JP2000251295A - Objective lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an objective lens driving device for suppressing the tangential tilt of an objective lens caused by the scattering of the dimension accuracy and the mounting position of an elastic support member or the like. SOLUTION: An objective lens driving device is provided with a lens holder 4 for retaining an objective lens 5 with a Z-axis direction as a light axis, an elastic support member 3 that is extended nearly in an X-axis direction as a whole being paired with a Y-axis direction and suspends and supports the lens holder 4 at a support member 1 so that it can travel in a Z-axis direction, permanent magnets 2a and 2b for drive that are arranged at the side of the support member 1 and have magnetic flux in the X-axis direction, and a focusing coil 7 that is fitted to the lens holder 4 while being wound around a Z-axis and has two opposing conductor parts 7a and 7b being extended in the Y-axis direction opposite to the permanent magnets 2a and 2b for drive. In this case, magnetic flux with different strength nearly in the X-axis direction is operated on the conductor parts 7a and 7b of the focusing coil 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compact disc (CD), a digital versatile disc (DV)
D) An objective lens driving device for driving an objective lens used for recording and reproducing information on a recording medium such as an optical disk such as an optical disk or a mini-disk (MD) in a predetermined direction. It is about.

[0002]

2. Description of the Related Art FIG. 9 is a perspective view of a conventional objective lens driving device. This objective lens driving device is a so-called four-wire supporting type moving coil system.
One end of each of the four elastic support members 3 made of a Be alloy, a Cu-P alloy, or the like is supported at a position separated by a predetermined interval, such as a vertex of a rectangle. These four elastic support members 3 extend in the tangential (X-axis) direction of a disc-shaped recording medium (not shown), and suspend and support the lens holder 4 at a free end which is the other end thereof. Objective lens 5 held by lens holder 4
Can be displaced in a tracking (Y-axis) direction crossing an information pit row (track) of the disk and in a focusing (Z-axis) direction substantially parallel to the optical axis of the objective lens 5.

In order to drive the objective lens 5 in the tracking direction and the focusing direction, the support member 1 has a substantially U-shape made of, for example, Fe, Ni, Co, an alloy containing them, or ferrite. The magnetic yoke 8 is placed in the opening 4a of the lens holder 4 so that the opposing legs face in the tangential direction.
The magnetic yoke 8 is provided, for example, with Nd so that different magnetic pole surfaces face each other via an air gap.
-Two drive permanent magnets 2a made of an Fe-B alloy or the like;
2b are provided respectively. Further, a tracking coil 6 for driving the objective lens 5 in the tracking direction is provided in the lens holder 4 so that the optical axis of the objective lens 5 is positioned on the center line of a predetermined track of the recording medium. And a focusing coil 7 for driving the objective lens 5 in the focusing direction in order to focus the objective lens 5 on the information pit surface. The driving permanent magnets 2a and 2b, the tracking coil 6 and the focusing coil are provided. 7 together form electromagnetic drive means.

Here, the focusing coil 7 is shown in FIG.
As shown in an exploded perspective view of FIG.
The tracking coil 6 is wound around the axis in the tangential direction on a plurality of protrusions formed on the bobbin 11 so as to project in the tangential direction. Two are formed. The bobbin 11 on which the tracking coil 6 and the focusing coil 7 are mounted has a conductor portion 7 a on one side extending in the tracking direction of the focusing coil 7 and a bobbin 11 extending in the focusing direction adjacent to the tracking direction of the two tracking coils 6. Existing conductive wire portion 6a and two driving permanent magnets 2a,
The lens holder 2 is fitted and fixed to the opening 4a of the lens holder 4 so as to be located in the facing gap.

[0005] In this manner, the two conducting wire portions 6a facing the driving permanent magnets 2a and 2b of the two tracking coils 6 are energized so that current flows in the same direction as the focusing direction. Conductor part 6a
The current flowing through the conductive wire portion 6a and the driving permanent magnet 2
The driving force in the tracking direction is generated by the interaction with the magnetic flux in the tangential direction by a and 2b to displace the lens holder 4 and thus the objective lens 5 in the tracking direction across the track of the recording medium (not shown). .

