JPH08161756A - Objective lens positioning mechanism of optical disk device - Google Patents

Abstract

PURPOSE: To obtain a mechanism for positioning the objective lens of an optical disk device for improving the positioning accuracy of the objective lens for an optical body and at the same time increasing the margin for an inclination adjustment angle. CONSTITUTION: A protruding part 20 in spherical surface shape or conical shape is provided at either an optical body 1 or an actuator stand 4 and at the same time the protruding part 20 is engaged to a circular recessed part or a hole 22 provided at the other so that the actuator stand 4 can be inclined freely in all directions for the optical body 1. A pin part 21 is provided at either the optical body 1 or the actuator stand 4 and a pin part 21 is engaged to a slot 23 provided at the other. At least either of two pin parts or at least either of a round hole and a slot is formed in taper shape in a structure for positioning the optical body and the actuator stand with two pin parts and the round and long holes engaged to these pin parts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head used in an optical disk (including a magneto-optical disk) apparatus, and an actuator for adjusting a position of an objective lens in a focusing range and a tracking direction in a minute range with respect to an optical body. The present invention relates to a mechanism for positioning and adjusting the inclination of an actuator with respect to an optical body.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a conventional optical head, 1 is an optical body which is moved and positioned in the tracking direction of an optical disk (not shown), 2 is an objective lens, and 3 is an objective lens. 2 is an actuator for adjusting the position by moving 2 in the tracking direction and the focusing direction in a minute range. The actuator 3 is supported by an actuator base 4 attached to the optical body 1 and an elastic wire 5 that also serves as a current-carrying wire for the actuator base 4.
The lens holder 6 holds the objective lens 2 and a driving force generator 7 for moving the lens holder 6 in the tracking direction and the focusing direction by an electromagnetic force. The driving force generator 7 is attached to the lens holder 6. Focusing coil 7b and tracking coil 7 mounted
c, a yoke 4a fixed to the actuator base 4, a magnet 7a fixed to the yoke 4a, and the like. Reference numeral 8 is a mirror interposed between the objective lens 2 and a light beam generator or reader (not shown) mounted on the optical body 1.

Optical body 1 in such an optical head
The conventional positioning mechanism of the actuator base 4 with respect to
Two round pins 9 and 10 are provided at intervals in the optical body 1, and a round hole 11 and an elongated hole 12 are provided in the actuator base 4 so as to correspond to these pins 9 and 10, and these are mutually connected. Positioned by fitting. Here, one of the holes 12 is an elongated hole because the pins 9 and 10 and the hole 1 are
This is because an error in manufacturing position with respect to 1 and 12 is absorbed.

On the other hand, since it is necessary to set the optical axis of the objective lens 2 to be perpendicular to the optical disk, through holes 13 are provided at three positions of the optical body 1, and the actuator base 4 has three corresponding holes. Screw holes 14 are provided, a compression spring 15 is interposed between these holes 13 and 14, and the adjusting screw 16 is passed through the hole 13 and the compression spring 15 to make the screw hole 1
It is possible to adjust the inclination angle of the actuator base 4 with respect to the optical body 1 in an arbitrary direction by screwing into the optical axis 4 and changing the screwing depth, whereby the direction of the optical axis of the objective lens 2 supported by the actuator base 4 is changed. I am able to adjust it.

As described above, in order to make the tilt angle of the actuator base 4 adjustable, conventionally, as shown in the schematic plan view of FIG. 3 (A), two pins 9, 1 are provided on the optical body 1.
0 and the short diameter forming surface of the round hole 11 or the long hole 12 have a gap Δ.
e (for the sake of explanation, this Δe is exaggeratedly drawn).

Japanese Patent Publication No. 5-18181 discloses that
In order to solve the problem that it is difficult to make the long hole 12 with high dimensional accuracy, a round hole is provided instead of the long hole 12, and the cross-sectional shape of the pin 10 to be inserted into the round hole is changed to an oval or a rhombus. A structure that exhibits an equivalent manufacturing error absorbing function is disclosed.

