JP4785767B2 - Optical pickup device - Google Patents

Description

  The present invention relates to an optical pickup device corresponding to a plurality of optical discs having different wavelengths of corresponding laser beams, and in particular, corrects spherical aberration of laser beams irradiated on an optical disc by an aberration correction lens that can be driven and displaced in an optical axis direction. The present invention relates to an optical pickup device having the configuration described above.

  In an optical disc in which signal reproduction and / or signal recording is performed optically using a laser beam, recording is performed from a DVD (Digital Versatile Disk) using a laser beam (for example, 405 nm) in a blue-violet (blue) wavelength band of 400 nm to 420 nm. Optical disc standards with improved density, Blu-ray Disc (trademark) standard, and HD DVD (High Density Digital Versatile Disk) standard are known.

  The optical pickup device corresponding to the high-density optical disc standard that uses such blue-violet laser light to improve the recording density is required for ensuring the signal recording quality as the recording signal density increases. Is severe, and the influence of the spherical aberration of the laser beam focused on the signal layer through the transparent substrate of the optical disk is great, and the signal layer corresponds to a multilayer optical disk having two or more layers. Since the thickness of the transparent substrate is different, it is necessary to correct the spherical aberration. In order to correct this spherical aberration, it is known that the beam expander or collimator lens is driven in the optical axis direction according to the spherical aberration, and the beam expander or collimator lens is used as an aberration correction lens for correcting the spherical aberration. Yes.

  In particular, in the case of a Blu-ray Disc, the NA (numerical aperture) of the objective lens is 0.85, which is compared with other optical disc standards (for example, HD DVD NA 0.65, DVD NA 0.6, CD NA 0.45). Since the influence of the spherical aberration of the laser beam converged on the signal layer of the optical disk is extremely large and it is almost essential to correct this spherical aberration, in the case of an optical pickup device compatible with Blu-ray Disc, the spherical surface Some aberration correction means for correcting aberration is required, and an aberration correction lens is often used as the aberration correction means.

By the way, a lens driving device that drives the aberration correction lens in the optical axis direction supports a holding member that holds the aberration correction lens by a guide rail so that the aberration correction lens can be displaced in the optical axis direction of the aberration correction lens, and the stepping motor Further, it is driven using a drive source such as a voice coil motor or a piezoelectric element. (See Patent Documents 1 and 2)
By the way, the optical disk drive compatible with the high density optical disk standard using the blue-violet laser beam is also adapted to the conventional DVD standard and CD standard optical disks. For this reason, even in an optical pickup device that is compatible with the high-density optical disc standard, in addition to the high-density optical disc, the conventional DVD standard and CD standard are also supported. (See Patent Documents 3 and 4)
JP 2006-244646 A JP 2004-39068 A JP 2005-182941 A JP 2004-259414 A

In an optical pickup device compatible with high-density optical discs and conventional optical discs such as DVD and CD, the high-density optical disc optical path and the conventional optical disc optical path are divided into separate paths in order to obtain high-quality optical characteristics. Is advantageous in optical design. Therefore, there is a demand for an optical pickup device in which a high-density optical disk system optical path and a conventional standard optical disk system optical path are designed as separate paths. However, the optical pickup apparatus is limited in outer dimensions due to requirements on the optical disk drive side. When the aberration correction lens is disposed in the optical path for the high-density optical disk, there is a problem that it is difficult to secure a region in which the lens driving device for the aberration correction lens is disposed in the housing of the optical pickup device.

  By the way, the optical pickup device is generally configured by installing an objective lens driving device for driving an actuator movable portion having a lens holder on which an objective lens is mounted, in a housing in which various optical components are incorporated.

  In the objective lens driving device, magnets are arranged opposite to each other on both sides of the lens holder, and a pair of drive coils respectively opposed to these magnets are mounted on the lens holder so that the lens holder is sandwiched between the magnetic circuits. In many cases, the driving center acting on the lens holder is set at the center of the lens holder so that the actuator movable portion can be driven with good characteristics by suppressing unnecessary rotational movement.

