JP2007193856A - Optical information processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove aberrations by using an aberration correction component and reduce the thickness of the whole device. <P>SOLUTION: This optical information processing device has a deflector to deflect the laser beam emitted by a light source toward the optical disk, an imaging means to image the deflected laser beam on the optical disk, an aberration correcting means to correct the aberrations occurring in the light path, between the light source and the disk, maintained optically in a constant positional relationship relative to the imaging means in a predetermined direction. The aberration correcting means is positioned in the light path between the light source and the deflector. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical information processing apparatus that performs information recording processing and reproduction processing on an optical disc, and in particular, deflecting means that deflects laser light emitted from a light source toward the optical disc, and the deflected laser light on the optical disc. An image forming means for forming an image, and an aberration correcting means for correcting an aberration of the laser beam generated in the optical path from the light source to the optical disc, and the laser beam is formed so as to form an image at a predetermined position on the optical disc. The present invention relates to an optical information processing apparatus that moves image means to perform information recording processing and reproduction processing on the optical disc.

  In recent years, optical discs with high recording density such as BD (Blu-Ray Disc) and HD DVD (High Definition DVD) have been standardized, and these are processed ("processing" here includes reproduction, recording, etc.). Such an optical information processing apparatus is widely known. Such an optical information processing apparatus is equipped with a high NA objective lens. A short wavelength light beam is also used. In this way, by using a high NA objective lens and a short wavelength light beam, the optical information processing apparatus forms a very small beam spot on the optical disk, and processes the high-density information on the optical disk. Can do.

  However, when the NA of the objective lens is designed to be high or a light beam with a short wavelength is used, the influence of aberration (for example, spherical aberration) on the beam spot becomes large. That is, the aberration generated by a slight error can greatly affect the formation of a good beam spot. As a result, an error is likely to occur in processing of the optical disk by the optical information processing apparatus.

  The error on the apparatus side can be removed in advance by adjustment work at the time of shipment. Examples of such errors include manufacturing errors of objective lenses. Such an error can be removed, for example, by performing axial alignment or tilt adjustment of the objective lens.

  On the other hand, errors on the optical disk side cannot be removed by adjustment work on the apparatus side. For this reason, an aberration is generated due to the above error depending on the optical disc, and the beam spot is deteriorated. As a result, the processing on the optical disc may not be performed well. Examples of errors on the optical disk side include individual differences of optical disks, recording layer thickness errors, and unevenness.

  In order to solve such a problem, for example, an optical information processing apparatus in which a liquid crystal element for aberration correction is mounted is disclosed in Patent Document 1 below. In the optical information processing apparatus described in Patent Document 1 below, by applying different voltages to the electrodes of the liquid crystal element to adjust the alignment state of the liquid crystal molecules, the phase of the light beam passing through the liquid crystal element is shifted. Aberration correction is realized. Since the error of the optical disk is detected when the optical disk is set, and the phase shift amount is determined according to the detection result, the error on the optical disk side is satisfactorily removed.

Here, as described in Patent Document 1 below, the positional relationship between the objective lens and the liquid crystal element is required to be constant in order to satisfactorily correct the aberration by the liquid crystal element. Therefore, in the following Patent Document 1, the liquid crystal element is fixed to the objective lens and configured as one unit. In this configuration, since the liquid crystal element and the objective lens move together, the mutual positional relationship is always kept constant. Thereby, good aberration correction is realized.
JP 2002-56565 A

  A very thin ODD (Optical Disk Drive) called “slim size” or “ultra slim” is generally mounted on a thin terminal such as a notebook PC. However, in the optical information processing apparatus described in Patent Document 1, the thickness of the entire apparatus increases due to the addition of the liquid crystal element. For this reason, in the optical information processing apparatus described in Patent Document 1, it has been difficult to realize the thin size.

  Therefore, in view of the above circumstances, an object of the present invention is to provide an optical information processing apparatus that can satisfactorily remove aberration by an aberration correction element and suppress the thickness of the entire apparatus.

  An optical information processing apparatus according to an aspect of the present invention that solves the above-described problems is an apparatus that performs information recording processing or reproduction processing on an optical disc. This optical information processing apparatus includes an optical unit composed of a deflection unit that deflects laser light emitted from a light source toward the optical disc, an imaging unit that forms an image of the deflected laser beam on the optical disc, and an imaging unit. Aberration correction means for correcting the aberration of laser light generated in the optical path from the light source to the optical disk, in which the relative positional relationship is kept constant in a predetermined direction, and the aberration correction means is a light source and deflection means. It is characterized by being arranged in the optical path between the two.

