JPH05234113A - Focus actuator for optical disk device - Google Patents

Abstract

PURPOSE:To completely cut off dust entering the inside of an optical head and to improve the reliability of an optical system on the lens positioner mechanism, so called, the focus actuator of various kinds of an optical disk devices and a magneto-optical disk devices. CONSTITUTION:A lens holder 15-1 is inserted into a through hole 16-1a so that a coil 15-2 provided on the outer peripheral surface of the lens holder 15-1 attaching an objective 4-3 to one end side in parallel with each other and a permanent magnet 16-2 arranged in the recessed part of a focus base 16-1 consisting of magnetic material are faced each other at a fixed interval. This device is constituted so that both end edges of the lens holder 15-1 and both surfaces of the outer peripheral part of the focus base 16-1 are coupled with two sheets of leaf springs 17 and the objective 4-3 of the lens holder 15-1 follows up an optical disk rotating at a fixed interval by applying current through the coil 15-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called focus actuator, which is a lens positioner mechanism for various optical disk devices and magneto-optical disk devices.

Conventionally, it has been said that the optical disk device and the magneto-optical disk device are strong against dust, but recently, in the optical disk device, the number of failures caused by dust increases,
In order to remove the attached dust, a medium cleaner and a lens cleaner for wiping off dust and dust adhering to the lens are currently distributed to the user and used as countermeasures.

However, optical components such as a galvanometer mirror are provided inside the optical head, and most of the dust adhering to the back surface of the optical components and the objective lens (on the side opposite to the optical disk medium) is actually cleaned. However, the focus actuator that can prevent the intrusion of dust into the optical head is required because the reliability of the optical disk device is deteriorated.

[0004]

2. Description of the Related Art As shown in FIG. 5, a focus actuator which has been widely used in the past is a lens holder 4-1 having an objective lens 4-3 adhered to the side facing the optical disk, which is composed of a strip-shaped thin plate on one side surface. One end of each spring 4-6 is fixed in parallel, and the other end is fastened to the focus base 4-4 with a pair of base stoppers 4-5. Holder 4-1 is connected so that it can swing in parallel.

Coil 4-2 is adhered to both side surfaces of the two springs 4-6 fixed to the side surfaces which are adjacent and opposed to each other. When a current is applied to the coil 4-2, the yoke 4-7b is opened. The lens holder 4-1 by the magnetic circuit with the permanent magnet 4-7a
That is, the objective lens 4-3 is configured to swing vertically with respect to the optical disc 1.

The focus actuator 4
As shown in FIG. 7, the optical head mounted with is mounted with the focus base 4-4 of the focus actuator 4 together with the base stopper 4-5 on the optical disc 1 side of the case body 2-1 in which the optical system 3 is installed. Then, the permanent magnet 4-7a having the yoke 4-7b is similarly fixed to the case body 2-1 at a position facing the coil 4-2 of the lens holder 4-1 at a minute interval,
A lid 2-2 having a hole through which the laser optical axis 6 passes between the focus actuator 4 and the optical disc 1 is fastened to the case body 2-1.

Further, as shown in FIG. 6, a mirror holder 5-holding a galvano mirror 5-2 having a 45 ° surface of a right-angled triangular prism as a reflecting surface is provided below the focus actuator 4.
1 and the tracking base 5-3 are connected by a spring 5-5 consisting of a strip of thin plate, and a coil 4-2 is adhered to each side of the mirror holder 5-1 and a yoke 5-6b is provided. The galvano mirror 5-2 is formed by the magnetic circuit with the magnet 5-6a.
As shown in FIG. 7, the tracking actuator 5 configured so that the reflection surface of the optical axis rotates with respect to the tracking base 5-3 has the laser optical axis 6 of the optical system 3 galvano mirror 5-2.
The objective lens 4-3 of the focus actuator 4 is arranged so as to be refracted at substantially the center thereof.

[0008]

A problem with the conventional optical head described above is that the lid is fastened between the focus actuator 4 and the optical disc 1 as shown in FIG.
The dust enters the inside of the case body 2-1 through the gap formed between the hole 2-2 through which the laser optical axis 6 passes and the lens holder 4-1 of the focus actuator 4, and the objective lens
Dust adheres to the rear surface of 4-3, that is, the surface on the incident side of the laser optical axis 6 and the surface of optical components such as the galvano mirror 5-2,
Due to the deterioration of each function, the reliability of the optical disk device is deteriorated. However, it is almost impossible to clean the dust adhering to it from the outside of the case body 2-1, and the whole mounting must be disassembled and cleaned.