[0007]

In such a conventional positioning mechanism for an optical head, the optical body 1 is centered around the X-axis direction in the plan view of FIG. 2A, that is, the major axis direction of the slot 12. When the actuator base 4 is tilted, the following formula (1) determined by the gap Δe and the thickness t of the actuator base 4 (see FIG. 2B which is a cross-sectional view taken along the line EE of FIG. 2A). Inclination (maximum inclination angle θ) can be achieved within the range of. θ = tan ⁻¹ (Δe / t) (1) Further, the inclination about the Y axis perpendicular to the X axis is
Since the gap between the both ends of the elongated hole 12 in the major axis direction and the pin 10 is large, the angle is the same as the tiltable angle about the X-axis center.

However, when the U line inclined with respect to the X and Y lines is inclined at the center, as shown in FIG. 2B, the circle having the diameters c of the pins 9 and 10 has a diameter d.
Acting to inscribe in a circular hole having
Of the holes 11 and 12 hit the edges a and b, respectively, and a large inclination angle θ cannot be obtained. That is, in this case, the tilt angle can be expressed as shown in the equation (2). θ = cos ⁻¹ {c / (d ² + t ² ) ^1/2 } −cos ⁻¹ {d / (d ² + t ² ) ^1/2 } (2) where L is between the centers of the pins 9 and 10. Where r is the radius of the pins 9 and 10 and α is the angle formed by the lines U and X, c
= Lcos α + 2r, d = c + f (α) · Δe (however, f
(Α) is a function of the angle α between the lines X and U). here,
In order to increase the positioning stability, the distance L between the pins 9 and 10 is increased, and in order to improve the accuracy, the gap Δe
When is smaller, the tiltable angle θ becomes smaller, and as a result, there is a problem in that the tilt adjustment range in an arbitrary direction cannot be widened and the target tilt angle θ cannot be obtained.

Further, if the Δe is increased in order to widen the adjustment range of the tilt of the objective lens, there is a problem that the positioning accuracy of the objective lens deteriorates. Tokoku 5
The problem disclosed in Japanese Patent No. 18181 has the same problem.

In view of the above-mentioned problems, the present invention provides an objective lens positioning mechanism for an optical disk device, which can improve the positioning accuracy of the objective lens with respect to the optical body and can increase the margin of the tilt adjustment angle. With the goal.

[0011]

In order to achieve the above object, the first invention of the present application positions the actuator of the objective lens with respect to the optical body of the optical head and adjusts the inclination of the actuator with respect to the optical body. In the mechanism, a spherical or conical convex portion is provided on either one of the optical body or the actuator base, and the convex portion is fitted into a circular concave portion or a hole provided on the other to form the fitting portion. The actuator base can be tilted in all directions with respect to the optical body as a center, and a pin portion is provided on either one of the optical body or the actuator base, and the pin portion is fitted into an elongated hole provided on the other side to form the convex portion. The distance between the portion and the center of the objective lens is shorter than the distance between the convex portion and the pin portion.

According to a second aspect of the present invention, a pin portion is provided on either one of the optical body or the actuator base, and the pin portion is fitted into a circular hole provided on the other side of the optical body or actuator base. Another pin portion is provided on one of the bases, the other pin portion is fitted into the elongated hole provided on the other, and at least one of the hole or the elongated hole corresponding to each pin portion is formed in a tapered shape. It is characterized by having done. Further, instead of forming these holes or elongated holes in a tapered shape, both pins may be formed in a tapered shape.

[0013]

In the first invention of the present application, a spherical or conical projection is provided on either one of the optical body or the actuator, and the projection is fitted into a circular recess or hole provided on the other, Since the pin portion and the long hole are fitted at different places, the fitting position of the convex portion and the concave portion or the hole is substantially unchanged, and the position changes because the fitting of the long hole and the pin portion is changed. Since only the joint portion is provided, the positioning accuracy is higher than in the case where the actuator base is displaced due to the gap between the pin of the hole at each of the two pins as in the conventional case. In addition, the fitting portion of the convex portion and the concave portion or hole,
The rotation range of the actuator base is wide, and the inclination is restricted in all directions only in the gap between the elongated hole and the pin portion, and the restriction of the inclination adjustment is relaxed, so that the inclination has a margin.

