JP2009245476A - Objective lens actuator and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an objective lens actuator capable of accurately correcting, in simple configuration, tilting caused by warping or wobbling of surface of an optical disk, and an optical disk device using the same. <P>SOLUTION: An objective lens actuator comprises: a radial tilt magnet placed tubularly around a radial tilt axis of a lens holder at a terminal portion of a lens holder opposite to an objective lens; and a pair of radial tilt coils fixed at a fixed portion and arranged with the radial tilt magnet therebetween for rotationally driving the lens holder around the radial tilt axis, wherein the objective lens is tilted by rotating the radial tilt magnet with a couple of electromagnetic forces, thereby performing tilt correction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an objective lens actuator and an optical disc apparatus, and more particularly to an objective lens actuator that drives an objective lens of an optical pickup in three axes and an optical disc apparatus incorporating the objective lens actuator.

  A plurality of types of recording density optical disks called CD (Compact Disc) standards and DVD (Digital Versatile Disk) standards are already widely used. In recent years, by recording information using laser light of a blue-violet wavelength, Furthermore, BD (Blu-ray Disc) and HD DVD (High Definition Digital Versatile Disk), which are ultra-high density optical discs with higher recording density, have been put into practical use.

  An optical disc apparatus that reproduces information on an optical disc or records information on an optical disc reproduces and records information by accurately focusing a laser beam on a specific information recording surface on the optical disc. This alignment is realized by controlling the relative position or relative attitude angle between the objective lens for condensing the laser beam and the optical disk using an objective lens actuator.

  Specifically, position control called tracking control and focus control and attitude angle control called radial tilt control are performed using servo mechanisms.

  Tracking control is servo control that finely adjusts the position of the objective lens in the radial direction so that the focal point of the laser beam is always located at the center of a specific track of the optical disk. The focus control is servo control for controlling the separation distance between the objective lens and the optical disc so that the focal point of the laser beam is accurately positioned on the optical disc.

  With radial tilt control, even when the reflecting surface of the optical disc is slightly displaced from the plane perpendicular to the optical axis of the laser beam and tilted in the radial direction, the laser beam is always irradiated perpendicularly to the reflecting surface of the optical disc. In addition, the servo control is for controlling the attitude angle of the objective lens in the radial direction (radial direction) of the optical disk.

  In general, the servo control is driven by electromagnetic force generated by a coil current and a permanent magnet magnetic flux. For this reason, the movable part to which the objective lens is mounted and the fixed part that supports the movable part are appropriately arranged so that the coil and the permanent magnet are adjacent to each other.

  In ultra-high-density optical disks with increased recording density, coma aberration caused by the tilt of the optical axis of the objective lens and the recording surface of the optical disk reduces the signal quality of recording and playback, so the accuracy of radial tilt control is an important issue It has become. Patent Document 1 proposes an objective lens actuator provided with a radial tilt correction mechanism using two tilt correction coils and two tilt correction magnets.

FIG. 8 shows a conventional objective lens actuator. In this objective lens actuator 400, the two tilt correction coils 401 apply forces in opposite directions to the two tilt correction magnets 403 provided across the rotation center of the lens holder 402, and twist the lens holder 402 in the tilt direction. It is configured. Thereby, the lens holder 402 holding the tilt correction magnet 403 can be rotated in the tilt direction, and the light irradiation angle can be adjusted by tilting the optical axis of the objective lens 404.
JP 2004-310966 A

  In the radial tilt correction mechanism provided with the two tilt correction coils 401 and the two tilt correction magnets 403 in FIG. 8, the two tilt correction coils 401 and the two tilt correction magnets 403 are accurately attached to the lens holder. Cost. The two tilt correction magnets 403 are arranged with the rotation center of the lens holder 402 interposed therebetween. However, when the mounting position is shifted, an imbalance occurs with respect to the rotation center.