  In an optical pickup device using such an objective lens driving device, when a rising mirror is arranged directly below the objective lens to reduce the thickness, the side where the magnetic circuit of the objective lens driving device is not formed Therefore, it is necessary to guide the laser beam to the rising mirror. For this reason, in the optical pickup device having such a configuration, the arrangement of the high-density optical disc optical path and the optical disc optical path of the conventional standard is further restricted, and each optical path is placed on the housing due to the restriction of the outer shape of the housing. It was difficult to provide.

In the invention according to claim 1, the direction of the first laser light emitted from the first laser light source and the direction of the second laser light emitted from the second laser light source are substantially orthogonal to the optical axis of the objective lens. The first and second laser light sources are set in a direction, a rising mirror is disposed immediately below the objective lens, and the first and second laser beams emitted from the first and second laser light sources are respectively A beam splitter that guides the first and second laser beams from the outer peripheral side of the optical disc to the rising mirror is disposed, and corresponds to the second laser light source and the second optical disc in the transmission optical path of the beam splitter. A second optical disc system optical path in which the optical element is arranged is formed, and an optical element corresponding to the first laser light source and the first optical disc is arranged in the reflected optical path of the beam splitter. Forming a first optical disk system optical path, the first optical disk system optical path disposed reflection mirror to bend at an obtuse angle toward the inner peripheral side of the optical disk in terms of avoiding the objective lens driving device of the optical axis of the first laser beam The optical path of the first laser beam is bent so as to bypass the objective lens driving device by the reflection mirror and the beam splitter, and the spherical aberration of the first laser beam irradiated to the first optical disc is corrected. Preferably, a collimator lens supported so as to be displaceable in the optical axis direction of the first laser beam is disposed in front of the reflecting mirror in the forward path of the first optical disc system optical path , and the collimator lens is guided by the guide rail to the optical axis. Held by a holding member supported so as to be displaceable in the direction, and the holding member is driven by a driving motor to be displaced in the optical axis direction. It is arranged on the opposite side of the objective lens driving device across the collimator lens. As a result, the optical path length of the first optical disc system is ensured, and the guide means for guiding the collimator lens along the optical path of the first optical disc system between the first laser light source and the reflecting mirror of the housing and the drive for driving the collimator lens in the optical axis direction An area for placing the source is secured in the housing. In addition, the collimator lens is arranged on the forward path of the first optical disk system optical path and in front of the reflective path.

According to the present invention, the optical path of the first optical disc system is bent so as to bypass the objective lens driving device by the reflection by the reflection mirror bent at an obtuse angle and the reflection by the beam splitter , and between the first laser light source and the reflection mirror in the housing. Since the collimator lens is disposed in the optical disc, the optical path length of the first optical disc system is ensured by an optical design in which the first optical disc system optical path and the second optical disc system optical path are divided into different paths, respectively. An optical pickup device having a configuration in which a collimator lens is disposed in the optical path can be provided.
In addition, since the collimator lens is disposed in front of the reflection mirror in the forward path of the first optical disc system optical path, the degree of freedom in optical design in the range from the collimator lens to the beam splitter is high, and the arrangement position of the reflection mirror High degree of freedom.

In addition, since the first and second laser beams are guided to the common optical path by the beam splitter and guided to the rising mirror from the outer peripheral side of the optical disk, the optical axis is bent by the rising mirror immediately below the objective lens, thereby reducing the thickness. In the optical pickup apparatus, the objective lens driving device is suitable when the magnetic circuit is configured symmetrically on both sides of the lens holder, and the first and second optical discs corresponding to the lens holder and the first optical disc, respectively. And the second objective lens is suitable for a configuration in which the second objective lens is arranged in the radial direction of the disc on the inner peripheral side and the outer peripheral side, respectively.

  FIG. 1 is a plan view of an optical arrangement showing an embodiment of an optical pickup device according to the present invention, and FIG. 2 is a partial end view taken along line A-A 'of FIG. This optical pickup device has a configuration corresponding to CD, DVD, and Blu-ray Disc (hereinafter abbreviated as BD). As shown in an exploded perspective view of FIG. 3 and an assembled perspective view of FIG. The apparatus 20 is configured by being installed in a housing 30 in which various optical components are incorporated.

