JP2000285494A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device equipped with a mechanism for easily and accurately operating the phase adjustment of grating which diffracts outgoing laser beams. SOLUTION: In the light source unit of an optical pickup device, a holder 22 whose top end is provided with a grating 3 is inserted into a housing part 21 formed at a device frame 20, and this holder 22 is pressurized by a coil spring 23 in a compressed state with a spacer 30 interposed. At the time of rotating the holder 22 with an optical axis L as a center for the phase adjustment of the grating 3, the coil spring 23 is not directly brought into contact with a holder rear end face 22c, so that the problem of the interruption of the smooth rotation of the holder 22 or the problem of the rotation of the holder 22 after the phase adjustment due to an acting face from the coil spring 23 can be prevented. Thus, the phase adjustment of the grating can be easily and accurately attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for performing a reproducing operation of a recording medium such as a CD and a DVD, and more particularly, to an improvement in a mounting portion of a grating incorporated for generating a tracking error signal and the like. It is about.

[0002]

2. Description of the Related Art Generally, an optical system of an optical pickup device used for reproducing and recording information from a recording medium such as a CD or a DVD includes a laser diode as a laser light source and a laser beam emitted from the laser diode. And an objective lens that focuses the diffracted light onto the optical recording medium, and a photodetector that receives the return light from the optical recording medium via the objective lens. These optical components are mounted on an apparatus frame, for example, as described in Japanese Patent Application Laid-Open No. 10-11778.

Here, for example, the grating can be moved in the optical axis direction of the laser beam with respect to the device frame and rotated about the optical axis so that the position adjustment between the optical components can be performed. Mounted as possible,
After adjusting the position in the optical axis direction and the rotational position, it is fixed to the device frame side with an adhesive or the like.

[0004]

As a mechanism for adjusting the mounting position of the grating, a structure shown in FIG. 3 can be considered. In this mechanism, a cylindrical holder 103 with a grating 102 attached to the tip is inserted coaxially from one end opening of a cylindrical housing portion 101 formed in a device frame 100 of an optical pickup device. , The laser diode 105 is inserted coaxially.

On the outer periphery of the grating 102 attached to the tip of the holder 103, positioning projections 103b are provided at equal angular intervals from the annular end face 103a of the holder 103.
Protrudes forward. When the laser diode 105 is inserted and fixed in the opening of the housing 101, the holder 103 is pushed forward by the spring force of the coil spring 104 sandwiched between the laser diode 105 and the rear end face of the holder, and the tip of the holder 103 is positioned. The tip of the projection 103b for
An annular end face 1 formed at the front end opening of the device frame side storage portion
01a. Therefore, the spacer 106 is provided between the positioning projection 103b and the annular end face 101a on the apparatus frame side.
, The position of the grating 102 attached to the tip of the holder 103 in the optical axis direction can be adjusted.

[0006] The holder 103 has a cylindrical housing 101.
The jig such as an eccentric pin is inserted through the through hole 101b opened in the housing portion 101, and the inner holder 103 is rotated, thereby rotating the grating 103 attached to the holder 103. The phase can be adjusted, and the grating is positioned at the adjusted position by fixing the holder 102 with an adhesive or the like after the phase adjustment.

However, the grating positioning mechanism having this configuration has the following problems to be solved.

[0008] First, the phase adjustment work of the grating,
This is performed by rotating the holder on which the grating is mounted while the pressing force of the coil spring is applied. In this operation, the end face of the holder is in direct contact with the coil spring. For this reason, when rotating and adjusting the holder, a return force acts from the side of the coil spring that is in contact with the end face of the holder. Therefore, the holder cannot be rotated smoothly. In other words, it is difficult to adjust the phase of the grating.

When the holder is left after the holder is rotated and the phase of the grating is adjusted, the elastic return force of the coil spring acts as a rotational force on the holder. As a result, the holder may rotate from the position after the phase adjustment, and the phase may be shifted again.

[0010] Here, since the holder is generally a resin molded product, the end surface in contact with the coil spring has an uneven shape after the knock pin at the time of molding. The edges are easily caught. For this reason, the above adverse effects are likely to occur.

