JP2011003230A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup which inexpensively achieves structure for assembling a grating to an optical pickup, and in which unbalance load is hard to apply to a holder holding a grating in phase adjustment of the grating.SOLUTION: A grating holder 20 provided in the optical pickup includes: a plate-shaped part 21 having almost circular shape in a plane view in which a through hole 21c is formed and the grating 12 is junction-held; at least three projection parts 22 projected from a plate surface of the plate-shaped part 21; and at least three projection piece parts 23 projected to a reverse side to the projection direction of the projection part 22 from the peripheral edge part of the plate-shaped part 21 and deformed elastically.

Description

  The present invention relates to an optical pickup used for reading information recorded on an optical disk and writing information on an optical disk, and more specifically, a grating (diffraction grating) provided in an optical pickup for the purpose of obtaining a servo signal or the like. ) Is suitable for assembling the optical pickup into the optical pickup.

  Conventionally, a grating is arranged in an optical system of an optical pickup so that a servo signal such as a tracking error signal can be generated. Since this grating requires phase adjustment when it is assembled to the optical pickup, it is attached to the optical pickup housing so that it can be rotated around the optical axis, and after phase adjustment (rotation adjustment) Generally, it is fixed (for example, refer to Patent Documents 1 and 2).

  Recently, an optical disc capable of recording high-capacity information such as a Blu-ray disc (hereinafter referred to as BD) has been put into practical use. However, a BD-compatible optical pickup has a more complicated grating shape than the conventional one. For this reason, it is difficult to form a grating with resin, and a grating is usually formed with glass. And when forming a grating with glass in this way, it is difficult to set it as the structure which rotates grating itself like patent document 1. FIG. For this reason, it is common to adjust the phase of the grating by holding the grating with a holder as in Patent Document 2 and rotating the holder.

Japanese Patent Laid-Open No. 2004-22034 JP 2006-260678 A

  Here, a conventional configuration adopted by the present applicant when the grating is assembled to the optical pickup will be described with reference to the drawings, and problems of the conventional configuration will be described. FIG. 6 is a schematic perspective view showing a member used for assembling a grating in a conventional optical pickup. FIG. 7 is a schematic perspective view when the configuration shown in FIG. 6 is viewed from the back side. FIG. 8 is a schematic plan view showing a structure for assembling a grating in a conventional optical pickup. In FIG. 8, reference numeral 105 denotes a light source, and reference numeral 106 denotes a light source holder that holds the light source 105.

  As shown in FIG. 6, in the conventional optical pickup, the grating 101 is fixed to a substantially central portion of a substantially cylindrical grating holder 102 using an adhesive or the like. Then, as shown in FIG. 8, the grating holder 102 and the spring 103 disposed behind the grating holder 102 are accommodated in an accommodating portion 104 formed on the base of the optical pickup, whereby the grating 101 is obtained. Is assembled into an optical pickup. The grating holder 102 and the spring 103 are not joined, and the grating holder 102 is held in the housing portion 104 in a rotatable state. However, when the phase adjustment is completed, the grating holder 102 is bonded and fixed so as not to rotate.

  As shown in FIGS. 6 and 7, the grating holder 102 includes a holding portion 102 a that holds the grating 101 and a contact surface 104 a of the housing portion 104 that has an upper surface higher than the surface of the grating 101. A fulcrum 102b in contact with each other, a through hole 102c for transmitting light, and a groove 102d for inserting an adjusting jig in phase adjustment are formed.

  The spring 103 includes two engaging portions 103a and 103b that engage with the base of the optical pickup, and a mountain-shaped elastic portion 103c that presses the grating holder 102 between the two engaging portions 103a and 103b. , Is formed. Note that a notch 103d is formed in the elastic portion 103c of the spring 103 so that light can pass therethrough.

  The conventional configuration for assembling the grating to the optical pickup is as described above. In this configuration, a load is applied to two positions of the grating holder 102 (parts indicated by broken lines in FIG. 7) by the spring 103. It has become. In such a configuration, when the grating holder 102 is rotated for phase adjustment, a position where a load is applied is shifted and a situation in which the load point is biased easily occurs. If the load point is biased during phase adjustment, the position of the grating 101 may be shifted from a desired position, which is a problem.

  In the conventional configuration, the grating holder 102 and the spring 103 are used for assembling the grating 101 to the optical pickup. However, it has been desired to reduce the number of components as much as possible because of the demand for cost reduction.

