JPH1027360A - Objective lens drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability in winding driving coils by providing a lens holder with bobbin parts. SOLUTION: Bobbin parts 13a-13d are constituted as a pair of upper and lower projecting pieces which vertically project from both outer parts of the spreads of coil 11 windings and from winding surfaces of each coil so that the bobbin parts avoid a winding part of focusing coil 11 and also limit the spread of the coil 11. Each projecting piece is formed in a shape widening out to the tip, with a brim formed on the edge to prevent the tracking coils 12a-12d from falling off, and the outermost end in the width is spread out of the range for the winding of the coil 11. Such a lens holder 2 is provided with the windings in order of the coils 11, 12a-12d sequentially by using an automatic winding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device for driving an objective lens in an optical head which emits a light beam for reading a signal from a medium such as a disk or writing a signal on the medium. About.

[0002]

2. Description of the Related Art In an objective lens driving device, a lens holder on which an objective lens is mounted is displaceably supported,
A drive coil such as a focusing coil and a tracking coil is mounted on the lens holder, and a used portion of each of the drive coils is arranged in a predetermined magnetic field formed by a magnetic circuit, so that a signal supplied to each of the drive coils is obtained. The mainstream configuration is such that the objective lens can be driven accordingly.

In such an objective lens driving device, in order to simplify the configuration and reduce the number of components, the effective driving of each driving coil is performed so that the same magnetic field acts on the signal supplied to each driving coil. It is common practice to arrange the side parts so as to overlap each other. Therefore, as shown in, for example, Japanese Patent Publication No. Hei 5-17615, each drive coil is wound around a lens holder, and then the other drive coil wound in advance is bonded and fixed from above one drive coil. A configuration in which the effective side portions of the drive coil are overlapped is arranged.

[0004]

As described above, in the case where the effective side portions of the respective drive coils are overlapped with each other by adhering and fixing the other drive coil from one of the drive coils, the lens holder has Since it is not necessary to dispose any of the drive coils on the one axis direction surface among the orthogonal three axis directions, a space for disposing the yoke constituting the magnetic circuit can be provided on that surface.

However, in such an objective lens driving device, it is necessary to use a jig to locate the bonding position of the driving coil to be bonded and fixed, and the position is shifted until the adhesive is cured. There was concern, and it was difficult to determine the position of the bonding position of the drive coil.

Further, since the adhesive penetrates between the wires constituting the drive coil due to the capillary phenomenon, there is a problem that it is difficult to adhere and fix the drive coil. Therefore, if the amount of the adhesive is excessively increased, the adhesive will The floating of the drive coil by the agent becomes a problem.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for winding a first drive coil from an outer side of a winding width of the first drive coil of a lens holder on an effective side of the first drive coil on which an effective magnetic field acts. A second bobbin portion projecting vertically from a surface of the first bobbin portion, the first drive coil being wound on the first bobbin portion, the second drive coil being overlapped from above an effective side of the first drive coil. A space in which a coil can be wound around two bobbin portions and a surface in which none of the drive coils are arranged in the orthogonal three-axis direction of the lens holder is provided in one axis direction, and a yoke constituting a magnetic circuit is arranged on the surface. And the winding of the second drive coil around the lens holder can be achieved by an automatic machine.

[0008]

1 and 2 are a plan view and a side view showing an assembled state of an objective lens driving device according to the present invention, respectively. In FIG. 1, reference numeral 1 denotes a frame formed by pressing a metal plate, and reference numeral 2 denotes a synthetic resin lens holder on which an objective lens 3 is mounted. The lens holder 2 is stretched between a wiring board 4 fixed to one end of the frame 1 by screws and a support member 5 made of synthetic resin fixed to the other end of the frame 1. It is fixed to the support wires 6 of the book, is elastically supported by the support wires 6 with respect to the frame 1, and is disposed in a rectangular space at the center of the frame 1.

Reference numerals 7 and 8 denote a pair of permanent magnets, each of which is bonded to the inner wall of a wall constituting a rectangular space in the central portion of the frame 1 so that one magnetic pole surface (N pole) of the same magnetic pole faces each other. Reference numerals 10 and 10 denote yokes having a bent structure in which the projected shape from the side is an inverted U-shape. One surface of the one yoke 9 at the boundary is a magnetic pole surface (S
Pole), and the other side surface is divided into two forks with the bent portion of one yoke 9 as a boundary, and each of the two forked portions is a magnetic pole on the opposite side to the bonding surface side with the wall surface of the frame 1. Surface (N pole)
Are arranged facing each other with a gap. On the other hand, one surface of the other yoke 10 is a magnetic pole surface (S
Pole), and the other side surface is divided into two forks with the bent portion of the other yoke 10 as a boundary, and each of the two forked portions is a magnetic pole on the opposite side to the bonding surface side with the wall surface of the frame 1. Surface (N
Pole) with a gap.

A focusing coil 11 has a winding center axis coinciding with the direction of the optical axis of the objective lens 3 and is wound around the side of the lens holder 2. It is wound in a substantially rectangular shape having a winding center axis orthogonal to the above, and is disposed at four corners of the lens holder 1 so as to form a pair of two and face the permanent magnet 7 or 8, respectively. Tracking coil.

The two parallel sides of the focusing coil 11 are arranged in a magnetic gap formed by the permanent magnet 7 and the yoke 9 or in a magnetic gap formed by the permanent magnet 8 and the yoke 10. .

Also, the tracking coils 12a to 12a
d is also disposed in the magnetic gap formed by the permanent magnet 7 and the yoke 9 or in the magnetic gap formed by the permanent magnet 8 and the yoke 10.
Due to the relationship between the arrangement positions of a to 12d and the range of their magnetic air gaps, one side of each of the tracking coils 12a to 12d near the center in the width direction of the rectangular lens holder 2 is arranged in an effective magnetic field formed by a magnetic circuit. It is supposed to be.

