JPH08329509A - Optical pickup device - Google Patents

Abstract

PURPOSE: To make the modulus of bending elasticity and the slidability of a lens holder compatible both at a high standard level. CONSTITUTION: The optical pickup device has the lens holder 3 for holding an objective lens 2 and a supporting shaft 5 to be inserted into a bearing hole provided on this lens holder 3, and the lens holder 3 is held movably in the direction of the supporting shaft 5 and also ocillatably around the supporting shaft 5. Then, the lens holder 3 is formed of a resin of high rigidity 3a, and also a bearing surface 4 which is at least to come in contact with the supporting shaft 5 of the lens holder 3 is constituted of a slidable resin 3b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device incorporated in an optical disk device or the like. More specifically, the present invention relates to an improvement of a lens holder that holds an objective lens of an optical pickup device.

[0002]

2. Description of the Related Art As an optical pickup device incorporated in an optical disc device for reproducing an optical disc which is a digital recording medium, there is a conventional optical pickup device, for example, Japanese Patent Laid-Open No. 1-30702.
Some of them are disclosed in Japanese Patent No. In this optical pickup device 101, as shown in FIGS. 4 to 6, a resin lens holder 102 is supported rotatably around a support shaft 103 and movable along the support shaft 103. A pair of focus drive coils 104, 104 and a pair of tracking drive coils 105, 105 are fixed to the lens holder 102.

On the other hand, a pair of magnets 107, 107 facing the coils 104, 105 are fixed to a yoke 106 fixing the support shaft 103. Therefore, by applying a drive current to the focus drive coil 104, a thrust force in the direction of the support shaft 103 acts on the lens holder 102, and the lens holder 102 moves to perform focusing. Further, by supplying a drive current to the tracking drive coil 105, the support shaft 103 is attached to the lens holder 102.
A surrounding moment acts, and the lens holder 102 moves to perform tracking.

[0004]

However, in order to increase the speed of the pickup, it is necessary to increase the high-order resonance frequency of the lens holder 102, which increases the bending elastic modulus of the lens holder 102. There is a need. That is, when the lens holder 102 is resin-molded, it is necessary to increase the bending elastic modulus of the molded product by adding a filler for modification such as carbon fiber, glass fiber or whisker to the resin before molding. On the other hand, in order to improve the responsiveness of focusing and tracking,
It is necessary to secure the slidability of the lens holder 102 and reduce the frictional resistance to the support shaft 103. However, the lens holder 102 molded from a resin with a filler added
May deteriorate the slidability and the responsiveness of focusing and tracking. That is, the lens holder 102
The improvement in bending elastic modulus and the improvement in slidability tend to contradict each other, and it has been difficult to achieve both at a high level.

Further, the lens holder 102 has a support shaft 10
It is difficult to obtain a bearing hole with high dimensional accuracy by injection molding of a resin to which a filler is added. It is difficult to ensure the roundness of less than 5 μm). That is, also from this point, it is difficult to ensure smooth movement of the lens holder 102 with respect to the support shaft 103. In this case, it is conceivable to machine the bearing surface 108 to secure a desired dimension, but when the resin to which the filler is added is cut and ground, the filler is exposed on the processed surface. Slidability deteriorates, and it is difficult to ensure smooth movement of the lens holder 102.

According to the present invention, both the elastic modulus and the slidability of the lens holder can be made compatible at a high level, and
An object of the present invention is to provide an optical pickup device capable of smoothly moving a lens holder and improving responsiveness.

[0007]

In order to achieve the above object, the present invention has a lens holder for holding an objective lens and a support shaft inserted into a bearing hole provided in the lens holder, In an optical pickup device in which a holder is held so as to be movable in the support axis direction and swingable around the support axis, the lens holder is molded from high-rigidity resin, and at least the bearing surface of the lens holder that contacts the support axis is It is made of slidable resin.

[0008]

Therefore, the frictional resistance between the bearing surface of the lens holder and the support shaft is reduced, and the lens holder slides smoothly. Further, since the portion other than the portion formed of the slidable resin is formed of the high-rigidity resin, the bending elastic modulus of the lens holder increases.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

1 to 3 show an embodiment of an optical pickup device according to the present invention.
Has a lens holder 3 that holds the objective lens 2 and a support shaft 5 that is inserted into a bearing hole provided in the lens holder 3 to support the lens holder 3.

Most of the lens holder 3 is molded with a high-rigidity resin 3a, and at least a portion of the bearing surface 4 that contacts the support shaft 5 is molded with a slidable resin 3b to be integrated. That is, the lens holder 3 is a two-color molded product, and the peripheral portion of the bearing surface 4 is molded with the slidable resin 3b, and the other portion is molded with the high-rigidity resin 3a.

