JP2012064278A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup that includes a collision prevention member that prevents collision between an objective lens and an optical recording medium and is easily downsized and thinned.SOLUTION: An optical pickup includes an objective lens (not shown) that collects light emitted from a light source on an information recording surface of an optical recording medium, a lens holder 31 that holds the objective lens, and a collision prevention member 40 that is fixedly disposed on the lens holder 31 so as to protrude toward the objective lens and prevents collision between the optical recording medium and the objective lens. The lens holder 31 is provided with through holes 34a, 34b that extend in a direction substantially parallel to a protruding direction of the collision prevention member 40 toward the objective lens and in which the collision prevention member 40 is inserted and held, and is not provided with an abutment surface that performs positioning in the protruding direction of the collision prevention member 40.

Description

  The present invention relates to an optical pickup used when reading information recorded on an optical recording medium and writing information on the optical recording medium.

  Conventionally, light is read when information recorded on an optical disc (an example of an optical recording medium) such as a Blu-ray disc (BD), a digital versatile disc (DVD), or a compact disc (CD) is read or written on the optical disc. A pickup is being used. The optical pickup includes a light source, an objective lens that condenses the light emitted from the light source on the information recording surface of the optical disc, and a light receiving element that receives the return light reflected by the information recording surface.

  When reading information with an optical pickup, it is necessary to control (focusing control) so that the position of the light spot condensed by the objective lens is always on the information recording surface of the optical disc. Needs to be controlled (tracking control) so as to always follow the track of the optical disk. For this reason, in an optical pickup, an objective lens is usually mounted on a lens holder, and can be moved in a focus direction or a track direction by an actuator that moves the lens holder. Note that the focus direction is a direction in contact with and away from the optical disk, and the track direction is a direction parallel to the radial direction of the optical disk.

  By the way, conventionally, in an optical pickup, in order to prevent a collision between an objective lens and an optical disk, a collision prevention member may be provided on the lens holder (see, for example, Patent Documents 1 to 4). With this collision prevention member, it is possible to prevent a situation in which information recorded on the optical disk becomes unusable due to a collision between the objective lens and the optical disk, or the objective lens is damaged and the optical pickup cannot be used. The collision prevention member provided in the lens holder may be a molded product as shown in Patent Documents 1 to 3, for example, or a sheet product (sheet member) as shown in Patent Document 4, for example. Sometimes.

  Here, a configuration of a conventional optical pickup including a collision preventing member made of a sheet member as disclosed in Patent Document 4 will be described with reference to FIGS. 10 and 11. FIG. 10 is a schematic perspective view showing a configuration of an objective lens actuator provided in a conventional optical pickup. 11 is a diagram showing a part of a cross section at the position XX in FIG. In FIG. 11, the optical disk D is also shown for easy understanding.

  An objective lens actuator 100 provided in a conventional optical pickup includes a base 101 and a lens holder 102 that holds an objective lens 110. A pair of permanent magnets 103 are erected on the base 101 so as to be symmetrically arranged with the lens holder 102 interposed therebetween. In addition, a through hole (not shown) is formed in the base 101 so that light emitted from a light source (not shown) (light source of the optical pickup) reaches the objective lens 110.

  The lens holder 102 is formed with a lens holding portion 102 a for holding the objective lens 110. In addition, one end of each of the wires 104 is fixed to two opposing side walls of the lens holder 102 (an outer wall that does not face the permanent magnet 103), three on one side and six on each side. The other end of each wire 104 is fixed to a circuit board 105 erected on the base 101, whereby the lens holder 102 is cantilevered and supported by the wire 104.

  The wire 104 whose one end is fixed to the lens holder 102 is fixed to the circuit board 105 while the other end is inserted into the gel material filling portion 106a of the gel holder 106 fixedly arranged on the base 101. Has been. The gel material filled in the gel material filling portion 106 a serves to attenuate the vibration generated in the wire 104 in accordance with the driving of the lens holder 102.

