JPH11232653A - Optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a yield by increasing an adjustment amount of an attitude adjustment mechanism for an objective lens of an optical pickup. SOLUTION: A spherical convex part 5a set at a lens mount stage 5 where an objective lens is mounted and a spherical concave part 4a of the same radius as the convex part 5a set at a base 4 are brought in touch with each other, so that the lens mount stage 5 can be freely inclined on the center of the spherical face. An attitude of the objective lens is adjusted by a clamp amount whereby two bolts 8 urged by a bolt 10 and a compression spring 11 clamp a female screw part 5c of the lens mount stage 5. In the thus-constituted attitude adjustment mechanism, a count of threads of the female screw part 5c is not larger than one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical pickup used in an optical disk device, and more particularly to an attitude adjusting mechanism of an objective lens for condensing a laser beam.

[0002]

2. Description of the Related Art FIG. 1 shows a configuration of a conventional optical pickup. A laser beam 1 emitted from a semiconductor laser (not shown) is converged on an optical disc 3 by an objective lens 2,
The reflected light of the laser light 1 is applied to a light receiving surface of a photodiode (not shown) to read a recording signal. The objective lens 2 is mounted on a lens mounting plate 5, and the lens mounting plate 5 is mounted between the base 4 and the objective lens 2.
The attitude adjusting mechanism 30 is configured so that the optical axis of the laser beam 1 and the optical axis of the laser beam 1 coincide with each other.

[0003] Further details will be described with reference to FIG. In the figure, the objective lens 2 and the focusing coil 24 are installed on the lens holder 25, and the tracking coil 23 is adhered to the focusing coil 24. The lens holder 25 is attached to the lens attachment plate 5 by the hinge 6 so that it can be slightly moved in the x-axis direction and the z-axis direction in the figure. The lens mounting plate 5 is provided with yokes 21a and 21b made of a magnetic material, and a magnetic field is formed by a magnet 22 bonded to the yoke 21a.
Is inserted into the focusing coil 24 and positioned to apply a magnetic field to the focusing coil 24 and the magnetic field effective portion 23 a of the tracking coil 23.

When a current flows through the focusing coil 24 through the flexible substrate 7, an electromagnetic force is generated by the Fleming's left hand rule, and the lens holder 25 is moved in the z direction to perform a focusing operation. When a current flows through the tracking coil 23 through the flexible substrate 7, the tracking operation is performed by moving the lens holder 25 in the x-axis direction by an electromagnetic force similarly generated by the current flowing through the magnetic field effective portion 23a.

The lens mounting plate 5 is provided with a through hole 5b through which laser light passes, and a spherical convex portion 5a projecting downward in the drawing is formed around the through hole 5b. The base 4 is provided with a through hole 4b through which the laser beam passes, and a spherical concave portion 4a having the same radius as the outer periphery of the convex portion 5a is formed around the through hole 4b.

The lens mounting plate 5 and the base 4 are arranged such that the convex portion 5a and the concave portion 4a are in contact with each other, and the lens mounting plate 5 and the base 4 can be inclined with respect to the center of the spherical surface. ing. A bolt 10 fixed through a compression spring 11 to a female screw portion 5d provided in the lens mount 5 through an insertion hole 4d provided in the base 4, and a lens mount through an insertion hole 4c provided in the base 4. The inclined posture of the lens mount 5 is determined by two bolts 8 fixed to the female screw portion 5c provided on the lens mount 5.

A method for adjusting the inclination of the lens mounting plate 5 and the base 4 will be described with reference to FIG. FIG. 3 is a cross-sectional view of the posture adjustment mechanism unit 30,
The lens mounting plate 5 is fixed at one place by a bolt 10 through an insertion hole 4d provided at the bottom, and abuts against the bottom surface of a counterbore 4e in which the compression spring 11 is inserted. It is energizing.

The bolt 8 on the opposite side of the fulcrum B from the compression spring 11 is urged upward in the drawing by the compression spring 11, so that the seat 8a is pressed against the seating surface 8a around the insertion hole 4c and passes through the insertion hole 4c. The screw is engaged with the female screw portion 5c of the lens mounting plate 5, and the inclination between the lens mounting plate 5 and the base 4 is adjusted by the amount of tightening, so that the optical axis of the objective lens 2 (see FIG. 2) and the laser beam are adjusted. The posture of the objective lens 2 is adjusted so that the optical axis of the objective lens 1 (see FIG. 1) coincides.