Similarly, when the focusing coil 7 is energized, a current flowing through the conductive wire portion 7a and a current flowing through the conductive permanent magnet 2a, 2b are applied to the conductive wire portion 7a extending in the tracking direction. The lens holder 4 generates a driving force in the focusing direction by interaction with the magnetic flux in the tangential direction by the lens holders 4a and 2b.
Eventually, the objective lens 5 is moved in a direction substantially parallel to its optical axis,
That is, the recording medium is displaced in a focusing direction substantially orthogonal to the recording surface of the recording medium (not shown).

[0007]

By the way, like the above-mentioned objective lens driving device, the lens holder 4 holding the objective lens 5 can be displaced in the tracking direction and the focusing direction via four elastic support members 3. In the case of suspension support on the support member 1, it is difficult to attach all the four elastic support members 3 to the same size in the assembling process, and to accurately attach them to symmetrical positions. For this reason, the translation error of the lens holder 4 is hindered by an assembly error of the four elastic support members 3. For example, when the lens holder 4 is moved in the focusing direction, the respective bending of the four elastic support members 3 is performed. A difference occurs in the state, and the lens holder 4 rotates around an axis parallel to the tracking direction, which may cause a tangential tilt of the objective lens 5 and tilt the optical axis.

As described above, when the optical axis of the objective lens 5 is tilted, various aberrations occur in the laser light spot irradiated on the disk-shaped recording medium, thereby lowering the reflection intensity and lowering the information reading signal level. And the occurrence of jitter and other phenomena, which tend to cause a problem that the S / N as the performance of the optical head is reduced. Such a problem becomes particularly significant as the recording density is improved and the pit length and the pit interval are shortened, which is a factor that hinders an increase in the recording density.

An object of the present invention has been made in view of such a conventional problem. The objective lens was driven in the focusing direction due to dimensional accuracy of the elastic support member, variation in the mounting position, and the like. It is an object of the present invention to provide an objective lens driving device that is appropriately configured so that tangential tilt of an objective lens with respect to a disk-shaped recording medium that occurs at the time can be effectively suppressed.

[0010]

In order to achieve the above object, the invention according to claim 1 comprises a lens holder for holding an objective lens having an optical axis in the Z-axis direction in an XYZ orthogonal coordinate system; A resilient support member extending generally in the X-axis direction as a whole and suspended and supporting the lens holder on the support member so as to be movable in the Z-axis direction; A driving permanent magnet having a magnetic flux, a focusing coil wound around the Z-axis and mounted on the lens holder, and having two opposing conductor portions extending in the Y-axis direction facing the driving permanent magnet; An objective lens driving device, characterized in that magnetic fluxes having different intensities substantially in the X-axis direction act on two opposing conductor portions of the focusing coil extending in the Y-axis direction. It is intended.

According to the objective lens driving device of the first aspect, since the magnetic fluxes having different intensities substantially in the X-axis direction act on two opposing conducting wire portions extending in the Y-axis direction of the focusing coil, When a current is applied to the focusing coil to drive the lens holder in the Z-axis direction, a rotational moment around the Y-axis is generated in the lens holder.
Therefore, this rotational moment is transferred to the lens holder Z
The tangential tilt of the objective lens with respect to the disk recording medium is made effective by generating it in the direction opposite to the rotation direction of the lens holder caused by the dimensional accuracy of the elastic support member and the variation of the mounting position when driven in the axial direction Can be suppressed.

According to a second aspect of the present invention, in the objective lens driving device according to the first aspect, a magnetic flux acting on one of two opposing conductor portions of the focusing coil extending in the Y-axis direction is adjusted. A magnetic piece is provided on the supporting member side so as to be able to approach or separate from the conducting wire portion.

As described above, if a magnetic piece is provided to adjust the magnetic flux acting on one of the conductors, it is possible to easily apply magnetic fluxes having different intensities to the two opposing conductors.