  The objective lens driving device 20 includes a first objective lens 21 corresponding to BD and a second objective lens 22 corresponding to DVD and CD, respectively, in a radial direction (so-called tracking) in an optical disc (an optical disc in a state of being mounted on the turntable T). The actuator movable portion including the lens holder 23 mounted side by side on the inner and outer peripheral sides is driven.

  The first objective lens 21 is designed, for example, such that the NA (Numerical Aperture) for a laser beam having a BD compatible wavelength is 0.85.

  The second objective lens 22 is formed with an annular diffractive structure (not shown) centered on the optical axis on the incident surface, and diffracted light of a predetermined order is made transparent on each DVD or CD optical disk by the diffractive action of this diffractive structure. It is designed for two-wavelength design so that spherical aberration is appropriately corrected for the thickness of the substrate layer, and for example, the NA for a laser beam with a DVD-compatible wavelength is 0.65, and CD-compatible The NA for the laser beam having the wavelength is designed to be 0.51.

  The magnetic circuit of the objective lens driving device 20 is configured as shown in the plan view of FIG. 5 and the perspective view of FIG. Tracking coils 24 and 25 having winding axes in the tangential direction (tangential direction) of the signal track are respectively bonded to the side surfaces of the lens holder 23 in the direction orthogonal to the tracking direction, and the focus coils 26 and 27 are provided. Each is glued. The focus coil 26 is configured by connecting two coil bodies 26a and 26b having a winding axis in the focus direction in the tracking direction, and the focus coil 27 is two coil bodies 27a and 27b having a winding axis in the focus direction. Are connected in the tracking direction. And each magnet 28a, 28b, 28c and 29a, 29b which produces | generates an effective magnetic flux in the effective area | region of each drive coil (tracking coils 24 and 25 and focus coils 26 and 27) which acts effectively to drive an actuator movable part. 29c are arranged opposite to each other on both sides of the lens holder 23.

  The magnetic circuit of the objective lens driving device 20 configured as described above is configured so that each driving coil is arranged symmetrically with respect to an imaginary line (corresponding to AA ′ in FIG. 1) in the tracking direction passing through the center of gravity of the actuator movable portion. The position and the magnetic pole of the magnet are set. That is, the magnetic circuit is configured symmetrically on both sides of the lens holder 23, and the driving center acting on the actuator moving part in the plane orthogonal to the focus direction coincides with the center of gravity of the actuator moving part, so that the actuator is movable. Unnecessary rotational motion is suppressed and the motor is driven with good characteristics.

In this case, each magnet is magnetized as shown in FIG. 5, and the lens holder 23 is symmetrical with respect to an imaginary line in the tracking direction passing through the center of gravity of the actuator movable portion in consideration of the winding direction of each drive coil. A driving force in the same direction is generated on each side surface. Driving signals in opposite directions flow through the coil bodies 26a and 26b of the focus coil 26 mounted on one side surface of the lens holder 23. In addition, drive signals in opposite directions flow through the coil bodies 27a and 27b of the focus coil 27 mounted on the other side surface of the lens holder 23. As a result, a driving force in the focus direction is generated for each side surface of the lens holder 23. The driving force in the focus direction generated for each side surface of the lens holder 23 is set so as to be the same direction by the focus coils 26 and 27. Therefore, the actuator movable portion is driven in the focus direction in accordance with the focus drive current that flows through the focus coils 26 and 27 on each side surface of the lens holder 23.

  Further, in the focus coils 26 and 27, a drive signal in the same direction is sent to each coil body of the focus coils 26 and 27 for each side surface of the lens holder 23, so that each side surface of the lens holder 23 has a radial tilt direction. A driving force is generated, and a driving force in the same radial tilt direction is generated on each side surface of the lens holder 23. Therefore, the actuator movable portion is driven in the radial tilt direction in accordance with the radial tilt drive current that is supplied to the focus coils 26 and 27 on each side surface of the lens holder 23 while being superimposed on the focus drive current.

  In FIG. 1, a first laser unit 1 serving as a BD laser light source has a light emitting point 2 that emits a laser beam having a BD suitable wavelength in a blue-violet (blue) wavelength band of 400 nm to 420 nm suitable for BD, for example, 405 nm. Consists of.

