JPS61129744A - Two-dimension driver of optical system - Google Patents

Abstract

PURPOSE:To attain movement by a small torque by fixing an elastic support and an arm member prolonged to the opposite side to a turning support and providing the 2nd drive means to the arm member. CONSTITUTION:Plate springs 44, 45 are fixed to the upper and lower face of a bearing 21 at a nearly midpoint of the springs, one ends of the plate springs 44, 45 clip an objective leans holder 2 and a tracking coil 40 is fixed to the other end. The bearing 21 is fitted to a shaft 20 fixed to the base and engaged wit a projection 22 of the shaft 20 and a fastening race 23 to be turned freely around the shaft 20. In flowing a current to coils 9, 10 in response to a focus error signal, the objective lens 1 is displaced in the arrow (a) to apply focus servo keeping the distance between the objective lens 1 and the disc face properly. In flowing a current in response to a tracking error signal to the coil 40, the objective lens 1 is moved around the shaft 20 in the direction of arrow (b) to apply tracking servo.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a two-dimensional drive device for an optical system, and in particular to an optical information recording device, such as an optical disk device, an optical disk device, a digital audio device, etc. The present invention relates to a device for two-dimensionally driving an optical system such as an objective lens that focuses light onto a recording medium.

[Prior Art] Hereinafter, an explanation will be given taking an optical disk device as an example of an optical information recording device.

Generally, in an optical disk device, a width of 1~
Information pits with a length of 2 gm and a length of 1 to 3 JLm are recorded. To read information from the information pits, first a light beam (usually a laser beam) is focused on a spotless spot by an objective lens and irradiated onto the information pits. At this time, reflected light or transmitted light from the recording medium optically changes depending on the presence or absence of information pits. By detecting this change with a photodetector, a reproduced signal corresponding to the information pits can be obtained.

In such an optical disk device, it is extremely important that the minute spot always accurately scan the information pit array on the recording medium. To this end, autofocusing is required to correct focal shifts due to warpage of the recording medium, and autotracking is required to correct irradiation position shifts due to eccentricity of the recording medium.

Conventionally, as a method for realizing the autofocus and autotracking functions described above, a method using the effect of electromagnetic force caused by an electromagnetic coil and a magnet has been known.

(Conventional Example 1) A method in which an objective lens is supported by an elastic structure, and the elasticity of the structure allows the objective lens to be moved in the forcing direction and the tracking direction.

FIG. 3(A) is a plan view of a two-dimensional driving device for an objective lens using this method, and FIG. 3(B) is a side sectional view thereof.

The objective lens 1 is supported by an objective lens holder 2,
The upper and lower ends of the objective lens holder 2 are supported by leaf springs 3 and 4, respectively. The other ends of each of the leaf springs 3 and 4 are coupled via a relay plate 7 to the other ends of the leaf springs 5 and 8, each of which has one end fixed to the base body. The coils 8, 9, and 10 are fixed to the side surface of the objective lens holder 2, and their rigidity is increased by applying sufficient adhesive. yoke 1
1.12 and the magnetic field lines created by the permanent magnet 13 intersect the coil 8. Similarly, yoke 1
4.15, permanent magnet 1B and yoke 17.1B,
The magnetic field lines created by the permanent magnets 18 also intersect the coils 9 and 10, respectively.

The coil 8 is a tracking coil, and the position of the objective lens 1 is moved in the direction of the arrow by flowing a current according to the tracking error signal. In this way, tracking servo is performed that causes the minute spot to always follow the track on the disk surface.

On the other hand, the coils 8 and 10 are force-shinging coils, and the position of the objective lens I is moved in the direction of arrow a by flowing a current according to the focus error signal.

In this way, focus servo is performed to maintain an appropriate distance between the objective lens l and the disk surface.

(Conventional example 2) The objective lens holder holding the objective lens is rotatably attached to the support shaft and movably in the axial direction of the support shaft, so the objective lens can be moved in the force-singing direction and the tracking direction. How to do it.

