JP2008152874A - Optical element for optical pickup device and optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element for an optical pickup device, capable of using different kinds of optical disks and accurately performing lens driving, and to provide the optical pickup device. <P>SOLUTION: A padding part (weight) FL1 as a balance-adjusting means is formed at an end part on a second objective lens OL2 side of a flange part FL of the optical element OE. The center of gravity Go of the optical element OE can be formed close to the center of the optical element itself, by forming such a padding part FL1 on the side of the second objective lens OL2 that has a thin axial thickness and a small volume. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element for an optical pickup device and an optical pickup device capable of recording and / or reproducing information on different types of optical information recording media (also referred to as optical discs).

  Research and development of high-density optical disc systems that can record and / or reproduce information (hereinafter, “recording and / or reproduction” is referred to as “recording / reproduction”) using a blue-violet semiconductor laser having a wavelength of about 400 nm in recent years. Development is progressing rapidly. As an example, in an optical disc for recording / reproducing information with specifications of NA 0.85 and light source wavelength 405 nm, so-called Blu-ray Disc (hereinafter referred to as BD), DVD (NA 0.6, light source wavelength 650 nm, storage capacity 4, 7 GB) Can record information of 23 to 27 GB per layer on an optical disk with a diameter of 12 cm, which is the same size as the above, and an optical disk that records and reproduces information with specifications of NA 0.65 and light source wavelength 405 nm, so-called With HD DVD (hereinafter referred to as HD), information of 15 to 20 GB per layer can be recorded on an optical disk having a diameter of 12 cm. In the BD, since coma aberration generated due to the tilt (skew) of the optical disk increases, the protective layer is designed to be thinner than in the DVD (0.1 mm with respect to 0.6 mm of the DVD) The amount of coma due to skew is reduced. Hereinafter, such an optical disc is referred to as a “high density optical disc” in the present specification.

  Also, given the reality that DVDs and CDs (compact discs) on which a wide variety of information is recorded are currently being sold, information can be appropriately recorded on as many different types of optical discs as possible with a single player. It is desired to enable reproduction. Furthermore, considering that the optical pickup device is mounted on a notebook personal computer or the like, it is not only necessary to have compatibility with a plurality of types of optical discs, but it is important to further promote downsizing.

  Here, in the optical pickup device, it is preferable to realize compactness if it is possible to use different optical disks interchangeably using a single objective lens. However, considering the specifications of the high-density optical disk, it can be said that it is technically difficult to share the objective lens. For example, BD and HD use light beams having the same wavelength even though the protective substrate thickness is different, so that aberration correction cannot be performed using a diffractive structure, and it is difficult to share an objective lens. There is.

In this way, in a compatible optical pickup device, in order to achieve both “common” and “compact” objective lenses and to obtain more favorable optical performance, a composite optical element in which lenses are arranged in parallel and integrally molded is used. It is possible to use it. Such a composite optical element has a merit that the interval between the lenses can be narrowed since the flange portion can be made common as compared with the case where two lenses molded individually are used. There is also an advantage that assembly adjustment can be simplified and cost can be reduced. An example of such a composite optical element is described in Patent Document 1.
JP-A-9-115170

  By the way, compared with an objective lens for CD, an objective lens for a high-density optical disc generally has a high NA and a deep optical surface. Specifically, as the NA increases, the axial thickness of the objective lens increases, and its optical surface approaches a spherical shape from a planar shape. Therefore, if the volume of the other objective lens part is greatly different from the one objective lens part, the center of gravity of the composite optical element is often not centered. When such a composite optical element is assembled to a bobbin and tracking or focusing operation is performed, a phenomenon such as twisting occurs around the actual center of gravity, and unintended lens tilt, unnecessary vibration of the bobbin, resonance, etc. are caused. There is a fear.

  The present invention has been made in view of the problems of the prior art, and can be used for an optical pickup device that can use different types of optical disks, prevent unnecessary vibration such as bobbin resonance, and perform lens driving with high accuracy. It is an object of the present invention to provide an optical element and an optical pickup device.

