JP2008243251A - Optical head and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in an optical head loaded with a plurality of objective lenses in a shared holder, information at the innermost position of an optical disk is difficult to read etc. using an objective lens disposed on the outer periphery side of the disk and that depending on the variance of component precision, the holder or the objective lens can collide with a turntable when the holder moves to the inner periphery side. <P>SOLUTION: An optical disk device comprises the optical head which has the objective lenses for condensing a luminous flux on the optical disk, the holder for holding the objective lenses, and drive means for driving the holder in a tracking direction being generally the radial direction of the optical disk and a focusing direction generally vertical to the face of the optical disk. In the holder, at a position facing the outer periphery end face of the turntable, cushioning means are disposed projecting from the outer periphery end faces of the objective lenses toward the side of the turntable. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that records or reproduces information on an information recording medium such as a DVD recorder or a BD player, and an optical head used in the optical disc apparatus.

  In recent years, various types of optical discs having different recording densities and cover layer thicknesses have been developed as information recording media. For example, CD (Compact Disc) having a used wavelength of around 780 nm, DVD (Digital Versatile Disc) having a used wavelength of around 660 nm, BD (Blu-Ray Disc) and HD-DVD (High Definition) having a used wavelength of around 405 nm. DVD) and the like have been developed. As an optical disk apparatus capable of supporting a plurality of types of optical disks having different use wavelengths as described above, an optical disk apparatus having a plurality of objective lenses for forming a focused spot suitable for each optical disk has been proposed (for example, , See Patent Document 1).

JP2003-281758 (paragraph 0034-0064, FIG. 2-6)

  However, in the conventional optical disc device described in Patent Document 1, since the two objective lenses are mounted on the lens holder so as to be aligned in the radial direction of the optical disc, the objective lens arranged on the inner peripheral side and the optical disc are arranged. It is difficult to ensure a sufficient gap with the turntable to be held. Therefore, in particular, it is difficult to read and write information on the innermost peripheral position of the optical disc using the objective lens arranged on the outer peripheral side of the optical disc among the two objective lenses. Further, depending on variations in component dimensions, when the lens holder moves to the inner circumference side of the optical disc, the turntable may collide with the objective lens or the lens holder, resulting in deterioration or damage of the characteristics of the optical disc apparatus. .

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to deteriorate characteristics by preventing a collision with a peripheral member in an optical head and an optical disk apparatus equipped with a plurality of objective lenses. It is intended to suppress damage and damage, thereby improving reliability and assembly, and facilitating reading of information on the innermost peripheral position of the optical disk.

  An optical disc apparatus according to the present invention includes a plurality of objective lenses that focus a light beam on an optical disc, a holder that holds the objective lens, and a holder that has a tracking direction that is a substantially radial direction of the optical disc, and a surface of the optical disc. The optical head includes a driving unit that drives in a vertical focusing direction, and a turntable that holds and rotates the optical disk. In the holder, a buffering means protruding from the outer peripheral end surface of the objective lens toward the turntable is disposed at a position facing the outer peripheral end surface of the turntable.

  According to the present invention, the shock absorber provided in the holder can prevent the objective lens and the holder from colliding with the turntable, so that the deterioration and damage of the characteristics of the optical head and the optical disk apparatus can be suppressed, and the reliability is improved. To do. In addition, since the collision between the objective lens and the holder during the assembling work and the turntable can be prevented, the assembling property is also improved. Furthermore, it is possible to easily read and write information on the innermost peripheral position of the optical disk by bringing the holder closer to the turntable.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing the main part of the optical disc apparatus according to Embodiment 1 of the present invention. 2 and 3 are a perspective view and an exploded perspective view showing an objective lens actuator of the optical head in the optical disc apparatus according to Embodiment 1. FIG.

  As shown in FIG. 1, the optical disc apparatus includes a turntable 102 on which an optical disc 101 is placed, a spindle motor 103 that rotates the turntable 102, and an optical base 104. The optical base 104 is mounted with an objective lens actuator 105 that drives the two objective lenses 110 and 111 and a plurality of light sources (not shown) such as semiconductor lasers. The optical base 104 is supported by a pair of parallel feed shafts 106a and 106b so as to be movable in the radial direction of the optical disc 101, and is moved so as to be movable in the radial direction of the optical disc 101 by a mechanism (not shown). The objective lens actuator 105 on the optical base 104 is covered with a protective cover 107 having an opening 107a. Each component mounted on the optical base 104 constitutes an optical head.

  In FIG. 1, the direction orthogonal to the surface of the optical disc 101 (that is, the direction of the rotation axis of the spindle motor 103) is defined as the Z-axis direction. Further, the radial direction of the optical disc 101 is defined as the X-axis direction. A direction perpendicular to both the X-axis direction and the Z-axis direction is taken as a Y-axis direction. Also in other drawings, the X-axis direction, the Y-axis direction, and the Z-axis direction indicate the directions defined in FIG.