  When an imbalance occurs with respect to the center of rotation, it becomes difficult to accurately follow the tilt of the objective lens with respect to the tilt of the information recording surface of the optical disc. In order to ensure the basic function and performance of the tilt correction of the objective lens actuator, it is desired that the tilt correction coil and the tilt correction magnet be easily and accurately assembled. Also, if the orientations of the magnetic poles of the two tilt correction magnets 403 are reversed, the magnetic poles of the two tilt correction magnets 403 need to be assembled with great care.

  The present invention has been made in view of the above circumstances, and in an objective lens actuator, an objective lens actuator capable of accurately correcting a tilt generated by warpage or surface wobbling of an optical disc with a simple configuration, and an optical disc apparatus using the objective lens actuator The purpose is to provide.

  To achieve the above object, the objective lens actuator of the present invention is an objective lens actuator capable of translational drive in the tracking direction, translational drive in the focus direction, and rotational drive around the radial tilt axis. An objective lens for condensing the laser beam, an objective lens at the end, a focus coil for translationally driving the objective lens in the focus direction at the center, and the objective lens on the side surface of the focus coil in the tracking direction A lens holder having a pair of tracking coils that are driven in translation, and a radial tilt magnet disposed in a cylindrical shape around a radial tilt axis of the lens holder at the end of the lens holder opposite to the objective lens And a trackin disposed at a position facing the tracking coil A magnet, a focus magnet disposed at a position facing the focus coil, a fixed portion to which the tracking magnet and the focus magnet are fixed, and fixed to the fixed portion, with the radial tilt magnet interposed therebetween A pair of radial tilt coils that are arranged and rotationally drive the lens holder about a radial tilt axis, and a suspension in which one end is fixed to the fixing portion, the other end is fixed to the lens holder, and the lens holder is held hollow. And a wire.

  The optical disc apparatus of the present invention modulates an optical pickup provided with an objective lens actuator, a drive control unit for controlling driving of the objective lens actuator, and recording data, and outputs the data as a laser control signal to the optical pickup. An objective lens actuator capable of translational drive in the tracking direction, translational drive in the focus direction, and rotational drive about a radial tilt axis, on the information recording surface of the optical disc. An objective lens for condensing the laser beam, an objective lens at the end, a focus coil for translationally driving the objective lens in the focus direction at the center, and the objective lens on the side surface of the focus coil in the tracking direction Lens phone having a pair of tracking coils for translational driving A radial tilt magnet disposed in a cylindrical shape around a radial tilt axis of the lens holder at the end of the lens holder opposite to the objective lens, and disposed at a position facing the tracking coil. Tracking magnet, a focusing magnet disposed at a position facing the focusing coil, a fixing part to which the tracking magnet and the focusing magnet are fixed, and a fixing part to which the radial tilt magnet is interposed. A pair of radial tilt coils disposed between and rotating the lens holder about a radial tilt axis, one end fixed to the fixing portion, the other end fixed to the lens holder, and the lens holder being hollow And a suspension wire to be held.

  According to the objective lens actuator and the optical disc apparatus according to the present invention, it is possible to accurately correct a tilt generated by warpage or surface deflection of the optical disc with a simple configuration, and to reproduce and record information on the optical disc with high reliability. Is possible.

  Embodiments of an objective lens actuator and an optical disc apparatus according to the present invention will be described with reference to the drawings.

  The optical disc apparatus 100 according to the present embodiment includes, for example, a CD (Compact Disk) -ROM (Read Only Memory), a CD-R (Recordable), a CD-RW (Rewritable), a DVD (Digital Versatile Disk) -ROM, and a DVD- Information is recorded / reproduced on / from an optical disc 200 such as R, DVD-RW, DVD-RAM (Random Access Memory) and BD (Blu-ray Disc).

  FIG. 1 is a block diagram showing a configuration example of an optical disc apparatus 100 according to the present invention. The optical disc apparatus 100 includes an optical pickup 50, a triaxial control unit 60 (drive control unit), a reproduction processing unit 70, and a recording processing unit 80.

