JPH08335325A - Objective lens driving device - Google Patents

Abstract

PURPOSE: To prevent a lens holder from colliding with other parts due to external vibration by fixing the lens holder with attraction force or repulsion force between a driving magnet and a fixed magnet at the time of nonoperation. CONSTITUTION: At the time of nonoperation, an optical base is positioned 20b to be adjacent to the fixed magnet 22. In this case, the attraction force is generated between the driving magnet constituting a movable part and the fixed magnet 22. Then, the movable part is attracted in the direction of -Z, so that the lens holder is abutted against a base. Then, the movement of the lens holder in the direction of Z is fixed by the attraction force, while the movement in the directions of X and Y is fixed by friction between the lens holder and the base. Thus, the lens holder is prevented from colliding with other parts due to external vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device of an optical disk device for optically writing or reading information on a disk-shaped recording medium.

[0002]

2. Description of the Related Art Generally, currently used optical disk devices such as CD players and mini disk players rotate a disk at a predetermined number of revolutions, and a laser beam emitted from a laser diode is directed onto the disk by an objective lens. Collect light. The reflected light from the disc is converted into an electric signal by a photodetector, and the information recorded on the disc is reproduced. The objective lens driving device used for the optical disc device is designed to correct the objective lens with respect to the disc surface in order to correct the focus shift due to the vertical movement of the warp of the disc, the tracking shift due to eccentricity, etc. A vertical optical axis direction (hereinafter referred to as focus direction F) and a radial direction parallel to the recording medium surface (hereinafter referred to as tracking direction T)
It is driven on two axes.

An example of a conventional objective lens driving device will be described below with reference to the drawings. FIG. 6 is a perspective view of a conventional objective lens driving device. In FIG. 6, 102
Is a lens holder, and the objective lens 101, the focus coil 106, and the tracking coil 107 are fixed to form a movable portion. Reference numeral 109 denotes a support member, four of which are arranged substantially parallel to each other, and one end of which is the lens holder 1
02, and the other end is attached to the fixing member 108. The fixing member 108 is fixed to the yoke base 105. A magnet 103 is attached to the yoke base 105, and the two magnets 103 form two sets of magnetic circuits. The two sets of magnetic circuits generate magnetic flux in opposite directions in the Y direction shown in the figure. A yoke base 105 is fixed to an optical table 120 on which a laser diode and a photo detector (not shown) are mounted.

The operation of the objective lens driving device constructed as described above will be described below. In order to correct the focus shift due to the vertical movement of the warp of the disc and the tracking shift due to eccentricity, the objective lens is moved in the focus direction F (Z direction in the drawing) and the tracking direction T.
The operation of driving in two axes (X direction in the figure) will be described.

Driving in the focus direction F is obtained by a force in the focus direction generated when a current flows through the focus coil 106 due to the magnetic flux in the magnetic circuit, and translational movement is performed via the support member 109. Driving in the tracking direction T is obtained by causing a force in the tracking direction when a current flows through the tracking coil 107 due to the magnetic flux in the magnetic circuit, and performing a translational motion through the support member 109.

[0006]

However, in the above-mentioned conventional configuration, since no current flows in the focus coil and the tracking coil when the optical disk device is not operating, the movable part is free to deform within the range of deformation of the support member due to external vibration. Can move to. In recent years, optical disk devices have been widely used for portable applications, in-vehicle applications, etc., and there are increasing opportunities for external vibration when not in operation. If a large vibration or shock is applied from the outside, the movable part will have a yoke base. There is a risk of strong collision with a disc or disk and damage, or deformation of the support member.

The present invention solves the above problems, and an object of the present invention is to provide an objective lens driving device in which the components of the objective lens driving device and the disk are not damaged.

[0008]

In order to achieve the above object, the present invention provides a lens holder to which an optical system including an objective lens of a device for optically writing or reading information on a disk-shaped recording medium is attached, One end is attached to the lens holder and the other end is attached to the fixing member, and the lens holder is movably supported in the radial direction parallel to the recording medium surface of the disk-shaped recording medium and in the optical axis direction perpendicular to the recording medium surface. A support member, a base to which a fixing member is attached, a drive magnet attached to the lens holder, a yoke attached to the base, and a drive for the optical axis direction arranged in the air gap of the magnetic circuit including the drive magnet and the yoke. A coil, a drive coil for a radial direction, and a fixed magnet are provided.