According to a third aspect of the present invention, in the objective lens driving device according to the first aspect, a magnetic yoke is provided so as to be coupled to the driving permanent magnet so as to adjust a magnetic resistance, and to adjust a magnetic resistance of the magnetic yoke. By doing so, the magnetic flux acting on one of the two opposing conductor portions extending in the Y-axis direction of the focusing coil is adjusted.

As described above, by adjusting the magnetic resistance of the magnetic yoke coupled to the driving permanent magnet, it is possible to adjust the magnetic flux from the driving permanent magnet that leaks from the magnetic yoke and acts on one conductor. Therefore, it is possible to easily apply magnetic fluxes having different intensities to the two opposing conductive wire portions.

According to a fourth aspect of the present invention, in the objective lens driving device of the first aspect, the magnetic flux acting on one of two opposing conductor portions of the focusing coil extending in the Y-axis direction is adjusted. An adjustment permanent magnet is provided on the support member side so as to be able to approach or separate from the conducting wire portion.

As described above, if the adjusting permanent magnet is provided to adjust the magnetic flux acting on one of the conductors, it is possible to easily apply magnetic fluxes having different strengths to the two opposing conductors. Become.

According to a fifth aspect of the present invention, in the objective lens driving device of the first aspect, the driving permanent magnet is disposed on the support member side so that the position in the X-axis direction can be adjusted, and the focusing coil is provided. Are arranged so that magnetic fluxes having different intensities substantially in the X-axis direction act on two opposing conductor portions extending in the Y-axis direction.

As described above, if the position of the driving permanent magnet in the X-axis direction can be adjusted, it is possible to easily apply magnetic fluxes having different intensities to two opposing conductive wires.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing a first embodiment of the present invention. This objective lens driving device is made of, for example, a Cu-Be alloy, a Cu-P alloy, or the like, extending in the tangential (X-axis) direction of a disc-shaped recording medium (not shown), as in the conventional example. One end of each of the four elastic support members 3 is
For example, the elastic members are connected to the support member 1 at predetermined intervals such as the vertices of a rectangle, and the free ends, which are the other ends of the four elastic support members 3, are connected to the lens holder 4.
The objective lens 5 held by the lens holder 4 is moved in a tracking (Y-axis) direction across the information pit row (track) of the disk-shaped recording medium and in a focusing (Z-axis) direction substantially parallel to the optical axis of the objective lens 5. Each is suspended and supported on the support member 1 so as to be displaceable.

Further, in order to drive the objective lens 5 in the tracking direction and the focusing direction, the support member 1 side penetrates into the opening 4a of the lens holder 4 and is made of, for example, an Nd-Fe-B alloy or the like. Drive permanent magnet 2
a and 2b are provided such that different magnetic pole surfaces face each other in the tangential direction with a gap therebetween. On the lens holder 4 side, a focusing coil 7 wound around an axis in the focusing direction and an axis around the tangential direction. A bobbin 11 made of resin or the like having two wound tracking coils 6 is provided, and driving permanent magnets 2a, 2b are provided.
And the tracking coil 6 and the focusing coil 7 constitute an electromagnetic driving means. In addition, the bobbin 11
As shown in the conventional example, one side of the conducting wire portion 7a extending in the tracking direction of the focusing coil 7,
The opening portion 4a of the lens holder 4 is arranged such that a portion of the conducting wire adjacent to the tracking direction of each of the tracking coils 6 and extending in the focusing direction is located in a space where the two driving permanent magnets 2a and 2b face each other. Fit and fix to.

In this embodiment, the supporting member 1 is provided outside the opening 4a of the lens holder 4 so as to face the conductor 7b on the opposite side of the conductor 7a of the focusing coil 7.
The magnetic piece 9 is provided on the side such that the distance from the conductive wire portion 7b can be adjusted by a detachable adjustment jig 10a.