  In this specification, an optical disk (also referred to as an optical information recording medium) that uses a blue-violet semiconductor laser or a blue-violet SHG laser as a light source for recording / reproducing information is generally referred to as a “high-density optical disk”, and NA0 In addition to a standard optical disc (for example, BD: Blu-ray Disc) in which information is recorded / reproduced by an objective optical system of .85 and the thickness of the protective layer is about 0.1 mm, NA 0.65 to 0.67 Information is recorded / reproduced by the objective optical system, and includes a standard optical disc (for example, HD DVD: also simply referred to as HD) having a protective layer thickness of about 0.6 mm. In addition to an optical disc having such a protective layer on its information recording surface, an optical disc having a protective film with a thickness of several to several tens of nanometers on the information recording surface, the thickness of the protective layer or protective film It also includes an optical disc with 0. In this specification, the high-density optical disk includes a magneto-optical disk that uses a blue-violet semiconductor laser or a blue-violet SHG laser as a light source for recording / reproducing information.

  Furthermore, in this specification, DVD is a generic term for DVD series optical disks such as DVD-ROM, DVD-Video, DVD-Audio, DVD-RAM, DVD-R, DVD-RW, DVD + R, DVD + RW, and the like. Is a general term for CD-series optical disks such as CD-ROM, CD-Audio, CD-Video, CD-R, CD-RW and the like. The recording density is highest in the high-density optical disc, and then decreases in the order of DVD and CD.

The optical element for an optical pickup device according to claim 1 is an optical element in which a single objective lens part and a plurality of light source parts and a first objective lens part and a second objective lens part having different axial thicknesses are integrally formed. And condensing the light beam from the light source on the information recording surface of the first optical information recording medium via the first objective lens unit, thereby recording information on the information recording surface. The information can be recorded and / or recorded on the information recording surface by focusing on the information recording surface of the second optical information recording medium via the second objective lens unit. Or an optical element for an optical pickup device that can be reproduced,
The optical element has a balance adjusting means.

  Here, “the optical element in which the first objective lens unit and the second objective lens unit are integrally formed” means that the first objective lens unit and the second objective lens unit are fused (for example, The optical element having the first objective lens part and the second objective lens part is obtained not only by injection molding), but also the optical element having the first objective lens part and the second objective lens part. The optical element is formed separately, and includes an optical element that is integrated by bonding or fitting later.

  The principle of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a comparative example showing a tracking-driven bobbin BB, and FIG. 2 is a perspective view of a comparative example showing a tilt-driven bobbin BB. Coils CL are arranged on both sides of a bobbin BB supported by two wires W with respect to a frame (not shown), and a magnet (not shown) is provided on the surface of the bobbin BB facing the coil CL. The bobbin BB is tracking driven (see FIG. 1), focusing driving, tilt driving (FIG. 2) against the elastic force of the wire W using the magnetic field generated by applying current to the coils CL. See).

  FIGS. 3 and 4 are further perspective views similar to FIGS. 1 and 2 according to the comparative example. FIG. 3 shows a state before the optical element OE is assembled, and FIG. 4 shows a state after the assembly. The optical element OE formed integrally with the first objective lens portion OL1 and the second objective lens portion OL2 is assembled and bonded to the rectangular opening RAP of the bobbin BB, and is driven by the coil CL. Yes.

  Here, since the bobbin BB shown in FIGS. 3 and 4 has a rectangular plate shape having a rectangular opening RAP at the center, the center of gravity Gb is located at the center when viewed from the top, front, and side surfaces. On the other hand, the first objective lens section OL1 has a higher NA than the second objective lens section OL2, and thus has a large axial thickness and a deep optical surface. Accordingly, the center of gravity position Go of the optical element OE is closer to the first objective lens section OL1.

