JP3312092B2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an objective lens driving device used for an optical disk device for recording and reproducing information.

[0002]

2. Description of the Related Art An optical disk drive of this type is provided with an objective lens driving device for moving an objective lens in two directions, a focus direction and a tracking direction. Here, the focus direction refers to a direction perpendicular to the surface of the optical disc, and the tracking direction refers to a direction perpendicular to both the focus direction and the rotation direction of the optical disc.

FIG. 4 is a perspective view showing an example of the configuration of a conventional objective lens driving device.

In FIG. 4, an objective lens holder 12 for supporting an objective lens 11 is attached to a support portion 16 by a total of four leaf springs 13 with a degree of freedom mainly in a focus direction and a tracking direction.
A focus coil 14 and a tracking coil 15 are fixed to the objective lens holder 12. The focus coil 14 and the tracking coil 15 constitute an actuator that drives the objective lens 11 in the focus direction and the tracking direction in combination with the magnetic circuit 21. Objective lens 11, objective lens holder 12,
The focus coil 14 and the tracking coil 15 are collectively called an objective lens driving device movable unit.

During operation of the apparatus, an appropriate focus servo and tracking servo are applied to the actuator.

The objective lens holder 12 for holding the objective lens 11 is configured to be movable with a predetermined movable range in the focus direction. The movable range is set so that even if the holder 12 moves to the position closest to the optical disk, the objective lens 11 and the optical disk do not come into contact with each other. The objective lens driving device is provided with a stopper (not shown) so that the objective lens holder 12 does not move beyond the movable range.

In this conventional example, the objective lens holder 12
Is supported by four leaf springs 13, but this method is known to be most suitable for miniaturization as a configuration of an objective lens driving device having two degrees of freedom. Other supporting methods include a method using a leaf spring, a method using a resin hinge, and a method using a support shaft.

In recent years, with the spread of portable information processing devices,
There is a demand for a thin information recording / reproducing apparatus using an optical disk. However, in the above-described conventional objective lens driving device, the objective lens and the optical disk are configured so as to be inaccessible within a predetermined distance in order to avoid collision between the objective lens and the optical disk. There are limits.

In a general optical disk device, the distance between the objective lens and the optical disk surface is set to 1 to 2 mm. On the other hand, if the distance between the objective lens and the optical disk surface can be made shorter, for example, 0.5 mm, the focal length of the objective lens can be shortened.
And the light beam diameter determined by the focal length can be reduced, and the device can be significantly thinned.

However, if the distance between the objective lens and the surface of the optical disk is shortened, there is a possibility that the objective lens and the surface of the optical disk come into contact with each other when the focus servo is released due to disturbance or the like.

FIG. 5 is a view for explaining the behavior when the objective lens and the optical disk surface are in contact with each other. When the objective lens 11 of the objective lens driving device as shown in FIG. 5A contacts the optical disk surface 31, the influence of the rotation of the optical disk,
In addition, since the point of contact between the objective lens 11 and the optical disk surface 31 and the center of gravity of the movable portion of the objective lens driving device are different, the objective lens holder rotates and supports the objective lens holder as shown in FIG. An abnormal moment force is applied to the leaf spring 13.

Such a force is likely to deform the leaf spring 13 and damage the objective lens driving device. Further, since the objective lens and the objective lens holder come into contact with the optical disk surface, there is a possibility that the objective lens and the optical disk surface may be damaged.

Japanese Patent Application Laid-Open No. 5-197982 proposes a method of attaching a buffer member protruding from the objective lens near the objective lens or near the center of gravity of the movable portion of the objective lens driving device as a measure against damage to the surface of the objective lens and the optical disk. Have been.

[0014]

Problems to be Solved by the Invention
Japanese Patent Laid-Open Publication No. 2 (1999) -1995 discloses a method of attaching a buffer member near an objective lens. However, here, since the contact point between the optical disk surface and the cushioning material is different from the center of gravity of the movable portion of the objective lens driving device, the objective lens holder rotates similarly to the above-described example. As another example, a method of attaching a buffer member to the vicinity of the center of gravity of the movable portion of the objective lens driving device is shown, but the contact portion between the optical disk surface and the buffer material also coincides with the center of gravity of the movable portion of the objective lens driving device. Therefore, the objective lens holder rotates around the center of gravity of the movable portion of the objective lens driving device due to the rotational force of the optical disk.

