JPH11296881A - Damping device for optical head biaxial actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new structural damping device for an optical head biaxial actuator obtaining a stable damping effect without bringing a damping member into contact with a spring member, etc. SOLUTION: In the optical head biaxial actuator generating drive force in the intersected bizxial directions for a lens holder holding an objective lens displaceably hung/supported from/with a support member through the spring member, the damping device is constituted by providing a magnetic pole pair P arranged on one side of the support member and the lens holder, whose directions of magnetization are vertical to a plane containing the two axes and opposite to each other at intervals of nearly L-shaped boundary Bd orthogonally intersecting each of the two axes in a plane containing the tow axes and at least one of which consists of magnetic pole pair made of permanent magnet material, and a conductive member 23 opposite to the magnetic pole pair P through an air gap G and provided on the other side of the support member and the lens holder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a compact disc (CD), a digital versatile disc (DV)
The present invention relates to a vibration damping device used for an optical head biaxial actuator for recording and reproducing information on a recording medium such as an optical disk such as D) or a magneto-optical disk such as a mini disk (MD).

[0002]

2. Description of the Related Art As an optical head biaxial actuator having a conventional vibration damping device, for example, there is one shown in FIG. This optical head biaxial actuator has a so-called 4
This is a moving coil type of the wire support type, and extends substantially parallel to the X direction on the support member 1 through four spring members 3 made of, for example, a Cu-Be alloy, a Cu-P alloy, or the like. , Lens holder 4 holding objective lens 5
Are suspended and supported so as to be displaceable in a tracking (Y-axis) direction crossing a track of a disc (not shown) and a focusing (Z-axis) direction parallel to the optical axis of the objective lens 5.

As shown in detail in FIG. 9, a U-shaped soft magnetic yoke 8 made of, for example, Fe, Ni, Co, or an alloy containing these, or ferrite is provided on the support member 1 at both leg portions thereof. Are provided so as to face each other in the X direction and penetrate into the opening 4a of the lens holder 4. On the inner surfaces of both legs of the soft magnetic yoke 8, for example, Nd -A driving permanent magnet 2 made of an Fe-B alloy or the like is provided.
Further, the lens holder 4 is provided with a tracking coil 6 and a focusing coil 7 as driving coils in the opening 4a.

Here, the focusing coil 7 is formed by being wound around the bobbin 11, and the tracking coil 6 has a plurality of projections formed on the bobbin 11 so as to protrude in the X-axis direction. And two are formed by being wound in the shape of a figure. The bobbin 11 on which the tracking coil 6 and the focusing coil 7 are mounted has a conducting wire portion 7a on one side extending in the Y-axis direction of the focusing coil 7 and a z-direction adjacent to the two tracking coils 6 in the Y-axis direction. The extending conductive wire portion 6a is provided so as to fit in the opening 4a of the lens holder 4 so that the two driving permanent magnets 2 are located in gaps facing each other.

In such a configuration, when current is supplied to two conductor portions 6a facing the drive permanent magnet 2 of the two tracking coils 6 so that current flows in the same direction in the Z-axis direction, the conductor portions 6a A driving force in the Y-axis direction is generated by an electromagnetic interaction between the current flowing through the conducting wire portion 6a and the magnetic field oriented in the X-axis direction by the driving permanent magnet 2, whereby the lens holder 4 and thus the objective lens 5 are moved in the Y-axis direction. That is, it is possible to perform tracking control in which the optical axis of the objective lens 5 is made to follow the center of the track composed of the information pit array or the like by displacing the disk in a direction transverse to the track of the disc (not shown).

Similarly, when the focusing coil 7 is energized, a current flowing through the conductive wire portion 7a and the X-ray generated by the driving permanent magnet 2 are applied to the conductive wire portion 7a extending in the Y-axis direction facing the driving permanent magnet 2. Since a driving force in the Z-axis direction is generated by electromagnetic interaction with a magnetic field oriented in the axial direction, the lens holder 4 and thus the objective lens 5 are moved parallel to the Z-axis direction, that is, a direction perpendicular to the recording surface of the disc (not shown). And the focus control of moving the focus of the objective lens 5 to the recording surface on which the information pit row and the like are formed can be performed.

The above-described optical head biaxial actuator has a lens holder 4 having a so-called parallel spring structure.
To be driven. Therefore, for example, as compared with a so-called shaft-sliding type optical head, which is another typical driving method, in which a lens holder is rotatably supported with respect to an axis and is slidably supported and driven. Therefore, no friction occurs at the shaft portion when the lens holder 4 is driven, so that a smooth and high-resolution driving can be performed.

