JP4193868B2 - Optical pickup and disc player - Google Patents

Description

  The present invention relates to an optical pickup for writing and reading information signals to and from a disk-shaped optical recording medium such as an optical disk and a magneto-optical disk, and a disk player using the optical pickup.

  Conventionally, a disk-shaped optical recording medium such as an optical disk or a magneto-optical disk has been proposed as an information signal recording medium, and an optical pickup for writing and reading information signals on such a disk-shaped optical recording medium has been proposed. Furthermore, a disc player using this optical pickup has been proposed.

  Such a disk-shaped optical recording medium has a transparent substrate made of a transparent material such as polycarbonate, and a signal recording layer deposited on one main surface of the transparent substrate. The optical pickup includes a semiconductor laser serving as a light source, an objective lens into which a light beam emitted from the semiconductor laser is incident, and a photodetector.

  The light beam incident on the objective lens is condensed and irradiated on the signal recording surface of the disk-shaped optical recording medium by the objective lens. At this time, this light beam is applied to the disk-shaped optical recording medium from the transparent substrate side of the disk-shaped optical recording medium, passes through the transparent substrate, and is collected on the signal recording surface of the signal recording layer. This objective lens is supported by a biaxial actuator and is moved and operated, so that the light beam is always focused on a location where an information signal is recorded on the signal recording surface, that is, on a recording track. This recording track is formed in a spiral shape on the main surface of the disc-shaped optical recording medium.

  In the disk-shaped optical recording medium, the light beam that has passed through the objective lens is condensed and irradiated, whereby the information signal is written or read at the portion irradiated with the light beam.

  The light beam irradiated on the signal recording surface is reflected by the signal recording surface after the light amount or the polarization direction is modulated in accordance with the information signal recorded on the signal recording surface, and returns to the objective lens.

  The reflected light beam reflected by the signal recording surface is received by the photodetector through the objective lens. This photodetector is a light receiving element such as a photodiode, and receives the reflected light beam that has passed through the objective lens and converts it into an electrical signal. Based on the electrical signal output from the photodetector, the information signal recorded on the disc-shaped optical recording medium is reproduced.

  Also, based on the electrical signal output from the photodetector, a focus error signal indicating the distance in the optical axis direction of the objective lens between the focal point of the light beam by the objective lens and the signal recording surface, and the focal point and the signal recording surface A tracking error signal indicating the radial distance of the disc-shaped optical recording medium from the upper recording track is generated. The biaxial actuator is controlled based on the focus error signal and the tracking error signal, and moves the objective lens so that each error signal converges to zero.

  By the way, in such a disk-shaped optical recording medium, the recording density of information signals has been increased to be used as an auxiliary storage device for computers and as a recording medium for audio and image signals.

  In order to write and read information signals to and from a disc-shaped optical recording medium with a high recording density in this way, the objective lens has a larger numerical aperture (NA) and the emission wavelength of the light source. Therefore, it is necessary to reduce the beam spot formed by focusing the light beam on the disk-shaped optical recording medium.

  However, when the numerical aperture of the objective lens is increased, the tilt of the disk-shaped optical recording medium, the uneven thickness of the transparent substrate of the disk-shaped optical recording medium, and the defocus (focal shift) of the light beam on the disk-shaped optical recording medium As a result, it becomes difficult to write and read information signals with respect to the disk-shaped optical recording medium.

  For example, when an inclination (skew) with respect to the optical axis of the objective lens of the disc-shaped optical recording medium occurs, wavefront aberration occurs in the light beam condensed on the signal recording surface, and an electric signal (RF output) output from the photodetector is generated. There will be an impact.

  This wavefront aberration is dominated by the third-order coma aberration generated in proportion to the cube of the numerical aperture of the objective lens and the tilt angle (skew angle) of the disk-shaped optical recording medium. Therefore, the allowable value for the tilt of the disk-shaped optical recording medium is inversely proportional to the cube of the numerical aperture of the objective lens, that is, the larger the numerical aperture, the smaller the allowable value.

  In an optical disc (such as a so-called compact disc) that is formed of a transparent substrate formed of a disc-shaped polycarbonate having a thickness of 1.2 mm and a diameter of 80 mm or 120 mm, and is generally used at present, ± 0 An inclination of .5 ° to ± 1 ° may occur.

  When the numerical aperture (NA) of the objective lens is increased in such an optical disc, the above-described wavefront aberration occurs in the light beam irradiated to the optical disc, the beam spot on the optical disc becomes asymmetrical, and the intersymbol interference is remarkably increased. As a result, accurate signal reproduction becomes difficult.

  The amount of such third-order coma aberration is proportional to the thickness of the transparent substrate of the optical disc. Therefore, the third-order coma aberration can be halved by reducing the thickness of the transparent substrate (for example, 0.6 mm). When the coma aberration is reduced in this way, an optical disc having a transparent substrate thickness of 1.2 mm and a transparent substrate thickness of 0.6 mm are used in combination. It will be.

By the way, when a plane parallel plate having a thickness t is inserted into the optical path of the convergent light beam collected by the objective lens, t × (NA) in relation to the thickness t and the numerical aperture NA of the objective lens. Spherical aberration proportional to ⁴ occurs.

  The objective lens is designed so that this spherical aberration is corrected. That is, since the amount of spherical aberration that occurs is different when the thickness of the transparent substrate is different, it is designed to be adapted to a predetermined thickness of the transparent substrate.

  For example, by using an objective lens designed to be adapted to an optical disk having a transparent substrate having a thickness of 0.6 mm, an optical disk having a transparent substrate having a thickness of 1.2 mm (for example, a compact disk, a write-once optical disk, a magneto-optical disk) When recording and reproducing information signals with respect to a disk), the difference in thickness (0.6 mm) of these transparent substrates is the tolerance of the error in the thickness of the transparent substrate that the optical pickup can handle. Is greatly exceeded. In this case, the objective lens cannot correct spherical aberration generated due to the difference in thickness of the transparent substrate, and good information signal recording and reproduction cannot be performed.

  Therefore, as disclosed in Japanese Patent Application No. 7-354198, an optical pickup having two objective lenses has been proposed. As shown in FIG. 27, this optical pickup is configured by attaching a first objective lens 105 and a second objective lens 106 on one lens bobbin 104 of a biaxial actuator 103. In this optical pickup, the light beam emitted from the light source 107 is incident on one of the first and second objective lenses 105 and 106 via the collimator lens 111 and the mirror 112. The first and second objective lenses 105 and 106 have different numerical apertures. The biaxial actuator 103 is disposed on an optical system block 108 containing the light source 107.

  In a disc player equipped with this optical pickup, the first type optical disc 101 with a transparent substrate thickness of, for example, 0.6 mm or the second type optical disc 102 with a thickness of, for example, 1.2 mm, has a central portion. Is held by a disk table attached to a drive shaft of a spindle motor (not shown) and rotated. The optical pickup is supported by the guide shaft 109 so as to be movable in the axial direction of the guide shaft 109 as indicated by an arrow S in FIG. This optical pickup is moved in the radial direction of the optical disks 101 and 102 held on the disk table.

  In this optical pickup, when the first type optical disc 101 is mounted on the disc table, the light source 107 is turned on and information signals are written to the first type optical disc 101 via the first objective lens 105. When reading is performed and the second type optical disk 102 is mounted on the disk table, the light source 107 is turned on and information signals are written to the second type optical disk 102 via the second objective lens 106. Read. Switching between the first and second objective lenses 105 and 106 on the optical path of the light beam from the light source 107 is performed by rotating the lens bobbin 104 around a support shaft 110 that supports the lens bobbin 104.

  Then, the lens bobbin 104 of the biaxial actuator 103 is rotated around the support shaft 110, so that the objective lenses 105 and 106 are moved to the axis of the guide shaft 109 as shown by an arrow T in FIG. The objective lens 105, 106 is made to follow the recording track on the optical disc 101, 102 by moving in the tracking direction which is substantially parallel to the direction.

  However, a write-once optical disc (so-called “CD-R”) having a transparent substrate with a thickness of 1.2 mm has a high wavelength dependency when reading an information signal, so that the recording density of the information signal is increased. In addition, information signals cannot be read using a light source with a light emission wavelength shortened. That is, the so-called “CD-R” signal recording layer is formed of an organic dye-based material, and absorbs a light beam having a shorter wavelength, for example, a light beam having a wavelength of 635 nm to 650 nm, thereby increasing the reflectance. As a result, the information signal cannot be read out by such a light beam having a shorter wavelength.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and two pieces of information signals can be satisfactorily written to and read from a disk-shaped optical recording medium having different transparent substrate thicknesses. An optical pickup having an objective lens, which can detect a good information signal even when any objective lens is used, and has a high wavelength dependency at the time of reading an information signal. An object of the present invention is to provide an optical pickup that can be used.

  The present invention also uses a disk-shaped optical recording medium that can record and reproduce information signals on and from a disk-shaped optical recording medium having different transparent substrate thicknesses and that has a high wavelength dependency when reading the information signal. An object of the present invention is to provide a disc player that can be used.

In order to solve the above-described problems, the optical pickup according to the present invention corresponds to a plurality of types of disc-shaped optical recording media which are provided on the light incident surface side and have different light-transmitting substrate thicknesses. The first and second objective lenses are mounted in a state where the optical axes of these objective lenses are parallel to each other. The focus direction is parallel to the optical axis of each objective lens, and the tracking direction is orthogonal to the optical axis of each objective lens. A movable portion that is moved to the fixed portion, a fixed portion that is disposed in a plane perpendicular to the optical axis of the movable portion, and a proximal end side that is attached to the fixed portion and a distal end side that is attached to the movable portion. the movable portion and a plurality of elastic support members for movably supporting the above focusing direction and the tracking direction, each of said objective by moving operating the movable portion A biaxial actuator for moving the lens in the focusing direction and the tracking direction, a first light source in which a light beam is incident via the first optical path with respect to the first objective lens with respect to the second objective lens And a second light source for making the light beam incident through the second optical path, and the light beam emitted from the first light source is substantially applied to the signal recording layer of the disk-shaped optical recording medium by the first objective lens. The light beam emitted from the second light source is condensed perpendicularly to the signal recording layer of the disk-shaped optical recording medium by the second objective lens. In an optical pickup that writes or reads an information signal to or from the disc-shaped optical recording medium by irradiating and condensing on the signal recording layer, the first light source The emission wavelength of the second light source is different from that of the second light source, the numerical aperture of the first objective lens is larger than the numerical aperture of the second objective lens, and the optical system block that supports the biaxial actuator is disc-shaped. When moving relative to the central portion of the optical recording medium, the objective lens of any one of the first and second objective lenses passes through the center of the disk-shaped optical recording medium. The system block and the disk-shaped optical recording medium move while facing each other with respect to a straight line parallel to the relative movement direction, and the other objective lens is perpendicular to the relative movement direction with respect to the one objective lens. Using one objective lens that moves in a state arranged in a direction and moves in a state of being opposed to a straight line passing through the center of the disk-shaped optical recording medium and parallel to the relative movement direction. Detecting tracking error when writing or reading an information signal to or from the disk-shaped optical recording medium corresponding to the one objective lens is performed by the three-beam method, and using the other objective lens, the other objective lens is used. The tracking error detection when the information signal is written to or read from the disk-shaped optical recording medium corresponding to the objective lens is different from the tracking error detection method when the one objective lens is used. It is characterized by performing.

