JPH11134656A - Optical head device and optical axis tilt adjusting jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent convergent beam characteristic and to perform high density recording/reproducing. SOLUTION: This device 1 is provided with a gonio-base positioning hole 9 opening in the optical axial direction of an optical path 6a for a reflection beam between a 45 deg. mirror 4 and an objective lens on an optical head base 5, and a spherical seat face 9a having a prescribed curvature is formed on the opening peripheral edge of this gonio-base positioning hole 9. Further, an optical axis tilt adjusting gonio-base 3 having a spherical surface 3a having the curvature suited to this spherical seat face 9a and a flat surface 3b placed on the reverse head base side of this spherical surface 3a is fitted, and the 45 deg. mirror 4 is fitted onto the flat surface 3b of this gonio-base 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device having a function of adjusting the inclination of an optical axis and an optical axis inclination adjusting jig.

[0002]

2. Description of the Related Art Generally, an optical disk device is provided with an optical head device having an optical path in which a light beam from a light source passes through a composite prism on an optical head base and then passes through an objective lens and reaches an optical disk. Are known.

Conventionally, as this kind of optical head device,
For example, the one shown in FIG. 3 is employed. The optical head device will be described with reference to the same drawing. In the same drawing, the optical head device denoted by reference numeral 51 is a laser (not shown), a high-frequency superimposing module 52, and a laser pen 53.
, Compound prism 54, objective lens 55, and half mirror 5
And each of these optical components is an optical head device main body 5.
7 is provided on an optical head base (not shown).

[0004] The high-frequency superimposing module 52 reduces laser noise, and the laser pen 53 has a collimator lens 58 therein and converts the laser light into parallel light (collimated light).

The composite prism 54 includes a wedge-shaped prism 59, a polarizing beam splitter 60, a 45 ° mirror 61 and a 1/4
And a wave plate 62. The wedge prism 59 and the polarizing beam splitter 60 transmit the collimated light from the laser pen 53, and the 45 ° mirror 61 deflects the transmitted collimated light. The quarter-wave plate 62 transmits the collimated light after polarization.

[0006] The objective lens 55 is a lens movable in two axial directions of a focus direction and a tracking direction, and is incorporated in a lens holder 63 for an actuator. Thereby, the collimated light is transmitted as circularly polarized light and focused on an optical disk (not shown).

[0007] The half mirror 56 transmits the beam light (beam reflected light from the optical disk) from the polarization beam splitter 60 as a beam light a and reflects it as a beam light b.

In the optical outward path of the optical head device thus configured, laser light from a laser (not shown) is converted into parallel light by a laser pen 53, and the parallel light is converted into a P wave by a wedge-shaped prism 59 and a polarization beam splitter. After being sequentially incident on 60, the light is deflected 90 ° by a 45 ° mirror 61 and
The light passes through the quarter-wave plate 62, enters the objective lens 55 as circularly polarized light, and is focused on an optical disk (not shown).

On the other hand, in the optical return path, the polarization axis is rotated by 90 ° with respect to the optical outward path, and the reflected light from the optical disk (not shown) passes through the quarter-wave plate 62 and is rotated by 45 °.
The light is polarized 90 ° by the mirror 61, and is polarized by the polarization beam splitter 60.
After being incident as an S-wave, is polarized 90 ° by the polarization beam splitter 60 and is transmitted through the half mirror 56.
The focus error (FE) signal and the tracking error (TE) signal are detected from the
An RF signal is detected from the light beam b reflected by 90 °.

In the composite prism of this type of optical head device, after the optical axis of the collimated light is reflected by a 45 ° mirror 61, as shown in FIG. Although they are designed to pass through the origins of the X axis m and the Y axis n, respectively,
The optical axis inclination of the inclination θT in the tangential direction of the optical disk and the inclination θR in the radial direction of the optical disk is generated from the error in the joining accuracy of each component and the dimensional accuracy.