Here, the high-rigidity resin 3a is, for example, PPS.
It is a (polyphenylene sulfide) type composite material (for example, trade name: Torelina A-310M, manufactured by Toray Industries, Inc.) filled with a predetermined amount of a modifier for improving the elastic modulus. Examples of the modifier include carbon fiber,
There are glass fibers, whiskers, ceramics, etc. Further, the filling rate of the modifier is increased as much as possible within the range where resin molding is possible. In this embodiment, the filling rate of the high rigidity resin 3a is 60 to 7.
A value of 0 wt% is desirable, more preferably 65 wt%
Before and after. This is because if the filling rate is less than 60 wt%, it is insufficient to increase the elastic modulus, and if it exceeds 70 wt%, molding becomes impossible.

The flexural modulus of the high-rigidity resin 3a is preferably in the range of 15 to 50 GPa, more preferably about 40 GPa. This flexural modulus affects the higher resonance frequencies. That is, as the flexural modulus increases, the higher resonance frequency tends to increase. Higher resonance frequency is an important characteristic of pickup actuator,
The higher the pickup speed in the future, the higher it needs to be.

The slidable resin 3b is made of, for example, PTFE.
A material having good slidability, such as (polytetrafluoroethylene), or a slidable material that does not contain PTFE. Surface accuracy of these materials can be obtained by cutting or grinding. In this embodiment, as the slidable resin 3b,
For example, PPS type (for example, trade name: Torelina A-
515, manufactured by Toray Industries, Inc.) is used. By using the same PPS resin as the high-rigidity resin 3a, it is possible to integrate the slidable resin 3b and the high-rigidity resin 3a by two-color molding. Further, since the slidable resin 3b is not filled with the modifier, it is easy to obtain a desired dimensional accuracy by injection molding, and the roundness of the bearing surface 4 is a good value even if the subsequent machining is unnecessary. become.

As a result of the mounting evaluation of the lens holder 3 manufactured as described above, the roundness of the bearing surface 4 could be 4 μm without adjusting the dimension by cutting or the like. The higher resonance frequency at this time is 20 kHz.
It was z.

On the outer peripheral surface of the lens holder 3, a pair of focus drive coils 7 and 7 and a pair of tracking drive coils 8 and 8 are fixed. A balancer 6 is fixed to the lens holder 3 on the opposite side of the objective lens 2 with the support shaft 5 interposed therebetween.

The support shaft 5 is fixed to the center of the yoke 9. The support shaft 5 is coated with, for example, a PTFE-containing thermosetting resin coating material. Therefore,
The frictional resistance of the lens holder 3 with respect to the support shaft 5 has a small value, and the lens holder 3 is supported so as to be movable in the axial direction of the support shaft 5 and swingable around the axis.

A pair of magnets 10 are attached to the yoke 9. Each magnet 10 is arranged to face a set of the focus drive coil 7 and the tracking drive coil 8. Each magnet 10 is divided into a focusing magnet portion facing the focusing driving coil 7 and a tracking magnet portion facing the tracking driving coil 8. In each of the focusing magnet parts, the N pole and the S pole are arranged side by side in the axial direction of the support shaft 5. Further, in each tracking magnet portion, an N pole and an S pole are arranged side by side in the circumferential direction.

The focus drive coil is formed in a horizontally long rectangle, and its long side is arranged so as to face each magnetic pole of the focus magnet section. Further, the tracking drive coil is formed to be a horizontally long and vertically long rectangle, and the long side thereof is arranged so as to face each magnetic pole of the tracking magnet portion.

Another yoke 11 is fixed to the yoke 9.

When a drive current flows through each focus drive coil 7 of the optical pickup device 1, a line of magnetic force is changed between the focus drive coil 7 and each focus magnet portion, and a thrust force in a direction along the axis of the support shaft 5 is generated. To do. The thrust is equally generated for the pair of magnets 10, and the lens holder 3
Are moved along the support shaft 5. The bearing surface 4 of the lens holder 3 is made of slidable resin 3b, and the supporting shaft 5
Is coated with a thermosetting resin paint in which PTFE (commonly called Teflon) is dispersed. Therefore, the frictional resistance acting between the lens holder 3 and the support shaft 5 is extremely small, and the lens holder 3 moves quickly and smoothly to perform the focusing operation.