[0011] The object of the present invention is to solve the above problems.
An object of the present invention is to propose an optical pickup device including a mechanism that can accurately adjust the phase of a grating by a simple operation.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a grating for diffracting a laser beam emitted from a laser light source, a holder to which the grating is fixed, and a movable holder. In an optical pickup device having a device frame-side receiving portion accommodated therein and a coil spring pressing and fixing the holder against the device frame-side receiving portion, a spacer is sandwiched between the holder and the coil spring. It is characterized by having been.

[0013] The spacer prevents contact of the coil spring with the holder. Therefore, the elastic return force of the coil spring is not transmitted to the holder. In addition, the end of the coil spring is prevented from being caught on the unevenness of the end face of the holder. As a result, adverse effects caused by the coil spring can be avoided.

Here, the holder may be a cylindrical member that is movable in the optical axis direction of the laser light with respect to the housing portion on the apparatus frame side and is rotatably housed around the optical axis. it can. In this case, the laser light source, the coil spring, the spacer, and the holder are arranged coaxially in this order along the optical axis direction of the laser light, and the holder is housed by the coil spring in the apparatus frame. By pressing the holder, the position of the holder in the optical axis direction can be defined.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical pickup device to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an optical system of the optical pickup device of this embodiment, and FIG. 2 is an enlarged sectional view showing the light source unit in an enlarged manner. The optical system of the optical pickup device 1 includes a light source unit 4 including a laser diode 2 and a grating 3, and a beam splitter 5 for separating laser light emitted from the light source unit 4 from return light from the optical recording medium 10. And the light source unit 4
Collimating lens 6 that converts the laser beam from the lens into parallel light
And collimated light from the collimating lens 6 into the optical recording medium 10.
Is provided with an objective lens 7 for focusing on the recording surface. Further, a photodetector 9 for receiving return light from the optical recording medium 10 via the sensor lens 8 is provided.

Next, the light source unit 4 includes a cylindrical housing 2 formed on the device frame 20 of the optical pickup device 1.
1, a cylindrical holder 22 inserted coaxially from the one end opening 21a, a grating 3 attached to the tip of the cylindrical holder 22, and a coil spring 23. It has a laser diode 2 inserted. The holder 22
The size is such that it is movable in the direction of the optical axis L and is rotatable about the optical axis L.

On the outer periphery of the grating 3 attached to the tip of the cylindrical holder 22, a positioning projection plate 22b protrudes forward from the annular end face 22a of the holder 22 at equal angular intervals. For example, four protruding plates 22b protrude at 90 degree intervals. When the laser diode 2 is inserted into the housing portion 21 and fixed to the housing portion 21 with an adhesive or the like, the holder 22 is pressed by the spring force of the coil spring 23 sandwiched between the laser diode 2 and the annular holder rear end surface 22c. Is pushed forward, and the front end of the positioning projection plate 22b at the front end is pushed into the device frame side housing portion 21.
End face 21c of annular projection 21b formed at the front end opening of
Hit. Therefore, by sandwiching the positioning spacer 25 between the positioning projection plate 22b and the annular end surface 21c, the position of the grating 3 attached to the tip of the holder 22 in the direction along the optical axis L can be adjusted.

Here, in the light source unit 4 of this embodiment, the front end 23a of the coil spring 23 and the rear end face 22 of the holder
c, a disk-shaped spacer 30 is sandwiched. The spacer 30 is a molded product made of, for example, a synthetic resin material, has an outer diameter dimension substantially matching the inner diameter dimension of the housing portion 21, and has a circular light passage hole 31 for laser light passage formed at the center. I have. Further, both surfaces of the spacer 30 are smooth flat surfaces having a small coefficient of friction.

A through hole 21 is formed in the outer peripheral wall of the cylindrical accommodation portion 21.
e is formed, and a groove 22e extending in the direction of the optical axis L is formed in a portion of the outer peripheral surface of the holder 22 facing the through hole 21e.

The procedure for adjusting the position of the light source unit 4 for assembling the grating 3 in the optical pickup device 1 according to the present embodiment thus configured will be described. A positioning spacer 25, a holder 22 to which the grating 3 is attached, a coil spring 23,
The laser diode 2 is inserted in this order, and the position of the grating 3 in the direction of the optical axis L is adjusted. This adjustment can be performed by an operation such as replacing the positioning spacer 25 with one having a predetermined thickness.