Further, in the second aspect of the present invention, the pin, the round hole or the elongated hole is tapered, so that the limitation of the inclination due to the contact between the edge of the hole and the pin when the actuator base is inclined is relaxed. As a result, the range in which the tilt can be adjusted is widened, the gap between the pin and the hole can be reduced by that much, and the positioning accuracy of the actuator base is also improved.

[0015]

1 (A) is an exploded perspective view showing an embodiment of a positioning mechanism for an objective lens with respect to an optical body according to the present invention, and FIG. 1 (B) is a longitudinal sectional view thereof. In FIG. 1, the same reference numerals as those in FIG. 6 are provided for exhibiting equivalent functions. Reference numeral 20 denotes a spherical convex portion integrally formed on the optical body 1 made of a metal casting, and 21 denotes the convex portion 2.
It is a round pin portion that is provided separately from 0 on the optical body 1 by integral molding.

Reference numeral 4a denotes a projection provided by projecting from one corner of the actuator base 4 to a position close to the objective lens 2, and the projection 4a has a cone rotatably fitted to the projection 20. -Shaped circular holes 22 are formed. Further, an elongated hole 23 into which the pin portion 21 is fitted is provided near the outer periphery of the actuator base 4 on the opposite side of the circular hole 22.

Reference numeral 16 denotes an adjusting screw for adjusting and fixing the inclination angle of the actuator base 4 with respect to the optical body 1,
The adjusting screws 16 are inserted through the through holes 13 provided at two positions of the optical body 1 and screwed into the screw holes 14 provided in the actuator base 4. Alternatively, the adjusting screw 16 may be inserted into a through hole provided in the actuator base 4 and screwed into a screw hole provided in the optical body 1. 15
Is a compression spring, and the compression spring 15 is interposed between the optical body 1 and the actuator base 4 so as to be located on the side opposite to the convex portion 20 with respect to the line connecting the two adjusting screws 16. Let In this way, the convex portion 20 and the compression spring 15 are arranged on opposite sides of the line connecting the two adjusting screws 16, so that the circular hole 22 is formed in the convex portion 20 by the force of the compression spring 15. Are pressed against each other, and the circular hole 22 side of the actuator base 4 is positioned. Reference numeral 4b denotes a pair of yokes formed integrally with the actuator base 4, and the yoke 4b
Penetrates through the opening of the lens holder 6 with a gap, and the magnets 7a are adhered to the opposing surfaces of the yokes 4b,
By energizing the tracking coil 7b and the focusing coil 7c mounted on the lens holder 6, the lens holder 6 is arranged to move in the tracking direction and the focusing direction.

This device is shown in FIGS. 1 (B) and 2 (C).
2D, which is a plan view of FIG. 2 and its FF cross-sectional view, the actuator 3 is attached to the optical body 1 by attaching the circular hole 22 of the actuator base 4 to the convex portion 20 provided on the optical body 1. While fitting, the oblong hole 23 is fitted to the pin portion 21, and the adjusting screw 16 is inserted into the through hole 13 with the compression spring 15 interposed between the optical body 1 and the actuator base 4 to form the screw hole 14. It is done by screwing.

The inclination of the actuator base 4 is adjusted by pressing the circular hole 22 into the convex portion 20 by the force of the compression spring 15 and by adjusting the two adjusting screws 16 and the convex portion 20 at three points. By adjusting the screwing depth of either or both of the two adjusting screws 16 while the actuator base 4 is supported by, the height of only the portion of the circular hole 22 fitted with the convex portion 20 is fixed. In this state, the tilt angle of the actuator base 4 is adjusted in an arbitrary direction and the orientation of the optical axis of the objective lens 2 is adjusted.