In the optical pickup according to the present invention, the first and second objective lenses supported on the same movable part by the biaxial actuator are incident on the light beams emitted from the first and second light sources correspondingly. The light beam is irradiated substantially perpendicularly to the signal recording layer of the disk-shaped optical recording medium and condensed on the signal recording layer, and the information signal is written to or read from the disk-shaped optical recording medium. I do.
The present invention also provides an optical pickup capable of satisfactorily recording and reproducing information signals even on disc-shaped optical recording media having different operating wavelengths without incurring a complicated and large-sized apparatus configuration. Can be provided.
The present invention is characterized in that in each of the optical pickups described above, the emission wavelength of the first light source is 635 nm to 650 nm, and the emission wavelength of the second light source is 780 nm.
In the above-described optical pickup, the present invention is characterized in that the numerical aperture of the first objective lens is 0.6 and the numerical aperture of the second objective lens is 0.45 or less. .
Further , according to the present invention, the movable portion of the biaxial actuator is moved and operated by supplying the drive current to the drive coil by positioning the drive coil in the magnetic field formed by the drive circuit to which the drive coil is attached. It is characterized by that.
The disc player according to the present invention includes a plurality of types of discs that are provided on the light incident surface side and have a transparent substrate having a light transmission property and a signal recording layer, and the transparent substrates have different thicknesses. a recording medium holding mechanism for holding the Jo optical recording medium, the first and second objective lenses respectively corresponding to the disk-shaped optical recording medium of the plurality of types having different respective thicknesses of the transparent substrate is light of the objective lens A movable part mounted with its axes parallel to each other and moved in a focusing direction parallel to the optical axis of each objective lens and a tracking direction orthogonal to the optical axis of each objective lens, and the optical axis of the movable part A fixed part disposed at an interval in an orthogonal plane, a base end side is attached to the fixed part, a distal end side is attached to the movable part, and the movable part is attached to the focusing method. And a plurality of elastic support members for movably supporting on the tracking direction, and a biaxial actuator for moving the respective objective lens in the focusing direction and the tracking direction by moving operating the movable part, the A first light source that causes a light beam to be incident on the first objective lens via a first optical path; and a second light source that causes the light beam to be incident on the second objective lens via a second optical path. The light beam emitted from the first light source is irradiated by the first objective lens substantially perpendicularly to the signal recording layer of the disk-shaped optical recording medium and condensed on the signal recording layer, or The light beam emitted from the second light source is irradiated by the second objective lens substantially perpendicularly to the signal recording layer of the disc-shaped optical recording medium to be condensed on the signal recording layer. In the disc player that writes or reads information signals to or from the disc-shaped optical recording medium, the first light source and the second light source have different emission wavelengths, and the numerical aperture of the first objective lens Is larger than the numerical aperture of the second objective lens, and when the optical system block supporting the biaxial actuator is operated to move relative to the central portion of the disk-shaped optical recording medium, the first One of the first and second objective lenses is opposed to a straight line that passes through the center of the disk-shaped optical recording medium and is parallel to the relative movement direction of the optical system block and the disk-shaped optical recording medium. The other objective lens moves in a state where it is arranged in a direction perpendicular to the relative movement direction with respect to the one objective lens, Using one objective lens that moves through the center of the disk-shaped optical recording medium and faces the straight line parallel to the relative movement direction, the disk-shaped optical recording medium corresponding to the one objective lens is used. The tracking error at the time of writing or reading the information signal is detected by the three-beam method, and the information signal is sent to the disc-shaped optical recording medium corresponding to the other objective lens by using the other objective lens. The tracking error when writing or reading is performed by a method different from the tracking error detection method when the one objective lens is used.

  In the disc player according to the present invention, an optical system that supports the biaxial actuator and is capable of relative movement with respect to the disc-shaped optical recording medium in a direction in contact with and away from the center of the disc-shaped optical recording medium. A first objective lens passes through the center of the disk-shaped optical recording medium when the optical system block is moved and moved relative to the central portion of the disk-shaped optical recording medium. Diffraction that splits a light beam incident on the first optical path into zero-order light and at least ± first-order light that is moved in a state of being opposed to a straight line parallel to the relative movement direction of the disk and the disk-shaped optical recording medium An element is provided, and the condensing point of the zero-order light by the first objective lens and the disc based on the light amount difference of the reflected light beam from the disc-shaped optical recording medium of the ± primary light and the disc A tracking error signal indicating an amount of deviation in the radial direction of the disk-shaped optical recording medium from a recording track on the rectangular optical recording medium is obtained.

  In the disc player according to the present invention, the emission wavelength of the first light source is 635 nm to 650 nm, and the emission wavelength of the second light source is 780 nm. In the disc player, the numerical aperture of the first objective lens is 0.6, and the numerical aperture of the second objective lens is 0.45 or less.

  According to the present invention, it is possible to accurately write and read information signals by performing accurate tracking control on optical recording media having different thicknesses.

  Hereinafter, the best mode for carrying out the present invention will be described in the following order with reference to the drawings.

[1] Types of disc-shaped optical recording media [2] Outline of configuration of optical pickup [3] Configuration of biaxial actuator [4] Configuration of optical system block [5] Configuration of disc player [6] Configuration of biaxial actuator Other forms (1)
[7] Other forms of the configuration of the biaxial actuator (2)
[8] Other forms of the configuration of the biaxial actuator (3)
[1] Types of disc-shaped optical recording medium An embodiment for carrying out the invention shown here is an optical pickup and disc player according to the present invention having a transparent substrate thickness of 0.6 mm as shown in FIG. Laser beam irradiation is performed on both the first type optical disc 101 which is a disc-shaped optical recording medium and the second type optical disc 102 which is a disc-shaped optical recording medium having a transparent substrate 102a thickness of 1.2 mm. Thus, the apparatus is configured as an apparatus for writing and reading information signals.

  The first type optical disc 101 has a transparent substrate formed of a disc-shaped polycarbonate having a thickness of 0.6 mm and a diameter of 120 mm, and a signal recording layer formed on one main surface portion of the transparent substrate. It is configured. The first type optical disc 101 is composed of a disc body having a thickness of 1.2 mm, that is, a double-sided optical disc, in which two first type optical discs 101a and 101b are bonded to each other on the signal recording layer side. Yes.

  This first type of optical disk 101 writes and reads information signals by means of a laser beam having a first wavelength of 635 nm (or 650 nm) through an objective lens having a numerical aperture (NA) of 0.6. It is configured to be made. In the signal recording layer, the information signal is recorded along a recording track formed in a spiral shape.

  For example, a so-called “digital video disc (DVD)” has been proposed as one corresponding to the first type of optical disc 101.

  The second type optical disc 102 includes a transparent substrate 102a formed of a disc-shaped polycarbonate having a thickness of 1.2 mm and a diameter of 80 mm or 120 mm, and a signal recording layer 102b formed on one main surface portion of the transparent substrate 102a. And is configured.

  This second type of optical disk 102 is configured such that an information signal can be written and read by an objective lens having a numerical aperture of 0.45 by a laser beam having a wavelength of 780 nm, which is the second wavelength. . In the signal recording layer, the information signal is recorded along a recording track formed in a substantially concentric spiral shape.

  For example, so-called “compact disc (CD)” (trade name), so-called “CD-ROM”, and “CD-R” have been proposed as the second type of optical disc 102.

  Note that a write-once optical disc having a transparent substrate with a thickness of 1.2 mm, so-called “CD-R”, has a high wavelength dependency at the time of reading an information signal, so that the recording density of the information signal is increased. Information signals cannot be read out using a light source with a shorter emission wavelength. That is, the so-called “CD-R” signal recording layer is formed of an organic dye-based material, and absorbs a light beam having a shorter wavelength, for example, a light beam having a wavelength of 635 nm to 650 nm, thereby increasing the reflectance. As a result, the information signal cannot be read out by such a light beam having a shorter wavelength.

These first-type or second-type optical discs 101 and 102 are attached to the chassis 28 as shown in FIGS. 3 and 8 in the disc player according to the present invention configured to include the optical pickup according to the present invention. The spindle motor 27 is rotated. A disk table 25 serving as a recording medium holding mechanism is attached to the drive shaft 27 a of the spindle motor 27. The disk table 25 is formed in a substantially disc shape, and has a substantially truncated cone-shaped protrusion 26 in the center of the upper surface portion. When the central portion of each of the optical discs 101 and 102 is placed on the disc table 25, the projection 26 is fitted into a chucking hole provided in the central portion of the optical discs 101 and 102. 102 is configured to hold the central portion. That is, the optical disks 101 and 102 are held on the disk table 25 and are rotated together with the disk table 25 by the spindle motor 27.
[2] Outline of configuration of optical pickup
As shown in FIGS. 3 and 8, the optical pickup according to the present invention has an optical system block 17 movably supported by a guide shaft 23 and a support shaft 24 disposed on the chassis 28. Configured. The guide shaft 23 and the support shaft 24 are arranged in parallel with each other, and are arranged in parallel with the upper surface portion of the disk table 25.

  As shown in FIGS. 1 and 2, the optical system block 17 includes guide holes 20 and 20 through which the guide shaft 23 is inserted, and a support groove 21 into which the support shaft 24 is inserted. The optical system block 17 is moved along the guide shaft 23 and the support shaft 24 so that the upper surface portion faces the main surface portions of the optical disks 101 and 102 mounted on the disk table 25. Thus, it is moved in the contact / separation direction with respect to the spindle motor 27, that is, in the radial direction of the optical discs 101 and 102. As shown in FIG. 8, the optical system block 17 is moved and operated via a rack gear 29 by a thread motor 30 disposed on the chassis 28.