According to this embodiment, the objective lens 5 can be moved in the tracking direction by energizing the tracking coil 6 in the same manner as described in the conventional example. On the other hand, when the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction. That is, since magnetic flux acts on the conductor portions 7a and 7b of the focusing coil 7 from substantially the same direction, when the focusing coil 7 is energized, the current direction is reversed in the conductor portions 7a and 7b. Generates a Lorentz force P1 and a reverse Lorentz force P2 occurs on the opposite side of the conducting wire portion 7b, so that a rotational moment M about the Y axis can be applied to the lens holder 4 and thus the objective lens 5. This makes it possible to tilt the optical axis of the objective lens 5 in the tangential direction. Moreover, the moment M can be adjusted by moving the magnetic piece 9 closer to or away from the conductor 7b by the adjustment jig 10a, thereby increasing or decreasing the magnetic flux linked to the conductor 7b.

Therefore, when assembling, the focusing coil 7 is energized to move the objective lens 5 by a predetermined amount in the focusing direction, and the adjusting jig 10a is operated in a direction to reduce the generated tangential tilt to position the magnetic piece 9. Is adjusted and fixed to the support member 1 side, and then the adjustment jig 10a is removed, whereby an objective lens driving device having excellent tangential tilt characteristics can be manufactured.

In this embodiment, two driving permanent magnets 2a and 2b are used. However, one driving permanent magnet, for example, only the driving permanent magnet 2a may be used. In addition, the magnetic piece 9 is provided in the opening 4a of the lens holder 4.
It can also be placed inside.

FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. This embodiment is different from the first embodiment in that two permanent magnets for driving 2a, 2b are mounted on the inner surfaces of both legs of a magnetic yoke 8 having a substantially U-shape coupled to the support member 1. In order to increase the magnetic efficiency of the substantially U-shaped magnetic yoke 8, its open end is closed by a return path member 8a made of a magnetic material to form an O-shaped magnetic path. The other configuration is the same as that of the first embodiment, and a duplicate description will be omitted.

Also in this embodiment, the objective lens 5 can be moved in the tracking direction by energizing the tracking coil 6 in the same manner as described in the conventional example. When the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction, as in the first embodiment. That is, the magnetic flux leaking from the magnetic circuit having the magnetic yoke 8 and the return path member 8a acts on the conducting wire portion 7b of the focusing coil 7 in substantially the same direction as the direction of the magnetic flux acting on the conducting wire portion 7a. 7
When a current is applied to the wire portion 7a, a Lorentz force P1 is generated in the wire portion 7a, and a Lorentz force P2 in the opposite direction is generated in the wire portion 7b on the opposite side.
, A rotational moment M about the Y axis can be applied to the objective lens 5, whereby the optical axis of the objective lens 5 can be inclined in the tangential direction. Moreover, the moment M can be adjusted by moving the magnetic piece 9 closer to or away from the conductor portion 7b by the adjusting jig 10a, thereby increasing or decreasing the leakage magnetic flux linked to the conductor portion 7b.

Therefore, similarly to the case of the first embodiment, when assembling, the focusing coil 7 is energized to move the objective lens 5 by a predetermined amount in the focusing direction, and to adjust and reduce the generated tangential tilt. By manipulating the tool 10a to adjust the position of the magnetic piece 9 and fixing it to the support member 1, the adjusting jig 10a is removed to manufacture an objective lens driving device having excellent tangential tilt characteristics. it can. In this embodiment, two drive permanent magnets 2a and 2b are used. However, as shown in FIG.
It can also be constituted only by a.

FIG. 4 is a schematic sectional view showing a third embodiment of the present invention. In this embodiment, instead of providing the magnetic piece 9 in the second embodiment, the bottom of a substantially U-shaped magnetic yoke 8 coupled to the support member 1 is formed as a return path member 8b which can be freely opened and closed. The open / close state of the return path member 8b is adjusted by a detachable adjustment jig 10b to adjust the magnetic resistance of the magnetic yoke 8. The other configuration is the same as that of the second embodiment, and a duplicate description will be omitted.