  According to the optical information processing apparatus, the image forming means and the aberration correcting means are arranged with the deflecting means sandwiched in the optical path of the laser light. For this reason, the image forming means and the aberration correcting means are not arranged side by side in the thickness direction of the apparatus. Therefore, according to the optical information processing apparatus, it is possible to satisfactorily remove the aberration by the aberration correction element and to suppress the thickness of the entire apparatus.

  In the optical information processing apparatus, for example, the optical relative positional relationship between the imaging unit and the first moving unit that moves the imaging unit so that the laser beam is imaged at a predetermined position on the optical disk is constant. There may be further provided a second moving means for moving the aberration correcting means so as to be held by the lens.

  According to the optical information processing apparatus, the aberration correction unit is configured to be independently movable with respect to the imaging unit. That is, since the image forming unit and the aberration correcting unit move in a separated configuration, the image forming unit is reduced in weight and the followability is improved. In other words, the response speed of the imaging means is improved and the imaging means can move precisely and at high speed.

  According to the optical information processing apparatus, the first moving means can move the imaging means in the radial direction of the optical disc.

  Further, according to the optical information processing apparatus, the second moving unit can move the aberration correcting unit in a direction orthogonal to the surface of the optical disc. According to another aspect, the second moving means can move the aberration correcting means in the radial direction of the optical disc.

  An optical information processing apparatus according to another aspect of the present invention that solves the above-described problems includes a deflecting unit that deflects laser light emitted from a light source toward an optical disc, and forms an image of the deflected laser light on the optical disc. And an aberration correction unit that corrects the aberration of the laser beam generated in the optical path from the light source to the optical disc, and forms an image so that the laser beam is imaged at a predetermined position on the optical disc. It is an apparatus that moves the means to perform information recording processing or reproducing processing on the optical disc. In this optical information processing apparatus, the optical relative positional relationship between the moving means for moving the aberration correcting means independently of the imaging means and the aberration correcting means and the imaging means is constant with respect to a predetermined direction. And a movement control means for controlling the movement means to be held. The aberration correction means is disposed in the optical path between the light source and the deflection means.

  According to the optical information processing apparatus, the image forming means and the aberration correcting means are arranged with the deflecting means sandwiched in the optical path of the laser light. For this reason, the image forming means and the aberration correcting means are not arranged side by side in the thickness direction of the apparatus. Therefore, according to the optical information processing apparatus, it is possible to satisfactorily remove the aberration by the aberration correction element and to suppress the thickness of the entire apparatus. Further, the aberration correction means is configured to be able to move independently of the imaging means. That is, since the image forming unit and the aberration correcting unit move in a separated configuration, the image forming unit is reduced in weight and the followability is improved. In other words, the response speed of the imaging means is improved and the imaging means can move precisely and at high speed.

  The optical information processing apparatus may further include, for example, position information detection means for detecting position information of the imaging means. In this case, the movement control means can control the movement means based on the detected position information.

  Further, according to the optical information processing apparatus, the moving means can move the aberration correcting means in a direction orthogonal to the surface of the optical disc.

  According to the optical information processing apparatus of the present invention, the image forming means and the aberration correcting means are arranged with the deflection means sandwiched in the optical path of the laser light. For this reason, the image forming means and the aberration correcting means are not arranged side by side in the thickness direction of the apparatus. Therefore, according to the optical information processing apparatus, it is possible to satisfactorily remove the aberration by the aberration correction element and to suppress the thickness of the entire apparatus.

  The configuration and operation of the optical information processing apparatus according to the embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing a configuration of an optical information processing apparatus 100 according to a first embodiment of the present invention. The optical information processing apparatus 100 includes a housing 1. The housing 1 is formed with a slot 1a. Further, a tray (not shown) is provided so as to be able to be stored / discharged with respect to the housing 1 through the slot 1a. Note that FIG. 1 shows a state in which the optical disk 200 placed on the tray is stored in the housing 1. In the stored state, the optical disc 200 is set on the spindle motor 70. The optical disk 200 is rotated about a rotation shaft 70a by a spindle motor 70. The optical disc 200 is an optical disc having a high recording density, such as a BD or HD DVD.

  The optical information processing apparatus 100 includes a fixed unit 10 and a movable unit 30. FIG. 2 shows configurations of the fixed unit 10 and the movable unit 30. These units are held in the housing 1.

  The fixed unit 10 includes a laser diode 11, a collimator lens 12, a first anamorphic prism 13, a half mirror 13a, a second anamorphic prism 14, a mirror 15, a right-angle prism 16, a hologram element 17, a condensing lens 18, and a composite sensor 19. And a laser power monitor sensor 20.

  The laser diode 11 emits divergent laser light having an elliptical cross section. This divergent laser light has a short wavelength (for example, near 400 nm). The divergent laser light emitted from the laser diode 11 enters the collimator lens 12. The collimator lens 12 converts the divergent laser light emitted from the laser diode 11 into a parallel light beam. The parallel light beam converted into the parallel light beam enters the first anamorphic prism 13.

