JP2009151846A - Optical pickup - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely adjust the position of a diffraction grating by stabilizing its pressing way. <P>SOLUTION: In the optical pickup, a diffraction grating GRT is disposed in the grating hole 6 of a slide base 3, and a pressing spring 8 constituted of a ring part 8a abutted on the open side end surface 14 of the diffraction grating GRT, a pair of arm parts 8b integrally disposed in both ends of an outer peripheral edge of the ring part 8a away from each other by 180° to protrude, and inserted from respective horizonal grooves 12 into vertical holes 13, and a pair of stopper pieces 8c cut out from the vicinity of the tip of the arm parts 8b and engaged with the backside of an upright frame 4, is provided. A pair of columnar bodies 17 roughly semicircular in cross-section are integrally formed on the open side end surface 14 of the diffraction grating GRT facing both ends 8A of the ring part 8a along a center line S passing through the center of both arm parts 8b from the center O3 of the ring part 8a of the pressing spring 8, and the ring part 8a is brought into line-contact with each columnar member 17 on a center line S. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to an optical pickup used in a disk device (for example, a DVD recorder, a DVD player, etc.), and more particularly, to stabilize the way of holding a diffraction grating and to adjust its position precisely. .

FIG. 7 and FIG. 8 show disk devices, FIG. 7 is a schematic plan view of the same, and FIG. 8 is a perspective view of the optical pickup.

As shown in FIGS. 7 and 8, a slide base 3 is engaged with a pair of left and right guide rails 2 along the radial direction of a disk D arranged in the housing 1 so as to be able to reciprocate a and b. The reading light receiving element PD1 made of a photodiode, the light receiving element PD2 for detecting the light amount, and a laser light source LD made of a laser diode are disposed in the standing frame 4 formed integrally with the polarizing beam splitter PBS in the standing frame 4. And half mirror HM and objective lens O
L and a diffraction grating GRT are arranged.

Explaining the information reading procedure, the laser light LDa is projected from the laser light source LD onto the disk D rotating at high speed through the diffraction grating GRT, the polarization beam splitter PBS, the half mirror HM and the objective lens OL, and the reflected light is projected to the objective lens OL. Then, light is received by the light receiving element PD1 for reading through the half mirror HM and the polarization beam splitter PBS, and the information recorded on the disk D is read. The light amount detection light receiving element PD2 detects the projection light amount of the laser light source LD, and the control unit of the disk device adjusts the projection light amount of the laser light source LD based on the detection signal.

The main part of the conventional optical pickup will be described with reference to FIGS. 9 to 12. FIG. 9 (a) is a side view of the main part, FIG. 9 (b) is an EE arrow view, and FIG. 9 (c). FIG. 10 is an exploded perspective view of the main part, FIGS. 11A and 11B are cross-sectional views showing the fixing procedure of the diffraction grating, and FIG.
(a) And (b) is a cross-sectional view which shows the fixed state of the diffraction grating.

As shown in FIGS. 9 and 10, the reference end face 4 for arranging the laser light source LD of the standing frame 4.
A grating hole 6 is formed in a, and a diffraction grating GRT is disposed in the grating hole 6, and the diffraction grating GR
A holding spring 8 is provided for pressing T against the bottom surface 6 a with the through holes 7 of the lattice holes 6. A concave groove 9 is formed along the axis O <b> 1 on the outer peripheral surface of the diffraction grating GRT, and a concave portion 10 is formed in the standing frame 4 so as to face the concave groove 9.

As shown in FIGS. 9 and 10, a pair of lateral grooves 12 extending in opposite directions from the outer peripheral edge of the lattice hole 6 are formed on the reference end surface 4 a, and a pair that penetrates the standing frame 4 from the back end of each lateral groove 12. A vertical hole 13 is formed.

As shown in FIGS. 9 and 10, the holding spring 8 includes a ring portion 8a that is in contact with the open end surface 14 of the diffraction grating GRT in the grating hole 6, and an outer portion of the ring portion 8a that is 180 ° apart from each other. A pair of substantially U-shaped arm portions 8b which are integrally provided at both ends of the peripheral edge and are inserted from the respective lateral grooves 12 into the respective vertical holes 13, and are cut out from the vicinity of the distal ends of the respective arm portions 8b and engaged with the back surface of the standing frame 4. The arm portions 8b are elastically displaced to generate downward tensile forces F1 and F2 (see FIG. 9B), and the tensile forces F1 and F2 Ring part 8a
Is pressed against the open end surface 14 of the diffraction grating GRT so that the diffraction grating GRT does not rotate unexpectedly.