  The second laser unit 3 serving as a DVD and CD laser light source has a DVD laser emission point 4 that emits a laser beam having a red wavelength band of 645 nm to 675 nm suitable for DVD, for example, 650 nm, on the same semiconductor substrate. It is composed of a laser diode having a CD compatible wavelength suitable for CD in a wavelength range of 765 nm to 805 nm, for example, a CD laser emission point 5 that emits a laser beam of 780 nm. This is a multi-laser unit that emits two-wavelength laser light suitable for recording and reproduction.

  The laser beam having a wavelength suitable for BD emitted from the light emitting point 2 of the first laser unit 1 is used by the diffraction grating 6 for tracking control of the differential push-pull method and focus control of the differential astigmatism method. After being diffracted to form folded light and formed into three beams, the polarization direction of linearly polarized light is adjusted by a half-wave plate 7 formed integrally with the diffraction grating 6 and supplied to the polarizing beam splitter 8.

  Since a polarizing film that reflects most of the laser light via the half-wave plate 7 is formed on the filter surface 8a of the polarizing beam splitter 8, most of the laser light supplied to the polarizing beam splitter 8 (for example, 95) % Or more) is reflected by the filter surface 8a and guided to the collimator lens 9, and a part (for example, less than 5%) passes through the filter surface 8a and is received by the front monitor diode 10.

  The front monitor diode 10 generates a monitor output based on the amount of received laser light, and the amount of laser light emitted by the first laser unit 1 is controlled to a predetermined amount by monitoring the monitor output. become.

  The laser light reflected by the filter surface 8a of the polarization beam splitter 8 and guided to the collimator lens 9 is made into parallel light by the collimator lens 9, and then the optical axis is bent by the reflection mirror 11 so that the quarter wavelength plate is obtained. 12, and is polarized into circularly polarized light by the ¼ wavelength plate 12 and guided to the beam splitter 13.

  The filter surface 13a of the beam splitter 13 is a dichroic filter and is provided with a reflection / transmission coating having wavelength selectivity. The filter surface 13a has a reflectivity that substantially totally reflects 405 nm laser light, and also has a transmittance that substantially totally transmits 650 nm and 780 nm laser light. As will be clearly described later, the beam splitter 13 plays a role of arranging the first laser unit 1 and the second laser unit 3 in separate optical paths.

  Therefore, the laser beam having the BD compatible wavelength is reflected by the filter surface 13a of the beam splitter 13, the optical axis is bent, and the laser beam is guided from the notch portion on the side surface in the tracking direction of the lens holder 23 to the space inside the lens holder 23. .

  Here, in the space inside the lens holder 23, as shown in the partial end view of FIG. 2, the first objective lens 21 and the second objective lens 22 are installed in the housing 30 at substantially the same height immediately below each other. A first raising mirror 14 and a second raising mirror 15 are arranged.

  The installation portions 30a and 30b for installing the second rising mirror 15 of the housing 30 are formed by two substantially triangular tongues protruding at positions corresponding to both sides of the back surface of the second raising mirror 15, respectively. An optical path of laser light that passes through the second rising mirror 15 is secured between the portion 30a and the installation portion 30b.

  The second rising mirror 15 is formed by forming a dichroic filter on the surface of a flat glass plate, and this dichroic filter transmits almost 405 nm laser light opposite to the filter surface 13 a of the beam splitter 13. In addition to having a good transmittance, the laser beam has such a characteristic that it substantially totally reflects 650 nm and 780 nm laser beams.

  Therefore, the laser beam having the BD compatible wavelength reflected by the filter surface 13 a of the beam splitter 13 and guided to the space inside the lens holder 23 is transmitted through the second raising mirror 15 and reaches the first raising mirror 14. . Note that the laser light having the DVD compatible wavelength and the CD compatible wavelength is substantially totally reflected by the second raising mirror 15.

  The laser beam having the BD compatible wavelength that has reached the first rising mirror 14 is reflected by the first rising mirror 14, bent, and incident on the first objective lens 21. The first objective lens 21 is controlled in the focus direction, the tracking direction, and the radial tilt direction by driving the lens holder 23 by the objective lens driving device 20, and the laser light is NA0 adapted to BD by the first objective lens 21. .85 and condensed onto the signal layer of the BD.

