JP3561379B2 - Objective lens actuator - Google Patents

Description

[0001]
TECHNICAL 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]
[Prior art]
Conventionally, for example, in an optical disc device or a magneto-optical disc device, a movable member provided with an objective lens for accurately condensing light on each track of the disc or condensing the reflected light on a light receiving element. Is supported at a neutral position by four leaf springs so as to be movable in a focusing direction and a tracking direction with respect to a base member, and the movable member is driven by a magnetic actuator composed of a focusing coil, a tracking coil, and a magnet. An optical head for controlling is known, but there are problems with an unnecessary vibration mode in a spring system holding the movable member and an inclination of the objective lens with respect to the optical axis in a low frequency range. Generally, these can be reduced by making the action point position of the movable portion inertia force and the coil drive force and the restoring force action point position of the spring as close as possible. For example, as disclosed in JP-A-7-78437. 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.
[0003]
However, in this structure, since it is difficult to reduce the size and weight, it is necessary to have a structure in which the shape of the movable member and the coil mounting position are asymmetric with respect to the optical axis of the objective lens.
[0004]
In such an optical head, as a movable member for supporting an objective lens, for example, as disclosed in JP-A-6-32587, a relatively large member for loosely inserting a core erected on a base member is used. The main body is provided with a vertical through-hole, and a supporting piece of an objective lens protruded from the main body in a direction perpendicular to the focusing direction. A focusing coil and a tracking coil are provided in the vertical through-hole of the main body. Some are retained.
[0005]
[Problems to be solved by the invention]
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 portion in a direction orthogonal to the focusing direction as described above, the vibration becomes the most problematic because the supporting piece is thin, and in some cases, the read / write operation is performed. There is a possibility that a writing error occurs.
[0006]
Therefore, for example, Japanese Patent 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 orthogonal to a focusing direction. It is conceivable to apply an inertia damper that directly suppresses the vibration of the support piece by directly applying the support piece of the objective lens to the protruding support piece, but the above-described inertia damper is provided so as not to interfere optically. It is difficult to do so, and not only the structure becomes complicated, but also there is a problem that the weight is increased and the degree of freedom in design is reduced.
[0007]
The present invention has been made in view of the above-described problems of the related art, and a main object of the present invention is to suppress the vibration of a movable member that supports an objective lens and to improve a disk rotation speed and a head speed, Accordingly, it is an object of the present invention to provide an objective lens actuator that can make an optical disk device, a magneto-optical disk device, and the like compatible with high speed and high recording density.
[0008]
[Means for Solving the Problems]
According to the present invention, the object described above is supported by a base member at a neutral position so as to be movable in a focusing direction and a tracking direction, and a main body having a focusing coil and a tracking coil, and a focusing direction from the main body. An objective lens actuator having a movable member composed of a support piece of the objective lens protruded in a direction orthogonal to the support piece, so as to be parallel to the support piece along the focusing direction, and at least. A sliding contact damper device comprising a leaf spring protruding from the main body so that the free end portion is always urged in a direction in which the free end is in contact with the support piece, and repeats in a focusing direction when the movable member vibrates. The sliding contact damper device slides against the support piece that tilts to attenuate vibration. It is achieved by providing a lens actuator.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
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 roughly moves by an objective lens 1, a movable member 2 supporting the objective lens 1 on one end supporting piece 2 b, and a driving device (not shown) provided on the apparatus main body side (not shown). And four parallel leaf springs 4a, 4b, 4c, 4d as spring means for supporting the movable member 2 on the base member at a neutral position so as to be movable in the focusing direction and the tracking direction. have. An up-and-down 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 attached near a side opposite to the supporting side of the objective lens 1, and a front end of the focusing coil 5 is provided. A pair of left and right tracking coils 6 are adhered to the surface. On the other hand, magnet units 7 and 8 composed of a yoke and a magnet are erected on the base member 3, one of the magnet units 7 protrudes into the focusing coil 5, and the other magnet unit 8 is the one of the focusing coil 5 in the vertical through hole 2 c. And the tracking coil 6 is rushed into the front part.
[0011]
Of the four leaf springs 4a, 4b, 4c and 4d, one ends of the lower leaf springs 4a and 4b are bonded to a pair of flanges 2d projecting in the tracking direction below the movable member 2, and One ends of the springs 4c and 4d are bonded to the upper end surface of the movable member 2. The other end of each leaf spring 4a, 4b, 4c, 4d is 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).
[0012]
