JP2006107707A - Optical pickup and disk drive apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup which can be designed with ease and can be efficiently moved. <P>SOLUTION: An objective lens drive apparatus 8 is provided with a fixed block 10 fixedly mounted on a movable base 7 and a movable block 11 holding a first objective lens 16 and a second objective lens 17 arranged separately in a tangential direction of recording tracks which is perpendicular to the focusing direction and the tracking direction, a laser beam is converged on a recording surface of at least one side of a digital versatile disk 100a or a compact disk 100b by the first objective lens, a laser beam is converged on a recording surface of a Blue-ray Disk 100c by the second objective lens, a lens center S2 of the second objective lens is positioned on a line Lr passing through the center P of the disk type recording medium loaded in a disk table 3 and extended in the radial direction of a disk type recording medium, a lens center S1 of the first objective lens is positioned on a line Lt passing through a lens center of the second objective lens and extended in the tangential direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical pickup and a disk drive device. More specifically, the present invention relates to a technical field of an optical pickup having an objective lens driving device that holds two objective lenses and a disk drive device that includes the optical pickup and that can use a plurality of types of disks.

  2. Description of the Related Art There is a disk drive device that records and reproduces information signals on and from a disk-shaped recording medium such as an optical disk and a magneto-optical disk. An optical pickup for irradiating the recording medium with laser light is provided.

  The optical pickup is provided with an objective lens driving device, and the objective lens driving device moves the objective lens held by the movable block in a focusing direction, which is a direction in which the recording surface of the disc-shaped recording medium is separated from and contacting the optical pickup. Focusing adjustment is performed and the objective lens is moved in the tracking direction, which is substantially the radial direction of the disk-shaped recording medium, to perform tracking adjustment, and the spot of the laser beam irradiated to the disk-shaped recording medium through the objective lens is recorded in the disk-shaped recording. The light is focused and followed by the recording track of the medium.

  On the other hand, various types of disc-shaped recording media have been developed in recent years due to differences in recording density, cover thickness, and the like. As such disc-shaped recording media, for example, a compact in which the wavelength used for laser light is around 780 nm There are a disc (CD: Compact Disc), a digital versatile disc (DVD: Digital Versatile Disc) having a use wavelength of around 660 nm, and a Blu-ray Disc (BD: Blu-ray Disc) having a use wavelength of around 405 nm.

  As an optical pickup for recording and reproducing information signals to and from a plurality of types of disc-shaped recording media having different laser light wavelengths, two objective lenses corresponding to the plurality of disc-shaped recording media are provided. (See, for example, Patent Document 1).

  In the optical pickup described in Patent Document 1, laser beams having different wavelengths are condensed on the recording surface of each disk-shaped recording medium by two objective lenses, and information signals are recorded on each disk-shaped recording medium. Playback is performed.

The two objective lenses are arranged on the movable block so as to be separated from each other in the radial direction of the disk-shaped recording medium, that is, in the tangential direction of the recording track, which is the direction orthogonal to the moving direction of the optical pickup. By arranging the two objective lenses so as to be separated in the tangential direction in this way, a good balance of the movable blocks in the radial direction of the disc-shaped recording medium is secured, and the characteristics of the objective lens driving device can be maximized. It becomes possible.
JP-A-9-35304

  By the way, depending on the type of the disk-shaped recording medium, the position of the recording track on the innermost circumference of the disk-shaped recording medium may be different. Therefore, it is desirable to design the optical pickup in consideration of this.

  As described above, in the optical disk drive, recording and reproduction can be performed on two types of optical disks, CD and DVD, and BD can be used together with CD and DVD. The optical disc drive has been put into practical use.

  However, as described above, the wavelength of the laser beam for Blu-ray Disc is 405 [nm], and the wavelength of the laser beam for CD or DVD is greatly different. It is difficult. For this reason, in an optical disk drive compatible with three wavelengths, it is realistic to provide two objective lenses for a Blu-ray disc and a CD / DVD on the optical pickup.

  Here, if the optical path for the Blu-ray disc and the optical path for the CD / DVD are completely separated, the apparatus design becomes easy, but there is a problem that the size of the optical pickup becomes large. For this reason, in a three-wavelength optical pickup, two objective lenses for Blu-ray Disc and CD / DVD are mounted on a single biaxial actuator, and the laser light supplied from the respective optical paths for Blu-ray Disc and CD / DVD. Can be introduced into the corresponding objective lens.

  Even in this case, two rise-up mirrors for introducing the laser beam into the objective lens are required for the Blu-ray disc and the CD / DVD. However, in practice, the biaxial actuator has a complicated structure composed of a lens support mechanism, a driving coil, and the like, so that the range of laser light introduction to the biaxial actuator is limited. In particular, a thin optical disk drive (so-called slim drive) mounted on a notebook computer limits the thickness of the entire device, further limiting the range of laser light introduction, which makes it difficult to reduce the thickness of the optical pickup itself. There was a problem of being.

  Therefore, an optical pickup and a disk drive device according to the present invention overcome the above-described problems, facilitate the design of the optical pickup and improve the movement efficiency, and the like, and an optical pickup having a thin and small structure corresponding to a plurality of wavelengths. An optical disk drive is to be proposed.