The laser light modulated and reflected by the signal layer of the BD returns to the first objective lens 21, travels in the reverse direction along the optical path when traveling toward the BD, and returns to the beam splitter 13. Since the laser beam returned to the beam splitter 13 has a BD compatible wavelength, it is substantially totally reflected by the beam splitter 13, returns through the same optical path as the forward path, and passes through the quarter wavelength plate 12. Since the laser beam having a wavelength suitable for BD passes through the quarter-wave plate 12 twice in the forward path and the backward path, the linear polarization direction is rotated by 90 degrees in the forward path and the backward path, and in the forward path to the BD. Laser light that was s-polarized light becomes p-polarized light. The p-polarized laser light reaches the polarization beam splitter 8 via the reflection mirror 11 and the collimator lens 9. Since the filter surface 8 a of the polarization beam splitter 8 has a film characteristic that almost all transparent to the laser beam of p-polarized light, the laser beam returned to the polarization beam splitter 8 is transmitted through the polarization beam splitter 8, The anamorphic lens 16 gives astigmatism as a focus error component indicating a focal shift of the laser beam with respect to the signal layer of the BD, and the focal length is adjusted and led to the BD photodetector 17.

  The BD photodetector 17 receives a light receiving spot including a focus error component, a tracking error component, and a radial tilt error component.

  Therefore, by calculating each light receiving output obtained from each light receiving segment constituting the light receiving unit of the BD photodetector 17 based on predetermined arithmetic expressions for obtaining various signals, a BD information data signal, a focus error signal, A tracking error signal and a radial tilt error signal are obtained.

  The first objective lens 21 is driven by the objective lens driving device 20 in accordance with a focus error signal, a tracking error signal, and a radial tilt error signal, and is subjected to focus control, tracking control, and radial tilt control.

  As described above, the laser beam having the BD compatible wavelength emitted from the first laser unit 1 reaches the BD, and the laser beam having the BD compatible wavelength reflected and returned by the BD reaches the BD photodetector 17. The optical path becomes a BD optical path.

  On the other hand, a laser beam having a wavelength suitable for DVD emitted from the light emitting point 4 for the DVD laser of the second laser unit 3 or a laser beam having a wavelength suitable for CD emitted from the light emitting point 5 for the CD laser, After being diffracted into three beams by a diffraction grating 31 corresponding to two wavelengths of wavelengths to form ± first-order diffracted light used for tracking control of the differential push-pull method and focus control of the differential astigmatism method The polarization direction of the linearly polarized light is adjusted by the half-wave plate 32 formed integrally with the diffraction grating 31 and supplied to the polarization beam splitter 33.

  A polarizing film that transmits most of the laser light having the DVD compatible wavelength and the CD compatible wavelength through the half-wave plate 32 is formed on the filter surface 33 a of the polarizing beam splitter 33, and is thus supplied to the polarizing beam splitter 33. Most of the laser light (for example, 95% or more) passes through the filter surface 33a and is guided to the quarter-wave plate 34 bonded to the output surface of the polarization beam splitter 33, and a part (for example, less than 5%) is filtered. The light is reflected by the surface 33 a and received by the front monitor diode 35.

  The front monitor diode 35 generates a monitor output based on the amount of received light of each of the laser light having the DVD compatible wavelength and the CD compatible wavelength received, and each of the DVD compatible wavelength and the CD compatible wavelength emitted by the second laser unit 3. The amount of light is controlled to a predetermined amount by monitoring the monitor output.