  Further, the lens holder 102 includes a focus coil (not shown) arranged so as to surround the optical axis of the objective lens 110 along the inner side wall of the lens holder 102, and an outer side wall (side wall facing the permanent magnet 103) of the lens holder 102. ), Four track coils 111 arranged in two each are attached. A current is supplied to these coils via a wire 104.

  When a current flows through the focus coil, the objective lens 110 moves in the focus direction F together with the lens holder 102 according to the direction in which the current flows and the magnitude of the current due to the electromagnetic action with the magnetic field generated by the permanent magnet 103. . Similarly, when a current flows through the track coil 111, the objective lens 110 moves in the track direction T together with the lens holder 102 in accordance with the direction and size.

  A collision preventing member 112 made of a sheet member is disposed on the upper surface 102b of the lens holder 102 outside the lens holding portion 102a. The sheet-like collision preventing member 112 provided in a substantially rectangular plane shape is inserted into the fixing portion 113 so that one of the side surfaces parallel to the thickness direction (side surface 112a; see FIG. 11) faces the optical disc D. The side surface (lower surface) 112b facing the (upper surface) 112a is held in contact with the upper surface 102b of the lens holder 102 (see FIG. 11). The upper surface 112a (tip) of the collision preventing member 112 is higher than the tip of the objective lens 110 (see FIG. 11). For this reason, the collision preventing member 112 collides with the optical disc D before the objective lens 110, and the objective lens 110 and the optical disc D do not collide directly.

  When the anti-collision member 112 is formed of a sheet member as in this conventional example, the anti-collision member is formed of a molded product (for example, it is desired to be easily processed into a spherical shape and formed of such a material). Compared to, it is easy to select a material that is difficult to wear (a wear-resistant material). For this reason, when the collision preventing member 112 and the optical disk D come into contact with each other, it is possible to reduce the possibility that the optical disk D is contaminated due to wear of the collision preventing member 112. Further, since the collision preventing member 112 made of a sheet member is disposed so that the side surface 112a parallel to the thickness direction faces the optical disc D, the contact area between the collision preventing member 112 and the optical disc D is relatively small. it can. For this reason, the frictional force at the time of the contact between the collision preventing member 112 and the optical disk D can be reduced, and the possibility that the optical disk D is damaged can be suppressed low.

Japanese Patent Laid-Open No. 5-197982 JP 2004-139694 A JP 2008-293551 A JP 2010-97626 A

  However, the conventional optical pickup disclosed in Patent Document 4 has the following problems. The recent trend of miniaturization and thinning of optical pickups is no exception for BD-compatible optical pickups, and it is sometimes required to use a small-diameter objective lens for BD-compatible optical pickups. When a small-diameter objective lens (a large numerical aperture (for example, 0.85) is required) is used for a BD-compatible optical pickup, the working distance that is the distance between the tip of the objective lens and the optical disk becomes very short (for example, About 0.3 mm).

  The dimensional tolerance of the outer shape due to the processing of the collision preventing member 112 made of a sheet member is as large as ± 0.08 mm, for example. There is also a dimensional tolerance (for example, ± 0.03 mm) in the height l of the lens holder 102 between the lens placement surface 102c and the collision prevention member placement surface 102b (see FIG. 11). That is, although a very short distance is assumed for the working distance, there is a very large dimensional tolerance for attaching the collision prevention member 112, and in the conventional configuration, a design margin for providing the collision prevention member 112 is present. There is no state.

  In view of the above, an object of the present invention is to provide an optical pickup that includes a collision prevention member that prevents collision between an objective lens and an optical recording medium, and that can easily cope with downsizing and thinning.

  To achieve the above object, the present invention provides a light source, an objective lens that focuses light emitted from the light source on an information recording surface of an optical recording medium, a lens holder that holds the objective lens, and the objective lens. And an anti-collision member fixed to the lens holder so as to protrude relative to the optical recording medium and preventing the optical recording medium and the objective lens from colliding with each other. A through hole is provided that extends in a direction substantially parallel to the protruding direction of the member with respect to the objective lens and into which the collision preventing member is inserted and held, and a contact surface that positions the collision preventing member in the protruding direction is provided. It is characterized by not.

