JPH1079128A - Objective lens actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause a spindle to collide with a supporting piece so as to offset oscillation, by causing the natural oscillation frequency of a collision damper unit including a leaf spring and the spindle to coincide with the oscillation frequency of the supporting piece in a focusing direction. SOLUTION: A collision damper unit 10 is provided to protrude in parallel along a focusing direction with respect to a supporting piece 2b of a body portion 2a. Such collision damper unit 10 includes a leak spring 10a and a spindle 10b provided in an integral manner at the distal end of the leaf spring so that the collision damper unit 10 may collide with and move away from the supporting piece 2b at the time of oscillation. The natural oscillation frequency of the collision damper unit 10 is caused to coincide with the oscillation frequency of the supporting piece 2b in the focusing direction, by adjusting the spring constant of the leaf spring 10a and the weight of the spindle 10b. In addition, a portion where the supporting piece 2b collides with the collision damper unit 10 is treated by wear-resistant processing. When the supporting piece 2b oscillates in the focusing direction at the time so operation, the collision damper unit 10 oscillates at the same frequency as that of the supporting piece 2b and with the opposite phase, and the spindle 10b collides with the supporting piece 2b, thus offsetting the oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens actuator used for an optical disk device, a magneto-optical disk device, and the like.

[0002]

2. Description of the Related Art Conventionally, for example, in an optical disk device or a magneto-optical disk device, an objective lens has been used to accurately condense light on each track of a disk or condense reflected light on a light receiving element. The movable member provided is spring-supported at a neutral position so as to be movable in a focusing direction and a tracking direction with respect to a base member by four leaf springs, and a magnetic actuator including a focusing coil, a tracking coil, and a magnet is provided. An optical head for driving and controlling the movable member is known, but an unnecessary vibration mode in a spring system for holding the movable member,
The problem is the inclination of the objective lens with respect to the optical axis in the low frequency range. Generally, these can be reduced by making the action point position of the inertia force of the movable portion coincide with the action point position of the coil driving force and the restoring force of the spring as much as possible.
As disclosed in Japanese Patent No. 437, a structure in which the shape of the movable member and the coil mounting position are symmetrical with respect to the optical axis of the objective lens is known.

However, in this structure, since it is difficult to reduce the size and weight, it is necessary to have a structure in which the movable member shape and the coil mounting position are asymmetric with respect to the optical axis of the objective lens.

A movable member for supporting an objective lens in such an optical head is disclosed in, for example, JP-A-6-3253.
As disclosed in Japanese Patent Application Publication No. 87-87, a main body portion provided with relatively large vertical through holes for loosely inserting a core erected on a base member, and a main body portion extending from the main body portion in a direction orthogonal to a focusing direction. There is a type that includes a projecting support piece of an objective lens and holds a focusing coil and a tracking coil in vertical holes of the main body.

[0005]

On the other hand, in recent years, it has been desired to improve the disk rotation speed and head speed of the above-described optical disk device and magneto-optical disk device to increase the access speed. At that time, vibration of the movable member floatingly supported becomes a problem. In particular, in the case where the supporting piece of the objective lens is protruded from the main body in a direction perpendicular to the focusing direction as described above, the vibration becomes the most problematic because the supporting piece becomes thin, and in some cases, the read / write operation is performed. There is a possibility that a write error occurs.

For example, Japanese Patent Application Laid-Open No. Hei 5-197991 discloses a structure in which a so-called inertial damper using a spring and a weight is provided to suppress rotation in a direction perpendicular to the focusing direction. It is also conceivable to apply an inertia damper that directly suppresses the vibration of the support piece by applying it directly to the body where the support piece of the objective lens protrudes from the main body. It is difficult to provide a damper, which not only complicates the structure, but also increases the weight and reduces the design flexibility.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and a main object of the present invention is to suppress the vibration of a movable member supporting an objective lens and improve a disk rotation speed and a head speed. It is an object of the present invention to provide an objective lens actuator which enables an optical disk device, a magneto-optical disk device, and the like to have a high speed and a high recording density.