  The optical pickup 50 irradiates the optical disc 200 with laser light for information recording and reproduction, converts the reflected light from the optical disc 200 into an electrical signal, and outputs it as a reproduction signal. As a semiconductor laser 51, a collimating lens 52, a PBS (polarizing beam splitter) 53, a diffraction grating and quarter-wave plate 56, the objective lens 11, a condenser lens 54, and a photodetector 55. A rising mirror 57 that changes the direction of the laser beam is provided between the PBS 53 and the diffraction grating and quarter-wave plate 56. A configuration in which the rising mirror 57 is not used may be employed.

  The optical pickup 50 also includes an objective lens actuator 10 to which the objective lens 11 and the diffraction grating / quarter wavelength plate 56 are attached. The objective lens 11, the diffraction grating and the quarter wavelength plate 56 are mounted by the objective lens actuator 10. Is controlled in three axes. The triaxial control unit 60 includes a focus error signal generation circuit 61, a focus control circuit 62, a tracking error signal generation circuit 63, a tracking control circuit 64, a radial tilt error signal generation circuit 65, and a radial tilt control circuit 66.

  Control signals generated by these circuits included in the three-axis control unit 60 are output to the objective lens actuator 10 to perform position control and posture angle control of the objective lens 11. Specifically, focus control for controlling the separation distance between the objective lens and the optical disc so that the focal point of the laser beam is accurately positioned on the optical disc, and the focal point of the laser beam always at the center of a specific track of the optical disc. Tracking control to finely adjust the radial position of the objective lens, and even if the reflecting surface of the optical disk is slightly displaced from the plane perpendicular to the optical axis of the laser beam and tilted in the radial direction, the laser beam is reflected on the reflecting surface of the optical disk. Servo-controlled radial tilt control for controlling the attitude angle of the objective lens in the radial direction of the optical disc is performed so as to always irradiate vertically with respect to the optical disc.

  The reproduction processing unit 70 performs reproduction processing on the signal output from the optical pickup 50, and includes a signal processing circuit 71 and a demodulation circuit 72. The recording processing unit 80 mainly records information on the optical disc 200, and includes a modulation circuit 81, a recording / reproduction control unit 82, and a laser control circuit 83.

  The operation of the optical disc apparatus 100 configured as described above will be described. First, the operation of recording information on the optical disc 200 will be described. The modulation circuit 81 of the recording processing unit 80 modulates recording information (data symbols) provided from a host, for example, a personal computer main body into a channel bit sequence based on a predetermined modulation method. The channel bit sequence corresponding to the recording information is input to the recording / reproducing control unit 82.

  The recording / reproducing control unit 82 receives a recording / reproducing instruction (in this case, a recording instruction) from the host. The recording / reproducing control unit 82 outputs a control signal to the triaxial control unit 60, and drives the objective lens actuator 10 so that the light beam is appropriately condensed at the target recording position. Further, the recording / reproducing control unit 82 supplies the channel bit sequence to the laser control circuit 83.

  The laser control circuit 83 converts the channel bit series into a laser driving waveform and drives the semiconductor laser 51 in pulses. As a result, the semiconductor laser 51 generates a recording light beam corresponding to a desired bit sequence. The recording light beam generated by the semiconductor laser 51 is converted into parallel light by the collimator lens 52, enters the PBS 53, and is transmitted therethrough. The light beam that has passed through the PBS 53 passes through the diffraction grating and the quarter-wave plate 56 and is focused on the information recording surface of the optical disc 200 by the objective lens 11.

  The focused light beam for recording can obtain the best light beam spot on the information recording surface of the optical disc 200 by focus control, tracking control, and radial tilt control by the triaxial control unit 60 and the objective lens actuator 10. Maintained in a state.

  Next, the reproduction of information from the optical disc 200 by the optical disc apparatus 100 will be described. The recording / reproducing control unit 82 receives a recording / reproducing instruction (in this case, a reproducing instruction) from the host. The recording / reproduction control unit 82 outputs a reproduction control signal to the laser control circuit 83 in accordance with a reproduction instruction from the host.

