JPH08138254A - Objective lens driving device for optical pickup - Google Patents

Abstract

PURPOSE: To attain superior reliability and low power consumption of the device used for an optical disk device such as a CD player and an LD player. CONSTITUTION: A small-sized objective lens 104 is fixed by a cover 11 having a light transmitting hole smaller than the small-sized objective lens 104 in diameter, and this cover 11 and an objective lens holder 9 are fixedly stuck to each other by adhesion, etc. By this method, deterioration of optical characteristics of the small-sized objective lens 104 due to adhesion is eliminated, and an edge of an outer circumference of the small-sized objective lens 104 can be miniaturized, thus attaining superior reliability and low power consumption of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc reproducing apparatus such as a CD (compact disc) player or an LD (laser disc) player, or an objective lens driving apparatus for an optical pickup used in an optical disc recording / reproducing apparatus.

[0002]

2. Description of the Related Art FIG. 8 is a schematic view of the structure of an optical pickup installed in an optical disk device.

A beam emitted from the semiconductor laser 1 passes through a beam splitter 2 and enters an objective lens 4 provided in a lens holder 3. Then, the laser light is focused by the objective lens 4, and a minute beam spot is formed on the recording surface of the optical disc E. The lens holder 3 is provided with a driving unit 5 which is composed of a piezoelectric element and an electromagnetic circuit and can drive the objective lens 4 in the focus direction and the tracking direction. The objective lens 4 can follow the surface shake and eccentricity of the optical disc E. It is like this.

The beam reflected from the recording surface of the optical disk E passes through the objective lens 4 and returns, and is reflected by the beam splitter 2 in the direction perpendicular thereto. Then, according to the intensity of the beam detected by the pin photodiode 6,
The information pits of the optical disc E can be read.

Since the objective lens driving device equipped with the objective lens 4 follows the disk E rotating at a high speed, the objective lens 4 may be momentarily subjected to a gravitational acceleration of 100 m / s ² . In addition to this, a considerable force is expected to be applied to the objective lens under various environments, and the fixing structure of the objective lens 4 is required to have sufficient strength and reliability.

In the past, glass having high mechanical strength was mainly used as the material for the objective lens 4, but in recent years, for example, acrylic plastics have been used mainly for the purpose of cost reduction. In order to secure the mechanical strength and reliability, it is necessary to devise a bonding method such as providing a huge edge (a peripheral ring wall outside the effective diameter of the objective lens) on the outer periphery of the objective lens 4.

FIG. 7 is a side sectional view of the internal structure of a holder of a conventional objective lens driving device for an optical pickup.

The objective lens 4 is housed in the lens holder 3. The objective lens 4 is integrally formed of plastic, and its upper surface 4a and lower surface 4b are spherical or aspherical convex curved surfaces. And there is an edge 4 on the outer circumference of the spherical surface.
c is formed, and a lens positioning wall 4d is formed in a lower portion of the edge 4c with a step.

The lens holder 3 has an aperture 3a in its inner diameter portion for narrowing the incident beam to the effective diameter of the objective lens 4.
Is provided. Due to the existence of the step 3c, the aperture 3a is formed with a hole diameter D smaller than that of the lower end hole 3b. The beam transmitted through the beam splitter 2 shown in FIG. 8 is focused by an aperture into a beam having a diameter D, and the beam having the diameter D is made incident on the effective diameter of the objective lens 4.

Further, in the conventional objective lens holder 3,
An outer wall 7 is circumferentially formed on the upper portion of the aperture 3a. The position of the objective lens 4 is determined by the inner peripheral portion of the outer wall 7 and the lens positioning wall 4d, and the outer peripheral portion of the outer wall 7 and the outer peripheral portion of the edge of the objective lens 4 are fixed by an adhesive 8.

[0011]

However, in the above conventional structure, the adhesive 8 causes stress in the edge 4c,
This stress causes a problem that the objective lens 4 is distorted and the optical characteristics are deteriorated.

Further, it is necessary to make the edge 4c large so that the objective lens 4 is not distorted. Therefore, the objective lens 4 becomes large and the lens holder 3 becomes large,
There is a problem that the power consumption of the objective lens actuator increases.

An object of the present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide an objective lens driving device for an optical pickup which is excellent in reliability and consumes less power.

[0014]

In order to achieve this object, an objective lens driving device for an optical pickup according to the present invention fixes an objective lens with a cover having a light transmission hole smaller than the diameter of the objective lens. The objective lens holder is fixed.

[0015]

According to the present invention, since the objective lens is not directly adhered by the above structure, the distortion of the objective lens due to the adhesive is eliminated and the reliability is improved. Further, since the edge for distortion prevention can be made small and the objective lens can be made compact and lightweight, the power consumption of the objective lens driving device for the optical pickup can be reduced.

[0016]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a side sectional view of an objective lens driving device for an optical pickup according to the first embodiment of the present invention.
It should be noted that constituent members having the same functions as those of the conventional example shown in FIGS. 7 and 8 are denoted by the same reference numerals.

Reference numeral 9 is an objective lens holder. The objective lens holder 9 is arranged at the tip of the beam splitter 2 in the optical pickup of the optical disc device shown in FIG. Further, the small objective lens 104 supported in the objective lens holder 9 is the beam splitter 2
This is for converging the beam that has passed through to form a minute spot of the beam on the recording surface of the optical disc E.

The small objective lens 104 has a convex shape whose upper and lower surfaces are spherical or aspherical, and has a flat edge 1 around it.
0 is formed.

The objective lens holder 9 has a hole 9a formed at the center, and its upper portion projects in the inner diameter direction.
An aperture 3a is formed by the inner surface thereof. The beam radiated into the objective lens holder 9 is focused by the aperture 3a into a light beam having a diameter D.

Inside the objective lens holder 9, an upper hole 9c extending from the upper end of the aperture 3a in the radial outer peripheral direction is formed, and from the upper end of the upper hole 9c extending in the radial outer peripheral direction, the diameter is substantially equal to the diameter of the small objective lens 104. An insertion hole 9d is formed. The insertion hole 9d and the small objective lens 10
The small objective lens 104 is positioned by the plane edge 10 of 4.

Reference numeral 11 denotes a cover, which is adhered to the objective lens holder 9. A light transmission hole 12 is formed in the center of the cover 11.
Are formed. The hole diameter is smaller than the diameter of the small objective lens 104, and the converged light emitted from the small objective lens 104 is not blocked.

Reference numeral 13 denotes a damper, which is adhered to the upper surface of the cover 11 and prevents the optical disc E from being scratched when the objective lens driving device collides with the optical disc E.

Reference numeral 5 is a driving means composed of an electromagnetic circuit or a piezoelectric element, and drives the objective lens holder 9 including the small objective lens 104 in the focus direction and the tracking direction.

Next, a method of positioning and fixing the small objective lens 104 with respect to the objective lens holder 9 will be described.

The outer peripheral surface and the lower surface of the flat edge 10 of the small objective lens 104 are brought into contact with the side surface of the insertion hole 9d of the objective lens holder 9 and the step portion to be positioned. And cover 11
The lower surface of the is pressed against the upper surface of the flat edge 10, and in this state, the cover 11 and the objective lens holder 9 are adhered to each other to fix the small objective lens 104.

As described above, in the objective lens driving device for the optical pickup according to the present embodiment, the objective lens 104 is inserted into the insertion hole 9d in the upper part of the objective lens holder 9, and the light smaller than the outer diameter of the small objective lens 104 is used. Since the cover 11 having the transmission hole 12 presses the upper surface of the flat edge 10 and the cover 11 is fixedly adhered to the objective lens holder 9, the small objective lens 104 is not directly adhered to the small objective lens 104. Can be prevented. Further, since the edge of the objective lens 104 for preventing the occurrence of distortion can be reduced, it is possible to reduce the size and weight of the objective lens.

The second embodiment of the present invention will be described below with reference to the drawings. 2 is a perspective view of an essential part of an objective lens driving device for an optical pickup according to a second embodiment of the present invention, and FIG. 3 is a side sectional view of the same device.

The conventional example shown in FIGS. 7 and 8 and FIG.
The same reference numerals are given to constituent members having the same function as.

The difference from the configuration of FIG. 1 is that a convex portion 109 is formed on the side surface.
an objective lens holder 109 with a convex portion formed with a,
A notched cover 110 having a side wall 110a and a notched portion 110b formed in the side wall is provided, and the notched portion 110b and the convex portion 109a are used to position the notched cover 110. That is the point.

Next, the objective lens holder 109 with a convex portion
A method of positioning and fixing the small objective lens 104 with respect to will be described.

The outer peripheral surface and the lower surface of the planar edge 10 of the small objective lens 104 are brought into contact with the side surface of the insertion hole 9d of the convex objective lens holder 109 and the step portion to be positioned. Then, the notched cover 110 is positioned by the notch 110b and the convex portion 109a, and the lower surface of the notched cover 110 is brought into pressure contact with the upper surface of the flat edge 10. Then, the side wall 110a of the notched cover and the objective lens holder 109 are adhered to each other to fix the small objective lens 104.

As described above, the objective lens driving device for the optical pickup according to the present embodiment has the convex portion 109a on the side surface.
The objective lens holder 109 with a convex portion is formed, and the cover 110 with a notch having the notch 110b formed on the side wall 110a is provided.
With the configuration in which the notched cover 110 is positioned by the convex portion 109a and the convex portion 109a, the notched cover 11
When 0, the force of pressing the small objective lens 104 is constant,
Since the stress distortion does not occur in the small objective lens 104, in addition to the effect of the first embodiment, the small objective lens 104
The fixing accuracy of is improved.

The third embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a perspective view of an essential part of an objective lens driving device for an optical pickup according to a third embodiment of the present invention, and FIG. 5 is a side sectional view.

The conventional example shown in FIGS. 7 and 8 and FIG.
The same reference numerals are given to constituent members having the same function as.

The difference from the configuration of FIG. 1 is that the objective lens holder 2 with a protrusion having a plurality of protrusions 209a formed on the upper portion thereof.
09 and a holed cover 2 in which a plurality of positioning holes 210a are formed so that their positions match those of the protrusions 209a.
10 is provided.

Next, the objective lens holder 209 with a projection is provided.
A method of positioning and fixing the small objective lens 104 with respect to will be described.

The outer peripheral surface and the lower surface of the planar edge 10 of the small-sized objective lens 104 are brought into contact with the side surface of the insertion hole 9d of the objective lens holder with projection 209 and the step portion to be positioned. Then, the holed cover 210 is positioned by the protrusion 209a and the positioning hole 210a, and the lower surface of the holed cover 210 is pressed against the upper surface of the flat edge 10. And the protrusion 209
The cover 210 with holes is fixed by heat-sealing a,
The objective lens 104 is fixed.

As described above, in the objective lens driving device for the optical pickup according to the present embodiment, the objective lens holder 20 with protrusions having the plurality of protrusions 209a formed on the upper portion thereof is provided.
9 and a cover 210 with a hole in which a plurality of positioning holes 210a are formed. The positioning holes 210a are inserted into these protrusions 209a and fixed by heat fusion, and the small objective lens 104 is fixed to bond them. In addition to the effect of the first embodiment, the reliability of fixing the small objective lens 104 against environmental changes such as high temperature and high humidity is improved.

The fourth embodiment of the present invention will be described below with reference to the drawings. FIG. 6 is a side sectional view of an objective lens driving device for an optical pickup according to a fourth embodiment of the present invention.

The conventional example shown in FIGS. 7 and 8 and FIG.
The same reference numerals are given to constituent members having the same function as.

The difference from the configuration of FIG. 1 is that a lens cover 310 made of an elastic member and integrally formed with a collision prevention wall 310a for preventing a lens collision and a disk collision is bonded to the upper portion of the objective lens holder 309. The point is that the small objective lens 104 is fixed by the method described above.

Since the method of fixing the small objective lens 104 is the same as in the first to third embodiments, it will be omitted here.

As described above, the objective lens driving device for the optical pickup according to this embodiment is made of an elastic member,
The collision prevention wall 310a is formed integrally with the lens cover 31.
By fixing 0 to the upper part of the objective lens holder 309 by a method such as adhesion and fixing the small objective lens 104, the collision preventing material (for example, the damper 13 in FIG. 1) can be eliminated,
In addition to the effects of the first embodiment, it is possible to reduce the cost by reducing the number of parts.

[0045]

As described above, according to the present invention, the objective lens holder having at least the insertion hole for inserting the objective lens and the light transmitting hole having a diameter smaller than that of the objective lens are fixed to the upper surface of the objective lens holder. Consisting of a cover,
By fixing the objective lens by bringing the objective lens into contact with the cover, the objective lens is not directly bonded. Therefore, the distortion of the objective lens due to the adhesive is eliminated, and not only the reliability is improved, but also the edge for preventing the distortion can be made small, and the objective lens can be made compact and lightweight. Can be realized.

[Brief description of drawings]

FIG. 1 is a side sectional view of an objective lens driving device for an optical pickup according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part of an objective lens driving device for an optical pickup according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of an objective lens driving device for an optical pickup according to a second embodiment of the present invention.

FIG. 4 is a perspective view of a main part of an objective lens driving device for an optical pickup according to a third embodiment of the present invention.

FIG. 5 is a side sectional view of an objective lens driving device for an optical pickup according to a third embodiment of the present invention.

FIG. 6 is a side sectional view of an objective lens driving device for an optical pickup according to a fourth embodiment of the present invention.

FIG. 7 is a side sectional view of a holder of a conventional objective lens driving device for an optical pickup.

FIG. 8 is a schematic diagram of a structure of a conventional optical pickup.

[Explanation of symbols]

 9 Objective Lens Holder 9a Hole 9c Upper Hole 9d Insertion Hole 10 Flat Edge 11 Cover 12 Light Transmission Hole 13 Damper 104 Small Objective Lens

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomonada Kamei 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (9)

[Claims] 1. At least an objective lens, and an objective lens holder having an insertion hole for inserting the objective lens,
The cover has a light transmission hole having a diameter smaller than that of the objective lens and is fixed to the upper surface of the objective lens holder, and a driving unit for driving the objective lens holder in the focus direction or the tracking direction. An objective lens driving device for an optical pickup, wherein the objective lens is brought into contact with an objective lens holder and the objective lens is fixed. 2. A cover comprising at least a side wall having a concave portion or a hole portion on a side surface and an objective lens holder having a convex portion formed on a side surface, and the concave portion or the hole portion of the cover and the objective lens holder. The objective lens driving device for an optical pickup according to claim 1, wherein the positioning is performed with the convex portion. 3. A cover having at least a side wall having a convex portion on a side surface and an objective lens holder having a concave portion or a hole portion on a side surface, wherein the convex portion of the cover and the concave portion of the objective lens holder are provided. The objective lens driving device for an optical pickup according to claim 1, wherein the positioning is performed with the hole. 4. A cover having at least a convex portion formed on the same plane as a light transmitting hole, and an objective lens holder having a concave portion or a hole portion formed on the upper surface in alignment with the convex portion. The objective lens driving device for an optical pickup according to claim 1, wherein positioning is performed by the convex portion of the optical pickup and the concave portion or the hole portion of the objective lens holder. 5. A cover having at least a recess or a hole formed on the same plane as the light transmitting hole, and an objective lens holder having a projection on the upper surface aligned with the recess or the hole. The objective lens driving device for an optical pickup according to claim 1, wherein positioning is performed by a concave portion or a hole portion of the cover and a convex portion of the objective lens holder. 6. The objective lens driving device for an optical pickup according to claim 1, wherein the objective lens holder and the cover are fixed by heat fusion. 7. An objective lens holder having a projection on at least an upper surface or a side surface and a cover having a hole or a notch at a position corresponding to the projection, and the projection is fixed by heat fusion. The objective lens driving device for an optical pickup according to claim 1. 8. An objective lens holder having at least an upper surface or a side surface with a hole or a notch, and a cover having a projection at a position corresponding to the hole or the notch,
The objective lens driving device for an optical pickup according to claim 1, wherein the protrusion is fixed by heat fusion. 9. At least an objective lens and a light transmission hole having a diameter smaller than that of the objective lens, and a protrusion for integrally preventing the collision between the optical disc and the objective lens is integrally formed on the upper surface, and the material thereof is an elastic material. A cover composed of, and an objective lens holder having an insertion hole for inserting the objective lens,
Drive means for driving the objective lens holder in the focus direction or the tracking direction, the objective lens is brought into contact with the cover and the objective lens holder, and the cover is fixed to the objective lens holder. Objective lens drive for optical pickup with fixed objective lens.