JPH0722737Y2 - Optical head optical sensor mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an optical sensor mounting structure of an optical head,
In particular, it relates to a means for adjusting the optical sensor mounting position.

[Prior Art] FIG. 4 shows an optical system configuration of a general optical head having a conventional optical sensor mounting structure. In the figure, a light beam emitted from a laser diode 1 is diffracted by a diffraction grating 2 and divided into three light beams (not shown in the figure), which are reflected at a right angle by a half mirror 3 and collimator lens 4 To form parallel light rays, which are converged by the objective lens 5 to form a light spot on the signal surface of the optical disk 6. The reflected light reflected by the optical disc 6 is the objective lens 5,
Pass the collimator lens 4 through the same path, and then the half mirror 3
Through the concave lens 7 to focus on the optical sensor 8.

By the way, generally, when assembling the optical head, the positional accuracy of the optical sensor 8 is required to be extremely high, and the optical axis direction of the light beam incident on the optical sensor 8 (this optical axis direction is defined as z-axis direction and is orthogonal to the z-axis). Two directions at right angles are x-axis direction and y
The optical sensor position adjustment in the axial direction (this adjustment is called the z-axis adjustment) requires a high adjustment accuracy of ± 10 μm or less, and the xy direction orthogonal to the z-axis direction (that is, the x-axis direction and the y-axis direction). Adjust the optical sensor position in the axial direction.
Adjustment of direction or xy adjustment) requires high adjustment accuracy of ± 3 μm or less.

In the conventional optical sensor mounting structure, the mounting plate with the optical sensor is simply fixed to the opt base with screws.For the xy adjustment of the optical sensor, the mounting plate is finely adjusted in the xy direction using an external jig. It was done by moving. For the adjustment of the optical sensor in the z-axis direction, a method is adopted in which the position of the concave lens 7 in the z-axis direction is moved and adjusted so that the return light focuses on the optical sensor 8.

[Problems to be Solved by the Invention] As described above, in the configuration in which two xy-direction adjustment points and z-axis direction adjustment points are separately provided, the position adjustment work of the optical sensor is complicated, and the concave lens is used. Since the number of required parts increases, the cost increases. Furthermore, since an external jig for adjusting in the xy direction is required, the adjusting device becomes expensive.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and it simplifies the configuration for adjusting the position of the optical sensor, does not require a concave lens, and does not require an external jig for adjustment. The purpose is to obtain a sensor mounting structure.

[Means for Solving the Problems] The present invention for solving the above problems is for z-axis adjustment that is cantilevered on an opt base so as to be elastically displaceable in the z-axis direction that coincides with the optical axis incident on the optical sensor. Leaf spring type mounting plate,
A z-axis direction adjusting means for adjusting the displacement of the z-axis adjusting leaf spring type mounting plate in the z-axis direction, and an xy adjusting mounting plate to which an optical sensor is attached and which is attached to the z-axis adjusting leaf spring type attaching plate. The xy adjustment mounting plate is provided in each of two orthogonal directions passing through the center of the optical sensor, and the z-axis direction adjusting plate is provided by a mounting screw serving as a rotation center axis when adjusting the optical sensor xy direction. An optical sensor mounting structure for an optical head, which is mounted on a spring-type mounting plate, and is provided with two rotating means for finely adjusting and rotating the mounting plate for xy adjustment around the mounting screws.

[Operation] In the above configuration, the position adjustment of the optical sensor in the z-axis direction is performed by
The z-axis adjusting means elastically displaces the z-axis adjusting plate spring type mounting plate in the z-axis direction.

For adjustment of the optical sensor in the xy direction, the xy adjustment mounting plate is first finely rotated about one mounting screw of two mounting screws in two orthogonal directions, for example, the position in the x direction. Adjustment is performed, and then fine adjustment rotation is performed around the other mounting screw to perform position adjustment in the y direction.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows the optical sensor mounting structure in the optical head, and also schematically shows another optical system of the optical head. Further, FIG. 2 is a front view of the optical sensor mounting structure, and FIG. 3 is an exploded perspective view of the same. In these figures, 10 is a part of the opt base and has a hole 10a through which the light beam passes. This opt base 10 forms a plane orthogonal to the z axis which is the optical axis of the light beam incident on the optical sensor 11, and the opt base 10 has a z-axis direction adjusting leaf spring type mounting plate 12 in the hole 12a. It is fixed in a cantilever shape with the threaded screw 13, and a hole 12b is made at the free end of the leaf spring type attachment plate (hereinafter referred to as leaf spring type attachment plate) 12 for adjusting the z-axis direction, and inserted into this hole 12b. Z-axis adjusting screw 14 is opt-base 1
It is screwed into the screw hole 10b provided in 0. This plate spring type mounting plate 12 is provided with a hole 12h through which a light beam passes, and the optical sensor 1
An xy adjustment mounting plate 15 having 1 at the center is attached. This xy adjustment mounting plate 15 has holes drilled in three places.
Mounting screws 16, 17, and 18 inserted from 15a, 15b, and 15c are screwed and fixed in screw holes 12c, 12d, and 12e formed in corresponding portions of the plate spring type mounting plate 12.