  According to this configuration, the dimensional tolerance when attaching the collision prevention member to the lens holder (the projection direction of the collision prevention member, in other words, the dimensional tolerance in the height direction) is not affected by the outer dimension tolerance of the collision prevention member, It can be determined only by the dimensional tolerance (jig accuracy) of the jig used when attaching the prevention member to the lens holder. Since the dimensional tolerance of the jig can be made relatively small, this configuration is suitable for an optical pickup corresponding to miniaturization and thinning.

  In the optical pickup having the above-described configuration, the collision preventing member may be configured such that, of both end portions in the protruding direction, an end portion side that does not face the optical recording medium is bonded and fixed to the lens holder. According to this configuration, the collision preventing member whose position is adjusted by the jig can be easily fixed using, for example, an ultraviolet curable adhesive (UV adhesive) or the like.

  In the optical pickup configured as described above, the collision preventing member is preferably a sheet member. By making the collision preventing member a sheet member, it is easy to select a wear-resistant material as a material constituting the collision preventing member, and when the collision preventing member comes into contact with the optical recording medium, the optical recording medium may be stained. Can be reduced.

  In the optical pickup having the above configuration, it is preferable that the collision preventing member is disposed so that one of the side surfaces parallel to the thickness direction of the sheet member faces the optical recording medium. According to this configuration, for example, the contact area with the optical recording medium can be reduced as compared with the case where the same sheet member is used and the surface perpendicular to the thickness direction faces the optical recording medium. For this reason, damage to the optical recording medium when the collision preventing member collides with the optical recording medium can be reduced.

  In the optical pickup having the above-described configuration, the collision prevention member is disposed on the lens holder so that the thickness direction is substantially parallel to the rotation direction of the optical recording medium with reference to a position where the collision prevention member is disposed. It is preferable. According to this configuration, even when the collision preventing member collides with the optical recording medium, the contact time between the two can be made relatively short, and the possibility of damage to the optical recording medium can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the optical pick-up which is provided with the collision prevention member which prevents the collision with an objective lens and an optical recording medium, and can respond easily to size reduction and thickness reduction can be provided. The present invention is suitable for an optical pickup having a narrow working distance, such as a BD-compatible optical pickup including a small-diameter objective lens.

Schematic plan view showing the configuration of the optical pickup of the present embodiment Schematic plan view showing the optical configuration of the optical pickup of the present embodiment The schematic perspective view which shows the structure of the lens holder with which the optical pick-up of this embodiment is provided. The schematic perspective view which shows the state before a collision prevention member is attached to the lens holder with which the optical pick-up of this embodiment is provided. The schematic perspective view which shows the structure of the jig | tool used when attaching the collision prevention member to the lens holder with which the optical pick-up of this embodiment is provided. The figure for demonstrating the procedure which attaches a collision prevention member to the lens holder with which the optical pick-up of this embodiment is equipped using a jig | tool. The schematic perspective view which shows the state by which the collision prevention member was adhere | attached and fixed to the lens holder with which the optical pick-up of this embodiment is provided. The schematic diagram which shows the relationship between the collision prevention member attached to the lens holder with which the optical pick-up of this embodiment is provided, an objective lens, and an optical disk The figure which shows the modification of the optical pick-up of this embodiment Schematic perspective view showing the configuration of an objective lens actuator provided in a conventional optical pickup The figure which shows a part of cross section in the XX position of FIG.

  Hereinafter, embodiments of an optical pickup to which the present invention is applied will be described with reference to the drawings.

  1A and 1B are schematic plan views showing the configuration of the optical pickup according to the present embodiment. FIG. 1A is a top view of the optical pickup, and FIG. 1B is a side view of the optical pickup. In addition, FIG.1 (b) is the figure seen along the arrow A shown to Fig.1 (a). In FIG. 1B, the optical disk D is also shown for easy understanding.