When the objective lens holder rotates, an abnormal force is applied to the suspension supporting the objective lens holder, and the suspension may be damaged. In addition, since there is a possibility that a portion other than the cushioning material may come into contact with the optical disk surface, the optical disk surface may be damaged.

A shaft-sliding type objective lens driving device having a support shaft does not cause rotation of the objective lens holder, which is currently a problem, but the shaft-sliding type objective lens driving device is originally downsized, There is a drawback that it is difficult to make the device thinner, which departs from the object of the present invention, which is to make the device thinner.

In view of these problems, the present invention prevents the objective lens and the optical disk surface from being damaged by rotating when the objective lens and the optical disk surface come into contact with each other. It is an object of the present invention to make it possible to have a close structure and to make an optical disk device thinner.

[0018]

In order to achieve the above object, an objective lens driving apparatus according to the present invention comprises: an objective lens for condensing a light beam on an optical disk; an objective lens holder for holding the objective lens; An objective lens driving device comprising: a suspension that elastically supports the holder so as to be movable in a focus direction and a tracking direction ; and an optical axis of the objective lens and the objective lens driving device.
So that straight lines passing through the center of gravity of the movable part do not match
At the same time, on the optical disk side of the objective lens holder, perpendicular to the surface of the optical disk and including a surface passing through the center of gravity of the movable part of the objective lens driving device, protruding toward the optical disk from the objective lens, and It has at least two projecting portions arranged so that the distances from the optical disk surface are substantially equal.

The objective lens includes an objective lens for condensing a light beam on the optical disk, an objective lens holder for holding the objective lens, and a suspension for elastically supporting the objective lens holder so as to be movable in a focus direction and a tracking direction. that the objective lens driving device, the pair
The optical axis of the object lens and the center of gravity of the movable part of the objective lens driving device
And the vertex position of a triangle on the optical disk side of the objective lens holder, which is perpendicular to the optical disk surface and passes through the center of gravity of the movable part of the objective lens driving device, passes through the inside. Disposed so as to protrude toward the optical disc from the objective lens and have a substantially equal distance from the optical disc surface;
It has at least three projecting portions.

The tip of the protruding portion on the optical disk side is made of a slidable material or a nonwoven fabric, and the nonwoven fabric contains at least one of rayon or polyester. It is characterized by.

[0021]

FIG. 1 shows a first embodiment of an objective lens driving device according to the present invention.

As in the conventional example shown in FIG. 4, the objective lens holder 12 for supporting the objective lens 11 is attached to the support section 16 with a degree of freedom mainly in the focus direction and the tracking direction by a total of four leaf springs 13. Installed. A focus coil 14 and a tracking coil 15 are fixed to the objective lens holder 12. Focus coil 14 and tracking coil 1
5 is combined with the magnetic circuit 21 and the objective lens 11
Are configured in the focus direction and the tracking direction. Also, the light of the objective lens 11
To the surface of the optical disk through the axis and the center of gravity 101 of the movable part
The vertical straight lines do not coincide with each other.

During operation of the apparatus, an appropriate focus servo and tracking servo are applied to the actuator of the objective lens driving device. The distance between the objective lens 11 and the optical disk surface during operation of the apparatus is set to about 0.5 mm.

The objective lens holder 12 for holding the objective lens 11 has a distance of about 0.2 m from the optical disc surface.
There are provided two projecting portions 17 which are m and are arranged so as to include a part of a surface 201 which is perpendicular to the tracking direction and passes through the center of gravity 101 of the movable portion of the objective lens driving device.

A plane 201 which is perpendicular to the center of gravity 101 of the movable section and passes through the center of gravity 101 of the movable section in FIG.
Is illustrated for explanation and has no entity.

The protruding portion 17 is made of a slidable material at the portion closest to the optical disk. In this embodiment, a fluororesin is used as the slidable material.