Next, a jig such as an eccentric pin is inserted through a through hole 21e opened in the housing portion 21, and the inner holder 22 is rotated about the optical axis L to thereby obtain the holder 2.
Rotation position of grating 3 attached to 2,
That is, the phase is adjusted.

Here, in the light source unit 4 of the present embodiment, the spacer 30 is sandwiched between the holder 22 and the coil spring 23. Therefore, since the coil spring 23 does not directly contact the end face of the holder 22, the holder 22 cannot be rotated smoothly due to the pressing force of the coil spring 23 in a compressed state when the phase of the holder 22 is adjusted. No harm occurs. Further, the elastic return force of the coil spring 23 in the compressed state is not directly transmitted to the holder 22 as the rotational force of the holder 22. Therefore, the disadvantage that the holder 22 after the phase adjustment rotates around the optical axis L due to the elastic return force of the coil spring and the phase shifts can be avoided. Furthermore, since both end surfaces of the spacer 30 are flat and smooth, even if the spacer is rotated by the coil spring, a slip does not occur between the spacer and the end surface of the holder, and the holder does not rotate.

After the position of the grating 3 in the direction along the optical axis L and the position in the rotational direction about the optical axis L are adjusted as described above, the components are fixed by an adhesive or the like. Thus, the assembling work of the light source unit 4 is completed.

(Other Embodiments) The above-described optical pickup device includes a light source unit 4 having a configuration in which a laser diode and a holder to which a grating is mounted are housed in a common housing. However, the present invention is, of course, similarly applicable to an optical pickup device having a configuration in which only a holder having a grating attached at the tip end, separately from a laser diode, is mounted in a storage portion formed in the device frame. is there.

The material and shape of the spacer 30 are as follows:
It is not limited to the above example. The shape of the spacer may be any shape as long as the coil spring and the end face of the holder do not directly contact each other. The material of the spacer may be any material that can form a surface having a small coefficient of friction.

Further, the shape of the holder 22 is not limited to the cylindrical shape as in the above-described example. For example, the shape can be such that the holder 22 can be rotated about the optical axis L by a predetermined angle range. Of course, it may be possible.

[0028]

As described above, in the optical pickup device of the present invention, the spacer is interposed between the holder holding the grating and the coil spring so that the holder and the coil spring do not come into direct contact. . Therefore, according to the present invention, it is possible to solve the problem that the phase adjustment of the grating cannot be easily performed due to the pressing force of the coil spring, and the phase after the phase adjustment is rotated by the elastic return force of the coil spring. The disadvantage of shifting can also be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an optical system of an optical pickup device to which the present invention has been applied.

FIG. 2 is a partially enlarged sectional view showing a light source unit of the optical pickup device shown in FIG.

FIG. 3 is a sectional view showing a light source unit of a conventional optical pickup device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical pickup device 2 Laser diode 3 Grating 4 Light source unit 20 Device frame 21 Housing 22 Holder 22c Rear end face of holder 23 Coil spring 23a Tip of coil spring 30 Spacer L Optical axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Zhou Ekai 5329 Shimosuwa-cho, Suwa-gun, Nagano Prefecture F-term (reference) in Sankyo Seiki Seisakusho Co., Ltd.

Claims (2)

[Claims] 1. A grating for diffracting a laser beam emitted from a laser light source, a holder to which the grating is fixed, an apparatus frame-side housing portion in which the holder is movably housed, and the holder An optical pickup device having a coil spring pressed and fixed to a device frame side accommodating portion, wherein a spacer is sandwiched between the holder and the coil spring. 2. The cylindrical member according to claim 1, wherein the holder is accommodated in the apparatus frame-side accommodating portion so as to be movable in an optical axis direction of the laser light and rotatable around the optical axis. The laser light source, the coil spring, the spacer, and the holder are coaxially arranged in this order along the optical axis direction of the laser light, and the holder allows the holder by the coil spring. An optical pickup device characterized in that a position in an optical axis direction is defined by being pressed against the optical pickup.