  As shown in FIG. 1, the optical pickup 1 of the present embodiment includes a pickup base 10 and an objective lens actuator 30 that is fixedly disposed on the pickup base 10. The optical pickup according to the present embodiment can read and write information with respect to the optical disc D of three kinds of standards such as BD, DVD, and CD, and the first objective lens 17 corresponding to BD. And a second objective lens 23 compatible with DVD and CD.

  Bearing portions 10 a and 10 b are provided at the left and right ends of the pickup base 10. The pickup base 10 is slidably supported by the bearing portions 10a and 10b on a guide shaft GS (shown by a broken line in FIG. 1A) provided in an optical disc apparatus which is a device for reproducing and recording the optical disc D. Will be. The guide shaft GS provided in the optical disc apparatus is disposed so as to extend in the radial direction (radial direction) of the optical disc D. For this reason, the optical pickup 1 slidable with respect to the guide shaft GS can read and write information by accessing a desired address of the rotating optical disk D.

  FIG. 2 is a schematic plan view showing the optical configuration of the optical pickup of the present embodiment. The laser beam having the first wavelength emitted from the first laser diode (LD) 11 is divided into main light and two sub-lights by the diffraction element 12. The laser beam emitted from the diffraction element 12 is reflected by the polarization beam splitter 13 and passes through the quarter-wave plate 14 and the collimating lens 15. Thereafter, the light is reflected by the first raising mirror 16 and reaches the first objective lens 17 above the first raising mirror 16. The first raising mirror 16 is a dichroic mirror, and reflects the laser light having the first wavelength emitted from the first LD 11.

  The first objective lens 17 has a function of condensing incident laser light on the information recording surface RS of the optical disc D (see FIG. 1B). The laser beam condensed on the information recording surface RS by the first objective lens 17 is reflected by the information recording surface RS. This reflected light (returned light) passes through the first objective lens 17 and is then reflected by the first rising mirror 16, and passes through the collimating lens 15, the quarter wavelength plate 14, the polarization beam splitter 13, and the beam splitter 18. The light is sequentially transmitted, and astigmatism is given by the sensor lens 19 to be condensed on the photodetector (light receiving element) 20. The photodetector 20 functions as a photoelectric conversion unit that converts the received optical signal into an electrical signal.

  Note that the first LD 11 is a BD-compatible laser light source in the present embodiment, and emits laser light having a wavelength of 405 nm. The collimating lens 15 can be moved in the optical axis direction (in the direction of arrow M in FIG. 2) by a known lens driving device for the purpose of correcting spherical aberration.

  The second laser diode (LD) 21 can switch and emit the laser light having the second wavelength and the laser light having the third wavelength. The laser light emitted from the second LD 21 is reflected by the beam splitter 18, passes through the polarization beam splitter 13, and then passes through the quarter wavelength plate 14 and the collimating lens 15. Further, the first raising mirror 16 configured as a dichroic mirror also passes therethrough. Then, the light is reflected by the second raising mirror 22 and reaches the second objective lens 23 above the second raising mirror 22.

  The second objective lens 23 has a function of condensing incident laser light on the information recording surface RS (see FIG. 1B) of the optical disc D. The reflected light (returned light) reflected after being focused on the information recording surface RS by the second objective lens 23 passes through the second objective lens 23, is reflected by the second rising mirror 22, and The first rising mirror 16, the collimating lens 15, the ¼ wavelength plate 14, the polarizing beam splitter 13, the beam splitter 18, and the sensor lens 19 are sequentially transmitted and condensed on the photodetector 20.

  In the present embodiment, the second LD 21 is a laser light source compatible with DVD and CD, and has a wavelength of 650 nm band laser light (for DVD; second wavelength laser light) and a wavelength of 780 nm band laser light (for CD). The laser beam having the third wavelength) can be switched and emitted. That is, the second LD 21 includes two types of light sources. Such a laser light source may be, for example, a monolithic type or a hybrid type two-wavelength laser.