  The first anamorphic prism 13 and the second anamorphic prism 14 shape the parallel light beam from the collimator lens 12 into a parallel light beam having a substantially circular cross-sectional shape. Next, the parallel light flux whose cross-sectional shape is shaped into a substantially circular shape enters the mirror 15. Further, a part of the parallel light beam incident on the first anamorphic prism 13 is bent 90 degrees by the half mirror 13 a and is incident on the laser power monitor sensor 20.

  The laser power monitor sensor 20 outputs a signal corresponding to the intensity of received light to a laser power control circuit (not shown). The laser power control circuit performs feedback control based on the level of the received signal to stabilize the output of the laser diode 11.

  On the other hand, the mirror 15 bends the parallel light beam emitted from the second anamorphic prism 14 by 90 degrees. The bent laser light is emitted from the fixed unit 10 and enters the movable unit 30.

  The movable unit 30 includes a carriage 31. The carriage 31 is slid in the radial direction of the optical disc 200 (that is, the tracking direction and the arrow T direction shown in each figure) by guide shafts 33R and 33L each end of which is fixed at a predetermined position of the housing 1. Supported as possible. Further, driving means for moving the movable unit 30 in the tracking direction is installed so as to sandwich the carriage 31. Specifically, a yoke 34R fixed at a predetermined position of the casing 1 on the guide shaft 33R side, a coil 35R through which the yoke 34R is inserted, a yoke 34L fixed at a predetermined position of the casing 1 on the guide shaft 33L side, and A coil 35L through which the yoke 34L is inserted is installed. When a current flows through the coils 35R and 35L fixed to the carriage 31 by a drive control circuit (not shown), thrust is generated by electromagnetic action, thereby moving the carriage 31 in the tracking direction.

  Further, the carriage 31 has an opening 31 a in a wall portion facing the fixed unit 10. The laser beam emitted from the fixed unit 10 enters the carriage 31 through the opening 31a.

  FIG. 3 shows a perspective view of the movable unit 30 with a part of the carriage 31 cut out. FIG. 4 shows a cross-sectional view of the movable unit 30. In FIG. 3, for convenience of explanation, the carriage 31 is divided into two parts in the vertical direction.

  In the carriage 31, an aberration correction unit 40, a quarter-wave plate 42, a rising mirror 32, and an objective lens unit 50 are installed. The aberration correction unit 40, the quarter wavelength plate 42, and the rising mirror 32 are arranged in a direction parallel to the surface of the optical disc 200. Further, the raising mirror 32 and the objective lens unit 50 are arranged in a direction perpendicular to the surface of the optical disc 200. Laser light that has entered the carriage 31 through the opening 31 a enters the aberration correction unit 40.

  The aberration correction unit 40 includes a liquid crystal aberration correction element 41. The liquid crystal aberration correction element 41 is attached to the frame 40a.

  The liquid crystal aberration correction element 41 is a plate-like element that has a known configuration and is arranged on a plane parallel to the arrow F and orthogonal to the arrow T. The liquid crystal aberration correction element 41 includes a liquid crystal that changes birefringence with respect to incident laser light by an electric field generated according to the amount of applied voltage. That is, the alignment state of each of a plurality of liquid crystal molecules constituting the liquid crystal is changed by an electric field generated according to the amount of applied voltage in the liquid crystal aberration correction element 41. By changing the alignment state of each liquid crystal molecule, light passing through the liquid crystal molecules undergoes a birefringence change. As a result, the phase of the light changes. Here, a change in the phase of the incident laser light also means a change in the aberration of the light. Therefore, the aberration (mainly spherical aberration) can be corrected by changing the phase by an appropriate amount by the liquid crystal aberration correction element 41.

  The liquid crystal aberration correcting element 41 has a plurality of electrodes for generating an electric field. These electrodes are arranged so as to be distributed on the liquid crystal aberration correction element 41. Therefore, when a voltage is applied to each electrode, the alignment state of the liquid crystal molecules is distributed on the liquid crystal aberration correction element 41 according to the amount of voltage applied to each electrode. By controlling the voltage so that the orientation state is distributed on the liquid crystal aberration correction element 41 in accordance with the aberration distribution of the laser light, the aberration of the laser light generated in the optical path is favorably corrected.

  The movable unit 30 has a flexible substrate 36 connected to the drive control circuit. Each component of the movable unit 30 is operated by a signal input via the flexible substrate 36.

  The laser light that has passed through the liquid crystal aberration correction element 41 is in a linearly polarized state. The laser beam in such a polarization state is converted into circularly polarized light by the quarter wavelength plate 42 held by the carriage 31 and enters the rising mirror 32. Next, it is raised in the vertical direction (direction perpendicular to the surface of the optical disc 200) by the raising mirror 32 and enters the objective lens unit 50.