However, on the other hand, when viewed as a vibration system, the four spring members 3 correspond to sliding beams whose bending shape is an S-shape, and the lens holder 4 suspended and supported by these members corresponds to the additional mass at the tip. It has a configuration. For this reason,
On the other hand, it has the above advantages, but has a structure that easily vibrates violently as a linear vibration in the Y-axis direction, the Z-axis direction, or the YZ composite direction due to external vibration or impact, and further as a torsional vibration around the X-axis. .

In order to reduce such unwanted vibrations,
Usually, this type of optical head biaxial actuator is provided with a vibration damping device. For example, in the optical head biaxial actuator shown in FIG. 8, a gel pot 10 filled with a damping member 9 is provided near the fixed end of the spring member 3 to constitute a damping device. Vibration is absorbed. Here, the vibration damping member 9 is formed, for example, by filling a gel pot 10 with a silicone gel or the like having a large loss elastic modulus and then performing a curing treatment by irradiating ultraviolet rays, heating, or the like. Is appropriately set according to the resonance characteristics of the optical head.

As another conventional vibration damping device, for example, as shown in FIG. 10, a branch portion is formed at a position in the middle of bending near the support member 1 side of the spring member 3, and this branch portion and the main body portion are connected to each other. Are connected by a damping member 9 to obtain a damping effect. That is, in this vibration damping device, a rolled thin plate made of a similar alloy material or the like is patterned on the spring member 3 by etching or the like, and a linearly extending main body portion 30 and a branch portion 31 from a position in the middle of bending are formed.
And a branch portion 32 from a position fixed to the support member 1, and the main body portion 30 and the branch portions 31, 32 are formed of a similar material formed by sticking, dropping, printing, or the like. 9 are connected. Also in this case, the vibration damping member 9 is formed by curing treatment by irradiating ultraviolet rays, heating or the like, and its hardness, viscosity, and amount of formation are appropriately set according to the resonance characteristics of the optical head.

[0011]

However, in the above-mentioned conventional vibration damping device for a two-axis optical head actuator, the vibration damping member 9 is brought into direct contact with and coupled to the vibrating spring member 3 to thereby reduce the vibration damping effect. Therefore, there is a problem that the operation of the optical head biaxial actuator becomes unstable, as described below.

That is, as shown in FIG. 8, in a configuration in which the damping member 9 is used by injecting it into the gel pot 10,
It is difficult to accurately inject an appropriate amount of the damping member 9 into the gel pot 10 so that the damping member 9 has a predetermined depth.
Alternatively, due to variations in the processing time or the like, variations in the degree of crosslinking are likely to occur. For this reason, the filling amount varies among the spring members 3 used, a difference in hardness and a difference in viscosity occur, and the bendable length of each spring member 3 is different,
For this reason, when the lens holder 4 is driven in the focusing direction and the tracking direction, the amount of deflection of each spring member 3 becomes uneven, and the optical axis of the objective lens 5 is tilted.

Further, as shown in FIG.
In the configuration in which the main body portion 30 and the branch portions 31 and 32 are connected by the vibration damping member 9, the vibration damping member 9
It is extremely difficult to form an appropriate amount at a predetermined position by sticking, dropping, printing, or the like, and the degree of cross-linking after the formation is likely to vary. And a variation in the amount formed, and a difference in hardness is easily caused. For this reason, similarly, the bendable lengths of the spring members 3 are different from each other, so that the optical axis of the objective lens 5 is tilted.

As described above, when the optical axis of the objective lens 5 is tilted, side lobes are generated in the laser spot irradiated on the disk, so that crosstalk from an adjacent track is liable to occur, or a track offset is generated, resulting in appropriate tracking. Phenomena such as the inability to perform control and the decrease in the reflection intensity and the reproduction signal level occur, causing the problem that the S / N as the performance of the optical head is reduced.

Furthermore, these damping members 9 have a large aging effect such as aging of crosslinking due to a delayed reaction after completion of the curing treatment, and aging of hardness and loss elastic modulus. There is a problem.

An object of the present invention has been made in view of such a conventional problem, and has a novel structure capable of obtaining a stable damping effect without bringing the damping member into contact with a spring member or the like. An object of the present invention is to provide a vibration damping device for an optical head biaxial actuator.

