JPH09171630A - Objective support device for optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the device small-sized, reduce the displacement of an objective, and simplify the constitution by attracting a lens holder, connected to a fixed member through four wire bodies that are bent with almost no force, by a magnet and supporting it in a stationary state. SOLUTION: Different kind of objectives 2a and 2b are fixed to a lens holder 1 and a ferromagnetic body is embedded. The ferromagnetic body is attracted by the magnet 3 to make the wire bodies 5a-5d between the lens holder 1 and fixed member 6 sufficiently tensed, and the lens holder 1 becomes stationary. When a driving current for control is supplied to a focusing driving coil 7 or tracking driving coil 8, a force operates between the magnet 3 and the ferromagnetic body and the lens holder 1 is displaced in a focusing or tracking direction to adjust focusing or tracking.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens supporting device for an optical pickup used in an optical recording / reproducing apparatus for reading or writing information from an optical disc such as a CD (compact disc) or a DVD (digital video disc). It is a thing.

[0002]

2. Description of the Related Art Generally, in an optical pickup, an objective lens is provided in an optical axis direction (that is, a focusing direction) and a direction orthogonal to the optical axis direction (that is, a tracking direction).
It is necessary to movably support each of them. Conventionally, as this supporting device, a hinge type, a shaft sliding type, a four-wire type and the like are known.

By the way, as the hinge type, there are one having a first hinge that moves in the optical axis direction and a second hinge that is orthogonal to the optical axis, and one that supports an objective lens by an elastic body. , The former has a complicated structure, and the latter one displaces the objective lens against the elastic body,
This displacement is heavy, which requires a relatively large driving force. The axial sliding type has a complicated structure because the holder of the objective lens is inserted into the shaft and the focusing direction is rotated up and down along the axis and the tracking direction is rotated around the axis. Further, in the four-wire type, one end of each of four wires (a total of eight wires) is fixed at positions opposite to each other in the holder of the objective lens, and these wires are sufficiently stretched,
Since it supports the objective lens, the wire needs to be relatively long in order to sufficiently widen the displacement range of the objective lens, and there is a drawback that the device becomes large.

[0004]

As described above, in the conventional objective lens supporting device of the optical pickup, the structure thereof is complicated, the objective lens is displaced much, and it is difficult to downsize the device. There was a problem such as. In view of the above, it is an object of the present invention to provide an objective lens supporting device for an optical pickup that is compact, has a small displacement of the objective lens, and has a simple structure.

[0005]

In order to solve the above-mentioned problems and achieve the above-mentioned object, an objective lens supporting device of an optical pickup according to the present invention has an objective lens in the optical axis direction and in the optical axis direction. In an objective lens supporting device for an optical pickup, which supports each of them in a displaceable manner in orthogonal directions,
A fixed part fixed to the attachment target, a movable part fixed to the objective lens, and four linear bodies interposed between the fixed part and the movable part, wherein the optical axis direction is 2 One end is fixed to each of four points corresponding to the corners of the rectangle on the movable part whose sides are parallel and the other two sides are perpendicular to the optical axis direction, and the other end is the same as the rectangle. The four parts are fixed to four points corresponding to the corners of the square of the fixing part having the same shape as the square whose two sides are parallel to the optical axis direction, and each of the four has the same length. A linear body, a ferromagnetic body fixed to the movable part, and the ferromagnetic body is attracted without contacting the movable part including the ferromagnetic body,
A magnet is provided at a position where the four linear bodies are stretched so as to be substantially parallel to each other by this attraction.

The magnet may be in a fixed relationship with the fixed portion, and the magnet may also be used as a magnet for driving an objective lens. further,
A plurality of objective lenses may be fixed to the movable portion, and the movable portion may be displaced in a direction orthogonal to the optical axis direction to select the objective lens to be used, and the position of the magnet is moved. The movable portion may be displaced in a direction orthogonal to the optical axis direction, or a new air-core coil is provided, and when a driving current is passed through this coil, the coil and the magnet are separated from each other. The magnet may be moved by a force acting between them.

In addition, the mounting manner of the ferromagnetic body is such that the single ferromagnetic body is fixed over the entire surface of the rectangular parallelepiped lens holder serving as the movable portion facing the magnet. The ferromagnetic material is fixed near both ends in the optical axis direction, the ferromagnetic materials are fixed at four corners of the facing surface, and the single strong member near the central portion of the facing surface. The rod-shaped ferromagnetic bodies may be fixed in parallel to each other at positions corresponding to the vicinity of four corners of the facing surface on the two surfaces orthogonal to the facing surface for fixing the magnetic material.