  A fixed block fixed to the moving base in the objective lens driving device, a focusing direction which is a direction in which the fixed block is separated from and contacting the recording surface of the disk-shaped recording medium, and a tracking direction which is a substantially radial direction of the disk-shaped recording medium A first objective lens and a movable block for holding the second objective lens, which are spaced apart from each other in the tangential direction of the recording track perpendicular to both the focusing direction and the tracking direction. The first laser beam is condensed on the recording surface of the disc-shaped recording medium by the lens, and the disc-shaped recording medium is different from the disc-shaped recording medium in which the first laser beam is condensed by the second objective lens. The second laser beam having a wavelength shorter than that of the first laser beam is condensed on the recording surface, and the first objective lens or the second objective is collected. The lens center of the first objective lens is positioned on a segment extending in the radial direction of the disk-shaped recording medium through the center of the disk-shaped recording medium mounted on the disk table, and the lens center of the first objective lens is the center of the second objective lens. It is positioned on a line segment that passes through the center of the lens and extends in the tangential direction.

  Therefore, in the optical pickup and the disk drive device according to the present invention, the movement of the optical pickup toward the side closer to the spindle motor is minimized.

  In the present invention, the first laser light source that emits the first laser light and the first objective lens that emits the first laser light to the optical disc corresponding to the wavelength of the first laser light. A second laser light source that emits a second laser light having a wavelength different from that of the first laser light, and a second laser light source that emits the second laser light to the optical disc corresponding to the wavelength of the second laser light. The second objective lens, a first optical path for guiding the first laser light from the first laser light source to the first objective lens, and a second laser light for guiding the second laser light from the second laser light source to the second objective lens. Optical path separation for separating the second optical path, optical path combining means for combining a part of the first and second optical paths, and the combined optical path combined by the optical path combining means at the front stage of the first and second objective lenses Means for the optical pickup .

  The first objective lens and the second objective lens are provided in the same biaxial actuator, and the optical path synthesizing unit is configured so that the first and second laser beams are arranged on the optical path before the first and second laser beams are introduced into the biaxial actuator. The first and second optical paths are synthesized.

  The first and second optical paths are made common in front of the biaxial actuator, and further separated at the front stage of the first and second objective lenses, so that the two-axis structure with a thin structure that limits the introduction range of laser light is limited. An optical pickup having a thin structure corresponding to a plurality of wavelengths can be formed using an actuator.

  An optical pickup according to the present invention includes a moving base that is moved in a radial direction of a disk-shaped recording medium that is mounted on a disk table, and an objective lens driving device that is disposed on the moving base, and a use wavelength mounted on the disk table. An optical pickup that emits laser beams of at least two types of wavelengths corresponding to different disk-shaped recording media, wherein the objective lens driving device includes a fixed block fixed to the moving base, and a fixed block to the fixed block. On the other hand, it is operated in the focusing direction, which is the direction in which the recording surface of the disk-shaped recording medium is separated from the recording surface, and in the tracking direction, which is the substantially radial direction of the disk-shaped recording medium, and in the tangential direction of the recording track which is orthogonal Holds a first objective lens and a second objective lens that are spaced apart A movable block, wherein the first objective lens condenses the first laser beam on the recording surface of the disc-shaped recording medium, and the second objective lens condenses the first laser beam. A second laser beam having a wavelength shorter than that of the first laser beam is condensed on a recording surface of a disc-shaped recording medium of a type different from the disc-shaped recording medium, and the lens center of the second objective lens is a disc table. Is positioned on a line segment extending in the radial direction of the disc-shaped recording medium through the center of the disc-shaped recording medium, and the lens center of the first objective lens passes through the lens center of the second objective lens and is tangent It is characterized by being positioned on a line segment extending in the direction.

  Therefore, the moving end of the optical pickup closer to the disk table can be set at a position farthest away from the spindle motor, and it is easy to design to avoid contact between the moving base and the spindle motor. And manufacturing cost can be reduced.

  In addition, the amount of movement of the optical pickup closer to the disk table can be minimized, and the efficiency of movement of the optical pickup can be improved.

  The disk drive device of the present invention includes a moving base that is moved in the radial direction of a disk-shaped recording medium that is mounted on the disk table, and an objective lens driving device that is disposed on the moving base, and a working wavelength mounted on the disk table. A disk drive device configured to irradiate at least two types of laser beams corresponding to different disk-shaped recording media, wherein the objective lens driving device is a fixed block fixed to the moving base Are moved in a focusing direction which is a direction in which the fixed block is separated from and contacting the recording surface of the disk-shaped recording medium and a tracking direction which is a substantially radial direction of the disk-shaped recording medium, and are orthogonal to both the focusing direction and the tracking direction. The first objective lens that is spaced apart in the tangential direction of the recording track A movable block for holding a second objective lens, wherein the first objective lens condenses the first laser beam on the recording surface of the disc-shaped recording medium, and the second objective lens is the first objective lens. A second laser beam having a wavelength shorter than that of the first laser beam is condensed on a recording surface of a disc-shaped recording medium of a type different from the disc-shaped recording medium on which the laser beam is condensed, and the second laser beam is collected. The lens center of the objective lens is positioned on a segment extending in the radial direction of the disk-shaped recording medium through the center of the disk-shaped recording medium mounted on the disk table, and the lens center of the first objective lens is the second objective. It is characterized by being positioned on a line segment passing through the lens center and extending in the tangential direction.

  Therefore, the moving end of the optical pickup closer to the disk table can be set at a position farthest from the spindle motor, and the design for avoiding contact between the moving base and the spindle motor is easy. It is possible to facilitate design and reduce manufacturing costs.