[0017]

In order to achieve the above object, a vibration damping device according to the present invention includes a lens holder for holding an objective lens suspended and supported on a supporting member via a spring member so as to be displaceable. In an optical head biaxial actuator configured to generate a driving force in directions of intersecting two axes, each of the two axes is disposed on one side of the support member and the lens holder and in a plane including the two axes. The magnetizing direction is perpendicular to the plane including the two axes and opposite to each other across a substantially L-shaped boundary perpendicular to the magnetic pole, and at least one of the magnetic pole pairs is made of a permanent magnet material. , And a conductive member provided on the other side of the lens holder and the lens holder.

Further, the vibration damping device according to the present invention may be arranged such that, with respect to a lens holder holding an objective lens suspended and supported on a supporting member via a spring member, one side of the supporting member and the lens holder. In an optical head biaxial actuator configured to generate a driving force in two axial directions intersecting by electromagnetic driving means having a driving permanent magnet provided on a side surface different from the magnetic pole surface of the driving permanent magnet, The direction of magnetization is parallel to and opposite to the direction of magnetization of the driving permanent magnet across a substantially L-shaped boundary orthogonal to each of the two axes in a plane including the two axes; At least one of the magnetic pole pairs is made of a permanent magnet material, and a conductive member provided on the other side of the support member and the lens holder in opposition to the magnetic pole pair via a gap. The one in which the features.

In one embodiment of the present invention, the magnetic pole pairs are symmetrically arranged on opposing side surfaces different from the magnetic pole surfaces of the driving permanent magnet.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a main part of a first embodiment of the present invention. This vibration damping device is symmetrically arranged on opposite side surfaces different from the magnetic pole surface of the driving permanent magnet 20 having, for example, a width W and a height H as a magnetic pole surface, and moves the objective lens 5 in a focusing direction and a tracking direction described later. A substantially L-shaped boundary B orthogonal to each of the two axes that are the driving force generation directions for moving
Two pairs of magnetic poles P whose magnetization directions are parallel to and opposite to each other with the direction of magnetization of the driving permanent magnet 20 separated by d, and a gap G is formed between the driving permanent magnet 20 and the two sets of magnetic pole pairs P. And a conductive member 23 that is disposed to face through the conductive member 23. here,
At least one of the constituent members 21 and 22 of each magnetic pole pair P is made of a permanent magnet material.

In this embodiment, the constituent member 21 is made of a permanent magnet material and is integrally formed of the same material as that of the driving permanent magnet 20, and its magnetization direction is changed.
With the direction of magnetization. Also, the other component member 22
Is made of a soft magnetic material or a hard magnetic material magnetized in a direction opposite to that of the constituent member 21. When a soft magnetic material is used, the soft magnetic material is disposed adjacent to the constituent member 21 to be paired. The component 21 is magnetized in the opposite direction by the magnetic field. The driving permanent magnet 20 and the constituent member 21 are each formed of, for example, an Nd—Fe—B alloy, and the conductive member 23 is formed of, for example, Cu, Ag, Au,
In the case where a soft magnetic member is used, the component member 22 is made of Fe, Ni, Co or an alloy containing them, or a ferrite or the like. It is formed of an Nd—Fe—B alloy or the like. Further, the driving permanent magnet 20 can be used both as a dedicated magnetic field generating source for driving the optical head and as a dual-purpose magnetic field generating source for the vibration damping device.

In such a configuration, in each set of magnetic pole pairs P, when the constituent member 22 is formed of a soft magnetic material, the constituent member 22 is magnetized in the opposite direction by the paired constituent members 21 and the vicinity thereof is Since the magnetic field acts to converge the magnetic field in the space, the magnetic field penetrating the conductive member 23 changes abruptly near the boundary Bd of the magnetic pole pair P. Here, when the driving permanent magnet 20 and the magnetic pole pair P and the conductive member 23 are relatively displaced from each other, an eddy current is induced in the conductive member 23 to generate a braking force for suppressing the relative displacement. A large eddy current is generated in the portion facing the periphery of Bd due to a sudden change in the magnetic field, and as a result, a strong braking force is generated as a braking device, particularly in a direction orthogonal to the direction of the boundary Bd.

In each pair of magnetic pole pairs P, when the constituent member 22 is formed of a hard magnetic material magnetized in a direction opposite to that of the paired constituent member 21 and is disposed adjacent to the conductive member 23, In the vicinity of the boundary Bd of the magnetic pole pair P changes more rapidly. Therefore,
When the magnetic pole pair P and the conductive member 23 are relatively displaced from each other, a larger eddy current is generated in the conductive member 23, particularly in a portion facing the periphery of the boundary Bd.
A stronger braking force is generated in a direction orthogonal to the direction of d.