  For convenience of explanation, the direction from the objective lenses 110 and 111 toward the optical disc 101 in the Z-axis direction is defined as the upper direction, and the opposite direction is defined as the lower direction. The X-axis direction is the left-right direction, and the Y-axis direction is the front-rear direction. These directions are used only for convenience of explanation, and do not limit the orientation of the optical disc apparatus when used.

  As shown in FIG. 2, the objective lens actuator 105 includes a lens holder (holder) 112 that holds the objective lenses 110 and 111. The objective lenses 110 and 111 focus the light beams 108 and 109 emitted from a light source such as a semiconductor laser (not shown) mounted on the optical base 104 (FIG. 1) on the optical disc 101, respectively. The light beam 108 is, for example, a light beam having a wavelength of about 405 nm emitted from a blue semiconductor laser. The luminous flux 109 is, for example, a red luminous flux having a wavelength of around 660 nm emitted from a two-wavelength semiconductor laser and an infrared luminous flux having a wavelength of around 780 nm.

  The objective lens 110 is, for example, an objective lens for BD (Blu-Ray Disc). The objective lens 111 is, for example, a CD (Compact Disc) and a DVD (Digital Versatile Disc) compatible bifocal objective lens. These objective lenses 110 and 111 have different specifications such as an outer diameter, a focal length, and an operating distance (working distance).

  The lens holder 112 is made of a lightweight and highly rigid plastic such as a liquid crystal polymer. The lens holder 112 has two surfaces perpendicular to the Z-axis direction (here, upper and lower surfaces), two side surfaces perpendicular to the X-axis direction (here, left and right side surfaces), and two side surfaces perpendicular to the Y-axis direction (here, And has a substantially rectangular parallelepiped shape. In the lens holder 112, the objective lenses 110 and 111 are arranged such that their optical axes are parallel to the Z-axis direction and the line segment connecting the centers of the optical axes coincides with the X-axis direction (radial direction of the optical disc 101). It is fixed to. Furthermore, the objective lenses 110 and 111 are fixed so that they protrude from the upper surface of the lens holder 112 facing the optical disk 101 to the optical disk 101 side (here, the upper side) and have different heights in the Z-axis direction. ing.

  In the present embodiment, among the objective lenses 110 and 111, the BD objective lens 110 with a shorter moving distance is arranged so that the distance from the optical disc 101 is closer (that is, on the upper side). In addition, since BD is a specification for reading and writing information on the inner circumference side of the optical disc 101 more than CD and DVD, in order to facilitate reading and writing of information on the inner circumference side of the optical disc 101, The objective lens 110 for BD is arranged on the inner peripheral side of the optical disc 101 with respect to the objective lens 111 for CD / DVD.

  Here, the lens holder 112 has lens frame portions 112A and 112B for holding the objective lenses 110 and 111, respectively, on the upper side (side facing the optical disc 101). Of the both end faces in the X-axis direction of the lens frame portion 112A, the side face 112a facing the turntable 102 is formed so that the position in the X-axis direction is substantially the same position as the outer peripheral end face of the objective lens 110. The side surface 112a is formed with a notch 112b, and a part of the outer peripheral end surface of the objective lens 110 is exposed from the notch 112b.

  A pair of cylindrical protectors (buffer means, buffer members) 113a and 113b are attached to the lens frame portion 112A of the lens holder 112. The protectors 113a and 113b are formed of a resin having excellent wear resistance and lubricity, such as polyacetal resin (POM), and having a lower hardness than the turntable 102 and the optical disc 101.

  The protectors 113a and 113b are bonded to the lens frame 112A (that is, in the vicinity of the objective lens 110) so as to protrude slightly above (on the optical disc 101 side) the upper surface of the objective lens 110 having a short operating distance among the objective lenses 110 and 111. It is fixed by. The protector 113a is disposed at a position deviated from a straight line connecting the center of the objective lens 110 and the center of the turntable 102 (FIG. 1), and protrudes from the side surface 112a of the lens frame 112A toward the turntable 102. The protector 113a has a length in the Z-axis direction such that the cylindrical surface thereof faces the outer peripheral end surface (side surface) of the turntable 102 regardless of the position of the lens holder 112 in the Z-axis direction.

  In the objective lens frame 112A, for example, the protector 113b is disposed at a position symmetrical to the protector 113a with the optical axis of the objective lens 110 as the center. The protector 113b may be provided at another location. Moreover, the structure which provided only the protector 113a without providing the protector 113b is also possible.