Holes 15a and 15b for inserting the two mounting screws 16 and 17
Are located in diagonal directions of the rectangular xy adjustment mounting plate 15, that is, in two orthogonal directions passing through the center of the optical sensor 11. Further, diagonally opposite corners of the holes 15a, 15b are formed with diagonal grooves 15d, 15e into which the shaft portion 19b of the eccentric pin 19 for performing xy adjustment of the optical sensor 11 is fitted. There is. In addition, the leaf spring type mounting plate 12 has a tip pin portion 19 of the eccentric pin 19.
Pin holes 12f and 12g for inserting a are formed on the diagonal lines. Then, in the optical sensor 11, a central four-divided photodiode 11a and left and right two-divided photodiodes 11b, 11b are arranged side by side in a diagonal direction.

The arrangement of the above optical sensor mounting structure in the optical disk device will be described. In FIG. 1, reference numeral O is the center of the optical disk, one-dot chain line (a) is the moving direction of the optical head, and one-dot chain arc (b) is the optical disk tangent line. The direction (signal track direction of the optical disk) is shown. Further, 20 is a laser diode, 21 is a diffraction grating, 23 is a half mirror, 24 is a collimator lens, 25 is a 45 ° mirror, and 26 is an objective lens. The objective lens 26 is above the 45 ° mirror 25 (on the front side in the direction orthogonal to the paper surface). In this embodiment, as shown in the figure, the optical axis of the light beam incident on the optical sensor 11 (that is, the z-axis) is set to a direction that forms an angle of 45 ° with the disc tangential direction. That is, the light beam emission direction of the laser diode 20 and each optical system are arranged so as to form an angle of 45 ° with respect to the optical head feeding direction (a).

Next, the operation will be described.

The laser light emitted from the laser diode 20 in the horizontal direction is divided into three light beams (not shown in the figure) by the diffraction grating 21, reflected by the half mirror 23 at the same horizontal angle, and passed through the collimator lens 24. Parallel light is reflected by the 45 ° mirror 25 in the vertical direction (that is, in the direction orthogonal to the disk surface), passes through the objective lens 26, and forms a light spot on the signal surface of the optical disk. The reflected light (that is, the return light) reflected by the disk surface passes through the objective lens 26 and 45
The light is reflected in the horizontal direction by the mirror, passes through the collimator lens 24, passes through the half mirror 23, and is focused on the optical sensor 11.

The optical sensor 11 is an optical sensor for returning light from the disc surface.
Although it is necessary to adjust the position in the z-axis direction so as to focus on 11, the z-axis adjustment is performed by turning the z-axis adjusting screw 14 to move the leaf spring type mounting plate 12 forward, that is, in the illustrated example. The position of the optical sensor 11 in the z-axis direction is adjusted by moving it to the opt base side or moving it to the rear side.

Further, adjustment in the xy direction orthogonal to the z axis is performed as follows. First, for adjustment in the x direction, the shaft portion 19b of the eccentric pin 19 is inserted into one groove 15e of the xy adjustment mounting plate 15, and the tip pin portion 19a at the tip of the eccentric pin 19 is inserted into the hole 12g. The optical sensor 11 is finely adjusted in the x direction by rotating the eccentric pin 19 around the tip pin portion 19a and finely rotating the xy adjustment attachment plate 15 around the attachment screw 17 by the shaft portion 19b. For adjustment in the y direction, similarly, the shaft portion 19b of the eccentric pin 19 is fitted into the other diagonal groove 15d, the tip pin portion 19a is inserted into the hole 12f, and the eccentric pin 19 is rotated. When the xy adjustment mounting plate 15 is finely adjusted and rotated about the mounting screw 16, the optical sensor 11 is finely adjusted in the y direction.

