JPS6334746A - Optical system driver - Google Patents

Abstract

PURPOSE:To optionally determine the spring constants of an elastic supporting member in two directions and to easily design an optical system supporting part of an optical system driving device by providing the elastic supporting member for supporting an optical system to be optionally moved with bending rigidity anisotropy in both focus and tracking directions. CONSTITUTION:A fixing member 22 for supporting and fixing an objective lens is fixed on a base 2 with a screw and one ends of four wires 24a, 24b, 26a, 26b having rectangular sectional shapes are fixed on the side of the fixing member 22 so as to exist in respective faces parallel with the X-Y face. Since an objective lens holding member 28 is fixed on the other ends of the wires 24a, 24b, 26a, 26b, these wires acts as objective lens supporting members. Since the sectional shapes of the wires 24a, 24b, 26a, 26b are rectangular, the sectional primary moments of the wires are changed in both the focus and tracking directions by changing the lengths of vertical and horizontal sides of the sectional shapes, so that the bending rigidity in respective directions can be optionally selected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is suitably used, for example, for driving an objective lens of an optical head in an optical information recording/reproducing apparatus. Optical system drive? Regarding cl.

[Prior Art] Conventionally, in an optical information recording/reproducing device, it is possible to focus a laser beam using an objective lens to form a minute spot on an information track of an information recording medium, and to scan the information track with the spot. It is done. However, the record
In order to perform accurate reproduction, it is necessary that the minute spot always follow the information track accurately in a sufficiently focused state. Therefore, in optical information recording and reproducing devices, the focusing state on the recording medium and the following state on the information track are constantly detected, and when these are about to deviate from the appropriate range, the objective lens Control is performed to move the lens and maintain proper focusing and tracking states.

This kind of focusing control and tracking control is
An objective lens is supported two-dimensionally movably, a focusing control coil and a tracking control coil are fixedly attached to the objective lens directly or indirectly, and the coils are placed in an appropriate steady magnetic field. This is done by controlling the passage 1a to each of the coils in accordance with the detection signals of the focusing state and tracking state.

Conventionally, as an objective lens driving device in the above-mentioned optical information recording/reproducing device, the objective lens is supported by a plurality of elastic wires, and the objective lens can be moved parallel to the focusing direction and also parallel to the tracking direction. A movable or movable objective lens drive device has been proposed.

[Problems to be Solved by the Invention] However, in such conventional objective lens drive S devices, the cross-sectional shape of the wire is circular.
The spring constant of the wire in each of the focusing direction and the tracking direction is fixed once the diameter and material of the wire are determined, and there is a drawback that the spring constant in each direction cannot be freely selected.

[Objective] The present invention has been made in view of the above-mentioned 1Fi1 problems of the prior art, and its purpose is to
Spring constants in the orcus direction and tracking direction can be freely determined. Optical system wJ movement? Our goal is to provide you with the best possible results.

[Means for Solving the Problems] According to the present invention, the above-mentioned object includes an optical system, a fixing member, and two non-parallel to each other having one end fixed to the optical system and the other end fixed to the fixing member. It has a supporting means made of a rod-shaped elastic member that can be bent and deformed in a direction, and a driving means for driving the optical system in at least two directions, and the rod-shaped elastic member has anisotropy in its bending rigidity. This is achieved by an optical system driving device having the following characteristics.

[Example] Hereinafter, optical system drive according to the present invention! An embodiment of the It position will be described specifically and in detail based on the drawings. In this embodiment, an objective lens will be used as an example of the optical system.

FIG. 1 is an exploded perspective view showing an embodiment of the optical system driving device according to the present invention, and FIG. 2 is an n-
It is an n' sectional view.

In FIGS. 1 and 2, reference numeral 2 denotes a board fixed to the main body of the apparatus, and the board is made of a ferromagnetic material such as electromagnetic soft iron. A through hole 4 is provided approximately in the center of the substrate 2 to ensure an optical path in the vertical direction. A cylindrical member 6 that can protrude upward is fixed around the through hole of the substrate 2.