The conductive member 23 is connected to the driving permanent magnet 20.
It is also possible to use the permanent magnet for driving 20 as a dedicated magnetic field source for driving the optical head by deleting the permanent magnet at a position facing the optical head. Further, the driving permanent magnet 20 and the constituent member 21 of the magnetic pole pair P can be formed separately.

FIG. 2 shows an example of the configuration of an optical head biaxial actuator equipped with the vibration damping device shown in FIG. This optical head biaxial actuator includes a support member 1
Extend substantially in parallel in the X direction from the side, for example, C
Four spring members 3 made of a u-Be alloy, a Cu-P alloy, or the like are provided, and a lens holder 4 holding an objective lens 5 is suspended and supported on the free ends of these spring members 3. The objective lens 5 is configured to be displaceable in a tracking (Y-axis) direction and a focusing (Z-axis) direction, similarly to the conventional example shown in FIG.

On the support member 1 side, a U-shaped soft magnetic yoke 8 made of, for example, Fe, Ni, Co, or an alloy containing them, or ferrite, as in the conventional example shown in FIG. , With its legs facing in the X direction,
Provided so as to enter the opening 4a of the lens holder 4,
Driving permanent magnets 20 made of, for example, an Nd-Fe-B alloy are provided on the inner surfaces of both legs of the soft magnetic yoke 8 such that different magnetic pole surfaces face each other via a gap.
In order to constitute a vibration damping device by also using these drive permanent magnets 20, the magnetic pole pairs P described in FIG. 1 are provided symmetrically on both side surfaces in the Y-axis direction of each drive permanent magnet 20. Further, the lens holder 4 has two tracking coils and one focusing coil (not shown) wound around a bobbin 11 made of resin or the like on the inner surface of the opening 4a, similarly to the conventional example shown in FIG. A conductor portion adjacent to the two tracking coils in the Y-axis direction and extending in the Z-direction,
In addition to the one conducting wire portion extending in the Y-axis direction of the focusing coil, the two driving permanent magnets 20 are opposed to each other in such a manner that the two driving permanent magnets 20 are opposed to each other. Each driving permanent magnet 2 is located in the gap.
0 and the magnetic pole pair P on both sides thereof,
A conductive member constituting a vibration damping device is provided. Note that FIG.
In the above, the driving permanent magnet 20 and the two pairs of electrodes P are provided on the inner surfaces of both legs of the soft magnetic yoke 8, respectively. However, these may be provided only on the inner surface of one leg. Only the permanent magnet 20 may be provided with two magnetic pole pairs P.

In this configuration, when the tracking coil is energized, the tracking coil is driven in the Y-axis direction by the electromagnetic interaction between the current flowing in the Z-axis direction and the magnetic field oriented in the X-axis direction by the driving permanent magnet 20. When a force is generated and the focusing coil is energized, a driving force in the Z-axis direction is generated by an electromagnetic interaction between the current flowing in the Y-axis direction and the magnetic field oriented in the X-axis direction by the driving permanent magnet 20. That is, the optical head biaxial actuator includes a driving force in the Y-axis direction by a tracking coil for moving the objective lens 5 in the Y-axis direction, and a Z-axis by a focusing coil for moving the objective lens 5 in the Z-axis direction. A tracking control that generates a biaxial driving force with a driving force in the two directions and causes the optical axis of the objective lens 5 to follow the track center composed of the information pit train and the like, and the information pit train forms the focus of the objective lens 5 Focusing control for positioning on the recording surface that has been performed becomes possible.

In the optical head biaxial actuator shown in FIG. 2, when an external shock or vibration is applied, the spring member 3
Is generated together with the lens holder 4 in the Z-axis direction, Y-axis direction,
Attempts to start a large displacement in the synthesis direction or the rotation direction around the X axis. When such a phenomenon occurs, the drive permanent magnet 20 including the opposed magnetic pole pair P and the conductive member 2
The relative position with respect to the third side changes, and the magnetic field penetrating the conductive member 23 changes. In particular, the magnetic field changes abruptly in a portion facing the vicinity of the boundary Bd of the magnetic pole pair P. here,
The boundary Bd of the magnetic pole pair P is formed substantially in an L-shape in a plane including the two axes of the Z axis and the Y axis so as to be orthogonal to each of the two axes. It has a direction component orthogonal to any one of the boundaries Bd of the magnetic pole pairs P symmetrically arranged on both side surfaces of the permanent magnet 20.