  As shown in FIG. 3, a rectangular hole 112c is formed at the center of one side wall of the lens holder 112 in the Y-axis direction. Inside this hole 112c, two focusing coils (drive means) 114a and 114b wound continuously so that the winding axis direction coincides with the Z-axis direction, and the winding axis direction coincides with the Z-axis direction. A tilt coil 116 wound in this manner is inserted and fixed. Further, two tracking coils (driving means) 115a and 115b continuously wound so that the winding axis direction coincides with the Y axis direction are fixed to both side walls in the Y axis direction of the lens holder 112 by adhesion. Yes.

  A pair of movable part side substrates 117a and 117b are fixed to both side walls of the lens holder 112 in the X-axis direction. FIG. 3 shows only the movable portion side substrate 117a on the near side. The end lines of the focusing coils 114a and 114b, the tracking coils 115a and 115b, and the tilt coil 116 are soldered to the pair of movable portion side substrates 117a and 117b. An opening is formed on the upper surface of the lens holder 112 so as to correspond to the objective lenses 110 and 111. Further, the lower surface of the lens holder 112 is opened, and the light beam 108 emitted from the optical base 104 side described above. 109 (FIG. 2) enters the objective lenses 110 and 111 through the inner side (hollow part) of the windings of the focusing coils 114a and 114b.

  Further, on both side walls of the lens holder 112 in the X-axis direction, when the lens holder 112 moves in the X-axis direction, claw portions that come into contact with both side surfaces of a magnet 120a to be described later and restrict the movable range of the lens holder 112 112d and 112e are protruded.

  The lens holder 112, the objective lenses 110 and 111, the focusing coils 114a and 114b, the tracking coils 115a and 115b, the tilt coil 116, the movable part side substrates 117a and 117b, and the protectors 113a and 113b constitute a movable part unit 118.

  The objective lens actuator 105 has a base yoke 119 formed by pressing a magnetic material such as a cold rolled steel plate. The base yoke 119 is a plate-like member arranged so that the bottom surface thereof is parallel to the XY plane. The base yoke 119 also has a pair of inner yokes 119a and 119b that are erected in the Z-axis direction and face the Y-axis direction. The inner yokes 119a and 119b are centered in the width direction (X-axis direction). Has a slit.

  Magnets 120a and 120b are fixed to the inner yokes 119a and 119b, respectively. The magnets 120a and 120b are magnetized in the Y-axis direction, but are multipolarly magnetized so that the magnetization directions are opposite to each other with the center in the X-axis direction interposed therebetween. The magnets 120a and 120b are fixed so that the same poles face each other with the inner yokes 119a and 119b interposed therebetween. The magnets 120a and 120b and the base yoke 119 (inner yokes 119a and 119b) constitute a magnetic circuit. For example, a substantially rectangular parallelepiped gel holder 122 is bonded and fixed to the base yoke 119. Fixed portion side substrates 121a and 121b are fixed to both side surfaces of the gel holder 122 in the X-axis direction, respectively. Note that FIG. 3 shows only the front fixed portion side substrate 121a.

  The base yoke 119, the magnets 120a and 120b, the gel holder 122, and the fixed part side substrates 121a and 121b constitute a fixed part unit 123.

  A total of six wires 124a to 124f are attached in parallel to each other on the pair of movable part side substrates 117a and 117b fixed to both side walls of the lens holder 112, three on each substrate. Each of the wires 124a to 124f is an elastic body having conductivity, and one end of each of the wires 124a to 124f is fixed to the movable portion side substrates 117a and 117b by soldering. The other end of each of the wires 124a to 124f is fixed to the fixing portion side substrates 121a and 121b fixed to both side surfaces of the gel holder 122 by soldering. The wires 124a to 124f are electrically connected to the focusing coils 114a and 114b, the tracking coils 115a and 115b, and the tilt coil 116 by a combination of arbitrary two wires.

  Three groove portions are formed side by side in the Z-axis direction on both sides in the X-axis direction of the gel holder 122 (on the fixed portion side substrates 121a and 121b side), and each groove portion covers the vicinity of the roots of the wires 124a to 124f. In this way, ultraviolet curable gel dampers 125a and 125b are filled.

  With such a configuration, the movable unit 118 is moved in the Z-axis direction (focusing direction), the X-axis direction (tracking direction), and the Y-axis rotation direction (tilt direction) by the fixed unit 123 via the wires 124a to 124f. It is elastically supported to be movable.

  Note that the inner yokes 119a and 119b described above are provided in the inner portions (holes in the Z-axis direction) of the windings of the focusing coils 114a and 114b and the inner portions (windings in the Z-axis direction) of the windings of the tilt coil 116, respectively. Has been inserted. In this state, the tracking coils 115a and 115b are opposed to the magnets 120a and 120b.