  The objective lens unit 50 includes an objective lens holder 51. The objective lens holder 51 holds the objective lens 52. The objective lens 52 is designed to have a high NA (for example, NA = 0.85). Note that the positions of the objective lens 52 and the liquid crystal aberration correction element 41 shown in FIG. 4 are the respective reference positions. The reference position of the objective lens 52 is a position when the optical axis of the objective lens 52 coincides with the optical axis of the entire optical information processing apparatus 100 (the axis indicated by the alternate long and short dash line in each drawing). The reference position of the liquid crystal aberration correction element 41 is a position when the center 41 c of the liquid crystal aberration correction element 41 is on the optical axis of the entire optical information processing apparatus 100.

  The laser beam raised by the raising mirror 32 enters the objective lens 52 and is focused on the optical disc 200 as a minute beam spot. The optical disc 200 has a thin recording layer 200a and a disc substrate 200b on which information is recorded. More precisely, the beam spot is formed on the recording layer 200a.

  That is, the laser beam emitted from the objective lens 52 forms an image on the optical disc 200 with the aberrations corrected by the action of each optical system and the liquid crystal aberration correction element 41. Next, the light is reflected by the optical disc 200. The laser light reflected by the optical disc 200 enters the fixed unit 10 as return light via the movable unit 30. Next, the return light is bent 90 degrees by the mirror 15 and guided to the second anamorphic prism 14. The return light transmitted through the second anamorphic prism 14 is bent 90 degrees by the half mirror 13 a and is incident on the right-angle prism 16 and the hologram element 17.

  The hologram element 17 is a light beam separation element. In the first embodiment, the hologram element 17 separates the return light incident through the right-angle prism 16 into three light beams that are directed in different directions. The three separated light beams enter the composite sensor 19 via the condenser lens 18.

  The composite sensor 19 includes a servo light receiving element and a data light receiving element (not shown). These light receiving elements are arranged along the three light beams separated by the hologram element 17. One of the three light beams is received by the light receiving element for data and is processed as an information signal of the optical disc 200.

  The remaining two of the light beams separated by the hologram element 17 are received by the servo light receiving element. The output of the light receiving element for servo is subjected to arithmetic processing by an arithmetic unit (not shown) and detected as a focus error signal and a tracking error signal. Based on each error signal, the biaxial actuator of the objective lens unit 50 is driven, and minute adjustments regarding the position of the objective lens 52 such as tracking are performed.

  Here, the biaxial actuator of the objective lens unit 50 will be described. 5 and 6 are exploded perspective views of the components inside the carriage 31. FIG. As the biaxial actuator of the objective lens unit 50, a so-called moving coil type in which the coil itself moves is employed.

  The objective lens unit 50 includes an actuator base 53, a wire 54, a wire fixing block 55, a focus coil 56, a focus magnet 57, a tracking coil 58, and a tracking magnet 59 in addition to the objective lens holder 51 and the objective lens 52. Yes.

  The actuator base 53 is held by the carriage 31. The objective lens holder 51 is movably mounted on the actuator base 53. A pair of focus coils 56 are wound around the objective lens holder 51 so as to sandwich the objective lens 52 in a direction orthogonal to the arrow T. A pair of tracking coils 58 is wound around the objective lens 52 in the arrow T direction.

  Two wires 54 are attached to both sides of the objective lens holder 51. Each of the wires 54 has one end attached to the objective lens holder 51 and the other end attached to a wire fixing block 55 held by the carriage 31. These wires 54 are made of, for example, a conductive member. A current is supplied to each of the focus coil 56 and the tracking coil 58 via the wire 54 by the drive control circuit.

  Four focus magnets 57 are fixed to the actuator base 53. Two focus magnets 57 are arranged on both sides of the objective lens holder 51 in a direction orthogonal to the arrow T. At each fixed location, the focus magnets 57 are arranged in the direction of arrow F (that is, the focus direction, the direction perpendicular to the surface of the optical disc 200). A focus coil 56 is positioned close to each focus magnet 57.

  When an electric current is supplied to the focus coil 56, the objective lens holder 51 is moved by the thrust (repulsive force, attractive force) generated between the magnetic force generated thereby and the magnetic force of the focus magnet 57 close to the focus coil 56. Moving. At this time, the objective lens holder 51 translates only in the focus direction (that is, the direction of arrow F) while bending the wire 54 due to the positional relationship between the focus coil 56 and the focus magnet 57. The moving range is from a position where the objective lens holder 51 is placed on the actuator base 53 to a position where the thrust balances with the restoring force of the wire 54. The amount of movement of the objective lens holder 51 in the focus direction is determined based on the focus error signal. The objective lens 52 can form a suitable beam spot on the optical disc 200 by such a focusing operation.

