JPH0728584Y2 - 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, tracking and focusing operations are accurately performed and manufacturing is easy. The present invention relates to an objective lens actuator for 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.

Conventionally, holes provided in the elastic support 5 as shown in FIG.
5a was fitted to the projection 2a of the objective lens holding member 2 shown in FIG. 11, and the upper portion of the elastic support 5 was attached to the objective lens holding member.

The lower end of the elastic support is inserted and fixed in the hole provided in the base.

The thickness l ₁ of the elastic support 5 shown in FIG. 10 is generally set so that the fitting portion of the elastic support does not ride on the flange of the projection so that the projection of the objective lens holding member 2 shown in FIG.
It is made smaller than the length l ₂ to the flange of 2a.

[Problems to be Solved by the Invention] When the elastic support body is attached to the objective lens holding member, the above-mentioned conventional one cannot accurately determine the attachment position.

Therefore, the left and right balance of the elastic support is easily lost, and the stationary position in the tracking direction varies, which may cause an offset in the tracking control and make the operation unstable.

Further, after attaching the elastic support to the objective lens holding member, it was necessary to reinforce with an adhesive.

The present invention was made in view of the above points,
It is an object of the invention to provide an objective lens actuator that does not cause an offset in tracking control and has stable operation.

Another object of the present invention is to provide an objective lens actuator which does not need to be reinforced with an adhesive after the elastic support is attached to the objective lens holding member.

[Means for Solving the Problems] In the objective lens actuator of the present invention, an elastic support body is arranged between the objective lens holding member and the base, and the restoring force of the elastic support body is applied to the displacement of the objective lens holding member. In an objective lens actuator of an optical pickup configured to be added to a holding member, a convex portion or a concave portion is provided on a surface of a projection portion that fits into a hole of an elastic support body provided in the objective lens holding member, A concave portion or a convex portion that engages with the convex portion or the concave portion of the protrusion is provided on the inner surface of the hole that fits with the protrusion.

Further, in the objective lens actuator, a projection portion that fits into the hole of the elastic support body is provided at a position sandwiching the objective lens of the objective lens holding member, and the elastic support body is arranged over each projection portion and the base. is there.

[Operation] According to the present invention, since the hole of the elastic support and the surface of the projection of the objective lens holding member have projections and depressions that engage with each other, when the elastic support is attached to the objective lens holding member, the mounting position is accurately adjusted. The elastic support is balanced on the left and right to stabilize the stationary position in the tracking direction.

Therefore, the tracking control does not generate an offset and the operation is stable.

Further, since the elastic support does not shift with respect to the protrusion, it is not necessary to reinforce with the adhesive after the elastic support is attached to the objective lens holding member.

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.
The figure is a sectional view taken along line BB in FIG.

In the figure, parts having the same functions as those shown in the conventional example are designated by the same reference numerals.

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 made of polyphenylene sulfide (PPS) or liquid crystal polymer (L
It is molded from a high-performance resin such as CP) having high dimensional stability and rigidity, and the bearing 11 is integrally attached by insert 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.

The protrusion 2a shown in FIG. 4A is shown in FIGS. 7 (a) and 7 (b).
As shown in FIG. 3, a recess is provided around the surface.

The holes formed on the upper portions of the elastic supports 5 and 5 made of silicon rubber are fitted into the protrusions 2a formed on the objective lens holding member 2, and the recesses of the protrusions 2a are formed on the inner surface of the holes. Is provided with a convex portion that engages with, and the mounting position of the elastic supports 5, 5 with respect to the objective lens holding member 2 is accurately determined.

The recesses of the protrusion 2a may be provided only at the top and bottom as shown in FIGS. 8 (a) and 8 (b).

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.

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.

The focusing coil 9 is wound around the bobbin of the objective lens holding member 2 in an aligned manner, and the tracking coil 10 is attached to the outside of the focusing coil 9 so that the acting 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.

Although the embodiment is configured as described above, the invention is not limited to this. For example, a projection may be provided on the projection 2a of the objective lens holding member 2 and a recess may be provided in the hole of the elastic support 4.

[Advantage of the Invention] According to the objective lens actuator of the present invention, when the elastic support body is attached to the objective lens holding member, the holes of the elastic support body and the projection surface of the objective lens holding member have irregularities that engage with each other. Since the mounting position can be accurately determined and the elastic support does not shift with respect to the protrusion, offset does not occur in tracking control and operation is stable. Further, after the elastic support is attached to the objective lens holding member, it is not necessary to reinforce with the adhesive, and it is possible to obtain the effect of reducing the number of assembling steps.

Further, in the case where the projection of the objective lens holding member that fits into the hole of the elastic support body is provided at a position sandwiching the objective lens, the elastic support body is balanced left and right to stabilize the stationary position in the tracking direction and perform tracking control. The operation in is more stable.

[Brief description of 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.
1 is a sectional view taken along the line BB in FIG. 1, FIG. 4 is a top view showing the objective lens holding member of the same embodiment, and FIG. 5 is a bottom view of the same.
FIG. 6 is a sectional view of the same, and FIG. 7 (a) is a plan view showing a projection of an objective lens holding member in an embodiment of the present invention.
8B is a front view, FIG. 8A is a plan view showing a projection of an objective lens holding member in another embodiment of the present invention, and FIG. 8B is the same front view. Is a front view showing a conventional elastic support, FIG. 10 is a side view of the same, FIG. 11 (a) is a plan view showing a projection of a conventional objective lens holding member, and FIG. 11 (b) is a front view of the same. Is. 1 ... Base, 2 ... Objective lens holding member, 2a ... Protrusion, 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.

Claims (2)

[Scope of utility model registration request] 1. An optical pickup configured to arrange an elastic support member between an objective lens holding member and a base, and to apply a restoring force of the elastic support member to the objective lens holding member with respect to displacement of the objective lens holding member. In the objective lens actuator, a convex portion or a concave portion is provided on the surface of the projection portion that fits into the hole of the elastic support body provided in the objective lens holding member, and the projection is formed on the inner surface of the hole that fits into the projection portion of the elastic support body. An objective lens actuator for an optical pickup, wherein a concave portion or a convex portion that engages with a convex portion or a concave portion of the portion is provided. 2. A protrusion according to claim 1, wherein the protrusion is fitted into the hole of the elastic support, and the elastic support is disposed between the protrusion and the base. Objective lens actuator for optical pickup.