  The laser control circuit 83 drives the semiconductor laser 51 based on the reproduction control signal and generates a reproduction light beam. The reproduction light beam generated by the semiconductor laser 51 is converted into parallel light by the collimator lens 52, and enters and passes through the PBS 53. The light beam that has passed through the PBS 53 passes through the diffraction grating and the quarter-wave plate 56 and is focused on the information recording surface of the optical disc 200 by the objective lens 11.

  The condensed light beam for reproduction can obtain the best light beam spot on the information recording surface of the optical disc 200 by focus control, tracking control, and radial tilt control by the triaxial control unit 60 and the objective lens actuator 10. Maintained in a state.

  The reproduction light beam irradiated on the optical disc 200 is reflected by the reflective film or reflective recording film in the information recording surface. The reflected light passes through the objective lens 11 in the reverse direction to become parallel light again, passes through the diffraction grating and the quarter-wave plate 56, and then is reflected by the PBS 53 having a polarization perpendicular to the incident light.

  The light beam reflected by the PBS 53 becomes convergent light by the condenser lens 54 and enters the photodetector 55. The photodetector 55 is composed of, for example, a four-divided photodetector. The light beam incident on the photodetector 55 is photoelectrically converted into an electric signal and amplified. The amplified signal is equalized in the signal processing circuit 71 of the reproduction processing unit 70, binarized, and sent to the demodulation circuit 72. The demodulation circuit 72 performs a demodulation operation corresponding to a predetermined modulation method and outputs reproduced data.

  On the other hand, part of the electrical signal output from the photodetector 55 is input to the triaxial control unit 60, and a focus error signal generation circuit 61 generates a focus error signal. Similarly, part of the electrical signal output from the photodetector 55 is input to the three-axis controller 60, and a tracking error signal and a radial tilt error signal are generated by the tracking error signal generation circuit 63 and the radial tilt error circuit 66, respectively. Is done.

  The focus control circuit 62 controls the objective lens actuator 10 based on the focus error signal and controls the focus of the beam spot. The tracking control circuit 64 controls the objective lens actuator 10 based on the tracking error signal, and controls tracking of the beam spot. The radial tilt control circuit 66 controls the objective lens actuator 10 based on the radial tilt error signal and controls the radial tilt of the beam spot.

  As described above, the objective lens actuator 10 controls the position and attitude angle of the objective lens 11 mounted on the objective lens actuator 10 based on the control signal from the triaxial control unit 60, and the position of the beam spot with respect to the optical disc 200. Is maintained to be optimal.

  Next, the structure and operation of the first embodiment of the objective lens actuator 10 will be described. 2, 3, and 4 are external views showing the overall structure of the objective lens actuator 10. FIG. 2 is a plan view of the objective lens actuator 10 as seen from the optical disk side. FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2, and is a view of the objective lens actuator 10 as viewed from the side. 4 is a cross-sectional view taken along the line BB in FIG. 2, and is a side view of the objective lens actuator 10 as seen from a direction different from that in FIG.

  The objective lens actuator 10 includes a movable part 34 including a lens holder 33 that holds the objective lens 11, with respect to the information recording surface of the optical disc 200, translated in the focus direction, translated in the tracking direction, and a radial tilt shaft 40. Each has a function of independently performing rotational driving around (in the radial tilt direction).

  As shown in FIG. 2, the fixed portion 30 that supports the movable portion 34 includes a yoke base 35, a gel holder 36 that is disposed on the rear side of the yoke base 35 and has a substantially rectangular parallelepiped shape, and a fixed end that is fixed on the further rear side of the gel holder 36. The circuit board 37 is used. In FIG. 2, the yoke base 35 formed in a flat plate shape is installed so as to be parallel to the information recording surface of the optical disc 200.

