JP4530073B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus that records and / or reproduces data with respect to an optical disc for high-density recording such as a braille disc, and more particularly to an objective lens protection structure of the optical pickup.

  In recent years, a Blu-ray Disc has been put to practical use as an optical disc for high-density recording. In an optical disc device compatible with such a Blu-ray disc (hereinafter referred to as BD), in order to be compatible with a conventional CD (Compact Disc) and DVD (Digital Versatile Disc), an optical disc compatible with BD is used. System and two objective lenses, CD and DVD compatible optical systems, are mounted on an optical pickup (see Patent Document 1).

  On the other hand, the objective lens can move in the direction of its optical axis. When vibration is applied from the outside, it moves greatly toward the optical disc when focusing is started, and the surface of the objective lens and the lens barrel come into contact with the optical disc. there's a possibility that. Alternatively, the optical disk may be loaded in a tilted state and rotated as it is. For this reason, it has been proposed to provide a protective member that protrudes closer to the optical disc side than the surface of the objective lens and the lens barrel in the vicinity of the objective lens so that the surface of the objective lens and the lens barrel do not directly contact the optical disc. (See Patent Document 2).

  FIG. 5 shows a conventional objective lens protection structure disclosed in Patent Document 2. As shown in FIG. The protection member 50 is formed of, for example, a silicon rubber, other rubber materials, an aggregate material such as a felt material, or a laminated material of a rubber material and a synthetic resin, and has a rectangular parallelepiped shape. On the surface 52 of the movable base 51 of the optical pickup that faces the surface 61 of the optical disk 60, locking protrusions 53 and 54 that protrude toward the optical disk 60 are formed in the radial direction of the optical disk 60. The bottom surface of the protective member mounting region 55 between the portions 53 and 54 is formed as an inclined surface so that the downstream side in the rotation direction of the optical disk 60 is high and the upstream side is low.

  When the protective member 50 is bonded to the protective member mounting region 55 between the locking projections 53 and 54, the end 56 on the downstream side in the rotation direction of the optical disc 60 and the surface of the optical disc 60 among the end portions on the upper surface of the protective member 50. The distance to 61 is shorter than the distance between the upstream end 57 in the rotation direction of the optical disc 60 and the surface 61 of the optical disc 60. If the protective member 50 is attached in an inclined state in this way, even if the protective member 50 comes into contact with the surface 61 of the optical disc 60, the upstream end 57 of the protective member 50 ends 56 and 57. Since it contacts the surface 61 of the optical disc 60 on the downstream end portion 56 side where the inclination angle is smaller than the edge, damage to the optical disc 60 can be prevented or reduced.

In the conventional objective lens protection structure, as one of the reasons for making the protection member 50 cubic, it is conceivable that the direction of the protection member 50 need not be taken into consideration in the assembly process of the optical pickup. Then, it is good if it is made of a single material such as rubber material or felt material, but if it is made of laminated material, the direction of each laminated material is important, and assembly workability is important. May be reduced. In addition, it is difficult to accurately form a minute rectangular parallelepiped using a rubber material, a felt material, or the like as the protection member 50, which causes an increase in cost. Further, since the protective member mounting area 55 on which the protective member 50 is mounted is sandwiched between the locking projections 53 and 54, it is difficult to form the inclination of the bottom surface of the protective member mounting area 55 with high accuracy, and The mold structure for resin molding becomes complicated, which increases the cost. Furthermore, it is difficult to mount the protection member with high accuracy to the protection member mounting region 55 sandwiched between the locking protrusions 53 and 54.
JP 2001-67700 A JP 2004-303383 A

  The present invention has been made in order to solve the above-described problems of the conventional example, and an object thereof is to provide an optical disc apparatus having an objective lens protection structure for an optical pickup that is low in cost and easy to assemble. .