  In Patent Document 2, a cylindrical holder in which a grating is fixed and both ends are opened, a cylindrical apparatus frame side accommodating part in which the holder is rotatably accommodated, and the holder is disposed in the apparatus frame side accommodating part. There has been proposed an optical pickup having pressing means for pressing and fixing to the holder, and the pressing means is integrally formed with the holder. In the case of this configuration, the grating holder and the spring do not have to be separate parts, so that the cost can be reduced. However, in the case of the configuration of Patent Document 2, not only the holder but also the structure of the apparatus frame is complicated, and it is considered that, for example, the size management thereof becomes difficult. For this reason, in the case of the configuration of Patent Document 2, although further cost reduction can be achieved by reducing the number of parts, further improvement has been desired.

  In view of the above points, the present invention provides an optical pickup in which a structure for assembling a grating to an optical pickup can be realized at low cost, and an unbalanced load is not easily applied to a holder that holds the grating during phase adjustment of the grating. With the goal.

  To achieve the above object, the present invention provides an optical pickup comprising a light source, a grating that diffracts light emitted from the light source, and a grating holder that holds the grating. The grating holder has a through hole. A plate-like portion that is formed and has a substantially circular shape in plan view on which the grating is bonded and held, at least three protruding portions that protrude from the plate surface of the plate-like portion, and a peripheral portion of the plate-like portion, It is characterized by having at least three protruding piece portions that protrude in the opposite direction to the protruding direction and elastically deform.

  According to this configuration, since the grating holder itself has elasticity, it is not necessary to prepare a spring that is required separately from the conventional holder, and the number of members required for assembling the grating so as to be rotatable is reduced. be able to. And according to this structure, the grating holder used in order to assemble | attach a grating so that rotation adjustment is possible can be manufactured with few press processes. For this reason, the structure which attaches a grating to an optical pickup can be made low-cost. In addition, since the grating holder is provided with at least three projecting portions and projecting piece portions, an unbalanced load is hardly applied to the grating holder even when the grating holder is rotated to adjust the phase of the grating. it can.

  In the optical pickup having the above-described configuration, it is preferable that the number of the protruding portions and the protruding piece portions is the same, and that the number of the protruding portions and the protruding piece portions is three. preferable. As a result, the structure for assembling the grating to the optical pickup can be made simpler.

  In the optical pickup having the above configuration, it is preferable that the grating is bonded and held on the back side of the plate surface on which the protruding portion of the plate-like portion is formed. According to this configuration, it is possible to reduce the size of the grating holder while sufficiently securing the elasticity exhibited by the protruding piece of the grating holder.

  In the optical pickup configured as described above, it is preferable that the projecting portion has a substantially hemispherical shape. According to this configuration, the height of at least three protrusions can be easily managed, and the arrangement accuracy of the grating can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to implement | achieve the structure where a grating is assembled | attached to an optical pick-up at low cost, it is possible to provide an optical pick-up in which an unbalanced load is difficult to be applied to the holder that holds the grating when the phase of the grating is adjusted.

Schematic showing the external configuration of the optical pickup of the present embodiment The figure which shows the optical structure with which the optical pick-up of this embodiment is provided. The schematic perspective view which shows the structure of the grating holder with which the optical pick-up of this embodiment is provided. Schematic plan view showing the configuration around the accommodation section of the grating holder in the optical pickup of the present embodiment Schematic plan view of the grating holder housed in the housing section seen from the light source side The schematic perspective view which extracted and showed the member used when attaching a grating in the conventional optical pick-up Schematic perspective view when the configuration shown in FIG. 6 is viewed from the back side Schematic plan view showing the grating assembly structure in a conventional optical pickup

Hereinafter, embodiments of an optical pickup according to the present invention will be described in detail with reference to the drawings. Here, a case where the present invention is applied to an optical pickup capable of reading and writing information on a BD will be described as an example.
(Schematic configuration of optical pickup)

  First, a schematic configuration of the optical pickup according to the present embodiment will be described. 1A and 1B are schematic views showing an external configuration of the optical pickup according to the present embodiment. FIG. 1A is a schematic plan view, and FIG. 1B is a schematic side view. As shown in FIG. 1, the optical pickup 1 of the present embodiment includes a pickup base 2 and an objective lens actuator 3 mounted on the pickup base 2. Note that bearings 2 a and 2 b are provided on the left and right sides of the pickup base 2 in order to make the pickup base 2 slidable along the guide shaft 101.