Further, two permanent magnets 8 and 10 are bonded around the cylindrical member on the substrate z, and a plate-like member 12a having a bent portion 16 is placed on the permanent magnet 8. A plate member 12b is adhesively fixed on top of the plate member 12b. The portion of each plate-like member that corresponds to the cylindrical member 6 is formed into an arc 7iJ15 that is somewhat larger than the outer shape of the cylindrical member. In addition, one side of the bent portion 16 has two permanent magnets.
8.

20 are adhesively fixed so that they are parallel to each other and are spaced apart from each other by a predetermined pressure, facing in the vertical direction. The cylindrical member 6 and the plate members 12a and 12b are made of a ferromagnetic material similar to that of the substrate 2, and both act as a yoke for the magnetic circuit formed by the permanent magnets 8.10. The bent portion 16 also acts as a yoke for the permanent magnet 18.20.

A fixing member 22 for supporting and fixing the objective lens is also fixed with screws on the substrate z.

On the side surfaces of the fixing member are four wires 24a, 24b, each extending in a plane parallel to the x-y plane and having a rectangular cross-sectional shape as shown in FIG. 3(a).

One ends of 26a and 2Sb are fixed. still,
Each of the wires is insulated with rubber, resin, etc. As shown in the figure, the wires 24a and 24b are arranged so as to intersect when viewed from the Z direction, and are located at slightly different positions in the Z direction. (i.e., slightly separated in the vertical direction).

Wires 24a and 24b are equivalent, and in particular have substantially the same length and bending elasticity. In addition, the wires 24a and 24
b and are arranged symmetrically, intersecting each other at right angles at the center when viewed from two directions. The relationship between the wires 26a and 26b is the same as that between the wires 24a and 24b, and the wires 21ia and 26b have the same arrangement as the wires 24a and 24b when viewed from two directions.

An objective lens holding member 2 is fixed to the other ends of the wires 24a, 24b, 26a, and 26b, and thus the wires have the role of an objective lens supporting member. An objective lens 30 having an optical axis in the Z direction is fixedly held on the holding member, and the objective lens is located just above the through hole 4 of the substrate 2. A cylindrical coil 32 for focusing control is fixedly installed in the lower part of the objective lens holding member 28, and the lower end of the coil is just above the substrate 2 and is connected to the cylindrical member 6 and the plate members 12a, 12b.
It will be located between the arcuate portion 15 and the circular arc portion 15. Further, a flat coil 34 for tracking control is fixed to the Y-direction end face of the objective lens holding member 28, and the coil is positioned opposite the permanent magnet 18, 20. The two terminals of the force sink control coil 32 are electrically connected to the wires 24b and 26b, respectively, via a terminal plate 36 attached to the objective lens holding member 28. In addition, the tracking control coil 34
The two terminals are electrically connected to the wires 24a and 26a, respectively, via a terminal plate 38 attached to the objective lens holding member 2B. A terminal plate 40 is also attached to the fixed member 22 side, and output terminals of a focusing control drive circuit (not shown) are connected to the wires 24b and 26b via the terminal plate.
4a and 26a are connected to output terminals of a tracking control drive circuit (not shown).

Further, the objective lens holding means 28 includes a balance weight 4.
2 is attached, and the DJ node is set so that the center of gravity of the movable part including the holding means coincides with the point of application of the driving force during focusing and tracking control.

Next, the operation of the apparatus of this embodiment as described above will be explained.

Permanent magnet 8 above. Based on IO, in the magnetic circuit, a horizontal magnetic field exists between the cylindrical member 6 and the circular arc portions 15 of the plate members 12a and 12b, and a part of the focusing control coil 32 is located in the magnetic field. Therefore, by energizing the coil 32 from the focusing control drive circuit via the wires 24b and 26b, a vertical force is applied to the coil due to electromagnetic interaction with the magnetic field, thus holding the objective lens. The member 28 is moved vertically by a desired distance to perform focusing control. When moving this blade in one direction, wires 24a, 24b, and 26a are used.

26b is elastically deformed so that the objective lens holding member 28 moves in parallel without being tilted.