When a drive current flows in each tracking drive coil 8, a line of magnetic force is changed between each tracking drive coil 8 and each tracking magnet portion, and a thrust force along the circumferential direction of the support shaft 5 is generated. The thrust is equally generated in the pair of magnets 10 and causes the lens holder 3 to swing around the support shaft 5. As described above, the bearing surface 4 of the lens holder 3 is made of the slidable resin 3b, and the support shaft 5 is coated with the thermosetting resin coating material.
The swinging around the support shaft 5 is smooth and quick, and the tracking operation is smoothly performed.

The above-described embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, a high-rigidity resin 3a forming the lens holder 3
As a phenolic high elasticity material (for example, 30% phenolic resin, 70% carbon fiber, 40 GP of flexural modulus)
In addition to using a), a lubricating coating (for example, trade name: S-6100, Toyo Drylube Co., Ltd.) may be used as the slidable resin 3b. In this case, first, the lens holder 3 is injection-molded with the high-rigidity resin 3a. After this,
The slidable resin 3b is formed on the bearing surface 4 of the molded lens holder 3.
Is applied and baked, and the layer of the slidable resin 3b thus formed is machined by a method such as cutting or grinding to dimension the bearing surface 4. Even when the lens holder 3 is manufactured in this manner, as in the case described above, the frictional resistance between the bearing surface 4 of the lens holder 3 and the support shaft 5 becomes extremely small, and the movement of the lens holder 3 is smooth. Can be quick. As a result of mounting evaluation of the lens holder 3 manufactured in this way, the roundness of the bearing surface 4 can be adjusted to 1.5 μm because the dimension can be adjusted by cutting. Also, the higher resonance frequency is 26 kHz.
Met.

Further, in this embodiment, the lens holder 3 is two-color molded and only the portion constituting the bearing surface 4 is made of the slidable resin 3.
Although it is molded with b, for example, the entire bearing portion of the lens holder 3 may be molded with the slidable resin 3b.

In the above optical pickup device 1,
Although the support shaft 5 coated with a thermosetting resin is used, the support shaft 5 does not necessarily have to be coated, and a metal shaft (for example, SUS material) that is not coated is supported. It may be used as the shaft 5.

Further, as the modifier for the high-rigidity resin 3a, a material having poor slidability such as ceramic may be used. Further, instead of the high-rigidity resin 3a, the lens holder 3 may be formed by using metal such as aluminum (longitudinal elastic modulus 70 GPa).

[0027]

As described above, according to the present invention, in the optical pickup device, the lens holder is formed of the high-rigidity resin, and at least the bearing surface of the lens holder which comes into contact with the support shaft is made of the slidable resin. By filling the high-rigidity resin with the modifier to improve the bending elastic modulus, the slidability of the bearing surface made of slidable resin can be secured even if the slidability deteriorates. Thus, it becomes possible to achieve both the bending elastic modulus and the slidability of the lens holder at a high level.

Further, since a high-rigidity resin having a large elastic modulus can be used, the higher resonance frequency of the pickup actuator can be increased.
Therefore, the speed of pickup can be increased.

Further, since the slidable resin does not contain the modifying material, the slidability of the machined surface can be maintained even when machining such as cutting and grinding is performed. For this reason, the dimension of the bearing surface can be adjusted by machining, the roundness is improved, and the speed of the optical pickup can be increased.

Further, when molding the bearing surface of the lens holder, a material highly filled with PTFE can be used, so that the slidability of the lens holder can be further improved, and focusing and tracking can be performed. Responsiveness is improved.

[Brief description of drawings]

FIG. 1 is a transverse sectional view showing an embodiment of an optical pickup device to which the present invention is applied.

FIG. 2 is a plan view of the optical pickup device of FIG.

3 is a vertical cross-sectional view of the optical pickup device of FIG.

FIG. 4 is a cross-sectional view of a conventional optical pickup device.

5 is a plan view of the optical pickup device of FIG. 4. FIG.

6 is a vertical cross-sectional view of the optical pickup device of FIG.

[Explanation of symbols]

 1 Optical Pickup Device 2 Objective Lens 3 Lens Holder 3a High Rigidity Resin 3b Sliding Resin 4 Bearing Surface 5 Support Shaft

Claims (1)

[Claims] 1. A lens holder for holding an objective lens,
An optical pickup device having a support shaft inserted into a bearing hole provided in the lens holder and holding the lens holder so as to be movable in the support shaft direction and swingable around the support shaft, An optical pickup device, characterized in that the lens holder is formed of a highly rigid resin, and at least a bearing surface of the lens holder that comes into contact with the support shaft is made of a slidable resin.