JPS62229540A - Optical system driver - Google Patents

Abstract

PURPOSE:To prevent the tilt of an optical axis by forming a plate spring supporting an optical system by a fiber reinforced plastic by oblique fiber reinforcement so as to hardly cause the subresonance due to the effect of light and the torsion. CONSTITUTION:The fiber reinforced plastic (FRP) subject to oblique fiber reinforcement is used for plate springs 12, 12a and 13, 13a. Thus, the generation of torsion is prevented. A unique behavior is shown in the FRP by controlling the orientation of fibers in case of the cunti-lever support. That is, in using the FRP 15 subject to oblique fiber reinforcement apart from the isotropy of a material such as a metal, even when a force F10 is exerted to any of left/right free ends of a plate member 15, no torsion is caused and the plate is deformed elastically in a direction in parallel with the force F10. Thus, even when a force F11 is exerted to any of left/right free ends of the plate spring 12 in the focus (y axis) direction, no torsion around the x-axis is caused and the spring is deformed elastically in the focus (y axis) direction. Thus, the tilt of the optical axis due to the torsion is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical system drive device, and particularly in an optical information recording/reproducing device such as an optical disk device, a magneto-optical disk device, or a digital audio device. This invention relates to an optical system drive device that uses a leaf spring to support and drive the optical system.

(Prior Art) Generally, in an optical information recording/reproducing device such as an optical disk device, information pits (width of about 0.5 μm,
In order to read information recorded in the area (about 0.9 to 3.3 μm in length), first, a light beam is focused on a minute spot by an optical system such as an objective lens, and is irradiated onto the information pit. At this time, the reflected light from the information recording medium optically changes depending on the presence or absence of information. By detecting this change with a photodetector, a reproduced signal corresponding to the information pits can be obtained. At this time, it is extremely important that the minute spot of the light beam always accurately scans the information pit row on the information recording medium. For this purpose, a focusing function that corrects a focus shift caused by warpage of the information recording medium, etc., and a tracking function that corrects an irradiation position shift caused by eccentricity of the information recording medium, etc. are required.

As a means for realizing the focusing function and the tracking function, a method is known in which the optical system is supported by a leaf spring and the electromagnetic force generated by a magnetic circuit consisting of a coil and a magnetic member is utilized.

FIG. 3 is a perspective view showing a conventional optical system drive device having a focusing function and a tracking function. In this figure, ■ is a focus drive coil, 2 is a tracking drive coil, and each magnet 3 is installed opposite the coil 1.2 in the Z-axis direction (however, one is omitted in the figure). , yoke 4 constitute a magnetic circuit for focus drive and tracking drive. Reference numeral 5 denotes an optical system holder on which an objective lens 6 is mounted as an optical system, and the optical system holder 5 is fixed inside the focus drive coil 1. 7 and 7a are plate springs made of metal etc. that support the objective lens 6 movably in the focus direction (y-axis direction), and 8 and 8a support the objective lens 6 so that it can be movably moved in the tracking direction (X-axis direction). These are leaf springs made of metal or the like, and the leaf springs 7, 7a and 8, 8a are arranged parallel to each other. 9 is an intermediate member that connects the leaf springs 7, 7a and 8, 8a. Reference numeral 10 denotes a support stand mounted on a base 11, and one end surface of a leaf spring 8.8a is fixed to the support stand 10.

In the device configured as described above, by applying a current to the coil 1.2, each leaf spring 7, 7a and 8, 8a is is elastically deformed, and the objective lens 6
can be driven in the focusing direction and tracking direction.

(Problems to be Solved by the Invention) In the above-described apparatus, when the objective lens 6 is driven in the focus direction (y-axis direction), as shown in FIG. A force equal to F I+ F
When z(F,=F2) acts, the leaf springs 7, 7
a is elastically deformed in the focus direction (y-axis direction) without twisting or the like. At this time, as shown in FIG. 4(b), different forces Fx, F# (F
3>Fa), the side on which force F3 is applied undergoes greater elastic deformation and twisting occurs around the X-axis.
The optical axis A of the objective lens 6 is shifted from the focus direction (y-axis direction).

Furthermore, when driving the objective lens in the tracking direction (X-axis direction), as shown in FIG. The force F S + F 6 (F
5=Fh), the leaf springs 8, 8a are elastically deformed in the tracking direction (X-axis direction) without twisting or the like. At this time, as shown in FIG. 5(b), the leaf spring 8
Different forces FT, Fa (Fy >F
When a) is applied, the side on which the force F7 is applied undergoes greater elastic deformation and twisting occurs around the z-axis, causing the optical axis A of the objective lens 6 (not shown) to move in the tracking direction (X-axis direction).
deviate from

Furthermore, the leaf springs 7, 7a and 7a are also affected by the misalignment of the centers of gravity of the coils 1.2, the optical system holder 5, and the objective lens 6 attached to the leaf springs 7, 7a, the difference in magnetic force between the opposing magnets 3, and the influence of gravity. 8 and 8a are twisted.

