JPH11161984A - Objective lens drive - Google Patents

Abstract

(57) [Summary] In a shaft sliding type objective lens driving device used for various optical disk devices, the sliding and rotating lubrication characteristics are stabilized by an inexpensive manufacturing means, and the control characteristics of the objective lens are improved. The purpose is to be stable. SOLUTION: A bearing hole of an integrally molded lens holder 30 is provided with curved bearing contact portions 32 and 33 to stabilize lubrication characteristics, and an upper portion (that is, a side opposite to the insertion side of the main shaft 12). Burrs 31 provided so as not to contact the main shaft 12, and projections 3 for protecting the burrs 31
4 eliminates the need for burr treatment that hinders lubrication properties,
It is intended to reduce the manufacturing cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an objective lens driving device that drives an objective lens to perform focusing control and tracking control.

[0002]

2. Description of the Related Art Recently, an optical recording / reproducing apparatus for recording / reproducing information on / from an optical recording medium such as an optical disk has been receiving attention. In particular, various objective lens driving devices for irradiating or detecting a light beam on a recording medium, which is a key component thereof, have been proposed.

A conventional objective lens driving device is known, for example, from Japanese Patent Application Laid-Open No. 1-307029, and has a configuration as shown in the schematic diagrams of FIGS. 6, 7 and 8. .

FIG. 6 is a plan view of a conventional objective lens driving device, FIG. 7 is a sectional view thereof, and FIG. 8 is a partial sectional view of a main part thereof.

In FIGS. 6, 7 and 8, a spindle holder 9 is shown.
A substantially cylindrical lens holder 2 is slidably and rotatably mounted on a main shaft 1 arranged in the optical axis direction at a predetermined position, and the lens holder 2 is eccentric in the radial direction from the main shaft 1 described above. The objective lens 3 is fixed at a predetermined position, and the objective lens 3 can be driven integrally with the lens holder 2.

A focusing coil 4 and a tracking coil 5 are fixed to a side wall of the lens holder 2, and a driving current is supplied by a conductive pattern of the connection line 6 and the wiring board 7, and a focusing magnet (not shown)
In addition, a driving force in a sliding direction and a rotating direction is generated in the lens holder 2 by an electromagnetic driving force acting between the lens holder 2 and a tracking magnet (not shown), thereby performing a focusing control and a tracking control operation.

The main shaft 1 and the lens holder 2 constitute a slidable and rotatable bearing, and good lubrication characteristics are required for precise positioning of the objective lens 3. Therefore, the main shaft 1 uses a shaft having a circular cross section having high straightness and high surface accuracy, and some of the shafts 1 are subjected to a surface treatment for improving lubricity. The lens holder 2 is usually formed by precision molding such as injection molding or compression molding using a lubricating resin material or the like that is compatible with the main shaft 1 in order to achieve both lubrication characteristics and manufacturing costs. In order to maintain the attitude of the objective lens 3, the gap between the main shaft 1 and the bearing hole of the lens holder 2 needs to be as small as possible.
It is set to about μm. The sliding and rotating holes formed in the center of the lens holder 2 are usually straight holes having a circular cross section, that is, holes having the same diameter from the upper end to the lower end. Inevitably, there is a burr portion 10 caused by the material leaking into the gap between the mating portions of the mold during molding.

[0008]

In this objective lens driving device, as described above, in order to perform precise positioning of the objective lens 3, good lubrication characteristics are required for the bearing. However, in the conventional configuration, the lubrication characteristics of sliding or rotation are impaired by the molding distortion of the burr 10 at the end of the bearing hole of the lens holder 2 or the dust or foreign matter entered from the outside of the bearing central portion 11, and an appropriate Control operation of the objective lens position may not be performed. Therefore, it is necessary to remove burrs of the lens holder 2 and carefully clean the inside of the bearing hole before assembling, which increases the man-hour for assembling the objective lens driving device, which is expensive. In addition, the quality of the objective lens driving device is not constant and has become unstable.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide an inexpensive objective lens driving device having stable sliding and rotating lubrication characteristics.