  FIG. 5A is a diagram showing the position of the center of gravity Go when the optical element OE is viewed from the front, and FIG. 5B is the position of the center of gravity Go when the optical element OE is viewed from the side. FIG. 5C is a diagram showing the position of the center of gravity Gb when the bobbin BB is viewed from the front, and FIG. 5D is the position of the center of gravity Gb when the bobbin BB is viewed from the side. FIG.

  Here, when the optical element OE is mounted on the bobbin BB, the position of the total center of gravity Gt of the optical element OE and the bobbin BB is shifted from the position of the center of gravity Gb of the bobbin BB. Then, in FIG. 4, there is a difference between the distance AGt (2) from the attachment position of the left wire W to the total gravity center Gt and the distance AGt (1) from the attachment position of the right wire W to the total gravity center Gt (AGt Since (2)> AGt (1)), there is a possibility that the bobbin BB is driven to be twisted when an equal magnetic force is applied from the coils CL on both sides.

  On the other hand, according to the present invention, as shown in FIG. 6, the optical element OE has a built-up portion (weight) as a balance adjusting means at the end portion on the second objective lens portion OL2 side in the flange portion FL. FL1 is formed. By forming such a built-up portion FL1 on the second objective lens portion OL2 side having a small axial thickness and a small volume, the center of gravity Go of the optical element OE is positioned within the center range of the optical element OE. Can do. More specifically, in FIG. 6, the distance AGo (2) from the attachment position of the left wire W to the center of gravity Go is equal to the distance AGo (1) from the attachment position of the right wire W to the center of gravity Go (AGo). It is preferable that (1) = AGo (2) = A) or a slight difference (within the center range of the optical element OE). In this case, if the rectangular opening RAP of the bobbin BB is located at the center thereof, the total center of gravity Gt of the optical element OE and the bobbin BB is in the vicinity of the bobbin BB with the optical element OE mounted on the bobbin BB. Will exist.

  Here, the “center range of the optical element” means that the distance from both ends of the optical element OE to the center of gravity Go is 0.9 B or more and 1.1 B, where B is the distance from the both ends of the optical element OE to the center thereof. Or the center of gravity Go from the optical axes X1 and X2 when the distance from the optical axis X1 of the first objective lens section OL1 and the optical axis X2 of the second objective lens section OL2 to the center thereof is C. The distance up to 0.9C or more and 1.1C or less satisfies the case where at least one of them is satisfied.

  An optical element for an optical pickup device according to a second aspect of the present invention is the optical device according to the first aspect, wherein the balance adjusting means is on the axis of the first objective lens portion and the second objective lens portion. Since the weight is provided on the optical element on the side where the thickness is thin, the above-described effects can be obtained.

  According to a third aspect of the present invention, there is provided an optical element for an optical pickup device according to the first aspect of the present invention, wherein the weight is formed integrally with the optical element. An optical element can be provided. The first objective lens portion and the second objective lens portion often have different axial thicknesses depending on the combination of optical information recording media to be used. That is, since the axial thickness is determined at the design stage, the shape of the molding die can be determined so that the position of the center of gravity can be set at the center of the optical element OE. However, a weight such as an iron-based metal having a specific gravity larger than that of the resin material forming the optical element may be separately attached to the optical element.

  The optical element for an optical pickup device according to a fourth aspect of the present invention is the optical device according to the first aspect, wherein the balance adjusting means is on the axis of the first objective lens portion and the second objective lens portion. It is a notch or an opening provided in the optical element on the thick side.

