JPH10149554A - Pickup lens braking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pickup lens braking device capable of effectively suppressing the unwanted displacement of the pickup lens and always precisely recording/reproducing information. SOLUTION: This device is constituted so that in a pickup lens driving device constituted so that a hold member 11 holding the pickup lens 8 is supported displaceably in the prescribed direction for a fixed member 10, and a driving coil 13 or a driving permanent magnet 14 is provided on the hold member 11, and the driving permanent magnet 14 or the driving coil 13 is provided on the fixed member, and the hold member 11 is made to be driven in the prescribed direction by an electromagnetic action between the driving coil 13 and the driving permanent magnet 14, a non-magnetic conductive part 31 is provided on the hold member 11 or the fixed member 10, and a braking permanent magnet 32 is provided on the fixed member 10 or the hold member 11 opposite to the non-magnetic conductive part 31 through a prescribed gap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pickup device for recording and / or reproducing information on an optical disk such as a compact disk (CD) and a digital video digital (DVD) and a recording medium such as a magneto-optical disk. The present invention relates to a braking device for a pickup lens.

[0002]

2. Description of the Related Art As a conventional pickup device, for example, one shown in FIG. 8 has been proposed. This pickup device is of a so-called rotating arm type, and has a base 1
The disk-shaped recording medium 3 is set on a shaft 2 of a spindle motor (not shown) provided on the base 1 and is rotated, and a rotating arm 4 rotatably provided on the base 1 is rotated. The optical pickup 5 provided at the tip is moved in a direction crossing the track of the disk-shaped recording medium 3.

Here, the disk-shaped recording medium 3 includes:
For example, a light-transmissive substance or a light-reflective substance is provided on the surface of a substrate made of a disc-shaped plastic or the like. CDs and DVDs are used.

The optical pickup 5 has a light emitting element 6, a beam splitter 7, a pickup lens 8, and a photodetector 9, as schematically shown in FIG. here,
The light-emitting element 6, the beam splitter 7, and the photodetector 9 are provided on a fixed member 10, and the pickup lens 8 is held on a holding member 11, for example, via a support member 12 having elasticity such as a wire or a leaf spring. The direction of the optical axis of the pickup lens 8 (focus direction) and the direction across the track of the disk-shaped recording medium 3 (tracking direction)
And is supported by the fixed member 10 so as to be displaceable.

Further, the pickup lens 8 is connected to the holding member 1.
1, the holding member 11 is provided with driving coils for a focus coil 13 and a tracking coil (not shown), and the fixed member 10 is provided with a magnetic field acting on these driving coils. The drive permanent magnet 14 is provided to perform the operation.

In this manner, the light from the light emitting element 6 is transmitted through the beam splitter 7 and is radiated to the disk-shaped recording medium 3 by the pickup lens 8 in the form of a spot, and the reflected light is transmitted through the pickup lens 8 to the beam splitter 7. The light is reflected by the optical detector 9 and received by the photodetector 9. Based on the output, the information recorded on the disk-shaped recording medium 3 is reproduced, and the focus error signal and the tracking error signal are detected. The detected focus error signal and tracking error signal are respectively supplied to the corresponding drive coils, so that the pickup lens 8 and the holding member 11 are moved together with the holding member 11 by the electromagnetic action with the magnetic field from the drive permanent magnet 14. By driving in the tracking direction, focus control and tracking control are performed such that a spot formed on the disk-shaped recording medium 3 always follows a desired track in a focused state.

[0007]

However, like the optical pickup 5 described above, the pickup lens 8 is held by the holding member 11 and is displaced in the predetermined direction via the support member 12 to the fixed member 10. In the supporting structure, when an inertia force such as vibration or impact is applied to the base 1 from the outside, the inertia force is transmitted to the pickup lens 8 via the support member 12, and particularly, When an inertial force corresponding to the frequency acts, the pickup lens 8 is displaced with a large amplitude, which causes a problem that focus control and tracking control become difficult. For this reason, a focus shift or a track shift of the pickup lens 8 occurs, so that information cannot be reproduced accurately. For example, when the information is used in a computer, a video, an audio device, or the like, a malfunction such as a malfunction is caused.

Although the case of reproducing information has been described above, the same problem occurs when information is recorded on a recording medium with the same configuration, and information cannot be accurately recorded.

An object of the present invention has been made in view of the above-mentioned conventional problems, and it is possible to effectively suppress an undesired displacement of a pickup lens, so that information can always be recorded and / or reproduced accurately. It is an object of the present invention to provide a pickup lens braking device appropriately configured as described above.