  The gel holder 36 has openings 36a and 36b formed on both sides thereof. The opening 36a is filled with a gel agent for giving damping to the two suspension wires 38a and 38b. In the opening 36b, the three suspension wires 39a and 39b are damped. Filled with gel to give. A fixed end circuit board 37 is attached to the rear of the gel holder 36. The fixed end circuit board 37 is connected to output terminals of a focus control circuit 62, a tracking control circuit 64, and a radial tilt control circuit 66 constituting the triaxial control unit 60, respectively.

  On the fixed end circuit board 37, one end portions of two suspension wires 38a and 38b, which are elastic linear bodies, are fixed in a line in the focus direction at a position corresponding to the opening 36a of the gel holder 36. . These suspension wires 38a and 38b are made of a conductive material, and the other end penetrates through the opening 36a of the gel holder 36 and reaches almost the center of the yoke base 35, and is fixed to the movable part 34. .

  Further, one end portions of two suspension wires 39a and 39b are fixed to the fixed-end circuit board 37 in a line in the focus direction at a position corresponding to the opening 36b of the gel holder 36. These suspension wires 39a and 39b are made of a conductive material, and the other end portions pass through the opening 36b of the gel holder 36, reach the substantially central portion of the yoke base 35, and are fixed to the movable portion 34. .

  The movable portion 34 is supported between the other end portions of the two suspension wires 38a and 38b and the other end portions of the two suspension wires 39a and 39b. A lens holder 33 holding the objective lens 11 is attached to the movable part 34. In addition, a diffraction grating and a quarter-wave plate 56 are disposed inside the lens holder 33.

  The other ends of the suspension wires 38 a and 38 b are connected to the lens holder 33. Similarly, the other ends of the suspension wires 39 a and 39 b are connected to the lens holder 33. With these connections, the movable portion 34 is elastically supported in a hollow manner with respect to the fixed portion 30, so that translational movement in the tracking direction and focus direction and rotation around the radial tilt axis 40 are possible.

  The openings 36a and 36b of the gel holder 36 are filled with a viscoelastic material such as a silicone gel, for example, so that the suspension wires 38a and 38b and 39a and 39b have high damping characteristics. Yes.

  A pair of tracking coils 41 a and 41 b and a focus coil 42 are provided at the center of the lens holder 33. The focus coil 42 has three side surfaces bonded and fixed to the inside of the central window portion of the lens holder. The tracking coils 41a and 41b are bonded and fixed to the other one side surface of the focus coil 42 that is not bonded to the lens holder 33.

  The coils 41a, 41b, 42 of the operating unit 34 are electrically connected to the suspension wires 38a, 38b, 39a, 39b (not shown), and the control current output from the triaxial control unit 60 is fixed. The coils 41a, 41b and 42 are supplied via the end circuit board 37 and the suspension wires 38a and 38b and 39a and 39b.

  A tracking magnet 44 and a focus magnet 45 are arranged and fixed on the yoke base 35 so as to sandwich the tracking coils 41a, 41b and the focus coil 42 with predetermined intervals from the tracking coils 41a and 41b and the focus coil 42, respectively. ing. Yokes 35a and 35b are provided for fixing the tracking magnet 44 and the focus magnet 45 in the direction of the optical disk side substantially perpendicularly from the yoke base 35 to form a magnetic circuit.

  When a current is supplied to the focus coil 42 configured as described above, an electromagnetic force in the focus direction acts on the focus coil 42. By this electromagnetic force, the objective lens 11 mounted on the movable portion 34 is driven to translate in the focus direction. Similarly, in the translational drive in the tracking direction, when a current is supplied to the tracking coils 41a and 41b, an electromagnetic force in the tracking direction acts on the tracking coils 41a and 41b. By this electromagnetic force, the objective lens 11 mounted on the movable portion 34 is driven to translate in the tracking direction. The translation operation in the focus direction and the translation operation in the tracking direction are controlled based on a control signal from the triaxial control unit 60.