In view of the above problems, it is an object of the present invention to provide a lens actuator which has a simple structure and can completely block dust invading the inside of an optical head to improve the reliability of an optical system. And

[0010]

According to the present invention, as shown in FIG. 1, a lens holder 15 having an objective lens 4-3 fixed to one end side thereof is provided.
-1 through the through hole 16 so that the coil 15-2 provided parallel to each other on the outer peripheral surface and the permanent magnet 16-2 provided in the recess of the focus base 16-1 made of a magnetic material face each other at a constant interval. -1a, insert the lens holder 15-1 into the lens holder 15-1
Both end edges of the focus base 16-1 and the outer peripheral surface of the focus base 16-1 are coupled by two leaf springs 17, and a current is applied to the coil 15-2 to apply the current to the objective lens 4-of the lens holder 15-1. 3
The optical disc is configured so that it can follow the rotating optical disc at regular intervals.

[0011]

The focus actuator 14 of the present invention comprises a pair of coils 15-2 arranged on the outer peripheral surface of a lens holder 15-1 having an objective lens 4-3 fixed to one end side and a permanent base arranged on a focus base 16-1. Since both ends of the lens holder 15-1 and the outer peripheral portion of the focus base 16-1 are connected by two leaf springs 17 so that the magnet 16-2 and the magnet 16-2 face each other at a constant interval,
By molding the focus base 16-1 with a magnetic material, the permanent magnet 16-2 can serve as a yoke and a magnetic field shield.

Further, the focus actuator 14 is fastened to the upper opening formed in the case body 12-1 of the optical head as shown in FIG. 4, so that the opening is formed by the focus base 16-1 and the lens holder 15. -1, The objective lens 4-3 and the leaf spring 17 are completely sealed, so that the dust that enters the inside of the optical head can be completely blocked, and the reliability of the optical system can be improved. ..

[0013]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 is a side sectional view showing a focus actuator according to an embodiment of the present invention, FIG. 2 is a perspective view showing the focus actuator of this embodiment, FIG. 3 is a perspective view showing a focus base portion of this embodiment, and FIG. A side sectional view of an optical head equipped with the focus actuator of the present embodiment is shown, and the same members as those in FIGS. 5 to 7 are designated by the same reference numerals.

The focus actuator 14 of the present invention is
As shown in FIG. 4, a lens holder part 15 that holds the objective lens 4-3 and oscillates slightly in the vertical direction with respect to the facing optical disk 1 and a magnetic circuit for driving the lens holder part 15 are formed and a case is formed. The main body 12-1 includes a focus base portion 16 that is fastened to the upper portion, and two leaf springs 17 that connect the focus base portion 16 and the lens holder portion 15.

As shown in FIG. 1, the lens holder portion 15 is formed, for example, in a cylindrical step so that it can be connected to two leaf springs 17, which will be described later, at both end edges thereof, and allows the laser beam to pass on its center line. The optical axis hole 15-1a is bored, and the coil 15-2
An objective lens 4-3 for focusing the laser light (not shown) on the surface of the optical disc 1 is formed on the lens holder 15-1 formed so that the bonding surface of the optical disc is parallel to the large diameter portion of the outer circumference. A coil 15-2, which is fixed to one end side of 15-1a and swings the objective lens 4-3 toward the optical disc 1, is adhered to parallel surfaces on the outer circumference of a large diameter.

As shown in FIG. 3, the focus base portion 16 is provided with a through hole 16-1a for inserting and swinging the lens holder portion 15 in the central portion of a quadrangular magnetic material plate. A coil 15-2 of the lens holder portion 15 is attached to a focus base 16-1 in which a rectangular column-shaped positioning post 16-1b is projected at each corner and a square recess is formed inside the positioning post 16-1b. And a pair of permanent magnets 16-2 respectively forming a magnetic circuit are opposed to each other so that the bottom surfaces of the respective recesses have polarities different from each other and have the same polarity across the through hole 16-1a.