Also in this embodiment, the objective lens 5 can be moved in the tracking direction by energizing the tracking coil 6 in the same manner as described in the conventional example. When the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction, as in the above-described embodiment. That is, the magnetic flux leaking from the magnetic yoke 8 acts on the conducting wire portion 7b of the focusing coil 7 from substantially the same direction as the direction of the magnetic flux acting on the conducting wire portion 7a. Generates a Lorentz force P1 and an opposite direction Lorentz force P2 to the opposite conducting wire portion 7b, so that a rotational moment M about the Y axis can be applied to the lens holder 4 and thus the objective lens 5. Thereby, the optical axis of the objective lens 5 can be inclined in the tangential direction. In addition, the moment M is adjusted by opening and closing the return path member 8b by the adjusting jig 10b to change the magnetic resistance to change the magnetic efficiency, thereby increasing or decreasing the leakage magnetic flux linked to the conductor portion 7b. be able to.

Therefore, when assembling, the focusing coil 7 is energized to move the objective lens 5 in the focusing direction by a predetermined amount, and the adjusting jig 10b is operated in a direction to reduce the generated tangential tilt, so that the return path member 8b is moved. After adjusting the open / close state and fixing the support member 1 side, the adjustment jig 10b is removed, whereby an objective lens driving device having excellent tangential tilt characteristics can be manufactured. In this embodiment, the driving permanent magnet can also be only one permanent magnet 2a.

FIG. 5 is a diagrammatic sectional view of a main part showing a fourth embodiment of the present invention. This embodiment is different from the second embodiment in that, instead of providing the magnetic piece 9, the magnetic yoke 8 is drilled on the back surface of the driving permanent magnet 2 a, thereby exposing the driving permanent magnet from the magnetic yoke 8. A part of the magnetic cover 8 can be adjusted by using an adjustment jig 10b.
c to adjust the magnetic resistance of the magnetic yoke 8. The other configuration is the same as that of the second embodiment, and a duplicate description will be omitted. In addition,
FIG. 5 shows a sectional view of the YZ plane.

Also in this embodiment, the objective lens 5 can be moved in the tracking direction by energizing the tracking coil 6 in the same manner as described in the conventional example. When the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction, as in the above-described embodiment. That is, when the focusing coil 7 is energized, the conductive wire portion 7
The magnetic flux leaked from the magnetic yoke 8 is linked to b, and a Lorentz force P2 in a direction opposite to the Lorentz force P1 generated in the conductive wire portion 7a is generated, so that the lens holder 4 and the objective lens 5 around the Y axis are rotated. A rotational moment M can be applied, whereby the optical axis of the objective lens 5 can be inclined in the tangential direction. In addition, the moment M is adjusted by moving the magnetic cover 8c in the focusing direction by the adjusting jig 10b to adjust the area covering the rear surface of the driving permanent magnet 2a.
Can be adjusted by increasing or decreasing the leakage magnetic flux linked to the conductive wire portion 7b by changing the magnetic resistance.

Therefore, when assembling, the focusing coil 7 is energized to move the objective lens 5 by a predetermined amount in the focusing direction, and the adjusting jig 10b is operated in a direction to reduce the generated tangential tilt, thereby causing the magnetic cover 8c to operate. After adjusting the covering state of the drilled portion of the yoke 8 and fixing the magnetic cover 8c to the support member 1 side, the adjusting jig 10b is removed to manufacture an objective lens driving device having excellent tangential tilt characteristics. can do. In this embodiment, the driving permanent magnet can also be only one permanent magnet 2a.

FIG. 6 is a schematic sectional view showing a fifth embodiment of the present invention. This embodiment differs from the second embodiment in that the magnetic piece 9 is replaced by a permanent magnet 12 for adjustment, and the other configuration is the same as that of the second embodiment. In this embodiment, the adjustment permanent magnet 12 is arranged on the conducting wire portion 7b side of the focusing coil 7 with the magnetic pole opposite in polarity to the magnetic pole on the back side of the driving permanent magnet 2a.