  The optical components 11 to 23 described above are all mounted on the pickup base 10, but the first objective lens 17 and the second objective lens 23 are the objective lens actuator 30 disposed on the pickup base 10. In this state, it is mounted on the pickup base 10.

  Similar to the objective lens actuator 100 shown in FIG. 10, the objective lens actuator 30 includes a lens holder that holds the objective lenses 17 and 23, and this lens holder is cantilevered by a wire. Similarly to the objective lens actuator 100 shown in FIG. 10, the objective lenses 17 and 23 are moved together with the lens holder in the focus direction and the track direction by utilizing the electromagnetic action of the magnetic field generated by the magnet and the current flowing through the coil. It can be moved to.

  FIG. 3 is a schematic perspective view showing the configuration of the lens holder included in the optical pickup according to the present embodiment, and FIG. 3A is a view of the state where the objective lens is mounted as seen obliquely from above, and FIG. These are the figures which looked at the state where the objective lens is not mounted from diagonally downward. In the lens holder 31 of the optical pickup 1 (objective lens actuator 30), the two objective lenses 17 and 23 can be held side by side (in this embodiment, side by side in the tangential direction (see FIG. 1)). Two lens holding portions 31a and 31b are provided.

  The first objective lens 17 is provided in the first lens holding portion 31a, the second objective lens 23 is provided in the second lens holding portion 31b, and the lens mounting surface provided in the lens holding portions 31a and 31b from above (see FIG. 11 is the same configuration as the lens mounting surface 102c shown in FIG. The objective lenses 17 and 23 placed on the lens placement surface are fixed with an adhesive or the like.

  The lens holder 31 has two through holes 34a and 34b that pass through the lens holder 31 in the vertical direction between the first lens holding portion 31a and the second lens holding portion 31b in a substantially rectangular shape in plan view. Is provided. The arrangement direction of the two through holes 34 a and 34 b is a direction substantially orthogonal to the arrangement direction of the two objective lenses 17 and 23. In these two through holes 34a and 34b, a collision preventing member to be described later for preventing collision between the objective lenses 17 and 23 and the optical disk D is inserted. The size of each of the through holes 34a, 34b is larger than the outer shape of the collision preventing member so that the collision preventing member is not caught by the inner surface when the collision preventing member is inserted as described later. Slightly larger.

  In addition, a focus coil 32, a track coil 33, and the like used for obtaining the above-described electromagnetic force action are attached to the lens holder 31.

  FIG. 4 is a schematic perspective view showing a state before the collision preventing member is attached to the lens holder included in the optical pickup of the present embodiment. As shown in FIG. 4, the collision preventing members 40 (two) for preventing collision between the objective lenses 17 and 23 and the optical disc D are sheet members having a substantially rectangular planar shape. The collision preventing member 40 is preferably made of a material that generates as little scratches and dirt as possible when it collides with the optical disc D.

  Specifically, it is preferable that the material is softer than the surface layer of the optical disk D formed of polycarbonate or the like (layer that protects the information recording surface RS). Further, a material having wear resistance so as not to be scraped at the time of collision with the optical disc D is preferable. An example of a material that satisfies these conditions is ultra high molecular weight polyethylene (UHMW-PE), and the sheet-like collision prevention member 40 of this embodiment is formed of ultra high molecular weight polyethylene.

  In FIG. 4, the lens holder 31 is assumed to be viewed obliquely from the bottom (the same as in FIG. 3B). That is, in the present embodiment, the collision prevention member 40 is configured to be inserted and attached to the through holes 34 a and 34 b from the back (lower) side of the lens holder 31. Each of the two anti-collision members 40 has its posture (posture in FIG. 4) determined so that one of the side surfaces parallel to the thickness direction faces the optical disc D, and is inserted into the through holes 34a and 34b (see FIG. Inserted in the direction of the dashed arrow 4).