As shown in FIG. 2, the leaf spring 17 is formed by cutting a thin metal plate having elasticity, for example, a phosphor bronze plate for spring into a rectangular shape so as to have the same size as the outer shape of the focus base portion 16 and arranging it at each corner. A notch having the same size as that of the positioning post 16-1b is formed, and the lens holder as shown in FIG.
Holes are provided at both ends of 15-1 so that they can be fitted into the stepped portions.

In the focus actuator 14 using the above members, as shown in FIG. 1, the coils 15-2 provided in parallel to each other on the outer peripheral surface of the lens holder 15-1 have a focus base 16.
The lens holder portion 15 is positioned with respect to the focus actuator 14 so as to face the permanent magnet 16-2 disposed in the concave portion of -1 at a constant interval.

Then, the holes formed in the central portions of the two leaf springs 17 are fitted into the stepped portions formed on both end edges of the lens holder 15-1 and are joined by the stop rings 14-2,
The notch formed at each corner of the leaf spring 17 is fitted into the positioning post 16-1b of the focus base portion 16 and coupled by the base stopper 14-1 to apply a current to the coil 15-2 so that the lens is formed. The objective lens 4-3 of the holder 15 is configured to follow the rotating optical disc at a constant interval.

The optical head equipped with the focus actuator 14 has the focus base portion 16 of the focus actuator 14 above the optical disk 1 side of the case body 12-1 in which the optical system 3 is installed as shown in FIG. The same tracking actuator 5 as the conventional one is arranged so that it is fastened together with the base stopper 14-1 and the reflecting surface of the galvano mirror 5-2 is located under the objective lens 4-3 of the focus actuator 14. There is.

As a result, the upper part of the case body 12-1, that is, the opening on the side of the optical disc 1 is provided with the lens holder portion 15 of the focus actuator 14, the leaf spring 17, and the focus base portion.
Since it is completely sealed by 16, it is possible to completely block the dust that enters the inside of the optical head and improve the reliability of the optical system.

The above description is based on the illustrated embodiment, but the present invention is not limited to the embodiment described above.
For example, the leaf spring 17 may be formed of a synthetic resin thin plate having elasticity capable of following the optical disc at a constant interval,
It is not limited to the metal thin plate.

[0023]

As is apparent from the above description, according to the present invention, the reliability of the optical system for recording / reproducing information by completely blocking the dust invading the inside of the optical head with a very simple structure can be obtained. It is possible to provide a focus actuator for an optical disk device, which has advantages such as improvement, and which can be expected to have a remarkable economic effect and reliability improvement effect.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a focus actuator according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a focus actuator of this embodiment.

FIG. 3 is a perspective view showing a focus base portion of the present embodiment.

FIG. 4 is a side sectional view showing an optical head equipped with the focus actuator of this embodiment.

FIG. 5 is a perspective view showing a conventional focus actuator.

FIG. 6 is a perspective view showing a tracking actuator.

FIG. 7 is a side sectional view showing a conventional optical head.

[Explanation of symbols]

1 is an optical disk, 3 is an optical system, 4-3 is an objective lens, 5 is a tracking actuator, 5-1 is a mirror holder, 5-2 is a galvanometer mirror, 5-3 is a tracking base, 5-5 is a spring, and 6 is Laser optical axis, 12-1 case body, 14 focus actuator, 14-1 base stopper, 14-2 stop ring, 15 lens holder part, 15-1 lens holder, 15-1a optical axis Hole, 15-2 coil, 16 focus base part, 16-1 focus base, 16-1a through hole, 16-1b positioning post, 16-2 permanent magnet, 17 leaf spring,

Claims (2)

[Claims] 1. A coil (15-2) provided parallel to each other on an outer peripheral surface of a lens holder (15-1) having an objective lens (4-3) fixed to one end side, and a focus base (16-1). Through holes so that the permanent magnets (16-2) placed in the recesses face each other at regular intervals.
Insert the lens holder (15-1) into the (16-1a), and the both ends of the lens holder (15-1) and the focus base (16-1).
The outer peripheral part of both sides of the objective lens (4-3) of the lens holder (15-1) is connected by applying a current to the coil (15-2) by connecting both sides with two leaf springs (17). A focus actuator for an optical disk device, which is configured to follow a rotating optical disk at a constant interval. 2. The focus actuator for an optical disk device according to claim 1, wherein the focus base (16-1) is made of a magnetic material so as to serve as a yoke and a magnetic field shield.