  The operation of the objective lens actuator 105 configured as described above will be described. First, when controlling the focus deviation of the light spot, a predetermined two of the wires 124a to 124f are applied by applying a focus control voltage to a predetermined terminal (not shown) of the fixed part side substrates 121a and 121b. Currents are passed through the focusing coils 114a and 114b connected in series in the opposite directions. Due to the interaction between this current and the magnetic field generated by the magnets 120a and 120b, electromagnetic forces in the same Z-axis direction act on the focusing coils 114a and 114b, and the movable unit 118 moves in the Z-axis direction. . As a result, the objective lens moves perpendicularly to the surface of the optical disc 101, and the control of the defocus of the light spot is performed.

  When controlling the track deviation of the light spot, a track control voltage is applied to a predetermined terminal (not shown) of the fixed part side substrates 121a and 121b, thereby passing through a predetermined two of the wires 124a to 124f. Thus, a current is passed through the tracking coils 115a and 115b connected in series. Due to the interaction between this current and the magnetic field generated by the magnets 120a and 120b, the electromagnetic forces in the X-axis direction in the same direction act on the tracking coils 115a and 115b, and the movable unit 118 moves in the X-axis direction. . As a result, the objective lens moves in the radial direction (X-axis direction) of the optical disc 101, and the tracking deviation of the light spot is controlled.

  When controlling the radial tilt deviation of the light spot, a predetermined two of the wires 124a to 124f are applied by applying a tilt control voltage to predetermined terminals (not shown) of the fixed part side substrates 121a and 121b. Current is passed through the tilt coil 116. Due to the interaction between this current and the magnetic field generated by the magnets 120a and 120b, a moment in the rotation direction about the X axis is generated in the tilt coil 116, and the movable unit 118 rotates about the Y axis. As a result, the objective lens rotates about the Y axis. Thereby, even when the optical disc 101 is inclined in the radial direction (X-axis direction), the radial tilt control of the light spot is performed so that the optical axis of the objective lens is always perpendicular to the surface of the optical disc 101. Done.

  The movable unit 118 is elastically supported by six wires 124a to 124f so as to be movable in the Z-axis direction, the X-axis direction, and the Y-axis rotation direction. Therefore, in each operation described above, the movable unit 118 returns to the operation reference position in the Z-axis direction when the energization to the focusing coils 114a and 114b is released, and when the energization to the tracking coils 115a and 115b is released. Return to the operation reference position in the X-axis direction. When the energization of the tilt coil 116 is released, the operation reference position in the Y-axis rotation direction is restored.

  Further, since the vicinity of the roots of the six wires 124a to 124f is held in a state surrounded by the gel-like dampers 125a and 125b filled in the grooves of the gel holder 122, the movable unit 118 is vibrated. Attenuation characteristics are given. As a result, good focus control characteristics, track control characteristics, and radial tilt control characteristics are obtained, and unnecessary vibration from the outside is hardly transmitted to the movable unit 118. Further, when the movable unit 118 moves in the tracking control direction, any of the claw portions 112d and 112e of the lens holder 112 abuts on the side surface of the magnet 120a, so that the movable range of the movable unit 118 in the tracking direction is restricted. Is done.

  Next, the collision preventing action between the lens holder 112 and the turntable 102 by the protector will be described. 4 and 5 are a plan view and a front view showing a state in which the optical head is at the innermost circumferential position of the recording area of the optical disc 101. FIG. 6 and 7 are a plan view and a front view showing a state in which the movable unit 118 is further moved to the inner peripheral side of the optical disc 101 from the state shown in FIGS. 4 and 5.

  In the state shown in FIGS. 4 and 5, the optical head that moves in the radial direction of the optical disc 101 along the feed shafts 106 a and 106 b is located at the innermost peripheral position of the recording area of the optical disc 101. In this state, reading or writing of data at the innermost peripheral position of the recording area of the optical disc 101 is performed by the CD / DVD compatible objective lens 111 disposed on the outer peripheral side of the optical disc 101 among the objective lenses 110 and 111. . Further, the BD objective lens 110 disposed on the inner peripheral side of the optical disc 101 is located close to the outer peripheral end surface of the turntable 102.

  As described above, the movable part side substrate 117a and the wires 124a to 124c are provided on the side wall of the lens holder 112 on the turntable 102 side. The movable part side substrate 117a and the wires 124a to 124c are provided on the turntable. Since it faces the spindle motor 103 whose outer diameter is smaller than 102 (FIG. 5), the gap in this portion is wider than the gap between the objective lens 110 and the outer peripheral end surface of the turntable 102.