On the other hand, as shown in FIG.
The permanent magnets are arranged so that the polarity directions are opposite to each other in the Y direction, and these permanent magnets are arranged opposite to each other in the two vertical portions of the winding of the tracking control coil 34. , by energizing the coil 34 via the wires 24a, 26a from the tracking control drive circuit, the two perpendicular portions of the a-line will be energized by electromagnetic interaction with the magnetic fields produced by the permanent magnets 18, 20, respectively. A force in the X direction is applied to the coil, and thus the objective lens holding member 28 is moved horizontally by a desired distance S in the X direction, thereby performing tracking control. At this time, wires 24a, 24b, 26a,
26b is elastically deformed so that the intersection seen from the Z direction becomes approximately the center of rotation, and the objective lens holding member 28 rotates. According to the above structure, the wire 24a.

Since the cross-sectional shapes of the wires 24b, 28a, and 26b are rectangular, changing the lengths of the vertical and horizontal sides of the cross-sectional shapes changes the cross-sectional moment of inertia of the wires in the focusing direction and the tracking direction. Flexural rigidity can be freely selected.

In addition, in one or more embodiments, the cross-sectional shape of the wire was rectangular, but the present invention can obtain the same effect even if a wire having an elliptical cross-sectional shape is used as shown in FIG. 3(b). It will be done.

That is, by changing the lengths of the vertical and horizontal components in the cross-sectional shape of the wire, which has an elliptical cross-section,
The moment of inertia of the wire with respect to the focusing direction and the tracking direction changes, and the bending rigidity in each direction can be freely selected.

In addition, as another uninvented embodiment, even if the material of the wire is made of a fiber-reinforced plastic shade that has anisotropy in the vertical and horizontal directions, the focus direction and tracking direction of the wire Bending stiffness can be changed.

[9. Effect of Light] As explained above in detail and specifically, the present invention provides anisotropy in the bending rigidity in the focus direction and the tracking direction of the elastic support member that supports the optical system, which is a movable part. With this, the spring constants of the elastic support member in the two directions can be freely determined, thereby facilitating the design of the optical system support portion of the optical system drive device.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing an embodiment of an optical system drive device related to a wooden box, Fig. 2 is a sectional view taken along line n-n' in its assembled state, and Figs. 3 (a) and (b) are wires. Cross-sectional view. z2...fixing members 24a, 24b, 26a, 26b-=wire 28-...
Objective lens holding member 30...Objective lens Fig. 1 Fig. 2 Fig. 3 (b) Procedural amendment November 25, 1985 Commissioner of the Patent Office Black 1) Mr. Akio 1! Patent Application No. 61-176762 2 Name of the invention Optical system drive device 3 Relationship with the person making the amendment Name of patent applicant (100) Canon Co., Ltd. 4 Agent address 13 Toranomon 5-chome, Minato-ku, Tokyo No. 1 Toranomon 4o
Mori Building 6 Contents of the amendment (1) The scope of claims in the Memorandum of Understanding will be corrected as shown in the attached sheet. (2) On page 4, lines 3 and 4 of the specification, [supporting means consisting of a fixed rod-shaped elastic member capable of bending and deformation in two directions non-parallel to each other] is defined as "a plurality of fixed rod-shaped elastic members capable of bending and deforming". "Supporting means that is made up of members and supports the optical system movably in two directions." Claims: (1) The optical system comprises an optical system, a fixing member, and a plurality of bendable rod-shaped members having one end fixed to the optical system and the other end fixed to the fixing member. The rod-shaped elastic member has anisotropy in its bending rigidity, and the rod-shaped elastic member has anisotropy in its bending rigidity. An optical system drive device characterized by:

Claims (1)

[Claims] (1) An optical system, a fixing member, and a support means consisting of a rod-shaped elastic member that is capable of bending and deforming in two directions non-parallel to each other and whose one end is fixed to the optical system and the other end is fixed to the fixing member; and a driving means for driving the optical system in at least two directions, wherein the rod-shaped elastic member has anisotropy in its bending rigidity.