FIGS. 5 (a) and 5 (b) are a plan view and a side view of FIG. 4, and a tilt occurs in the optical path (optical axis) due to the optical polarization accuracy of the 45 ° mirror 61 and the tilt of the prism at the beam incident portion. Indicates the status. In this case, the beam reflected by the 45 ° mirror 61 is polarized with an angular accuracy of ± 10 minutes.

The processing accuracy of the optical axis tilt in the wedge prism 59, the polarizing beam splitter 60 and the 45 ° mirror 61 as optical components of the compound prism 54 is ± 10 minutes (0.166 °), respectively. When components are combined and added in a direction that degrades accuracy, ±
20 minutes (0.33 °) or more.

In such a composite prism, each optical component is assembled by bonding from the state shown in FIG. 6, but if the bonding accuracy of the 45 ° mirror 61 is not sufficient, it will be as shown in FIG. In this case, assuming that the inclination angle of the 45 ° mirror 61 in the optical disk radial direction is θ, the inclination of the light beam reflected by the 45 ° mirror 61 in the optical disk radial direction is as large as 2θ.

[0014]

However, the conventional optical head device does not have a function of correcting the inclination of the optical axis, so that not only coma but also astigmatism has occurred. In particular, when the numerical aperture (= 0.6) of the objective lens 55 is large, the coma aberration with respect to the beam inclination (optical axis inclination) increases.

As a result, there has been a problem that good focused beam characteristics cannot be obtained and high-density recording / reproduction cannot be performed.

The present invention has been made in view of such circumstances, and an optical head device and an optical axis tilt adjusting jig capable of obtaining good focused beam characteristics and thereby performing high-density recording and reproduction. For the purpose of providing.

[0017]

According to a first aspect of the present invention, there is provided an optical head device, wherein a light beam from a light source passes through a composite prism on an optical head base, and a 45 ° mirror. And an optical path through which the reflected beam light passes through the objective lens and reaches the optical disk.
In the optical path, a gonio-table positioning hole that opens in the optical axis direction of the reflected beam optical path between the 45 ° mirror and the objective lens is provided in the optical head base, and a predetermined curvature is provided around the opening edge of the gonio-table positioning hole. A gonio table for adjusting the inclination of the optical axis having a spherical surface having a curvature conforming to the spherical seat surface and a deflected plane located on the side opposite to the head base side of the spherical surface is attached. The configuration is such that a 45 ° mirror is mounted on the deflected plane. Therefore, if the gonio table is moved relative to the ball seating surface before the gonio table is attached to the optical head base, the 45 ° mirror moves with this movement operation, and the tilt of the optical axis is adjusted.

According to a second aspect of the present invention, in the optical head device according to the first aspect, a plurality of notches for adhering a base are formed in a peripheral edge of the gonio table at predetermined intervals in a circumferential direction. is there. Therefore, the gonio table is attached to the optical head base in a plurality of notches.

The third aspect of the present invention is the first or second aspect.
In the optical head device described, the radius of curvature of the ball seating surface is
Set the distance from the light reflection point of the 45 ° mirror to the principal point on the optical axis of the objective lens plus the distance from the light reflection point of the 45 ° mirror to the deflected plane of the goniometer and the thickness of the goniometer. There is a configuration that has been. Therefore, the inclination of the optical axis is adjusted by moving the gonio table with respect to the spherical seat having a predetermined radius of curvature.

According to a fourth aspect of the present invention, in the optical head device according to the first, second or third aspect, a plurality of through-holes for adjusting the inclination of the optical axis are arranged in the peripheral edge of the gonio table at predetermined circumferential intervals. It is a configuration provided. Therefore, the inclination of the optical axis is adjusted using the plurality of through holes for adjusting the inclination of the optical axis.

