JPH0233333Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a feeding device in which an optical pickup in various optical devices is moved by a linear motor.

BACKGROUND TECHNOLOGY AND PROBLEMS In order to provide high reliability, high response, etc. to a feeding device for an optical pickup, a feeding device to which a linear motor is applied has been considered.

FIG. 1 shows a conventional example of the above-mentioned feeding device in an optical disk device. In this optical disk device 1, a housing 3 of an optical pickup 2 is formed of aluminum die-casting. This housing 3 is slidably supported by two feed shafts 4 that pass through it so that the pick-up 2 can be fed in the radial direction of an optical disk (not shown).

The thrust for moving the housing 3 along the feed shaft 4 is obtained by a linear motor 5. The linear motor 5 includes a yoke 6 extending near the feed shaft 4 and along the feed shaft 4, two magnets 7 disposed within the yoke 6 so as to extend along the feed shaft 4, and two magnets 7. It has a coil 11 which is a secondary conductor and is arranged between the magnets 7.
The coil bobbin 12 of the coil 11 is slidably supported by a part of the yoke 6 and is movable in the direction of the feed shaft 4. Further, one end portion 12a of the bobbin 12
is mechanically joined to one side of the housing 3.

Therefore, when the coil 11 is energized, the coil 11 generates a thrust in the direction of the feed shaft 4, so the casing 3 and the pick-up 2, which are joined to the bobbin 12, receive the thrust in the direction of the feed shaft 4, and the pick-up 2 to a predetermined position.

However, in the optical disk device 1 as described above, the casing 3 of the pickup 2 and the linear motor 5 serving as its feeding device are constructed as separate devices. For this reason, both of them occupy a large space, making it difficult to downsize the optical disk device 1.

Furthermore, since the housing 3 of the pick-up 2 and the linear motor 5, which are separate devices, are mechanically connected, the center of gravity of the pick-up 2 and the housing 3 and the center of the thrust-generating portion of the linear motor 5 are aligned. They are widely separated. For this reason, twisting and deflection occur in the coil 11 of the linear motor 5 and the joint between the linear motor 5 and the housing 3, and these twists and deflections cause the housing 3 and the linear motor to 5
Dynamic resonance occurs between the two, and the feed operation of the pick-up 2 cannot be carried out smoothly.

Furthermore, since the housing 3 of the pickup 2 and the linear motor 5 are separate devices, the yoke 6 of the linear motor 5 is small and has a large magnetic resistance, and the thrust of the linear motor 5 is Since there are few parts that generate , only a small thrust/input ratio can be obtained.

Purpose of the invention In view of the above-mentioned problems, the present invention has been developed to reduce the size of the applicable equipment since the space occupied by the optical pick-up is small, and to make the feeding operation of the optical pick-up smooth. Moreover, it is an object of the present invention to provide a feeding device for an optical pickup that can obtain a large thrust/input ratio considering the size of the space occupied by both the optical pickup and the linear motor.

Summary of the invention The present invention provides an optical pickup whose casing is made of a magnetic material and which constitutes a part of the magnetic circuit of a linear motor; and coils constituting secondary conductors of the optical pickup, and the optical pickup is configured to be fed by the linear motor.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

2 and 3 show a feeding device for an optical pickup in an optical disk device, similar to the conventional example shown in FIG. In this optical disk device 21, a center spindle 23 is rotationally driven by a spindle motor 22, and an optical disk (not shown) is fixed to a disk table 24 located at the tip of the spindle 23. Therefore, it is rotationally driven. In other words, the rotation center of the table 24 is the rotation center of the disk (not shown).

Further, a rectangular plate-shaped yoke 26 is fixed on a rectangular plate-shaped aluminum die-cast base 25, and a rectangular plate-shaped magnet 27 is further fixed on this yoke 26. magnet 2
7 is smaller in length and width than the yoke 26. And, the yoke 26 and the magnet 27 are
The end faces 26a and 27a close to the table 24 are aligned and the center lines perpendicular to the end faces 26a and 27a are aligned so that they are overlapped with each other. Therefore, magnets 27 are provided at both end portions of the yoke 26 and at portions far from the table 24.
are not overlapped.

The magnet 27 has a yoke 26, for example, so that the magnetic flux lines pass through the magnet 27 in the thickness direction.
The surface in contact with the yoke 26 is magnetized as an S pole, and the surface opposite to the yoke 26 is magnetized as an N pole.

Above the magnet 27, this magnet 2
Two feed shafts 4 are fixed by predetermined fixing fittings 31 or the like so as to be spaced apart from the feed shaft 7 and extend perpendicularly to the end surface 27a.

The housing 32 of the optical pick-up 2 is made of a magnetic material such as iron, and is penetrated by two feed shafts 4 so that the pick-up 2 is fed in the radial direction of a disk (not shown). It is slidably supported.