Here, as in the conventional case, the two pins 9, 1
In the structure in which 0 and the round hole 11 and the long hole 12 are fitted, as can be seen from FIG. 2A, a positional deviation occurs in the X-axis, Y-axis, and U-axis directions, that is, in all directions in the range of Δe. .
Further, as shown in FIG. 3 (A), the respective clearances Δe between the pins 9 and 10 and the surfaces of the round hole 11 and the short hole portion 12 of the long hole 12 are formed.
Since the actuator base 4 causes an error in a planar mounting angle up to a state in which is added, the maximum planar mounting error angle β of the planar actuator base 4 with respect to the optical body 1 is expressed by the equation (3). β = sin ⁻¹ (2Δe / L) (3) On the other hand, in the present embodiment, since the actuator base 4 is fixed without the clearance Δe in the circular hole 22 that fits with the convex portion 20, the actuator base 4 is fixed as shown in FIG. As can be seen from (C), the position of the fitting portion is substantially unchanged in all directions, and the positioning accuracy is much improved as compared with the conventional case. Further, as shown in FIG. 3 (B), the mounting error angle β on the plane becomes as shown in the equation (4) due to the gap Δe between the pin portion 21 and the minor diameter portion forming surface of the elongated hole 23. . β = sin ⁻¹ (Δe / L) (4) As can be seen from the comparison between the formula (3) and the formula (4), according to the present embodiment, the mounting error angle β on the plane is larger than that of the conventional example. Is halved.

FIG. 3C is a plan view showing the relative positional relationship among the objective lens 2, the convex portion 20, and the pin portion 21, and the actuator fitted to the convex portion 20 as in this embodiment. Since the portion of the circular hole 22 of the table 4 is fixed, it is clear that if the objective lens 2 is provided as close as possible to the portion of the circular hole 22, the positional accuracy can be further improved.

In FIG. 3C, the actuator base 4
The x-axis is one side, the direction is not perpendicular to this and the y-axis is
The center of the convex portion 20 (circular hole 22) is point A, the center of the objective lens 2 is point B, the center of the pin portion 21 is point C, and the distances between A and B in the x and y axis directions are g and h, respectively. , X between A and C
If the distances in the axial and y-axis directions are i and j, respectively, AB
If the distance L _AB between them is shorter than the distance L _AC between A and C, that is, if L _AC = (i ² + j ² ) ^1/2 > L _AB = (g ² + h ² ) ^1/2 , then point B The positioning accuracy of (objective lens 2) is C
Than the gap between the pin portion 21 and slots 23 at the point, the gap becomes a one position shift multiplied by L _AB / L _AC occurs, as this ratio is small, positional deviation of the objective lens 2 becomes small, the objective The positioning accuracy of the lens 2 is improved. As shown in the embodiment, if the ratio L _AB / L _{AC is set} to about 1/4, it is reduced to about 1/4 as compared with the conventional positional displacement. The lower limit of this ratio L _AB / L _AC is determined by the area occupied by the mounting members of the constituent members of the actuator 3, and in practice, it must be set to about 1/10 or more. Further, in order to obtain the effect of the present invention, it is preferable that the ratio L _AB / L _AC be 1/2 or less, and more preferably 1/5 to 2 /.
It is 5.

While the positioning accuracy is improved in this way,
The convex portion 20 and the circular hole 22 can be tilted without limitation within an angle range that is actually required, and in any tilt direction of the X axis, the Y axis, or the U axis in FIG. Only the limit of the inclination determined by the gap between the pin portion 21 and the elongated hole 23 and the thickness of the actuator base 4 is imposed,
The tilt is not restricted in any tilt direction other than the X axis and the Y axis.

In this embodiment, the convex portion 20 and the compression spring 15 are arranged on the opposite sides of the line connecting the two adjusting screws 16, and the convex portion 20 is applied by the force of the compression spring 15. By adopting a configuration in which the circular hole 22 is press-fitted to the 20, the number of the adjusting screws 16 is reduced from the conventional three to two, and the number of the compression springs 15 is also reduced from three to one. The number of parts of the mounting member of the base 4 is reduced. In addition, in this embodiment, FIG.
As shown in (B), the opening 1 is formed on the bottom surface of the optical body 1.
Along with the provision of "a" and a part of the actuator 3 is dropped into the opening 1a, the overall thickness of the optical head is reduced.

FIG. 4A shows another embodiment of the present invention,
A protrusion 20 is provided on the protrusion 4a of the actuator base 4, a conical circular hole 22 is provided in the optical body 1, and
The pin portion 21 is provided on the actuator base 4, and the elongated hole 23 is provided on the optical body 1. In this way, the convex portion 20
(Or the pin portion 21) does not necessarily have to be provided in the optical body 1, and these may be provided in either one of the actuator base 4 and the optical body 1, and the hole 22 (or the elongated hole 23) may be provided in the other.