[0009]

In the objective lens driving device having the above-described structure, the attraction force or the repulsive force generated between the driving magnet and the fixed magnet when the current does not flow in the optical axis driving coil and the radial driving coil Since the lens holder is fixed by, the lens holder does not collide with other parts due to external vibration.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. 1 is a perspective view showing the configuration of an objective lens driving device in a first embodiment of the present invention, FIG. 2 is a partial sectional view thereof, and FIG. 3 is a plan view and a front view thereof. FIG.
Further, in FIG. 2, reference numeral 2 denotes a lens holder, and the objective lens 1 and a driving magnet (or simply referred to as a magnet) 3 are fixed to form a movable portion. Reference numeral 9 denotes a support member, four of which are arranged substantially parallel to each other, one end of which is attached to the lens holder 2 and the other end of which is attached to the fixing member 8. The fixing member 8 is fixed to the base 10. A magnetic yoke (or simply called a yoke) 5 is embedded in a bobbin 4 mainly made of resin or the like. Reference numeral 6 is a focus coil as a drive coil for the optical axis direction, and 7 is a tracking coil as a drive coil for the radial direction. The tracking coil is wound around a bobbin 4 in which a magnetic yoke 5 is embedded,
Is fixed to the magnet 3 and forms two magnetic circuits with the magnet 3. The base 10 is fixed to an optical table 20 on which a laser diode and a photodetector (not shown) are mounted.

The operation of the objective lens driving device of this embodiment constructed as described above will be described below. In order to correct focus deviation due to vertical movement of warp of a disk-shaped recording medium (hereinafter referred to as disk) and tracking deviation due to eccentricity, the objective lens 1 is moved in the focus direction F (optical axis direction) and the tracking direction T (radial direction). ) The operation of driving on two axes will be described.

Driving in the focus direction F is performed by the objective lens 1.
The lens holder 2 to which the magnet 3 and the magnet 3 are attached is obtained by translating the magnetic yoke 5 around the focus coil 6 and the electrodynamic converter including the magnet 3 via the support member 9. The driving in the tracking direction T is performed by the lens holder 2 having the objective lens 1 and the magnet 3 attached, the magnetic yoke 5 around which the tracking coil 7 is wound, and the magnet 3.
It is obtained by translational movement through the support member 9 by an electrokinetic transducer consisting of

In FIG. 3, the optical stand 20 is driven along the guide shaft 21 in the X direction by a driving means (not shown). Further, the fixed magnet 22 is in a position where magnetic force such as attractive force or repulsive force does not act on the drive magnet 3 during operation of the optical disk device. When the optical disk device is in operation, the optical table 20 is at the position 20a and is separated from the fixed magnet 22, so that no attractive force is generated between the drive magnet 3 and the fixed magnet 22 which constitute the movable part. When not operating, the optical table 20 is at a position 20b close to the fixed magnet 22. At this time, the drive magnet 3 and the fixed magnet 2 which constitute the movable part
A suction force is generated between the lens holder 2 and the lens holder 2, and the movable portion is sucked in the −Z direction, and the lens holder 2 is pressed against the base 10. The movement of the lens holder 2 in the Z direction is fixed by a suction force,
The movement in the X and Y directions is fixed by the friction between the lens holder 2 and the base 10.

As described above, according to the present embodiment, when the focus coil 6 and the tracking coil 7 are in a non-operating state in which no current flows, the attraction force between the drive magnet 3 and the fixed magnet 22 causes the lens holder 2 to move. Since the lens holder 2 is fixed, it is possible to prevent the lens holder 2 from colliding with other parts due to external vibration, and it is possible to provide an objective lens driving device without damaging the parts or the disk.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a plan view and a front view showing the configuration of the objective lens driving device according to the second embodiment of the present invention. The difference between FIG. 4 and FIG. 3 is the arrangement of the fixed magnet 22. In the first embodiment, the attractive force between the drive magnet 3 and the fixed magnet 22 is generated in the Z direction, but in the present embodiment, the fixed magnet 22 is arranged at the position shown in FIG. A suction force is generated to fix the lens holder 2 when not operating.

As described above, according to this embodiment, as in the first embodiment, the lens holder 2 is fixed by the attractive force between the drive magnet 3 and the fixed magnet 22, so that the external vibration causes It is possible to prevent the lens holder 2 from colliding with other parts, and it is possible to provide an objective lens driving device without damaging the parts or the disk. The same effect can be obtained by changing the polarity of the fixed magnet 22 to generate repulsive force instead of attractive force.