The operation of this embodiment when a large impact is applied during the operation of the apparatus will be described with reference to FIG. FIG.
(A) is a side view of the objective lens driving device of the present invention in a normal operation state. FIG. 2B is a side view showing a state in which a large impact is applied to the apparatus, the focus servo is released, and the objective lens holder 12 and the optical disk surface 31 are in contact. At this time, two projecting portions 17 provided on the objective lens holder 12 actually contact the optical disk surface 31. Since the two projecting portions 17 are almost simultaneously in contact with the surface of the optical disk, and are arranged perpendicular to the tracking direction and including a part of the surface passing through the center of gravity of the movable portion of the objective lens driving device, At the time of contact, there is no possibility that an abnormal moment force in the rotation direction of the optical disc is applied to the objective lens holder 12. Therefore, the objective lens driving device is not damaged, and the objective lens does not contact the optical disk surface.

The portions of the two projecting portions 17 which come into contact with the surface of the optical disk are made of a slidable material, so that the friction when the projecting portion 17 comes into contact with the surface of the optical disk is reduced. Surface damage can be minimized.

In this embodiment, 2 is arranged so as to be perpendicular to the tracking direction of the objective lens holder 12 and to include a part of a plane passing through the center of gravity of the movable portion of the objective lens driving device.
Although the projecting portions 17 are provided, three or more projecting portions may be provided.

Further, in the present embodiment, the portion of the protruding portion 17 which is in contact with the surface of the optical disk is made of a fluorine-based resin, but may be made of any slidable material. You may. In the case of a non-woven fabric, dust and dirt on the surface of the optical disk that cause scratches can be taken into the non-woven fabric and removed from the surface of the optical disk.
Further, since the nonwoven fabric has appropriate elasticity, the nonwoven fabric has an effect of reducing the impact at the time of contact. Generally, paper or the like can be considered as a fiber constituting the nonwoven fabric, but rayon, polyester, or a material containing them is desirable from the viewpoint of durability, slidability, and productivity.

FIG. 3 shows a second embodiment of the objective lens driving device according to the present invention.

As in the conventional example shown in FIG. 4, the objective lens holder 12 for supporting the objective lens 11 is attached to the support section 16 with a degree of freedom mainly in the focusing direction and the tracking direction by a total of four leaf springs 13. Installed. A focus coil 14 and a tracking coil 15 are fixed to the objective lens holder 12. Focus coil 14 and tracking coil 1
5 is combined with the magnetic circuit 21 and the objective lens 11
Are configured in the focus direction and the tracking direction. Also, the light of the objective lens 11
To the surface of the optical disk through the axis and the center of gravity 101 of the movable part
The vertical straight lines do not coincide with each other.

During operation of the apparatus, an appropriate focus servo and tracking servo are applied to the actuator of the objective lens driving device. The distance between the objective lens 11 and the optical disk surface during operation of the apparatus is set to about 0.5 mm.

The objective lens holder 12 for holding the objective lens 11 has a distance of about 0.2 m from the optical disc surface.
m are provided at three vertices of a triangle 202 such that a straight line 102 perpendicular to the optical disk surface passing through the center of gravity 101 of the movable portion of the objective lens driving device passes through the inside thereof. Are located.

A center of gravity 101 of the movable part and a straight line 10 passing through the center of gravity of the movable part 101 and perpendicular to the optical disk surface (not shown)
2 and a triangle 202 through which the straight line 102 passes.
Is illustrated for explanation, and there is no entity.

The protruding portion 17 is made of a slidable material at the portion closest to the optical disk. In this embodiment, a fluororesin is used as the slidable material.

When a large shock is applied during operation of the apparatus,
The focus servo is released, and the objective lens holder 12 and the optical disk surface come into contact. At this time, three projecting portions 17 provided on the objective lens holder 12 actually contact the optical disk surface. These three projecting portions 17 are arranged at the apexes of a triangle 202 such that a straight line 102 perpendicular to the optical disk surface passing through the center of gravity 101 of the movable portion of the objective lens driving device passes through the inside thereof almost simultaneously with the optical disk surface. Therefore, upon contact, the objective lens holder 12 is positioned parallel to the optical disk surface, and there is no possibility that an abnormal moment force is applied. Therefore, the objective lens driving device is not damaged.

The portions of the three projecting portions 17 which come into contact with the optical disk surface are made of a slidable material, so that the friction between the projecting portions 17 and the optical disk surface is reduced, and the optical disk surface is not damaged. Can be minimized.

In this embodiment, a straight line 102 perpendicular to the optical disk surface that passes through the center of gravity 101 of the movable portion of the objective lens driving device
Are provided on the objective lens holder 12 at three vertices of the triangle 202 passing through the inside of the triangle 202. If at least three positions are disposed at the vertices of the triangle, four or more positions are provided. May be provided.