The positional relationship between the optical system block 17 and the spindle motor 27, that is, the positional relationship between the optical system block 17 and the optical discs 101 and 102 is determined by moving the optical system block 17 while fixing the spindle motor 27. May be changed by moving the spindle motor 27 while the optical system block 17 is fixed, and both the optical system block 17 and the spindle motor 27 may be changed. It is good also as changing by each moving operation.
[3] Configuration of Biaxial Actuator By the way, the transparent substrate of the optical discs 101 and 102 is formed in a flat plate shape, but may have a slight distortion. Therefore, the central portion is held by the disc table 25. Cause a so-called run-out. That is, the signal recording layers of the optical discs 101 and 102 periodically move in a direction in which the optical discs 101 and 102 are moved toward and away from the optical pickup when the central portions are held and rotated. The recording tracks of the optical discs 101 and 102 are formed so that the center of curvature coincides with the center of the transparent substrate, but may have a slight eccentricity. Therefore, the transparent substrate holds the central portion. When the optical disk 101 is rotated, the optical disks 101 and 102 are periodically moved in the radial direction.

  In order to follow the movement of the recording track due to such surface wobbling or eccentricity of the optical discs 101 and 102, the laser beam for writing and reading information signals to and from these optical discs 101 and 102 is followed. As shown in FIGS. 1 and 2, the pickup includes a biaxial actuator 19. The biaxial actuator 19 is attached to the upper surface of the optical system block 17.

  The biaxial actuator 19 causes the first and second objective lenses 7a and 7b to be orthogonal to the optical axis directions of the objective lenses 7a and 7b, that is, the focus direction indicated by the arrow F in FIG. It is supported so as to be movable in the direction, that is, the tracking direction indicated by the arrow T in FIG. These objective lenses 7a and 7b are made to oppose the signal recording layers of the optical disks 101 and 102 mounted on the disk table 25, and the optical system block 17 moves along the guide shaft 23 and the support shaft 24. By being operated, as shown by an arrow S in FIG. 3, the optical disk 101, 102 is moved over the inner and outer circumferences. The first and second objective lenses 7 a and 7 b are arranged in a direction substantially orthogonal to the longitudinal direction of the guide shaft 23, that is, in the circumferential direction of the optical disks 101 and 102 mounted on the disk table 25. Yes.

  As shown in FIGS. 6 and 7, the biaxial actuator 19 has a columnar support shaft 15 erected substantially vertically on the base plate 16 soil. The biaxial actuator 19 has a substantially disc-shaped lens bobbin 8 serving as a movable portion to which the objective lenses 7a and 7b are attached. The lens bobbin 8 has a bearing hole 37 in the center, and the support shaft 15 is inserted into the bearing hole 37 to slide in the axial direction of the support shaft 15 and around the axis of the support shaft 15. Can be rotated and supported by the support shaft 15. The objective lenses 7 a and 7 b have an optical axis parallel to the support shaft 15. The objective lenses 7 a and 7 b are disposed at positions that are substantially symmetrical about the bearing hole 37 at positions spaced from the bearing hole 37. Therefore, when the lens bobbin 8 is moved with respect to the support shaft 15, the objective lenses 7a and 7b are moved in the optical axis direction of the objective lenses 7a and 7b indicated by the arrow F in FIG. The movement operation is performed in the direction and the direction perpendicular to the optical axis of the objective lenses 7a and 7b and the tangent line of the recording track indicated by the arrow T in FIG.

  The lens bobbin 8 is provided with focus drive coils 12 and 12 and tracking drive coils 13 and 13 which are drive coils, respectively. A pair of the focus drive coils 12, 12 are attached to both side portions of the lens bobbin 8 with the winding axis direction being the radial direction of the lens bobbin 8. These focus drive coils 12 and 12 are disposed at positions that are symmetric with respect to the support shaft 15. The tracking drive coils 13 and 13 are also attached to a pair of side surfaces of the lens bobbin 8 with the winding axis direction being the radial direction of the lens bobbin 8. These tracking drive coils 13 and 13 are disposed at positions that are symmetric with respect to the support shaft 15. One focus drive coil 12 and one tracking drive coil 13 are adjacent to each other on the side surface of the coil bobbin 8. The other focus drive coil 12 and the other tracking drive coil 13 are adjacent to each other on the side surface of the coil bobbin 8.

  A focus midpoint maintaining contact piece 22a is attached to the side surface of the lens bobbin 8 so as to be positioned substantially at the center of the focus drive coils 12 and 12. The focus middle point maintaining contact piece 22a is made of a magnetic material. A tracking midpoint maintaining contact piece 22b is attached to the side surface of the lens bobbin 8 so as to be positioned substantially at the center of the tracking drive coils 13 and 13. The tracking midpoint maintaining contact piece 22b is formed of a magnetic material.

  The biaxial actuator 19 has a magnetic circuit that positions the drive coils 12, 12, 13, and 13 in a magnetic field. This magnetic circuit corresponds to a pair of focus drive yokes 9a and 9a and a pair of tracking drive yokes 9b and 9b that are erected on the base plate 16, respectively, and the yokes 9a, 9a, 9b, and 9b. It consists of two attached magnets 10, 10, 11, and 11. Each of the yokes 9a, 9a, 9b, 9b is formed integrally with the base plate 16 by bending the peripheral side portion of the base plate 16 made of a magnetic material upward. . Each of the yokes 9a, 9a, 9b, 9b has a main surface portion facing the center side of the base plate 16 opposed to a side surface portion on the outer peripheral side of the lens bobbin 8.

  The magnets 10, 10, 11, and 11 are attached to the main surface portions of the yokes 9a, 9a, 9b, and 9b facing the center side of the base plate 16, respectively. These magnets 10, 10, 11, and 11 are each one-sided dipole magnetized, and each magnetic pole is made to face the focus drive coils 12 and 12 and the tracking drive coils 13 and 13, and is generated from this magnetic pole. The focus drive coils 12 and 12 and the tracking drive coils 13 and 13 are positioned in a magnetic field.

  The magnetic fields formed by the focus drive magnets 10 and 10 attached to the focus drive yokes 9a and 9a are loop magnetic fields extending from the upper end side to the lower end side of the focus drive magnets 10 and 10, respectively. The magnetic field formed by the tracking drive magnets 11 and 11 attached to the tracking drive yokes 9b and 9b is a loop-shaped magnetic field extending from one side to the other end side of the tracking drive magnets 11 and 11.

  In this biaxial actuator, when a drive current is supplied to the focus drive coils 12, 12, the lens bobbin 8 is acted on by a magnetic field formed by the magnetic circuit, as indicated by an arrow F in FIG. The moving operation is performed in the axial direction of the support shaft 15, that is, in the focus direction (the optical axis direction of the objective lenses 7a and 7b).

  Further, in this biaxial actuator 19, when a drive current is supplied to the tracking drive coils 13, 13, the lens bobbin 8 is acted on by a magnetic field formed by the magnetic circuit, and an arrow T in FIG. As shown in the figure, the objective lens 7a, 7b is rotated around the axis of the support shaft 15 to move the objective lens 7a, 7b in a tracking direction (a direction orthogonal to the optical axis of the objective lens 7a, 7b).

  That is, the biaxial actuator 19 is supplied with a focus drive current based on a focus error signal, which will be described later, to the focus drive coils 12 and 12, and the objective lenses 7a and 7b follow the surface shake of the optical discs 101 and 102. To move. The biaxial actuator 19 is supplied with a tracking drive current based on a tracking error signal, which will be described later, to the tracking drive coils 13 and 13 so that the objective lenses 7a and 7b are decentered in the recording tracks of the optical disks 101 and 102. Move to follow.

In the biaxial actuator 19, the focus bobbin 8 is attracted to the position where the magnetic flux density in the magnetic field formed by the focus driving magnet 10 is the highest, so that the coil bobbin 8 is It is held at the midpoint with respect to the focus direction. In the biaxial actuator 19, the tracking bobbin 8 is attracted to the highest magnetic flux density position in the magnetic field formed by the tracking drive magnet 11 so that the coil bobbin 8 is It is held at the midpoint in the tracking direction.
[4] Configuration of Optical System Block In the optical system block 17, as shown in FIG. 2, a laser coupler (light emission) having a semiconductor laser 1 serving as a first light source and a semiconductor laser chip 42 serving as a second light source. A light receiving composite element) 6 is incorporated. The semiconductor laser 1 and the semiconductor laser chip 42 emit first and second laser beams, which are linearly polarized coherent lights, respectively. These laser light beams are divergent light beams. The wavelength of the first laser beam emitted from the semiconductor laser 1 is 635 nm or 650 nm, which is the first wavelength. The wavelength of the second laser beam emitted from the semiconductor laser chip 42 is 780 nm, which is the second wavelength.

  As shown in FIG. 4, the first laser beam emitted from the semiconductor laser 1 enters a flat beam splitter 3 through a grating (diffraction grating) 2 serving as an optical diffraction element. The grating 2 splits the first laser light beam into three laser light beams of zero-order light and ± first-order light. The beam splitter 3 is arranged with the main surface portion at an angle of 45 ° with respect to the optical axis of the first laser beam. The beam splitter 3 transmits a part of the first laser beam, but reflects the remaining part. The first laser beam reflected by the beam splitter 3 is incident on the collimator lens 4, and is converted into a first parallel laser beam by the collimator lens 4.

  The first parallel laser light beam that has passed through the collimator lens 4 is emitted to the outer side of the optical system block 17 through a first through hole provided in the outer casing portion of the optical system block 17. The first parallel laser beam is incident on the first objective lens 7a. The first objective lens 7 a condenses the first parallel laser light beam on the signal recording layer of the first type optical disk 101.

  As shown in FIG. 5, the laser coupler 6 includes the semiconductor laser chip 42 and the first and second photodetectors 45 and 46 disposed on the same semiconductor substrate 40. The semiconductor laser chip 42 is disposed on the semiconductor substrate 40 via a heat sink 41. Each of the photodetectors 45 and 46 is formed on the semiconductor substrate 40 in a state of being divided into a plurality of light receiving surfaces.

  In the laser coupler 6, a beam splitter prism 43 is disposed on the photodetectors 45 and 46. The beam splitter prism 43 has a beam splitter surface 44, which is an inclined surface having a predetermined inclination angle with respect to the upper surface of the semiconductor substrate 40, facing the semiconductor laser chip 42 side.