The third embodiment of the present invention will be described below with reference to the drawings. FIG. 5 is a plan view and a right side view showing the configuration of the objective lens driving device in the third embodiment of the present invention. In FIG. 5, a long plate-shaped fixed magnet 2
It is the same as that described in the first embodiment in FIGS. 1, 2 and 3 except that 2 is fixed to the rod-shaped turning member 24a.

The operation of the objective lens driving device of the present embodiment constructed as described above will be described below. The operation of driving the objective lens in two axes of the focus direction F and the tracking direction T is the same as that of the first embodiment. The rotating member 24a (24b) rotates about the rotating shaft 25 in the direction of the arrow shown in the figure. During operation of the optical disk device, as shown by the rotating member 24a, the fixed magnet 22
Since a is located at a position away from the optical table 20, no attractive force is generated between the drive magnet 3 and the fixed magnet 22a that form the movable portion. During non-operation, the rotating member 24a is rotated by 180 degrees to the position shown by 24b by the driving means (not shown), and the fixed magnet 22a becomes the position of the fixed magnet 22b.
It is close to the optical table 20. Similar to the first embodiment, at this time, an attractive force is generated between the drive magnet 3 and the fixed magnet 22b forming the movable portion, the movable portion is attracted in the −Z direction, and the lens holder 2 is attached to the base 10. It is pressed and the movement of the lens holder 2 is fixed.

As described above, according to this embodiment, like the first embodiment, the lens holder 2 is fixed by the attractive force between the drive magnet 3 and the fixed magnet 22, so that the external vibration causes It is possible to prevent the lens holder 2 from colliding with other parts, and it is possible to provide an objective lens driving device without damaging the parts or the disk. Furthermore, according to this embodiment, the lens holder 2 can be fixed at an arbitrary position below the surface of the disc, so that it is not necessary to provide a fixing space in the optical disc device.

In this embodiment, the fixed magnet 22
The lens holder 2 has a long plate shape, but a short plate shape.
The fixed position of may be defined.

[0021]

As is apparent from the above description, according to the objective lens driving device of the present invention, when the drive coil for the optical axis direction and the drive coil for the radial direction are not energized, the drive magnet is Since the movable part composed of the lens holder and the like is fixed to the base by the attractive force or repulsive force with the fixed magnet, even if external vibration or shock is applied during transportation of the optical disk device, the component parts or the disk-shaped recording medium are It is possible to provide an objective lens driving device that is free from the risk of damaging the lens.

[Brief description of drawings]

FIG. 1 is a perspective view showing an objective lens driving device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an objective lens driving device in the example.

FIG. 3 is a plan view and a front view showing the configuration of the objective lens driving device of the embodiment.

FIG. 4 is a plan view and a front view showing the configuration of an objective lens driving device according to a second embodiment of the present invention.

FIG. 5 is a plan view and a right side view showing a configuration of an objective lens driving device according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing a conventional objective lens driving device.

[Explanation of symbols]

 1 Objective Lens 2 Lens Holder 3 Driving Magnet 4 Bobbin 5 Magnetic Yoke 6 Focus Coil 7 Tracking Coil 8 Fixing Member 9 Supporting Member 10 Base 22 Fixed Magnet

Claims (2)

[Claims] 1. A lens holder to which an optical system including an objective lens of an apparatus for optically writing or reading information on a disk-shaped recording medium is attached, and one end is attached to the lens holder and the other end is attached to a fixing member, A support member that supports the lens holder so as to be movable in a radial direction parallel to the recording medium surface of the disk-shaped recording medium and an optical axis direction perpendicular to the recording medium surface, and the fixing member are attached. A base, a drive magnet attached to the lens holder, a yoke attached to the base, a drive coil for the optical axis and a radial direction drive coil arranged in a gap of a magnetic circuit composed of the drive magnet and the yoke. A drive coil and a fixed magnet are provided, and when the device is not in operation, an attractive force or a repulsive force is generated between the drive magnet and the fixed magnet to operate. An objective lens driving device characterized in that an attractive force or a repulsive force is not generated between the drive magnet and the fixed magnet at times. 2. The objective lens drive according to claim 1, wherein a fixed magnet is provided at a position where magnetic force is not exerted on the drive magnet during operation of the device for writing or reading information on the disk-shaped recording medium. apparatus.