JP2010282701A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup, of which the prevention of collision of an objective lens with an optical disk is attainable at a low cost, and scratch and dirt hardly occur on the optical disk even though a collision preventive member collides with the optical disk. <P>SOLUTION: The optical pickup 1 includes: a light source 11; the objective lens 17 for condensing light from the light source 11 to an information recording surface 70a of the optical disk 70; a lens holder 32 for holding the objective lens 17; and the collision preventive member 36 prepared on the lens holder 32 to prevent the collision between the optical disk 70 and the objective lens 17. The collision preventive member 36 is composed of a triangular pillar shaped sheet member and disposed in the lens holder 32 so that one among three side surfaces 36c, 36d, 36e in the thickness direction of the sheet member formes a bottom face. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical pickup, and more particularly to a configuration of an optical pickup including an objective lens that condenses light from a light source on an information recording surface of an optical disc and a collision prevention member that prevents the optical disc from colliding.

  Conventionally, optical discs such as compact discs (hereinafter referred to as CDs), digital versatile discs (hereinafter referred to as DVDs), and Blu-ray discs (hereinafter referred to as BDs) are widely used. An optical pickup is used to read information recorded on such an optical disc and write information on the optical disc. 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 unit that receives the return light reflected by the information recording surface.

  When reading or writing information using an optical pickup, the focal position of the objective lens is controlled so that the light emitted from the light source is always in focus with the information recording surface of the optical disc regardless of the surface shake of the optical disc. There is a need. For this reason, in the optical pickup, the objective lens is held by a lens holder, and the lens holder is moved in the direction of contact with and away from the optical disk by an actuator, and the positional relationship between the objective lens and the optical disk is controlled to be always constant. ing. Hereinafter, such control is expressed as focus servo control.

  By the way, in an optical disc capable of recording a large amount of information such as the above-mentioned BD, information is recorded with high density. Therefore, when information is read using an optical pickup, it is necessary to reduce the spot size of the light spot formed on the optical disk. As a method for reducing the spot size of the light spot, conventionally, the wavelength of light emitted from the light source is shortened and the numerical aperture of the objective lens is increased.

  When the numerical aperture of the objective lens is increased, the distance (working distance; WD) between the tip of the objective lens and the optical disc tends to be narrowed when information is read by the optical pickup, and in an optical pickup corresponding to BD. WD is narrow. When the WD becomes narrow in this way, for example, when an optical disk with large surface wobbling is used, or when focus servo control cannot be performed due to scratches on the optical disk or external vibrations, etc. The possibility that the objective lens and the optical disk collide is very high.

  Note that the situation where the WD becomes narrow is not limited to the optical pickup corresponding to the BD, and may occur also in the optical pickup corresponding to an optical disc such as a CD or a DVD. That is, in a notebook personal computer or the like, since a reduction in thickness is required, the objective lens provided in the optical pickup is a small-diameter lens. Even when such a small-diameter objective lens is used, the WD becomes narrow, and the possibility that the objective lens collides with the optical disc becomes very high.

  For this reason, in a conventional optical pickup, a collision preventing member for preventing a collision between the objective lens and the optical disk may be provided in a lens holder that holds the objective lens (for example, Patent Document 1, 2). This prevents the information recorded on the optical disc from being used due to the collision between the objective lens and the optical disc, or the objective lens from being damaged and making the optical pickup unusable.

JP 2008-293551 A JP 2007-305179 A

  By the way, the collision preventing member is required to have a small frictional force when it comes into contact with the optical disc so as not to damage the optical disc at the time of collision. For this reason, for example, as disclosed in Patent Document 1, it is effective to form the collision preventing member in a mountain shape and reduce the contact area at the time of the collision. However, when the anti-collision member is a molded product as in Patent Documents 1 and 2, there are the following problems.

  When the anti-collision member is made of a molded product, it is difficult to form the anti-collision member using a wear-resistant material. This is because wear-resistant materials are difficult to process. For this reason, when the anti-collision member is a molded product, the wear resistance of the anti-collision member tends to be insufficient, and when the anti-collision member collides with the optical disc, the optical disc tends to become dirty. . If the optical disk becomes dirty due to the wear of the collision preventing member, it is difficult to read information by the optical pickup, which adversely affects the reproduction characteristics.