According to a fifth aspect of the present invention, there is provided an optical axis tilt adjusting jig, which is provided on a base plate for light transmission facing a deflected plane of a gonio table via a 45 ° mirror, and protrudes from an adjustment target side of the base table. A structure comprising: a plurality of rods capable of abutting on an opening edge of each through hole according to claim 4; and a plurality of pins elastically held by these rods and capable of abutting the ball seating surface through the through holes. is there. Therefore, the inclination adjustment of the optical axis, the base table is opposed to the deflected plane of the gonio table via a 45 ° mirror, and each pin is inserted into each through hole to contact the ball seat surface,
And it is performed by bringing each rod into contact with the peripheral edge of the opening of each through hole.

According to a sixth aspect of the present invention, in the optical axis tilt adjusting jig according to the fifth aspect, an operation member for adjustment is projected from a central portion of the base base opposite to the rod projecting side.
Therefore, the tilt adjustment of the optical axis is performed by operating the operation member of the base.

The invention according to claim 7 is the invention according to claim 5 or 6.
In the optical axis inclination adjusting jig described above, a cutout for light transmission is formed in the base. Therefore, at the time of adjusting the inclination of the optical axis, the light beam passes through the notch for transmitting the light beam.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. FIGS. 1A and 1B are a plan view and a side view showing an optical head device according to a first embodiment of the present invention. In the following description, the same members as those in FIGS. Reference numerals are used, and detailed description is omitted. In the figure, the optical head device denoted by reference numeral 1 is
A laser (not shown), a high-frequency superimposing module 52, a laser pen 53, a compound prism 2, a quarter-wave plate 62, a gonio table 3, a 45 ° mirror 4, an objective lens 55, and a half mirror 56 are provided. Is the optical head body 5
7 is provided on the optical head base 5.

The composite prism 2 comprises a wedge-shaped prism 7 and a polarization beam splitter 8 which are arranged in parallel on the upstream and downstream sides of the optical path 6, respectively, and is mounted on the optical head base 5. The quarter-wave plate 62 is arranged below the objective lens 55 in FIG.

The optical head base 5 has four optical paths 6
A gonio stand positioning hole 9 is provided between the 5 ° mirror 4 and the objective lens (shown in FIG. 3), which opens in the optical axis direction of the reflected beam optical path 6a.

A ball seating surface 9a having a predetermined curvature is formed on the periphery of the opening of the gonio table positioning hole 9. Ball seat 9
The radius of curvature R of a is a distance from the light reflection point c of the 45 ° mirror 4 to the principal point d on the optical axis of the objective lens 55, and the deflected plane of the gonio table 3 from the light reflection point c of the 45 ° mirror 4 ( (To be described later) (１ ／ height of the 45 ° mirror 4) and the thickness of the gonio stand 3. Thereby, the inclination of the optical axis is adjusted by moving the gonio table 3 with respect to the ball seat surface 9a before the gonio table 3 is attached to the optical head base 5.

The gonio table 3 has a spherical surface 3a having a curvature adapted to the spherical seating surface 9a and a deflected plane 3b located on the side opposite to the head base with respect to the spherical surface 3a, and is mounted on the optical head base 5.

At the periphery of the gonio stand 3, four notches 3 for bonding the bases are arranged in parallel at a predetermined interval in the circumferential direction.
c and three notches 3c, three through-holes 3d for adjusting the tilt of the optical axis are provided between two notches 3c adjacent to each other.

Thus, the gonio table 3 is attached to the optical head base 5 by adjusting the angles (tilt of the optical axis) of the optical disk tangential direction θt and the optical disk radial direction θr by using the through holes 3d. This is performed by irradiating the ultraviolet adhesive used in the notch 3c with ultraviolet rays.

The 45 ° mirror 4 is provided on a plane 3 of the gonio table 3.
is mounted on b. Thus, when the gonio table 3 is moved with respect to the ball seat surface 9a before the gonio table 3 is attached to the optical head base 5, the 45 ° mirror 4 is moved with this moving operation, and the optical axis tilt is adjusted. .