  The laser light transmitted through the filter surface 33a of the polarization beam splitter 33 and guided to the quarter-wave plate 34 is polarized into circularly polarized light by the quarter-wave plate 34, and then the optical path is made substantially perpendicular by the reflection mirror 36. The light is bent and converted into parallel light by the collimator lens 37 and guided to the beam splitter 13. The laser beam having the wavelength suitable for DVD or the laser beam having the wavelength suitable for CD guided to the beam splitter 13 is almost totally transmitted due to the wavelength selectivity of the filter surface 13a of the beam splitter 13 regardless of the laser beam having any wavelength. The laser beam that has passed through the filter surface 13a of the beam splitter 13 is guided to a space inside the lens holder 23 from a notch portion on the side surface in the tracking direction of the lens holder 23, and a second rising mirror disposed in the space. Due to the 15 dichroic filter characteristics, either the laser beam having the wavelength suitable for DVD or the laser beam having the wavelength for CD is substantially totally reflected by the second raising mirror 15. For this reason, the laser beam having the DVD compatible wavelength or the CD compatible wavelength is reflected by the second raising mirror 15, bent, and incident on the second objective lens 22.

  When a laser beam having a wavelength suitable for DVD is incident, the second objective lens 22 is controlled in the focus direction, the tracking direction, and the radial tilt direction by driving the lens holder 23 by the objective lens driving device 20, respectively. Is condensed by the second objective lens 22 so that spherical aberration is corrected by NA 0.65 suitable for DVD, and is irradiated onto the signal layer of the DVD.

  When a laser beam having a wavelength suitable for CD is incident, the second objective lens 22 is controlled in the focus direction and the tracking direction by driving the lens holder 23 by the objective lens driving device 20, and the laser beam is the second objective lens. The light is condensed by the lens 22 so that the spherical aberration is corrected by NA 0.51 suitable for the CD, and is irradiated onto the signal layer of the CD.

  The laser beam modulated and reflected by the signal layer of the DVD or CD optical disk returns to the second objective lens 22, travels in the reverse direction along the optical path when traveling to the optical disk, and returns to the beam splitter 13. Since the laser beam returned to the beam splitter 13 has a wavelength suitable for DVD or CD, the laser beam is almost completely transmitted by the beam splitter 13, and returns to the same path as the forward path through the collimator lens 37 and the reflection mirror 36. It passes through the wave plate 34 and passes through the quarter wave plate 34 twice in the forward path and the return path. Therefore, the laser beam in the return path is rotated by 90 degrees in the direction of linear polarization with the laser beam in the outbound path, and the laser beam that has been p-polarized in the outbound path to the optical disk becomes s-polarized light and reaches the polarization beam splitter 33. Since the filter surface 33a of the polarization beam splitter 33 has a film characteristic that almost totally reflects the s-polarized laser beam, the laser beam returned to the polarization beam splitter 33 is reflected by the filter surface 33a and is cylindrical. After astigmatism serving as a focus error component indicating the focal shift of the laser beam with respect to the signal layer of the optical disk is given by the lens 38, it is guided to a photodetector 39 for both DVD and CD.

  The photodetector 39 is formed with a DVD light-receiving unit that receives a laser beam having a DVD-compatible wavelength and a CD light-receiving unit that receives a laser beam having a CD-compatible wavelength. A spot for receiving a laser beam having a wavelength suitable for a DVD including a focus error component, a tracking error component, and a radial tilt error component in a segment is received, and a focus error component and a tracking error component are received in each light receiving segment constituting the light receiving unit for CD. The light receiving spot of the laser beam having the CD compatible wavelength including the light is received.

  Therefore, a DVD information data signal, a focus error signal, by calculating each light receiving output obtained from each light receiving segment constituting the DVD light receiving portion of the photodetector 39 based on predetermined arithmetic expressions for obtaining various signals. A tracking error signal and a radial tilt error signal are obtained.

  That is, when DVD recording or reproduction is performed, the second objective lens 22 is driven by the objective lens driving device 20 in accordance with the focus error signal, the tracking error signal, and the radial tilt error signal, and the focus control, tracking control, and radial control are performed. Tilt control is performed.

  Further, by calculating each light receiving output obtained from each light receiving segment constituting the light receiving section for CD of the photodetector 39 based on a predetermined arithmetic expression for obtaining various signals, the information data signal of the CD, the focus error signal, and the tracking An error signal is obtained.

  That is, when a CD is recorded or reproduced, the second objective lens 22 is driven by the objective lens driving device 20 according to the focus error signal and the tracking error signal, and is subjected to focus control and tracking control.