  In view of the above points, the object of the present invention is to realize a collision prevention between the objective lens and the optical disk at a low cost, and to prevent the optical disk from being scratched or soiled even when the collision preventing member collides with the optical disk. Is to provide a pickup.

  To achieve the above object, the present invention is provided in a light source, an objective lens that condenses light from the light source on an information recording surface of an optical disc, a lens holder that holds the objective lens, and the lens holder. In the optical pickup comprising a collision preventing member for preventing a collision between the optical disk and the objective lens, the collision preventing member is composed of a triangular prism-shaped sheet member, and has three side surfaces in the thickness direction of the sheet member. One of them is arranged on the lens holder so as to be a bottom surface.

  According to this configuration, since the collision preventing member is made of a sheet member, the shape of the collision preventing member is simple, and the processing cost can be reduced. Moreover, since the collision preventing member is composed of a sheet member, the collision preventing member can be easily formed using a wear-resistant material. For this reason, even when the collision preventing member and the optical disc collide, dirt is hardly attached to the optical disc. Further, since the collision preventing member is a triangular prism-shaped sheet member and is arranged on the lens holder so that one of the three side surfaces in the thickness direction of the sheet member becomes the bottom surface, the collision preventing member And the contact area between the optical disk and the optical disk can be reduced. For this reason, even when the collision preventing member collides with the optical disc, the optical disc is hardly damaged.

  In the optical pickup configured as described above, it is preferable that a cross-sectional shape of the collision preventing member is a right triangle. According to this, the anti-collision member made of a triangular prism-shaped sheet member can be manufactured with almost no unnecessary portion, and the cost of the optical pickup can be reduced.

  In the optical pickup having the above-described configuration, it is preferable that the anti-collision member has a vertex arranged near the outer periphery of the lens holder. This is because the possibility that the objective lens and the optical disk collide can be further reduced if the apex, which is the highest portion of the collision preventing member, is arranged near the outer periphery of the lens holder.

  The optical pickup having the above-described configuration preferably includes at least one pair of the pair of anti-collision members arranged symmetrically with the objective lens interposed therebetween. By arranging the collision preventing member in this way, the possibility that the objective lens and the optical disk collide can be reduced.

  In the optical pickup having the above-described configuration, it is preferable that the lens holder has an insertion hole for inserting the collision prevention member and a fixing portion for fixing the collision prevention member on the lens holder. By providing such a fixing portion, the collision preventing member made of a sheet member can be accurately placed on the lens holder.

  According to the optical pickup of the present invention, collision prevention between the objective lens and the optical disk can be realized at low cost. Further, according to the optical pickup of the present invention, even if the collision preventing member and the optical disk collide, the optical disk is hardly damaged or soiled. Therefore, according to the optical pickup of the present invention, the quality of reading information recorded on the optical disc and the quality of recording information on the optical disc can be made stable.

Schematic plan view showing the configuration of the optical pickup of the present embodiment Schematic which shows the structure of the optical system with which the optical pick-up of this embodiment is provided. The figure for demonstrating the structure of the objective-lens actuator of this embodiment. The schematic perspective view which shows the state before the collision prevention member with which the optical pick-up of this embodiment is provided is fixedly arrange | positioned on a lens holder. The schematic perspective view which shows the state by which the collision prevention member with which the optical pick-up of this embodiment is provided was fixedly arrange | positioned on the lens holder. The figure for demonstrating the relationship between the objective lens and collision prevention member in the optical pick-up of this embodiment. The figure which shows the state when a lens holder inclines and a collision prevention member collides with an optical disk The comparison figure shown in order to demonstrate the effect of the collision prevention member with which the optical pickup of this embodiment is provided It is a figure for demonstrating the modification regarding the structure of the optical pick-up of this embodiment, and is a figure at the time of seeing the collision prevention member arrange | positioned on a lens holder from the top The figure for demonstrating the modification of the optical pick-up of this embodiment.

  Hereinafter, embodiments of an optical pickup according to the present invention will be described in detail with reference to the drawings.