  The protector 113 a is fixed to the lens holder 112 so as to protrude from the outer peripheral end surface of the objective lens 110 toward the turntable 102 at a position deviated from a straight line connecting the optical axis of the objective lens 110 and the center of the turntable 102. . That is, the outer peripheral surface (cylindrical surface) of the protector 113a is in a position closest to the outer peripheral end surface of the turntable 102 in the movable unit 118.

  6 and 7, the movable unit 118 mounted on the optical head is further displaced toward the inner peripheral side (−X direction) of the optical disc 101 in the tracking direction. This state may occur when a higher voltage than usual is applied to the tracking coils 115a and 115b due to an abnormality in tracking control, or when a large vibration or impact is applied from the outside in the X-axis direction. Here, of the objective lenses 110 and 111, at least the optical axis center of the objective lens 110 closer to the turntable 102 moves in the radial direction of the optical disc 101 as the movable unit 118 moves in the tracking direction. To do.

  At this time, since the protector 113a contacts the outer peripheral end surface of the turntable 102, collision between the objective lens 110 or the lens holder 112 and the turntable 102 can be prevented. Further, since the protector 113a is made of a material having excellent wear resistance and lubricity, the protector 113a does not generate wear powder when it comes into contact with the turntable 102, and the objective lens actuator 105 due to wear powder or the like. Damage and deterioration of characteristics can be prevented. Furthermore, since the protector 113a is made of a material having a hardness lower than that of the turntable 102, the turntable 102 can be prevented from being damaged.

  In addition to the cases shown in FIGS. 4 to 7, in the process of attaching the optical base 104 to the feed shafts 106 a and 106 b and incorporating it in the mechanism part including the spindle motor 103 and the turntable 102, and the subsequent adjustment process, There is a possibility that the movable unit 118 and the turntable 102 collide with each other. However, even in such a case, the protector 113a provided in the lens holder 112 contacts the turntable 102, so that damage and characteristic deterioration of the objective lens actuator 105 can be prevented. Therefore, the assembly of the optical disk apparatus can be performed more easily and reliably.

  FIGS. 8A and 8B are schematic diagrams for explaining the difference in action and effect depending on the position of the protector. In FIG. 8A, reference numeral G1 indicates a gap between the objective lens 110 and the turntable 102 when the protector 113a is not provided. Reference G2 indicates a gap between the protector 113a and the turntable 102 in the present embodiment. In FIG. 8B, symbol G <b> 3 indicates a gap between the protector 113 a and the turntable 102 when the protector 113 a is arranged on a straight line connecting the optical axis of the objective lens 110 and the center of the turntable 102. .

  As shown in FIG. 8B, when the protector 113a is arranged on a straight line connecting the optical axis of the objective lens 110 and the center of the turntable 102, the gap between the protector 113a and the turntable 102 is reduced, and the contact frequency is reduced. However, there is a problem that the height becomes high or a sufficient gap cannot be secured. On the other hand, as shown in FIG. 8A, the protector 113a is arranged at a position shifted from a straight line connecting the optical axis of the objective lens 110 and the center of the turntable 102, thereby reducing the frequency of contact. be able to. In addition, when the movable unit 118 is not displaced to the inner peripheral side (−X direction) from the innermost peripheral position of the optical disc 101, a sufficient gap between the protector 113a and the turntable 102 can be secured. .

  Next, the collision preventing action between the objective lens and the optical disk by the protector will be described. FIG. 9 is a front view showing a state in which the movable unit 118 is displaced toward the optical disc 101 from the state shown in FIG. In this state, when focus pull-in fails, when a higher voltage than usual is applied to the focusing coils 115a and 115b due to an abnormality in focus control, or when a large vibration or impact is applied from the outside in the Z-axis direction. Can happen.

  The protectors 113a and 113b are arranged so as to protrude slightly above the upper surfaces (surfaces facing the optical disc 101) of the objective lenses 110 and 111 through the opening 107a of the protective cover 107 shown in FIG. . That is, in the movable unit 118, the upper surfaces of the protectors 113 a and 113 b are located closest to the optical disc 101. Therefore, as shown in FIG. 9, when the movable unit 118 moves to the optical disc 101 side, the protectors 113 a and 113 b come into contact with the optical disc 101 to prevent the objective lens 110 or the lens holder 112 from colliding with the optical disc 101. The protectors 113a and 113b are excellent in wear resistance and lubricity, and are made of a material having a lower hardness than the optical disk 101. Therefore, damage and characteristic deterioration of the objective lens actuator 105 due to wear powder or the like can be prevented. In addition, damage to the optical disk 101 can be prevented.

  In the first embodiment described above, the protectors 113a and 113b are molded separately from the lens holder 112 and fixed by adhesion. However, the protectors 113a and 113b may be outsert molded, or different materials may be used. You may integrally mold using the two-color molding which shape | molds simultaneously.

