is formed of an engineering plastic having insulating properties and high strength and low specific gravity, and is formed of, for example, a PPS (Polyphenylenesulfide) resin and an LCP (Liquid Crystal Polymer) resin.

  The lens holder 32 has a substantially rectangular parallelepiped shape. A right cylindrical hole 61 through which the light beams M, S1, and S2 from the diffraction grating 21 can pass is formed in the thickness direction. It is supported by the four support wires 41 in such a posture that the direction in which the central axis J2 extends and the focusing direction F coincide.

  In the lens holder 32, the inner diameter of the inner peripheral surface portion 62 that defines the hole 61 is determined based on the dimensions of the objective lens 31. Specifically, the inner diameter of the inner peripheral surface portion 62 is larger than the outer diameter of the lens body 53 in the objective lens 31, and the optical axis J1 of the objective lens 31 and the central axis J2 in the lens holder 32 are made to coincide. In such a state, when the objective lens 31 is placed on the upper surface portion 63 that is one surface portion in the thickness direction of the lens holder 32, the dimension can sufficiently support the lower surface portion 56 of the edge portion 54 of the objective lens 31. To be determined. In the present embodiment, that the lower surface portion 56 of the edge portion 54 of the objective lens 31 is sufficiently supported means that at least the inner portion in the radial direction of the lower surface portion 56 of the edge portion 54 is in the radial direction from the convex portion 58. The support is shown in contact with the upper surface portion 63 of the holder 32.

  When the objective lens 31 is placed on the upper surface portion 63 of the lens holder 32 in a state where the optical axis J1 of the objective lens 31 and the central axis J2 of the lens holder 32 are aligned with each other, An annular support portion 64 that supports the lower surface portion 56 is provided.

  Furthermore, the upper surface portion 63 is formed with two wall portions 65 that extend along the outer periphery of the support portion 64 and are erected vertically from the upper surface portion 63 and are arc-shaped in plan view. The inner diameters of the inner peripheral surfaces of the two wall portions 65 are determined to be slightly larger than the outer diameter of the outer peripheral portion 57 of the edge portion 54 of the objective lens 31.

  Therefore, when the objective lens 31 is placed on the upper surface portion 63 of the lens holder 32, the objective lens 31 is fitted between the two wall portions 65, and is perpendicular to the central axis J2 by the two wall portions 65. Positioning in any direction.

  In the lens holder 32 according to the present embodiment, a fitting portion 66 in which a convex portion 58 formed on the edge portion 54 of the objective lens 31 can be fitted to an annular support portion 64 along the circumferential direction thereof. A plurality are formed. Each fitting portion 66 is formed such that the distance from the center axis of the lens holder 32 matches the radial distance from the optical axis J1 to the convex portion 58 in the objective lens 31.

  In the present embodiment, the fitting portion 66 is formed in a shape that penetrates a cone, that is, in a mortar shape, and the convex portion 58 contacts the inner surface of the fitting portion 66 in a state where the convex portion 58 is fitted. It is formed in such a size.

  In the present embodiment, in the present embodiment, in consideration of a reduction in work time and productivity in the position adjustment process described later, the fitting portions 66 are equally spaced along the circumferential direction of the support portion 64 as shown in FIG. One is formed. However, the number of fitting portions 66 is not limited to eight, but may be eight or more, or may be fewer than eight.

  Hereinafter, in the optical pickup device 1 according to the present embodiment, when the objective lens 31 is attached to the lens holder 32, astigmatism of the objective lens 31 and other optical systems other than the objective lens 31 in the optical pickup device 1 (for example, A step of adjusting the position by rotating the objective lens 31 around its optical axis J1 (hereinafter referred to as a “position adjusting step”) so that astigmatism of the collimator lens 22 and the like cancel each other as much as possible. explain.

  FIG. 6 is a diagram for explaining a position adjustment process in the lens unit 33 according to the present embodiment. In FIG. 6, the lens holder 32 is omitted in the lens unit 33 in a state where the objective lens 31 is placed on the lens holder 32.

  In the position adjustment process, first, the objective lens 31 is fitted to any one of the fitting portions 66 formed on the support portion 64 of the lens holder 32 so that the convex portion 58 is fitted to the upper surface portion 63 of the lens holder 32. Placed on. Astigmatism is measured by a measuring device (not shown).

  When astigmatism is measured when the convex portion 58 is fitted to the first fitting portion 66, the objective lens 31 placed on the lens holder 32 is used to rotate around the optical axis J1. The rod-shaped adjustment tool 70 is inserted into the hole 59 from above the objective lens 31 and gives a rotational force to the objective lens 31 in the circumferential direction around the optical axis J via the adjustment tool 70. The objective lens 31 is rotated about the optical axis J1, and the second fitting adjacent to the first fitting portion 66 is started from the state where the convex portion 58 is fitted to the first fitting portion 66. The state is shifted to a state in which the convex portion 58 is fitted to the portion 66. Then, astigmatism is measured again by a measuring device (not shown).