  First, a schematic configuration of the optical pickup according to the present embodiment will be described with reference to FIGS. FIG. 1 is a schematic plan view showing the configuration of the optical pickup of the present embodiment. FIG. 2 is a schematic diagram showing a configuration of an optical system provided in the optical pickup of the present embodiment. 3A and 3B are diagrams for explaining the configuration of the objective lens actuator included in the optical pickup according to the present embodiment. FIG. 3A is a schematic perspective view showing the overall configuration of the objective lens actuator, and FIG. It is a schematic perspective view which shows the structure of the coil with which a lens actuator is provided.

  As shown in FIG. 1, the optical pickup 1 of this embodiment includes a slide base 2. The slide base 2 is provided with two types of bearing portions 2a and 2b. The slide base 2 is slidably supported by two guide shafts 71 (members prepared separately from the optical pickup 1) extending in the radial direction of the optical disk (not shown) using the bearing portions 2a and 2b. As a result, the optical pickup 1 can move in the radial direction. The slide base 2 is moved by a known moving mechanism (not shown). As an example of a known moving mechanism, there is a configuration using a rack attached to the slide base 2 and a pinion rotated by a motor.

  An optical system as shown in FIG. 2 is mounted on the slide base 2. Specifically, on the slide base 2, a light source 11, a diffraction element 12, a polarization beam splitter 13, a quarter wavelength plate 14, a collimator lens 15, a rising mirror 16, an objective lens 17, An optical system including a cylindrical lens 18 and a photodetector 19 is mounted. The objective lens 17 is mounted on the slide base 2 while being mounted on the objective lens actuator 3.

  The light source 11 is composed of a semiconductor laser, and the optical disk 70 to which the optical pickup 1 of the present embodiment corresponds is a BD. Therefore, a semiconductor laser that emits laser light in the 405 nm band is used. Note that the wavelength of light emitted from the semiconductor laser is appropriately changed depending on the type of optical disk supported by the optical pickup. The diffraction element 12 divides laser light emitted from the light source 11 into main light and two sub-lights. The reason why the light from the light source 11 is divided into three lights is to obtain a signal necessary for servo control.

  The polarization beam splitter 13 functions as an optical isolator in cooperation with the quarter wavelength plate 14. That is, the polarization beam splitter 13 reflects the laser light from the light source 11 and guides it to the optical disc 70 side, but transmits the return light reflected by the optical disc 70 and guides it to the photodetector 19 side.

  The collimating lens 15 is a lens that converts incident laser light into parallel light. However, in the optical pickup 1 of the present embodiment, the collimating lens 15 is movable in the optical axis direction (the direction of the arrow pointing left and right in FIG. 2). For this reason, the laser light emitted from the light source 11 and emitted from the collimator lens 15 is not necessarily parallel light but may be convergent light or divergent light. In this way, the position of the collimating lens 15 can be adjusted by adjusting the convergence state or diverging state of the laser light incident on the objective lens 17 by moving the position of the collimating lens 15 to correct spherical aberration. Because.

  The method for moving the collimating lens 15 in the optical axis direction may be a known configuration. For example, the movable holder holding the collimating lens 15 can be configured to move using a motor and a lead screw (both not shown) along a guide shaft extending in the optical axis direction.

  The rising mirror 16 reflects the laser beam sent from the collimating lens 15. Thereby, the traveling direction of the laser light emitted from the light source 11 is bent, and becomes a light traveling in a direction orthogonal to the information recording surface 70 a of the optical disk 70.

  The objective lens 17 focuses the laser beam sent from the rising mirror 16 on the information recording surface 70 a of the optical disc 70. As described above, the objective lens 17 is mounted on the objective lens actuator 3. Then, the objective lens actuator 3 causes the objective lens 17 to move toward and away from the optical disc 70 (up and down direction in FIG. 2) and in a direction parallel to the radial direction of the optical disc 70 (in FIG. 2, with respect to the paper surface). In a direction perpendicular to the track direction).

  With reference to FIG. 3, the structure of the objective lens actuator 3 provided in the optical pickup 1 will be described. The objective lens actuator 3 includes an act base 31 and a lens holder 32 that holds the objective lens 17. On the act base 31, a pair of permanent magnets 33 are erected so as to be symmetrically arranged with the lens holder 32 interposed therebetween. Further, an optical path hole (not shown) is formed in the act base 31 so that the laser light reflected by the rising mirror 16 can be guided to the objective lens 17.