  A cylindrical radial tilt magnet 46 is disposed at the end of the lens holder 33 opposite to the objective lens 11. The lens holder 33 has a radial tilt rotation shaft 40 of the operating portion 34 at its center, protrudes from the side surface of the lens holder 33 in the radial tilt shaft 40 direction, and is fixed to the lens holder 33 integrally. Is provided. The radial tilt magnet 46 is fixed by bonding or the like so that the inner diameter of the radial tilt magnet 46 and the outer diameter of the shaft 47 are substantially fitted. Accordingly, the radial tilt magnet 46 is arranged in a cylindrical shape around the radial tilt axis of the operating portion 34.

  Radial tilt coils 43a and 43b are arranged so as to sandwich the radial tilt magnet 46 in the focus direction. The radial tilt coils 43a and 43b are fixed to the opening at the center of the gel holder 36, and yokes 48a and 48b constituting a magnetic circuit with the radial tilt magnet 46 are arranged inside the coils.

  FIG. 5 is a diagram illustrating the positional relationship between the radial tilt magnet 46 and the radial tilt coils 43a and 43b disposed at positions facing the radial tilt magnet 46, including the polarity of the magnet. The radial tilt magnet 46 has a cylindrical shape and is magnetized so that the inside is an S pole and the outside is an N pole. As a result, a magnetic flux is formed from the radial tilt magnet 46 toward the radial tilt coils 43a and 43b.

  In FIG. 5, when a current is passed through the coil portion of the radial tilt coil 43a close to the radial tilt magnet 46 in the direction perpendicular to the paper surface, a force F1 in the direction of the arrow is generated by the electromagnetic force. Similarly, when a current is passed vertically upward through the coil portion of the radial tilt coil 43b close to the radial tilt magnet 46, a force F2 in the direction of the arrow is generated. A couple of forces is generated around the radial tilt shaft 40 by the forces F1 and F2, and the radial tilt magnet 46 rotates counterclockwise. Accordingly, the lens holder 33 also rotates counterclockwise around the radial tilt axis 40.

  Even if the radial tilt magnet 46 moves slightly between the radial tilt coils 43a and 43b, the magnitude of the couple hardly changes. Accordingly, the lens holder, that is, the objective lens can be stably tilted in the radial tilt direction with respect to the yoke base.

  As described above, the radial tilt magnet 46 disposed in the cylindrical shape around the radial tilt axis 40 of the lens holder at the end opposite to the objective lens of the lens holder, and the radial tilt magnet 46 fixed to the fixing portion 30. The radial tilt can be corrected by the pair of radial tilt coils 43a and 43b which are arranged with the lens holder 33 interposed therebetween and which rotationally drive the lens holder 33 around the radial tilt axis 40. The rotation around the radial tilt axis 40 is controlled based on a control signal from the triaxial control unit 60.

  The radial tilt magnet 46 has a cylindrical shape and can be assembled without making a mistake in the direction of magnetization because the radial tilt magnet 46 may be fitted into the shaft 47 of the lens holder 33. Therefore, stable quality can be secured in the assembly of the objective lens actuator 10, and the radial tilt can be corrected with high accuracy.

  6 and 7 are external views of an objective lens actuator 300 according to the second embodiment of the present invention. FIG. 6 is a plan view of the objective lens actuator 300 as viewed from the optical disk side. FIG. 7 is a cross-sectional view taken along the CC line in FIG. 6 and shows the objective lens actuator 300 as viewed from the side.

  The second embodiment is different from the first embodiment in that the radial tilt coils 43a and 43b in the first embodiment are replaced with the radial tilt coils 301a and 301b, and the arrangement of the radial tilt coils is changed. .

  In the first embodiment, the radial tilt coils 43a and 43b are arranged so that the radial tilt magnet 46 is sandwiched in the focus direction. In the second embodiment, the radial tilt coil 302 is sandwiched in the tracking direction. 301a and 301b are arranged. Even in such a configuration, the lens holder, that is, the objective lens, can be tilted in the radial tilt direction with respect to the yoke base, and with a simple configuration, the tilt generated by the warp or surface deflection of the optical disk can be accurately performed. Can be corrected.