  Four tracking magnets 59 are fixed to the actuator base 53. Two of these tracking magnets 59 are arranged on both sides of the objective lens holder 51 in the direction of arrow T. Further, the tracking magnets 59 are arranged in the direction of the arrow T across the focus magnet 57 at each fixed location. A tracking coil 58 is located close to each tracking magnet 59.

  When a current is supplied to the tracking coil 58, the objective lens holder 51 is moved by a thrust generated between the magnetic force generated thereby and the magnetic force of the tracking magnet 59 adjacent to the tracking coil 58. At this time, the objective lens holder 51 translates only in the tracking direction (that is, the arrow T direction) while bending the wire 54 due to the positional relationship between the tracking coil 58 and the tracking magnet 59. The moving range is determined by a balance position between the thrust and the restoring force of the wire 54. The amount of movement of the objective lens holder 51 in the tracking direction is determined based on the tracking error signal. The objective lens 52 can form a beam spot at an appropriate position on the optical disc 200 by such a tracking operation.

  In a state where no current is supplied to each focus coil 56 and tracking coil 58 (that is, when the actuator is not driven), the objective lens unit 50 is located at the reference position (that is, the position shown in FIG. 4).

  In the first embodiment, from the viewpoint of reducing the weight of the objective lens holder 51, the objective lens holder 51 is a resin molded product made of a so-called engineering plastic or the like. Therefore, each of the focus coil 56 and the tracking coil 58 functions as a hollow coil.

  The objective lens unit 50 further includes a pair of well-known reflection type photo interrupters 60. The reflection type photo interrupter 60 includes a light projecting unit 60a that projects projection light and a light receiving unit 60b that receives the projection light. Each of these reflection type photo interrupters 60 is installed to face each wall 51 a of the objective lens holder 51.

  The wall part 51a of the objective lens holder 51 has a plane reflection surface, and can reflect the projection light projected from the light projecting part 60a. When the reflected light is received by the light receiving unit 60b, a signal corresponding to an intensity change proportional to the distance to the reflecting surface is generated and output to the drive control circuit. The drive control circuit detects a displacement in the tracking direction of the objective lens unit 50 with respect to the reference position based on a signal from each reflection type photo interrupter 60. The control of displacement detection and the like is disclosed in Japanese Utility Model Laid-Open No. 5-21331 by the present applicant.

  Next, the aberration correction unit 40 will be described in detail. In the first embodiment, in order to reduce the thickness of the optical information processing apparatus 100 and further reduce the weight of the objective lens unit 50, the objective lens unit 50 and the aberration correction unit 40 are configured as independent units.

  First, the configuration of the aberration correction unit 40 will be described.

  In the direction orthogonal to the arrows T and F, two liquid crystal driving magnets 43 are attached to both side surfaces of the frame 40a. Further, the liquid crystal driving magnets 43 are arranged in the direction of the arrow F at each fixed portion.

  In the vicinity of each liquid crystal drive magnet 43, a pair of liquid crystal drive coils 44 is installed with the liquid crystal aberration correction element 41 interposed therebetween. These liquid crystal driving coils 44 are held by the carriage 31. These liquid crystal drive coils 44 are hollow coils and are connected to the drive control circuit.

  The liquid crystal aberration correction element 41 is held between a pair of leaf springs 45 extending in a direction orthogonal to the arrows T and F. One end of these leaf springs 45 is held by the carriage 31. The power supply to the liquid crystal aberration correction element 41 is performed using, for example, an electrode pattern formed on the leaf spring 45.

  Next, the operation of the aberration correction unit 40 will be described. The aberration correction unit 40 employs a so-called moving magnet type actuator in which the magnet itself moves.

  When a current is supplied to the liquid crystal driving coil 44, a liquid crystal driving magnet 43 () is generated by a thrust generated between the magnetic force generated thereby and the magnetic force of the liquid crystal driving magnet 43 adjacent to the liquid crystal driving coil 44. Then, the frame 40a and the liquid crystal aberration correction element 41) move. At this time, these members move in parallel only in the direction of the arrow T ′ while bending the leaf spring 45 according to the positional relationship between the liquid crystal driving magnet 43 and the liquid crystal driving coil 44. The moving range is determined by a balance position between the thrust and the restoring force of the leaf spring 45. For convenience of explanation, members that move by thrust, that is, the frame 40a, the liquid crystal aberration correction element 41, and the liquid crystal drive magnet 43 are referred to as “liquid crystal movable portion 40M”.

  In a state where no current is supplied to each liquid crystal driving coil 44 (that is, when the actuator is not driven), the liquid crystal movable portion 40M is located at the reference position.

