JPH05971Y2 - - Google Patents

Description

[Detailed Description of the Invention] The optical axis adjustment mechanism of the optical pickup device of the present invention will be explained according to the following items.

A. Industrial field of application B. Overview of the invention C. Prior art a. General background [Fig. 8] b. Optical axis adjustment mechanism in a conventional optical pickup device [Fig. 9] D. Problems to be solved by the invention [Fig. 9] [Figure] E Means for solving the problem F Example a External appearance [Figure 1] b Mirror support member [Figures 1 and 2] c Prism [Figures 1 and 2] d Holder, pressing means [Fig. 1] e Effect [Fig. 1] f Usage example [Fig. 3 to 5] g Modification example [Fig. 6, Fig. 7] G Effect of the invention (A. Industrial application field) This invention relates to an optical axis adjustment mechanism for a novel optical pickup device. Specifically, in a type of optical pickup device installed in a compact disc player, video disc player, etc., in which the beam light is bent at a substantially right angle and irradiated onto the optical disc, the beam light is irradiated onto the optical disc at a right angle. It is an object of the present invention to provide a novel optical axis adjustment mechanism for an optical pickup device that allows accurate adjustment.

(B Overview of the invention) The optical axis adjustment mechanism of the optical pickup device of the present invention includes a reflecting mirror that bends a beam of light approximately at right angles, which is provided so as to pass through the center of the spherical surface of a mirror support member having at least a portion of a spherical surface. By providing a circular reference hole in the holder supporting the mirror and arranging the spherical surface of the mirror support member to press against the reference hole, the mirror support member can be rotated in all directions, and as a result, the reflecting mirror can be rotated in all directions. The angle can be adjusted, and the beam light can be adjusted to irradiate the optical disk at a right angle.

(C Prior Art) (a General Background) [Figure 8] An optical pickup device, that is, a beam light emitted from a laser light source is irradiated onto the recording surface of an optical disk, and the reflected light is modulated on the recording surface of the optical disk. In a device that reads light, that is, returned light, as a signal, in order for the returned light to enter the optical pickup device again, the beam light emitted from the optical pickup device to the optical disk must be adjusted so that the angle of incidence with respect to the optical disk is true. It is necessary to make it at a right angle.

By the way, in recent years, optical pickup devices have been required to be made thinner by arranging a laser light source and various optical components parallel to the surface of an optical disk, emitting a beam of light parallel to the optical disk, and then using a reflecting mirror to approximately There is one in which the light beam is bent at a right angle and the light beam is irradiated onto an optical disk at a right angle through an objective lens.

FIG. 8 conceptually shows an example of such an optical pickup device a, which includes a semiconductor laser b, a phase diffraction grating c, a beam splitter d, a collimating lens e, and a reflecting mirror f. , an objective lens driving section h having an objective lens g, a concave lens section i, and a cylindrical lens section j
is equipped with a cylindrical lens k and a photodiode l integrally formed, and the beam light emitted from the semiconductor laser b is transmitted through a phase diffraction grating c.
After being split into a main beam for signal reading and a plurality of sub-beams for servo use, it passes through a beam splitter d, is made into a parallel beam by a collimating lens e, and is bent at a right angle by a reflecting mirror f. The light is focused by the objective lens g and is irradiated onto the recording surface n of the optical disk m with a spot of a predetermined diameter, and is modulated at the recording surface n and directed toward the objective lens g. After the reflected return light passes through the objective lens g, it is bent at a right angle by the reflection mirror f, further passes through the collimating lens e, and is reflected at the beam splitter d toward the cylindrical lens k. After being given a predetermined condensing property, the photodiode l is irradiated with the light, and the main beam light detects the signal recorded on the recording surface n of the optical disk m, and the main beam light and the sub-beam light are used for servo purposes. That is, signals for focusing servo and tracking servo are detected.

However, when using a reflective mirror f,
Depending on the installation accuracy of the reflecting mirror f, etc., the optical disc m
There is a possibility that the optical axis of the beam of light irradiated to the optical disk m may be tilted with respect to the optical disk m.

Therefore, in this type of optical pickup device a, it is necessary to adjust the angle of the optical axis of the beam that is bent at approximately 90 degrees and is incident on the optical disk m.

(b Optical axis adjustment mechanism in conventional optical pickup device) [FIG. 9] FIG. 9 shows a mechanism o for adjusting the angle of the optical axis of the beam light in a conventional optical pickup device.

In FIG. 9, p is a disc-shaped rotating table,
A reflecting mirror q is fixed to the rotary table p substantially in the center thereof with a reflecting surface having an angle of 45° with respect to the upper surface of the rotary table p.

r and r are arcuate long holes formed near the periphery of the rotary table p.

The turntable p is attached to a mounting holder (not shown) by inserting screws s, s into the elongated holes r, r, and screwing nuts (not shown) therein.