[0010]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention limits the contact portion between a main shaft and a bearing portion formed by a lens holder, forms the contact portion with a small contact resistance, and generates a lens holder. It is configured to eliminate or reduce the influence of molding burrs. This makes it possible to obtain an objective lens driving device having a bearing with good characteristics and high reliability, in which manufacturing operations from component production to assembly are easy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention has a main shaft arranged in the optical axis direction, and a lens holder slidably and rotatably mounted on the main shaft. A bearing hole provided in a lens holder, wherein the diameter of the upper end contact portion and the lower end contact portion is small, and the diameter near the central portion is large, and the contact portion of the bearing constituted by the main shaft and the lens holder is formed. The upper and lower ends of the bearing hole of the lens holder are limited to have an effect of making the center hole less susceptible to scratches and foreign matter.

According to a second aspect of the present invention, there is provided the objective lens driving device according to the first aspect, wherein the upper end contact portion and the lower end contact portion of the bearing hole of the lens holder are formed as curved surfaces. It has the effect of improving the lubrication characteristics of the contact portion.

According to a third aspect of the present invention, there is provided a main shaft arranged in the optical axis direction, and a lens holder slidably and rotatably mounted on the main shaft. And a burr generating portion at one of both end portions of the bearing hole is arranged at an end opposite to the insertion side of the main shaft, and prevents the burr from falling down into the bearing by the insertion of the main shaft. Has an action.

According to a fourth aspect of the present invention, there is provided a main shaft arranged in the optical axis direction, and a lens holder slidably and rotatably mounted on the main shaft. A burr generating portion is provided at the upper end or lower end of the bearing hole, and a main shaft contact portion having a diameter smaller than the diameter of the burr generating portion is provided near the center from the burr generating portion. It has an effect of preventing the burr portion from contacting the main shaft.

According to a fifth aspect of the present invention, there is provided a main shaft arranged in the optical axis direction, and a lens holder slidably and rotatably mounted on the main shaft, and the lens holder is formed by molding. Is formed around the burr generating portion at the end of the bearing hole, and a protrusion that is sufficiently higher than the height of the burr generated is provided. When a lens holder is handled or assembled, an external force is applied to the burr It has the function of preventing deformation or falling off.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a partial cross-sectional view schematically showing a main part of an objective lens driving device according to Embodiment 1 of the present invention.

In FIG. 1, the spindle 12 is a spindle holder 1
An approximately cylindrical lens holder 14 is slidably and rotatably mounted on the main shaft 12 arranged in the optical axis direction at a predetermined position of the lens holder 3, and an objective lens (not shown) is mounted on the lens holder 14. It is attached at a predetermined position eccentric from the main shaft 12. The lens holder 14 has an upper end 15 and a lower end 1.
The hole diameter of 6 is set as an appropriate hole diameter as the bearing diameter, and the hole diameter of the central portion 17 is configured to be larger than this. In addition, the contact resistance of the bearing is reduced, and an effect of making the bearing less susceptible to foreign matters and scratches inside the bearing is performed. Normally, the bearing gap of the bearing portion composed of the lens holder 14 and the main shaft 12 is 10 μm or less, but in the present embodiment, the upper end 15 and the lower end 16 of the lens holder 14 have a normal gap (10 μm or less). The center 17 is still about 10 μm apart from the upper end 15 and the lower end 16.
The diameter is enlarged.

Reference numeral 18 denotes a burr portion formed when the lens holder 14 is formed by resin molding. The burr portion 18 is provided on the opposite side (the upper portion) of the main shaft 12 from the insertion side (the lower portion of the lens holder 14). This has the effect of preventing the deformation of the burrs due to insertion and the deterioration of bearing characteristics due to falling off.

In order to increase the diameter of the center portion 17 of the bearing hole from the upper end portion 15 and the lower end portion 16 of the bearing hole, the inventors of the present invention conducted experiments to expand the center of the mold pin for forming the bearing hole. It has been confirmed that the mold can be accurately formed by removing the above-mentioned mold pin from the molded product at an appropriate time during the process of cooling the temperature after filling the synthetic resin during molding with the synthetic resin. I have.

(Embodiment 2) FIG. 2 is a partial sectional view schematically showing a main part of an objective lens driving apparatus according to Embodiment 2 of the present invention.

FIG. 2 is different from FIG. 1 in that the corners of the upper end 20 and the lower end 21 of the lens holder 19 are curved. This has the effect of reducing the contact resistance of the bearing and improving the lubrication characteristics and life.

(Embodiment 3) FIG. 3 is a partial cross-sectional view schematically showing a main part of an objective lens driving apparatus according to Embodiment 3 of the present invention.