Here, the amount of movement of the liquid crystal movable part 40M in the direction of the arrow T ′ is determined based on the displacement of the objective lens unit 50 detected using the reflective photointerrupter 60. 7A to 7C are diagrams for explaining the position tracking of the liquid crystal movable unit 40M with respect to the objective lens unit 50. FIG. In FIGS. 7A to 7C, for the sake of simplification of the drawing, the illustration of the configuration that is unnecessary for the description of the position tracking is omitted. For convenience of explanation, “O ₁ ” is attached to the optical axis of the objective lens 52, and “O ₂ ” is attached to an axis that passes through the center 41 c of the liquid crystal aberration correction element 41 and is parallel to the optical axis O ₁ . In a state where the optical axis O ₁ and the axis O ₂ coincide with each other (for example, the state of FIG. 7A), the liquid crystal aberration correction element 41 can satisfactorily correct the aberration.

  The drive control circuit first calculates a displacement in the tracking direction of the objective lens unit 50 with respect to the reference position, that is, position information of the objective lens unit 50 based on the output of the reflective photointerrupter 60. Next, a current value to be supplied to the liquid crystal driving coil 44 is set based on the calculated position information. When the current thus set is supplied to the liquid crystal driving coil 44, the leaf spring 45 is bent by the generated thrust. Accordingly, the liquid crystal movable unit 40M moves so that the optical axis of the objective lens unit 50 and the center 41c of the liquid crystal aberration correction element 41 coincide with each other in the tracking direction. That is, the position tracking of the liquid crystal movable part 40M with respect to the objective lens unit 50 is executed.

  For example, as shown in FIG. 7B, when the objective lens unit 50 moves a distance d from the position of FIG. 7A toward the inner peripheral side of the optical disc 200 along the tracking direction T, the drive control circuit Based on the output of each reflective photointerrupter 60, the liquid crystal movable part 40M is operated to follow.

That is, the drive control circuit obtains the output intensity of each reflective photointerrupter 60 and calculates the position information of the objective lens unit 50. Next, in order to keep the optical relative positional relationship between the objective lens unit 50 and the liquid crystal aberration correction element 41 constant with respect to the tracking direction of the optical disc 200, a predetermined level of current is supplied to the liquid crystal driving coil 44 based on the calculated position information. Supply. Thereby, the liquid crystal movable part 40M moves the distance d from the position of FIG. 7A in the direction of the arrow T ₁ ′ (direction orthogonal to the optical disk 200 and approaching the optical disk 200). That is, the drive control circuit moves the liquid moving part 40M so as to match the optical axis O ₁ and the shaft O _2. Thus, the position tracking of the liquid crystal movable part 40M with respect to the objective lens unit 50 is achieved.

  For example, as shown in FIG. 7C, when the objective lens unit 50 moves a distance d from the position of FIG. 7A toward the outer periphery of the optical disc 200 along the tracking direction T, the drive control circuit Based on the output of each reflective photointerrupter 60, the liquid crystal movable part 40M is operated to follow.

Also in this case, the drive control circuit calculates the position information of the objective lens unit 50 by acquiring the output intensity of each reflection type photo interrupter 60. Next, in order to keep the optical relative positional relationship between the objective lens unit 50 and the liquid crystal aberration correction element 41 constant with respect to the tracking direction of the optical disc 200, a predetermined level of current is supplied to the liquid crystal driving coil 44 based on the calculated position information. Supply. As a result, the liquid crystal movable part 40M moves a distance d from the position of FIG. 7A in the direction of the arrow T ₂ ′ (the direction orthogonal to the optical disk 200 and away from the optical disk 200). That is, the drive control circuit Again moves the liquid moving part 40M so as to match the optical axis O ₁ and the shaft O _2. Thus, the position tracking of the liquid crystal movable part 40M with respect to the objective lens unit 50 is achieved.

  The position tracking of the liquid crystal movable part 40M with respect to the objective lens unit 50 is always performed. Therefore, the optical axis of the objective lens unit 50 and the center 41c of the liquid crystal aberration correction element 41 always coincide with each other in the tracking direction. Since the optical relative positional relationship between the objective lens unit 50 and the liquid crystal aberration correction element 41 is always constant, the aberration correction by the liquid crystal aberration correction element 41 is always performed satisfactorily.

  Further, the optical information processing apparatus 100 can be thinned by configuring the objective lens unit 50 and the aberration correction unit 40 as independent units. That is, in the first embodiment, since the objective lens unit 50 and the aberration correction unit 40 are separated, the objective lens unit 50 and the aberration correction unit 40 are arranged in different directions without being arranged along the same direction. It is realized to arrange in In the first embodiment, the aberration correction unit 40 is arranged along with the other components in a direction parallel to the surface of the optical disc 200. On the other hand, the objective lens unit 50 is arranged along with other components in a direction orthogonal to the surface of the optical disc 200. That is, in the first embodiment, the aberration correction unit 40 is not arranged in line with the objective lens unit 50 in the direction orthogonal to the surface of the optical disc 200 (that is, the thickness direction of the optical information processing apparatus 100). As a result, the movable unit 30 is reduced in thickness, and as a result, the entire optical information processing apparatus 100 is also reduced in thickness.