FIG. 4(A) is a plan view of a two-dimensional driving device for an objective lens using this method, and FIG. 4(B) is a side sectional view thereof. However, if it is the same member as in Conventional Example 1, the same number will be given and the explanation will be omitted.

One end of the objective lens holder 30 holds the objective lens l, and the other end is fitted into a support @31 fixed to the base body. The objective lens holder 30 is rotatable about the support shaft 31 and movable in the axial direction.

The magnetic lines of force created by the cylindrical yokes 32, 33 and the permanent magnet 34 intersect with the force-shinging coil 35. By passing a current in accordance with the focus error signal through the coil 35, the objective lens 1 can be moved in the direction of the arrow a shown in FIG. 4(B), thereby adjusting the distance between the objective lens 1 and the disk surface appropriately. Focus servo is performed to maintain the focus.

Also, as in Conventional Example 1, by passing a current in accordance with the tracking error signal through the coil 8, the objective lens l
is moved in the direction of the arrow shown in FIG. 4(A), and tracking servo is performed.

The two conventional examples mentioned above are less likely to cause optical axis misalignment,
Compared to an auto-tracking method in which a light beam is deflected at a small angle by rotationally driving a movable mirror, this method has the advantage of stable autofocus operation.

[Problems to be Solved by the Invention] However, the drive device in Conventional Example 1 connects the two leaf springs 3 and 4 supporting the objective lens l to two separate leaf springs 5 and 4 via the relay member 7. 6, and these leaf springs 5 and 6 are fixed to the base body. For this purpose, the above-mentioned leaf springs 3, 4.5 and 6
This has a problem in that the optical axis of the light beam incident on the objective lens I and the optical axis direction of the objective lens I are likely to be tilted due to accumulation of twisting and assembly errors.

In order to solve this problem with conventional devices, it is necessary to use a leaf spring with as little twist as possible, and to adjust the assembly so that the optical axis of the light beam and the optical axis of the objective lens coincide. This results in complication of the assembly process.

The drive device in Conventional Example 2 has a problem in that when performing focus servo, a large force is required for driving in order to move the entire objective lens 1 and objective lens holder 30 in the direction of arrow a. . In general, since the support point is located at the end of the objective lens holder 30, twisting occurs at the fitting part, and a stick-slip phenomenon occurs when the objective lens holder 30 slides in the axial direction of the support shaft 31. It could happen.

[Means for Solving the Problems] A two-dimensional drive device for an optical system according to the present invention includes a first drive device that attaches an optical system to a rotating support via an elastic support, and moves the optical system in the optical axis direction. A two-dimensional drive device for an optical system that moves the optical system two-dimensionally by a drive means and a second drive means that rotates the rotary support, the rotary support having a second drive means extending to a side opposite to the elastic support. The invention is characterized in that the arm member is fixed, and the second driving means is provided on the arm member.

[Function] The optical system is two-dimensionally movable by the elasticity of the elastic support and the rotation of the rotary support, and the first drive means moves the arm member in the focus lens direction, and the second drive means moves the arm member. By rotating the rotary support body through the support body, it is possible to move the rotary support body in the tracking direction with a small driving force.

[Example 1 Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1(A) shows an embodiment of a two-dimensional/dimensional driving device for an optical system according to the present invention, and FIG. 1(B) is a side sectional view thereof. However, if it is the same member as the conventional example shown in FIG. W43 and FIG. 4, the same number will be given and the explanation will be omitted.

In FIG. 1, the leaf springs 44 and 45 are fixed to the upper and lower surfaces of the bearing 21 at substantially intermediate positions therebetween. Roughly speaking, one end of the leaf springs 44 and 45 holds the objective lens holder 2, and a tracking coil 40 is fixed to the other end. Also, yoke 41.42
And the magnetic lines of force created by the permanent magnet 43 intersect with the coil 40.

The bearing 21 is made of, for example, a low-friction material, is fitted onto a shaft 20 fixed to a base body, and is engaged by a convex portion 22 provided on the shaft 20 and a retaining ring 23 so as to be rotatable around the shaft 20. It has become.