[0010]

In order to achieve the above-mentioned object, a pickup lens braking device according to the present invention supports a holding member for holding the pickup lens so as to be displaceable in a predetermined direction with respect to a fixed member. Providing a drive coil or a drive permanent magnet on the holding member, and providing a drive permanent magnet or a drive coil on the fixed member,
A non-magnetic conductive portion is provided on the holding member or the fixed member of the pickup lens driving device configured to drive the holding member in the predetermined direction by the electromagnetic action of the driving coil and the driving permanent magnet, A permanent magnet for braking is provided on the fixed member or the holding member so as to face the non-magnetic conductive portion via a predetermined gap.

The non-magnetic conductive portion may be formed by forming at least a part of the holding member or the fixing member with a non-magnetic conductive material, or may be formed by forming the holding member or the fixing member with a resin material. It is preferable to form a nonmagnetic conductor foil on at least a part of the surface in order to simplify the structure and reduce the weight of the movable part including the pickup lens and its holding member.

It is preferable that the braking permanent magnet be configured to also serve as the driving permanent magnet, since the configuration is simplified and the entire optical pickup is reduced in size.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS When a permanent magnet is opposed to a non-magnetic conductive part via a predetermined gap, a magnetic field generated by the permanent magnet penetrates the non-magnetic conductive part. The magnetic field by the permanent magnet penetrating the part changes. As described above, when the magnetic field penetrating the non-magnetic conductive portion changes, an eddy current flows in the non-magnetic conductive portion to suppress the magnetic field change according to the speed of the magnetic field change. An electromagnetic force, i.e., a repulsive force and an attractive force, is generated between the magnetic field generated by the permanent magnet and the permanent magnet, and the electromagnetic force acts to prevent relative displacement between the non-magnetic conductive portion and the permanent magnet.

For example, as schematically shown in FIG. 1, a non-magnetic conductive member 22 is arranged close to one magnetic pole surface (N-pole) of a permanent magnet 21, and the relative positional relationship between them is determined, for example, by the non-magnetic When the conductive member 22 is moved and changed in the same plane,
As shown by arrows, eddy currents flowing in the non-magnetic conductive member 22 in the opposite directions at the source and the destination are induced, and a magnetic field is generated by each eddy current.

The magnetic field generated in the non-magnetic conductive member 22 will be described in more detail. First, the permanent magnet 21 and the non-magnetic conductive member 22 arranged as shown in FIG.
Move to the positional relationship shown in FIG. 2B, a magnetic field is generated by a change in the magnetic field, that is, an eddy current induced according to their relative moving speed. The direction of the magnetic field is such that the magnitude of the magnetic field to which the nonmagnetic conductive member 22 was exposed before moving is compensated. For this reason, the source side repels the permanent magnet 21, and the destination side acts as a force that attracts the permanent magnet 21 to prevent the relative change due to the electromagnetic force that attracts the permanent magnet 21, and tries to return to the original position. I will be.

Further, as shown in FIGS. 3A and 3B, even when the permanent magnet 21 and the nonmagnetic conductive member 22 are relatively displaced in a direction approaching (or moving away from) each other, Since the eddy current is induced so as to maintain the magnetic field intensity to which the non-magnetic conductive member 22 has been exposed before, the braking action is also generated.

The magnetic field induced by such an eddy current increases as the displacement speed increases, so that a strong shock or vibration causes a rapid displacement, resulting in a strong braking force, which acts effectively. Become. The magnetic field induced by the eddy current acts as a braking force proportional to the relative displacement speed between the permanent magnet 21 and the non-magnetic conductive member 22, so that the braking force does not act in a stationary state.

Therefore, for example, the nonmagnetic conductive member 22
Is provided on the movable portion side including the pickup lens and its holding member, and the permanent magnet 21 is provided on the fixed member side supporting the movable portion, whereby the relative positional relationship between the nonmagnetic conductive member 22 and the permanent magnet 21 changes rapidly. When inertia force is applied,
Since an electromagnetic force is generated in the nonmagnetic conductive member 22 by an induced magnetic field that resists the inertial force, the displacement of the movable portion including the pickup lens can be reduced. Moreover, since the conductive member 22 is non-magnetic, for example, even if a driving coil is provided on the movable portion and a driving permanent magnet is provided on the fixed member side, the magnetic field generated by the driving coil and its change are not affected. Does not act at all, and the permanent magnet 2 for braking
1 and the attractive force of the driving permanent magnet which constitutes the electromagnetic driving means together with the driving coil.