  FIG. 2 is a diagram illustrating an optical configuration provided in the optical pickup according to the present embodiment. 2 is a schematic plan view when viewed from the optical disc 100 side along the focus direction (direction perpendicular to the information recording surface 100a; see FIG. 1B).

  As shown in FIG. 2, the optical pickup 1 of this embodiment includes a light source 11, a grating 12, a polarization beam splitter 13, a quarter wavelength plate 14, a collimator lens 15, a rising mirror 16, An objective lens 17, a sensor lens 18, and a light receiving element 19 are provided. Of these members, members other than the objective lens 17 are mounted on the pickup base 2 (see FIG. 1). The objective lens 17 is mounted on the objective lens actuator 3 (see FIG. 1).

  The light source 11 is a semiconductor laser that emits laser light for BD (for example, laser light having a wavelength of 405 nm band). Note that linearly polarized light is emitted from the light source 11. The laser light emitted from the light source 11 is sent to the grating 12.

  The grating 12 diffracts the laser light sent from the light source 11 and divides it into main light and two sub-lights. The reason for dividing the light into main light and sub light is to obtain a tracking error signal necessary for tracking servo control. The optical pickup 1 of the present embodiment is formed so that a tracking error signal can be obtained by using a DPP (Differential Push-Pull) method which is a known method. Laser light emitted from the grating 12 is sent to the polarization beam splitter 13.

  The polarization beam splitter 13 reflects linearly polarized light having the same polarization direction as the linearly polarized light emitted from the light source 11 and transmits linearly polarized light whose polarization direction is rotated by 90 degrees with respect to the linearly polarized light emitted from the light source 11. Is formed. Therefore, the laser beam sent from the grating 12 to the polarization beam splitter 13 is reflected by the polarization beam splitter 13. The laser beam reflected by the polarization beam splitter 13 is sent to the quarter wavelength plate 14.

  The quarter-wave plate 14 has a function of converting incident linearly polarized light into circularly polarized light and converting incident circularly polarized light into linearly polarized light. The laser beam sent from the polarization beam splitter 13 and passing through the quarter wavelength plate 14 is converted from linearly polarized light to circularly polarized light and sent to the collimating lens 15.

  The collimating lens 15 is mounted on a lens driving unit (not shown) and is movable in the optical axis direction (direction indicated by arrow A in FIG. 2). The reason why the collimating lens 15 can be moved in this way is to make the state of the laser light emitted from the collimating lens 15 be divergent light or convergent light. The reason why the light state can be changed in this way is to enable correction of spherical aberration. The laser light emitted from the collimating lens 15 is sent to the rising mirror 16.

  The rising mirror 16 is formed of a substantially rectangular parallelepiped member and has a reflecting surface 16a that is covered with a metal thin film or the like and reflects all incident laser light. The laser beam sent from the collimating lens 15 to the rising mirror 16 by the rising mirror 16 is converted in its traveling direction and sent to the objective lens 17.

  The objective lens 17 is a high NA (for example, NA = 0.85) objective lens designed for BD, and condenses the laser beam sent from the rising mirror 16 on the information recording surface 100a of the optical disc 100. To do. The laser beam condensed on the information recording surface 100a by the objective lens 17 is reflected by the information recording surface 100a.

  The objective lens 17 is mounted on the objective lens actuator 3 as described above, and is movable in the focus direction and the tracking direction (direction parallel to the radial direction of the optical disk). The objective lens 17 can be moved in the focus direction because control (focus servo control) is performed so that the focal position of the objective lens 17 always matches the information recording surface. The objective lens 17 can be moved in the tracking direction because the light spot collected by the objective lens 17 is controlled so as to always follow the track formed on the optical disc 100 (tracking servo control). is there.

  Although the configuration of the objective lens actuator 3 is not particularly limited, in the optical pickup 1 of the present embodiment, a lens holder that holds the objective lens 17 is suspended by a wire (a rod-shaped elastic member) so as to be able to swing, and electromagnetic force The objective lens 17 can be moved in the focus direction and the tracking direction together with the lens holder using the lens holder. Since the configuration of this type of objective lens actuator is known, the detailed configuration is omitted here.

  The return light reflected by the information recording surface 100 a passes through the objective lens 17 and is reflected by the rising mirror 16. Then, after passing through the collimating lens 15, the ¼ wavelength plate 14 converts the circularly polarized light into linearly polarized light. The polarization direction of the linearly polarized light is a direction obtained by rotating the polarization direction of the linearly polarized light emitted from the light source 11 by 90 degrees. For this reason, the return light that has passed through the quarter-wave plate 14 passes through the polarization beam splitter 13. That is, the polarizing beam splitter 13 and the quarter wavelength plate 14 function as an optical isolator in cooperation with each other.