Also in this embodiment, the objective lens 5 can be moved in the tracking direction by energizing the tracking coil 6 in the same manner as described in the conventional example. When the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction, as in the above-described embodiment. That is, since the magnetic flux mainly from the adjusting permanent magnet 12 acts on the conducting wire portion 7b of the focusing coil 7 from substantially the same direction as the direction of the magnetic flux acting on the conducting wire portion 7a,
When the focusing coil 7 is energized, a Lorentz force P1 is generated in the conducting wire portion 7a, and a Lorentz force P2 in the opposite direction is generated in the conducting wire portion 7b on the opposite side, so that the lens holder 4 and thus the objective lens 5 rotate around the Y axis. Rotational moment M
This allows the optical axis of the objective lens 5 to be inclined in the tangential direction. Moreover, the moment M can be adjusted by moving the adjusting permanent magnet 12 by the adjusting jig 10a to approach or isolate the conducting wire portion 7b, thereby increasing or decreasing the magnetic flux linked to the conducting wire portion 7b. Can be.

Therefore, when assembling, the focusing coil 7 is energized to move the objective lens 5 by a predetermined amount in the focusing direction, and the adjusting jig 10a is operated in a direction to reduce the generated tangential tilt, thereby adjusting the permanent magnet 12 for adjustment. After the position is adjusted and fixed to the support member 1 side, by removing the adjusting jig 10a, an objective lens driving device having excellent tangential tilt characteristics can be manufactured.

In this embodiment, also, the driving permanent magnet can be only one permanent magnet 2a. As shown in FIG. 7, the adjusting permanent magnet 12 may be arranged on the conducting wire portion 7b side of the focusing coil 7 with a magnetic pole having the same polarity as the magnetic pole on the back side of the driving permanent magnet 2a. In this case, the conducting wire portion 7b of the focusing coil 7 mainly includes the adjusting permanent magnet 12
When the focusing coil 7 is energized, Lorentz forces P1 and P2 are generated in the same direction in the conducting wire portion 7a and the conducting wire portion 7b, respectively. This makes it possible to apply a rotational moment M about the Y axis to the lens holder 4 and thus to the objective lens 5 to tilt the optical axis of the objective lens 5 in the tangential direction.
Therefore, for example, in FIG. 7, when the lens holder 4 has a tilt characteristic such that a clockwise tangential tilt occurs when the lens holder 4 is driven upward in the focusing direction, the offset is determined by the rotational moment M described above. Since the canceling can be performed, an objective lens driving device having excellent tangential tilt characteristics can be manufactured.

FIG. 8 is a schematic sectional view showing a sixth embodiment of the present invention. This embodiment is different from the second embodiment in that the magnetic yoke 8 on which the driving permanent magnets 2a and 2b are mounted can be adjusted in position in the tangential direction by a detachable adjusting jig 10c. The magnetic flux leaking from the magnetic yoke 8 acting on the conductive wire portion 7b is adjusted and fixed to the support member 1 side. The other configuration is the same as that of the second embodiment, and a duplicate description will be omitted.

Also in this embodiment, the objective lens 5 can be moved in the tracking direction by supplying electricity to the tracking coil 6 in the same manner as described in the conventional example. When the focusing coil 7 is energized, the objective lens 5 can be tilted in the tangential direction in addition to moving the objective lens 5 in the focusing direction, as in the above-described embodiment. That is, when the focusing coil 7 is energized, the conductive wire portion 7
The magnetic flux leaked from the magnetic yoke 8 is linked to b, and a Lorentz force P2 in a direction opposite to the Lorentz force P1 generated in the conductive wire portion 7a is generated, so that the lens holder 4 and the objective lens 5 around the Y axis are rotated. A rotational moment M can be applied, whereby the optical axis of the objective lens 5 can be inclined in the tangential direction. In addition, the moment M causes the magnetic yoke 8 to move in the tangential direction by the adjusting jig 10c, and acts on the conductive wire portion 7b of the focusing coil 7.
It can be adjusted by increasing / decreasing the leakage magnetic flux.