  When attaching the collision preventing member 40 to the lens holder 31, a jig as shown in FIG. 5 is used. FIG. 5 is a schematic perspective view showing a configuration of a jig used when attaching the collision preventing member to the lens holder provided in the optical pickup of the present embodiment.

  As shown in FIG. 5, a support base 52 that supports the lens holder 31 is placed on the base 51 of the jig 50 in a fixed state. On the upper surface 52a of the support base 52, a first convex portion 53 having a substantially cylindrical shape, and a pair of second convex portions 54a having a substantially quadrangular prism shape disposed at symmetrical positions so as to sandwich the first convex portion 53, 54b. In addition, the 1st convex part 53 and a pair of 2nd convex parts 54a and 54b are not located in a straight line exactly, and in FIG. 5, the 1st convex part 53 is a pair of 2nd convex part. It is in front of 54a and 54b. Moreover, the protrusion amount from the upper surface 52a of the support stand 52 of the 1st convex part 53 and a pair of 2nd convex part 54a, 54b is the same.

  Above the support base 52, a pair of holder pressing portions 55a and 55b used for pressing the end side of the lens holder 31 and a sheet-like collision prevention inserted into the through portions 34a and 34b of the lens holder 31. A pair of anti-collision member pressing portions 56a and 56b used for pressing the member 40 is provided. The pair of holder pressing portions 55a and 55b and the pair of collision prevention member pressing portions 56a and 56b are provided to be movable in the vertical direction with respect to the support base 52.

  FIG. 6 is a diagram for explaining a procedure for attaching a collision preventing member to the lens holder provided in the optical pickup according to the present embodiment using a jig, and FIG. 6A shows the jig and the lens holder in the middle of attachment. FIG. 6B is a side view of the state of FIG. 6A. FIG. The procedure described here is an example, and the procedure may be changed as appropriate without departing from the object of the present invention.

  As shown in FIG. 6, when attaching the collision preventing member 40 to the lens holder 31, the lens holder 31 is placed on the support base 52 with the back facing. At this time, each of the two collision prevention members 40 is inserted into the through holes 41 a and 41 b from the back side of the lens holder 31. Then, the lens mounting surface LS (indicated by the alternate long and short dash line in FIG. 6B) of the second lens holding portion 31 b is mounted so as to contact the upper surface of the first convex portion 53 of the support base 52.

  In the present embodiment, since the end side of the lens holder 31 (the end side in the left-right direction in FIG. 6B) is the same surface as the lens placement surface LS, a pair of the same surface is also provided. It is configured to be supported by the second convex portions 54a and 54b. That is, in the present embodiment, the lens holder 31 is supported at three points by the first convex portion 53 and the pair of second convex portions 54a and 54b. Note that the second protrusions 54a and 54b may not be provided depending on circumstances. Further, the lens holder 31 is pressed and fixed from above by the holder pressing portions 55a and 55b so that the lens holder 31 does not move in the state where the three points are supported.

  Next, the sheet-like collision prevention member 40 is moved up (with the support base upper surface 52a) so that one of the side surfaces 40a parallel to the thickness direction is in contact with the upper surface 52a of the support base 52. It is pressed from the side surface 40b (refer to FIG. 4) that faces the side surface that abuts on the side surface. FIG. 6 shows the state at this stage.

  By pressing the collision preventing member 40 with the collision preventing member pressing portions 56a and 56b, the side surface 40a parallel to the thickness direction of the collision preventing member 40 supports the first convex portion 53 (second convex portions 54a and 54b). The lens holder 31 protrudes (projects downward in FIG. 6) by an amount determined according to the amount of protrusion from the table upper surface 52a.