  The return light transmitted through the polarization beam splitter 13 is given a predetermined astigmatism by the sensor lens 18 and is condensed on the light receiving surface of the light receiving element 19. The light receiving element 19 converts the received optical signal into an electrical signal and outputs it, and the output electrical signal is processed to become a reproduction signal, a servo signal (focus error signal, tracking error signal, etc.) and the like.

  The sensor lens 18 may be any means for providing astigmatism. For example, a cylindrical lens or a hologram element is used. The reason why the sensor lens 18 gives a predetermined astigmatism is to obtain an astigmatism focus error signal.

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 in which the grating 12 is assembled to the pickup base 2. Specifically, the grating 12 is assembled to the pickup base 2 while being held by the grating holder, and this grating holder has a characteristic configuration. Hereinafter, the configuration of the grating holder that holds the grating 12 will be described.
(Grating holder configuration)

  FIG. 3 is a schematic perspective view showing the configuration of the grating holder provided in the optical pickup of the present embodiment. FIG. 3A is a diagram viewed from diagonally above, and FIG. 3B is a diagram viewed from diagonally below. The grating holder 20 provided in the optical pickup 1 is obtained by pressing a sheet metal member. As shown in FIG. 3, the grating holder 20 includes a plate-like portion 21 having a substantially circular shape in plan view, a protruding portion 22 protruding from the plate surface of the plate-like portion 21, and a peripheral portion of the plate-like portion 21. And a protruding piece portion 23 protruding toward the opposite side of the protruding direction of the protruding portion 22.

  Referring to FIG. 3B, a shallow groove 21a having a substantially rectangular shape in plan view for disposing the grating 12 is formed in the vicinity of the center of the plate-like portion 21 having a substantially circular shape in plan view. In addition, when referring to FIG. 3A, the groove 21 a is a protrusion that protrudes in the same direction as the protrusion 22, but the amount of protrusion is small compared to the protrusion 22. Further, a substantially U-shaped groove 21b in plan view extends from two locations around the groove 21a that is substantially rectangular in plan view (see FIGS. 3A and 3B). This substantially U-shaped groove 21b in plan view is used for filling the adhesive.

  As a procedure for bonding and fixing the grating 12, for example, the grating 12 is disposed in a groove 21a having a substantially rectangular shape in plan view, and a UV adhesive is filled in the groove 21b having a substantially U shape in plan view. A method of adhering and fixing by irradiating UV light after adjusting is adopted.

  A through hole 21c having a substantially circular shape in plan view is formed in the center of the groove 21a having a substantially rectangular shape in plan view. The through hole 21 c is provided to transmit the laser light emitted from the light source 11 and guide it to the grating 12. In addition, a cutout portion 21 d having a substantially rectangular shape in plan view is formed at one place on the peripheral edge of the plate-like portion 21. This notch 21d is used when performing phase adjustment of the grating 21 that is bonded and fixed to the grating holder 20 as will be described later.

  The protruding portion 22 is formed by pressing the plate-like portion 22, and three protruding portions 22 are provided in the present embodiment. The protruding amounts of the three protruding portions 22 are adjusted to be the same. Further, the three protrusions 22 are arranged so that the intervals between the adjacent protrusions 22 are equal. In other words, the three protrusions 22 are arranged at positions rotated approximately every 120 ° with respect to the center of the plate-like part 21 having a substantially circular shape in plan view.

  In the present embodiment, the shape of the protrusion 22 is substantially hemispherical. Thus, when the protrusion part 22 is made into a substantially hemispherical shape, it is easy to form a plane by the vertex of the three protrusion parts 22. For this reason, it becomes easy to arrange the grating 12 held by the grating holder 12 on the pickup base 2 with high accuracy. As will be described later, the protrusion 22 serves as a fulcrum.

  The projecting piece 23 is formed by bending a substantially rectangular plate piece extending from the peripheral portion of the plate-like portion 21 having a substantially circular shape in plan view at an obtuse angle. In the present embodiment, three projecting piece portions 23 are formed, but all have the same shape. Referring to FIG. 3A, all of the three protruding piece portions 23 are formed at positions shifted counterclockwise from the position where the protruding portion 22 is formed. The three protruding piece portions 23 are arranged so that the intervals between the adjacent protruding piece portions 23 are equal to each other, like the protruding portion 22. In other words, the three projecting pieces 23 are arranged at positions rotated approximately every 120 ° with respect to the center of the plate-like portion 21 having a substantially circular shape in plan view.