Therefore, when assembling, the focusing coil 7 is energized to move the objective lens 5 by a predetermined amount in the focusing direction, and the magnetic yoke 8 is adjusted in the direction to reduce the generated tangential tilt by the adjusting jig 10c.
By adjusting the position in the tangential direction by the operation described above and fixing it to the support member 1 side, and then removing the adjustment jig 10b, an objective lens driving device having excellent tangential tilt characteristics can be manufactured. In this embodiment, the driving permanent magnet can also be only one permanent magnet 2a. In addition, without using the magnetic yoke 8 or the return path member 8a, only the two driving permanent magnets 2a, 2b or one of the driving permanent magnets 2a are used, and the position in the tangential direction can be adjusted so as to be adjustable. It can also be configured to be fixed to.

[0042]

According to the present invention, magnetic fluxes having different intensities substantially in the X-axis direction are caused to act on two opposing conductor portions extending in the Y-axis direction of the focusing coil. When the lens holder is driven in the direction, a rotational moment about the Y axis can be generated in the lens holder, whereby the objective lens with respect to the disk recording medium caused by the dimensional accuracy of the elastic support member, the variation in the mounting position, and the like can be generated. A tangential tilt can be effectively suppressed, and a stable objective lens driving device can be provided.

[Brief description of the drawings]

FIG. 1 is a diagrammatic sectional view showing a first embodiment of the present invention.

FIG. 2 is a diagrammatic sectional view showing a second embodiment.

FIG. 3 is a schematic sectional view showing a modification of the second embodiment.

FIG. 4 is a schematic sectional view showing a third embodiment of the present invention.

FIG. 5 is a diagrammatic sectional view showing a fourth embodiment.

FIG. 6 is a schematic sectional view showing a fifth embodiment.

FIG. 7 is a schematic sectional view showing a modification of the fifth embodiment.

FIG. 8 is a schematic sectional view showing a sixth embodiment of the present invention.

FIG. 9 is a perspective view showing a conventional example.

FIG. 10 is a partially exploded perspective view of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support member 2a, 2b Permanent magnet for drive 3 Elastic support member 4 Lens holder 5 Objective lens 6 Tracking coil 7 Focusing coil 7a, 7b Conducting wire portion 8 Magnetic yoke 8a, 8b Return path member 8c Magnetic cover 9 Magnetic piece 10a, 10b, 10c Adjusting jig 12 Adjusting permanent magnet

Claims (5)

[Claims] 1. A lens holder for holding an objective lens having an optical axis in the Z-axis direction in an XYZ orthogonal coordinate system, and a lens holder extending in the X-axis direction generally as a pair in the Y-axis direction. An elastic support member suspended on a support member so as to be movable in the Z-axis direction, a drive permanent magnet disposed on the support member side and having a magnetic flux in a substantially X-axis direction, and wound around the Z-axis around the lens holder. A focusing coil having two opposing conducting wire portions extending in the Y-axis direction opposite to the driving permanent magnet, the objective lens driving device comprising: a focusing coil; An objective lens driving device, characterized in that magnetic fluxes having different intensities in a substantially X-axis direction are caused to act on two opposing conducting wire portions extending in a direction. 2. The support member side so as to be able to approach or separate from the conducting wire portion so as to adjust a magnetic flux acting on one of two opposing conducting wire portions extending in the Y-axis direction of the focusing coil. 2. The objective lens driving device according to claim 1, wherein a magnetic piece is provided on the object. 3. A magnetic yoke which is coupled to the driving permanent magnet and whose magnetic resistance is adjustable is provided. By adjusting the magnetic resistance of the magnetic yoke, two magnetic yokes extending in the Y-axis direction of the focusing coil are provided. 2. The objective lens driving device according to claim 1, wherein a magnetic flux acting on one of the opposing conductor portions is adjusted. 4. The support member side so as to be close to or separated from the conducting wire portion so as to adjust a magnetic flux acting on one of two opposing conducting wire portions extending in the Y-axis direction of the focusing coil. 2. The objective lens driving device according to claim 1, wherein an adjusting permanent magnet is provided in the apparatus. 5. The permanent magnet for driving is disposed on the support member side so that the position in the X-axis direction can be adjusted, and approximately two X-axis portions of the focusing coil extend in the Y-axis direction. 2. The objective lens driving device according to claim 1, wherein magnetic fluxes having different intensities in the axial direction act thereon.