  In the laser coupler 6, the semiconductor laser chip 42 emits the second laser light beam toward the beam splitter surface 44. The second laser beam emitted from the semiconductor laser chip 42 is reflected by the beam splitter surface 44 and is emitted vertically upward with respect to the semiconductor substrate portion 40.

The second laser light beam emitted from the laser coupler 6 is emitted to the outer side of the optical system block 17 through a second through hole provided in the outer casing portion of the optical system block 17. The The second parallel laser light beam is incident on the second objective lens 7b. The second laser beam incident on the second objective lens 7b passes through the transparent substrate 102a of the second type optical disk 102 by the second objective lens 7b and passes through the second type optical disk 102. Is condensed on the surface of the signal recording layer 102b. The first through hole and the second through hole are formed at substantially symmetrical positions around the support shaft 15.
A skew sensor 18 serving as a substrate thickness detecting unit is attached to the upper surface portion of the optical system block 17. The skew sensor 18 includes a light emitting element such as an LED and a plurality of light receiving elements such as a photodiode.

  The skew sensor 18 irradiates the light emitted from the light emitting element onto the optical disk mounted on the disk table 25, and detects the position (intensity distribution) of the reflected light of the light from the optical disk by the light receiving element. The optical disk tilt (skew) and the thickness of the transparent substrate of the optical disk can be detected.

  In the optical system block 17, as shown in FIG. 20, a first semiconductor laser 1 serving as a first light source and a second semiconductor laser 1a serving as a second light source may be incorporated. . Each of the semiconductor lasers 1 and 1a emits first and second laser beams that are linearly polarized coherent light. These laser light beams are divergent light beams. The wavelength of the first laser beam emitted from the first semiconductor laser 1 is the first wavelength of 635 nm or 650 nm. The wavelength of the second laser beam emitted from the second semiconductor laser 1a is 780 nm, which is the second wavelength.

  The first laser beam emitted from the first semiconductor laser 1 enters a flat beam splitter 3 via a grating (not shown). The grating branches the first laser light beam into three laser light beams of zero-order light and ± first-order light. The beam splitter 3 is arranged with the main surface portion at an angle of 45 ° with respect to the optical axis of the first laser beam. The beam splitter 3 transmits a part of the first laser beam, but reflects the remaining part. The first laser beam reflected by the beam splitter 3 is emitted to the outer side of the optical system block 17 through a through hole provided in the upper surface portion of the optical system block 17. Then, the first laser beam is incident on the first objective lens 7 a supported by the biaxial actuator 19. The first objective lens 7 a condenses the first laser beam on the signal recording layer of the first type optical disk 101.

  Then, the first laser beam reflected by the surface of the signal recording layer of the first type optical disc 101 passes through the first objective lens 7a and the beam splitter 3 and is received by the first photodetector 5. The

  The second laser beam emitted from the second semiconductor laser 1a is incident on the plate-shaped beam splitter 3a. The beam splitter 3a is arranged with the main surface portion at an angle of 45 ° with respect to the optical axis of the second laser beam. The beam splitter 3a transmits a part of the second laser beam, but reflects the remaining part. The second laser beam reflected by the beam splitter 3a is emitted to the outer side of the optical system block 17 through a through hole provided in the upper surface portion of the optical system block 17. The second laser beam is incident on the second objective lens 7 b supported by the biaxial actuator 19. The second objective lens 7 b condenses the second laser beam on the signal recording layer of the second type optical disk 102.

  Then, the second laser beam reflected by the surface of the signal recording layer of the second type optical disc 102 passes through the second objective lens 7b and the beam splitter 3a and is received by the second photodetector 5a. The

  Further, as shown in FIG. 24, this optical pickup has a first optical path from the first semiconductor laser 1 to the first objective lens 7a and a second one from the second semiconductor laser 1a in the optical system block 17. The second optical path to the objective lens 7b may intersect with each other at the intersection X. The intersection point X is located between the beam splitter 3 and the first reflection mirror 36a on the first optical path.

  As shown in FIG. 25, the first reflection mirror 36a is for deflecting the first laser beam and making it incident on the first objective lens 7a. The intersection point X is located between the beam splitter 3a and the second reflection mirror 36b on the second optical path. As shown in FIG. 25, the second reflection mirror 36b is for deflecting the second laser light beam and making it incident on the second objective lens 7b.

  In this optical pickup, since the optical paths intersect each other, the total volume occupied by the optical paths is reduced by the overlapping of the optical paths. Therefore, in this optical pickup, the size in the arrangement direction of the objective lenses 7a and 7b of the optical system block 17 indicated by the arrow W in FIG. 24 can be reduced.

  Further, as shown in FIG. 26, the first and second light fluxes in the optical system block 17 may not be provided with the reflection mirror in one of these optical paths. That is, the first laser beam emitted from the first semiconductor laser is incident on the plate-shaped beam splitter 3. The beam splitter 3 is arranged with the main surface portion at an angle of 45 ° with respect to the optical axis of the first laser beam. The beam splitter 3 transmits a part of the first laser beam and reflects the remaining part. The first laser light beam reflected by the beam splitter 3 is reflected by the reflection mirror 36a, and the outer side of the optical system block 17 is passed through a through hole provided in the upper surface portion of the optical system block 17. Is injected into. The first laser beam is incident on the first objective lens 7a. The first objective lens 7 a condenses the first laser beam on the signal recording layer of the first type optical disk 101.

  Then, the second laser beam emitted from the second semiconductor laser 1a in the optical system block 17 is incident on the plate-shaped beam splitter 3a. The beam splitter 3a is arranged with the main surface portion at an angle of 45 ° with respect to the optical axis of the second laser beam. The beam splitter 3a transmits a part of the second laser beam and reflects the remaining part. The second laser beam reflected by the beam splitter 3a is emitted to the outer side of the optical system block 17 through a through hole provided in the upper surface portion of the optical system block 17. The second laser light beam is incident on the second objective lens 7b. The second objective lens 7 b condenses the second laser beam on the signal recording layer of the second type optical disk 102.

  Here, the first optical path from the first semiconductor laser 1 to the first objective lens 7a and the second optical path from the second semiconductor laser 1a to the second objective lens 7b are: At the intersection point X, the optical axes intersect each other. The intersection point X is located between the beam splitter 3 and the reflection mirror 36a on the first optical path. The intersection point X is located between the beam splitter 3a and the second objective lens 7b on the second optical path.

Also in this optical pickup, since the respective optical paths intersect each other, the total volume occupied by these optical paths is reduced by the overlap of the optical paths. Therefore, also in this optical pickup, the size of the optical system block 17 can be reduced.
[5] Configuration of Disc Player As shown in FIG. 21, the disc player according to the present invention includes a discriminating means (discriminating circuit) 52 for discriminating the type of the disc-shaped optical recording medium mounted on the disc table 25, and a control circuit. A CPU (Central Processing Unit) 32 and a controller 53 that performs various controls in accordance with signals sent from the CPU 32.

  When the first type optical disk 101 is mounted on the disk table 25, the disc-shaped optical recording medium mounted by the discriminating means 52 is determined based on the reading result of the identification label of the first type optical disk 101, so-called ID. It is determined that the optical disk 101 is the first type, and a determination signal is sent to the controller 53 via the CPU 32.

  The controller 53 sends drive signals to the laser drive circuit 54 and the biaxial actuator drive circuit 55 based on the sent discrimination signal, respectively, to drive the first semiconductor laser 1 and the biaxial actuator 19. Then, the first laser beam is emitted from the first semiconductor laser 1, and the information signal is read from the first type optical disk 101 via the first photodetector 5.

  When the second type optical disk 102 is mounted on the disk table 25, the disc-shaped optical recording mounted by the discriminating means 52 based on the result of reading the identification label of the second type optical disk 102, the so-called ID. It is determined that the medium is the second type optical disk 102, and a determination signal is sent to the controller 53 via the CPU 32.

  Based on the sent discrimination signal, the controller 53 sends drive signals to the laser drive circuit 56 and the biaxial actuator drive circuit 55, respectively, to drive the second semiconductor laser 1a and the biaxial actuator 19. Then, a second laser beam is emitted from the second semiconductor laser 1a, and an information signal is read from the second type optical disk 102 via the second photodetector 5a.

  Even when any one of the optical disks 101 and 102 is mounted on the disk table 25, the output signals from the photodetectors 5 and 5a are sent to the focusing error signal detection circuit 57a and the tracking error signal detection circuit 57b. The output signals from these photodetectors 5 and 5a include a focus error signal and a tracking error signal in addition to the read signal. Each of the error signal detection circuits 57a and 57b detects a focus error signal and a tracking error signal from the transmitted signal. These focus error signal and tracking error signal are sent from the error signal detection circuit 57 to the biaxial actuator drive circuit 55. The biaxial actuator 19 is driven based on a focus error signal and a tracking error signal.

  In the disc player, as shown in FIG. 8, the detection output obtained by the skew sensor 18 is sent to a control circuit (CPU) 32 serving as control means. The control circuit 32 is also supplied with a signal output from the optical pickup and a detection signal from an inner sensor switch 31 that detects that the optical pickup is at a position closest to the spindle motor 27. The control circuit 32 controls the pickup driver 34, the spindle motor driver 35, and the thread motor driver 33 including the actuator driving circuit 55 according to various signals that are sent. The pickup driver 34 controls driving of the biaxial actuator 19 in the optical pickup, light emission and extinction of the semiconductor laser 1 and the semiconductor laser chip 42. The spindle motor driver 35 controls the rotational drive of the spindle motor 27. The thread motor driver 33 controls the rotational drive of the thread motor 30.

  When the control circuit 32 determines that the first type of optical disk 101 is mounted on the disk table 25 based on the detection output sent from the skew sensor 18, the semiconductor laser 1 is emitted, and the semiconductor laser chip 42 or the second semiconductor laser 1a is quenched. At this time, the first laser light beam that has passed through the first objective lens 7a is applied to the first type optical disc 101 from the transparent substrate side of the first type optical disc 101, and is transmitted through the transparent substrate. Then, the light is condensed on the signal recording layer. The first objective lens 7a is moved and operated by the biaxial actuator 19 in the direction of the optical axis of the first objective lens 7a and in the direction perpendicular to the optical axis. The first objective lens 7a is moved and operated by the biaxial actuator 19 following the displacement of the first objective optical disc 101 in the optical axis direction (so-called surface vibration). Thus, the condensing point of the laser beam is always positioned on the signal recording layer. The first objective lens 7a is moved by the biaxial actuator 19 following the displacement of the recording track of the first type optical disc 101 in the direction perpendicular to the optical axis of the first objective lens 7a. By being operated, the condensing point of the first laser beam is always positioned on the recording track.