Therefore, the eddy current induced by the change in the magnetic field flows through the conductive member 23 facing the driving permanent magnet 20 and the magnetic pole pair P, and particularly the conductive member 23 near the boundary Bd.
A large eddy current induced by a rapid change in the magnetic field flows through the magnetic pole pair P and the conductive member 23 due to the electromagnetic interaction between the eddy current and the magnetic field from the driving permanent magnet 20 and the component 21. A strong stopping force acts to prevent the relative displacement of. Moreover, such eddy currents
The higher the displacement speed is, the larger the displacement is. Therefore, the more the shock or vibration is applied and the more the displacement is generated, the stronger the stopping force becomes, and the more effective the action becomes. Therefore, the spring member 3
In addition to vibration suppression of so-called primary vibration having a large amplitude as in the case of flexural vibration, vibration can be effectively controlled not only for higher-order vibrations but also for resonances of a high frequency such as frame vibration of the lens holder 4. it can.

FIG. 3 shows the configuration of another example of an optical head biaxial actuator equipped with the vibration damping device shown in FIG. In this optical head biaxial actuator, four spring members 3 are extended from the support member 1 side to the lens holder 4 holding the objective lens 5 so as to become narrower in a plane parallel to the XY plane. The lens holder 4 is suspended and supported at the distal ends thereof.

On the support member 1 side, two U-shaped soft magnetic yokes 8 are arranged symmetrically with respect to the lens holder 4 at a distance from each other in a direction parallel to the Y-axis direction. Drive permanent magnet 20 magnetized in the Y-axis direction on the inner surface of the leg
And magnetic pole pairs P are provided on both side surfaces in the X-axis direction. Further, a bobbin made of resin or the like, in which a tracking coil and a focusing coil (not shown) are wound around the lens holder 4 in the same manner as in the conventional example shown in FIG. 11
In addition, a conductive member 23 is provided so as to face the driving permanent magnet 20 provided on each soft magnetic yoke 8 together with these coils and the magnetic pole pairs P on both sides thereof via a gap. In this manner, the driving device for the pair of objective lenses 5 and the pair of vibration damping devices are provided at the same location symmetric with respect to the ZX plane passing through the support center of the lens holder 4.

In this configuration, when the focusing coils of the pair of driving devices are energized, a driving force is generated in the Z-axis direction, and the lens holder 4 and the objective lens 5 are driven.
Can be moved parallel to the focusing direction,
When the tracking coils of the pair of driving devices are energized, driving forces parallel to the X axis are generated in opposite directions to rotate the lens holder 4 about an axis parallel to the Z axis. The lens 5 can be moved in the Y-axis direction, which is the tracking direction. That is, this optical head biaxial actuator includes a driving force in the X-axis direction by a tracking coil for moving the objective lens 5 in the Y-axis direction, and a Z-axis by a focusing coil for moving the objective lens 5 in the Z-axis direction. And a biaxial driving force.

Here, also in the optical head biaxial actuator shown in FIG. 3, an external impact or vibration is applied, and the spring member 3 is moved together with the lens holder 4 by, for example, resonance at the natural frequency of its bending deformation. When the displacement in the Z-axis direction, around the X-axis, around the Y-axis, or the like is started, the magnetic field penetrating the conductive member 23 changes. In particular, the magnetic field changes abruptly in a portion facing the vicinity of the boundary Bd of the magnetic pole pair P. Here, the boundary Bd of the magnetic pole pair P is defined by the Z axis and the X axis.
In a plane including the two axes, the two axes are formed in a substantially L shape so as to be orthogonal to each of the two axes, and the above-described vibration of the lens holder 4 is symmetrically arranged on both side faces of the driving permanent magnet 20. It has a direction component orthogonal to any one of the boundaries Bd of the magnetic pole pairs P.

Therefore, the eddy current induced by the change in the magnetic field flows through the conductive member 23 facing the driving permanent magnet 20 and the magnetic pole pair P, and particularly the conductive member 23 near the boundary Bd.
, A large eddy current induced by a rapid change in the magnetic field flows through the magnetic pole pair P due to the electromagnetic interaction between the eddy current and the magnetic field from the driving permanent magnet 20 and the component 21.
A strong stopping force acts to prevent relative displacement between the side and the conductive member 23 side.