That is, when the pickup lens is moved to a desired position by ordinary focus control or tracking control, even if there is a change in the magnetic field due to the drive coil, the nonmagnetic conductive member 22 is not affected by the change. In addition to being affected by the braking and driving permanent magnets, the relative movement speed between the nonmagnetic conductive member 22 and the permanent magnet is slow in normal focus control and tracking control. Therefore, an electromagnetic force that suppresses the displacement of the pickup lens does not act between the nonmagnetic conductive member 22 and the permanent magnet for braking. Therefore, it is not necessary to increase the driving force of the driving coil.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows a first embodiment of the present invention. In this embodiment, the pickup lens 8,
A non-magnetic conductive member 31 made of, for example, copper, aluminum, or gold is provided on a holding member 11 for holding a driving coil such as a focus coil 13 and the like, and is fixed to face the non-magnetic conductive member 31 via a predetermined gap. The braking device 33 is configured by providing a permanent magnet 32 for braking on the member 10. Other configurations are the same as those in FIG. 9, and components having the same functions as those in FIG.

In this embodiment, the non-magnetic conductive member 31
Is provided on the holding member 11, so that when an inertia force such as vibration or impact is applied from the outside, the pickup lens 8 moves in the same phase. On the other hand, since the braking permanent magnet 32 is provided on the fixed member 10, no relative displacement with respect to the recording medium due to inertial force occurs. Therefore, when an inertial force is applied to the pickup device, the non-magnetic conductive member 31 attempts to cause a relative displacement with respect to the medium together with the pickup lens 8, and an eddy current is generated in the non-magnetic conductive member 31 with the start of the relative displacement. Since the electromagnetic force is induced between the braking permanent magnet 32 and the induced permanent magnetic field against the inertial force, the displacement of the pickup lens 8 is suppressed to a small value.

Moreover, since the conductive member 31 is non-magnetic, it has no effect on the magnetic field or its change due to the driving coil, and the braking permanent magnet 32 and the driving permanent magnet 1
4 does not receive the suction force. That is, when the pickup lens 8 is moved to a desired position by normal focus control or tracking control, even if there is a change in the magnetic field due to the drive coil, the non-magnetic conductive member 31 is not affected by the change, and In addition to being affected by the permanent magnet 32 and the driving permanent magnet 14, the relative movement speed between the non-magnetic conductive member 31 and the braking permanent magnet 32 is slow in normal focus control and tracking control. Since no electromagnetic force acts to suppress the displacement of the pickup lens 8, it is not necessary to increase the driving force of the driving coil.

FIGS. 5A to 5D show examples of combinations of the positional relationship between the non-magnetic conductive member 31 and the braking permanent magnet 32 constituting the braking device 33 according to the present invention. FIG. 5 (A) shows that the non-magnetic conductive member 31 and the magnetic pole (N pole) of the braking permanent magnet 32 are arranged to face each other via a gap, and FIG. Permanent magnet 3
2 are arranged such that the magnetic poles face each other and the magnetic path is connected, and a non-magnetic conductive member 31 is provided between these two braking permanent magnets 32.
Is arranged. In FIG. 5B,
The other magnetic pole of each of the two braking permanent magnets 32 may be coupled to a ferromagnetic yoke material 35 or the like as indicated by a broken line to increase magnetic efficiency. FIG. 5C shows an arrangement in which the ends of both magnetic poles of the braking permanent magnet 32 are close to the side surface of the nonmagnetic conductive member 31.
(D) shows a non-magnetic conductive member 31 arranged so as to cover the braking permanent magnet 32.

FIG. 6 shows a second embodiment of the present invention. In this embodiment, the driving permanent magnet 14 is also used as the braking permanent magnet 32. Therefore, a non-magnetic conductive member 31 is provided on the holding member 11 so as to face the driving permanent magnet 14 with a predetermined gap therebetween. Other configurations are the same as those in FIG. Therefore,
According to this embodiment, in addition to the effects of the first embodiment, there is an advantage that the configuration can be simplified and the entire optical pickup 5 can be reduced in size because a permanent magnet dedicated to braking is not required.

FIGS. 7A and 7B show a third embodiment of the present invention. In this embodiment, the holding member 1
1 is formed of a non-magnetic conductive material, and a permanent magnet 32 for braking is provided on the fixed member 10 in opposition to the holding member 11 via a predetermined gap. Here, the holding member 11
Can be formed of a non-magnetic metal material such as copper or aluminum, or can be formed by kneading a conductive material such as graphite in a resin of a main material.