The procedure for positioning and fixing the diffraction grating GRT will be described below. As shown in FIG. 11A, the operation shaft 15 is inserted into the recessed portion 10 of the upright frame 4, and the eccentric shaft 15a integrally projecting from the tip of the operation shaft 15 is provided.
Is inserted into the concave groove 9 of the diffraction grating GRT, the operation shaft 15 is rotated forward and backward around the axis O2, and the inner surface of the concave groove 9 is pressed by the eccentric shaft 15a, whereby the diffraction grating GRT is moved to the axis O1. It is rotated in the directions of arrows c and d around and finely adjusted so that the laser beam LDa passing through the diffraction grating GRT is dispersed as desired.

Subsequently, as shown in FIG. 11B, the ultraviolet curable adhesive UV is filled from the concave portion 10 to the concave groove 9 by an adhesive filling device (not shown), irradiated with ultraviolet rays, and the ultraviolet curable properties thereof are irradiated. The diffraction grating GRT is fixed to the upright frame 4 by curing the adhesive UV. In addition, there exists what was described in patent document 1 as a technique relevant to this invention.
Japanese Patent Laid-Open No. 2004-22034

In the above conventional configuration, the ring along the center line S passing from the center O3 of the ring portion 8a to the center of the both arm portions 8b by the tensile forces F1 and F2 generated by elastically displacing the both arm portions 8b of the holding spring 8. Both end portions 8A of the portion 8a (see FIG. 9A) are pressed against the open-side end surface 14 of the diffraction grating GRT in an almost balanced manner by surface contact.

However, in practice, both tensile forces F1, F1 are caused by dimensional errors and distortions of the holding spring 8 and the upright frame 4.
An imbalance may occur in the pressure value of F2, and as a result, as shown in FIG. 12A, the ring portion 8a is inclined by a small angle α along the center line S, or as shown in FIG. In addition, the ring portion 8a may be inclined by a small angle β along the direction orthogonal to the center line S. In this case, it is not known which portion of the ring portion 8 is pressed against the diffraction grating GRT, and the pressing method is not good. It is stable.

As described above, if the method of holding the diffraction grating GRT is unstable, when the diffraction grating GRT is fixed with the ultraviolet curable adhesive UV, the diffraction grating GRT is caused by solidification shrinkage of the ultraviolet curable adhesive UV. Does not know in which direction the arrows c and d are displaced [FIG. 11 (a)
Also, in the environmental tests (high and low temperature, high and low humidity, etc.), the diffraction grating GRT is in the direction of arrows c and d due to the difference in thermal expansion coefficient between the UV curable adhesive UV and the diffraction grating GRT. It is not known whether the position is shifted (see FIG. 11A).

In short, in the above configuration, since the position shift direction and the position shift width of the diffraction grating GRT cannot be predicted and corrected in advance, the laser beam LDa passing through the diffraction grating GRT is precisely distributed as desired. It is difficult to set.

The present invention has been made in view of the above-described conventional drawbacks, and an object of the present invention is to provide an optical pickup that can stabilize the way of holding a diffraction grating and precisely adjust its position.

In order to achieve the above object, according to the first aspect of the present invention, an upright frame is integrally formed on a slide base that can reciprocate along the radial direction of the disk. A pair of horizontal grooves extending in opposite directions from the outer peripheral edge and a pair of vertical holes penetrating the standing frame from the back end of each horizontal groove are formed, and a diffraction grating is disposed in the grating hole to hold the diffraction grating The holding springs are provided integrally with the ring portion that is in contact with the open end face of the diffraction grating in the grating hole and at both ends of the outer peripheral edge of the ring portion that are 180 ° apart from each other. Each arm portion is formed by a pair of arm portions inserted from the lateral grooves into the respective vertical holes, and a pair of stopper pieces cut out from the vicinity of the front ends of the respective arm portions and engaged with the back surface of the standing frame. Generated by elastic displacement of After pressing the ring part against the open end face of the diffraction grating with tension and finely adjusting the position of the diffraction grating, the diffraction grating is fixed to the standing frame with an adhesive, and the laser beam from the laser light source passes through the diffraction grating to the disk. In the optical pickup that receives the reflected light and reads the information recorded on the disk, both end portions of the ring portion along the center line passing from the center of the ring portion to the center of both arm portions A pair of interposition members are interposed between the open end face of the diffraction grating opposite to both ends thereof, and the ring portion is pressed against the open end face of the diffraction grating via both of the interposition members. It is a feature.