  The lens holder 32 is integrally formed with a lens holding portion 32a for holding the objective lens 17 and two fixing portions 37 for fixing and disposing a collision preventing member 36, which will be described in detail later. . In addition, one end of each of the wires 34 is fixed to the lens holder 32, three on one side and six on each side. The other end of each wire 34 is fixed to a circuit board 35 erected on the act base 31, so that the lens holder 32 is swingably supported by the wire 34.

  Further, the lens holder 32 includes a focus coil 321 disposed so as to surround the optical axis of the objective lens 17 along the inner side wall of the lens holder 32, and an outer side wall of the lens holder 32 (a side wall facing the permanent magnet 33). The four track coils 322 are attached at two symmetrical positions. A current is supplied to these coils 321 and 322 via a wire 34.

  When a current flows through the focus coil 321, the objective lens 17 moves in the focus direction F together with the lens holder 32 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 33. To do. Similarly, when a current flows through the track coil 322, the objective lens 17 moves in the track direction T together with the lens holder 32 according to the direction and size.

  Returning to FIG. 2, the return light reflected by the information recording surface 70 a passes through the objective lens 17, the rising mirror 16, the collimating lens 15, the quarter-wave plate 14, and the polarization beam splitter 13 in this order, and the cylindrical lens. 18 is sent. The cylindrical lens 18 gives astigmatism to the incident laser light. The astigmatism is given by the cylindrical lens 18 in order to obtain a signal necessary for performing the servo control.

  The laser beam given astigmatism by the cylindrical lens 18 is focused on the light receiving region of the photodetector 19. The photodetector 19 converts the optical signal received in the light receiving area into an electrical signal and outputs it. The electrical signal output from the light detector 19 is processed into, for example, a reproduction signal, a focus error signal, a track error signal, and the like.

  The objective lens actuator 3 is controlled based on the focus error signal and the track error signal, and servo control such as focus servo control and track servo control is performed. As described above, the focus servo control is control performed so that the positional relationship between the objective lens 17 and the optical disc 70 is always constant. The track servo control is control performed so that a light spot formed by collecting light incident on the objective lens 17 always follows a track formed on the optical disc 70.

  The schematic configuration of the optical pickup 1 of the present embodiment is as described above, but the optical pickup 1 of the present embodiment is characterized by a configuration that prevents the objective lens 17 and the optical disc 70 from colliding with each other. This will be described in detail below.

  In the optical pickup 1, a pair of collision preventing members 36 are disposed on the lens holder 32 of the objective lens actuator 3 so that the collision between the objective lens 17 and the optical disk 70 can be prevented (see, for example, FIG. 3A). ). As shown in FIG. 1 and FIG. 3A, the pair of collision preventing members 36 are disposed almost symmetrically with the objective lens 17 in between in the track direction.

  FIG. 4 is a schematic perspective view showing a state before the collision preventing member provided in the optical pickup of the present embodiment is fixedly arranged on the lens holder. FIG. 5 is a schematic perspective view showing a state in which the collision preventing member provided in the optical pickup of the present embodiment is fixedly disposed on the lens holder. As shown in FIG. 4, the collision prevention member 36 provided in the optical pickup 1 includes two triangular surfaces 36a and 36b and three rectangular surfaces 36c, 36d, and 36e (the three rectangular surfaces correspond to the side surfaces in the thickness direction). And a triangular prism-shaped sheet member. The triangles forming the triangular surfaces 36a, 36b are right triangles. For this reason, the cross-sectional shape of the sheet member constituting the collision preventing member 36 is a right triangle. The thickness d of the sheet member constituting the collision preventing member 36 is, for example, 0.5 mm, but it goes without saying that the thickness d can be appropriately changed.