The beam of light emitted from the laser light source b and transmitted through each of the optical elements is bent at a substantially right angle by the reflecting mirror q, and is irradiated onto the optical disk via the objective lens.

At this time, the optical axis of the beam of light bent by the reflecting mirror q is not necessarily irradiated at a right angle to the optical disk due to the mounting precision of the reflecting mirror q.

Therefore, by rotating the rotating table p relative to the holder for attaching the objective lens, the direction of the reflecting mirror q is changed and the angle of the optical axis of the beam light is adjusted.

(Problem to be solved by the invention D) [Fig. 9] However, in the optical axis adjustment mechanism o of the conventional optical pickup device described above, since the reflecting mirror q is simply rotated on a plane, the circumferential direction The optical axis can only be adjusted at .

That is, when a beam of light is irradiated onto the reflecting mirror q of such an optical axis adjustment mechanism o and is reflected at a substantially right angle, the reflected beam of light follows an arcuate trajectory on a plane parallel to the optical disk. (Figure 9).

However, the optical axis of the reflected beam light may be shifted in any direction due to the installation of the reflection mirror q, the installation of optical components, etc.; ) alone cannot make a complete adjustment.

Therefore, in the past, it was necessary to improve the dimensional accuracy of each optical component, reflective mirror, and their mounting base, and to mount them with high precision, which made the optical pickup device extremely expensive. There was a problem.

(E. Means for Solving Problems) In order to solve the above-mentioned problems, the optical axis adjustment mechanism of the pickup device of the present invention replaces the reflecting mirror that bends the beam at a substantially right angle with a mirror having a part of a spherical surface. The holder that supports the mirror support member is provided with a circular reference hole, and the mirror support member is placed so as to be pressed against the reference hole, so that the mirror support member can be moved in any direction. It is designed so that it can rotate.

Therefore, according to the optical axis adjustment mechanism of the optical pickup device of the present invention, it is possible to adjust the angle of the reflecting mirror in all directions, and it is possible to adjust the beam light so that it irradiates the optical disk at a right angle. This makes it possible to irradiate the optical disk with a beam of light at right angles without increasing the dimensional accuracy of the optical components and the accuracy of mounting these components on the mounting base as in the prior art.

(Embodiment F) Below, the optical axis adjustment mechanism of the optical pickup device of the present invention will be explained according to Example 1 of the embodiment shown in the accompanying drawings.

(a External appearance) [Figure 1] The optical axis adjustment mechanism 1 includes a mirror support member 2 having a spherical surface in part, and a 45° prism attached to a surface passing through the spherical center O of the spherical surface of the mirror support member 2. 3, a mirror support member holder 5 provided with a reference hole 4 having a smaller diameter than the diameter of the mirror support member 2, and a pressing means 6 for pressing the mirror support member 2 against the reference hole 4 of the holder 5. The optical axis adjustment mechanism 1 is installed in an optical pickup device so that the beam light emitted from the semiconductor laser at the reflective surface 3a of the 45° prism 3 and transmitted through the required optical elements is bent at a substantially right angle toward the objective lens. It is located.

(b Mirror support member) [Figures 1 and 2] The mirror support member 2 is made of a steel ball with a groove 7 having a constant width in the diametrical direction including the center O of the ball. The other portion 8 is made into a spherical surface, and an adjustment hole 9 is bored in the surface of the mirror support member 2 opposite to the surface on which the groove 7 is formed. Note that the adjustment hole 9 is formed in a portion facing the outside when the mirror support member 2 is supported by the holder 5 as described later.

(c Prism) [Figures 1 and 2] The prism 3 is a so-called 45° prism having a right-angled isosceles triangular cross section, and its right-angled surfaces are used as reflective surfaces 3a.

The 45° prism 3 is arranged such that its reflective surface 3a is in contact with the bottom surface 7a of the concave groove 7 of the mirror support member 2, and the approximate center of the reflective surface 3a is aligned with the spherical center O of the mirror support member 2. is fixed in the groove 7.

(d Holder, Pressing Means) [Figure 1] The holder 5 consists of an upper wall 10 in which a reference hole 4 is formed and a cylindrical part 11 vertically disposed on the upper wall 10,
The cylindrical portion 11 has a space in which the mirror support member 2 is housed, and the height of the cylindrical portion 11 is slightly smaller than the diameter of the mirror support member 2.

Further, a window 12 is formed on the side of the cylindrical portion 11 to receive the beam light irradiated from the laser light source, and a lower end surface 11 of the cylindrical portion 11 is formed.
A is a plate spring 13, 1 protruding toward the center of the opening.
3 and 13 are attached.