  This optical pickup collects and irradiates the first laser beam on the signal recording layer of the first type optical disc 101, thereby writing and reading information signals on the signal recording layer. In the writing of the information signal, when the first type optical disk 101 is a magneto-optical disk, the magneto-optical disk is irradiated with the first laser light beam and the first laser light beam An external magnetic field is applied to the irradiation position. Information signals are written to the magneto-optical disk by modulating either the optical output of the first laser beam or the intensity of the external magnetic field in accordance with the information signal to be recorded. When the first type optical disc 101 is a phase change type disc, the information signal for the phase change type disc is modulated by modulating the light output of the first laser beam in accordance with the information signal to be recorded. Is written.

In this optical pickup, the first laser beam is condensed and irradiated on the signal recording layer of the first type optical disc 101, and the reflected beam of the laser beam by the signal recording layer is detected. Thus, the information signal is read from the signal recording layer.
In the reading of the information signal, when the first type optical disk 101 is a magneto-optical disk, the information signal is read from the magneto-optical disk by detecting a change in the polarization direction of the reflected light beam. Is called. When the first type optical disc 101 is a phase change type disc or a so-called pit disc, the information signal is read by detecting a change in the amount of reflected light of the reflected light beam.

  That is, the first laser beam condensed on the signal recording layer is reflected by the signal recording layer and returns to the first objective lens 7a as a reflected beam. The reflected light beam that has returned to the first objective lens 7a is converted into a parallel light beam by the first objective lens 7a, and returns to the beam splitter 3 through the collimator lens 4. The reflected light beam that has returned to the beam splitter 3 passes through the beam splitter 3 and is branched to the optical path that returns to the semiconductor laser 1 and travels toward the photodetector 5.

  Since the beam splitter 3 is a parallel plane plate inclined at an angle of 45 ° with respect to the optical axis of the reflected light beam, astigmatism is generated in the reflected light beam. When the first type optical disc 101 is a magneto-optical disc, the reflected light beam that has passed through the beam splitter 3 enters the photodetector 5 through a Wollaston prism. The Wollaston prism includes a reflected light beam, a first polarization component that is polarized light in a polarization direction of the reflected light beam, and a second polarization component that is polarized light in a + 45 ° direction with respect to the polarization direction of the reflected light beam. And the third polarization component that is polarized in the direction of −45 ° with respect to the polarization direction of the reflected light beam.

  The photodetector 5 includes a plurality of photodiodes corresponding to a plurality of light beams branched by the grating 2 and the Wollaston prism, and receives each light beam by a corresponding photodiode. Has been made. By calculating the light detection output from each photodiode of the photodetector 5, a read signal, a focus error signal, and a tracking error signal of an information signal recorded on the magneto-optical disk are generated. The focus error signal is generated by the first objective lens 7a between the focal point of the first laser beam by the first objective lens 7a and the surface portion of the signal recording layer of the first type optical disc 101. It is a signal which shows the amount and direction of position shift in the optical axis direction. The tracking error signal is orthogonal to the optical axis of the first objective lens 7a between the condensing point of the first laser beam by the first objective lens 7a and the recording track of the first type optical disc 101. It is a signal which shows the amount and direction of position shift of the direction to do. The biaxial actuator 19 is driven based on these focus error signal and tracking error signal.

In the photodetector 5, the photodiodes that receive the reflected light beam from the signal recording layer of the zero-order light of the first laser light beam have four photodiodes arranged radially about the optical axis of the reflected light beam. It has a light receiving surface portion. A beam spot formed by the reflected light beam on the light receiving surfaces of these four photodiodes is an elliptical beam spot whose major axis direction is a direction corresponding to the direction of astigmatism generated by the beam splitter 3. Become. Here, if the light detection outputs from the four light receiving surface portions are a, b, c, and d, respectively,
Fe = (a + c) − (b + d)
Is a signal indicating the direction and amount of astigmatism of the reflected light beam. This Fe is a focus error signal, and is a signal indicating the distance and direction between the condensing point of the first laser beam by the first objective lens 7a and the signal recording surface of the first type optical disc 101. It has become.

  The biaxial actuator 19 is driven based on the focus error signal Fe to move the first objective lens 7a, thereby condensing the first laser beam by the first objective lens 7a. A focus servo operation is performed so that is always positioned on the signal recording surface.

In the photodetector 5, the photodiode that receives the reflected light beam from the signal recording layer of the ± first-order light of the first laser light beam has two light receiving surface portions independent of each other. ing. The light amounts of the reflected light beams of the ± first-order light are equal to each other when the condensing point of the first-order light of the first laser light beam by the first objective lens 7a is on the recording track. Here, if the light detection outputs from the two light receiving surface portions are e and f, respectively,
Te = ef
Is a signal indicating the difference in the amount of reflected light flux of the ± primary light. This Te is a tracking error signal, and the distance and direction between the condensing point of the zero-order light of the first laser beam by the first objective lens 7a and the recording track of the first type optical disc 101. It is a signal indicating.

  The biaxial actuator 19 is driven on the basis of the tracking error signal Te and moves the first objective lens 7a, whereby the zero-order light of the first laser beam by the first objective lens 7a. A tracking servo operation for always positioning the light condensing point on the recording track is executed.

  The optical pickup is moved along the guide shaft 23 and the support shaft 24, so that the first objective lens 7a extends over the entire signal recording area of the first type optical disc 101. By performing the moving operation so as to face each other, the information signal can be written and read over the entire signal recording area. That is, the optical pickup is moved over the inner and outer circumferences of the first type optical disc 101, and the signal of the first type optical disc 101 is operated by rotating the first type optical disc 101. Information signals can be written and read over the entire recording area.

  By the way, in this optical pickup, the detection of the tracking error signal for the first type optical disc 101 is performed by the so-called three-beam method as described above. Therefore, in this optical pickup, as shown in FIG. 3, the first objective lens 7a is opposed to a straight line passing through the center of the first type optical disc 101, that is, the center of the disc table 25, That is, the moving operation is performed over the inner and outer circumferences of the first type optical disc 101 in a state where the optical axis intersects with a straight line passing through the center of the first type optical disc 101.

The control circuit 32 determines that the second type of optical disk 102 is mounted on the disk table 25 based on the detection output sent from the skew sensor 18. The chip 42 or the second semiconductor laser 1a emits light, and the semiconductor laser 1 is quenched. At this time, the second laser light beam that has passed through the second objective lens 7b is irradiated onto the second type optical disc 102 from the transparent substrate side of the second type optical disc 102 and transmitted through the transparent substrate 102a. Then, the light is condensed on the signal recording layer 102b. The second objective lens 7b is moved and operated by the biaxial actuator 19 in the direction of the optical axis of the second objective lens 7b and the direction perpendicular to the optical axis. The second objective lens 7b is moved and operated by the biaxial actuator 19 following the displacement of the second type of optical disk 102 in the optical axis direction (so-called surface vibration). Thus, the focal point of the second laser beam is always positioned on the signal recording layer 102b. The second objective lens 7b follows the displacement of the recording track of the second type optical disc 102 in the direction perpendicular to the optical axis of the second objective lens 7b by the biaxial actuator 19. When the moving operation is performed, the condensing point of the second laser beam is always positioned on the recording track.

  This optical pickup reads the information signal from the signal recording layer 102b by condensing and irradiating the second laser beam onto the signal recording layer 102b of the second type optical disc 102. That is, in this optical pickup, the second laser beam is condensed and irradiated on the signal recording layer 102b of the second type optical disk 102, and the reflection of the second laser beam by the signal recording layer 102b. By detecting the light flux, the information signal is read from the signal recording layer 102b. This information signal is read by detecting a change in the amount of reflected light of the reflected light beam.

  That is, the second laser beam condensed on the surface portion of the signal recording layer 102b is reflected by the signal recording layer 102b and returns to the second objective lens 7b. The reflected light beam that has returned to the second objective lens 7 b returns to the beam splitter surface 44.

  The reflected light beam that has returned to the beam splitter surface 44 passes through the beam splitter surface 44 and enters the beam splitter prism 43, and is branched off from the optical path that returns to the semiconductor laser chip 42. Light is received by the detector 45. The reflected light beam is reflected by the surface portion of the first photodetector 45 and the inner surface portion 47 of the beam splitter prism 43 and is also received by the second photodetector 46.

  Based on the light detection outputs output from the light detectors 45 and 46, the read signal (RF signal) of the information signal recorded on the second type optical disc 102, the second objective lens 7b and the second objective lens 7b. A focus error signal Fe indicating a deviation (focus error) in the optical axis direction between the condensing point of the laser beam 2 and the surface portion of the signal recording layer 102b, and the condensing point and the surface portion of the signal recording layer 102b. A tracking error signal Te indicating a deviation (tracking error) in the direction perpendicular to the optical axis and the recording track with respect to the recording track formed on the recording track is calculated.

  That is, the readout signal (RF signal) is obtained as the sum of the light detection outputs of the light detectors 45 and 46. The focus error signal Fe is obtained as a difference between the light detection outputs of the light detectors 45 and 46.

  Further, the tracking error signal Te is detected by the light detection output (A) from the light receiving surface on one side of the first light detector 45 and the light detection from the light receiving surface on the other side of the second light detector 45. The sum of outputs (D), the light detection output (B) from the light receiving surface on the other side of the first light detector 45, and the light detection output from the light receiving surface on one side of the second light detector 45 It is obtained as a difference ((A + D)-(B + C)) with the sum of (C).

  That is, in this optical pickup, the tracking error signal is detected by the so-called push-pull method of the so-called one-beam method for the second type optical disk 102.

  In each of the photodetectors 45 and 46, the dividing line between the light receiving surface on one side and the light receiving surface on the other side is an angle of 45 ° with respect to the tangential direction of the recording track in the second type optical disc 102. It is made to make.