In the present invention, the circular hole fitted into the convex portion 20 may be a circular hole 22A having an arcuate inner surface R, as shown in FIG. 4B, instead of the conical hole. Further, in the case of having such an arcuate inner surface R, the convex portion may be a conical convex portion 20A as indicated by a chain double-dashed line. Further, as shown in FIG. 4C, a circular hole 22B having the same diameter over the entire length of the hole, or a circular (spherical) concave portion 22C instead of the hole as shown in FIG. 4D may be used. Also,
When forming the concave portion 22C of FIG. 4D, the curvature of the convex portion 20 and the radius of curvature of the concave portion 22C do not have to be exactly the same, and a slight difference is allowable to the extent that the concave and convex fitting portion does not shift in position. To be done. In addition, as shown in FIG.
0B is formed in a conical shape, and a tapered circular concave portion 22D (this concave portion 22) provided on the actuator base 4 is formed at the tip thereof.
The taper angle of D is made larger than the taper angle of the convex portion 20B), and the actuator base 4 may be combined around the center so that the actuator base 4 can be tilted in any direction over a predetermined angle range.

FIG. 5A is a plan view showing another embodiment of the present invention, and FIG. 5B is a sectional view taken along line H-H of FIG. By providing the enlarged taper portion 23a on the side forming surface, the limitation of the inclination due to the contact between the inner surface of the elongated hole 23 and the pin portion 21 is eliminated. When the tiltable angle θ of the actuator base 4 is t ₁ when the thickness of the non-tapered portion is θ, sin = sin ⁻¹ (Δe / t ₁ )
And the tiltable angle θ can be increased. In addition, the pin portion 21 and the long hole 2 in the long hole 23
Since the gap Δe with respect to 3 can be reduced, the positioning accuracy is further improved.

Instead of providing the tapered portion 23a in the elongated hole 23, the same effect can be obtained by forming the tapered portion 21a in the pin portion 21 as shown in FIG. 5 (C).

FIG. 5D shows another embodiment of the present invention.
A pin portion 20C is provided in place of the convex portion 20 in the embodiment of FIG. 5 (A), and a taper portion 22b is provided in a hole 22A through which the pin portion 20C is inserted. As in the case of 20, the restriction on the inclination in the round hole 22A is relaxed, so that the gap Δe between the pin portion 20C and the circular hole 22A can be reduced, and the positioning accuracy can be improved and the restriction on the inclination can be relaxed at the same time. it can. The provision of either one of the taper portions 22b and 23a, but not one of the taper portions 22b and 23a, can improve the positioning accuracy and reduce the inclination limitation.

[0030]

According to the first aspect of the present invention, the fitting position of the spherical or conical convex portion and the concave portion or hole is substantially unchanged in any inclination direction of the actuator base.
The position changes only in the fitting part of the long hole and the pin part, so that the actuator base is displaced by the gap between the pin of the hole at each position of the two pins as in the conventional case. Positioning accuracy is higher than when it is raised. Further, in the fitting portion between the convex portion and the concave portion or hole, the range of rotation of the actuator base around the convex portion is wide, and the only limitation on the inclination is the gap between the pin portion and the elongated hole. As a result, the limitation on the inclination is relaxed, and the margin of the adjustment angle can be increased.

According to the second aspect, the fitting portion between the convex portion and the circular hole or the like is used as a receiving point for the force of the compression spring, and the actuator base is attached to the optical body by utilizing it as one inclined fulcrum. Therefore, the number of parts of the actuator base mounting member such as the adjusting screw and the compression spring can be reduced.

According to the third aspect, since the circular hole or the elongated hole fitted with the pin portion is tapered, it is possible to increase the margin of the adjustment angle of the actuator base. In addition, because you can increase the margin of adjustment angle,
The gap between the pin portion and the circular hole or the long hole can be reduced, and the positioning accuracy can be improved.

According to a fourth aspect, a spherical or conical convex portion is provided in place of the pin portion that fits into the circular hole in the third aspect, and a circular or spherical shape is provided on the other side so as to correspond to the convex portion. Since the concave portion or hole is provided and the convex portion is fitted into the concave portion or hole, the positioning accuracy is further improved.

