JP2602855B2 - Objective lens drive - Google Patents

Description

Description: Object of the Invention (Industrial application field) The present invention relates to an objective lens driving device of an optical pickup used in an optical information recording / reproducing device, and in particular, a resonance phenomenon at the time of driving a lens. The present invention relates to an objective lens driving device that suppresses the phenomenon.

(Prior Art) In an optical information recording / reproducing apparatus using a laser beam, the laser beam is focused on a minute spot by an objective lens to read / write a signal. In order to accurately focus the light spot on the recording medium surface, it is necessary to suppress the resonance phenomenon in the mechanism for driving the objective lens, that is, the objective lens driving device, and to improve the followability of the objective lens to the recording medium. .

Therefore, conventionally, a viscoelastic body is attached between the movable portion and the base, the elastic support member itself, or between the fixed portion and the elastic support member, and the action of the viscoelastic body suppresses the resonance phenomenon. As a first conventional example, in a mechanism in which a movable body holding an objective lens is supported by four wires as elastic bodies, a viscoelastic body is injected into a portion where the wires are attached to a base.
A technique for suppressing the vibration of the movable body has been adopted. As a second conventional example, in a mechanism in which a leaf spring supports an objective lens holder (movable body), a leaf spring and a viscoelastic body are laminated,
There is a method to increase the vibration damping effect. As a third conventional example, in a mechanism for supporting a movable body with the four wires, a method of covering each wire with a tubular viscoelastic body or penetrating the wire into the viscoelastic body has been adopted.

However, this kind of mechanism has the following problems. That is, when a viscoelastic body is used to increase the vibration damping effect, the displacement speed inside the viscoelastic body itself is increased, and the mass (M) of the movable body including the objective lens and the movable body as a holding member thereof is reduced. , Viscous damping constant of viscoelastic material (C)
It is necessary to increase the ratio (C / M) to secure the damping effect. However, in the above-mentioned conventional example, it cannot be said that the viscoelastic body is attached to the portion where the vibration amplitude is large, and C becomes small, so that a sufficient vibration damping effect cannot be obtained.

In addition, since the axis of action of the vibration-damping force exerted on the movable portion including the viscoelastic body objective lens is at a mounting position that does not pass through the center of gravity of the movable portion, the inclination of the optical axis or the abnormal resonance phenomenon of the movable portion May be caused. In addition, there are few viscoelastic materials with sufficient vibration damping effect and excellent environmental characteristics such as temperature characteristics, and a large space is required to provide a sufficient vibration damping effect, which causes an increase in the size of the optical pickup. was there.

(Problems to be Solved by the Invention) As described above, conventionally, in a mechanism in which a movable body holding an objective lens is supported by an elastic support, a plurality of resonance phenomena are caused by the mass of the movable part and the rigidity of the elastic support. As a result, it becomes difficult to make the laser light follow the recording medium. In order to prevent this, there is a method using a viscoelastic body, but none of them can obtain a sufficiently large vibration damping effect, and further, there is a problem that the apparatus configuration becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an objective objective lens driving device capable of suppressing an extra resonance phenomenon of an objective lens and miniaturizing the device configuration. To provide.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to provide an installation portion for a viscoelastic body on a movable body having a large vibration amplitude and to take a sufficiently high displacement speed of the viscoelastic body. .

That is, the present invention provides an objective having an objective lens, a movable body that holds the objective lens, an elastic support body that movably supports the movable body with respect to a fixed part, and a driving unit that displaces the movable body. In the lens driving device, the elastic support body is formed by intersecting a plurality of elastic bodies near a center of gravity of the movable body, and a viscoelastic body is arranged near an intersection of these elastic bodies. This is to cover a part of the elastic support.

(Operation) According to the present invention, since the viscoelastic body is directly attached to the movable body holding the objective lens, it is possible to increase the displacement speed in the viscoelastic body. Moreover, the mounting position and the mounting amount can be adjusted in accordance with the magnitude of the relative displacement between the movable body of the viscoelastic body and the elastic support, and the vibration damping effect can be adjusted.

In addition, by making the axis of action of the vibration-damping force of the viscoelastic body applied to the movable part coincide with the center of gravity of the movable body, it is easy to prevent the inclination of the optical axis of the objective lens and the abnormal resonance phenomenon of the movable body. . Furthermore, by using a wire as the elastic support, inserting this wire into the through-hole provided in the movable body and injecting a viscoelastic body, it is possible to reduce the weight while maintaining the rigidity of the movable body. is there. Further, in the configuration in which the viscoelastic body is injected into the through-hole, it is possible to prevent the viscoelastic body from scattering due to surface tension.

(Examples) Hereinafter, details of the present invention will be described with reference to the illustrated examples.

1 to 3 show a schematic configuration of an objective lens driving device according to a first embodiment of the present invention. FIG. 1 is a plan view, FIG. 2 is a perspective view, and FIG. 3 is a side view. It is. In these drawings, the same parts are denoted by the same reference numerals.

In the figure, reference numeral 1 denotes a base made of a magnetic material.
Is fixed to an end of the support mechanism. One end of an elastic support 3 having a configuration in which four wires cross in a cross (cross wire) is attached to the support mechanism fixing portion 2 via a wire fixing portion 9. A movable body 8 holding the objective lens 4 and holding the focusing coil 5 and the tracking coil 6 is attached to the other end of the elastic support 3 via a wire fixing unit 9.

Here, the elastic support 3 is composed of wires 3a, 3b arranged in parallel with each other in a plane perpendicular to the base 1, and wires 3c, 3d similarly arranged in parallel in a plane orthogonal to the base 1. It is configured. The plane formed by the wires 3a and 3b and the plane formed by the wires 3c and 3d are arranged so as to intersect at substantially the center of the base 1.