  As described above, the laser light with the DVD compatible wavelength and the laser light with the CD compatible wavelength emitted from the second laser unit 3 reach the optical disc, and the laser light reflected and returned by the optical disc reaches the photodetector 39. Are the DVD and CD optical paths.

  The optical pickup device shown in FIG. 1 is configured as described above and is compatible with CD, DVD and Blu-ray Disc, and corresponds to the second laser unit 3 and DVD and CD optical discs in the transmission optical path of the beam splitter 13. DVD and CD system optical paths (optical axes are indicated by two-dot chain lines in FIG. 1) in which optical elements are arranged are formed, and optical elements corresponding to the first laser unit 1 and the BD are arranged in the reflected optical path of the beam splitter 13. A BD optical path (indicated by an alternate long and short dash line in FIG. 1) is formed.

  The beam splitter 13 guides a laser beam having a BD compatible wavelength from the outer peripheral side of the optical disc to the first rising mirror 14 and guides a laser beam having a DVD compatible wavelength and a laser beam having a CD compatible wavelength to the second rising mirror 15. Thus, it is arranged outside the objective lens driving device 20.

  The BD optical path is bent so as to bypass the objective lens driving device 20 by the beam splitter 13 and the reflection mirror 11, and the collimator lens 9 is disposed in front of the optical path from the reflection mirror 11 in the forward path. Since the laser light on the optical path ahead of the collimator lens 9 in the forward path of the BD optical path is parallel light until it enters the first objective lens 21, the optical range of the collimator lens 9 to the beam splitter 13 in the BD optical path is optical. The degree of freedom in design is high, and the degree of freedom in the arrangement position of the reflection mirror 11 is high.

  The first laser unit 1, the polarization beam splitter 8, and the light detection for BD are arranged on the optical path before the collimator lens 9 on the forward path of the BD system optical path and on the optical path ahead of the collimator lens 9 on the return path. The optical elements such as the container 17 are arranged on a protruding portion 30 a that protrudes along the outer periphery of the turntable T of the housing 30, and the optical elements are efficiently arranged without waste according to the shape of the housing 30. .

  The collimator lens 9 is held by a holding member 41, and this holding member 41 is supported by a main guide rail 42 and a sub guide rail 43 fixed to the housing 30 so as to be displaceable in the optical axis direction. A feed member 46 that is screwed into a feed screw 45 that is rotated by a drive motor 44 is connected to the holding member 41. Therefore, when the feed screw 45 is rotated by the drive motor 44, the feed member 46 is driven in the axial direction of the feed screw 45, and the holding member 41 is slid along the guide rails 42 and 43 along with this, and the collimator lens 9. Are driven in the optical axis direction.

  In this way, the collimator lens 9 is displaced in the optical axis direction, and the spherical aberration of the laser beam converged on the signal layer through the BD transparent substrate is corrected.

  Incidentally, as described above, the BD optical path is bent by the beam splitter 13 and the reflection mirror 11 so as to bypass the objective lens driving device 20, and the collimator lens 9 is disposed in front of the optical path from the reflection mirror 11 in the forward path. In addition, the BD optical path is bent by the reflecting mirror 11 to an obtuse angle that is + 10 ° to + 30 ° higher than a right angle (90 °), for example, 110 °. Therefore, the first laser unit 1 and the second laser unit 3 are disposed on the opposite side of the collimator lens 9 of the housing 30 from the objective lens driving device 20 with the region where the driving motor 44, the feed screw 45, and the main guide rail 42 are disposed. Secured in between. A region for arranging the sub guide rail 43 is secured between the collimator lens 9 of the housing 30 and the objective lens driving device 20.

  The DVD and CD optical paths have their optical axes bent in substantially the same direction as the direction in which the beam splitter 13 bends the BD optical path by the reflecting mirror 36, and the second laser unit 3 in the DVD and CD optical paths to the reflecting mirror 36. Is substantially parallel to the optical path from the reflecting mirror 11 to the beam splitter 13 of the BD optical path, so that the DVD and CD optical paths do not extend to the outer peripheral side of the optical disc, and can be used in accordance with the shape of the housing 30. Arranged efficiently.