[0008]

According to the present invention, there is provided a base member which is spring-supported at a neutral position so as to be movable in a focusing direction and a tracking direction.
And an objective lens actuator having a movable member including a main body having a focusing coil and a tracking coil, and a support piece of the objective lens protruded from the main body in a direction orthogonal to a focusing direction. A collision damper device including only a spring or a spring and a weight protruding from the main body so as to be parallel to the support piece along the focusing direction and to be able to hit / separate from the support piece during vibration. An objective lens actuator, wherein the collision damper device vibrates and hits the support piece that vibrates in the focusing direction when the movable member vibrates, in a phase opposite to the support piece. Is achieved by providing

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of a main part of an optical head used in an optical disk device or a magneto-optical disk device to which the present invention is applied, and FIG. 2 is a plan view thereof. The optical head includes an objective lens 1 and a support piece 2 for supporting the objective lens 1 at one end.
b, a base member (not shown) adapted to be roughly moved by a drive device (not shown) provided on the apparatus body side, and a focusing direction and a tracking direction for moving the movable member 2 to the base member. And four parallel plate springs 4a, 4b, 4c, and 4d as spring means for supporting a spring at a neutral position so as to be movable in the vertical direction. An upper and lower through hole 2c is formed at an intermediate portion of the main body 2a of the movable member 2, and a focusing coil 5 is adhered to a side of the movable member 2 which is opposite to the supporting side of the objective lens 1, and a front end face of the focusing coil 5 is provided. A pair of left and right tracking coils 6 are adhered to. On the other hand, magnet units 7 and 8 composed of a yoke and a magnet are erected on the base member 3,
One magnet unit 7 protrudes into the focusing coil 5, and the other magnet unit 8 protrudes into a front portion of the vertical through hole 2 c where the focusing coil 5 is not provided, and faces the tracking coil 6.

Of the four leaf springs 4a, 4b, 4c, 4d, one ends of the lower leaf springs 4a, 4b are bonded to a pair of flanges 2d projecting below the movable member 2 in the tracking direction. One end of the upper leaf springs 4c and 4d is
Is adhered to the upper end surface. Each leaf spring 4a, 4b, 4
The other ends of c and 4d are fixed to the back plate 3 of the base member. The leaf springs 4a, 4b, 4c, and 4d also serve as wires for electrically connecting the focusing coil 5 and the tracking coil 6 to a power source via an external control device (not shown).

When viewed from above in the focusing direction, the lower leaf springs 4a, 4b are offset outward from the upper leaf springs 4c, 4d so as not to overlap with each other. Thereby, each leaf spring 4a, 4b, 4c,
4d can be attached so as not to interfere with each other from the upper side in the focusing direction, and the adhesive can be simultaneously cured by irradiating ultraviolet rays from one direction.

On the other hand, as shown in FIGS. 2 (a) and 2 (b), the main body 2a is supported in parallel with the support piece 2b along the focusing direction, and supported during vibration. A collision damper device 10 including a U-shaped leaf spring 10a and a weight 10b integrally provided by, for example, shaving is protruded from the tip of the U-shaped leaf spring 10a so as to be able to strike / separate the piece 2b. The collision damper device 10 includes a spring 10
By adjusting the spring constant of a and the weight of the weight 10b, the natural frequency of the movable member 2 substantially matches the higher-order resonance frequency of the movable member 2 in the focusing direction, that is, the vibration frequency of the support piece 2b in the focusing direction. I have. This higher-order resonance frequency can be specified in advance at the time of design, for example, by analysis using the finite element method. The collision damper device 1
0 is normally in contact with the supporting piece due to the deflection of the leaf spring. Further, a portion of the support piece 2b which collides with the collision damper device 10 is preferably subjected to a wear prevention treatment.