  In FIG. 7, the optical element OE has symmetrically formed notches FL2 as balance adjusting means at the end of the flange portion FL on the first objective lens portion OL1 side, instead of providing a build-up portion. By forming such a notch FL2 on the first objective lens portion OL1 side having a large axial thickness and a large volume, the center of gravity Go of the optical element OE can be positioned within the central range of the optical element OE. . More specifically, in FIG. 7, the distance AGo (2) from the attachment position of the left wire W to the center of gravity Go is equal to the distance AGo (1) from the attachment position of the right wire W to the center of gravity Go (AGo). It is preferable that (1) = AGo (2) = A) or a slight difference (within the center range of the optical element OE). In this case, if the rectangular opening RAP of the bobbin BB is located at the center thereof, the total center of gravity Gt of the optical element OE and the bobbin BB is in the vicinity of the bobbin BB with the optical element OE mounted on the bobbin BB. Will exist. Furthermore, if an overhanging portion BB1 corresponding to the notch FL2 of the optical element OE is formed at the corner of the opening RAP of the bobbin BB, assembly in the reverse direction between the bobbin BB and the optical element OE can be prevented. An opening may be provided instead of the notch.

  An optical element for an optical pickup device according to a fifth aspect is the optical device according to any one of the first to fourth aspects, wherein the optical surfaces of the first objective lens portion and the second objective lens portion are refractive surfaces. It consists of only.

  An optical element for an optical pickup device according to a sixth aspect is the optical device according to any one of the first to fourth aspects, wherein the optical surfaces of the first objective lens portion and the second objective lens portion have a diffractive structure. It is characterized by having.

  An optical element for an optical pickup device according to a seventh aspect is characterized in that, in the invention according to any one of the first to sixth aspects, a center of gravity of the optical element is in a central range thereof.

  An optical pickup device according to an eighth aspect uses the optical element according to any one of the first to seventh aspects.

  According to the present invention, it is possible to provide an optical element and an optical pickup device for an optical pickup device that can use different types of optical discs and can accurately drive a lens.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The optical pickup device PU1 according to the present embodiment can be incorporated in an optical disk drive device. FIG. 8 is a diagram showing a schematic configuration of the optical pickup device PU1.

  The optical pick-up device PU1 emits a 407 nm blue-violet laser beam (first beam) and emits a 407 nm blue-violet laser beam (first beam) when recording / reproducing information with respect to the BD and HD, and Second emission point EP2 (second light source) that emits a 655 nm laser beam (second beam) when recording / reproducing information on a DVD, and BD and HD information recording surfaces RL1 and RL2 A laser module LM and a CD including a first light receiving unit DS1 that receives a reflected light beam from the first light receiving unit DS2, a second light receiving unit DS2 that receives a reflected light beam from the information recording surface RL3 of the DVD, and a prism PS. A light source / light receiving unit integrated light source unit in which a third light source that emits a 785 nm laser beam (third beam) and a photodetector are integrated when information is recorded / reproduced. A hologram laser HL, has a collimator COL is the magnification variable element, an optical element OE, which is driven by an actuator AC1. The optical element OE includes a first objective lens section OL1 and a second objective lens section OL2 each having an optical surface composed only of a refractive surface. However, a diffractive structure may be formed on one of the optical surfaces of the first objective lens section OL1 and the second objective lens section OL2.

  FIG. 9 is a perspective view of the actuator AC1 that drives the optical element OE according to the present embodiment. A plate-like base 1 that also serves as a yoke is fixed to a housing of an optical pickup device (not shown). A housing 2 is fixed on the base 1. A substrate 3 is attached to the front side in the figure of the housing 2. One end of a total of six wires 4 is fixed to the substrate 3 in this example, three on each side, and the wires 4 on each side are arranged in parallel at equal intervals in the vertical direction and along the base 1. It is extended. The other end of the wire 4 is soldered to a fixture 14 attached to the side surface of the bobbin BB. The wire 4 has a function of movably supporting the bobbin BB with respect to the base 1 and a function of supplying power to a coil to be described later from a substrate 3 to which wiring (not shown) is connected. The casing 2 is filled with a gel (not shown) having a damping effect for the wire 4.