  The amount of protrusion of the first convex portion 53 from the support base upper surface 52a is such that the collision preventing member 40 exhibits a desired collision preventing function (projects by a predetermined amount with respect to the objective lenses 17 and 23 attached to the lens holder 31 later). ) Is determined in advance. In the present embodiment, the height from the lens placement surface LS to the side surface 40a of the collision prevention member 40 facing the optical disc D when the collision prevention member 40 is disposed at a position where the desired collision prevention function can be obtained. However, the amount h of protrusion of the first convex portion 53 from the upper surface 52a of the support base is shown (see FIG. 6B).

  When the anti-collision member 40 is pressed by the anti-collision member pressing portions 56a and 56b, the anti-collision member 40 applies an ultraviolet curable adhesive (UV adhesive) 57 from the back side of the lens holder 31 as shown in FIG. Injection is performed at an appropriate position so as to be fixed to the lens holder 31. Then, after the UV adhesive is cured by irradiating ultraviolet rays, the holding by the jig is released. Thereby, the attachment to the lens holder 31 of the collision prevention member 40 is completed. FIG. 7 is a schematic perspective view showing a state in which the collision preventing member is bonded and fixed to the lens holder included in the optical pickup of the present embodiment.

  FIG. 8 is a schematic diagram showing the relationship between the collision prevention member attached to the lens holder included in the optical pickup of the present embodiment, the objective lens, and the optical disc. As shown in FIG. 8, the collision preventing member 40 disposed on the lens holder 31 is higher (projects) by a predetermined height t than the distal ends of the objective lenses 17 and 23. For this reason, the collision between the objective lenses 17 and 23 and the optical disk D can be prevented by the presence of the collision preventing member 40.

  On the other hand, the collision preventing member 40 may collide with the optical disc D. However, since the collision preventing member 40 is a sheet member, it is easy to select a wear-resistant material and the optical disc D can be prevented from being soiled by contact. In addition, since the side surface 40a parallel to the thickness direction d of the sheet-like collision preventing member 40 is configured to face the optical disc D, for example, the surface perpendicular to the thickness direction is the optical disc D using the same sheet member. The contact area with the optical disk D can be made smaller than in the case of the opposing configuration. For this reason, damage to the optical disk D can be reduced.

  Furthermore, when the position where the collision preventing member 40 is disposed is used as a reference, the thickness direction d of the collision preventing member 40 and the rotation direction of the optical disk D are substantially parallel to each other. For this reason, even if the collision preventing member 40 and the optical disk D collide, the contact time between them can be made relatively short. Also from this point, even if the collision preventing member 40 and the optical disc D come into contact with each other, the possibility that the optical disc D is damaged is reduced.

  As can be seen from the above description, the lens holder 31 in the optical pickup 1 of the present embodiment is not provided with a contact surface for positioning the collision preventing member 40 in the protruding direction (for example, the vertical direction in FIG. 8). It has become. That is, the collision preventing member 40 is positioned only in the protruding direction (vertical direction, height direction) with the jig 50.

  In the case of the configuration of the present embodiment, the dimensional tolerance (the dimensional tolerance in the vertical direction and the height direction) when attaching the collision preventing member 40 to the lens holder 31 is determined only by the jig accuracy, and is very small ( For example, ± 0.03 mm). That is, the outer dimensional tolerance (for example, ± 0.08 mm) of the sheet-like collision preventing member 40, which has been a problem in the case of the conventional configuration, is considered as a dimensional tolerance when the collision preventing member 40 is attached to the lens holder 31. There is no need. For this reason, even with an optical pickup having a very small working distance, it is possible to realize a configuration in which the sheet-like collision prevention member 40 is arranged so that the side surface parallel to the thickness direction d faces the optical disc D. is there.

  The embodiment described above is an example of the present invention, and the optical pickup of the present invention is not limited to the configuration described above.

  For example, in the above-described embodiment, the two collision preventing members 40 are provided. However, the present invention is not limited to this configuration. The number of the collision preventing members 40 can be changed as appropriate, and may be one or three or more. Further, the position when the collision preventing member 40 is arranged on the lens holder 31 may be changed as appropriate. In short, the collision preventing member 40 may be arranged so as to reduce the possibility that the optical disc D and the objective lenses 17 and 23 collide, and is not limited to the configuration of the embodiment described above. The shape of the lens holder 31 is not limited to the configuration of the present embodiment.