  In addition, the amount of movement of the optical pickup closer to the disk table can be minimized, and the efficiency of movement of the optical pickup can be improved.

  Further, according to the present invention, the first and second optical paths are made common in front of the biaxial actuator, and further separated at the front stage of the first and second objective lenses, so that the laser light introduction range can be obtained. An optical pickup corresponding to a plurality of wavelengths can be configured by using a thin-structured biaxial actuator with a limited thickness, and thus a thin-structure optical pickup and an optical disk drive corresponding to a plurality of wavelengths can be realized.

(1) First Embodiment Hereinafter, the best mode of an optical pickup and a disk drive device of the present invention will be described with reference to the accompanying drawings.

  The disk drive device 1 is configured by arranging required members and mechanisms in an outer casing 2 (see FIG. 1), and the outer casing 2 has a disk insertion slot (not shown).

  A chassis (not shown) is disposed in the outer casing 2, and the disk table 3 is fixed to the motor shaft of a spindle motor attached to the chassis.

  Parallel guide shafts 4 and 4 are attached to the chassis, and a lead screw 5 that is rotated by a feed motor (not shown) is supported.

  The optical pickup 6 includes a moving base 7, required optical components provided on the moving base 7, and an objective lens driving device 8 disposed on the moving base 7, and is provided at both ends of the moving base 7. The bearing portions 7a and 7b are slidably supported by the guide shafts 4 and 4, respectively.

  When a nut member (not shown) provided on the moving base 7 is screwed into the lead screw 5 and the lead screw 5 is rotated by the feed motor, the nut member is sent in a direction corresponding to the rotation direction of the lead screw 5, The pickup 6 is moved in the radial direction of the disc-shaped recording medium 100 mounted on the disc table 3.

  As the disc-shaped recording medium 100, in addition to a digital versatile disc (DVD) 100a and a compact disc (CD) 100b, a Blu-ray disc (BD) 100c is used. The operating wavelengths of the laser light of each of these disk-shaped recording media 100 are about 660 nm for the DVD 100a, about 780 nm for the CD 100b, and about 405 nm for the BD 100c.

  In the disc-shaped recording medium 100, generally, information such as images, music, characters, etc. is written, a first writing area called an information area, and various types and configurations of the disc-shaped recording medium 100, etc. Medium information is written, and a second writing area called a burst cutting area or a transition area is provided. The second writing area is a writing area that is formed inside the first writing area and exists on the innermost peripheral side of the disc-shaped recording medium 100.

  The innermost recording track of the second writing area differs depending on the type of the disc-shaped recording medium 100, and is about 22 mm from the center in the DVD 100a and the CD 100b, and about 21 mm from the center in the BD 100c. It has been known.

  When a recording operation or a reproducing operation is performed in the disk drive device 1, information recorded in the second writing area existing on the inner peripheral side is first read, and then the outside of the second writing area The information is written into the first writing area existing in the memory or the information recorded in the first writing area is read. Therefore, when the recording operation or the reproducing operation for the DVD 100a and the CD 100b is performed, the information of the recording track existing at a position of about 22 mm from the center is first read, and when the recording operation or the reproducing operation for the BD 100c is performed, the information is first started from the center. Information of a recording track existing at a position of about 21 mm is read out.

  The objective lens driving device 8 includes a base member 9, a fixed block 10, and a movable block 11 operated with respect to the fixed block 10 (see FIGS. 2 and 3).

  The base member 9 is made of a magnetic metal material, and includes a base portion 9a fixed on the moving base 7 and yoke portions 9b and 9b bent upright at right angles from the base portion 9a. The yoke portions 9b and 9b are provided apart from each other in the front-rear direction, that is, in the tangential direction (TAN) of the recording track of the disc-shaped recording medium 100.

  Magnets 12 and 12 are attached to the surfaces of the yoke portions 9b and 9b facing each other.

  The fixed block 10 is fixed to the moving base 7. One end of a circuit board (not shown) is attached to the rear surface of the fixed block 10, and the circuit board is connected to a power supply circuit (not shown).

  The rear ends of the support springs 13, 13,... Are connected to the fixed block 10, and the support springs 13, 13,... Are connected to a circuit board attached to the rear surface of the fixed block 10. Yes. The support springs 13, 13,... Protrude forward from the fixed block 10.

  The movable block 11 has a movable holder 14 and a drive coil 15.

  The movable holder 14 is formed by integrally forming a lens mounting portion 14a and a coil holding portion 14b provided on the rear side of the lens mounting portion 14a.

  The lens mounting portion 14a is formed with transmission holes 14c and 14d that are separated from each other in the front-rear direction (see FIG. 3). The first objective lens 16 and the second objective lens 16 are covered with the transmission holes 14c and 14d from above. An objective lens 17 is attached.

  The first objective lens 16 has a configuration corresponding to laser beams of about 660 nm and about 780 nm, each having a numerical aperture of about 0.5 to 0.65, and applies laser light to the recording surface of the DVD 100a or CD 100b. It plays the role of condensing.

  The second objective lens 17 has a configuration corresponding to about 405 nm laser light, has a numerical aperture of about 0.85, and plays a role of condensing the laser light on the recording surface of the BD 100c.

  The second objective lens 17 is disposed closer to the fixed block 10 than the first objective lens 16. As shown in FIG. 4, in the second objective lens 17, the lens center S2 extends in the moving direction of the optical pickup 6, that is, in the radial direction of the disk-shaped recording medium 100, and the rotation center of the disk table 3 (disk-shaped recording medium). 100 corresponding to the line segment Lr passing through the center P).