The first photodetector 45 has a light receiving surface on one side divided into first and third light receiving portions A ₁ and A ₃ (light detection outputs A ₁ and A ₃ ), and a light receiving surface on the other side. Is divided into second and fourth light receiving portions A ₂ and A ₄ (light detection outputs A ₂ and A ₄ ), which are divided into four in total. In the second photodetector 46, the light receiving surface on one side is divided into first and third light receiving parts B ₁ and B ₃ (light detection outputs B ₁ and B ₃ ), and the light receiving surface on the other side. Is divided into second and fourth light receiving parts B ₂ and B ₄ (light detection outputs B ₂ and B ₄ ), for a total of four. Therefore, the tracking error signal Te is obtained from the light detection output of each light receiving unit.
(A ₂ + A ₄ + B ₁ + B ₃ ) − (A ₁ + A ₃ + B ₂ + B ₄ )
Is obtained.

  The optical pickup is moved along the guide shaft 23 and the support shaft 24 so that the second objective lens 7b extends over the entire signal recording area of the second type optical disk 102. By performing the movement operation so as to face each other, the information signal can be read from the entire signal recording area. That is, the optical pickup is operated to move over the inner and outer circumferences of the second type optical disc 102, and the second type optical disc 102 is rotated to operate the signal of the second type optical disc 102. Information signals can be read from the entire recording area.

In the disc player according to the present invention, the substrate thickness detecting means is not limited to the sensor used also as the skew sensor 18 as described above, but based on the amplitude of the RF signal read from the disc-shaped optical recording medium. It may be determined by the control circuit 32. That is, when one of the first type and the second type optical disks 101 and 102 is mounted on the disk table 25, one of the first and second light sources set in advance. To emit light. At this time, if only the focus servo is operated, the amplitude of the RF signal can be detected, and it is detected which of the first and second light sources is emitting light. Based on the amplitude of the received RF signal, it can be determined which of the first type and the second type of optical disks 101 and 102 is mounted on the disk table 25.
[6] Other forms of the configuration of the biaxial actuator (1)
In the optical pickup according to the present invention, the biaxial actuator 19 includes a focus coil 12 wound on the outer peripheral surface of the coil bobbin 8 as shown in FIGS. 9 to 12. Also good.

  Similarly to the biaxial actuator described above, the biaxial actuator 19 also moves the first and second objective lenses 7a and 7b in the direction of the optical axis of the objective lenses 7a and 7b, that is, by the arrow F in FIG. It is supported so as to be movable in the focus direction shown and the direction orthogonal to the optical axis, that is, the tracking direction shown by the arrow T in FIG. The objective lenses 7a and 7b are opposed to the signal recording layers of the optical disks 101 and 102 mounted on the disk table 25 by mounting the optical pickup 19 on the optical block 17, and the optical system. When the block 17 is moved along the guide shaft 23 and the support shaft 24, the block 17 is moved over the inner and outer circumferences of the optical disks 101 and 102. The first and second objective lenses 7 a and 7 b are arranged in a direction substantially orthogonal to the longitudinal direction of the guide shaft 23, that is, in the circumferential direction of the optical disks 101 and 102 mounted on the disk table 25. Yes.

  As shown in FIGS. 9 and 10, the biaxial actuator 19 has a columnar support shaft 15 erected substantially vertically on a base plate 16. The biaxial actuator 19 has a substantially disc-shaped lens bobbin 8 serving as a movable portion to which the objective lenses 7a and 7b are attached. The lens bobbin 8 has a bearing hole 37 in the center, and the support shaft 15 is inserted into the bearing hole 37 to slide in the axial direction of the support shaft 15 and around the axis of the support shaft 15. Can be rotated and supported by the support shaft 15. The objective lenses 7 a and 7 b have an optical axis parallel to the support shaft 15. The objective lenses 7 a and 7 b are disposed at positions that are substantially symmetrical about the bearing hole 37 at positions spaced from the bearing hole 37. Therefore, when the lens bobbin 8 is moved with respect to the support shaft 15, the objective lenses 7a and 7b are moved in the optical axis direction of the objective lenses 7a and 7b indicated by the arrow F in FIG. The moving operation is performed in the direction and the direction perpendicular to the optical axis of the objective lenses 7a and 7b and the tangent line of the recording track, indicated by the arrow T in FIG.

  The lens bobbin 8 is provided with a focus drive coil 12 and tracking drive coils 13 and 13, which are drive coils. The focus driving coil 12 is wound around the outer peripheral surface of the lens bobbin 8 with the winding axis direction as the axial direction of the support shaft 15. A pair of the tracking drive coils 13 and 13 are attached to both side portions of the lens bohin 8 with the winding axis direction as the radial direction of the lens bobbin 8. These tracking drive coils 13 and 13 are disposed at positions that are symmetric with respect to the support shaft 15.

  As shown in FIG. 12, a tracking midpoint maintaining contact piece 22b is attached to the side surface of the lens bobbin 8 so as to be positioned substantially at the center of the tracking drive coils 13 and 13. The tracking midpoint maintaining contact piece 22b is formed of a magnetic material.

  The biaxial actuator 19 has a magnetic circuit that positions the drive coils 12, 13, and 13 in a magnetic field. The magnetic circuit includes a pair of inner focus drive yokes 9a and 9aN which are provided upright on the base plate 16, and a pair of tracking drive yokes 9c and 9c and a pair of tracking drive yokes 9b and 9b. It consists of two pairs of magnets 10, 10, 11, 11 attached to the yokes 9a, 9a and the tracking drive yokes 9b, 9b. Each of the yokes 9a, 9a, 9c, 9c, 9b, 9b is formed integrally with the base plate 16 by bending a part of the base plate 16 made of a magnetic material upward. Has been. The pair of inner focus drive yokes 9 a, 9 a is disposed inside the outer peripheral wall of the lens bobbin 8. That is, the inner focus drive yokes 9a, 9a are arranged so as to enter the inner side of the focus drive coil 12 from the lower side of the lens bobbin 8, as shown in FIG. These inner focus drive yokes 9 a and 9 a are formed in an arc shape (a shape that is a part of a cylinder) corresponding to the outer peripheral side surface portion of the lens bobbin 8. The pair of outer focus drive yokes 9 c and 9 c are disposed outside the outer peripheral wall of the lens bobbin 8. The pair of inner focus drive yokes 9a and 9a and the pair of outer focus drive yokes 9c and 9c are opposed to each other. The tracking drive yokes 9b and 9b are respectively positioned on the outer side of the lens bobbin 8, and the main surface facing the center side of the base plate 16 faces the side surface on the outer peripheral side of the lens bobbin 8. I am letting.

  The focus driving magnets 10, 10 are attached to the outer side surfaces of the inner focus driving yokes 9a, 9a. The tracking drive magnets 11 and 11 are attached corresponding to the main surface portions of the tracking drive yokes 9b and 9b facing the center side of the base plate 16. The focus driving magnets 10 and 10 are respectively single-sided magnetized, and the tracking driving magnets 11 and 11 are respectively single-sided and double-pole magnetized. These magnets 10, 10, 11, 11 oppose the magnetic poles corresponding to the focus drive coil 12 and the tracking drive coils 13, 13, and the focus drive coil 12 and the tracking in the magnetic field generated from the magnetic poles. The drive coils 13 are positioned.

  The magnetic field formed by the focus drive magnets 10 and 10 attached to the inner focus drive yokes 9a and 9a crosses the focus drive coil 12 in the radial direction of the lens bobbin 8 and is applied to the outer focus drive yokes 9c and 9c. It is a radial magnetic field. The magnetic fields formed by the tracking drive magnets 11 and 11 attached to the tracking drive yokes 9b and 9b are loop magnetic fields extending from one side to the other side of the tracking drive magnets 11 and 11, respectively.

  In this biaxial actuator 19, when a driving current is supplied to the focus driving coil 12, the lens bobbin 8 is affected by the magnetic field formed by the magnetic circuit, and as shown by an arrow F in FIG. The moving operation is performed in the axial direction of the support shaft 15, that is, the focus direction, that is, the optical axis direction of the objective lenses 7a and 7b. In this biaxial actuator, when a drive current is supplied to the tracking drive coils 13 and 13, the lens bobbin 8 is acted on by a magnetic field formed by the magnetic circuit, and is indicated by an arrow T in FIG. As described above, the objective lens 7a, 7b is rotated around the axis of the support shaft 15 and moved in the tracking direction, that is, the direction orthogonal to the optical axis of the objective lens 7a, 7b.

  That is, the biaxial actuator 19 is supplied with a focus drive current based on the focus error signal to the focus drive coil 12, and moves the objective lenses 7a and 7b following the surface shake of the optical discs 101 and 102. Manipulate. The biaxial actuator 19 is supplied with a tracking drive current based on the tracking error signal to the tracking drive coils 13 and 13 so that the objective lenses 7a and 7b are eccentric to the recording tracks of the optical disks 101 and 102. Follow and move.

Further, in the biaxial actuator 19, the tracking bobbin 8 is attracted to a position having the highest magnetic flux density in the magnetic field formed by the tracking drive magnet 11 so that the coil bobbin 8 is It is held at the midpoint in the tracking direction.
[7] Other forms of the configuration of the biaxial actuator (2)
In the optical pickup according to the present invention, the biaxial actuator 19 may be configured to include a focus coil 12 wound around the lower portion of the coil bobbin 8, as shown in FIGS. .

  Similarly to the above-described biaxial actuator, the biaxial actuator 19 also moves the first and second objective lenses 7a and 7b in the optical axis direction of the objective lenses 7a and 7b, that is, by the arrow F in FIG. It is supported so as to be movable in the focus direction shown and the direction orthogonal to the optical axis, that is, the tracking direction shown by the arrow T in FIG. The objective lenses 7a and 7b are opposed to the signal recording layers of the optical disks 101 and 102 mounted on the disk table 25 by mounting the optical pickup 19 on the optical block 17, and the optical system. When the block 17 is moved along the guide shaft 23 and the support shaft 24, the block 17 is moved over the inner and outer circumferences of the optical disks 101 and 102. The first and second objective lenses 7 a and 7 b are arranged in a direction substantially orthogonal to the longitudinal direction of the guide shaft 23, that is, in the circumferential direction of the optical disks 101 and 102 mounted on the disk table 25. Yes.