  By repeating the above procedure, astigmatism is measured in a state where the convex portions 58 are fitted to the eight fitting portions 66, respectively, and among these eight measurement results, the measurement result with the smallest astigmatism is obtained. Is obtained. And the position adjustment process is complete | finished by rotating the objective lens 31 using the adjustment tool 70 so that the convex part 58 may fit in the calculated | required fitting part 66. FIG.

  As described above, according to the present embodiment, by rotating the objective lens 31 without lifting the objective lens 31, the objective lens 31 is sequentially positioned at a plurality of rotational positions defined by the fitting portion 66. Therefore, the work time required for the adjustment process for adjusting astigmatism according to the rotational position of the objective lens 31 can be reduced. Moreover, since it is not necessary to lift the objective lens 31 using an instrument, it is possible to avoid the deterioration of the optical aberration of the objective lens 31 due to the use of the instrument.

  Further, according to the present embodiment, the convex portion 58 in the objective lens 31 is formed in a hemispherical shape or a conical shape, and the fitting portion 66 in the lens holder 32 is formed in a mortar shape. Thereby, when a rotational force is applied to the objective lens 31 in the circumferential direction around the optical axis J through the adjustment tool 70 from the state in which the convex portion 58 is fitted to the fitting portion 66, The convex portion 58 can be easily detached from the fitting portion 66. Therefore, the objective lens 31 can be easily rotated with respect to the lens holder 32.

  Further, according to the present embodiment, since the recess is realized by the cylindrical hole 59, the position of the hole 59 is detected, the adjustment tool 70 is inserted into the hole 59, and the optical axis J1 is rotated. A series of operations of rotating by a predetermined angle can be automated by the apparatus.

  In the above embodiment, one convex portion 58 is formed on the edge portion 54 of the objective lens 31. However, in another embodiment, a plurality of convex portions 58 may be formed. However, if the number of the convex portions 58 increases, it becomes difficult to rotate the objective lens 31 around the optical axis J. Therefore, the number of the convex portions 58 is preferably one.

  In the above embodiment, the astigmatism is measured by sequentially fitting the convex portions 58 to each of the plurality of fitting portions 66 formed on the support portion 64 of the lens holder 32, and astigmatism is minimized. However, the present invention is not limited to this, and in the optical pickup device 1 before the objective lens 31 is placed, the astigmatism is reduced in the circumferential direction by a measuring device (not shown). The position is adjusted by installing the objective lens 31 in the lens holder 32 so that a predetermined circumferential position of the objective lens 31 coincides with the obtained position. Also good.

  In this case, the position adjustment using the adjustment tool 70 is such that the convex portion 58 formed on the edge portion 54 of the objective lens 31 is fitted into a fitting portion 66 different from the fitting portion 66 determined in advance in the lens holder 32. In this state, when the objective lens 31 is placed on the lens holder 32, the objective lens 31 is rotated around the optical axis J so that the convex portion 58 is fitted in the predetermined fitting portion 66. Is called.

  FIG. 7 is a diagram showing a configuration of an objective lens 31A according to another embodiment of the present invention, FIG. 7A is a plan view of the objective lens 31A, and FIG. 7B is a plan view of FIG. It is sectional drawing seen from the cut surface line BB in a). Since the objective lens 31A according to the present embodiment is configured in the same manner as the objective lens 31 according to the above-described embodiment except for the recess 59A, the same configuration is denoted by the same reference numeral, and redundant description is given. Omitted.

  In the objective lens 31A according to the present embodiment, one convex portion 58 protruding downward is formed on the lower surface portion 56 of the edge portion 54, and the objective lens 31A placed on the lens holder 32 is provided with its optical axis. A recess 59A into which a rod-shaped adjustment tool 70 (see FIG. 6) used for rotating around J1 can be inserted.

  In the present embodiment, the recess 59A is realized by a rectangular groove formed in the outer peripheral portion 57 of the edge portion 54 so as to extend in the optical axis direction. Hereinafter, description will be made assuming that the recess 59A is the groove 59A.

  FIG. 8 is a diagram for explaining a position adjustment process in the lens unit 33 according to the present embodiment. In FIG. 8, the lens holder 32 is omitted from the lens unit 33 in a state where the objective lens 31 </ b> A is placed on the lens holder 32.