  The first objective lens 16 is arranged away from the second objective lens 17 in the tangential direction of the recording track of the disc-shaped recording medium 100, and the lens center S1 of the first objective lens 16 is the second objective lens 16. It is positioned corresponding to a line segment Lt that passes through the lens center S2 of the objective lens 17 and extends in the tangential direction.

  Therefore, as shown in FIG. 5, the distance H1 from the center P of the disc-shaped recording medium 100 to the lens center S1 of the first objective lens 16 is the center P of the disc-shaped recording medium 100. The distance H2 is larger than the distance H2 to the lens center S2.

  The coil holding portion 14b of the movable block 11 is formed in a substantially rectangular frame shape penetrating vertically, and the drive coil 15 is held inside the coil holding portion 14b (see FIGS. 2 and 3).

  The drive coil 15 includes a focusing coil 18 for operating the movable block 11 in the focusing direction, and tracking coils 19 and 19 for operating the movable block 11 in the tracking direction. The focusing direction is the direction in which the disc-shaped recording medium 100 is separated from or contacted (F direction shown in FIG. 3), that is, the vertical direction, and the tracking direction is the radial direction of the disc-shaped recording medium 100 (T direction shown in FIG. 2). Left and right direction.

  The focusing coil 18 and the tracking coils 19 and 19 are each formed by being wound in a substantially rectangular tube shape. The focusing coil 18 has a winding direction in the vertical direction (focusing direction), and the tracking coils 19 and 19 have a winding direction in the winding direction. It is set as the front-back direction (tangential direction). The tracking coils 19, 19 are provided on the front surface of the focusing coil 18 so as to be separated from each other in the left-right direction.

  One end portions of the focusing coil 18 and the tracking coils 19 and 19 are connected to connection terminal portions 14e, 14e,... Provided on both side surfaces of the movable holder 14, respectively. The front end portions of the support springs 13, 13,... Are connected to the connection terminal portions 14e, 14e,. Therefore, the movable block 11 is connected to the fixed block 10 by the support springs 13, 13,.

  A driving current for focusing adjustment or tracking adjustment is supplied to the support springs 13, 13... Via a circuit board attached to the rear surface of the fixed block 10 from the power supply circuit. Accordingly, two of each of the support springs 13, 13,... Function as power feeding members to the focusing coil 18 and the tracking coils 19, 19.

  Magnets 12 and 12 attached to the yoke portions 9b and 9b are disposed at positions on both sides of the front and rear of the tracking coils 19 and 19, respectively.

  When a driving current is supplied from the power supply circuit to the focusing coil 18 or the tracking coils 19, 19,... Via the circuit board and the support springs 13, 13,. 12, the movable block 11 is moved in the focusing direction or the tracking direction according to the direction of the magnetic flux generated by the yoke portions 9b and 9b.

  When the movable block 11 is moved in the focusing direction or the tracking direction, the support springs 13, 13, ... are elastically deformed.

  Below the first objective lens 16 and the second objective lens 17 provided on the movable holder 14, a beam splitter 20 and a rising mirror 21 are arranged, respectively (see FIG. 3). The beam splitter 20 and the raising mirror 21 are arranged on the moving base 7 with the separation surface 20a and the reflection surface 21a in the same direction. The separation surface 20a of the beam splitter 20 is formed of a transmissive film having a wavelength dependency with different transmittance depending on the wavelength.

  In the disk drive device 1 configured as described above, when the disk table 3 is rotated with the rotation of the spindle motor, the disk-shaped recording medium 100 mounted on the disk table 3 is rotated.

  At this time, when the disc-shaped recording medium 100 mounted on the disc table 3 is a DVD 100a or a CD 100b, the laser light emitted from a light emitting element (not shown) and incident on the beam splitter 20 is separated from the separation surface 20a of the beam splitter 20. And is irradiated onto the recording surface of the DVD 100 a or CD 100 b through the first objective lens 16. The laser light applied to the recording surface of the DVD 100a or the CD 100b is reflected by the recording surface, and is incident on a light receiving element (not shown) via the first objective lens 16 and the beam splitter 20 again as return light. When the return light is incident on the light receiving element, each signal such as an RF signal is detected, and an information signal is recorded on or reproduced from the DVD 100a or CD 100b.

  On the other hand, when the disc-shaped recording medium 100 mounted on the disc table 3 is a BD 100c, laser light emitted from a light emitting element (not shown) and incident on the beam splitter 20 is transmitted through the separation surface 20a of the beam splitter 20. Then, the light is reflected by the reflecting surface 21 a of the rising mirror 21 and irradiated onto the recording surface of the BD 100 c through the second objective lens 17. The laser light applied to the recording surface of the BD 100c is reflected by the recording surface and is incident on the light receiving element again as the return light through the second objective lens 17, the rising mirror 21, and the beam splitter 20. When return light is incident on the light receiving element, each signal such as an RF signal is detected, and an information signal is recorded on or reproduced from the BD 100c.

  In the recording operation and the reproducing operation described above, when a driving current is supplied to the focusing coil 18, the movable block 11 of the objective lens driving device 8 is operated in the focusing direction with respect to the fixed block 10 as described above. Focusing adjustment is performed so that the spot of the laser beam emitted from the laser beam and irradiated through the first objective lens 16 or the second objective lens 17 is focused on the recording track of the disc-shaped recording medium 100.