  As shown in FIGS. 13 and 14, the biaxial actuator 19 has a columnar support shaft 15 erected substantially vertically on a base plate 16. The biaxial actuator 19 has a substantially disc-shaped lens bobbin 8 serving as a movable portion to which the objective lenses 7a and 7b are attached. The lens bobbin 8 has a bearing hole 37 in the center, and the support shaft 15 is inserted into the bearing hole 37 to slide in the axial direction of the support shaft 15 and around the axis of the support shaft 15. Can be rotated and supported by the support shaft 15. The objective lenses 7 a and 7 b have an optical axis parallel to the support shaft 15. The objective lenses 7 a and 7 b are disposed at positions that are substantially symmetrical about the bearing hole 37 at positions spaced from the bearing hole 37. Therefore, when the lens bobbin 8 is moved with respect to the support shaft 15, the objective lenses 7a and 7b are moved in the optical axis direction of the objective lenses 7a and 7b indicated by the arrow F in FIG. The moving operation is performed in the direction perpendicular to the optical axis of the objective lenses 7a and 7b and the tangent line of the recording track, that is, the tracking direction, indicated by the arrow T in FIG.

  The lens bobbin 8 is provided with a focus drive coil 12 and tracking drive coils 13 and 13, which are drive coils. The focus driving coil 12 is wound around the outer peripheral surface of the lens bobbin 8 with the winding axis direction as the axial direction of the support shaft 15. A pair of the tracking drive coils 13 and 13 are attached to both side portions of the lens bohin 8 with the winding axis direction as the radial direction of the lens bobbin 8. These tracking drive coils 13 and 13 are disposed at positions that are symmetric with respect to the support shaft 15.

  The biaxial actuator 19 has a magnetic circuit that positions the drive coils 12, 13, and 13 in a magnetic field. This magnetic circuit corresponds to a pair of focus drive yokes 9a and 9a and a pair of tracking drive yokes 9b and 9b that are erected on the base plate 16, respectively, and the yokes 9a, 9a, 9b, and 9b. It consists of two attached magnets 10, 10, 11, and 11. Each of the yokes 9a, 9a, 9b, 9b is formed integrally with the base plate 16 by bending a part of the base plate 16 made of a magnetic material upward. The focus drive yokes 9a and 9a are disposed so as to surround the outer side of the focus drive coil 12 from the lower side of the lens bobbin 8. These focus driving yokes 9a, 9a are formed in an arc shape (a shape that is a part of a cylinder) corresponding to the outer peripheral side surface portion of the lens bobbin 8. The tracking drive yokes 9b and 9b are positioned on the outer side of the lens bobbin 8, and the main surface facing the center side of the base plate 16 is opposed to the side surface on the outer peripheral side of the lens bobbin 8. I am letting.

  The focus driving magnets 10, 10 are attached to the inner side surfaces of the focus driving yokes 9a, 9a. The tracking drive magnets 11 and 11 are attached corresponding to the main surface portions of the tracking drive yokes 9b and 9b facing the center side of the base plate 16. The focus driving magnets 10 and 10 are respectively single-sided magnetized, and the tracking driving magnets 11 and 11 are respectively single-sided and double-pole magnetized. These magnets 10, 10, 11, 11 oppose the magnetic poles corresponding to the focus drive coil 12 and the tracking drive coils 13, 13, and the focus drive coil 12 and the tracking in the magnetic field generated from the magnetic poles. The drive coils 13 are positioned.

  The magnetic field formed by the focus drive magnets 10 and 10 attached to the focus drive yokes 9 a and 9 a is a radial magnetic field that crosses the focus drive coil 12 in the radial direction of the lens bobbin 8. The magnetic fields formed by the tracking drive magnets 11 and 11 attached to the tracking drive yokes 9b and 9b are loop magnetic fields extending from one side of the tracking drive magnets 11 and 11 to the other side.

  In the biaxial actuator 19, when a driving current is supplied to the focus driving coil 12, the lens bobbin 8 is affected by a magnetic field formed by the magnetic circuit, and as shown by an arrow F in FIG. The moving operation is performed in the axial direction of the support shaft 15, that is, in the focus direction (the optical axis direction of the objective lenses 7a and 7b).

  Further, in this biaxial actuator, when a drive current is supplied to the tracking drive coils 13 and 13, the lens bobbin 8 receives an action from the magnetic field formed by the magnetic circuit, and is indicated by an arrow T in FIG. As described above, the objective lens 7a, 7b is rotated about the axis of the support shaft 15 and moved in the tracking direction (direction orthogonal to the optical axis of the objective lens 7a, 7b).

That is, the biaxial actuator 19 is supplied with a focus drive current based on the focus error signal to the focus drive coil 12, and moves the objective lenses 7a and 7b following the surface shake of the optical discs 101 and 102. Manipulate. The biaxial actuator 19 is supplied with a tracking drive current based on the tracking error signal to the tracking drive coils 13 and 13 so that the objective lenses 7a and 7b are eccentric to the recording tracks of the optical disks 101 and 102. Follow and move.
[8] Other forms of the configuration of the biaxial actuator (3)
In the optical pickup according to the present invention, the biaxial actuator 19 may be configured such that the lens bobbin 8 is movably supported by a plate spring 49 as shown in FIGS.

  Similarly to the biaxial actuator described above, this biaxial actuator 19 also moves the first and second objective lenses 7a and 7b in the direction of the optical axis of each objective lens 7a and 7b, that is, by the arrow F in FIG. It is supported so as to be movable in the focus direction shown and the direction orthogonal to the optical axis, that is, the tracking direction shown by the arrow T in FIG. As shown in FIGS. 15 and 16, the objective lenses 7 a and 7 b are used to record signals on the optical disks 101 and 102 mounted on the disk table 25 by mounting the optical pickup 19 on the optical block 17. The optical system block 17 is moved along the guide shaft 23 and the support shaft 24 and moved along the inner and outer peripheries of the optical disks 101 and 102. The first and second objective lenses 7 a and 7 b are arranged in a direction substantially orthogonal to the longitudinal direction of the guide shaft 23, that is, in the circumferential direction of the optical disks 101 and 102 mounted on the disk table 25. Yes.

  As shown in FIGS. 17 and 18, the biaxial actuator 19 has a substantially rectangular lens bobbin 8 serving as a movable portion to which the objective lenses 7 a and 7 b are attached. The objective lenses 7a and 7b have optical axes parallel to each other. The lens bobbin 8 is fixed to a fixed block 50 disposed on the base plate 16 on the rear side of the lens bobbin 8 by four parallel plate springs 49, 49, 49, 49. , And is movably attached in the focus direction and the tracking direction. That is, each of the leaf springs 49 is attached to the fixed block 50 on the base end side, and two on the distal end side corresponding to the spring attaching portions 51 and 51 provided on both sides of the lens bobbin 8. Yes. Each of the leaf springs 49 is curved and displaced, thereby moving the lens bobbin 8 in the focusing direction indicated by the arrow F in FIG. 16 and the tracking direction indicated by the arrow T in FIG.

  The lens bobbin 8 is provided with a focus drive coil 12 and tracking drive coils 13 and 13, which are drive coils. The focus drive coil 12 is wound around the outer peripheral surface of the lens bobbin 8 with the winding axis direction as the optical axis direction of the objective lenses 7a and 7b. The tracking drive coils 13 and 13 are paired on the front end surface and the rear end surface of the lens bobbin 8 so that the winding axis directions are parallel to each other and are orthogonal to the optical axes of the objective lenses 7a and 7b. Installed.

  The biaxial actuator 19 has a magnetic circuit that positions the drive coils 12, 13, and 13 in a magnetic field. The magnetic circuit includes a pair of yokes 9, 9 erected on the base plate 16 in front of and behind the lens bobbin 8, and a pair of magnets 10 a attached corresponding to the yokes 9, 9. , 10a. Each of the yokes 9 and 9 is formed integrally with the base plate 16 by bending a part of the base plate 16 made of a magnetic material upward. The main surface portion facing the side faces the front end surface and the rear end surface of the lens bobbin 8.

  The magnets 10a, 10a are attached to the inner side surfaces of the yokes 9, 9. These magnets 10a and 10a are each single-sided magnetized, with one magnetic pole facing the front and rear portions of the focus drive coil 12 and the tracking drive coils 13 and 13, respectively. The focus drive coil 12 and the tracking drive coils 13 and 13 are positioned in a magnetic field generated from a magnetic pole.

  The magnetic field formed by the magnets 10 a and 10 a attached to the yokes 9 and 9 is a linear magnetic field that crosses the focus driving coil 12 and the tracking driving coils 13 and 13 in the front-rear direction of the lens bobbin 8.

  In this biaxial actuator 19, when a driving current is supplied to the focus driving coil 12, the lens bobbin 8 is affected by the magnetic field formed by the magnetic circuit, and as shown by an arrow F in FIG. The moving operation is performed in the focusing direction, that is, in the optical axis direction of the objective lenses 7a and 7b. In this biaxial actuator, when a drive current is supplied to the tracking drive coils 13 and 13, the lens bobbin 8 is acted on by a magnetic field formed by the magnetic circuit, and is indicated by an arrow T in FIG. Thus, the moving operation is performed in the tracking direction, that is, the direction orthogonal to the optical axis of the objective lenses 7a and 7b.

  That is, the biaxial actuator 19 is supplied with a focus drive current based on the focus error signal to the focus drive coil 12, and moves the objective lenses 7a and 7b following the surface shake of the optical discs 101 and 102. Manipulate. The biaxial actuator 19 is supplied with a tracking drive current based on the tracking error signal to the tracking drive coils 13 and 13 so that the objective lenses 7a and 7b are eccentric to the recording tracks of the optical disks 101 and 102. Follow and move.

  The optical pickup has a small margin for the angle between the tracking direction of one of the first and second objective lenses 7a and 7b and the normal of the recording track at the position where the objective lens faces. That is, if the tracking error signal cannot be accurately detected when the angle between the tracking direction and the normal line increases, the one objective lens is moved to the optical disc 101 when the optical system block 17 is moved. , 102, and the other objective lens may be moved on a straight line separated by a certain distance from the centers of the optical discs 101, 102.

  The case where there is little margin in the angle between the tracking direction and the normal line of the recording track at the position where the objective lens faces is the case where the tracking error signal is detected by the so-called three beam method, for example. The case where there is a margin in the angle between the tracking direction and the normal line of the recording track at the position where the objective lens is opposed, for example, when the tracking error signal is detected by the so-called push-pull method of the one beam method It is.

  For example, this optical pickup has a margin for the angle between the first tracking direction of the first objective lens 7a and the normal line of the recording track at the position where the first objective lens 7a faces. As shown in FIG. 22, the second objective lens 7b is moved and operated while maintaining the opposition to the straight line R passing through the centers of the optical discs 101 and 102 and parallel to the moving direction of the optical system block 17. And the first objective lens 7a is moved and operated in parallel with the second objective lens 7b in a state where the first objective lens 7a is kept facing a straight line with a certain distance from the centers of the optical discs 101 and 102. As good as

  In this case, in the biaxial actuator 19, the first tracking direction, which is the moving operation direction of the first objective lens 7a, and the recording track at the position where the first objective lens 7a faces each other. The angle formed with the tangent line is not 90 °. That is, in the biaxial actuator 19, the first tracking direction and the normal line of the recording track at the position where the first objective lens 7a faces each other form an angle.