At this time, the bolts 8 are provided at two places because the posture adjustment requires, for example, a tilting mechanism in two directions of the tilt in the xz plane and the tilt in the yz plane in FIG. 2 described above. The fulcrum and the positions of the two bolts 8 are projected on the xy plane so as not to be on a straight line.

[0010]

However, FIG. 4 shows a state in which the inclination is adjusted by such a configuration, and the adjustable amount is limited by the contact between the inner wall 12 of the insertion hole 4c and the bolt 8. . This is the lens mounting plate 5
FIG. 5 shows the details of the female screw portion 5c of FIG. 5 in which the number of threads of (thickness of the lens mounting plate 5) / (thread pitch) meshes with the bolt 8 so that the bolt 8 is substantially perpendicular to the lens mounting plate 5. This is because it is held, and when a large adjustment amount is required, the adjustment becomes impossible and the yield is reduced.

To avoid this, it is conceivable to increase the diameter of the insertion hole 4c. However, since the maximum diameter of the insertion hole 4c is determined by the diameter of the head of the bolt 8, if the diameter of the insertion hole 4c is increased, the bolt 8 becomes larger. There was a problem that a commercial product could not be used and the cost was increased.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical pickup which can easily increase the amount of posture adjustment and improve the yield.

[0013]

To achieve the above object, the present invention provides an optical pickup in which a predetermined portion of a holding member for holding an objective lens is attached to a base via an adjusting bolt. The thickness of the female screw portion of the holding member that engages with the screw member is thinned so that the female screw portion does not partially have a thread root.

According to this structure, the holding member holding the objective lens is positioned by the bolt, and the inclination of the objective lens is adjusted by adjusting the amount of tightening of the bolt to adjust the attitude of the objective lens. At this time, the female screw part to be tightened with the bolt is formed thin so that there is no thread valley partially, the bolt is meshed with the female screw with one or less threads, the holding member is fixed, and between the bolt and the female screw part The resulting gap allows the holding member to be positioned even when the holding member and the bolt are not perpendicular.

Further, according to the present invention, the base and the holding member each have a through hole through which a laser beam passes, and a spherical projection provided around the through hole of the holding member; A portion provided in contact with the spherical shape or the convex portion provided around the through hole abuts the circular concave portion to form a fulcrum, and the center of the spherical surface of the convex portion coincides with the center of the objective lens. ing.

According to this configuration, the spherical convex portion provided around the through hole of the holding member provided with the through hole through which the laser beam passes, and the spherical or conical portion provided around the through hole of the base. The fulcrum is formed at the center of the objective lens by abutment with a concave portion such as a surface, and the holding member is positioned by the fulcrum and the bolt, and the inclination of the objective lens is adjusted by adjusting the amount of tightening of the bolt to adjust the posture of the objective lens. At this time, the direction can be changed without the parallel movement of the objective lens.

Further, according to the present invention, the thickness of the female screw portion is regulated by a spot facing. According to this configuration, the posture is adjusted by engaging the bolt with the female screw portion having one or less ridges, and the female screw portion is formed by a counterbore provided on the holding member to have a thickness such that there is no screw root.

According to the present invention, the spot facing is dish-shaped.
According to this configuration, the posture is adjusted by engaging the bolt with the female screw portion having one or less threads, and the female screw portion is formed to have a thickness of one screw or less by the countersunk bar provided on the holding member.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the same members as those in the conventional example are denoted by the same reference numerals. FIG. 6 is a sectional view showing details of the female screw portion 5c of the lens mounting plate 5 (holding member) of the embodiment of the present invention. According to the figure, a dish-shaped counterbore 5e is provided on one surface of the lens mounting plate 5, the thickness t of the female screw portion 5c is reduced, and the number of threads is one or less. FIG. 7 shows a state in which the posture adjustment mechanism 30 is configured using such a lens mounting plate 5 and the posture is adjusted.

According to the figure, even if the inclination of the lens mounting plate 5 becomes large, the bolt 8 does not come into contact with the inner wall 12 of the insertion hole 4c. This is because the female thread 4c has one or less thread and a gap is formed between the female thread 4c and the male thread of the bolt 8 so that the bolt 8
Can be held even if it is not perpendicular to the lens mounting plate 5. By being urged by the bolt 10 and the compression spring 11, almost the entire circumference of the bearing surface 8 a of the bolt 8 comes into contact with the base 4. This is because the bolt 8 is maintained perpendicular to the base 4.