  When a driving current is supplied to the tracking coils 19, 19, the movable block 11 of the objective lens driving device 8 is operated in the tracking direction with respect to the fixed block 10 as described above, and the first light is emitted from the light emitting element. Tracking adjustment is performed so that the spot of the laser light irradiated through the objective lens 16 or the second objective lens 17 follows the recording track of the disc-shaped recording medium 100.

  In the recording operation and the reproducing operation, the optical pickup 6 is moved from the inner circumference side to the outer circumference side of the disc-shaped recording medium 100. At this time, when the disc-shaped recording medium 100 is a DVD 100a or a CD 100b, as described above, information on the recording track Tdc (see FIG. 4) existing at a position of about 22 mm from the center first passes through the first objective lens 16. When the disc-shaped recording medium 100 is a BD 100c, information on the recording track Tb (see FIG. 4) existing at a position of about 21 mm from the center is first read out via the second objective lens 17. It is.

  In the optical pickup 6, the lens center S2 of the second objective lens 17 for the BD 100c corresponds to a line segment Lr extending in the radial direction of the disc-shaped recording medium 100 and passing through the center P of the disc-shaped recording medium 100. The lens center S1 of the first objective lens 16 for the DVD 100a and the CD 100b is positioned corresponding to a line segment Lt extending in the tangential direction of the recording track of the disc-shaped recording medium 100 through the lens center S2.

  Accordingly, when the lens center S2 of the second objective lens 17 is positioned corresponding to the recording track Tb existing on the innermost circumference of the BD 100c, the lens center S1 of the first objective lens 16 is outside the recording track Tb. Located in. Even if this position of the optical pickup 6 is set to the moving end on the side approaching the disk table 3, the information recorded on the recording track Tdc existing on the innermost periphery of the DVD 100a or CD 100b can be read.

  Conversely, the objective lens on the line segment Lr is set for the DVD 100a and the CD 100b, the other objective lens is set for the BD 100c, and the lens center of the objective lens on the line segment Lr is the innermost circumference of the DVD 100a or CD 100b. When the position corresponding to the recording track Tdc existing in the optical pickup 6 is set to the moving end on the side close to the disk table 3 of the optical pickup 6, the lens center of the other objective lens is located at the innermost circumference of the BD 100c at the moving end. Since it is positioned outside the existing recording track Tb, information recorded on the recording track Tb existing on the innermost periphery of the BD 100c cannot be read. Therefore, the position inside this position must be set as the moving end inside the optical pickup 6, and the amount of movement of the optical pickup 6 becomes large and more than necessary for the objective lens on the line segment Lr. Will be moved to.

  As described above, in the optical pickup 6, the first objective lens 16 for the DVD 100 a and the CD 100 b and the second objective lens 17 for the BD 100 c are separated in the tangential direction of the recording track of the disc-shaped recording medium 100. The lens center S2 of the second objective lens 17 is positioned on a line segment Lr extending in the radial direction of the disc-shaped recording medium 100 through the center P of the disc-shaped recording medium 100. The moving end of the optical pickup 6 on the side approaching the disk table 3 can be set at a position farthest from the spindle motor, and the design for avoiding contact between the moving base 7 and the spindle motor is easy, and the disk drive device The design can be facilitated and the manufacturing cost can be reduced.

  In addition, the amount of movement of the optical pickup 6 on the side approaching the disk table 3 can be minimized, and the efficiency of movement of the optical pickup 6 can be improved.

  In the optical pickup 6, when the tracking error signal is detected using the differential push-pull method, it is desirable that the positional relationship between the three spots on the recording surface of the laser beam and the recording track does not change. Since the curvature of the recording track differs between when the optical pickup 6 is moved to the inner peripheral side of the disc-shaped recording medium 100 and when it is moved to the outer peripheral side, the positional relationship between the three spots and the recording track is different. Change. This rate of change is greater than that of the laser beam irradiated through the second objective lens 17 positioned on the line segment Lr in which the lens center S2 passes through the center P of the disc-shaped recording medium 100 and extends in the radial direction. Becomes larger than the laser beam irradiated through the first objective lens 16 not located on the line segment Lr.

  Further, the distance between recording tracks, that is, the disc-shaped recording medium 100 having a small track pitch is easily affected by the positional relationship, and the BD 100c having a small track pitch has a larger effect than the DVD 100a and the CD 100b having a large track pitch. There is a fear.

  Therefore, as described above, the tracking error signal is detected by using the differential push-pull method by positioning the lens center S2 of the second objective lens 17 for the BD 100c on the line segment Lr. The error signal detection accuracy can be improved.

  In the optical pickup 6 described above, since the track pitch is small with respect to the BD 100c, a so-called three-spot method is used as a method for detecting a tracking error signal, which is not easily affected by disturbance using the main light beam and the sub light beam. It is desirable to use it.

  When the three-spot method is used as described above, the innermost and outermost circumferences of the BD 100c are obtained by positioning the lens center S2 of the second objective lens 17 for the BD 100c on the line segment Lr as described above. It becomes difficult to be affected by the offset that occurs in

  In addition, there is a method of detecting a tracking error signal using only one spot (main light beam) as compared with the three-spot method. Since this detection method uses only one spot, scratches on the recording surface of the disk-shaped recording medium 100 are detected. However, by using the three-spot method as described above, it is possible to reduce the influence of these scratches and dust.