Therefore, the objective lens 1 is movable in the direction of the arrow a by the elasticity of the leaf springs 44 and 45, and the axis 2
It is movable in the direction of the arrow with 0 as the center.

In the optical disk device using this embodiment having such a configuration, current flows through the coils 9 and 10 in accordance with the focus error signal, so that the objective lens 1 moves in the direction indicated by the arrow a.
Focus servo is performed to maintain an appropriate distance between the objective lens 1 and the disk surface. Also, coil 4
By passing a current corresponding to the tracking error signal through the lens 0, the objective lens l moves in the direction indicated by the arrow around the axis 20, and tracking servo is performed.

Note that, as shown in this embodiment, the coil 40 does not need to be located on the straight line connecting the objective lens 1 and the axis 20. Next, a modification will be described.

FIG. 2 is a plan view of another embodiment of the two-dimensional driving device for an objective lens according to the present invention. However, if the members are the same as those shown in FIG. 1, the same numbers will be given and the explanation will be omitted.

As shown in FIG. 2, the leaf springs 51 and 52 are bent at a desired angle (here, 45°) with respect to the straight line connecting the objective lens 1 and the axis 20, and the bending point is rotated about the axis 20. It is supported freely, and the objective lens holder 2 is fixed to one end and the coil 40 is fixed to the other end. The operation is similar to the previous embodiment.

In this way, the position of the trunking coil 40 can be selected to the extent that unnecessary force is not applied to the shaft 20,
Space can be used effectively.

Although an optical disk device is used as an example in this embodiment, it is of course not limited to this, and general optical information recording devices such as magneto-optical disk devices and digital audio devices, as well as object shape inspection devices can be used. It can be applied to optical devices such as flaw detection equipment. Furthermore, the present invention is not limited to driving only the objective lens, and the entire system including other optical elements or light sources may be driven.

〔Effect of the invention〕

As explained in detail above, since the two-dimensional driving device for an optical system according to the present invention has two leaf springs that support the optical system, the deviation of the optical axis due to twisting of the leaf springs as in Conventional Example 1 can be avoided. etc. will almost disappear.

Furthermore, the optical system is movable in the force direction due to the elasticity of the two leaf springs, and movable in the tracking direction by rotation of the rotation support.
The force required for driving is significantly smaller than conventional example 2,
Also, the stick-slip phenomenon is eliminated. therefore,
High-precision force steering and tracking control are possible.

Further, since the tracking coil and the force-shinging coil are arranged apart from each other, and the degree of freedom in arrangement is increased, the configuration is simple, downsizing is possible, and assembly is easy.

[Brief explanation of the drawing]

FIG. 1(A) is a plan view of an embodiment of a two-dimensional driving device for an optical system according to the present invention, FIG. 1(B) is a side sectional view thereof, and FIG. A plan view of another embodiment of a two-dimensional drive device. FIG. 3(A) is a plan view of a conventional example of a two-dimensional drive device for an optical system, and FIG. 3(B) is a side sectional view thereof. , FIG. 4(A) is a plan view of another conventional example of a two-dimensional drive device for an optical system, and FIG. 4(B) is a side sectional view thereof. 1...Objective lens 44.45, 51, 52...Plate spring 21...Bearing 9.10-...Four force shinging coil 40#111
1 Tracking coil agent Patent attorney Jo Taira Yamashita Figure 2 Figure 3 (A) Figure 3 (B) Figure 4 (A) Figure 4 (B)

Claims (1)

[Claims] (1) An optical system is attached to a rotating support via an elastic support, and the optical system is driven by a first driving means for moving the optical system in the optical axis direction and a second driving means for rotating the rotating support. In a two-dimensional drive device for an optical system that moves a system two-dimensionally, an arm member extending on the opposite side of the elastic support is fixed to the rotation support, and the second drive means is provided on the arm member. A two-dimensional drive device for an optical system characterized by the following.