The invention according to claim 2 is the invention according to claim 1, wherein the pair of interposing members is formed of a columnar body having a substantially semicircular cross section formed integrally with the open end face of the diffraction grating, The ring portion is in line contact with the body on the center line.

According to a third aspect of the present invention, in the first aspect of the invention, the pair of interposed members are formed of hemispheres having a substantially semicircular cross section formed integrally with the open side end surface of the diffraction grating, and each hemisphere. The ring portion is point-contacted with the body on the center line.

According to the first aspect of the present invention, both end portions of the ring portion of the pressing spring are pressed against the diffraction grating via the pair of interposition members, the pressing position is constant, and the pressing method is stable. Therefore, it is possible to predict the misalignment direction and misalignment width of the diffraction grating due to solidification shrinkage of the adhesive and environmental tests (high and low temperature, high and low humidity, etc.). Therefore, based on the prediction, the position adjustment before fixing by the adhesive of the diffraction grating can be corrected, and the laser light passing through the diffraction grating can be precisely set so as to be dispersed as desired.

According to the second aspect of the present invention, since both ends of the ring part are in line contact with the columnar bodies of the diffraction grating on the center line passing from the center of the ring part to the center of both arm parts, Tensile force due to the elastic displacement is intensively applied to the diffraction grating via each columnar body, and the diffraction grating can be reliably pressed in a predetermined manner.

According to the second aspect of the present invention, since both ends of the ring portion are point-contacted with the respective hemispheres of the diffraction grating on the center line passing from the center of the ring portion to the center of both arm portions, Tensile force due to the elastic displacement is applied to the diffraction grating more intensively through the respective hemispheres, and the diffraction grating can be reliably pressed in a predetermined manner.

1 to 3 show an optical pickup according to a first embodiment of the present invention. FIG. 1A is a side view of the main part, and FIG. FIG. 1 (c) is a view taken along the line B-B, FIG. 2 is an exploded perspective view of the main part, and FIGS. 3 (a) and 3 (b) are cross-sectional views showing a fixed state of the diffraction grating.

As shown in FIGS. 1 to 3, on the open side end face 14 of the diffraction grating GRT facing both ends 8A of the ring portion 8a along the center line S passing through the center of the both arm portions 8b from the center O3 of the ring portion 8a. A pair of columnar bodies (intervening members) 17 having a substantially semicircular cross section are integrally formed, and the ring portion 8 a is in line contact with the columnar bodies 17 on the center line S. Since the configuration other than the above is substantially the same as the configuration shown in FIGS. 7 to 11, the same parts are denoted by the same reference numerals and the description thereof is omitted.

According to the said structure, as shown to Fig.3 (a) and (b), the ring part 8a of the presser spring 8 is shown.
Both end portions 8A are pressed against the diffraction grating GRT through a pair of columnar bodies 17, the pressing position is constant, and the pressing method is stable. The misalignment direction and misalignment width of the diffraction grating GRT can be predicted by solidification shrinkage and environmental tests (high and low temperature, high and low humidity, etc.). Therefore, based on the prediction, the diffraction grating GR
The position adjustment of T before fixing with the UV curable adhesive UV can be corrected, and the laser light LDa passing through the diffraction grating GRT can be precisely set to be dispersed as desired.

Further, both end portions 8A of the ring portion 8a are in line contact with the columnar bodies 17 of the diffraction grating GRT on the center line S passing through the center of the both arm portions 8b from the center O3 of the ring portion 8a. Tensile forces F1 and F2 due to the elastic displacement of 8b are intensively applied to the diffraction grating GRT via the columnar bodies 17, and the diffraction grating GRT can be reliably pressed as predetermined.

4 to 6 show an optical pickup according to a second embodiment of the present invention. FIG. 4 (a) is a side view of the main part, and FIG. 4 (b) is a view taken along the line CC. FIG. 4 (c) is a DD arrow view, FIG. 5 is an exploded perspective view of the main part, and FIGS. 6 (a) and 6 (b) are cross-sectional views showing a fixed state of the diffraction grating.

As shown in FIGS. 4 to 6, on the open-side end face 14 of the diffraction grating GRT facing both ends 8A of the ring portion 8a along the center line S passing through the center of the both arm portions 8b from the center O3 of the ring portion 8a. A pair of semispherical bodies (intervening members) 18 having a substantially semicircular cross section are integrally formed, and the ring portion 8a is in line contact with each hemispherical body 18 on the center line S. Since the configuration other than the above is substantially the same as the configuration shown in FIGS. 7 to 11, the same parts are denoted by the same reference numerals and the description thereof is omitted.