It should be noted that the movement of the optical sensor 11 at the time of the adjustment in the x direction and the adjustment in the y direction described above is not a linear movement but an arcuate movement, but since the movement amount is extremely small, there is no particular problem.

In the above embodiment, each optical system is arranged so that the optical axis direction of the light beam incident on the optical sensor 11 forms a 45 ° direction with the disc tangential direction because the xy adjustment mounting plate 15 is a diagonal line in two orthogonal directions. This is to prevent the height of the xy adjustment mounting plate 15 from increasing due to the structure in which the mounting screw 16 or 17 in the direction is rotated as the center. Such a structure is suitable for thinning the optical head. Therefore, it is not always necessary to set the optical axis direction to be the direction that makes an angle of 45 ° with the disc tangential direction. In this case, and when the 3-beam method is adopted as the tracking error detection method, the array of the 6-divided photodiodes 11a and 11b of the optical sensor 11 is in the horizontal direction. The mounting screw which also serves as the rotation center axis is provided at a position on the x'axis and y'axis in FIG. Needless to say, the tracking error detection method is limited to the three-beam method.

[Effects of the Invention] Since the present invention is configured as described above, it has the following effects.

Since the position adjustment of the optical sensor in the z-axis direction is performed only by adjusting the elastic displacement amount of the plate spring type mounting plate, the conventionally required concave lens is not required, and the number of parts is reduced. The structure is simplified and the cost is reduced.

In addition, in the prior art, adjustment at two locations in the xy direction and the z-axis direction was required, but in the present invention, adjustment is only required for the sensor mounting portion, so the adjustment work is significantly facilitated.

Also, the position adjustment work of the optical sensor in the xy direction is a simple task of finely adjusting and rotating the mounting plate for xy adjustment about the mounting screws arranged in two orthogonal directions.
The adjustment work is significantly facilitated, and no external adjustment system is required for this adjustment work, thus reducing the cost of the adjusting device.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an optical sensor mounting structure according to an embodiment of the present invention and another optical system of an optical head, and FIG. 2 is a front view of the same optical sensor mounting structure.
FIG. 3 is an exploded perspective view of the same, and FIG. 4 is an optical system configuration diagram of an optical head adopting a conventional optical sensor mounting structure. 10 …… Opto base, 11 …… Optical sensor, 12 …… Z-axis direction adjustment leaf spring type mounting plate (plate type mounting plate), 12b …… Hole, 1
4 …… Z-axis direction adjusting screw (z-axis direction adjusting means), 15…
… XY adjustment mounting plate, 16,17 …… Mounting screw that also serves as the rotation center axis, 15d, 15e… groove, 19 …… Eccentric pin (rotating means).

Claims (2)

[Scope of utility model registration request] 1. A leaf spring type mounting plate for z-axis adjustment, which is attached to an optical base in a cantilever manner so as to be elastically displaceable in the z-axis direction coincident with an optical axis incident on an optical sensor, and the z-axis adjusting plate. A z-axis direction adjusting means for adjusting the displacement of the spring-type mounting plate in the z-axis direction; and an xy-adjusting mounting plate that is mounted on the z-axis adjusting plate spring-type mounting plate together with the optical sensor. The mounting plate for use is mounted on the leaf spring type mounting plate for adjusting the z-axis direction with a mounting screw that is provided in each of two orthogonal directions passing through the center of the optical sensor and serves as a rotation center axis when adjusting the optical sensor xy direction. The xy adjusting mounting plate is provided with two rotating means for finely adjusting and rotating the mounting screws respectively around the mounting screws, and the z-axis direction adjusting means is provided in the two orthogonal directions of the xy adjusting mounting plate. Mounting screw The z-axis adjusting leaf spring type mounting plate has grooves formed on opposite sides to engage the shaft portions of the xy adjusting eccentric pin, and the tip pin portion of the xy adjusting eccentric pin is attached to the z-axis adjusting leaf spring mounting plate. An optical sensor mounting structure for an optical head, characterized by being provided with a pin hole for insertion. 2. The z-axis adjusting means is constituted by screwing a z-axis adjusting screw in the z-axis direction, which engages with a free end of a z-axis adjusting leaf spring type mounting plate, to an opt base. An optical sensor mounting structure for an optical head according to claim 1, wherein: