JPH0731367Y2 - Objective lens actuator for optical pickup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an objective lens actuator for tracking and focusing in an optical disk recording / reproducing apparatus, and in particular, the balancer mounting position is stable and the balancer mounting operation is easy. The present invention relates to an objective lens actuator of an optical pickup.

[Prior Art] In an optical disk reproducing device such as a CD player, a laser beam is emitted from an optical pickup to a pit row spirally arranged on the optical disk, and laser light reflected from the optical disk is received by the optical pickup and converted into an electric signal. To do.

Due to the eccentricity of the rotation center of the pit train of the optical disc rotating at high speed, the pit train whirls, and the laser spot is swung in the direction perpendicular to the pit train so as to follow the pit train.

That is, tracking is performed.

Also, due to the deformation of the disc and the tilt of the turntable,
Since the optical disk moves up and down, the laser spot also moves up and down accordingly.

That is, focusing is performed.

The tracking and focusing are performed by moving the objective lens holding member to which the objective lens is fixed.

The driving force of the objective lens holding member is generated by arranging a focusing coil and a tracking coil attached to the objective lens holding member in a magnetic field and applying a current to these coils. In order to make it proportional to, it is necessary to apply a force in the opposite direction to the displacement proportional to the displacement.

This force in the opposite direction is applied by the elastic support disposed between the base and the objective lens holding member.

Since the objective lens holding member is rotated around the main shaft at a high speed, it is necessary to balance around the main shaft.

FIG. 9 shows a state in which a balancer for balancing around the main axis is attached to a conventional objective lens holding member.

As shown in FIGS. 9A and 9B, the balancer mounting recess 2a is provided at the end of the objective lens holding member 2, and the balancer 4 as shown in FIG. 9C is inserted.

Before the balancer 4 is inserted, an adhesive is applied to the balancer mounting recess 2a. When the balancer is mounted, excess adhesive is squeezed out of the through holes provided in the balancer 4.

The through holes provided in the balancer 4 also serve as air vents when the balancer is inserted.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional device, since the through holes for allowing the adhesive to escape are formed in the balancer, the manufacturing cost becomes high.

Further, it is necessary to apply an adhesive to the balancer mounting surface of the objective lens holding member, and a step of wiping off the excess adhesive when it has run out is necessary.

Furthermore, the mounting position of the balancer is not stable due to fluctuations in the amount of adhesive between the balancer and the objective lens holding member,
It was easy for the balance to shift.

The present invention was made in view of the above points,
An object of the invention is to provide an objective lens actuator in which the balancer can be easily mounted and the mounting position is stable.

[Means for Solving the Problem] In the objective lens actuator of the present invention, a groove extending from the entrance of the recess to the bottom is provided on the side surface of the balancer mounting recess of the objective lens holding member, and the intersection of the side surface and the bottom surface of the recess is provided. Is provided with a groove continuous with the groove.

In addition, a through hole that is opened to the outside is provided on the bottom surface of the balancer mounting recess of the objective lens holding member, and a groove that is radially connected to the through hole is provided on the bottom surface of the recess.

[Operation] Since the adhesive between the balancer and the objective lens holding member enters the groove or the through hole provided in the balancer mounting recess of the objective lens holding member, the fitting dimensions of the balancer and the objective lens holding member are press-fitted. The mounting position can be made more accurate.

Further, the adhesive can be injected through the through hole of the objective lens holding member after the balancer is press-fitted, which makes the manufacturing process efficient.

Embodiment An embodiment of the objective lens actuator of the present invention will be described with reference to the drawings.

1 is a plan view of an objective lens actuator according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is a sectional view taken along the line BB in FIG.

U-shaped yokes 6 having an inner yoke 6a and an outer yoke 6b are fixed to the base 1 at positions on both sides of the main shaft 8 with screws or the like. A magnetic circuit is formed by the magnet 7.

The objective lens holding member 2 shown in detail in FIGS. 4 to 6 is molded from a high-performance resin having high dimensional stability and rigidity such as polyphenylene sulfide (PPS) or liquid crystal polymer (LCP), and the bearing 11 is inserted. It is integrally attached by molding.

The main shaft 8 tightly fitted with the bearing 11 is press-fitted and fixed in a hole provided in the base 1 with high precision.

The objective lens 3 is adhered to the objective lens holding member 2 with an adhesive and moves integrally with the objective lens holding member 2.

The holes formed in the upper portions of the elastic supports 5 made of silicon rubber are fitted into the protrusions formed in the objective lens holding member 2.

As shown in FIGS. 2 and 3, the lower portion of the elastic support 5 is inserted and fixed in the hole of the base 1.

The elastic support member 5 has an oval shape in its middle portion, and when the objective lens holding member 2 is displaced in the focusing direction, a restoring force is generated by the compression and extension of the ellipse, and a displacement in the tracking direction is generated. A restoring force is generated by twisting the ellipse.

As shown in FIG. 2, the focusing coil 9 is wound around the coil bobbin of the objective lens holding member 2.

Tracking coils 10, 10 ... are focusing coils 9
And is arranged so that the working portion of the coil conductor is located at the strong magnetic field position of the magnetic circuit.

In response to a signal for detecting the deviation of the laser spot with respect to the optical disc pit row in the disc radial direction and the thickness direction, a current is passed through the tracking coils 10, 10 ... and the focusing coil 9, and the laser spot follows the pit row.

The main axis of the moment of inertia of the objective lens holding member 2 is set to the main axis 8
A balancer 4 is press-fitted into a hole provided in the objective lens holding member 2 so as to match the central axis of the. As shown in FIGS. 4 to 6, a mounting recess 2a for the balancer 4 is formed.
Has a through hole 2b at the center of the bottom and a groove 2 of length l on the side surface.
c and 2c are provided.

The adhesive applied to the surface of the recess 2a enters the through hole 2b or the grooves 2c, 2c when the balancer is inserted.

FIG. 7 shows a recess for mounting the balancer 4 of the objective lens holding member 2 of another embodiment. Grooves 2c, 2c reaching the bottom surface are provided on the side surface of the recess, and the corners (A in the figure) of the recess are provided. Is provided so that the groove 2e as shown in FIG. 8 (a) is continuous with the grooves 2c, 2c.

In addition, a through hole 2b is provided on the bottom surface of the recess, and further, a groove 2d that radially extends from the through hole 2b is provided.
Examples of cross-sectional shapes of the groove 2d are shown in FIGS. In this embodiment, the balancer 4 can be bonded by injecting an adhesive from the through hole 2b or the groove 2c after press-fitting the balancer 4 into the recess 2a of the objective lens holding member 2. At that time, the adhesive spreads through the through holes 2b and the radial grooves 2d or through the grooves 2c and 2e to the bottom surface of the recess 2a.

[Advantage of the Invention] As described above, in the objective lens holding member of the present invention, the extra adhesive at the time of mounting the balancer enters the groove or the through hole, so that the mounting position of the balancer is stable and the operation is stable.

If the adhesive is injected from the through hole after the balancer is press-fitted into the recess, the work of mounting the balancer becomes easy.

[Brief description of drawings]

FIG. 1 is a plan view of an objective lens actuator according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a sectional view taken along line BB in FIG. 1, and FIG. FIG. 5 is a top view showing the lens holding member, FIG.
FIG. 7 is a sectional view taken along the line AA in FIG. 4, and FIG. 7 is a perspective view showing a balancer mounted state in another embodiment of the present invention,
FIG. 8 (a) is a sectional view showing a portion A in FIG.
FIGS. 9 (b), 9 (c) and 9 (d) are sectional views showing a portion B in FIG. 7, FIG. 9 (a) is a plan view showing a balancer mounting portion of a conventional objective lens holding member, and FIG. 9B is a sectional view taken along the line AA in FIG. 9, and FIG. 9C is a perspective view showing a balancer attached to a conventional objective lens holding member. 1 ... Base, 2 ... Objective lens holding member, 2a ... Recess, 2b ... Through hole, 2c ... Groove, 3 ... Objective lens, 4 ...
Balancer, 5 ... Elastic support, 6 ... Yoke, 6a ...
Inner yoke, 6b ... Outer yoke, 7 ... Permanent magnet, 8 ... Main shaft, 9 ... Focusing coil, 10 ... Tracking coil, 11 ... Bearing.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-63-157329 (JP, A) JP-A-60-147923 (JP, A) Noboru Koma "Handbook for Machinery and Equipment Design" February 10, 1964 Published by Taikaku, P. 154 Figures 513 and 514

Claims (2)

[Scope of utility model registration request] 1. A groove extending from the entrance to the bottom of the recess is provided on the side surface of the balancer mounting recess of the objective lens holding member, and a groove continuous with the groove is provided at the intersection of the side surface and the bottom of the recess. Objective lens actuator for optical pickup. 2. A light which is characterized in that a through hole which is opened to the outside is provided on the bottom surface of the balancer mounting recess of the objective lens holding member, and a groove which is connected to the through hole and is radially arranged is provided on the bottom surface of the recess. Objective lens actuator for pickup.