  The protectors 113a and 113b have a fluidity at the time of application, but after curing, a room temperature curing type silicone rubber resin (RTV rubber) having rubber-like elasticity, wear resistance and lubricity, or UV curing. You may comprise a type | mold silicon rubber-type resin.

  FIG. 10 is a perspective view showing the movable unit 118 when the protector is made of a fluid silicone rubber resin. FIG. 11 is a perspective view showing the movable unit 118 after the silicon rubber-based resin is cured. As shown in FIG. 10, on the side surface 112a on the turntable 102 side of the lens holder 112, a coating groove opened in the X-axis direction so that the resin does not flow out after the resin is applied and can maintain a uniform shape. 112f is formed. As the resin poured into the groove 112f is cured, protectors 113a and 113b are formed as shown in FIG. The protector 113a protrudes toward the turntable 102 from the outer peripheral end surface of the objective lens 110 in the X-axis direction, and the upper surfaces of the protectors 113a and 113b protrude from the upper surfaces of the objective lenses 110 and 111 toward the optical disc 101.

  As described above, in the present embodiment, the protector 113a protruding from the outer peripheral end surface of the objective lens 110 to the turntable 112 side is provided at a position facing the outer peripheral end surface of the turntable 102. Collision between the lens holder 112 and the turntable 102 can be prevented. As a result, an optical disc apparatus that can read / write information on the inner peripheral position of the optical disc 101 and has high reliability can be obtained.

  In addition, when the movable unit 118 is moved further in the inner circumferential direction from the innermost circumferential position of the recording area of the optical disc 101, the protector 113a comes into contact with the outer circumferential end surface of the turntable 102. However, it is possible to obtain a highly reliable optical disk apparatus that can prevent damage and characteristic deterioration of the objective lens actuator 105.

  Furthermore, since there is no possibility that the objective lens 110 or the lens holder 112 and the turntable 102 collide in the assembly process of the optical disk apparatus, the assembly work of the optical disk apparatus can be performed more easily and reliably.

  In addition, the gap between the protector 113a and the turntable 102 can be secured by disposing the protector 113a at a position shifted from the straight line connecting the center of the objective lens 110 and the center of the turntable 102.

  If the protectors 113a and 113b are formed integrally with the lens holder 112, the assembly process can be further simplified, and in addition, the positional accuracy of the protectors 113a and 113b with respect to the lens holder 112 can be increased.

  Further, the structure in which the protectors 113a and 113b protrude from the upper surfaces of the objective lenses 110 and 111 to the optical disc 101 side prevents the objective lenses 110 and 111 from colliding with the optical disc 101. A highly reliable optical disc apparatus that can prevent damage and characteristic deterioration of the objective lens actuator 105 can be obtained. Further, by providing the protector 113b in addition to the protector 113a, the impact at the time of contact with the optical disc 101 can be dispersed.

  In addition, by forming a groove 112f on the side surface of the lens holder 112 and applying a silicone rubber-based resin, the protectors 113a and 113b are formed, thereby forming a protector 113a and a uniform shape excellent in elasticity. 113b can be obtained by a simple method.

Embodiment 2. FIG.
12 and 13 are an exploded perspective view and a perspective view showing the movable unit of the optical disc apparatus according to Embodiment 2 of the present invention. 12 and 13, the same reference numerals are given to the same or corresponding components as those of the first embodiment.

  As shown in FIGS. 12 and 13, the movable unit in the second embodiment includes four objective lenses 110 and 111 around the objective lens 110 having a short operating distance and disposed on the inner peripheral side of the optical disc 101. It has a protector 113 having two protrusions 113a, 113b, 113c, 113d. The protector 113 is formed by forming cylindrical projections 113a to 113d at four corners of a substantially rectangular frame portion, and forming an attachment hole 113e for attaching the objective lens 110 at the center of the frame portion. A spherical surface 113f having a spherical surface centered around the principal point of the objective lens 110 attached to the attachment hole 113e is provided below the protector 113 (on the side opposite to the optical disc 101 side). The protector 113 is made of a resin such as polyacetal resin (POM) that has excellent wear resistance and lubricity, and has a lower hardness than the turntable 102 and the optical disc 101.

  A conical surface 112 f in contact with the spherical surface portion 113 f of the protector 113 is formed on the lens frame portion 112 </ b> A of the lens holder 112. On this conical surface 112f, a protector 113 to which the objective lens 110 is attached is placed and fixed so as to be able to adjust the tilt around the principal point of the objective lens 110.