  Each protrusion 23 is elastically deformed when a load is applied in a direction substantially perpendicular to the plate surface of the plate-like portion 21, and serves as a so-called leaf spring. Moreover, the front end side of the projecting piece 23 is bent at an acute angle, and the front end is not rounded but rounded. This is to prevent damage to the member that comes into contact with the tip of the projecting piece 23.

  The grating holder 20 formed as described above can be formed by, for example, two pressing processes, and can be manufactured by a small number of pressing processes. Therefore, the grating holder 20 can be manufactured at low cost. Next, a configuration in which the grating 12 is assembled to the optical pickup 1 using such a grating holder 20 will be described.

(Grating assembly structure)
FIG. 4 is a schematic plan view showing a configuration around the accommodating portion of the grating holder in the optical pickup of the present embodiment. FIG. 5 is a schematic plan view of the grating holder accommodated in the accommodating portion as viewed from the light source side. In FIG. 5, the side wall 2c which is a part of the pickup base 2 is not shown. In FIG. 5, reference numeral 30 denotes a light source holder that holds the light source 11.

  As shown in FIG. 4, the grating holder 20 is accommodated in the grating accommodating portion 4 having a substantially rectangular shape in plan view. In addition, this accommodating part 4 is integrally formed in the pick-up base 2 formed with resin. Although not shown, through-holes are formed in the side walls 2c and 2d constituting the accommodating portion 4, so that the laser light emitted from the light source 11 passes through the grating 12 and further reaches the polarization beam splitter 13. It has become.

  In the grating holder 20, the apexes of the three projecting portions 22 abut against the contact surface 4a (the surface constituting the side wall 2c), and the tips of the three projecting pieces 23 are on the contact surface 4b (the surface configuring the side wall 2d). It accommodates in the accommodating part 4 so that it may contact | abut. As described above, the protruding piece portion 23 of the grating holder 20 has an elastic force, and the grating holder 20 is accommodated in a state where the protruding portion 22 is pressed against the abutting surface 4a of the accommodating portion 4 by elastic deformation of the protruding piece portion 23. Part 4 is accommodated. That is, the protruding portion 20 of the grating holder 20 functions as a fulcrum.

  Further, as shown in FIG. 5, the accommodating portion 4 is formed with a pair of inclined surfaces 4 c that are symmetrically arranged in a state of facing each other. The grating holder 20 is accommodated in the accommodating portion 4 so that the plate-like portion 21 formed in a substantially circular shape in plan view comes into contact with the pair of inclined surfaces 4c.

  The grating holder 20 accommodated in the accommodating portion 4 is rotated by inserting a rod-shaped adjusting jig (not shown) into the notch portion 21d in order to adjust the phase of the grating 12. This rotation adjustment is performed while pressing the plate-like portion 21 of the grating holder 20 against the pair of inclined surfaces 4c using an adjustment jig. Thereby, it can suppress that the rotating shaft of the grating holder 20 shakes at the time of rotation adjustment of the grating holder 20. FIG.

  When the rotation adjustment is completed, the grating holder 20 is bonded and fixed so as not to move. In the case of this embodiment, the amount of rotation of the grating holder 20 is restricted to a constant amount because of contact between the projecting piece portion 23 of the grating holder 20 and the wall surface of the accommodating portion 4, but this is performed for phase adjustment. The amount of rotation of the grating holder 20 is not so large, and this is not a problem. However, if the amount of rotation is to be increased, the configuration of the accommodating portion 4 may be changed as appropriate.

  As described above, when the grating 12 is assembled to the optical pickup 1, only the grating holder 20 can serve as the conventional holder 102 and the spring 103 (see FIG. 6). Moreover, the grating holder 20 can be formed by a few pressing processes using a sheet metal member. Furthermore, the structure of the accommodating portion 4 that accommodates the grating holder 20 is not particularly complicated as compared with the conventional case. For this reason, the optical pickup 1 of the present embodiment can be manufactured at low cost.

  In addition, the grating holder 20 of the present embodiment is devised in the configuration of the protruding portion 22 and the protruding piece portion 23 so that the balance of the load applied when the protruding piece portion 23 is elastically deformed is uniform. For this reason, it is possible to suppress a situation in which the load point is biased when the rotation of the grating holder 20 is adjusted, and as a result, the grating 12 is displaced.