  In the above, the first objective lens 16 for the DVD 100a and the CD 100b is disposed on the distal end side of the movable block 11, and the second objective for the BD 100c is disposed on the proximal end side of the movable block 11, that is, the side close to the fixed block 10. Although the example in which the lens 17 is arranged has been shown, conversely, as shown in FIG. 6, the second objective lens 17 for the BD 100c is arranged on the distal end side of the movable block 11, and is positioned on the line segment Lr to be movable. The second objective lens 17 for the DVD 100a and the CD 100b may be disposed at a position on the fixed block 10 side in the block 11.

  As for the first objective lens 16 and the second objective lens 17, which of the objective lens arrangement shown in FIG. 4 and the objective lens arrangement shown in FIG. What is necessary is just to determine in consideration of the ease of formation of the permeable film which comprises the surface 20a. For example, in the case where it is easy to form a transmission film that reflects laser light having wavelengths of about 660 nm and about 780 nm and transmits laser light having a wavelength of about 405 nm as the separation surface 20 a, The first objective lens 16 and the second objective lens 17 may be arranged. Conversely, laser light having a wavelength of about 405 nm is reflected and laser light having wavelengths of about 660 nm and about 780 nm is transmitted. When it is easy to form the permeable membrane as the separation surface 20a, the second objective lens 17 and the first objective lens 16 may be arranged in order from the distal end side of the movable block 11.

  In the above description, the disk drive device 1 that handles three types of disc-shaped recording media 100, that is, the DVD 100a, the CD 100b, and the BD 100c has been shown as an example. As the disc drive device, two types of disc-shaped recording media, the DVD 100a and the BD 100c 100 or two types of disc-shaped recording media 100, CD 100b and BD 100c, may be handled.

  In the above description, the focusing direction is the vertical direction and the tracking direction is the left-right direction. However, these directions are shown as examples for convenience of description, and are not particularly limited to these directions.

(2) Second Embodiment FIG. 7A shows a three-wavelength compatible optical pickup 110, which is configured by mounting various optical elements and the like on a base 111. The optical system in the optical pickup 10 is called a CD / DVD optical system 120 for performing recording / reproduction with respect to a CD and a DVD, and a BD optical system optical system for performing recording / reproduction with respect to a Blu-ray disc disc (hereinafter abbreviated as BD). ) 140, and a common optical system 160 that is commonly used for the CD, DVD, and BD.

(2-1) Configuration of CD / DVD Optical System In the CD / DVD optical system 120, the laser light emitted from the CD / DVD laser diode 121 as the first laser light source is used as the first laser light. The emitted light for CD / DVD enters the collimator lens 126 through the coupling lens 122, the mirror 123, the grating 124, and the beam splitter 125 in this order. The collimator lens 126 converts the emitted light for CD / DVD into parallel light and enters the common optical system 160.

  The optical path combining beam splitter 161 of the common optical system 160 reflects a part of the emitted light for CD / DVD at a right angle and enters the front photodiode 127 for laser power detection. As will be described in detail later, the common optical system 60 irradiates the recording surface of the optical disc 100 with the remainder of the emitted light for CD / DVD via the CD / DVD objective lens 162, and reflects the reflected light for CD / DVD. The incident light is received by the CD / DVD objective lens 162 and is incident on the CD / DVD optical system 120.

  Then, the CD / DVD optical system 120 makes the incident light for CD / DVD enter the beam splitter 125 via the collimator lens 126. The beam splitter 125 reflects CD / DVD incident light at a right angle, and enters a detection PDIC (Photo Detector IC) 130 via a cylindrical lens 128 and a hologram 129. The PDIC 130 photoelectrically converts incident light for CD / DVD and outputs various signals such as a reproduction signal, a tracking error signal, and a focus error signal.

(2-2) Configuration of BD Optical System On the other hand, in the BD optical system 140, the laser light emitted from the BD laser diode 141 as the second laser light source is used as the emitted light for BD as the second laser light. Then, the polarization plane is rotated by the polarization means 142 made of a wave plate, a grating, or a composite element thereof, and then enters the beam splitter 143.

  The beam splitter 143 transmits a part of the emitted light for BD, and enters the front photodiode 145 for laser power detection via the collimator lens 144. The beam splitter 143 reflects the remainder of the emitted light for BD and enters the collimator lens 148 through the beam splitter 146 and the mirror 147 in order. The collimator lens 148 converts the emitted light for BD into parallel light and enters the common optical system 160.

  The beam splitter 161 for synthesizing the optical path of the common optical system 160 reflects the emitted light for BD at a right angle, irradiates the recording surface of the optical disc 100 via the BD objective lens 163, and uses the reflected light as incident light for BD. The light is received by the BD objective lens 163 and enters the BD optical system 140.

  The BD optical system 140 causes the incident light for BD to enter the beam splitter 146 through the collimator lens 148 and the mirror 147 sequentially. The beam splitter 146 transmits the BD emission light and enters the detection PDIC 151 via the hologram 149 and the coupling lens 150. The PDIC 151 photoelectrically converts BD incident light and outputs various signals such as a reproduction signal, a tracking error signal, and a focus error signal.

(2-3) Configuration of Common Optical System Next, the configuration of the common optical system 160 that is a feature of the present invention will be described in detail. In this common optical system 160, the CD / DVD objective lens 162 and the BD objective lens 163 are mounted on the same biaxial actuator 168, and below the CD / DVD objective lens 162 and the BD objective lens 163. 1 includes a rising mirror unit 165 including a BD rising mirror 166 and a CD / DVD rising mirror 167.