  Of the protrusions 113 a to 113 d of the protector 113, the protrusions 113 a and 113 c are arranged to face the outer peripheral end surface of the turntable 102, and further turntable 102 than the outer peripheral end surface of the objective lens 110 on the turntable 102 side. It is arranged at a position protruding to the side. In addition, the protrusions 113 a and 113 c are both arranged at positions shifted from a straight line connecting the center of the objective lens 110 and the center of the turntable 102. The other protrusions 113b and 113d are arranged at positions protruding from the outer peripheral end surface of the objective lens 110 in the direction opposite to the protrusions 113a and 113c. The protrusions 113a to 113d protrude further upward (on the optical disc 101 side) than the upper surfaces of the objective lenses 110 and 111.

  Next, assembly of the movable unit 118 will be described. Here, it is assumed that the focusing coils 114a and 114b, the tracking coils 115a and 115b, the tilt coil 116, and the movable part side substrates 117a and 117b are already fixed to the lens holder 112 by bonding. First, the objective lens 111 is fixed to the lens frame portion 112B of the lens holder 112 by bonding without adjusting the optical axis. Next, the protector 113 to which the objective lens 110 is fixed is placed on the conical surface 112 f of the lens holder 112. Next, using an inclination measuring means such as an autocollimator (not shown), the inclination between the edge surface (surface perpendicular to the optical axis) of the objective lens 111 and the edge surface of the objective lens 110 is measured, and the protector is adjusted so that the inclinations coincide. After adjusting 113 along the conical surface 112f, the protector 113 is fixed to the lens holder 112 by adhesion. In this way, the objective lenses 110 and 111 are fixed to the lens holder 112 so that both optical axes are parallel, and the movable unit 118 is assembled. Other configurations and operations are the same as those in the first embodiment.

  When the movable unit 118 is further displaced from the innermost circumferential position of the recording area of the optical disc 101 toward the inner circumferential side (−X direction), the projections 113 a and 113 c of the protector 113 come into contact with the outer circumferential end surface of the turntable 102. Therefore, collision between the objective lens 110 and the lens holder 112 and the turntable 102 can be prevented. In addition, the protector 113 is excellent in wear resistance and lubricity, and is formed of a material having a hardness lower than that of the turntable 102. Therefore, the protector 103 and the turntable 102 come into contact with the turntable 102 and the turntable 102. There will be no damage or characteristic deterioration of the objective lens actuator 105.

  When the movable unit 118 is displaced to the optical disc 101 side (+ Z direction), the upper surfaces of the projections 113a, 113b, 113c, and 113d of the protector 113 are in contact with the optical disc 101, so that the objective lens 110 and the lens holder 112 A collision with the optical disc 101 can be prevented. Further, the protector 113 is excellent in wear resistance and lubricity, and is formed of a material having a hardness lower than that of the optical disc 101. Therefore, damage to the optical disc 101 due to contact between the protector 103 and the optical disc 101, and an objective are also obtained. The lens actuator 105 is not damaged or deteriorated in characteristics. In addition, since the four portions of the protrusions 113a to 113d are in contact with the optical disc 101, the impact at the time of contact can be dispersed.

  Further, the protector 113 is made of a resin molded product having a spherical surface centered around the principal point of the objective lens 110, and the objective lens 110 is attached to the lens holder 112 via the protector 113. In the assembly process, the optical axes of the objective lenses 110 and 111 can be matched by a simple method. That is, it is possible to obtain a highly reliable optical disc apparatus in which the objective lenses 110 and 111 and the lens holder 112 do not collide with the turntable 102 and the optical disc 101 while improving the assemblability.

  In the first embodiment described above, two protectors 113a and 113b are used. In the second embodiment, the protector has four protrusions 113a to 113d, but the number of protectors (protrusions) is any number. It may be.

  In the first and second embodiments described above, the optical disk apparatus configured to elastically support the lens holder 112 using a wire has been described. However, the present invention supports the lens holder so as to be rotatable about a support shaft, for example. You may apply to the optical disk apparatus of the structure which carries out.

  As an application example of the present invention, the present invention can be applied to an optical disc apparatus such as a BD player, a BD recorder, an HD-DVD player, and an HD-DVD recorder.