FIG. 3 differs from FIG. 2 in that portions corresponding to the upper end portion 20 and the lower end portion 21 of the lens holder 19 in FIG. It is fixed. Thereby, the shape of the lens holder 22 can be simplified, and the molding of the lens holder 22 can be facilitated.

(Embodiment 4) FIG. 4 is a partial sectional view schematically showing a main part of an objective lens driving apparatus according to Embodiment 4 of the present invention.

In FIG. 4, the lens holder 25 is provided with a burr portion 26 at the upper end, a bearing contact portion 27 near the center from the upper end portion, and a bearing contact portion 28 at the lower end portion. The central part 29 is the bearing contact parts 27 and 2
8, the contact with the main shaft 12 is limited to the bearing contact portions 27 and 28, the bearing characteristics of the lens holder formed by integral molding are improved, and the burr portion directly contacts the main shaft. It has the effect of avoiding doing so.

(Embodiment 5) FIG. 5 is a partial cross-sectional view schematically showing a main part of an objective lens driving apparatus according to Embodiment 5 of the present invention. A lens holder 30 includes a burr portion 31, a bearing contact portion 32, In addition to 33, a projection 34 is provided around the burr 31 at the upper end. This has the effect of preventing the burr from being deformed or falling off when the lens holder 30 is handled.

Although the embodiments of the present invention have been specifically described on the assumption that the lens holder is integrally molded, the configuration of the present invention is not limited to the above-described embodiment. Instead, it is also useful when a lens holder is composed of two or more members.

Also, a device other than the objective lens driving device, such as a gear rotatably supported on a fixed main shaft, an arm member rotatably supported on a fixed main shaft, or a shaft rotatably / rotatably supported The present invention can be similarly applied to a bearing device using a similar structure for a bearing fixing portion or the like. In particular, in the above-described embodiment, the magnetic attraction / repulsion between the magnet and the exciting coil is used as the driving source for the rotation, but it goes without saying that the present invention is not limited to this.

[0029]

As described above, according to the present invention, the contact portions with the main shaft are limited at the upper end and the lower end of the lens holder.
In addition, it has a curved surface shape with low contact resistance and limits the position of the burr part or configures a protection part around it so as to eliminate or reduce the influence of molding burr generated on the lens holder. An objective lens driving device including a reliable bearing can be provided at relatively low cost.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a main part of a first embodiment of an objective lens driving device according to the present invention;

FIG. 2 is a partial cross-sectional view of a main part of the second embodiment.

FIG. 3 is a partial sectional view of a main part of the third embodiment;

FIG. 4 is a partial cross-sectional view of a main part of the fourth embodiment.

FIG. 5 is a partial sectional view of a main part of the fifth embodiment.

FIG. 6 is a plan view of a conventional objective lens driving device.

FIG. 7 is a sectional view of the same.

FIG. 8 is a partial sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Main shaft 13 Main shaft holder 14 Lens holder 15 Upper end part 16 Lower end part 17 Central part 18 Burr part 19 Lens holder 20 Upper end part 21 Lower part 22 Lens holder 23 Bearing member 24 Bearing member 25 Lens holder 26 Burr part 27 Bearing contact part 28 Bearing Contact part 29 Central part 30 Lens holder 31 Burr part 32 Bearing contact part 33 Bearing contact part 34 Projection

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Takeo Mitou 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A bearing having a main shaft arranged in an optical axis direction and a lens holder slidably and rotatably mounted on the main shaft. An objective lens driving device in which the diameter of the upper end contact portion and the lower end contact portion is small, and the diameter near the central portion is large. 2. The objective lens driving device according to claim 1, wherein corners of an upper end contact portion and a lower end contact portion of the bearing hole of the lens holder are curved. 3. A main shaft arranged in the direction of the optical axis, and a lens holder slidably and rotatably mounted on the main shaft, the lens holder being formed by molding, and a bearing. An objective lens driving device comprising: a burr generating portion provided at an upper end portion or a lower end portion of the hole; 4. A burr generating portion at one of both end portions of the bearing hole is disposed at an end opposite to the insertion side of the main shaft.
The objective lens driving device as described in the above. 5. A main shaft disposed in an optical axis direction, and a lens holder slidably and rotatably mounted on the main shaft, the lens holder being formed by molding, and a bearing. An objective lens driving device provided with a protruding portion sufficiently higher than the height of the generated burr around the burr generating portion at the end of the hole.