The mirror support member 2 has its spherical surface 8 in contact with the periphery of the reference hole 4, and the reflective surface 3a of the prism 3 is at an angle of approximately 45° with respect to the reference hole 4 and the window 12 of the cylindrical portion 11, respectively. They are accommodated in the cylindrical portion 11 in the following positional relationship. The lower end of the mirror support member 2 housed in the cylindrical portion 11 comes into contact with the leaf springs 13, 13, 13,
13, 13 is biased toward the reference hole 4 side.

(e) Therefore, the spherical surface 8 of the mirror support member 2 is always pressed against the reference hole 4, and an appropriate jig is inserted into the adjustment hole 9 of the mirror support member 2. By operating the mirror support member 2, the mirror support member 2 can be rotated. When the mirror support member 2 rotates, since its spherical surface 8 is in contact with the reference hole 4, the mirror support member 2 rotates around the spherical center O of the sphere, and also rotates by 45°.
The reflective surface 3a of the prism 3 is connected to the mirror support member 2.
Since it is attached to a plane including the spherical center O, it can be rotated in all directions around the center of the reflective surface 3a.

In the first embodiment, a prism is used as the reflecting mirror, but by transmitting the beam light through the prism in this manner, the beam light can also be polarized, and noise can be reduced.

(f Example of use) [Figs. 3 to 5] Figs. 3 to 5 show the state in which the optical axis adjustment mechanism of the optical pickup device of the present invention is provided in the optical pickup device 14.

15 is a base substrate of the optical pickup device 14, and the base substrate 15 is formed of a sheet metal material.

Reference numeral 16 denotes an objective lens drive unit, which is disposed at a position closer to one end than the center of the base substrate 15, as will be described later. That is, the objective lens drive section 1
6 is a two-axis movable body provided with an objective lens 17 and supported so as to be movable in the optical axis direction of the objective lens 17 and in a direction orthogonal to the optical axis direction; A support substrate 18 is provided on a base substrate 15 and is equipped with a plurality of coils, magnets, etc. for controlling the position in the direction, and supports the objective lens drive section 6.
It is screwed to these supports 19, 19, . . . while being placed on the upper end surfaces of the columns 9, 19, .

Further, a part of the support substrate 18 of the objective lens driving section 16 is used as the upper wall 10 of the holder 5 of the optical axis adjustment mechanism of the optical pickup device of the present invention.

That is, the support substrate 18 of the objective lens drive unit 16 is provided with a reference hole 4 at a position corresponding to the objective lens 17, and the reference hole 4 is provided on the lower surface of the support substrate 18.
A cylindrical portion 11 is vertically provided so as to surround the cylindrical portion 11 .

Further, a window 12 is formed on the side of the cylindrical portion 11 facing a beam splitter, which will be described later, so as to receive the beam light, and furthermore, three windows are formed on the lower end surface of the cylindrical portion 11. The ends of the mirror support member holding plate springs 13, 13, 13 are fixed with screws. Then, the mirror support member 2 is housed in the cylindrical portion 11, and the spherical surface 8 of the mirror support member 2 is pressed against the periphery of the reference hole 4 by the plate springs 13, 13, 13, and the optical axis adjustment mechanism 1 of the optical pickup device is configured.

20 is a photodiode, and the photodiode 20 is connected to the anti-optical axis adjustment mechanism 1 of the base substrate 15.
The optical axis adjustment mechanism 1 is disposed at a side end portion facing the optical axis adjustment mechanism 1.

21 is a semiconductor laser, and the semiconductor laser 21 includes an optical axis adjustment mechanism 1 and a photodiode 20.
The base substrate 15 is disposed at an end portion of the base substrate 15 on a line substantially in the center of the two and orthogonal to a line connecting the two, so as to face the center portion.

22 is a beam splitter for reflecting the beam light emitted from the semiconductor laser 21 toward the optical axis adjustment mechanism 1 and transmitting the return light from the optical disk toward the photodiode 20. , the beam splitter 22 includes a semiconductor laser 21 and a photodiode 2.
0 and the optical axis adjustment mechanism 1 at an inclination angle of 45°.

Reference numeral 23 denotes a phase diffraction grating for dividing the beam emitted from the semiconductor laser 21 into a plurality of beams, including a main beam for recording and detection and servo, and a sub-beam exclusively for servo. is arranged on the base substrate 15 between the semiconductor laser 21 and the beam splitter 22.

24 is a cylindrical lens for irradiating the light receiving surface of the photodiode 20 with the return light from the recording surface of the optical disk at a predetermined spot;
The cylindrical lens 24 is arranged on the base substrate 15 between the photodiode 20 and the beam splitter 22.