A more detailed description will be given with reference to FIG.
FIG. 12 is a top view showing the details of the female screw portion 5c of the lens mounting plate 5, in which 26 indicates a thread root portion, and 27 indicates a vertex portion of the screw thread. Reference numeral 28 denotes an edge portion of the screw thread that does not reach the top of the front and back surfaces of the lens mounting plate 5. (a) shows a case where the thickness of the female screw portion 5c is one or more threads, and the apex 27 of the screw thread and the thread valley 26 are all around the female screw when viewed from above.

FIG. 3B shows a case where the thickness of the female screw portion 5c is a half screw thread, and the thread valley exists only between the areas G. Mountain Peak 2
There are seven. At this time, E shown by a diagonal line without the apex 27 of the thread
A gap is formed in the portion with respect to the inner diameter d1 (trough diameter of the bolt 8).

This gap is formed when the thickness of the female screw portion 5c is less than one thread, and becomes larger as the thickness becomes thinner. In the case where the thickness of the female screw portion 5c is one-fourth of the thread as shown in (c), the thread valley 26 exists only in the range H, and the thread is located in a range H ′ point-symmetric with the range H. There is a mountain peak 27. The portion F without the apex 27 of the thread is the inner diameter d.
1 (the root diameter of the bolt 8) and the gap is large.

Therefore, if the thickness of the female screw portion 5c is reduced to one thread or less so that a threadless portion is formed in the female screw portion, the gap between the female screw and the bolt 8 becomes large, and the posture adjustment amount is thereby increased. And the production yield of the optical pickup can be improved.

The lower limit of the thickness of the female screw portion 5c is determined in consideration of the height and reliability of the gap and the ridge so as to mesh with the bolt 8, but as shown in FIG. If the thickness is less than 5 threads, there is a possibility that the portion having the inner diameter d1 of the female screw is lost and it is not possible to maintain the engagement with the bolt 8, so that the thickness of 0.5 threads or more is desirable. The same effect can be obtained by forming the spot facing 5e into a cylindrical shape or a long hole shape as shown in FIG.

The fulcrum and the urging means may be formed by other methods. For example, as shown in FIG. 9, a spherical projection 4f and a recess 5f which comes into contact with the projection 4f are used to mount the base 4 and the lens. The fulcrum B is provided at the end of the mounting plate 5, and the base 4 and the lens of the bolt 8 are provided even if the tension spring 14 is installed at a position opposite to the fulcrum B with respect to any of the two bolts 8. The mounting plate 5 can be urged away from the mounting plate 5.

Further, as shown in FIG.
a and a concave portion 4a that comes into contact with the convex portion 5a are provided at the ends of the base 4 and the lens mounting plate 5 to form a fulcrum B.
Are located on the same side with respect to the fulcrum B.
Even if 5 is installed, the base 4 of the bolt 8 and the lens mounting plate 5 can be similarly urged away from each other.
Further, the adjustment may be performed with three bolts without providing the fulcrum and the urging means.

In the attitude adjusting mechanism 30 as shown in FIGS. 9 and 10, the optical axis of the objective lens 2 is adjusted to be parallel to the optical axis of the laser beam, and then the semiconductor laser and the objective lens 2 are moved (not shown). It is necessary to perform parallel translation by a mechanism to make both optical axes coincide, and the straightness at the time of parallel movement may cause the posture to go out of order. .

As shown in FIG.
b, a convex portion 5a and a concave portion 4a are provided around the periphery of 5b to form a fulcrum B so that the center of the objective lens 2 is set to coincide with the fulcrum B, and the objective lens 2 is installed. It is desirable to perform the rear posture adjustment because the center of the objective lens 2 does not move at the time of posture adjustment, so that the adjustment becomes easy and a moving mechanism is not required.

The position of one of the bolts 8 is designated as point A,
When the position of the other bolt 8 is set to the point C, the lens mounting plate 5 is tilted about the line BC (B is the fulcrum B) by adjustment of the point A,
Since the lens mounting plate 5 is tilted about the line AB by adjusting the point C, the line B ′ is obtained by projecting these two lines on a plane perpendicular to the laser beam.
If the C 'line A'B' is not at a position orthogonal to the line, the operation becomes complicated because one adjustment affects the other inclination direction. Therefore, the position of the bolt 8 is determined by the lines A'B 'and B'C'.
It is preferable to arrange them at positions orthogonal to each other because the work becomes easier.