(Other)
The scope of application of the present invention is not limited to the configuration of the embodiment described above. Various modifications can be made to the configuration of the embodiment described above without departing from the object of the present invention.

  For example, in the embodiment described above, the number of the protrusions 22 and the protrusions 23 included in the grating holder 20 is three. However, the number of the projecting portions 22 and the projecting piece portions 23 is not limited to three, although at least three are required. Moreover, the number of the protrusion parts 22 and the protrusion piece parts 23 may not be the same. That is, as an example, the configuration may be such that there are three protrusions 22 and five protrusions 23. However, the number of the projecting portions 22 and the projecting piece portions 23 is preferably as small as possible so that the configuration is not complicated, and it is more preferable that all of them are three as in this embodiment.

  In the embodiment described above, the protrusion 22 provided in the grating holder 20 has a substantially hemispherical shape. However, the shape is not limited to this shape, and the shape may be changed as appropriate as long as it functions as a fulcrum. It doesn't matter.

  In the embodiment described above, the grating holder 20 is configured to hold the grating 12 on the surface side opposite to the plate surface on which the protruding portion 22 is formed. However, the present invention is not limited to this configuration, and the grating 12 may be held on the side of the plate surface on which the protruding portion 22 is formed. However, the configuration as in the present embodiment is preferable because the size can be reduced while ensuring the necessary elastic force. This point will be explained in a little more detail.

  For example, when the width of the accommodating portion 4 (pointing up and down in FIG. 4) is limited, if the grating 12 is joined and held on the plate surface side where the protruding portion 22 is formed, the protruding piece portion 23 is provided. It is necessary to shorten the length of the. In this case, the elastic force of the grating holder 20 may be insufficient. On the other hand, if the elastic force is to be secured, the length of the projecting piece 23 needs to be increased, so that the grating holder 20 is increased in size. Furthermore, if the grating 20 is configured to be bonded and held on the plate surface side on which the protruding portion 22 is formed, it is necessary to increase the protruding amount of the protruding portion 22, and in this case, it is necessary to increase the size of the plate-like portion 21. May occur. As a result, the grating holder 20 may be increased in size. For this reason, the configuration in which the grating 12 is held on the side opposite to the plate surface on which the protruding portion 22 is formed as in the present embodiment is preferable because the grating holder 20 can be reduced in size.

  In the embodiment described above, the contact surface of the protrusion 22 of the grating holder 20 is the side wall 2 c of the pickup base 2. However, the present invention is not limited to this configuration. For example, the light source holder 30 that holds the light source 11 may be used as a contact surface of the protruding portion 22. Further, the arrangement of the grating holder 20 is opposite to the configuration of the present embodiment, the protrusion 22 contacts the contact surface on the polarizing beam splitter 13 side, and the tip of the projecting piece 23 is the contact surface on the light source 11 side. You may make it contact | abut.

  In addition, in the above description, the optical pickup is BD-compatible. However, the present invention is not limited to BD-compliant, and the present invention can be applied to optical pickups compatible with other types of optical disks.

  The present invention is suitable for an optical pickup of a type in which a grating is held and assembled with a holder, such as a BD compatible optical pickup.

DESCRIPTION OF SYMBOLS 1 Optical pick-up 11 Light source 12 Grating 20 Grating holder 21 Plate-shaped part 21c Through-hole 22 Projection part 23 Projection piece part

Claims (5)

A light source;
A grating that diffracts light emitted from the light source;
A grating holder for holding the grating;
In an optical pickup comprising:
The grating holder is
A plate-like portion having a substantially circular shape in plan view in which a through hole is formed and the grating is bonded and held;
At least three protruding portions protruding from the plate surface of the plate-shaped portion;
Projecting from the peripheral edge of the plate-like part to the opposite side of the projecting direction of the projecting part, and at least three projecting piece parts elastically deformed;
An optical pickup comprising:   The optical pickup according to claim 1, wherein the number of the protruding portions and the number of protruding piece portions are the same.   The optical pickup according to claim 2, wherein the number of the projecting portions and the projecting piece portions is three.   4. The optical pickup according to claim 1, wherein the grating is bonded and held on a back surface side of a plate surface on which the protruding portion of the plate-like portion is formed. 5.   The optical pickup according to claim 1, wherein the protruding portion has a substantially hemispherical shape.

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