  That is, as shown in FIG. 7B, a CD / DVD rising mirror 166 is provided below the CD / DVD objective lens 162, and a BD rising edge is provided below the BD objective lens 163. A mirror 167 is provided, and the optical path combining beam splitter 161, the BD rising mirror 167, and the CD / DVD rising mirror 166 are arranged in a straight line.

  As described above, in the common optical system 160, the emitted light for CD / DVD and the emitted light for BD are both incident on the beam path combining beam splitter 161 as optical path combining means. The common optical system 160 uses the CD / DVD outgoing light and the BD outgoing light transmitted through the optical path combining beam splitter 161 via a spherical aberration correcting liquid crystal element 164 as a BD rising mirror as an optical path separating means. 167 is incident.

  The BD rising mirror 167 is a wavelength-selective beam splitter, and reflects only blue-violet laser light having a wavelength of 405 [nm] for a Blu-ray disc by 90 °. Therefore, when the incident outgoing light is BD outgoing light, the BD rising mirror 167 reflects the BD outgoing light and raises it upward, and passes through the BD objective lens 163 to the optical disc 100 (in this case). The reflected light from the BD received through the BD objective lens 163 is incident on the BD optical system 140 through the liquid crystal element 164 and the optical path combining beam splitter 161.

  On the other hand, when the incident outgoing light is the outgoing light for CD / DVD, the BD rising mirror 167 transmits the outgoing light for CD / DVD and enters the rising mirror 66 for CD / DVD. The CD / DVD rising mirror 66 reflects the emitted light for CD / DVD, rises upward, and irradiates the optical disk 100 (in this case, CD or DVD) via the CD / DVD objective lens 162, as well as the CD / DVD. The reflected light from the CD or DVD received through the DVD objective lens 162 is incident on the CD / DVD optical system 120 through the BD rising mirror 167, the liquid crystal element 164, and the optical path combining beam splitter 161.

(3) Operation and Effect In the above configuration, in the optical pickup 110, the CD / DVD objective lens 162 and the BD objective lens 163 are mounted on the same biaxial actuator 168 and emitted from the CD / DVD optical system 120. Both the emitted light for CD / DVD and the emitted light for BD emitted from the BD optical system 140 are incident on the rising mirror section 165 via the beam splitter for optical path synthesis 161 of the common optical system 160. Then, the CD / DVD emission light and the BD emission light are separated by a BD rising mirror 167 formed of a wavelength selective beam splitter and emitted through a corresponding objective lens 162 or 163.

  In this way, the biaxial actuator that holds the objective lenses 162 and 163 by synthesizing the optical paths of the CD / DVD outgoing light and the BD outgoing light when entering the rising mirror unit 165 by the optical path synthesizing beam splitter 161. The optical paths of the CD / DVD emission light and the BD emission light with respect to 67 are made common. Accordingly, the three-wavelength compatible optical pickup 110 can be configured by using the thin biaxial actuator 167 in which the introduction range of the laser light is limited.

  According to the above configuration, a part of the optical path for CD / DVD and BD is shared by the beam splitter 161 for optical path synthesis, and further, the optical path for CD / DVD and BD is separated by the rising mirror unit 165. The thin and three-wavelength compatible optical pickup 110 is configured using the thin biaxial actuator 167 that limits the introduction range of the laser light by being incident on the corresponding objective lenses 162 and 163. Thus, the optical disc drive 1 having a thin structure corresponding to a plurality of wavelengths can be realized.

(4) Other Embodiments In the above-described embodiment, a part of the two optical paths for CD / DVD and BD is shared by the beam splitter 161 for optical path synthesis. Not limited to this, optical paths for CD, DVD, and BD may be provided separately, and a part of these three optical paths may be shared by the optical path combining beam splitter and introduced into the rising mirror unit 165. . Further, the optical disk to be used by the optical disk drive 1 is not limited to CD, DVD and BD, and can be applied to various optical disks.

  In the configuration of the common optical system 160 in FIG. 7B, the CD / DVD objective lens 162 and the BD objective lens 163 are arranged at opposite positions, and below the CD / DVD objective lens 162, A CD / DVD rising mirror 166 may be provided, and a BD rising mirror 167 may be provided below the BD objective lens 163. Also in this case, the beam path combining beam splitter 161, the BD rising mirror 167, and the CD / DVD rising mirror 166 may be arranged on a straight line.

  That is, as shown in FIGS. 3 and 4, the CD / DVD objective lens and the BD objective lens are arranged, and the CD / DVD outgoing light and the BD outgoing light transmitted through the optical path synthesis beam splitter 161 are changed into the optical path. It is configured to be incident on a CD / DVD rising mirror 166 as a separating means.

  The CD / DVD rising mirror 166 is a wavelength-selective beam splitter and transmits blue-violet laser light having a wavelength of 405 [nm] for a Blu-ray disc. Therefore, when the incident outgoing light is BD outgoing light, the CD / DVD startup mirror 166 transmits the BD outgoing light and enters the BD startup mirror 167. The BD start-up mirror 167 raises the BD output light by reflecting the output light and irradiates the optical disc 100 (in this case, a Blu-ray disc) via the BD objective lens 163 and also the BD objective lens 163. The reflected light from the BD received via the BD enters the BD optical system 140 via the liquid crystal element 164 and the optical path combining beam splitter 161.