The casing 32 has a shape similar to a rectangular parallelepiped with a width approximately equal to the width of the magnet 27, but the end farthest from the table 24 has a yoke 26 facing toward the part where the magnet 27 is not overlapped. A rectangular parallelepiped protrusion 32 a that once protrudes is formed over the entire width of the housing 32 . Further, a coil 33 is wound around the outer peripheral surface of the end of the housing 32 near the table 24 in a direction perpendicular to the feed shaft 4 .
As clearly shown in FIG. 3, the surface of the protrusion 32a on the yoke 26 side and the coil 33 on the magnet 27 side of the housing 32 are only slightly apart from the yoke 26 and the magnet 27, respectively.

In the embodiment described above, the magnet 27, the housing 32, the protrusion 32a, and the yoke 26 constitute a magnetic circuit, and as shown in FIG.
The magnetic flux lines 34 emanating from 7 circulate within this magnetic circuit. At this time, the magnetic flux lines 34 and the coil 33 on the magnet 27 side are perpendicular to each other, and this coil 33 constitutes a secondary conductor of the linear motor.

Therefore, when the coil 33 is energized, the magnetic flux lines 34
The coil 33 on the side of the magnet 27, which is orthogonal to The pick-up 2 can be moved to a predetermined position.

Note that even when the pick-up 2 reaches a position corresponding to the innermost circumference of the disk (not shown) by the feeding operation, the protrusion 32a does not come into contact with the end surface of the magnet 27, and the pick-up 2 does not touch the disk (not shown). The yoke 26, the magnet 27, and the housing 32 are arranged so that the coil 33 is positioned above the magnet 27 even when the coil 33 reaches a position corresponding to the outermost circumference of the coil (not shown).
The dimensions of each have been determined.

As described above, in this embodiment, the protrusion 32a is formed on the housing 32 so that the housing 32 and the yoke 26, which each constitute a part of the magnetic circuit of the linear motor, are close to each other. Therefore, the magnetic resistance of the magnetic circuit is small, and the thrust/input ratio of the linear motor that is the feeding device of the pickup 2 is large.

Application Example The present invention has been explained above based on one example.
The present invention is not limited to this embodiment, and various modifications are possible.

For example, in the above embodiment, the present invention was applied to an optical disk device, but the present invention can also be applied to various other optical devices that use an optical pickup.

Effects of the Invention As described above, in the optical pick-up feeding device according to the present invention, the casing of the optical pick-up is made of a magnetic material, and this casing constitutes a part of the magnetic circuit of the linear motor. At the same time, a coil is wound around the outer peripheral surface of the housing, and this coil constitutes a secondary conductor of the linear motor.

Therefore, the housing of the optical pickup and the linear motor serving as its feeding device are constructed as an integrated device, and the space occupied by both of them as a whole is small, making it possible to downsize the applicable equipment.

In addition, since the coil wound around the outer circumferential surface of the optical pickup's housing generates thrust as a linear motor, the center of gravity of the optical pickup and housing and the center of the thrust-generating part of the linear motor are aligned. Because they are close together, there is less mechanical resonance caused by twisting or bending in the coil part of the linear motor or the joint part between the linear motor and the housing, etc., which is required in the past, making the feeding operation of the optical pick-up smoother. can be done.

Furthermore, since the housing of the optical pickup and the linear motor that is its feeding device are constructed as an integrated device, the magnetic resistance of the magnetic circuit is small compared to the size of the space occupied by both, and the thrust is small. Since there are many generating parts, a large thrust/input ratio can be obtained.

Further, since the casing of the optical pickup is used not only as a part of the magnetic circuit but also as a coil bobbin, the cost of the feeding device of the optical pickup can be reduced.

In addition, the magnetic housing of the optical pickup is also used as a coil bobbin, but this type of housing is stronger than normal coil bobbins made of Bakelite or ceramic, and the coil can be wound tightly. As a result, the mechanical strength of the optical pickup feeding device can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a conventional example of the present invention. FIGS. 2 and 3 show an embodiment of the present invention, with FIG. 2 being a schematic perspective view and FIG. 3 being a cross-sectional view taken along the line - in FIG. In addition, in the symbols used in the drawings, 2...optical pick-up, 4...feed shaft, 26...yoke, 27...magnet, 32...casing, 32a
. . . Projection, 33 . . . Coil.

Claims (1)

[Scope of utility model registration request] an optical pickup whose housing is made of a magnetic material and which constitutes a part of the magnetic circuit of the linear motor; and an optical pickup whose housing is formed of a magnetic material and constitutes a secondary conductor of the linear motor that is wound around the outer peripheral surface of the housing. 1. A feeding device for an optical pickup, comprising a coil and a coil, respectively, and configured such that the optical pickup is fed by the linear motor.