The light beam emitted from the semiconductor laser 21 is divided into a plurality of light beams by the phase diffraction grating 23, and then reflected by the beam splitter 22 toward the optical axis adjustment mechanism 1. The light is reflected toward the objective lens 17 by the reflective surface 3a of the prism 3 of No. 1, and after being given condensing properties by the objective lens 17, the light is condensed onto the recording surface of the optical disk. The return light that is modulated on the recording surface of the disk and reflected toward the objective lens 17 passes through the objective lens 17 and then passes through the prism 3 of the optical axis adjustment mechanism 1.
The light is reflected toward the beam splitter 22 at the reflecting surface 3a, passes through the beam splitter 22, and enters the cylindrical lens 24, where the light is focused in a predetermined direction and then irradiated onto the photodiode 20. will be done.

If the optical axis of the objective lens 17 is not perpendicular to the optical disk, the returned light may be weak and cannot be detected, but by adjusting the optical axis adjustment mechanism 1 as described above, the return light may be The optical axis can be adjusted to be perpendicular to the optical disk.

(g Modification) [Figures 6 and 7] In the first embodiment of the optical axis adjustment mechanism of the optical pickup device of the present invention, the reflecting surface is formed by a 45° prism 3.
Although the surface 3a corresponds to the right angle, the present invention is not limited to this, and a flat mirror may be attached to a mirror support member as shown in FIG.

That is, in the modified example shown in FIG.
A second groove 26 shallower than the first groove 25 is formed on the side opposite to the side where groove 5 is formed so that the bottom surfaces of both grooves 25 and 26 are parallel to each other.
A window 27 is formed to penetrate through the bottom surfaces 25a and 26a of the first groove 25, and a reflective surface 28a is formed on the bottom surface 25a of the first groove 25 so that the reflective surface 28a faces the second groove 26 side of the window 27. A flat mirror 28 is attached to the top.

Further, the mirror support member 2 does not need to have a spherical surface in its entirety; only the portion (necessary for adjustment) that contacts the periphery of the reference hole 4 of the holder 5 may be made into a spherical surface 8 as shown in FIG. good.

(G Effect of the invention) As is clear from the above description, the optical axis adjustment mechanism of the optical pickup device of the invention includes a reflection mirror that bends the beam light emitted from the laser light source by approximately 45 degrees toward the objective lens. An optical axis adjustment mechanism for an optical pickup device comprising: a mirror support member having at least a spherical surface and a reflective surface of the reflective mirror disposed on a plane including a center of the spherical surface; It consists of a holder for holding, and a pressing means for pressing the mirror supporting member onto the holder, the holder has a reference hole formed in it with a diameter smaller than the spherical diameter of the mirror supporting member, and the mirror supporting member is pressed against the pressing member. It is characterized in that the spherical surface is pressed against a reference hole formed in the holder by a means.

Therefore, according to the present invention, since the optical axis of the beam light can be adjusted in all directions, the optical disk can be irradiated with the beam light at a correct angle. Moreover, this makes it possible to reduce the dimensions and mounting precision of each optical component in the optical pickup device, and to reduce the manufacturing cost of the optical pickup device.

[Brief explanation of the drawing]

1 and 2 show an example of the implementation of the optical axis adjustment mechanism of the optical pickup device of the present invention, in which FIG. 1 is a sectional view, FIG. 2 is a perspective view of the main parts, and The figures show an example of using the optical axis adjustment mechanism of the optical pickup device of the present invention in an optical pickup device. FIG. 3 is an overall perspective view, FIG. 4 is an exploded perspective view, and FIG. Exploded perspective views, FIGS. 6 and 7 show modified examples of the optical axis adjustment mechanism of the optical pickup device of the present invention, FIGS. 6 A and B show the first modified example, and FIG. A shows the main part. Figure B is a sectional view taken along the line B-B of Figure A, Figure 7 is a sectional view of the main part showing the second modification, and Figure 8 is a diagram for explaining the outline of the optical pickup device. Explanatory diagram, No. 9
The figure is a perspective view showing the main parts of a conventional optical axis adjustment mechanism in an optical pickup device. Explanation of symbols, 1... Optical axis adjustment mechanism, 2... Mirror support member, 3... Reflection mirror, 3a... Reflection surface, 4... Reference hole, 5... Holder, 6... Pressing means, 8... ... Spherical surface, 14 ... Optical pickup device, 28 ... Reflection mirror, 28a ... Reflection surface, O
...The center of the ball.

Claims (1)

[Claims for Utility Model Registration] An optical axis adjustment mechanism for an optical pickup device having a reflecting mirror that bends a beam emitted from a laser light source by approximately 45 degrees toward an objective lens, the mechanism having at least a spherical surface at least in part. , a mirror support member in which the reflective surface of the reflective mirror is arranged on a plane including the spherical center of the spherical surface, a holder for holding the mirror support member, and a pressing means for pressing the mirror support member against the holder, A reference hole having a smaller diameter than the spherical diameter of the mirror support member is formed in the holder, and the spherical surface of the mirror support member is pressed against the reference hole formed in the holder by the pressing means. Optical axis adjustment mechanism for optical pickup equipment.