  On the other hand, when the incident outgoing light is the outgoing light for CD / DVD, the CD / DVD rising mirror 166 reflects the outgoing light for CD / DVD by 90 °, rises upward, and the CD / DVD is raised. The optical disk 100 (in this case, CD or DVD) is irradiated through the objective lens 162 for use, and the reflected light from the CD or DVD received through the objective lens 162 for CD / DVD is converted into the BD rising mirror 167 and the liquid crystal. The light enters the CD / DVD optical system 120 via the element 164 and the beam splitter 161 for optical path synthesis.

  The specific shapes and structures of the respective parts shown in the best mode for carrying out the invention described above are merely examples of the implementation of the present invention, and the present invention is thereby limited. This technical scope should not be interpreted in a limited way.

2 to 6 show the best mode for carrying out the present invention, and this figure is a schematic perspective view of a disk drive device. FIG. It is a schematic enlarged plan view of an objective lens driving device. It is an expanded sectional view which shows a part of objective lens drive device. It is a conceptual diagram which shows the positional relationship of two objective lenses and a recording track. It is an enlarged view of the principal part in FIG. It is an enlarged plan view which shows the objective lens drive device from which the position of two objective lenses differs. It is a basic diagram which shows the structure of the optical pick-up by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Disc drive apparatus, 3 ... Disc table, 6 ... Optical pick-up, 7 ... Moving base, 8 ... Objective lens drive device, 10 ... Fixed block, 11 ... Movable block, 16 ... 1st Objective lens 17... Second objective lens.

Claims (6)

Each disk-shaped recording medium mounted on the disk table and having a different working wavelength includes a moving base moved in the radial direction of the disk-shaped recording medium mounted on the disk table and an objective lens driving device arranged on the moving base. Corresponding to the optical pickup that emits laser light of at least two types of wavelengths,
The objective lens driving device is:
A fixed block fixed to the moving base;
A recording track which is operated in a focusing direction which is a direction in which the fixed block is separated from and contacting the recording surface of the disk-shaped recording medium and a tracking direction which is a substantially radial direction of the disk-shaped recording medium and which is orthogonal to both the focusing direction and the tracking direction. Comprising a first objective lens and a movable block for holding the second objective lens, which are spaced apart in the tangential direction of
The first objective lens focuses the first laser beam on the recording surface of the disc-shaped recording medium,
The second objective lens has a second laser having a shorter wavelength than the first laser beam on a recording surface of a disc-shaped recording medium of a type different from the disc-shaped recording medium on which the first laser beam is condensed. Condensing light,
The lens center of the first objective lens or the second objective lens is positioned on a line segment extending in the radial direction of the disc-shaped recording medium through the center of the disc-shaped recording medium mounted on the disc table,
An optical pickup characterized in that the lens center of the first objective lens is positioned on a line segment passing through the lens center of the second objective lens and extending in the tangential direction. A first laser light source that emits a first laser beam;
A second laser light source that emits a second laser beam having a wavelength different from that of the first laser beam;
A first optical path for guiding the first laser light from the first laser light source to the first objective lens;
A second optical path for guiding the second laser light from the second laser light source to the second objective lens;
Optical path combining means for combining a part of the first and second optical paths;
The optical pickup according to claim 1, further comprising: an optical path separating unit that separates the combined optical path synthesized by the optical path synthesizing unit at a stage preceding the first and second objective lenses. The optical path combining means combines the first and second optical paths on an optical path before the first and second laser beams are introduced into the biaxial actuator. 2. The optical pickup according to 2. The optical path separation means has wavelength selectivity, and is synthesized by the optical path synthesis means by separating the first and second laser lights according to the wavelengths of the first and second laser lights. The optical pickup according to claim 2, wherein the optical path is separated. Each disk-shaped recording medium mounted on the disk table and having a different working wavelength includes a moving base moved in the radial direction of the disk-shaped recording medium mounted on the disk table and an objective lens driving device arranged on the moving base. Corresponding to the disk drive device configured to irradiate laser light of at least two types of wavelengths,
The objective lens driving device is:
A fixed block fixed to the moving base;
A recording track which is operated in a focusing direction which is a direction in which the fixed block is separated from and contacting the recording surface of the disk-shaped recording medium and a tracking direction which is a substantially radial direction of the disk-shaped recording medium and which is orthogonal to both the focusing direction and the tracking direction. Comprising a first objective lens and a movable block for holding the second objective lens, which are spaced apart in the tangential direction of
The first objective lens focuses the first laser beam on the recording surface of the disc-shaped recording medium,
The second objective lens has a second laser having a shorter wavelength than the first laser beam on a recording surface of a disc-shaped recording medium of a type different from the disc-shaped recording medium on which the first laser beam is condensed. Condensing light,
The lens center of the first objective lens or the second objective lens is positioned on a line segment extending in the radial direction of the disc-shaped recording medium through the center of the disc-shaped recording medium mounted on the disc table,
A disk drive device characterized in that the lens center of the first objective lens is positioned on a line segment passing through the lens center of the second objective lens and extending in the tangential direction. A first laser light source that emits a first laser beam;
A second laser light source for emitting the second laser light;
A first optical path for guiding the first laser light from the first laser light source to the first objective lens;
A second optical path for guiding the second laser light from the second laser light source to the second objective lens;
Optical path combining means for combining a part of the first and second optical paths;
6. The disk drive device according to claim 5, further comprising: an optical path separating unit that separates the combined optical path synthesized by the optical path synthesizing unit at a stage preceding the first and second objective lenses.

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