In order to manually adjust the tilt of the optical axis of the optical head device thus configured (angle tilt accuracy ± 0.05 ° or less), the optical axis tilt adjusting optical device 11 shown in FIG. 1 is used. . That is, the manual adjustment of the optical axis inclination is performed by the half mirror 12 in which the light beams transmitted through the objective lens 55 of the optical head device 1 in the optical axis inclination adjusting optical device base B are arranged in parallel at predetermined intervals (1 m or more). 45 °
After being reflected by the mirror 13, these reflected light beams are transmitted by the half mirrors 14 and 15, and the CCD camera 16 and
17, and each of these image points is a CRT 18,
This is performed by moving the gonio table 3 so as to match the corrected origin on the XY plane displayed at 19.

At this time, when the gonio table 3 is moved and operated,
Angle adjustment in the biaxial direction of the 45 ° mirror 4 in the optical disk tangential direction (θt) and the optical disk radial direction (θr) is performed.

The automatic adjustment of the optical axis tilt is performed by reflecting the reflected beam light from the half mirror 12 and the 45 ° mirror 13 by the half mirrors 14 and 15 and then dividing each of these reflected mirror lights into a quadrant sensor and a two-dimensional sensor. This can be achieved by detecting by the position detecting sensors 20 and 21 such as optical position sensors, calculating the inclination of the optical axis from these detected beams by the arithmetic processing units 22 and 23, and outputting the calculated inclination to the CPU data bus 24.

Next, an optical axis tilt adjusting jig used for adjusting the optical axis tilt of the optical head device according to the first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a perspective view for explaining manual adjustment of the gonio table using an optical axis tilt adjusting jig used for adjusting the optical axis tilt of the optical head device according to the first embodiment of the present invention. The same members as those in (a) and (b) are denoted by the same reference numerals, and detailed description is omitted. In the figure, the optical axis tilt adjusting jig denoted by reference numeral 31 includes a base 32, a rod 33, a pin 34, and an operator 35.

The base 32 has a notch 32a through which the light beam from the 45 ° mirror 4 passes, and the entire surface of the base 32 is opposed to the plane 3b of the goniometer 3 via the 45 ° mirror 4. Is formed by

The rod 33 is composed of three cylindrical bodies which can abut on the periphery of the opening of each through hole 3d in the gonio table 3.
It is attached to the peripheral edge of the base table 32 on the side to be adjusted (gonio table). The pins 34 are made of three pins that can be inserted into the through holes 3d and contact the ball seating surface 9a. The pins 34 are elastically held in the rods 33 by exposing the tip of the pins to the outside.

The operator 35 is provided at the center of the base 32 on the side opposite to the rod projecting side. Thus, the adjustment of the tilt of the optical axis is performed by moving the operation element 35.

The manual adjustment of the gonio table by the optical axis tilt adjusting jig configured as described above is performed in advance by using the gonio table positioning hole 9.
Of the gonio table 3 placed on the optical head base 5 so that the spherical surface 3a is in contact with the spherical seat surface 9a of the
The base 32 of the optical axis tilt adjusting jig 31 is opposed via the mirror 4, the pins 34 are inserted into the through holes 3d to make contact with the ball seat surface 9a, and the rods 33 are inserted into the respective through holes. This is performed by contacting the periphery of the 3d opening.

At this time, the image points obtained by the CCD cameras 16 and 17 of the optical axis tilt adjusting optical device 11 shown in FIG. 1 are the origins on the calibrated XY plane displayed on the CRTs 18 and 19. So that the operator 3
5 is rotated by .theta.X, .theta.Y, .theta.Z around the X, Y, and Z axes of the rectangular coordinates.

In this embodiment, the base 32
Although the case where the notch 32a for light transmission is formed is described above, the present invention is not limited to this, and the same effect as that of the embodiment can be obtained even if a through hole (not shown) for light transmission is provided.

The radius of curvature of the goniometer in the present invention is, of course, not particularly limited to the above-described embodiment.