  Further, by configuring the objective lens unit 50 and the aberration correction unit 40 as independent units, the weight of the objective lens unit 50 is realized. Therefore, the followability of the objective lens unit 50 with respect to the tracking direction of the optical disc 200 is improved. That is, the response speed of the objective lens unit 50 is improved and the objective lens unit 50 can be moved accurately and at high speed. As a result, it is possible to provide an optical information processing apparatus that can sufficiently cope with an increase in the density and rotation speed of an optical disc.

  Next, the configuration and operation of the optical information processing apparatus according to the second embodiment of the present invention will be described.

  FIG. 8 shows the configuration of the optical information processing apparatus 100z of the second embodiment. The optical information processing apparatus 100z is a type in which laser light is incident on an objective lens from a light source in a tangential direction (tangential direction) of an optical disc. This type has an advantage in thinning. In the optical information processing apparatus 100z shown in the following drawings (FIGS. 8 to 10), the same or similar components as those in the optical information processing apparatus 100 of the first embodiment are denoted by the same or similar reference numerals. The description in is omitted. Also, in FIGS. 8 to 10, for simplification of the drawings, a part of the configuration overlapping with the description of the first embodiment is omitted.

  FIG. 8A shows a perspective view of the optical information processing apparatus 100z of the second embodiment. The optical information processing apparatus 100z includes a movable unit 130. The movable unit 130 has a carriage 131. The carriage 131 is slid in the radial direction of the optical disc 200 (that is, the tracking direction and the arrow TT direction shown in each figure) by guide shafts 133R and 133L each end of which is fixed at a predetermined position of the housing 1. Supported as possible. The carriage 131 holds each component of the movable unit 130 and can be slid in the direction of the arrow TT by driving means (not shown).

  FIG. 8B shows a cross section of the movable unit 130 and its peripheral structure. 9 shows a top view of the optical information processing apparatus 100z further simplified with respect to FIG. As shown in these drawings, the carriage 131 holds a laser diode 111, an anamorphic prism 112, a collimator lens 113, an error detection lens 114, a photo sensor 115, a rising mirror 132, and a quarter wavelength plate 142. is doing. The carriage 131 holds the liquid crystal aberration correction element 141 and the objective lens unit 150 movably. The liquid crystal aberration correction element 141 and the objective lens unit 150 can be moved in a predetermined direction by the moving magnet type or moving coil type actuator (not shown) as described above. The objective lens unit 150 includes an objective lens holder 151 and an objective lens 152.

  Laser light emitted from the laser diode 111 enters the liquid crystal aberration correction element 141 through the anamorphic prism 112 and the collimator lens 113. The phase of the laser light is changed by the liquid crystal aberration correction element 141 and enters the rising mirror 132 via the quarter-wave plate 142. Then, it is deflected by the reflecting surface 132 a of the rising mirror 132 and enters the objective lens 152, and the focal point is formed on the optical disc 200 by the action of the objective lens 152. Next, the return light is reflected by the half mirror 112 a of the anamorphic prism 112 and received by the photo sensor 115 via the error detection lens 114. The laser beam received by the photosensor 115 is used as an information signal, a focus error signal, and a tracking error signal of the optical disc 200 as described above.

  The drive control circuit finely adjusts the objective lens unit 150 in the arrow TT direction by an actuator (not shown) based on the tracking error signal. Also in the second embodiment, in order to keep the optical relative positional relationship between the objective lens unit 150 and the liquid crystal aberration correction element 141 constant with respect to the tracking direction of the optical disc 200, the drive control circuit includes the liquid crystal aberration correction element 141. Perform movement control.

  FIGS. 10A and 10B are diagrams for explaining the position tracking of the liquid crystal aberration correction element 141 with respect to the objective lens unit 150. FIG.

  The drive control circuit first calculates the displacement (position information) of the objective lens unit 150 based on the output of a detection means (not shown) such as a reflective photointerrupter. Next, a current value to be supplied to an actuator (not shown) is set based on the calculated position information. When the current set in this way is supplied to the actuator, the liquid crystal aberration correcting element 141 moves in the direction of the same arrow TT as the objective lens unit 150. For example, as shown in FIG. 10A, when the objective lens unit 150 moves away from the center of the optical disc 200 along the direction of the arrow TT, the liquid crystal aberration correction element 141 is also controlled by the drive control circuit. Move the same distance away from the center along the direction of arrow TT. For example, as shown in FIG. 10B, when the objective lens unit 150 moves along the direction of the arrow TT toward the center of the optical disc 200, the liquid crystal aberration correction element 141 is also controlled by the drive control circuit. Moves the same distance along the direction of arrow TT toward the center. In this way, the position tracking of the liquid crystal aberration correction element 141 with respect to the objective lens unit 150 is realized.