  In the present embodiment, when astigmatism is measured when the convex portion 58 is fitted to the first fitting portion 66, the objective lens 31A placed on the lens holder 32 is moved around its optical axis J1. A rod-shaped adjustment tool 70 used for rotation is inserted into the groove 59A from the side or the upper side of the objective lens 31A, and the circumference around the optical axis J with respect to the objective lens 31A via the adjustment tool 70. By applying a rotational force in the direction, the objective lens 31A is rotated around the optical axis J1, and the first fitting portion 66 is engaged with the first fitting portion 66 from the state in which the convex portion 58 is fitted. The second fitting part 66 adjacent to the second fitting part 66 is shifted to a state where the convex part 58 is fitted.

  8A shows the case where the adjustment tool 70 is inserted into the groove 59A from the side of the objective lens 31A, and FIG. 8B shows the adjustment tool 70 inserted into the groove 59A from above the objective lens 31A. This shows the case where

  Thus, even if the recess formed in the edge portion of the objective lens is not the hole but the groove 59A, the fitting portion 66 can rotate the objective lens 31A without lifting the objective lens 31A. Since the objective lens 31A can be sequentially positioned at a plurality of prescribed rotational positions, it is possible to reduce the work time required for the adjustment process for adjusting astigmatism according to the rotational position of the objective lens 31A. Further, since it is not necessary to lift the objective lens 31A using an instrument, it is possible to avoid the deterioration of the optical aberration of the objective lens 31A due to the use of the instrument.

  In this embodiment, when the adjustment tool 70 is inserted into the groove 59A from the side of the objective lens 31A, the height of the wall portion 65 provided on the upper surface portion 63 of the lens holder 32 is set to the edge of the objective lens 31A. It is preferable that the thickness of the portion 54 be sufficiently small.

  In the above embodiment, one convex portion 58 is formed on the edge portion 54 of the objective lens 31, 31A, and eight fitting portions 66 are formed on the support portion 64 of the lens holder 32. However, other embodiments are described. Then, eight fitting portions 66 may be formed on the edge portion 54 of the objective lenses 31 and 31 </ b> A, and one convex portion 58 may be formed on the support portion 64 of the lens holder 32. Also in this embodiment, there exists an effect similar to the above.

DESCRIPTION OF SYMBOLS 1 Optical pick-up apparatus 23 Objective lens drive device 31 Objective lens 32 Lens holder 53 Lens main-body part 54 Edge part 56 Lower surface part 58 Convex part 59 Concave part 64 Support part 65 Wall part 66 Fitting part

Claims (9)

An objective lens having a lens body formed with lens surfaces on both side surfaces in the optical axis direction, and an edge formed along the outer periphery of the lens body;
A lens holder on which the objective lens is placed, and a lens having an annular support portion that supports the edge portion of the objective lens from one side in the optical axis direction when the objective lens is placed. An objective lens driving device comprising a holder,
A convex portion projecting to one side in the optical axis direction is formed on a surface portion on one side in the optical axis direction of the edge portion, and the convex portion is formed along the circumferential direction on the support portion of the lens holder. A plurality of fitting parts that can be fitted to the part are formed,
The edge portion is formed with a recess into which a rod-shaped adjustment tool used for rotating the objective lens placed on the lens holder around its optical axis can be inserted. Objective lens drive. One convex part is formed,
The objective lens driving device according to claim 1, wherein the recess is formed at a position close to the convex portion in a circumferential direction around the optical axis. One convex part is formed,
2. The objective lens driving device according to claim 1, wherein the recess is formed at a position farthest from the convex portion in a circumferential direction around the optical axis. An objective lens having a lens body formed with lens surfaces on both side surfaces in the optical axis direction, and an edge formed along the outer periphery of the lens body;
A lens holder on which the objective lens is placed, and a lens having an annular support portion that supports the edge portion of the objective lens from one side in the optical axis direction when the objective lens is placed. An objective lens driving device comprising a holder,
A convex portion is formed on the support portion of the lens holder, and the convex portion can be fitted to a surface portion on one side of the edge portion in the optical axis direction along the circumferential direction around the optical axis. Multiple joints are formed,
The edge portion is formed with a recess into which a rod-shaped adjustment tool used for rotating the objective lens placed on the lens holder around its optical axis can be inserted. Objective lens drive.   5. The objective lens driving device according to claim 1, wherein the recess is a groove formed in an outer peripheral portion of the edge portion so as to extend in the optical axis direction. 6.   The said recess is a hole drilled so as to extend in the optical axis direction from a surface portion on the other side in the optical axis direction in the edge portion. The objective lens drive device described in 1.   The objective lens driving device according to claim 1, wherein the convex portion is formed in a hemispherical shape or a conical shape, and the fitting portion is formed in a mortar shape.   8. The objective lens driving device according to claim 1, wherein eight fitting portions are formed at equal intervals along the circumferential direction. 9.   An optical pickup device comprising the objective lens driving device according to claim 1.

Images