1 is a block diagram showing a configuration example of an optical disc apparatus according to the present invention. The top view which looked at the objective lens actuator from the optical disk side. AA sectional drawing in FIG. BB sectional drawing in FIG. The figure which illustrated the positional relationship of a radial tilt magnet and a radial tilt coil including the polarity of a magnet. The top view which looked at the objective-lens actuator concerning 2nd Embodiment from the optical disk side. CC sectional drawing in FIG. The top view which looked at the conventional objective lens actuator from the optical disk side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Objective lens actuator 11 Objective lens 30 Fixed part 33 Lens holder 34 Movable part 35 Yoke base 36 Gel holder 37 Fixed end circuit board 38a, 38b Suspension wire 39a, 39b Suspension wire 40 Radial tilt axis 41a, 41b Tracking coil 42 Focus coil 43a, 43b Radial tilt coil 44 Tracking magnet 45 Focusing magnet 46 Radial tilt magnet 47 Shaft 50 Optical pickup 60 Triaxial control unit 70 Reproduction processing unit 80 Recording processing unit 100 Optical disc device 200 Optical disc

Claims (6)

In an objective lens actuator capable of translational drive in the tracking direction, translational drive in the focus direction, and rotational drive around the radial tilt axis,
An objective lens that focuses the laser beam on the information recording surface of the optical disc;
It has an objective lens at the end, a focus coil that translates the objective lens in the focus direction at the center, and a pair of tracking coils that translate the objective lens in the tracking direction on the side surface of the focus coil A lens holder;
A radial tilt magnet disposed in a cylindrical shape around a radial tilt axis of the lens holder at an end of the lens holder opposite to the objective lens;
A tracking magnet disposed at a position facing the tracking coil;
A focus magnet disposed at a position facing the focus coil;
A fixed portion to which the tracking magnet and the focus magnet are fixed;
A pair of radial tilt coils fixed to the fixing portion and arranged to sandwich the radial tilt magnet therebetween to rotate the lens holder around a radial tilt axis;
An objective lens actuator comprising: a suspension wire having one end fixed to the fixing portion, the other end fixed to the lens holder, and holding the lens holder in a hollow state.   2. The objective lens actuator according to claim 1, wherein the pair of radial tilt coils are arranged with the radial tilt magnet interposed therebetween in a focus direction.   The objective lens actuator according to claim 1, wherein the pair of radial tilt coils are arranged with the radial tilt magnet sandwiched in a tracking direction. An optical pickup comprising an objective lens actuator;
A drive controller for controlling the drive of the objective lens actuator;
A reproduction processing unit for reproducing the signal output from the optical pickup;
A recording processing unit that modulates recording data and outputs the modulated data to the optical pickup as a laser control signal;
The objective lens actuator is
An objective lens actuator capable of translational drive in the tracking direction, translational drive in the focus direction, and rotational drive about the radial tilt axis,
An objective lens that focuses the laser beam on the information recording surface of the optical disc;
It has an objective lens at the end, a focus coil that translates the objective lens in the focus direction at the center, and a pair of tracking coils that translate the objective lens in the tracking direction on the side surface of the focus coil A lens holder;
A radial tilt magnet disposed in a cylindrical shape around a radial tilt axis of the lens holder at an end opposite to the objective lens of the lens holder;
A tracking magnet disposed at a position facing the tracking coil;
A focus magnet disposed at a position facing the focus coil;
A fixed portion to which the tracking magnet and the focus magnet are fixed;
A pair of radial tilt coils fixed to the fixing portion and arranged to sandwich the radial tilt magnet therebetween to rotate the lens holder around a radial tilt axis;
An optical disc apparatus comprising: a suspension wire having one end fixed to the fixing portion, the other end fixed to the lens holder, and holding the lens holder in a hollow state.   5. The optical disc apparatus according to claim 4, wherein the pair of radial tilt coils are arranged with the radial tilt magnet sandwiched in the focus direction.   5. The optical disc apparatus according to claim 4, wherein the pair of radial tilt coils are disposed with the radial tilt magnet interposed therebetween in the tracking direction.

Images