According to the vibration damping device for the optical head biaxial actuator described above,
Strong vibration suppression is possible, and when driving the lens holder 4 in the focusing direction or the tracking direction, the spring member 3 can be uniformly bent and deformed.
Therefore, since the optical axis inclination of the objective lens 5 can be reduced, the occurrence of the side lobe of the laser spot can be effectively prevented, so that the crosstalk and the track offset from the adjacent track can be effectively reduced, and A decrease in reflection intensity can also be effectively prevented.

Further, since a stable material such as the magnetic pole pair P made of a hard or soft magnetic material and the conductive member 23 is used as the vibration damping device, the change with time is small.
A stable operation can be performed over a long period.

Further, since the vibration damping device can be provided, for example, in the width direction of the driving permanent magnet 20 in the tracking driving direction, the height of the optical head biaxial actuator for the vibration damping device can be increased. Nor.

FIG. 4 shows a configuration of a main part of a second embodiment of the present invention. In this embodiment, two-to-one pairs of magnetic pole pairs P are symmetrically arranged on opposing side surfaces different from the magnetic pole surfaces of the driving permanent magnet 20 having, for example, a width W and a height H as magnetic pole surfaces. That is, the magnetization direction of the driving permanent magnet 20 is separated by a substantially L-shaped boundary Bd orthogonal to each of two axes which are driving force generation directions for moving the objective lens 5 in the focusing direction and the tracking direction. Pole pairs P parallel and opposite to each other
Are symmetrically arranged on both side surfaces of the magnetic pole of the driving permanent magnet 20 as a two-to-one pair. Here, at least one of the constituent members 21 and 22 of each magnetic pole pair P is made of a permanent magnet material.

For this reason, in this embodiment, one component member 21 is integrally formed on each side surface of the magnetic pole of the driving permanent magnet 20 with the same material as the driving permanent magnet 20. The direction of magnetization is matched with the direction of magnetization of the driving permanent magnet 20. The other component member 22 is
Two each are made of a soft magnetic material or a hard magnetic material magnetized in a direction opposite to that of the constituent member 21.
In this way, two pairs of magnetic pole pairs P are provided on both side surfaces of the driving permanent magnet 20, respectively, and the conductive member 2 is provided between the driving permanent magnet 20 and the two magnetic pole pairs P via the gap G.
The vibration damping device is constituted by disposing the counter members 3 facing each other.

The vibration damping device configured as described above can obtain the same effects as those described above by being mounted on, for example, an optical head biaxial actuator having the structure shown in FIGS.

FIG. 5 shows a configuration of a main part of a third embodiment of the present invention. In this embodiment, for example, as shown in FIG. 4, two pairs of magnetic pole pairs are respectively provided on opposing side surfaces different from the magnetic pole surfaces of the driving permanent magnet 20 having the magnetic pole surfaces having the width W and the height H. P is arranged symmetrically. That is, the magnetization direction of the driving permanent magnet 20 is separated by a substantially L-shaped boundary Bd orthogonal to each of two axes which are driving force generation directions for moving the objective lens 5 in the focusing direction and the tracking direction. Are arranged symmetrically on both side surfaces of the magnetic poles of the driving permanent magnet 20 as a pair of magnetic pole pairs P which are parallel to each other and opposite to each other. Here, at least one of the constituent members 21 and 22 of each magnetic pole pair P is made of a permanent magnet material.

Therefore, in this embodiment, two constituent members 21 are integrally formed on both sides of the magnetic poles of the driving permanent magnet 20 with the same material as the driving permanent magnet 20, respectively. The direction of magnetization is matched with the direction of magnetization of the driving permanent magnet 20. The other component member 22 is
One each is made of a soft magnetic material or a hard magnetic material magnetized in a direction opposite to that of the constituent member 21.
In this manner, both sides of the driving permanent magnet 20 are
In contrast to the above, two pairs of magnetic pole pairs P formed so as to sandwich the structural member 22 by the structural member 21 are provided, and a gap G is provided between the driving permanent magnet 20 and the two magnetic pole pairs P.
A vibration damping device is configured by disposing the conductive member 23 to face each other via.

Therefore, the vibration damping device of this embodiment is also
For example, by mounting the optical head in a biaxial actuator having the configuration shown in FIGS. 2 and 3, the same effects as those described above can be obtained.