[0008]

In the present invention configured as described above, when the ferromagnetic body fixed to the movable portion is attracted by the magnet, the attraction causes the four linear bodies to stretch,
These four linear bodies are substantially parallel to each other, and the movable part to which the objective lens is fixed can be displaced in the optical axis direction and the direction perpendicular to this direction.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a perspective view showing a state in which a drive coil described later is not wound, and FIG. 2 is a perspective view showing a state in which the drive coil is wound. 1 and 2, reference numeral 1 denotes a rectangular parallelepiped lens holder which is a movable portion, and two different types of objective lenses 2a and 2b are fixed to the lens holder 1. The objective lenses 2a and 2b are for CD and DVD,
As is well known, the disc is selected and used according to the disc to be used. A ferromagnetic body 4 is fixed to the lens holder 1 as shown by hatching in FIG. The ferromagnetic body 4 is composed of the objective lenses 2a and 2b.
Is embedded in a surface parallel to the optical axis direction and facing a magnet 3 to be described later so as to open a part thereof.

On the surface of the lens holder 1 opposite to the surface in which the ferromagnetic material 4 is embedded, the surface opposite to the optical axis direction is 2
Four points of the same length are respectively provided at four points which are parallel to each other and whose other two sides are perpendicular to the optical axis direction and which correspond to corners of a virtual square.
One ends of the linear members 5a, 5b, 5c, 5d of the book are fixed by adhesion or the like. The other ends of the linear bodies 5a to 5d are separated from each other by the optical axis direction as in the case of the rectangular shape.
Each side is fixed by adhesion or the like to four points corresponding to the corners of an imaginary square (a square or a rectangle as shown by the reference symbol B) in the fixing member 6 which is the fixing part and has the same shape as the above-mentioned rectangular parallelepiped. ing. As the linear members 5a to 5d, it is necessary to use almost no force to bend, for example, a copper wire having extremely low elasticity, a nylon wire used for fishing line, or a copper wire having extremely low elasticity coated with nylon. it can.

A focusing drive coil 7 and a tracking drive coil 8 are wound around the lens holder 1 as shown in FIG. Reference numeral 14 is a non-magnetic member, to which the magnet 3 is fixed and which has a fixed relationship with the fixing member 6.

The operation principle of the objective lens supporting device of the optical pickup constructed as described above will be described with reference to FIGS. 3 and 4. In the assembled state as shown in FIG. 2, the ferromagnetic body 4 is attracted by the magnet 3 as shown in FIG. 3, and the linear bodies 5a to 5d between the lens holder 1 and the fixing member 6 are sufficiently moved. It is in a stretched state,
The lens holder 1 is stationary. In this state, the linear members 5a to 5d are parallel to each other, and the lens holder 1 including the ferromagnetic member 4 has the magnet 3
Did not touch. In this state, when a drive current for control is supplied to the focusing drive coil 7 or the tracking drive coil 8, a force acts between the magnet 3 and the ferromagnetic body 4, and as is well known, the lens holder 1
Is displaced in the focusing direction or the tracking direction, and the focusing or tracking is adjusted.
The displacement in the tracking direction in this case is a parallel movement.

When a relatively large current for lens switching is applied to the tracking drive coil 8, the magnet 3 is moved.
The same force as described above acts between the magnetic field and the ferromagnetic body 4, and the lens holder 1 moves in parallel as shown in FIG.
The center of is the objective lens 2 of the optical system of this optical recording / reproducing apparatus.
It coincides with the optical axis relating to a and 2b (the position thereof is schematically shown by an imaginary line with reference numeral A in FIGS. 3 and 4). At the same time, by passing a relatively large current for lens switching through the focusing drive coil 7, the lens holder 1 is displaced and the distance of the objective lens 2a from the disc matches the disc used. . When the direction of the current passed through the tracking drive coil 8 is reversed from that described above, the center of the objective lens 2b coincides with the optical axis of the objective lenses 2a and 2b of the optical system of the optical recording / reproducing apparatus. , The lens holder 1 is moved in parallel.

When the lens switching current is cut off, the lens holder 1 returns to the state shown in FIG. 3. Therefore, when a disc is used by this optical recording / reproducing apparatus, the switching current in the direction corresponding to the disc is used. Is applied as a DC bias current to the focusing drive coil 7 and the tracking drive coil 8, and a control current (AC) for focusing or tracking drive is passed thereover to control the position of the objective lens 2a or 2b.