  The resin bobbin BB is mounted while adjusting the position of the center of gravity by shifting the optical element OE formed with the built-up portion FL1 as a balance adjusting means (see FIG. 6). The first objective lens section OL1 and the second objective lens section OL2 of the optical element OE are used for condensing a laser beam on the information recording surface of the optical disc in the optical pickup device of FIG. The bobbin BB has two rectangular openings 5a and 5b on the front side in the figure, and further has a weight 5c adjacent to the rectangular openings 5a and 5b. Note that the bobbin BB connects the optical element OE side and the opposite side to the column portions 5d and 5e disposed on both sides of the rectangular opening 5a, and the columns disposed on both sides of the rectangular opening 5b. It can be said that it is connected with the parts 5e and 5f. With such a configuration, even if the cross-sectional area of the rectangular openings 5a and 5b is relatively large, the rigidity of the bobbin BB can be ensured high.

  In the rectangular opening 5a, a pair of magnets 9A and 10A backed by the yokes 7A and 8A are disposed opposite to each other. The first coil group G1 is arranged so as to wind around the magnet 9A and the yoke 7A. Between the first coil group G1 and the magnet 10A, a tracking coil 11A wound so that the first coil group G1 and the winding axis are orthogonal to each other is disposed.

  On the other hand, in the rectangular opening 5b, a pair of magnets 9B and 10B backed by the yokes 7B and 8B are disposed opposite to each other. The second coil group G2 is arranged so as to wind around the magnet 9B and the yoke 7B. Between the second coil group G2 and the magnet 10B, a tracking coil 11B wound so that the second coil group G2 and the winding axis are orthogonal to each other is disposed. The first coil group G1 is attached to the rectangular opening 5a via a holding body 15A that holds both sides thereof, and the second coil group G2 is attached to the rectangular opening 5b via a holding body 15B that holds both sides thereof. It has been. Each of the coil groups G1 and G2 has an outer coil and an inner coil wound around two layers.

  Next, the operation of the actuator AC1 according to the present embodiment will be described. When power is supplied through the wire 4, current flows in the same direction (here, clockwise) in the outer coils of the coil groups G 1 and G 2. Therefore, according to Fleming's left-hand rule, , A magnetic force directed upward in the figure is generated. Accordingly, the bobbin BB to which the first coil group G1 and the second coil group G2 are fixed moves upward in the drawing, thereby realizing the focusing operation by moving the optical element OE in the optical axis direction. Can do. If the direction of the current is reversed, the bobbin BB moves downward.

  On the other hand, when a current flows in the clockwise direction in one of the coil groups G1 and G2 and a current flows in the counterclockwise direction in the other inner coil, Fleming's left-hand rule One of the inner coils generates a magnetic force upward in the figure, and the other inner coil generates a magnetic force downward in the figure. Therefore, a moment acts on the bobbin BB. Obviously, the moment can be set to an arbitrary value by changing the value of the current flowing through each inner coil, but it is preferable to set the moment to a current having the same absolute value but the opposite direction. By tilting the bobbin BB using this moment, the tilt adjustment of the optical element OE can be performed.

  Furthermore, by passing a current through the tracking coils 11A and 11B, the bobbin BB can be moved together with the optical element OE in a direction perpendicular to the optical axis, thereby performing a tracking operation.

  When recording / reproducing information with respect to the BD in the optical pickup device PU1, the bobbin BB is moved together with the actuator AC1 to the position shown in FIG. 8, and the first objective lens unit OL1 is inserted into the optical path. The first light emission point EP1 is caused to emit light. The divergent light beam emitted from the first light emitting point EP1 is converted into a parallel light beam by the collimator COL moved to the first position by the uniaxial actuator AC2, as shown by the solid line in FIG. After passing through the beam splitter BS and entering the first objective lens section OL1 in the state of parallel light, the light beam that has passed through the first effective diameter region is on the information recording surface RL1 via the protective substrate PL1 of the BD. However, since the light beam that has passed through the first effective diameter region becomes over-flare light, the diaphragm function is exhibited. The first objective lens section OL1 is driven together with the bobbin BB by the actuator AC1 to perform focusing and tracking.