In order to achieve the above object, the invention of claim 1
Two objective lenses arranged in the tangential direction with respect to the optical disc, each having a different numerical aperture;
Two protective members arranged in a radial direction of the optical disc and arranged substantially symmetrically with respect to a line connecting the optical axes of the two objective lenses;
An optical disc apparatus including an optical pickup including a movable base that holds the two objective lenses and the two protective members,
In a state where the surface of the optical disc and the optical axis of the objective lens are orthogonal, the protective member mounting area of the movable base is an inclined surface so that the downstream side is higher and the upstream side is lower than the rotation direction of the optical disc. Formed,
When the protective member is mounted only on at least a part of the downstream end in the rotation direction of the optical disc, the outer peripheral end in the radial direction of the optical disc, and the inner peripheral end in the protective member mounting region of the movable base. A locking projection that serves as a guide is formed.
The protective member has a sheet shape whose thickness is smaller than that of each part having the smallest size on the bottom surface, and the thickness protrudes from the surface of the protective member mounting region of the movable base of the locking protrusion. An objective lens protection structure for an optical pickup is provided, wherein the objective lens protection structure is formed of a material having a hardness larger than that of the movable base and less than that of the movable base material.

  According to a second aspect of the present invention, there is provided the optical disk apparatus according to the first aspect, wherein the surface of the optical disk and the optical axis of the objective lens are orthogonal to each other with respect to the rotation direction of the optical disk in the protective member mounting region of the movable base. The inclination angle is 3 degrees or more and 10 degrees or less.

  According to a third aspect of the present invention, in the optical disc apparatus according to the first or second aspect, the protective member is rectangular in plan view.

  According to a fourth aspect of the present invention, in the optical disc according to the third aspect, the locking projection is opposed to an objective lens positioned on the downstream side in the rotation direction of the optical disc among the four corners in plan view of the protection member. It includes a portion formed in a substantially L shape so as to guide a corner to be turned.

  According to the first aspect of the present invention, the protective member is in the form of a sheet having a thickness smaller than that of the smallest part of the bottom surface, and the thickness of the movable base protective member mounting region of the locking protrusion. Since it is made of a material that is larger than the amount of protrusion from the surface and less hard than the material of the movable base, for example, a tape made of a soft material can be used, compared with the protective member of the conventional example. Manufacturing cost can be reduced. If an adhesive or the like is applied to one surface of the protective member, the step of applying the adhesive to the protective member mounting region of the movable base can be omitted. Furthermore, the locking protrusions are provided only at at least a part of the downstream end in the rotation direction of the optical disc in the protective member mounting area of the movable base, the outer peripheral end in the radial direction of the optical disc, and the inner peripheral end. Therefore, the protection member mounting area of the movable base is not sandwiched between the protection protrusions in the rotation direction of the optical disc. Therefore, when the protective member is mounted in the protective member mounting region, the protective member is positioned in the rotation direction of the optical disk by applying the tip of the protective member to the engaging protrusion at the downstream end in the rotation direction of the optical disk. This makes it easy to mount the protective member. Further, since the locking protrusion is not provided at the upstream end of the rotation direction of the optical disc, even if the optical disc is tilted and rotated, only the edge portion of the protective member contacts the surface of the optical disc. Damage can be prevented or reduced. Further, since the locking projection is not provided at the upstream end in the rotation direction of the optical disc, the structure of the mold can be simplified when the movable base is formed by resin molding, and the protective member mounting area Tolerance management of the tilt angle becomes easy.

  According to the invention of claim 2, by setting the inclination angle of the protective member mounting area of the movable base with respect to the rotation direction of the optical disc to 3 degrees or more and 10 degrees or less, the downstream end portion and the upstream of the rotation direction of the optical disk of the protection member One of the edges of the side end portion does not become steeper than the other, and the balance of the buffering effect by the edges of the downstream end portion and the upstream end portion can be maintained.

  According to the invention of claim 3, since the protective member is rectangular in plan view, positioning with respect to the protective member mounting region can be performed while any one of the four sides of the protective member is brought into contact with the locking projection. The mounting operation of the protective member becomes easy and the positioning accuracy can be increased.

  According to the fourth aspect of the present invention, the locking projection is substantially L so as to guide the corner facing the objective lens located downstream in the rotation direction of the optical disc among the four corners in plan view of the protection member. Therefore, even if the adhesive protrudes when the objective lens is fixed, the possibility that the adhesive adheres to the protective member is reduced. As a result, it is possible to reduce the possibility that the optical disk is damaged by the adhesive that has adhered to the protective member and solidified.

  An optical disc apparatus according to an embodiment of the present invention will be described. This optical disc is compatible with high-density recording optical discs such as Blu-ray discs and conventional optical discs such as CD and DVD, and the optical pickup is an optical system compatible with BD and optical compatible with CD and DVD. Has a system.

  FIG. 1 shows an optical system in an optical pickup of an optical disc apparatus according to this embodiment. The optical pickup 1 includes a main body 100 and an objective lens actuator 200 attached to the main body 100. Further, the optical pickup 1 includes a first optical system 10 for recording / reproducing an optical disk that has been widely used conventionally, such as a CD or a DVD, and a recording / reproducing of an optical disk for high-density recording, such as a BD. And a second optical system 20 for performing the above. The objective lens actuator 200 holds objective lenses 17 and 27 provided in the first optical system 10 and the second optical system 20, respectively. The main body 100 is configured, for example, by fixing other constituent members of the first optical system 10 and the second optical system 20 on a base member 101 made of hard resin. The above-mentioned CD includes CD-ROM, CD-R, CD-RW, etc., and DVD includes DVD-ROM, DVD-R, DVD + R, DVD-RW, DVD + RW, DVD-RAM, etc. The BD includes a BD-ROM, a BD-R, a BD-RE, and the like.

  The first optical system 10 includes an infrared laser element 11a, a red laser element 11b, a dichroic prism 12, a beam splitter 13, a collimator lens 14, a mirror 15, a quarter wavelength plate 16, and a first objective. A lens 17, a condenser lens 18, and a photodetector 19 are provided. The second optical system 20 includes a blue laser element 21, a beam splitter 23, a collimator lens 24, a mirror 25, a quarter wavelength plate 26, a second objective lens 27, a condenser lens 28, And a photodetector 29.

  The infrared laser element 11a emits an infrared laser beam having a wavelength of about 780 nm, and is used for CD recording / reproduction. The red laser element 11b emits a red laser beam having a wavelength of about 650 nm, and is used for DVD recording / reproduction. The dichroic prism 12 is a prism that transmits light with a wavelength in the infrared region and reflects light with a wavelength in the red region. The laser beam emitted from the element 11 b is reflected by the reflecting surface of the dichroic prism 12. The optical path of the laser beam emitted from the red laser element 11a is substantially the same as the optical path of the laser beam emitted from the infrared laser element 11a in the portion after the dichroic prism 12.

  On the other hand, the blue laser element 21 emits a blue laser beam having a wavelength of about 405 nm and is used for BD recording / reproduction. The second optical system 20 is not provided with a laser element in addition to the blue laser element 21, and is not provided with a member corresponding to the dichroic prism 12.

  The beam splitters 13 and 23 are optical elements that transmit or reflect the incident laser beam according to the polarization direction. A laser beam (for example, P-polarized light) emitted from the infrared laser element 11 a, the red laser element 11 b, or the blue laser element 21 passes through the beam splitters 13 and 23. On the other hand, a laser beam (for example, S-polarized light) reflected by the recording surface of the optical disc 2 and incident on the beam splitters 13 and 23 is reflected by the beam splitters 13 and 23. The beam splitters 13 and 23 are positioned and fixed to the base member 101 so as to reflect the incident laser beam reflected by the recording surface of the optical disc 2 toward the photodetectors 19 and 29.

  The collimator lenses 14 and 24 make the laser beam, which is the diffused light emitted from the infrared laser element 11a, red laser element 11b, or blue laser element 21, which is a point light source, parallel light. The laser beams emitted from the collimator lenses 14 and 24 are reflected by the mirrors 15 and 25, respectively, in a direction orthogonal to the incident direction, that is, a direction orthogonal to the recording surface of the optical disc 2. The reflected laser beam is transmitted through quarter-wave plates 16 and 26 that use linearly polarized light as circularly polarized light and circularly polarized light as linearly polarized light.

  The first objective lens 17 and the second objective lens 27 have different numerical apertures according to the wavelengths of the laser elements 11a, 11b, and 21, which are light sources, and are composed of, for example, aspheric lenses. The first objective lens 17 condenses the infrared laser beam on the CD recording surface and condenses the red laser beam on the DVD recording surface. That is, the first objective lens 17 converges the infrared laser beam and the red laser beam, and irradiates the CD and DVD recording surfaces as laser spots, respectively. On the other hand, the second objective lens 27 focuses the blue laser beam on the recording surface of the BD. That is, the second objective lens 27 converges the blue laser beam and irradiates the recording surface of the BD as a laser spot. In the present embodiment, the second objective lens 27 is configured separately from the first objective lens 17.

  As described above, the laser beam irradiated and reflected from the first objective lens 17 or the second objective lens 27 on the recording surface of the optical disc 2 passes through the first objective lens 17 or the second objective lens and is ¼. The light enters the wave plates 16 and 26. At this time, the reflected laser beam is converted from circularly polarized light to linearly polarized light. The polarization direction of the laser beam is the polarization direction of the laser beam emitted from the infrared laser element 11a, the red laser element 11b, or the blue laser element 21. (Eg, P-polarized light) That is, light directed from the quarter-wave plates 16 and 26 to the mirrors 15 and 25 is, for example, S-polarized light, and enters the beam splitters 13 and 23 from the quarter-wave plates 16 and 26 via the mirrors 15 and 25, respectively. The laser beam to be reflected is reflected by the beam splitters 13 and 23 without being transmitted. The laser beams reflected by the beam splitters 13 and 23 enter the photodetectors 19 and 29 via the condenser lenses 18 and 28, respectively. The photodetectors 19 and 29 detect that a laser beam has been incident and output it as an electrical signal that can be used during recording / reproduction of the optical disc 2.

  Next, the objective lens protection structure of the optical pickup of the optical disc apparatus in the present embodiment will be described. As shown in FIG. 2, the first objective lens 17 or the second objective lens 27 is arranged in the tangential direction (T direction) with respect to the optical disc 2, and is arranged on the movable base (lens holder) 201 of the objective lens actuator 200. Is retained. The protection member 30 is disposed in two radial positions (R direction) of the optical disc 2 and approximately symmetrically with respect to a line connecting the optical axes of the two objective lenses 17 and 27. 27 and the movable base 201.

  In the state where the surface 2a of the optical disc 2 and the optical axes of the first objective lens 17 or the second objective lens 27 are orthogonal to each other, as shown in FIG. It is formed as an inclined surface so that the downstream side (202a) is higher and the upstream side (202d) is lower than the rotation direction of the optical disc 2. Further, around the protective member mounting area 202 of the movable base 201, there are a downstream end 202 a in the rotation direction (T direction) of the optical disc 2, an outer peripheral end portion 202 b in the radial direction (R direction) of the optical disc 2 and the inner end. Locking projections 203 serving as a guide when the protective member 30 is mounted are formed only on at least a part of the three sides of the circumferential end 202c. That is, no locking protrusion is provided at the upstream end 202d in the rotation direction (T direction) of the optical disc 2 in the periphery of the protective member mounting area 202. The arrangement of the locking projection 203 will be described later.

  The protection member 30 has a rectangular shape in plan view, is a sheet shape whose thickness is smaller than the shorter one of the width and the length thereof, and the thickness is attached to the protection member of the movable base 201 of the locking projection 203. It is made of a material that is larger than the protruding amount from the surface of the region 202 and has a lower hardness than the material of the movable base 201, for example, a rubber material such as silicon rubber, or other soft materials. Moreover, it is preferable that the protection member 30 is cut | disconnected from the tape-shaped thing by which the adhesive agent etc. were apply | coated to the one surface (back surface).

  In addition, the tolerance management of the inclination angle of the protection member mounting area 202 is maintained while maintaining the balance of the buffering effect by the edges of the downstream end 30a and the upstream end 30b in the rotation direction (R direction) of the optical disk 2 of the protection member 30. When the surface of the optical disc 2 and the optical axes of the objective lenses 17 and 27 are orthogonal to each other, the rotation direction of the optical disc in the protective member mounting area 202 of the movable base 201, that is, the surface of the optical disc 2 is considered. The inclination angle θ with respect to 2a is preferably 3 ° or more and 10 ° or less.

  Thus, for example, a tape made of a soft material can be used as the protection member 30, and the manufacturing cost can be reduced as compared with the protection member 50 of the conventional example. Furthermore, if an adhesive or the like is applied to one surface of the protective member 30, the step of applying the adhesive to the protective member mounting region 202 of the movable base 201 can be omitted. The locking projection 203 includes a downstream end 202a in the rotation direction (T direction) of the optical disc 2 in the protective member mounting area 202 of the movable base 201, and an outer peripheral end 202b in the radial direction (R direction) of the optical disc 2. And the optical disk 2 is inclined and rotated as shown in FIG. 3 (b) because it is provided only at at least a part of the inner peripheral end 202c and not at the upstream end in the rotation direction of the optical disk 2. In addition, only the edge portion of the upstream end portion 30b of the protective member 30 contacts the surface 2a of the optical disc 2. Therefore, it is possible to prevent or reduce damage to the optical disc 2 due to contact or collision with the locking projection. Further, since the locking projection 203 is not provided on the upstream side 202d in the rotation direction of the optical disc 2 in the protective member mounting area 202, the structure of the mold is simplified when the movable base 201 is formed by resin molding. This makes it easy to manage the tolerance of the inclination angle θ of the protective member mounting area 202.

  4A to 4D show variations of the arrangement of the locking projections 203, respectively. In FIG. 4A, the locking projection 203 is located in the periphery of the protective member mounting area 202 in the downstream end 202 a in the rotation direction (T direction) of the optical disc 2 and in the radial direction (R direction) of the optical disc 2. An example is shown in which a U-shape is formed along the three sides of the outer peripheral end 202b and the inner peripheral end 202c. In FIG. 4B, the locking projection 203 is formed along substantially the entire downstream end 202a, and partially formed along the outer peripheral end 202b and the inner peripheral end 202c. An example is shown. FIG. 4 (c) shows that the locking projection 203 is formed in a substantially L shape along the downstream end 202a and the inner end 202b of the protective member mounting area 202 on the outer peripheral side in the radial direction of the optical disc 2. As for the protection member mounting region 202 on the inner peripheral side in the radial direction of the optical disc 2, an example in which the locking projection 203 is formed in a substantially L shape along the downstream end 202a and the outer end 202b is shown. . FIG. 4D is a combination of the examples shown in FIG. 4B and FIG. 4C. For the protective member mounting region 202 on the outer peripheral side, the downstream end 202a and the inner peripheral end. The locking projection 203 is formed in a substantially L shape along 202b and partially formed along the outer peripheral end 202b. The protective member mounting area 202 on the inner peripheral side in the radial direction of the optical disc 2 is as follows. An example is shown in which the locking projections 203 are formed in a substantially L shape along the downstream end 202a and the outer peripheral end 202b and partially formed along the inner peripheral end 202a.

  By forming the locking projection 203 in this way, the locking projection 203 functions as a positioning guide, and any side of the protective member 30 formed in a sheet shape having a rectangular shape in plan view is connected to the locking projection 203. Positioning and mounting work of the protection member 30 can be performed while being in contact with each other. As a result, the protection member 30 can be easily and accurately attached to the protection member attachment region 202 of the movable base 201.