1 is an optical layout diagram showing an embodiment of an optical pickup device according to the present invention. FIG. 2 is a partial end view taken along A-A ′ in FIG. 1. It is a disassembled perspective view of the optical pick-up apparatus shown in FIG. FIG. 2 is an assembled perspective view of the optical pickup device shown in FIG. 1. 3 is a plan view showing a configuration of a magnetic circuit of the objective lens driving device 20. FIG. 3 is a perspective view showing a configuration of a magnetic circuit of the objective lens driving device 20. FIG.

Explanation of symbols

20 Objective lens driving device 30 Housing 21 First objective lens 22 Second objective lens 23 Lens holder 24, 25 Tracking coil 26, 27 Tracking coil 28a, 28b, 28c, 29a, 29b, 29c Magnet 1 First laser unit 3 Second Laser unit 9 Collimator lens (Aberration correction lens)
DESCRIPTION OF SYMBOLS 11 Reflection mirror 13 Beam splitter 14 1st raising mirror 15 2nd raising mirror 17 Photodetector 36 for BD Reflection mirror 39 Photodetector 41 shared by DVD and CD Holding member 42, 43 Guide rail 44 Driving motor

Claims (4)

An actuator movable portion including first and second laser light sources for generating first and second laser beams corresponding to different types of first and second optical discs, and a lens holder on which an objective lens is mounted; In an optical pickup device in which an objective lens driving device to be driven is installed in a housing in which various optical components are incorporated, the direction of the first laser light emitted from the first laser light source and the second emitted from the second laser light source The first and second laser light sources are installed such that the direction of the laser beam is set in a direction substantially orthogonal to the optical axis of the objective lens, a rising mirror is disposed directly below the objective lens, and the first The first and second laser beams respectively emitted from the second laser light source and the second laser light source are guided to a common optical path, and first from the outer peripheral side of the optical disc. And a beam splitter for guiding the second laser beam to the rising mirror, and a second optical disk system optical path in which an optical element corresponding to the second laser light source and the second optical disk is disposed in the transmission optical path of the beam splitter. A first optical disk system optical path in which an optical element corresponding to the first laser light source and the first optical disk is disposed is formed in the reflected optical path of the beam splitter, and the optical axis of the first laser beam is formed in the first optical disk system optical path. A reflection mirror that avoids the objective lens driving device and bends at an obtuse angle in the direction toward the inner peripheral side of the optical disk is disposed, and the first laser beam is configured to bypass the objective lens driving device by the reflection mirror and the beam splitter. And the optical path of the first laser beam is corrected in order to correct the spherical aberration of the first laser beam applied to the first optical disc. Holding position rotatably supported by collimator lens is disposed on an optical path front of the reflecting mirror in the forward path of the first optical disk system optical path, and said collimator lens is displaceably supported in the optical axis direction by the guide rails It is held by a member, the holding member is driven by a driving motor and displaced in the optical axis direction, and the driving motor is disposed on the opposite side of the objective lens driving device with the collimator lens interposed therebetween. Optical pickup device. 2. The reflection mirror for bending the optical axis of the second laser light in a direction substantially the same as the direction in which the beam splitter bends the first optical disk system optical path is disposed in the second optical disk system optical path. Optical pickup device. The lens holder has first and second objective lenses corresponding to the first and second optical discs arranged side by side in the radial direction of the disc on the inner and outer peripheral sides, respectively, directly below the first and second objective lenses. The first and second rising mirrors are arranged at substantially the same height, and the outer periphery of the optical disk is formed by a beam splitter that guides the first and second laser beams respectively emitted from the first and second laser light sources to a common optical path. The second laser beam is guided from the side to the second rising mirror, and the first laser beam is transmitted through the second rising mirror and guided to the first rising mirror, and the second laser beam is guided to the second rising mirror. 2. The laser beam according to claim 1, wherein the first laser beam is reflected by the mirror and guided to the second objective lens, and the first laser beam is reflected by the first rising mirror and guided to the first objective lens. Pickup device. 2. The optical pickup device according to claim 1, wherein the objective lens driving device has magnetic circuits symmetrically arranged on both sides of the lens holder.

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