  The above is the embodiment of the present invention. The present invention is not limited to these embodiments and can be modified in various ranges. For example, in the embodiment of the present invention, a moving coil type or moving magnet type actuator is employed, but in other embodiments, other various actuators that can be assumed may be employed.

  In the first embodiment, the aberration correction unit 40 is disposed inside the movable unit 30. However, in another embodiment, the aberration correction unit 40 may be disposed inside the fixed unit 10. In this case, weight reduction of the movable unit 30 is implement | achieved.

  In the first embodiment, the objective lens unit 50 and the aberration correction unit 40 are held by separate housings. However, in another embodiment, the objective lens unit 50 and the aberration correction are performed as in the second embodiment. The unit 40 may be configured to be held by a single housing. In this case, the objective lens unit 50 and the aberration correction unit 40 can be moved by a single actuator while keeping the relative positional relationship constant. Since the number of actuators can be reduced, manufacturing costs can be reduced.

It is the perspective view which showed the structure of the optical information processing apparatus of the 1st Example of this invention. The structure of the fixed unit and the movable unit with which the optical information processing apparatus of the 1st Example of this invention was equipped is shown. The perspective view of the movable unit of the 1st example of the present invention is shown. Sectional drawing of the movable unit with which the optical information processing apparatus of the 1st Example of this invention was equipped is shown. The disassembled perspective view of each component inside the carriage with which the movable unit of the 1st Example of this invention was equipped is shown. The disassembled perspective view of each component inside the carriage with which the movable unit of the 1st Example of this invention was equipped is shown. It is a figure for demonstrating the position tracking of the liquid-crystal movable part with respect to the objective lens unit in the 1st Example of this invention. It is the figure which showed the structure of the optical information processing apparatus of the 2nd Example of this invention. The top view of the optical information processing apparatus of the 2nd Example of this invention is shown. It is a figure for demonstrating the position tracking of the liquid-crystal aberration correction element with respect to the objective lens unit in the 2nd Example of this invention.

Explanation of symbols

30, 130 Movable unit 40 Aberration correction unit 41, 141 Liquid crystal aberration correction element 40M Liquid crystal movable part 50, 150 Objective lens unit 52, 152 Objective lens 60 Reflection type photo interrupter 100, 100z Optical information processing apparatus

Claims (8)

In an optical information processing apparatus for performing information recording processing or reproduction processing on an optical disc,
Deflecting means for deflecting laser light emitted from the light source toward the optical disc;
Imaging means for imaging the deflected laser beam on the optical disc;
An aberration correction unit that corrects an aberration of laser light generated in an optical path from the light source to the optical disc, in which an optical relative positional relationship with the imaging unit is held constant in a predetermined direction, and
An optical information processing apparatus, wherein the aberration correction unit is disposed in an optical path between the light source and the deflection unit. First moving means for moving the imaging means so that a laser beam is imaged at a predetermined position on the optical disc;
The light according to claim 1, further comprising: a second moving unit that moves the aberration correcting unit so that an optical relative positional relationship with the imaging unit is maintained constant. Information processing device.   The optical information processing apparatus according to claim 2, wherein the first moving unit moves the imaging unit in a radial direction of the optical disc.   4. The optical information processing apparatus according to claim 2, wherein the second moving unit moves the aberration correcting unit in a direction orthogonal to the surface of the optical disc.   The optical information processing apparatus according to claim 2, wherein the second moving unit moves the aberration correcting unit in a radial direction of the optical disc. Deflection means for deflecting the laser light emitted from the light source toward the optical disc, imaging means for forming an image of the deflected laser light on the optical disc, and laser light generated in the optical path from the light source to the optical disc. Aberration correction means for correcting aberration, and light for performing information recording processing or reproduction processing on the optical disc by moving the imaging means so that the laser beam is imaged at a predetermined position on the optical disc In an information processing device,
Moving means for independently moving the aberration correction means independently of the imaging means;
Movement control means for controlling the movement means so that the optical relative positional relationship between the aberration correction means and the imaging means is held constant with respect to a predetermined direction,
An optical information processing apparatus, wherein the aberration correction unit is disposed in an optical path between the light source and the deflection unit. Further comprising position information detecting means for detecting position information of the imaging means;
The optical information processing apparatus according to claim 6, wherein the movement control unit controls the movement unit based on the detected position information.   The optical information processing apparatus according to claim 6, wherein the moving unit moves the aberration correcting unit in a direction orthogonal to the surface of the optical disc.

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