In this embodiment, the portion of the protruding portion 17 that comes into contact with the surface of the optical disk is made of a fluororesin. You may. In the case of a non-woven fabric, dust and dirt on the surface of the optical disk that cause scratches can be taken into the non-woven fabric and removed from the surface of the optical disk.
Further, since the nonwoven fabric has appropriate elasticity, the nonwoven fabric has an effect of reducing the impact at the time of contact. Generally, paper or the like can be considered as a fiber constituting the nonwoven fabric, but rayon, polyester, or a material containing them is desirable from the viewpoint of durability, slidability, and productivity.

[0041]

As described above, the objective lens driving device of the present invention is provided with a plurality of projecting portions appropriately arranged on the objective lens holder, so that a plurality of projecting portions are formed before the objective lens collides with the optical disk. At almost the same time, they come into contact with the optical disk surface. Therefore, an abnormal moment force is not applied to the leaf spring supporting the movable portion of the objective lens driving device, and damage to the objective lens and deformation of the leaf spring can be prevented.

Further, since at least a part of the protruding portion is made of a slidable material or a nonwoven fabric, damage to the objective lens driving device and the optical disk when the objective lens holder comes into contact with the optical disk surface can be minimized. Can be suppressed. Therefore, the distance between the objective lens and the surface of the optical disk during operation of the apparatus can be made shorter than before, and the apparatus can be made thinner. In particular, movable with the optical axis of the objective lens
A straight line passing through the center of gravity and perpendicular to the surface of the optical disk
In the case of a non-matching objective lens drive,
And miniaturization are remarkable.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a first embodiment of an objective lens driving device according to the present invention.

FIG. 2 is a diagram illustrating a state at the time of contact between an objective lens holder and an optical disc in FIG. 1;

FIG. 3 is a perspective view illustrating a second embodiment of the objective lens driving device according to the present invention.

FIG. 4 is a perspective view illustrating a conventional example.

FIG. 5 is a side view illustrating a problem to be solved by the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Objective lens 12 Objective lens holder 13 Leaf spring 14 Focus coil 15 Tracking coil 16 Support part 17 Projecting part 21 Magnetic circuit 31 Optical disk surface 101 Moving part center of gravity

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-128559 (JP, A) JP-A-63-269333 (JP, A) JP-A-7-134832 (JP, A) 49732 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) G11B 7/09

Claims (4)

(57) [Claims] An objective lens for focusing a light beam on an optical disk, an objective lens holder for holding the objective lens, and a suspension for elastically supporting the objective lens holder so as to be movable in a focus direction and a tracking direction. , The optical axis of the objective lens and the objective lens
Perpendicular to the surface of the optical disk through the center of gravity of the movable part of the drive unit
In the objective lens driving device, such straight lines not configured to match the previous SL The optical disc side of the objective lens holder, a plane passing through the movable portion center of gravity of the vertical and and the objective lens driving device with respect to the surface of the optical disc at a position including the distance from the projecting optical disk side than the objective lens and the optical disc surface is arranged such that approximately equal, when at least two protruding parts together forming the projecting portion
So that at least one line segment intersects the straight line.
An objective lens driving device, wherein a projecting portion is arranged . 2. An objective lens for condensing a light beam on an optical disk, an objective lens holder for holding the objective lens, and a suspension for elastically supporting the objective lens holder so as to be movable in a focus direction and a tracking direction. , The optical axis of the objective lens and the objective lens
Perpendicular to the surface of the optical disk through the center of gravity of the movable part of the drive unit
In the objective lens driving device, such straight lines not configured to match the previous SL The optical disc side of the objective lens holder, a straight line passing through the movable portion center of gravity of the vertical and and the objective lens driving device on the optical disk surface through the inner An objective lens driving device having at least three protruding portions at the vertices of a triangle, protruding toward the optical disk from the objective lens and arranged so that the distances from the optical disk surface are substantially equal. 3. The non-woven fabric at the tip of the protruding portion on the optical disk side.
Alternatively, the objective lens driving device according to claim 2. 4. The objective lens driving device according to claim 3, wherein the nonwoven fabric includes at least one of rayon and polyester.