On the other hand, as shown in FIGS. 2 (a) and 2 (b), a U-shaped leaf spring is provided on the main body 2a so as to be substantially parallel to the supporting piece 2b along the focusing direction. And a sliding damper device 10 comprising The leaf spring of the sliding contact damper device 10 is inclined from the base end side toward the play side, and the free end portion 10a is bent so as to be pressed by the support piece 2b. 2b. The sliding resistance of the support piece 2b during vibration is adjusted by adjusting any one or more of the spring constant, the amount of deflection, and the surface roughness of the sliding contact surface of the sliding contact damper device 10. I am getting it. The surface roughness can be adjusted by surface finishing or coating on the sliding contact damper device 10 side and / or the support piece 2b side. The free end of the free end 10a of the sliding contact damper device 10 is curved outward so as not to bite into the support piece 2b.
[0013]
Next, the operation of the present embodiment will be described with reference to FIGS. 2, 3A and 3B. If vibration occurs in the support piece 2b in the focusing direction during operation of the present optical head, sliding friction similar to that in the case of a leaf spring, for example, occurs with the sliding contact damper device 10. As a result, the vibration of the support piece 2b is attenuated. This situation is shown in part B of FIG. FIG. 3A shows the relationship between the frequency and the gain when the sliding contact damper device 10 is not provided.
[0014]
As shown in part A of FIG. 3A, when the peak of the higher-order resonance frequency (about 22 kHz) was about 11.3 dB without the sliding contact damper device 10, by providing the sliding contact damper device 10. It can be seen that the peak frequency is remarkably reduced to about 5.2 dB although the generated frequency is slightly lowered due to its weight. Here, a similar experiment was carried out on a plate spring similar to the above attached so as not to contact the support piece 2b, but no vibration damping effect was obtained.
[0015]
In the above embodiment, the vibration in the focusing direction has been mainly described. However, it goes without saying that the structure of the present invention has an effect of damping the vibration in the tracking direction. Further, a sliding contact damper device similar to the above may be separately provided for preventing vibration in the tracking direction.
[0016]
It is needless to say that the present invention is not limited to the above embodiment, and various applications are possible. For example, in the present embodiment, the sliding contact damper device is provided on the upper side of the supporting piece of the objective lens in FIG. The material and shape of the leaf spring may be any known ones as long as they can be assembled.
[0017]
【The invention's effect】
As is apparent from the above description, according to the objective lens actuator according to the present invention, the objective lens actuator having the movable member in which the support piece of the objective lens protrudes from the spring-supported main body in the direction orthogonal to the focusing direction. In this case, a sliding contact damper device made of a leaf spring is projected from the main body so that at least the free end portion is in sliding contact with the supporting piece when vibrating, and the sliding contact damper device is slidably contacted when the supporting piece vibrates. By attenuating the vibration, the vibration of the movable member that supports the objective lens is suppressed, the disk rotation speed and the head speed can be improved, and the speed of the optical disk device, the magneto-optical disk device, and the like can be increased.
[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 side view of the optical head of FIG. 1, and FIG. 2B is a plan view thereof.
3A is a graph showing a relationship between a frequency and a gain when there is no sliding contact damper device, and FIG. 3B is a graph showing a relationship between a frequency and a gain when there is a sliding contact damper device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Objective lens 2 Movable member 3 Back plate 2a Main part 2b Support part 2c Upper and lower through holes 2d Flanges 4a, 4b, 4c, 4d Leaf spring 5 Focusing coil 6 Tracking coil 7, 8 Magnet unit 10 Sliding contact damper device 10a Free end

Claims (4)

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 on a base member, and the object protruding from the main body in a direction orthogonal to the focusing direction. An objective lens actuator having a movable member composed of a lens support piece,
From a leaf spring protruding from the main body so as to be parallel to the support piece along the focusing direction, and at least the free end is urged in a direction to always contact the support piece. Having a sliding damper device,
The objective lens actuator, wherein the sliding contact damper device slides on the support piece that repeatedly tilts in the focusing direction when the movable member vibrates, and attenuates the vibration. 2. The objective lens actuator according to claim 1, wherein the supporting piece and / or the sliding contact surface of the sliding contact damper device are treated so as to increase a friction coefficient. 3. The leaf spring is inclined from the base end side to the free end side, and the free end is bent so as to be pressed by the support piece. The leaf spring and the support piece are adjusted by adjusting the amount of bending. 3. The objective lens actuator according to claim 1, wherein a frictional force between the objective lens actuator and the objective lens actuator is adjusted. 4. The free end of the leaf spring is curved in a direction opposite to the support piece, and the bent portion comes into contact with the support piece. An objective lens actuator according to claim 1.

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