[0043]

As described above, according to the present invention, 4
A gonio-table positioning hole that opens in the optical axis direction of the reflected beam optical path between the 5 ° mirror and the objective lens is provided in the optical head base, and a spherical seating surface having a predetermined curvature is provided around the opening edge of the gonio-table positioning hole. Is formed, and a gonio table for adjusting the tilt of the optical axis having a spherical surface having a curvature conforming to the spherical seat surface and a deflected surface located on the side opposite to the head base of the spherical surface is attached, and on the deflected surface of the gonio table. Is 4
Since the 5 ° mirror is attached, if the goniometer is moved relative to the ball seat before attaching the goniometer to the optical head base, the 45 ° mirror moves with this movement, and the tilt of the optical axis is reduced. Adjusted.

Therefore, the inclination of the optical axis can be corrected before the gonio table is attached to the optical head base, so that the occurrence of coma and astigmatism can be prevented, and a good focused beam characteristic can be obtained. Density recording and reproduction can be performed.

[Brief description of the drawings]

FIGS. 1A and 1B are a plan view and a side view showing an optical head device according to a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining manual adjustment of a gonio table using an optical axis tilt adjusting jig used for optical axis tilt adjustment of the optical head device according to the first embodiment of the present invention.

FIG. 3 is a perspective view showing the appearance of a conventional optical head device.

FIG. 4 is a perspective view for explaining the optical axis inclination of a compound prism of a conventional optical head device.

5A and 5B are a plan view and a side view for explaining the optical axis tilt of the composite prism.

FIG. 6 is an exploded perspective view of the composite prism.

FIG. 7 is a perspective view showing an example of an assembly failure of the composite prism.

[Explanation of symbols]

 Reference Signs List 1 optical head device 2 compound prism 3 gonio table 3a spherical surface 3b deflected plane 3c cutout 3d through hole 4 45 ° mirror 5 optical head base 6 optical path 6a reflected beam optical path 7 wedge-shaped prism 8 polarizing beam splitter 9 gonio table positioning hole 9a ball seat Surface 31 Optical axis tilt adjustment jig 32 Base 32a Notch 33 Rod 34 Pin 35 Operator

Claims (7)

[Claims] 1. An optical path for transmitting a light beam from a light source through a composite prism on an optical head base, reflecting the reflected light beam on a 45 ° mirror, and transmitting the reflected light beam through an objective lens to an optical disk. A gonio-table positioning hole that opens in the optical axis direction of the reflected beam optical path between the 45 ° mirror and the objective lens in the optical path is provided in the optical head base. A goniometer for adjusting the tilt of the optical axis is formed, which has a spherical seat surface having a curvature, and has a spherical surface conforming to the spherical seat surface and a deflected surface located on the side opposite to the head base of the spherical surface. An optical head device, wherein the 45 ° mirror is mounted on a plane. 2. The optical head device according to claim 1, wherein a plurality of notches for bonding the bases are formed in the peripheral edge of the gonio table at predetermined intervals in the circumferential direction. 3. The gonio table according to claim 1, wherein a radius of curvature of the spherical bearing surface is a distance from a light reflection point of the 45 ° mirror to a principal point on an optical axis of the objective lens. The optical head device according to claim 1, wherein the dimension is set to a value obtained by adding a distance to the deflected plane and a thickness of the gonio table. 4. The optical head device according to claim 1, wherein a plurality of through-holes for adjusting the inclination of the optical axis are arranged in the peripheral edge of the gonio table at predetermined intervals in the circumferential direction. . 5. The base according to claim 4, wherein the base for light transmission is opposed to the deflected plane of the gonio stand via the 45 ° mirror, and the through-hole protrudes from the base to be adjusted. A plurality of rods which can be brought into contact with the peripheral edge of the opening, and a plurality of pins which are elastically held by these rods and which can pass through the respective through holes and come into contact with the ball seating surface. Shaft adjustment jig. 6. The optical axis tilt adjusting jig according to claim 5, wherein an adjusting operation member is projected from a central portion of the base base opposite to the rod protruding side. 7. The optical axis tilt adjusting jig according to claim 5, wherein a cutout for transmitting a light beam is formed in the base.