In the above-mentioned one embodiment, a relatively large bias current for switching lenses is required. In order to reduce this current, another embodiment shown in FIG.
And the one shown in FIG. 6 is also conceivable. 5 and 6, the same reference numerals as those in FIG. 2 indicate the same parts unless otherwise specified. In these drawings, reference numeral 3 is the magnet described above, which is rotatably attached to the two arms 10a and 10b rotatably attached to the second fixing member 9, respectively. It is provided so as to be movable in parallel to 9. The second fixing member 9 is fixed in a positional relationship parallel to the fixing member 6. Reference numeral 11 is an air-core coil, 12a and 12b are magnets or a ferromagnetic material such as ferrite, and 13a and 13b are shock absorbing materials, which are in a fixed relationship with the second fixing member 9.

With such a configuration, when switching the objective lenses 2a and 2b, instead of supplying a switching current to the tracking drive coil 8, the air core coil 11 is driven. Apply current for a short time. As a result, the force generated between the air-core coil 11 and the magnet 3 causes the magnet 3 to move in parallel as shown in FIG. 6, so that the magnet 3 is pulled by the ferromagnetic body 12a and pressed against the shock absorber 13a. It becomes a state. The state of FIG. 6 is maintained even if the drive current is interrupted. By thus moving the magnet 3 in parallel, the lens holder 1 having the ferromagnetic body 4 attracted by the magnet 3 also moves as shown in FIG. 6, and the objective is moved as in the case of FIG. The center of the lens 2a coincides with the optical axis of the objective lens 2a, 2b of the optical system of this optical recording / reproducing apparatus (the position is schematically shown by a virtual line with reference symbol A in FIGS. 5 and 6).

At the same time, by passing a relatively large current for lens switching through the focusing drive coil 7 in the same manner as described above, the lens holder 1 is displaced and the distance of the objective lens 2a from the disc is used. It will be suitable for the disc to be used. When the direction of the driving current flowing through the air-core coil 11 is reversed from the above, the magnet 3
Moves parallel to the opposite direction, and the center of the objective lens 2b comes to coincide with the optical axis. The shock absorbers 13a and 13b also serve as positioning purposes and are made of a non-magnetic material.

As the ferromagnetic body 4 fixed to the lens holder 1 described above, various modifications as shown in FIG. 7 can be considered. In FIG. 7, the left column shows the front face and the right column shows the side faces. (A) shows the ferromagnetic body 4 arranged on the front surface of the surface of the lens holder 1 facing the magnet 3 as in FIG. 1, and (b) shows a partial arrangement on both sides of the facing surface. (C) is arranged at four points close to the corners of the facing surfaces, (d) is arranged at the central portion of the facing surfaces, and (e) is the facing surfaces. It is attached on both sides orthogonal to each other,
In the case of (e), the rod-shaped ferromagnetic body 4 is used.

In the case of the above (a), since the magnetic flux from the magnet 3 can be received over the entire surfaces of the facing surfaces, the position of the lens holder 1 can be stably held. In addition, the materials (b) to (d) can reduce the weight of the ferromagnetic body 4. Then, in the case of (e), the distance that the magnetic flux of the magnet 3 passes through the inside of the ferromagnetic body 4 becomes long, the demagnetizing field coefficient of the ferromagnetic body 4 itself becomes small, and thus the demagnetizing force weakens, Since the deterioration of the force with which the ferromagnetic body 4 is attracted to the magnet 3 is prevented, the position of the lens holder 1 can be kept more stable. As the above-mentioned ferromagnetic material 4, iron or ferrite can be used.

In the above-mentioned embodiment, four linear members 5a to 5d, which hardly require bending force, are interposed between the lens holder 1 and the fixing member 6. These linear bodies 5a
5d to 5d, the lens holder 1 is displaced in the optical axis direction and in a direction orthogonal to the optical axis direction. However, the straight line passing through the virtual center of the lens holder 1 and the fixing member 6 is used as an axis for fixing the fixing member. It is also conceivable that the lens holder 1 rotates unnecessarily with respect to 6. As a countermeasure against this, except for both ends of the linear bodies 5a to 5d, the linear bodies are covered with pipes that are harder to bend than the linear bodies, or both ends of the linear bodies 5a to 5d are removed. It is conceivable that a resin or the like is attached to make it difficult to bend.