  As a material of the sheet member constituting the collision preventing member 36, it is preferable to select a material that does not cause scratches or dirt on the optical disc 70 when it collides with the optical disc 70. Specifically, the material is preferably softer than the protective layer 70b (see FIG. 2; the layer protecting the information recording surface 70a) of the optical disk 70 formed of polycarbonate or the like. In addition, a material having wear resistance that does not scrape when colliding with the optical disk 70 is preferable. Examples of such a material include ultra high molecular weight polyethylene (UHMW-PE), polyacetal, and tetrafluoroethylene. In the present embodiment, as a particularly preferable embodiment, ultrahigh molecular weight polyethylene (UHMW-PE) is selected as the sheet member constituting the collision preventing member 36.

  The collision preventing member 36 is fixedly disposed on the fixing portion 37 integrally formed with the lens holder 32 as described above. The fixing portion 37 is formed with a substantially rectangular parallelepiped insertion hole 37a so that the collision preventing member 36 made of a sheet member can be inserted and held. Further, on the side surface of the fixing portion 37 (one of the two side surfaces parallel to the track direction), a first anti-collision member 36 inserted and held in the insertion hole 37a is attached from the upper side to the lower side so as to be bonded and fixed. One notch 37b is formed. In the present embodiment, the second notch 37c is formed on the side surface opposite to the side surface where the first notch 37b is formed. This is for facilitating the work when the collision preventing member 36 is fixedly arranged on the fixing portion 37.

  In addition, since it is the structure which provides the two collision prevention members 36 as mentioned above, the two fixing | fixed parts 37 are also provided. And these two fixing | fixed part 37 is also arrange | positioned substantially symmetrically on both sides of the objective lens 17 in the track direction (refer FIG.1 and FIG.3).

  As shown in FIGS. 4 and 5, the collision preventing member 36 made of a triangular prism-shaped sheet member has a rectangular surface 36e, which is one of the three rectangular surfaces 36c, 36d, and 36e included therein, as a bottom surface. In this way, it is inserted into the insertion hole 37 a of the fixing portion 37. The collision preventing member 36 is bonded and fixed to the fixing portion 37 by an adhesive 38 injected into the lower side of the first notch 37b. In the state where the collision preventing member 36 is bonded and fixed to the fixing portion 37, the apex 36 p that is the highest portion of the collision preventing member 36 protrudes from the fixing portion 37.

  For adhesion of the collision preventing member 36 to the fixed portion 37, for example, a UV adhesive or the like that is cured by UV irradiation is used. In addition, when the anti-collision member 36 is fixed to the fixing portion 37, the anti-collision member 36 is cured from the upper side (vertex 36p) side, or from the upper side and side surface (here, the triangular surface 36b) side. It is in a state where it is suppressed with tools. And UV adhesive etc. are inject | poured in the state restrained with this jig | tool, and an adhesive agent is hardened. The reason for fixing with the jig held in this way is to suppress the variation in the height direction of the collision preventing member 36. Further, it is preferable that the collision preventing member 36 is attached to the fixing portion 37 before the wire 34 is attached to the lens holder 32 because workability is good.

  FIG. 6 is a diagram for explaining the relationship between the objective lens and the collision preventing member in the optical pickup according to the present embodiment. The collision preventing member 36 prevents collision between the objective lens 17 and the optical disk 70 (see FIG. 2). For this reason, as shown in FIG. 6, the apex 36 p (pointing to the highest portion) of the collision preventing member 36 is higher than the tip of the objective lens 17 by a predetermined height h. The predetermined height h is appropriately determined by experiment, simulation, or the like.

  By the way, in the optical pickup 1 of the present embodiment, when the collision preventing member 36 made of a triangular prism-shaped sheet member is inserted and held in the fixing portion 37, the vertex 36p of the collision preventing member 36 is set close to the outer periphery of the lens holder 32. ing. The reason for this will be described with reference to FIG.

  FIG. 7 is a diagram illustrating a state where the lens holder is tilted and the collision preventing member collides with the optical disc. In FIG. 7, the solid line indicates the case of the configuration of the present embodiment, and the collision preventing member 36 is fixedly disposed on the fixing portion 37 so that the apex 36 p of the collision preventing member 36 is close to the outer periphery of the lens holder 32. FIG. In FIG. 7, the broken line is shown for comparison with the configuration of the present embodiment, and the collision preventing member 36 is fixed to the fixing portion 37 so that the apex 36 p of the collision preventing member 36 is closer to the center of the lens holder 32. It is a figure in the case of arrangement | positioning. FIG. 7 shows a state in which the lens holder 32 is inclined in the track direction.