The vicinity of the intersection of the cross wires constituting the elastic support 3 is
As shown in FIG. 4, a wire passes through the inside of the through hole 10 opened in the movable body 8, and a viscoelastic body 11 made of gel-like silicone or the like is injected into the inside of the through hole 10. . The center of gravity Gb of the movable part (the movable body 8 holding the objective lens 4, the focusing coil 5, and the tracking coil 6)
Has a structure substantially coincident with the vicinity of the intersection of the upper and lower cross wires. When the movable body 8 moves in the focusing direction and the tracking direction, the wire is displaced in the viscoelastic body 11. At this time, as shown in FIG. 5, the damping force of the viscoelastic body 11 is distributed, and the viscoelasticity is set so that the axis of action of the damping force exerted on the movable portion of the damping force 11 substantially coincides with the center of gravity Gb. Body 11 has been injected.

When the injection amount of the viscoelastic body 11 is limited, the sixth
As shown in the figure, by injecting the viscoelastic body 11 into a portion where the relative displacement of the wire is large, the vibration damping effect can be enhanced. Further, as shown in FIG. 7, by increasing the injection amount of the viscoelastic body 11, it becomes possible to further enhance the vibration damping effect,
By adjusting the injection amount, it is possible to realize an optimal vibration damping effect.

The base 1 is provided with two magnetic circuits each including a permanent magnet 7 and a yoke 12.
Are arranged such that a part of the focusing coil 5 and a part of the tracking coil 6 are inserted in the magnetic field generated by the above.

In such a configuration, when an electric current is applied to the focusing coil 5 and the tracking coil 6, the objective lens 4 is translated and rotated in the respective directions together with the movable body 8 by the driving force in both the focusing and tracking directions, and information on the recording medium is recorded. Can be read and written. In this case, since the viscoelastic body 11 is directly attached to the movable body 8, the displacement speed in the viscoelastic body 11 can be increased, and a sufficiently large vibration damping effect can be obtained. In addition, since the axis of action of the damping force by the viscoelastic body 11 is matched with the center of gravity of the movable part, it is possible to prevent the inclination of the optical axis of the objective lens 4 and the occurrence of abnormal resonance of the movable part.

Further, since the viscoelastic body 11 is injected into the through hole 10 of the movable body 8 through which the cross wire constituting the elastic support mechanism 3 is inserted, a special space for mounting the viscoelastic body 11 is required. In addition, the size of the movable body 8 is not increased. For this reason, the movable body 8 can be reduced in size and weight, and the vibration suppression effect can be improved from this point as well. Also, the viscoelastic body 11
Is injected into the through-hole 10 so that the viscoelastic body 11
Can be prevented from scattering.

Note that the present invention is not limited to the above-described embodiments. For example, the viscoelastic body is not limited to gel silicone, and an elastic body having viscosity can be appropriately selected and used. Furthermore, the conditions such as the injection amount and the embedding amount of the viscoelastic body may be appropriately determined according to the specifications. In addition, various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above in detail, according to the present invention, an extra resonance phenomenon of the objective lens and inclination of the optical axis can be effectively suppressed by the action of the viscoelastic body. It is possible to avoid the disadvantage that the device configuration becomes large due to the addition. Therefore, a great effect can be obtained as an objective lens driving device for an optical pickup.

[Brief description of the drawings]

FIGS. 1 to 3 each show a schematic configuration of an objective lens driving device according to a first embodiment of the present invention.
Fig. 2 is a plan view, Fig. 2 is a perspective view, Fig. 3 is a side view, Fig. 4 is a schematic view showing a state near a through hole provided in a movable body, and Figs.
FIG. 7 to FIG. 7 are cross-sectional views each showing a state of injection of the viscoelastic body. DESCRIPTION OF SYMBOLS 1 ... Base, 2 ... Fixing part of support mechanism, 3, 22 ... Elastic support, 4 ... Objective lens, 5 ... Focusing coil,
6 tracking coil, 7 permanent magnet, 8 movable body, 9 wire fixing part, 10 through hole, 11 viscoelastic body, 12 yoke

Claims (6)

(57) [Claims] 1. An objective comprising: an objective lens; a movable body that holds the objective lens; an elastic support body that movably supports the movable body with respect to a fixed portion; and a driving unit that displaces the movable body. In the lens driving device, the elastic support body is formed by intersecting a plurality of elastic bodies near a center of gravity of the movable body, and a viscoelastic body is arranged near an intersection of these elastic bodies. An objective lens driving device, which covers a part of the elastic support. 2. The objective lens driving device according to claim 1, wherein the axis of action of the viscoelastic body for damping force passes through the approximate center of gravity of the movable body. 3. The objective lens driving device according to claim 1, wherein said elastic support comprises a plurality of wires. 4. The elastic support body includes a pair of first wires arranged so as to be parallel to each other in a plane parallel to an optical axis of the lens, and a pair of first wires parallel to the optical axis of the lens. A pair of second wires arranged so as to be parallel to each other in a plane different from that of the first pair of wires;
The intersection of two planes including the pair of wires and the pair of second wires is substantially coincident with the position of the center of gravity of the movable body. Objective lens drive. 5. The objective lens according to claim 3, wherein the viscoelastic body is injected into a through-hole provided in the movable body and through which the wire is inserted. Drive. 6. The viscoelastic body according to claim 6, wherein the size of the through-hole into which the viscoelastic body is injected is made larger than the movable range of the elastic support, and the viscoelastic body does not scatter when the movable body moves. The objective lens driving device according to claim 5.