  Further, in the case where there is a margin for the angle between the second tracking direction of the second objective lens 7b and the normal line of the recording track at the position where the second objective lens 7b faces, it is shown in FIG. As described above, the first objective lens 7a is moved and operated while maintaining the opposition to the straight line R passing through the centers of the optical discs 101 and 102 and parallel to the moving direction of the optical system block 17. The objective lens 7b may be moved and operated in parallel to the first objective lens 7a in a state in which the objective lens 7b is kept facing a straight line with a certain distance from the centers of the optical discs 101 and 102.

  In this case, in the biaxial actuator 19, the second tracking direction which is the moving operation direction of the second objective lens 7b and the recording track at the position where the second objective lens 7b is opposed. The angle formed with the tangent line is not 90 °. That is, in the biaxial actuator 19, the second tracking direction and the normal line of the recording track at the position where the second objective lens 7b faces each other form an angle.

FIG. 1 is a perspective view showing a configuration of an optical pickup according to the present invention. FIG. 2 is a longitudinal sectional view showing the configuration of the optical pickup. FIG. 3 is a plan view showing the configuration of the optical pickup. FIG. 4 is a perspective view showing a configuration of an optical system in the optical pickup. FIG. 5 is a longitudinal sectional view showing a configuration of a laser coupler (light emitting / receiving composite element) used in the optical pickup. FIG. 6 is a perspective view showing a configuration of a biaxial actuator which is a main part of the optical pickup. FIG. 7 is an exploded perspective view showing a configuration of a biaxial actuator which is a main part of the optical pickup. FIG. 8 is a block diagram showing the configuration of the disc player according to the present invention. FIG. 9 is a perspective view showing another example of the configuration of the biaxial actuator. FIG. 10 is an exploded perspective view showing the configuration of the biaxial actuator shown in FIG. FIG. 11 is a plan view showing the configuration of the biaxial actuator shown in FIG. 12 is a side view showing the configuration of the biaxial actuator shown in FIG. FIG. 13 is a perspective view showing another example of the optical pickup according to the present invention. FIG. 14 is an exploded perspective view showing the configuration of the biaxial actuator shown in FIG. FIG. 15 is a perspective view showing still another example of the configuration of the optical pickup according to the present invention. FIG. 16 is a longitudinal sectional view showing the configuration of the optical pickup shown in FIG. FIG. 17 is a perspective view showing a configuration of a biaxial actuator which is a main part of the optical pickup shown in FIG. FIG. 18 is a perspective view showing a configuration of a movable part that is a main part of the biaxial actuator shown in FIG. FIG. 19 is a plan view showing the configuration of the biaxial actuator shown in FIG. FIG. 20 is a side view schematically showing the internal configuration of the optical pickup with a part thereof broken. FIG. 21 is a block diagram showing a configuration of a disc player according to the present invention. FIG. 22 is a plan view showing the positional relationship between the optical pickup and the disk-shaped optical recording medium in the disk player, and one objective lens being on the radial line of the disk-shaped optical recording medium. FIG. 23 is a plan view showing the positional relationship between the optical pickup and the disc-shaped optical recording medium in the disc player and the other objective lens being on the radial line of the disc-shaped optical recording medium. FIG. 24 is a plan view showing another example of the configuration of the optical pickup. FIG. 25 is a plan view showing the optical pickup shown in FIG. FIG. 26 is a plan view schematically showing still another example of the configuration of the optical pickup. FIG. 27 is a perspective view showing a configuration of a conventional optical pickup.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 1st semiconductor laser, 1a 2nd semiconductor laser, 5 1st photodetector, 5a 2nd photodetector, 7a 1st objective lens, 7b 2nd objective lens, 8 Lens bobbin, 19 2 Axis actuator, 101 1st type optical disc, 102 2nd type optical disc

Claims (7)

Optical axes of the first and second objective lenses these objective lenses each corresponding thickness of the substrate which transmits light with provided on the incident surface side of the light beam to a plurality of types of disk-shaped optical recording medium having different respective Are mounted in parallel with each other and are moved in a focusing direction parallel to the optical axis of each objective lens and in a tracking direction orthogonal to the optical axis of each objective lens, and orthogonal to the optical axis of the movable section. A fixed portion disposed at a distance in a plane, and a proximal end side attached to the fixed portion and a distal end side attached to the movable portion, and the movable portion is supported to be movable in the focus direction and the tracking direction. more and an elastic support member, is moved respective objective lens by moving operating the movable portion in the focusing direction and the tracking direction And a two-axis actuator that,
A first light source for causing a light beam to enter the first objective lens via a first optical path;
A second light source for making a light beam incident on the second objective lens through a second optical path,
The light beam emitted from the first light source is irradiated by the first objective lens substantially perpendicularly to the signal recording layer of the disc-shaped optical recording medium and condensed on the signal recording layer, or the first The light beam emitted from the light source 2 is irradiated onto the signal recording layer of the disk-shaped optical recording medium substantially perpendicularly by the second objective lens and condensed on the signal recording layer, and the disk-shaped optical In an optical pickup that writes or reads information signals to or from a recording medium,
The first light source and the second light source have different emission wavelengths,
The numerical aperture of the first objective lens is larger than the numerical aperture of the second objective lens,
When the optical system block that supports the biaxial actuator is moved and moved relative to the central portion of the disc-shaped optical recording medium, the objective of one of the first and second objective lenses is The lens moves through the center of the disk-shaped optical recording medium while facing the straight line parallel to the relative movement direction of the optical system block and the disk-shaped optical recording medium. Moved in a state of being arranged in a direction orthogonal to the relative movement direction with respect to the objective lens,
Using one objective lens that moves in a state of being opposed to a straight line parallel to the relative movement direction through the center of the disc-shaped optical recording medium, the disc-shaped optical recording medium corresponding to the one objective lens is used. The tracking error when the information signal is written or read is detected by the three beam method,
When the one objective lens is used to detect a tracking error when the information signal is written to or read from the disk-shaped optical recording medium corresponding to the other objective lens, using the other objective lens. optical pickup for by a method different from the method of detecting a tracking error. The emission wavelength of the first light source is the 635nm to 650 nm, the second optical pickup emission wavelength of the light source according to claim 1, wherein Ru 780nm der. The numerical aperture of the first objective lens is 0.6, the second claim 1 optical pickup according the numerical aperture of the objective lens is Ru der 0.45. The movable portion of the biaxial actuator is movable when the plurality of elastic support members are bent and displaced , and a drive coil is attached, and the drive coil is positioned in a magnetic field formed by a magnetic circuit. the optical pickup of claim 1, wherein that will be moving operation by supplying a drive current to the drive coil. Recording medium holding for holding a plurality of types of disc-shaped optical recording media provided on the light incident surface side and having a transparent substrate having a light transmission property and a signal recording layer, each of which has a different thickness. Mechanism,
Respective attached with the first and second objective lenses respectively corresponding to each of differing plurality of types of disk-shaped optical recording medium the thickness of the transparent substrate has a mutually parallel optical axes of the objective lens objective A movable part that is moved in a focusing direction parallel to the optical axis of the lens and a tracking direction that is orthogonal to the optical axis of each objective lens, and a plane that is orthogonal to the optical axis of the movable part are disposed with a space therebetween. And a plurality of elastic support members that have a proximal end attached to the fixed portion and a distal end attached to the movable portion and support the movable portion movably in the focus direction and the tracking direction. A biaxial actuator that moves each objective lens in the focus direction and the tracking direction by moving the movable part; and
A first light source for causing a light beam to enter the first objective lens via a first optical path;
A second light source for making a light beam incident on the second objective lens through a second optical path,
The light beam emitted from the first light source is irradiated by the first objective lens substantially perpendicularly to the signal recording layer of the disc-shaped optical recording medium and condensed on the signal recording layer, or the first The light beam emitted from the light source 2 is irradiated onto the signal recording layer of the disk-shaped optical recording medium substantially perpendicularly by the second objective lens and condensed on the signal recording layer, and the disk-shaped optical In a disc player that writes or reads information signals to or from a recording medium,
The first light source and the second light source have different emission wavelengths,
The numerical aperture of the first objective lens is larger than the numerical aperture of the second objective lens,
When the optical system block that supports the biaxial actuator is moved and moved relative to the central portion of the disc-shaped optical recording medium, the objective of one of the first and second objective lenses is The lens moves through the center of the disk-shaped optical recording medium while facing the straight line parallel to the relative movement direction of the optical system block and the disk-shaped optical recording medium. Moved in a state of being arranged in a direction orthogonal to the relative movement direction with respect to the objective lens,
Using one objective lens that moves through the center of the disk-shaped optical recording medium and faces the straight line parallel to the relative movement direction, the disk-shaped optical recording medium corresponding to the one objective lens is used. The tracking error when the information signal is written or read is detected by the three beam method,
When the one objective lens is used to detect a tracking error when the information signal is written to or read from the disk-shaped optical recording medium corresponding to the other objective lens, using the other objective lens. disc player carried out by a method different from the method of detecting a tracking error. An optical system block that supports the biaxial actuator and is capable of relative movement with respect to the disc-shaped optical recording medium in a direction of contact with and away from the center of the disc-shaped optical recording medium;
When the optical system block is moved relative to the central portion of the disk-shaped optical recording medium, the first objective lens passes through the center of the disk-shaped optical recording medium and the optical system block and the disk-shaped optical medium. Moved in a state of being opposed to a straight line parallel to the direction of relative movement with the recording medium,
On the first optical path, there is disposed an optical diffraction element that splits an incident light beam into zero-order light and at least ± first-order light,
Based on the light amount difference of the reflected light beam from the disk-shaped optical recording medium of the ± first-order light, the focusing point of the zero-order light by the first objective lens, the recording track on the disk-shaped optical recording medium, disk player of the resulting Ru claim 5, wherein a tracking error signal indicating a deviation amount in the radial direction of the disk-shaped optical recording medium. The emission wavelength of the first light source is 635nm to 650 nm, the second light source disc player according to claim 6, wherein the emission wavelength Ru 780nm der of.

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