  As shown in FIG. 7, when the apex 36 p of the collision preventing member 36 is arranged closer to the outer periphery of the lens holder 32, the collision preventing member 36 collides with the optical disc 70 when the objective lens 17 is tilted less. . For this reason, it is easy to reduce the possibility that the objective lens 17 and the optical disk 70 collide with each other. Therefore, in the optical pickup 1 of the present embodiment, as a more preferable form, the direction of the collision preventing member 36 is determined and inserted into the fixing portion 37 so that the apex 36p of the collision preventing member 36 is closer to the outer periphery.

  The collision prevention member 36 included in the optical pickup 1 of the present embodiment is formed as described above. In addition to being able to prevent the collision between the objective lens 17 and the optical disk 70 with a high probability by forming as described above. There are the following effects.

  That is, in the optical pickup 1 of the present embodiment, the collision preventing member 36 is configured by a sheet member. Since the collision preventing member 36 has a simple shape as described above, the optical pickup 1 according to the present embodiment is difficult to process, so that it is difficult to apply to the conventional collision preventing member. The collision preventing member 36 can be formed by applying the above material. Therefore, in the optical pickup 1 of the present embodiment, even if the collision preventing member 36 and the optical disc 70 collide, the optical disc 70 is hardly contaminated.

  Further, the shape of the collision preventing member 36 made of a sheet member is a triangular prism shape. For this reason, the contact area with the optical disk 70 can be reduced as compared with the case where the collision preventing member is a square columnar sheet member 40 as shown in FIG. Therefore, even when the collision preventing member 36 and the optical disk 70 are in contact with each other, the coefficient of dynamic friction generated between them can be reduced, and the possibility that the optical disk 70 is damaged can be reduced. Further, by forming the sheet member constituting the collision preventing member 36 into a triangular prism shape, the number of sheet members can be doubled compared to the case of a quadrangular prism shape, and the manufacturing cost of the optical pickup 1 can be reduced. It is also possible to suppress it.

  FIG. 8 is a comparative view shown for explaining the effect of the collision preventing member provided in the optical pickup of the present embodiment.

  In the configuration of the present embodiment, the collision preventing member 36 is inserted into the fixing portion 37 and fixed with an adhesive. For this reason, it is easier to manage the height of the collision prevention member 36 than in the case where an adhesive is attached to the bottom surface of the collision prevention member 36 made of a sheet member and is fixed to the lens holder 32, and the workability and cost are excellent. . In addition, although it refuses for the time being, the case where the collision prevention member 36 is affixed with an adhesive material is also included in the scope of the present invention.

  The embodiment described above is an example, and the optical pickup of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the object of the present invention.

  For example, in the embodiment described above, the two anti-collision members 36 are arranged on the lens holder 32. However, the present invention is not limited to this configuration. That is, the number of collision preventing members 36 may be one or three or more. However, as in the present embodiment, the collision preventing members 36 are preferably provided in pairs so as to be symmetrically arranged with the objective lens 17 interposed therebetween, and preferably an even number of 2 or more.

  Further, the position of the collision preventing member 36 on the lens holder 32 may be appropriately changed. FIG. 9 is a view for explaining a modification example of the configuration of the optical pickup according to the present embodiment, and is a view when a collision preventing member arranged on the lens holder is viewed from above. FIG. 9A shows the configuration of the present embodiment.

  FIG. 9B shows a state where the direction of the collision preventing member 36 is rotated by 90 degrees from the state shown in FIG. That is, in FIG. 9B, the triangular surfaces 36a and 36b (see FIG. 4) of the collision preventing member 36 are perpendicular to the track direction. In the example shown in FIG. 9B, the two collision prevention members 36 have their vertices 36 p (the highest portion) symmetrical with respect to the center O of the objective lens 17. 9B, the apex 36p of the collision preventing member 36 is disposed near the outer periphery of the lens holder 32 (in this configuration, the entire collision preventing member 36 is simply disposed closer to the outer periphery of the lens holder 32. It is preferable that it is arranged in a).