  The reflected light flux modulated by the information pits on the information recording surface RL1 is transmitted again through the first objective lens section OL1, the beam splitter BS, and the collimator COL, and then enters the laser module LM, and then is reflected twice in the prism. Then, the light converges to the first light receiving unit DS1. And the information recorded on BD can be read using the output signal of 1st light-receiving part DS1. Spherical aberration caused by temperature changes during BD recording / reproduction and spherical aberration caused by using a two-layer disc are corrected by driving the collimator COL.

  In the optical pickup device PU1, when recording / reproducing information with respect to the HD, the bobbin BB is moved upward from the position shown in FIG. 8 and the second objective lens section OL2 is inserted into the optical path. One light emission point EP1 is caused to emit light. The divergent light beam emitted from the first light emitting point EP1 is converted into a parallel light beam by the collimator COL moved to the first position by the uniaxial actuator AC2, although the light beam path is omitted in FIG. After passing through the beam splitter BS and entering the second objective lens section OL2 in the state of parallel light, it becomes a spot formed on the information recording surface RL2 via the HD protective substrate PL2. Even in the second effective diameter region, the light beam that has passed through the region outside the effective diameter of HD becomes flare light due to the function of the diffraction structure and the like. In addition, since the light beam that has passed through the second effective diameter outside region becomes flare light, the diaphragm function is exhibited. The second objective lens section OL2 is driven by the actuator AC1 together with the bobbin BB to perform focusing and tracking.

  The reflected light flux modulated by the information pits on the information recording surface RL2 is again transmitted through the second objective lens section OL2, the beam splitter BS, and the collimator COL, then enters the laser module LM, and then is reflected twice in the prism. Then, the light converges to the first light receiving unit DS1. And the information recorded on HD can be read using the output signal of 1st light-receiving part DS1.

  In the second objective lens section OL2, the effective diameter for HD is smaller than the effective diameter for DVD. That is, when HD is used, flare light is generated by an optical surface area that is a diffractive surface used only for DVD, and when DVD is used, light passing through the area outside the maximum effective diameter becomes under-flare light. Thus, the aperture function is exhibited.

  In the optical pickup device PU1, when recording / reproducing information on a DVD, the bobbin BB is moved upward from the position shown in FIG. 8, the second objective lens section OL2 is inserted into the optical path, and The collimator COL is moved to the second position by the single-axis actuator AC2, and the second light emission point EP2 is caused to emit light. The divergent light beam emitted from the second light emitting point EP2 is converted into a weak divergent light beam by the collimator COL as shown by the two-dot chain line in FIG. After entering the objective lens section OL2 in the state of a finite divergent light beam, the light beam that has passed through the second effective diameter area (maximum effective diameter area) is formed on the information recording surface RL3 via the DVD protective substrate PL3. Become a spot. Further, since the light beam that has passed through the second effective diameter outside region becomes flare light, the diaphragm function is exhibited thereby. The objective lens section OL2 is driven together with the bobbin BB by the actuator AC1 to perform focusing and tracking.

  The reflected light flux modulated by the information pits on the information recording surface RL3 is again transmitted through the second objective lens section OL2, the beam splitter BS, and the collimator COL, then enters the laser module LM, and then is reflected twice in the prism. Then, the light converges to the second light receiving unit DS2. Then, information recorded on the DVD can be read using the output signal of the second light receiving unit DS2.

  When recording / reproducing information with respect to the CD in the optical pickup device PU1, the bobbin BB is moved upward in the drawing from the position shown in FIG. 8, and the second objective lens portion OL2 is inserted into the optical path. Then, the hologram laser HL is caused to emit light. The divergent light beam emitted from the hologram laser HL is reflected by the beam splitter BS and drawn in the state of a finite divergent light beam in the state of a finite divergent light beam, as depicted in FIG. From there, the spot is formed on the information recording surface RL4 via the CD protective substrate PL4. Even in the second effective diameter region, the light in the region outside the effective diameter of the CD becomes flare light due to the function of the diffraction structure and the like. Further, since the light beam that has passed through the second effective diameter outside region becomes flare light, the diaphragm function is exhibited thereby. The second objective lens section OL2 is driven by the actuator AC1 together with the bobbin BB to perform focusing and tracking.