As described above, since the optical system is supported and driven by a leaf spring made of a material such as metal, the optical axis may be tilted due to twisting of the leaf spring. Also,
There is a drawback that resonance occurs with high-frequency drive signals and operation tends to become unstable.

The present invention was made for the purpose of solving the above conventional problems,
It is an object of the present invention to provide an optical system driving device that can stably drive an optical system without causing the optical axis to tilt.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an optical system drive device in which the optical system is supported and driven by a temporary spring, in which the leaf spring is made of fiber-reinforced plastic reinforced with diagonal fibers. (hereinafter referred to as FRP).

(Example) Hereinafter, the present invention will be explained in detail with reference to an illustrated example.

FIGS. 1A and 1B are perspective views showing a deformed state of a temporary spring of an optical system drive device according to the present invention. Note that the same members as in the conventional example will be described with the same reference numerals.

In this figure, 12.12a and 13.13a are leaf springs made of oblique fiber-reinforced FRP, respectively, and the leaf springs 12.12a and 13.13a are parallel to the X-axis direction and the X-axis direction, respectively. It is set up oppositely. Similarly to the conventional example shown in FIG. 3, the leaf springs 12, 12a
supports the objective lens 6 movably in the focus direction (y-axis direction), leaf springs 13 and 13a support the objective lens 6 (not shown) in a movable manner in the tracking direction (X-axis direction), and the intermediate member IO are connected via. In addition, 5 is an optical system holder equipped with an objective lens 6, and 11 is a leaf spring 1.
This is a support stand to which one end surface of 3.13a is fixed.

The optical system drive device according to the present invention is configured as described above, and by using FRP reinforced with oblique fibers for the leaf springs 12, 12a and 13.13a, it is possible to prevent twisting. In other words, PPP exhibits unique behavior when supported in a cantilevered manner by controlling the directionality of the fibers.

That is, as shown in FIG. 2(A), when a plate-shaped member 14 made of an isotropic material such as metal is supported on a cantilever and a force F is applied to one of the left and right free ends, a biaxial force is applied. Although twisting occurs around the circumference, as shown in Figure 2 (b), the F
When RP15 is used, it is elastically deformed in a direction parallel to the applied force F1° without twisting.

This is because the FRP does not have a twisting mode due to the orthorhombic fiber reinforcement.

Therefore, as shown in FIG.
axial direction), it is elastically deformed in the focus direction (y-axis direction) without twisting around the X-axis.

In addition, as shown in FIG.
axial direction), it is elastically deformed in the tracking direction (X-axis direction) without twisting around the Z-axis.

Furthermore, the plate springs 12.12a and 13.13a are less likely to resonate due to their characteristics as shown in FIG. 2(b).

Furthermore, although this example uses a temporary spring to support and drive the optical system in the focusing direction and tracking direction,
The device may have a structure in which a leaf spring is used for support and drive in either the focusing direction or the tracking direction.

Further, although this embodiment is an example in which the present invention is applied to an optical system drive device of an optical disk device, it is obvious that the present invention can also be applied to other optical devices such as a shape detection device and a laser processing machine.

(Effects of the Invention) As explained above, the optical system drive device according to the present invention has the following features:
By using FRP reinforced with diagonal fibers for the leaf spring,
Since twisting and sub-resonance due to its influence are less likely to occur, it is possible to prevent the optical axis from collapsing and to drive the optical system stably.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are both perspective views showing deformed forms of the leaf spring of the optical system drive device according to the present invention, and FIG. 2(a)
is a perspective view showing the twisted state of an isotropic material, Figure 2 (b)
3 is a perspective view showing a deformed state of FRP reinforced with orthorhombic fibers, FIG. 3 is a perspective view showing an optical system drive device in a conventional example, FIGS. B) is a perspective view showing a deformed state and a twisted state of a leaf spring of an optical system drive device in a conventional example. 5... Optical system holder, 12, 12a, 13.13a.
...Plate spring. Agent Patent Attorney Minoru Yamashita Children Figure 1 Figure 2

Claims (1)

[Claims] An optical system drive device in which an optical system is supported by a leaf spring, wherein the leaf spring is made of diagonally fiber-reinforced fiber-reinforced plastic.