  In FIG. 9C, the direction of the collision preventing member 36 is the same as in the case of FIG. 9A, and two diagonal corners of the four corners of the substantially rectangular lens holder 32 are formed. A collision preventing member 36 is disposed in the vicinity. A broken line in FIG. 9C indicates an alternative position of the collision preventing member 36. Of course, the collision preventing member 36 may be provided at all four corners.

  In FIG. 9, the fixing portion for fixing the collision preventing member 36 is omitted. As a matter of course, the shape and position of the fixing portion are changed from the case of the present embodiment in accordance with the change in the arrangement of the collision preventing member 36.

  In the embodiment described above, the cross-sectional shape of the collision preventing member 36 made of a triangular prism-shaped sheet member is a right triangle. However, the cross-sectional shape may be a triangle and may not be a right triangle. However, if the cross-sectional shape of the collision preventing member 36 is a right triangle, the collision preventing member can be manufactured without waste without discharging unnecessary portions. Further, the apex (the highest portion) of the collision preventing member 36 can be easily disposed near the outer periphery of the lens holder 32.

  In the above-described embodiment, the objective lens actuator 3 is configured such that the lens holder 32 is supported by the wire 34 and the lens holder 32 is moved by the swinging of the wire 34 (wire support type objective). Lens actuator). However, the configuration of the objective lens actuator provided in the optical pickup is not limited to this configuration. For example, a so-called shaft sliding type objective lens actuator 100 as shown in FIG. 10 may be used. Also in this case, the same effect can be obtained by providing a collision prevention member having the same configuration as that of the present embodiment.

  The objective lens actuator 100 shown in FIG. 10 includes a base 101, a sliding shaft 102, a lens holder 103 that holds the objective lens 105, and a focus coil 104. In the objective lens actuator 100, a force is generated in a direction parallel to the longitudinal direction of the sliding shaft 102 by an electromagnetic force action between a magnetic field of a permanent magnet (not shown) and a current flowing through the focus coil. It has become. Thereby, focus adjustment is possible.

  In addition, in the embodiment described above, the optical pickup corresponds to one type of optical disk. However, the present invention is naturally applicable to an optical pickup corresponding to a plurality of types of optical disks (including such an optical pickup including a lens holder on which a plurality of objective lenses are mounted). Needless to say, the type of optical disc supported by the optical pickup is not limited to the configuration of the present embodiment.

  According to the optical pickup of the present invention, the collision between the objective lens and the optical disk can be prevented by the collision preventing member. Further, even if the collision preventing member and the optical disc collide, there is a low possibility that the optical disc is damaged or soiled. Moreover, such a collision prevention member can be provided at low cost. Therefore, the present invention is a technique suitable for an optical pickup.

DESCRIPTION OF SYMBOLS 1 Optical pick-up 11 Light source 17 Objective lens 32 Lens holder 36 Collision preventing member 36c, 36d, 36b Rectangular surface (side surface of thickness direction)
36p vertex 37 fixed part 37a insertion hole 70 optical disc 70a information recording surface

Claims (5)

A light source;
An objective lens for condensing the light from the light source on the information recording surface of the optical disc;
A lens holder for holding the objective lens;
In the optical pickup provided with the lens holder, and a collision preventing member that prevents the optical disk and the objective lens from colliding with each other,
The optical pickup is characterized in that the collision preventing member is a triangular prism-shaped sheet member, and is arranged on the lens holder so that one of three side surfaces in the thickness direction of the sheet member is a bottom surface. .   The optical pickup according to claim 1, wherein a cross-sectional shape of the collision preventing member is a right triangle.   The optical pickup according to claim 1, wherein the anti-collision member has a vertex arranged near the outer periphery of the lens holder.   4. The optical pickup according to claim 1, wherein the optical pickup includes at least one pair of the anti-collision members arranged symmetrically with respect to the objective lens. 5.   5. The lens holder according to claim 1, wherein the lens holder has an insertion hole for inserting the collision preventing member, and a fixing portion for fixing the collision preventing member on the lens holder is formed. The optical pickup according to Crab.

Images