It is a perspective view which shows the principal part of the optical disk apparatus in Embodiment 1 of this invention. 2 is a perspective view showing an objective lens actuator of an optical head in the optical disc apparatus in Embodiment 1. FIG. FIG. 3 is an exploded perspective view showing an objective lens actuator of an optical head in the optical disc apparatus in the first embodiment. It is a top view which shows the state which has an optical head in the innermost peripheral position of an optical disk. It is a front view which shows the state in which the optical head is located in the innermost periphery position of an optical disk. It is a top view which shows the state which the movable part unit moved further to the inner peripheral side from the state shown in FIG. It is a front view which shows the state which the movable part unit moved further to the inner peripheral side from the state shown in FIG. It is a schematic diagram for demonstrating the difference of the effect by the position of a protector. FIG. 5 is a front view showing a state where the movable unit is displaced to the optical disc side from the state shown in FIG. 4. It is a perspective view which shows a movable part unit in case a protector is comprised with fluid silicone rubber-type resin. It is a perspective view which shows the movable part unit after the silicone rubber-type resin shown in FIG. 10 hardened | cured. It is a disassembled perspective view which shows the movable part unit of the optical disk apparatus based on Embodiment 2 of this invention. It is a perspective view which shows the movable part unit of the optical disk apparatus based on Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 Optical disk, 102 Turntable, 103 Spindle motor, 104 Optical base, 105 Objective lens actuator, 106a, 106b Feed axis, 107 Protective cover, 108, 109 Light flux, 110, 111 Objective lens, 112 Lens holder, 113 Protector, 113a- 113d Projection part, 114a, 114b Focusing coil, 115a, 115b Tracking coil, 116 Tilt coil, 117a, 117b Movable part side substrate, 118 Movable part unit, 119 Base yoke, 120a, 120b Magnet, 121a, 121b Fixed part side substrate, 122 gel holder, 123 fixing unit, 124a-124f wire, 125a, 125b damper.

Claims (14)

A plurality of objective lenses for focusing the light flux on the optical disc;
A holder for holding the objective lens;
An optical head having driving means for driving the holder in a tracking direction that is a substantially radial direction of the optical disc and a focusing direction that is substantially perpendicular to the surface of the optical disc;
A turntable for holding and rotating the optical disc,
The optical disk apparatus according to claim 1, wherein in the holder, a buffer means that protrudes toward the turntable from the outer peripheral end surface of the objective lens is disposed at a position facing the outer peripheral end surface of the turntable.   When the optical head is at the innermost peripheral position of the recording area of the optical disc and the holder moves in the inner peripheral direction of the optical disc in the tracking direction, the buffer means is placed on the outer peripheral end surface of the turntable. The optical disk apparatus according to claim 1, wherein the optical disk apparatus is in contact. Of the plurality of objective lenses, the optical axis center of the first objective lens located closest to the turntable moves in the radial direction of the optical disc as the holder moves in the tracking direction,
3. The optical disc apparatus according to claim 1, wherein the buffer means is disposed at a position deviated from a straight line connecting the first objective lens and the center of the turntable.   4. The optical disc apparatus according to claim 1, wherein the buffer means protrudes further toward the optical disc side than a surface of the plurality of objective lenses on the optical disc side. 5.   5. The optical disc apparatus according to claim 1, wherein the buffer means is formed integrally with the holder.   5. The buffering means according to claim 1, wherein the buffer means is made of a silicone rubber resin, and is disposed in a groove formed on a surface of the holder facing the turntable. The optical disc device according to any one of the above.   5. The shock absorber has a spherical surface centered around the principal point of the objective lens, and the objective lens is attached to the holder via the shock absorber. The optical disc device according to any one of the above. An optical head for recording or reproducing information on an optical disk held on a turntable,
A plurality of objective lenses for condensing a light beam on the optical disc;
A holder for holding the objective lens;
Driving means for driving the holder in a tracking direction that is a substantially radial direction of the optical disc, and a focusing direction that is substantially perpendicular to the surface of the optical disc,
An optical head characterized in that, in the holder, a buffer means protruding from the outer peripheral end surface of the objective lens to the turntable side is arranged at a position facing the outer peripheral end surface of the turntable.   When the optical head is at the innermost peripheral position of the recording area of the optical disc and the holder moves in the inner peripheral direction of the optical disc in the tracking direction, the buffer means is placed on the outer peripheral end surface of the turntable. The optical head according to claim 8, wherein the optical head is in contact. Of the plurality of objective lenses, the optical axis center of the first objective lens located closest to the turntable moves in the radial direction of the optical disc as the holder moves in the tracking direction,
10. The optical head according to claim 8, wherein the buffer means is disposed at a position deviated from a straight line connecting the first objective lens and the center of the turntable.   11. The optical head according to claim 8, wherein the buffer means protrudes further to the optical disc side than a surface on the optical disc side of the plurality of objective lenses.   12. The optical head according to claim 8, wherein the buffer means is formed integrally with the holder.   12. The buffering means according to claim 8, wherein the buffer means is made of a silicone rubber-based resin and is disposed in a groove formed on a surface of the holder facing the turntable. The optical head according to any one of the above.   12. The buffering means has a spherical surface centered around the principal point of the objective lens, and the objective lens is attached to the holder via the buffering means. The optical head according to any one of the above.

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