The fulcrum B is formed by the contact between the spherical convex portion 5a and the spherical concave portion 4a.
Even if it is formed in a conical (FIG. 11 (a), (b)) or cylindrical (FIG. 11 (c)) concave portion as shown in FIG. A fulcrum can be configured. Further, the concave portion 4a may be formed in a plane so as to make a point contact, and in this case, the convex portion 5a may be formed in a conical shape. Alternatively, a concave member may be provided in the lens mounting plate 5 and the base 4 by providing a spherical member, and the fulcrum may be formed by another method.

The lens mounting plate 5 may be made of a plate material having a thickness of one thread or less. However, it is better to provide the spot facing 5e while maintaining the strength of the lens mounting plate 5 with one or less female threads. This is desirable because a portion can be formed. Although the insertion hole 4c is provided in the base 4 and the female screw portion 5c is provided in the lens mounting plate 5,
The same effect can be obtained by providing an insertion hole in the lens mounting plate 5 and providing the female screw portion in the base 4. Further, although the lens mounting plate 5 is formed of a thin plate and the base 4 is formed of a thick plate, the same effect can be obtained regardless of the thickness of each member by providing the counterbore. it can.

[0033]

According to the first aspect of the present invention, the amount of adjustment of the attitude of the objective lens can be increased with a simple configuration, and the production yield of the optical pickup can be improved.

According to the second aspect of the present invention, since the center of the objective lens does not move at the time of the posture adjustment, the posture adjustment work becomes easy and the number of steps can be reduced.

According to the third or fourth aspect of the present invention,
One or less female threads can be easily formed without lowering the strength of the member forming the female threads.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a conventional optical pickup.

FIG. 2 is a perspective view showing details of a configuration of a conventional optical pickup.

FIG. 3 is a plan view showing a posture adjustment mechanism of a conventional optical pickup.

FIG. 4 is a plan view showing a posture adjustment state in a posture adjustment mechanism of a conventional optical pickup.

FIG. 5 is a plan view showing a lens mounting plate of a conventional optical pickup.

FIG. 6 is a plan view showing a lens mounting plate of the optical pickup of the present invention.

FIG. 7 is a plan view showing a posture adjustment state in the posture adjustment mechanism of the optical pickup of the present invention.

FIG. 8 is a plan view showing another embodiment of the lens mounting plate of the optical pickup of the present invention.

FIG. 9 is a plan view showing another embodiment of the attitude adjustment mechanism of the optical pickup of the present invention.

FIG. 10 is a plan view showing another embodiment of the attitude adjustment mechanism of the optical pickup of the present invention.

FIG. 11 is a schematic view illustrating a method of configuring a fulcrum of the attitude adjustment mechanism of the optical pickup according to the present invention.

FIG. 12 is a schematic top view illustrating the shape of a female screw portion of the attitude adjustment mechanism of the optical pickup of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser beam 2 Objective lens 4 Base 4a Concave part 4c Insertion hole 5 Lens mounting plate 5a Convex part 5c Female screw part 5e Counterbore 8 Bolt 11, 15 Compression spring 14 Tension spring 30 Posture adjustment mechanism B Support point

Claims (4)

[Claims] 1. An optical pickup in which a predetermined portion of a holding member for holding an objective lens is attached to a base via an adjusting bolt, wherein a thickness of a female screw portion of the holding member which meshes with the adjusting bolt is adjusted to a thickness of the female screw portion. An optical pickup characterized in that it is thinned so that there is no thread valley partially. 2. The base and the holding member each have a through hole through which laser light passes, and a spherical projection provided around the through hole of the holding member; A portion provided in contact with the spherical shape or the convex portion provided around the hole makes contact with the circular concave portion to form a fulcrum, and the center of the spherical surface of the convex portion coincides with the center of the objective lens. The optical pickup according to claim 1, wherein: 3. The method according to claim 1, wherein a thickness of the female screw portion is regulated by a spot facing.
An optical pickup according to claim 1. 4. The optical pickup according to claim 3, wherein the spot facing is dish-shaped.