  4A, 4C, and 4D, among the four corners of the protective member 30 in plan view, the objective lens 17 is located on the downstream side in the rotation direction (T direction) of the optical disc 2. The adhesive used to fix the objective lenses 17 and 27 is temporarily protruded by including a portion in which the locking projection 203 is formed in a substantially L shape so as to guide the corners facing each other. However, the possibility that the adhesive adheres to the protective member 30 is reduced. As a result, it is possible to reduce the possibility that the surface of the optical disc 2 is damaged by the adhesive that has adhered to the protective member 30 and solidified.

  Even if the surface (upper surface) of the protection member 30 in the optical axis direction of the objective lenses 17 and 27 rotates while the optical disk 2 is tilted, the surfaces of the objective lenses 17 and 27 and the lens barrel are the surfaces of the optical disk 2. Needless to say, it is set not to contact 2a. Further, the present invention is not limited to the description of the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the shape of the protection member 30 is not necessarily rectangular in plan view, and may be circular or other shapes.

1 is a cross-sectional view showing an optical system in an optical pickup of an optical disc apparatus according to an embodiment of the present invention. The perspective view which shows the objective-lens protection structure of the optical pick-up of the optical disk device in the said embodiment. (A) is sectional drawing which shows the state which attached the protection member in the objective lens protection structure in the said embodiment, especially the protection member attachment area | region of a movable base, (b) rotates in the state in which the optical disk inclined, and the protection member Sectional drawing which shows the state which contacted. (A)-(d) is a top view which shows the variation of arrangement | positioning of a latching protrusion, respectively. Sectional drawing which shows the variation of arrangement | positioning of the conventional each latching protrusion 203. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up 2 Optical disk 2a The surface of an optical disk 201 Movable base 202 Protective member mounting area 202a The downstream end part of a protective member mounting area 202b The outer peripheral side end part 202c of a protective member mounting area 202d The inner peripheral side end part 202d of a protective member mounting area Upstream end of member mounting area 203 Locking projection 30 Protection member 30a Downstream end of protection member 30b Upstream end of protection member

Claims (4)

Two objective lenses arranged in the tangential direction with respect to the optical disc, each having a different numerical aperture;
Two protective members arranged in a radial direction of the optical disc and arranged substantially symmetrically with respect to a line connecting the optical axes of the two objective lenses;
An optical disc apparatus including an optical pickup including a movable base that holds the two objective lenses and the two protective members,
In a state where the surface of the optical disc and the optical axis of the objective lens are orthogonal, the protective member mounting area of the movable base is an inclined surface so that the downstream side is higher and the upstream side is lower than the rotation direction of the optical disc. Formed,
When the protective member is mounted only on at least a part of the downstream end in the rotation direction of the optical disc, the outer peripheral end in the radial direction of the optical disc, and the inner peripheral end in the protective member mounting region of the movable base. A locking projection that serves as a guide is formed.
The protective member has a sheet shape whose thickness is smaller than that of each part having the smallest size on the bottom surface, and the thickness protrudes from the surface of the protective member mounting region of the movable base of the locking protrusion. An optical disk apparatus having an objective lens protection structure for an optical pickup, wherein the optical lens apparatus is formed of a material having a hardness larger than that of the movable base and smaller in hardness than the material of the movable base.   In a state where the surface of the optical disk and the optical axis of the objective lens are orthogonal to each other, an inclination angle of the protection member mounting region of the movable base with respect to the rotation direction of the optical disk is 3 degrees or more and 10 degrees or less. The optical disc apparatus according to claim 1.   The optical disk apparatus according to claim 1, wherein the protection member has a rectangular shape in plan view.   The locking projection is a portion formed in a substantially L shape so as to guide a corner facing the objective lens located downstream in the rotation direction of the optical disc among the four corners in plan view of the protection member. The optical disk according to claim 3, comprising:

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