  Further, in the embodiment described above, the shape of the sheet-like collision preventing member 40 is a substantially rectangular planar shape, but is not limited to this shape, and may be appropriately changed to other shapes such as a substantially planar planar shape. It doesn't matter. Further, the collision preventing member may not be a sheet member but may be a molded product (for example, a cylindrical shape or the like) in some cases. Even in this case, the lens holder and the anti-collision member are not provided with a contact surface for positioning the anti-collision member in the protruding direction (vertical direction). Pickup can be provided.

  In the embodiment described above, the thickness direction d of the collision preventing member 40 and the rotation direction of the optical disc D are substantially parallel. This configuration is preferable, but the two may not necessarily be in a substantially parallel relationship.

  Further, in the embodiment described above, the optical pickup 1 is configured to include the two objective lenses 17 and 23. However, the present invention is not limited to this, and the present invention can be applied even when the optical pickup includes one objective lens or three or more objective lenses.

  In the embodiment described above, the objective lens actuator 30 is configured such that the lens holder 31 is cantilevered by a wire (wire support type objective lens actuator). However, the configuration of the objective lens actuator is not limited to this configuration. For example, a so-called shaft sliding type objective lens actuator 60 as shown in FIG. 9 (cross-sectional view) may be used. Also in this case, the same effect can be obtained by providing the collision preventing member with the same configuration as in the present embodiment.

  The objective lens actuator 60 shown in FIG. 9 includes a base 61, a sliding shaft 62, a collision prevention member 66, a lens holder 63 that holds the objective lens 65, a focus coil 64, and a track coil (not shown). Attached to the side surface of the lens holder 63). In the objective lens actuator 60, the lens holder 63 moves up and down with respect to the sliding shaft 62 by an electromagnetic force action between a magnetic field of a permanent magnet (not shown) and a current flowing through a coil (focus coil and track coil). Slide in the direction or direction of rotation.

  In addition, in the above-described embodiments, the optical pickup corresponds to BD, DVD, and CD, but of course, light corresponding to other optical discs (including one type and plural types). The present invention can also be applied to a pickup. If the optical pickup supports only one type of optical disk, the number of light sources and objective lenses may be one.

  The present invention is suitable for an optical pickup corresponding to a reduction in size and thickness.

DESCRIPTION OF SYMBOLS 1 Optical pick-up 11 1st light source 17 1st objective lens 18 2nd light source 19 2nd objective lens 31 Lens holder 34a, 34b Through-hole 40 Collision prevention member D Optical disk (optical recording medium)
RS information recording surface

Claims (5)

A light source;
An objective lens for condensing the light emitted from the light source on the information recording surface of the optical recording medium;
A lens holder for holding the objective lens;
A collision preventing member which is fixedly disposed on the lens holder so as to protrude with respect to the objective lens and prevents a collision between the optical recording medium and the objective lens;
In an optical pickup comprising:
The lens holder is provided with a through-hole extending in a direction substantially parallel to a protruding direction of the collision preventing member with respect to the objective lens and into which the collision preventing member is inserted, and the protruding direction of the collision preventing member An optical pickup characterized in that a contact surface for positioning is not provided.   2. The optical pickup according to claim 1, wherein the collision preventing member is bonded and fixed to the lens holder at an end of the projecting direction that is not opposed to the optical recording medium.   The optical pickup according to claim 2, wherein the collision preventing member is a sheet member.   The optical pickup according to claim 3, wherein the collision preventing member is disposed such that one of the side surfaces parallel to the thickness direction of the sheet member faces the optical recording medium.   The collision preventing member is disposed in the lens holder so that the thickness direction is substantially parallel to the rotation direction of the optical recording medium with reference to a position where the collision preventing member is disposed. The optical pickup according to claim 4.

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