According to a fifth aspect, instead of forming the circular hole or the elongated hole in a tapered shape, at least one of the first and second pins is formed in a tapered shape. The positioning accuracy can be improved and the adjustment angle margin can be increased.

[Brief description of drawings]

FIG. 1A is an exploded perspective view showing an embodiment of a positioning mechanism for an objective lens with respect to an optical body according to the present invention;
(B) is a longitudinal sectional view thereof.

2A is a plan view showing an engagement relationship between a conventional pin and a hole, FIG. 2B is a sectional view taken along line EE of FIG. 2A, and FIG. 2C is a convex portion and a pin portion of this embodiment. A plan view showing the engagement relationship with the holes,
(D) is a FF sectional view of (C).

FIG. 3A is a plan view for explaining an error in the mounting angle of the actuator base on the plane due to the existence of a gap between the conventional pin and the hole, and FIG. 3B is a view for explaining the error in the mounting angle in the case of the present invention. FIG. 6C is a plan view for explaining the dimensional relationship of the distance between the objective lens, the convex fitting portion and the pin fitting portion in the present embodiment.

FIG. 4A is a vertical cross-sectional view showing another embodiment of the present invention,
(B)-(E) is sectional drawing explaining the other example of the fitting structure of the convex part and circular hole or recessed part in this invention.

5A is a plan view showing another embodiment of the present invention, FIG.
(B) is a sectional view taken along line H-H of (A), (C) is a sectional view showing a modification of (B), (D) is a plan view showing another embodiment of the present invention, and (E) is ( It is a GG sectional view of D).

FIG. 6 is an exploded perspective view showing a conventional positioning mechanism for an optical body of an objective lens.

[Explanation of symbols]

1: Optical body, 2: Objective lens, 3: Actuator, 4: Actuator base, 13: Through hole, 14: Screw hole, 15: Compression spring, 16: Adjustment screw, 20, 20A,
20B: convex portion, 21: pin portion, 21a: tapered portion, 2
2, 22A, 22B: circular hole, 22b: tapered portion, 2
2C, 22D: circular concave portion, 23: long hole, 23a: tapered portion

Claims (5)

[Claims] 1. A mechanism for positioning an actuator of an objective lens with respect to an optical body of an optical head and adjusting a tilt of the actuator with respect to the optical body, wherein one of the optical body and the actuator base has a spherical shape or While providing a conical convex portion, the convex portion is fitted into a circular concave portion or hole provided on the other side, and the actuator base is tiltable in all directions with respect to the optical body with the fitting portion as a center, A pin portion is provided on one of the body or the actuator base, and the pin portion is fitted into an elongated hole provided on the other side, and the distance between the convex portion and the center of the objective lens is set to the convex portion and the pin portion. An objective lens positioning mechanism for an optical disk device, which is shorter than the distance. 2. The adjusting screw according to claim 1, wherein the adjusting screw is inserted into each of the two holes provided in one of the optical body and the actuator base and is screwed into the screw hole provided in the other. A compression spring is interposed between the actuator base and the optical body on the side opposite to the convex portion with respect to the line connecting the two, and the convex portion and the circular concave portion or hole are brought into pressure contact with each other by the force of the compression spring. Objective lens positioning mechanism for optical disk device. 3. A mechanism for positioning an actuator of an objective lens with respect to an optical body of an optical head and adjusting an inclination of the actuator with respect to the optical body, wherein a pin portion is provided on either the optical body or the actuator base. Provided, the pin portion is fitted into a circular hole provided in the other, another pin portion is provided in either one of the optical body or the actuator base, and the other pin portion is provided in the elongated hole provided in the other. An objective lens positioning mechanism for an optical disk device, wherein at least one of a hole and an elongated hole corresponding to each of the pin portions is formed in a tapered shape while being fitted. 4. The optical body or the actuator base according to claim 3, wherein:
A spherical or conical convex portion is provided instead of the pin portion that fits into the circular hole, and the convex portion is fitted into the circular concave portion or hole that is provided on the other side. An objective lens positioning mechanism for an optical disk device, wherein an actuator base is tiltable in all directions with respect to an optical body. 5. The optical disk device according to claim 3, wherein at least one of the first and second pins is formed in a tapered shape instead of forming the hole or the elongated hole in a tapered shape. Objective lens positioning mechanism.