Next, the operation of the present embodiment will be described with reference to FIGS. 2, 3A and 3B. First, the collision damper device 10 normally comes into close contact with the support piece 2b with the biasing force of the spring 10a. Next, during operation of the present optical head, the supporting piece 2b is particularly moved in the focusing direction.
When the vibration occurs, the collision damper device 10 also vibrates at the same frequency and in the opposite phase, and the weight 10b at the tip thereof
The portion abuts against the support piece 2b and cancels the vibration of the support piece 2b. This is shown in section B of FIG. FIG.
(A) shows the relationship between the frequency and the vibration intensity when the collision damper device 10 is not provided.

As shown in part A of FIG. 3A, when there is no collision damper device 10, a high-order resonance frequency (about 23 kHz)
Was about 40 dB, the collision damper device 1
By providing 0, it can be seen that the peak frequency is remarkably reduced to about 15 dB, although the generated frequency is slightly lowered due to its weight.

It is needless to say that the present invention is not limited to the above-described embodiment, and various applications are possible. For example, in the present embodiment, the collision damper device is provided below the supporting piece of the objective lens in FIG. Although it is provided on the side, it may be provided on the upper side or on both sides, and the material and shape of the spring may be any known spring as long as it can be assembled. Furthermore, the weight may not be provided as necessary, that is, depending on the frequency, and in some cases. Further, in the above-described embodiment, the collision damper device is provided which strikes the lens support piece along the focusing direction to suppress the vibration in the focusing direction. However, the lens support piece along the tracking direction is provided to suppress the vibration in the tracking direction. Further, another collision damper device may be further provided.

[0017]

As is apparent from the above description, according to the objective lens actuator of the present invention, the movable member having the objective lens supporting piece projecting from the spring-supported main body in the direction orthogonal to the focusing direction. In the objective lens actuator having the above, a collision damper device composed of only a spring or a spring and a weight is protruded from the main body so as to be able to strike / separate the support piece during vibration, and this collision damper apparatus is combined with the support piece. By vibrating in opposite phases and hitting the support piece, the vibration of the higher resonance frequency of the support piece is canceled out, the vibration of the movable member supporting the objective lens is suppressed, and the disk rotation speed and head speed are reduced. It is possible to increase the speed of an optical disk device, a magneto-optical disk device, and the like.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an optical head used in an optical disk device, a magneto-optical disk device, or the like to which the present invention is applied.

2A is a simplified bottom view of the optical head shown in FIG. 1, and FIG. 2B is a side view thereof.

3A is a graph showing a relationship between a frequency and a vibration intensity without a collision damper device, and FIG. 3B is a graph showing a relationship between a frequency and a vibration intensity with a collision damper device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Movable member 3 Back plate 2a Main part 2b Support part 2c Vertical through hole 2d Flange 4a, 4b, 4c, 4d Leaf spring 5 Focusing coil 6 Tracking coil 7, 8 Magnet unit 10 Collision damper 10a Leaf spring 10b Weight

Claims (5)

[Claims] 1. A main body having a focusing coil and a tracking coil which is spring-supported at a neutral position so as to be movable in a focusing direction and a tracking direction by a base member, and protrudes from the main body in a direction orthogonal to the focusing direction. An objective lens actuator having a movable member composed of a supporting piece of the objective lens provided and being parallel to the supporting piece along the focusing direction, and being attached to the supporting piece at the time of vibration. A collision damper device comprising only a spring or a spring and a weight protruding from the main body so as to be able to strike / separate from each other; and the support piece which repeatedly tilts in the focusing direction when the movable member vibrates, Wherein the collision damper device oscillates and strikes at a phase opposite to that of the object. Lens actuator. 2. The objective lens actuator according to claim 1, wherein a surface of the support piece at a position where the support piece abuts is subjected to a wear prevention treatment. 3. The objective lens actuator according to claim 1, wherein the spring is deflected so that the collision damper device normally contacts the support piece. 4. The leaf spring according to claim 1, wherein the weight is formed by increasing the thickness of a part of the leaf spring.
The objective lens actuator according to any one of the above. 5. A spring alone or a spring protruding from the main body so as to be parallel to the support piece along the tracking direction and to be able to hit / separate from the support piece during vibration. 5. The objective lens actuator according to claim 1, further comprising a collision damper device formed of a weight.