According to the above configuration, substantially the same effect as that of the first embodiment shown in FIGS. 1 to 3 can be obtained, and particularly on the center line S passing from the center O3 of the ring portion 8a to the center of both arm portions 8b. Since both end portions 8A of the ring portion 8a are in point contact with the respective hemispheres 18 of the diffraction grating GRT, the tensile forces F1 and F2 due to the elastic displacement of the respective arm portions 8b are passed through the hemisphere 18 through the diffraction grating GRT. The diffraction grating GRT can be reliably pressed as prescribed.

In the first and second embodiments, a pair of columnar bodies 17 or hemispheres 18 that are interposition members are integrally formed on the open-side end face 14 of the diffraction grating GRT, and the ring portion 8a is formed on the columnar body 17 or hemisphere 18. However, the present invention is not limited to this, and contrary to the above,
An interposition member may be integrally formed at both end portions 8A of the ring portion 8a, and the open end surface 14 of the diffraction grating GRT may be brought into contact with the interposition member.

(A) is a side view of the principal part which shows the optical pick-up which is the 1st Embodiment of this invention, (b) is an AA arrow directional view, (c) is a BB arrow directional view. It is a disassembled perspective view of the principal part. (A) And (b) is a cross-sectional view which shows the fixed state of the diffraction grating. (A) is a side view of the principal part which shows the optical pick-up which is the 2nd Embodiment of this invention, (b) is CC arrow directional view, (c) is DD arrow directional view. It is a disassembled perspective view of the principal part. (A) And (b) is a cross-sectional view which shows the fixed state of the diffraction grating. It is a schematic plan view showing a disk device. It is a perspective view of the optical pickup. (A) is a side view of the principal part of a prior art example, (b) is an EE arrow view, (c) is an FF arrow view. It is a disassembled perspective view of the principal part. (A) And (b) is a cross-sectional view which shows the fixation procedure of the diffraction grating. (A) And (b) is a cross-sectional view which shows the fixed state of the diffraction grating.

Explanation of symbols

3 Slide Base 4 Standing Frame 4a Reference End Face of Standing Frame 6 Lattice Hole 8 Holding Spring 8a Holding Spring Ring 8b Holding Spring Arm 8c Holding Spring Stopper 8A Ring End 12 Horizontal Groove 13 Vertical Hole 14 Diffraction Grating Open side end face 17 Columnar body (intervening member)
18 Hemisphere (intervening member)
O3 Center of ring part GRT Diffraction grating UV UV curable adhesive S Center line D Disc LD Laser light source

Claims (3)

A standing frame is integrally formed on a slide base that can reciprocate along the radial direction of the disk.
A lattice hole, a pair of lateral grooves extending in opposite directions from the outer peripheral edge of the lattice hole, and a pair of vertical holes penetrating the standing frame from the back end of each lateral groove are formed in the standing frame. And a holding spring for holding the diffraction grating. The holding spring is in contact with the open end face of the diffraction grating in the grating hole, and the ring part is mutually 180 °. A pair of arm portions projecting integrally at both ends of the outer peripheral edge separated from each other and inserted through the vertical holes from the respective lateral grooves, and a pair of portions cut out from the vicinity of the distal ends of the respective arm portions and engaged with the back surface of the standing frame The ring part is pressed against the open end face of the diffraction grating with the tensile force generated by elastically displacing each arm part, and the position of the diffraction grating is finely adjusted. Fix the grid to the standing frame with adhesive and In an optical pickup that projects laser light from a light source through a diffraction grating onto a disk and receives the reflected light to read information recorded on the disk, the center of both arms from the center of the ring part A pair of interposition members are interposed between both end portions of the ring portion along the center line passing through and the open side end surface of the diffraction grating facing the both end portions, and the ring portion is diffracted via both interposition members. An optical pickup, wherein the optical pickup is pressed against an open end face of the grating. The pair of interposition members are formed of columnar bodies having a substantially semicircular cross section integrally formed on the open end face of the diffraction grating, and the ring portions are in line contact with the respective columnar bodies on the center line. The optical pickup according to claim 1. The pair of interposition members are formed of hemispheres having a substantially semicircular cross section integrally formed on the open end face of the diffraction grating, and the ring portions are point-contacted with the hemispheres on the center line. The optical pickup according to claim 1.

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