  The reflected light flux modulated by the information pits on the information recording surface RL4 is reflected again by the second objective lens section OL2 and the beam splitter BS, then enters the hologram laser HL, and converges on the light receiving surface of the photodetector. And the information recorded on CD can be read using the output signal of a photodetector.

It is a perspective view of the comparative example which shows the tracking driven bobbin BB. It is a perspective view of the comparative example which shows the bobbin BB which carried out the tilt drive. It is a perspective view concerning a comparative example. It is a perspective view concerning a comparative example. FIG. 5A is a diagram showing the position of the center of gravity Go when the optical element OE is viewed from the front, and FIG. 5B is the position of the center of gravity Go when the optical element OE is viewed from the side. FIG. 5C is a diagram showing the position of the center of gravity Gb when the bobbin BB is viewed from the front, and FIG. 5D is the position of the center of gravity Gb when the bobbin BB is viewed from the side. FIG. It is a perspective view which shows an example of this invention, and shows in the state which decomposed | disassembled optical element OE. It is a perspective view which shows another example of this invention, and shows in the state which decomposed | disassembled optical element OE. It is a figure which shows schematically the structure of optical pick-up apparatus PU1. It is a perspective view of actuator AC1 which drives optical element OE concerning this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 Case 3 Board | substrate 4 Wire 5a Rectangular opening 5b Rectangular opening 5c Weight 5d Column part 5e Column part 7A Yoke 7B Yoke 9A Magnet 9B Magnet 10A Magnet 10B Magnet 11A Tracking coil 11B Tracking coil 14 Fixing body 15A Holding body 15A AC1 Actuator AC2 Single-axis actuator AP Opening BB Bobbin BB1 Notch BS Beam splitter CL Coil COL Collimator DP Diffraction plate DS1 First light receiving part DS2 Second light receiving part EP1 First light emitting point EP2 Second light emitting point FL Flange part FL1 Overlaying portion FL2 Notch G1 First coil group G2 Second coil group Gt Total center of gravity HL Hologram laser LM Laser module OL1 First objective lens portion OL2 Second objective lens portion PL1 Protection substrate PL2 Protection substrate PL3 Mamoru substrate PL4 protective substrate PS prism PU1 optical pickup apparatus RAP rectangular opening RL1 information recording surface RL2 information recording surface RL3 information recording surface RL4 information recording surface

Claims (8)

A single or a plurality of light sources, and an optical element in which a first objective lens portion and a second objective lens portion having different axial thicknesses are integrally formed, and the light flux from the light source is changed to the first light source. By focusing on the information recording surface of the first optical information recording medium via the objective lens unit, information can be recorded and / or reproduced on the information recording surface. An optical element for an optical pickup device that is capable of recording and / or reproducing information on the information recording surface by condensing on the information recording surface of the second optical information recording medium via the objective lens unit Because
An optical element for an optical pickup device, wherein the optical element has a balance adjusting means.   2. The balance adjusting means is a weight provided on the optical element on a side of the first objective lens portion and the second objective lens portion having a thin axial thickness. An optical element for the optical pickup device described in 1.   The optical element for an optical pickup device according to claim 2, wherein the weight is formed integrally with the optical element.   The balance adjusting means is a notch or an opening provided in the optical element on the thicker side on the axial side of the first objective lens part and the second objective lens part. Item 5. An optical element for an optical pickup device according to Item 1.   6. The optical element for an optical pickup device according to claim 1, wherein the optical surfaces of the first objective lens portion and the second objective lens portion are composed only of refractive surfaces.   6. The optical element for an optical pickup device according to claim 1, wherein the optical surfaces of the first objective lens section and the second objective lens section have a diffractive structure.   The optical element for an optical pickup device according to claim 1, wherein a center of gravity of the optical element is within a center range thereof.   An optical pickup device using the optical pickup device according to claim 1.

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