FIG. 6 shows a configuration of a main part of a fourth embodiment of the present invention. In this embodiment, two-to-one pairs of magnetic pole pairs P are symmetrically arranged on opposing side surfaces different from the magnetic pole surfaces of the driving permanent magnet 20 having, for example, a width W and a height H as magnetic pole surfaces. That is, the magnetization direction of the driving permanent magnet 20 is separated by a substantially L-shaped boundary Bd orthogonal to each of two axes which are driving force generation directions for moving the objective lens 5 in the focusing direction and the tracking direction. Pole pairs P parallel and opposite to each other
Are symmetrically arranged on both side surfaces of the magnetic pole of the driving permanent magnet 20 such that a frame-shaped boundary Bd is formed in a two-to-one pair. Here, the constituent members 21 and 22 of each magnetic pole pair P are:
At least one of them is made of a permanent magnet material.

For this reason, in this embodiment, the frame-shaped component members 2 are provided on both sides of the magnetic poles of the driving permanent magnet 20, respectively.
1 is formed integrally with the same material as the driving permanent magnet 20, and its magnetization direction is made to match the magnetization direction of the driving permanent magnet 20. The other component member 22 is provided inside the component member 21 with a soft magnetic material or a hard magnetic material magnetized in the opposite direction to the component member 21. In this manner, two pairs of magnetic pole pairs P are respectively provided on both side surfaces of the driving permanent magnet 20, and the conductive member 23 is connected to the driving permanent magnet 20 and the two magnetic pole pairs P via the gap G. A vibration damping device is configured by disposing them in opposition.

Therefore, the vibration damping device of this embodiment is also
For example, when the optical head is mounted on the optical head biaxial actuator having the configuration shown in FIGS. 2 and 3, the same effects as those described above can be obtained.

FIG. 7 shows a configuration of a main part of a fifth embodiment of the present invention. In this embodiment, for example, as in the case of FIG. 6, the objective lens is provided on both opposing side surfaces different from the magnetic pole surface of the driving permanent magnet 20 having the magnetic pole surfaces having the width W and the height H in the focusing direction and the tracking direction. The direction of magnetization is parallel to and opposite to the direction of magnetization of the driving permanent magnet 20 across a substantially L-shaped boundary Bd orthogonal to each of the two axes that are the driving force generation directions for moving the driving magnet 5. The magnetic pole pairs P are symmetrically arranged such that a frame-shaped boundary Bd is formed in pairs.

For this reason, in this embodiment, frame-shaped components 21 each made of a soft magnetic material are provided on both side surfaces of the magnetic poles of the driving permanent magnet 20, and inside the same direction as the driving permanent magnet 20. A component 22 made of a hard magnetic material magnetized is provided, and the component 21 is magnetized in the opposite direction by the magnetic field of the driving permanent magnet 20 and the component 22. In this manner, two pairs of magnetic pole pairs P are respectively provided on both side surfaces of the driving permanent magnet 20, and the conductive member 23 is connected to the driving permanent magnet 20 and the two magnetic pole pairs P via the gap G. A vibration damping device is configured by disposing them in opposition.

According to such a configuration, the magnetic field penetrating through the conductive member 23 is, as in the case of FIG.
, And according to this embodiment, the boundary Bdt between the driving permanent magnet 20 and the component member 21 is changed.
, The driving permanent magnet 20 and the magnetic pole pair P, and the conductive member 23 attempt to make relative displacement with each other. In particular, the conductive member 23 has a boundary Bd and a boundary Bdt, respectively. A large eddy current is generated in the opposing peripheral portion, so that the braking device generates a strong braking force, particularly in a direction perpendicular to the boundary Bd and in a direction perpendicular to the boundary Bdt. Therefore, if such a vibration damping device is mounted on, for example, an optical head biaxial actuator having the configuration shown in FIGS. 2 and 3, in addition to the above-described vibration damping action, it is particularly effective for vibration in a specific direction, for example, tracking direction. A vibration damping action can be exerted.

It should be noted that the present invention is not limited only to the above-described embodiment, and various modifications or changes can be made. For example, the vibration damping device according to the present invention is not limited to the optical head biaxial actuator having the configuration shown in FIGS. 2 and 3, and various other optical head biaxial actuators having a suspension support structure using a spring member, for example, The present invention can be effectively applied to a moving magnet type optical head biaxial actuator in which a driving coil is disposed on the member 1 side. Further, the width, height and thickness of the constituent members 21 and 22 of the magnetic pole pair P do not need to be the same as those of the driving permanent magnet 20, and may vary depending on the size of the optical head biaxial actuator to be mounted. It can be changed as appropriate for the purpose of adjusting the braking force of the vibration damping device to a desired magnitude or the like. Further, the constituent members 21 and 22 of the magnetic pole pair P may be connected by a soft magnetic material or the like on the back surface facing the conductive member 23 so as to increase the magnetic efficiency as the magnetic pole pair.