It should be noted that the present invention is not limited to the above-described embodiment, and that various modifications and changes are possible. For example, in the third embodiment, the entire holding member 11 does not necessarily need to be formed of a non-magnetic conductive material.
At least a portion under the influence of the braking permanent magnet 32 may be formed of a non-magnetic conductive material. In the same configuration as the third embodiment, a conductive material such as copper or gold is formed on the entire surface of the holding member 11 or a part under the influence of the braking permanent magnet 32 by plating to form a non-magnetic conductive material. Alternatively, the nonmagnetic conductive portion may be formed by providing a foil of copper, aluminum, gold, or the like instead of plating.

Further, in the above-described embodiment, the holding member 1
1, a driving coil was provided, and a fixed member 10 was provided with a driving permanent magnet 14. On the contrary, a holding member 11 was provided with a driving permanent magnet, and a fixed member 10 was provided with a driving coil. A permanent magnet for braking is provided on the holding member 11, a non-magnetic conductive part is provided on the fixing member 10, and various combinations are possible. When the holding member 11 is provided with driving and braking permanent magnets, and the fixed member 10 is provided with a driving coil and a non-magnetic conductive portion, the configuration described in the second and third embodiments, The configuration described in the above-described modification can also be effectively applied.

[0028]

According to the present invention, a non-magnetic conductive portion or a permanent magnet for braking is provided on a holding member for holding a pickup lens, which is supported so as to be displaceable in a predetermined direction with respect to the fixed member. Has a braking permanent magnet or a non-magnetic conductive portion facing a non-magnetic conductive portion or a braking permanent magnet provided on the holding member via a predetermined gap, so that the non-magnetic conductive portion and the braking permanent magnet are provided. When an undesired inertial force that changes the relative positional relationship with the magnet is applied, an electromagnetic force due to an induced magnetic field that resists the inertial force can be generated therebetween. Therefore, displacement of the pickup lens due to undesired inertial force can be suppressed to a small value, so that information can always be recorded and / or reproduced accurately.

Further, since the conductive portion is non-magnetic, it has no effect on the magnetic field or its change due to the driving coil.
Also, there is no attraction force due to the braking permanent magnet or the driving permanent magnet. Therefore, when the pickup lens is moved to a desired position by ordinary focus control or tracking control, even if there is a change in the magnetic field due to the driving coil, the non-magnetic conductive portion is not affected, and
It is not affected by the braking permanent magnet and the driving permanent magnet, and in normal focus control and tracking control, the relative movement speed between the non-magnetic conductive part and the braking permanent magnet is slow, and the pickup lens is located between them. Since no electromagnetic force acts to suppress the displacement of the driving coil, it is not necessary to increase the driving force of the driving coil.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 is also a diagram for explaining the principle.

FIG. 3 is a diagram for explaining the principle.

FIG. 4 is a diagram showing a first embodiment of the present invention.

FIG. 5 shows four examples of combinations of the positional relationship between the non-magnetic conductive member and the braking permanent magnet that constitute the braking device according to the present invention.

FIG. 6 is a diagram showing a second embodiment of the present invention.

FIG. 7 is a view showing a third embodiment.

FIG. 8 is a diagram for explaining a conventional technique.

FIG. 9 is a schematic diagram showing a configuration of the optical pickup shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 base 2 shaft 3 disk-shaped recording medium 4 rotating arm 5 optical pickup 6 light emitting element 7 beam splitter 8 pickup lens 9 photodetector 10 fixing member 11 holding member 12 support member 13 focus coil 14 driving permanent magnet 21 permanent magnet 22 Non-magnetic conductive member 31 Non-magnetic conductive member 32 Permanent magnet for braking 33 Braking device 35 Ferromagnetic yoke material

Claims (4)

[Claims] 1. A holding member for holding a pickup lens is supported so as to be displaceable in a predetermined direction with respect to a fixed member, and a driving coil or a driving permanent magnet is provided on the holding member, and the fixed member is driven. A pickup magnet driving device in which a driving permanent magnet or a driving coil is provided, and the holding member is driven in the predetermined direction by an electromagnetic action of the driving coil and the driving permanent magnet. A non-magnetic conductive part is provided on the fixing member, and a braking permanent magnet is provided on the fixing member or the holding member in opposition to the non-magnetic conductive part via a predetermined gap. . 2. The braking device for a pickup lens according to claim 1, wherein at least a part of the holding member or the fixing member is formed of a non-magnetic conductive material to constitute the non-magnetic conductive portion. 3. The non-magnetic conductive portion, wherein the holding member or the fixing member is formed of a resin material, and a non-magnetic conductive foil is formed on at least a part of a surface of the holding member or the fixing member. Item 2. A braking device for a pickup lens according to Item 1. 4. The apparatus according to claim 1, wherein the braking permanent magnet is also used as the driving permanent magnet.
4. The braking device for a pickup lens according to 2 or 3.