In the above embodiment, the lens holder 1 has two objective lenses 2a, 2 for CD and DVD.
Although b is fixed, the present invention can be applied to a case in which a larger number of objective lenses are fixed or a single objective lens for DVD or the like is fixed.

[0022]

Since the present invention is configured as described above, it is possible to obtain an objective lens supporting device for an optical pickup which can be miniaturized, has a small displacement of the objective lens, and has a simple structure.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a perspective view of a state before winding a coil.

FIG. 2 shows an embodiment of the present invention, and is a perspective view of a state after winding a coil.

FIG. 3 is a schematic plan view for explaining the operation of the embodiment of the present invention.

FIG. 4 is a schematic plan view for explaining the operation of the embodiment of the present invention, showing an operation state different from that in FIG.

FIG. 5 is a schematic plan view for explaining the operation of another embodiment of the present invention.

FIG. 6 is a schematic plan view for explaining the operation of another embodiment of the present invention, showing an operating state different from that in FIG.

FIG. 7 is a schematic diagram showing a modified example of the main part of the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens holder 2a, 2b Objective lens 3 Magnet 4 Ferromagnetic material 5a, 5b, 5c, 5d Linear body 6 Fixing member 7 Focusing drive coil 8 Tracking drive coil 9 Second fixing member 10a, 10b Arm 11 Air core Coil 12a, 12b Ferromagnetic material 13a, 13b Shock absorber 14 Non-magnetic member

Claims (11)

[Claims] 1. An objective lens supporting device of an optical pickup, which supports an objective lens so as to be displaceable in an optical axis direction and in a direction orthogonal to the optical axis direction, wherein a fixing portion fixed to an attachment target and an objective lens are provided. A movable part to be fixed, and four linear bodies interposed between the fixed part and the movable part, wherein two sides are parallel to the optical axis direction and the other two sides are the optical axis. One end is fixed to each of four points corresponding to the corners of the rectangle on the movable part perpendicular to the direction, and the other end has the two sides parallel to the optical axis direction like the rectangle. Fixed to four points corresponding to the rectangular corners of the fixed part having the same shape as the above, and four linear bodies having the same length and requiring almost no force for bending, and fixed to the movable part. The ferromagnetic material and the movable part including the ferromagnetic material without contacting And a magnet provided at a position where the four linear bodies are stretched so as to be substantially parallel to each other by the suction. apparatus. 2. The objective lens supporting device of the optical pickup according to claim 1, wherein the magnet is in a fixed relationship with the fixed portion. 3. The objective lens supporting device for an optical pickup according to claim 1, wherein the magnet is also used as a magnet for driving the objective lens. 4. The objective lens to be used is selected by fixing a plurality of objective lenses to the movable portion and displacing the movable portion in a direction orthogonal to the optical axis direction. 4. An objective lens supporting device for an optical pickup according to 1, 2, or 3. 5. The objective lens supporting device of the optical pickup according to claim 4, wherein the position of the magnet is moved to displace the movable portion in a direction orthogonal to the optical axis direction. 6. An air-core coil is provided, and the magnet is moved by a force acting between the coil and the magnet when a drive current is passed through the coil. Objective lens support device for the optical pickup of. 7. The single ferromagnetic body is fixed over the entire surface of the rectangular parallelepiped lens holder serving as the movable portion facing the magnet.
7. An objective lens supporting device for an optical pickup according to any one of 2, 3, 4, 5 and 6. 8. The ferromagnetic body is fixed to the surface of the rectangular parallelepiped lens holder serving as the movable portion facing the magnet in the vicinity of both ends in the optical axis direction. 7. An objective lens supporting device for an optical pickup according to any one of 3, 4, 5 and 6. 9. The ferromagnetic body is fixed to each of four corners on a surface of the rectangular parallelepiped lens holder which is the movable portion, the surface facing the magnet. 7. An objective lens support device for an optical pickup according to any one of 5 and 6. 10. A single ferromagnetic material is fixed near a central portion of a surface of the rectangular parallelepiped lens holder serving as the movable portion facing the magnet. 7. An objective lens support device for an optical pickup according to any one of 5 and 6. 11. The rod-shaped ferromagnetic body at a position corresponding to the vicinity of four corners of the facing surface in two surfaces orthogonal to the surface facing the magnet in the rectangular parallelepiped lens holder serving as the movable portion, Each of them is fixed in parallel to each other.
An objective lens support device for an optical pickup according to any one of 1.