Further, in each of the above-described embodiments, the magnetic pole pairs are provided on both sides opposite to the magnetic pole surface of the driving permanent magnet of the optical head biaxial actuator, but the magnetic pole pairs are provided only on one side. Can also. Furthermore, the magnetic pole pair does not necessarily need to be provided on the side different from the magnetic pole surface of the driving permanent magnet, and can be provided at an arbitrary position on one side of the lens holder and the supporting member supporting the lens holder. In addition, a conductive member may be provided on the other side of the lens holder and the support member facing the magnetic pole pair to form a vibration damping device.

[0052]

According to the vibration damping device of the present invention, in the plane including the two axes intersecting the driving force generation direction of the optical head two-axis actuator, the L-shape is substantially orthogonal to each of the two axes. A pair of magnetic poles whose magnetization directions are perpendicular to the plane including the two axes and are opposite to each other are provided on one side of the lens holder and the supporting member that supports the lens holder. The conductive member is provided on the other side of the lens holder and the support member in opposition to each other, so that strong vibration suppression in various directions can be performed without contacting the spring member. When the lens is driven in the focusing direction or the tracking direction, the spring member can be uniformly bent and deformed. Therefore, the occurrence of side lobes in the laser spot can be effectively prevented, so that crosstalk and track offset from adjacent tracks can be effectively reduced, and a decrease in reflection intensity can be prevented. Reduction can be effectively prevented.

Further, since a stable material such as a magnetic pole pair and a conductive member made of a hard or soft magnetic material is used as the vibration damping device, the change with time is small and stable operation can be performed for a long period of time. .

Further, if the magnetic pole pairs constituting the vibration damping device are provided, for example, in the width direction of the driving permanent magnet of the optical head biaxial actuator, the height of the optical head biaxial actuator can be increased. Instead, a vibration damping device can be mounted.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an example of an optical head biaxial actuator on which the vibration damping device shown in FIG. 1 is mounted.

FIG. 3 is a perspective view showing a configuration of another example.

FIG. 4 is a perspective view illustrating a configuration of a main part of a second embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a main part of the third embodiment.

FIG. 6 is a perspective view showing a configuration of a main part of the fourth embodiment.

FIG. 7 is a perspective view showing a configuration of a main part of the fifth embodiment.

FIG. 8 is a view for explaining a conventional vibration damping device for an optical head biaxial actuator.

9 is a partially exploded perspective view of the optical head biaxial actuator shown in FIG.

FIG. 10 is a diagram for explaining another conventional vibration damping device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support member 3 spring member 4 lens holder 5 objective lens 8 soft magnetic yoke 11 bobbin 20 driving permanent magnet 21, 22 constituent member of magnetic pole pair 23 conductive member Bd boundary of magnetic pole pair P magnetic pole pair

Claims (3)

[Claims] An optical head biaxial actuator for generating a driving force in a biaxial direction intersecting a lens holder holding an objective lens suspended and supported on a supporting member via a spring member so as to be displaceable. In one aspect, the direction of magnetization is disposed on one side of the support member and the lens holder, and the direction of magnetization is separated by a substantially L-shaped boundary orthogonal to each of the two axes in a plane including the two axes. A pair of magnetic poles that are perpendicular to each other and that are opposite to each other, and at least one of which is made of a permanent magnet material, and is provided on the other side of the support member and the lens holder so as to face the magnetic pole pair via a gap. A vibration damping device for an optical head biaxial actuator, comprising: a conductive member; 2. A drive permanent magnet provided on one side of the support member and the lens holder with respect to a lens holder for holding an objective lens suspended and supported on a support member via a spring member so as to be displaceable. In an optical head biaxial actuator configured to generate a driving force in directions of two axes intersecting with each other by an electromagnetic driving unit, the optical head biaxial actuator is arranged on a side different from a magnetic pole surface of the driving permanent magnet, and in a plane including the two axes. A magnetic pole whose direction of magnetization is parallel to and opposite to the direction of magnetization of the driving permanent magnet across a substantially L-shaped boundary orthogonal to each of the two axes, at least one of which is made of a permanent magnet material An optical head biaxial actuator comprising: a pair; and a conductive member provided on the other side of the lens holder in opposition to the magnetic pole pair via a gap. Eta of the vibration damping device. 3. The vibration damping device for an optical head biaxial actuator according to claim 2, wherein said magnetic pole pairs are arranged symmetrically on opposite side surfaces different from the magnetic pole surfaces of said driving permanent magnets.