Next, parts related to the lens holder 2 having the features of the present invention will be described in detail with reference to FIGS. 3, 4, and 5, which show plan, front, and side views of the lens holder 2, respectively. .

The lens holder 2 includes the permanent magnets 7 and 8
Are formed on the surfaces opposed to each other, leaving a recessed shape excluding four corners and a central portion. The side of the lens holder 2 which is orthogonal to the mounting surface of the objective lens 3 is formed with a first bobbin for winding the focusing coil 11 at the center thereof. Guide portions for regulating the width are formed at four corners. The four corners of the surface of the lens holder 2 facing the respective permanent magnets 7 and 8 include:
Second bobbin portions 13a to 13d around which the tracking coils 12a to 12d are wound are formed.

The second bobbin portions 13a to 13d are provided on both outer sides of the winding width of the focusing coil 11 so as to avoid the portion where the focusing coil 11 is wound and to regulate the winding width of the focusing coil 11. The upper and lower projecting pieces projecting vertically from the winding surface of the focusing coil 11 from the respective parts are formed as a pair, and are formed in a two-shape from the front. Each of the protruding pieces is formed to have a shape that becomes wider toward the front end, and a rim for preventing the tracking coils 12a to 12d from falling off is formed at the forefront, and is formed in the width direction. Is projected outside the range where the focusing coil 11 is wound.

The lens holder 2 constructed as described above
Are the focusing coil 11 and the tracking coil 1
Winding is performed using an automatic machine in the order of 2a to 12d.

The focusing coil 11 is wound around the entire circumference of the lens holder 2, but is supported only at the four corners and the center of the surface of the lens holder 2 facing the respective permanent magnets 7, 8. The portion where the focusing coil 11 is wound is one step lower so as to regulate the winding width of the focusing coil 11 in these supporting portions.

The tracking coils 12a to 12a
The second bobbin portions 13a to 13d around which d is wound
Is formed at a position protruding from the winding surface of the focusing coil 11, so that the tracking coils 12 a to 12 d can be wound later so as to overlap the focusing coil 11 from above with the focusing coil 11 wound. I can do it. These tracking coils 1
When winding the lens holders 2a to 12d using an automatic machine, the space 14a formed by the concave shape in the surface of the lens holder 2 facing each of the permanent magnets 7 and 8 is used to install the lens holder 2 in the automatic machine. To 14d are available.

Thus, the focusing coil 1
1. The lens holder 2 in a state where the respective drive coils of the tracking coils 12a to 12d are wound is shown in a plan view of FIG. 6 and a front view of FIG. In this state, on the surface of the lens holder 2 facing each of the permanent magnets 7 and 8, the wound focusing coil 11
The space 14a on both sides of the central part
To 14d are formed. And these spaces 1
Each of the forked portions of the yokes 9 and 10 is inserted and arranged in each of 4a to 14d. Therefore, each of the forked portions of the yokes 9 and 10 can be arranged close to the focusing coil 11, and the gap between the magnetic gap and the permanent magnet 7 or 8 can be reduced, and the magnetic field strength in the magnetic gap can be reduced. This is advantageous for raising

On the other hand, in addition to the focusing coil 11, the tracking coils 12a
To 12d are also arranged. In this case, the permanent magnets 7 and 8
Is smaller than the width of the lens holder 2 and the yoke 9
1 and 10 that are orthogonal to the focusing coil 11 on the center side of the lens holder 2 of each of the tracking coils 12a to 12d from the relationship with the position where each of the two forked portions of
The magnetic flux is concentrated on the sides, each one side becomes an effective side, and the lens holder 2 is driven according to a signal flowing through the effective side.

Each of the protruding pieces constituting the second bobbin portions 13a to 13d is formed to have a shape which becomes wider toward the tip.
2d is wound from the narrow side of the second bobbin portions 13a to 13d so that the wires constituting the tracking coils 12a to 12d are wound in close contact with each other.
By providing the difference in the width of the projecting pieces, the range of the wire to be wound is expanded, and the effective amount of each of the tracking coils 12a to 12d arranged in the effective magnetic flux by suppressing the projecting amount of the projecting pieces is reduced. A sufficient amount of winding of the wire at the side can be secured.

[0022]

As described above, according to the present invention, the winding of the first drive coil is started from both outer portions of the winding width of the first drive coil of the lens holder on the effective side of the first drive coil on which the effective magnetic field acts. Since the second bobbin portion projecting from the turning surface in the vertical direction is provided, the first drive coil is wound around the first bobbin portion by using an automatic machine from above the effective side of the first drive coil. The second drive coil can be wound around the second bobbin portion so as to overlap, and the workability can be improved.

Further, the present invention has an advantage that the second bobbin portion can be used for regulating the winding width of the first drive coil. Further, since a space where a part of the magnetic circuit is arranged is provided on the side of the lens holder where the second bobbin portion is provided, the space can be used for installing the lens holder in the automatic machine. The operation of winding the second drive coil around the bobbin can be improved.

[Brief description of the drawings]

FIG. 1 is a plan view showing a completed assembly state of an objective lens driving device according to the present invention.

FIG. 2 is a side view of the objective lens driving device in FIG.

FIG. 3 is a plan view of a lens holder 2 which is a feature of the present invention.

FIG. 4 is a front view of a lens holder 2 part.

FIG. 5 is a side view of a lens holder 2 part.

FIG. 6 is a plan view showing a state where each drive coil is wound around the lens holder 2.

FIG. 7 is a front view showing a state in which each drive coil is wound around the lens holder 2.

[Explanation of symbols]

1 frame 2 lens holder 7, 8 permanent magnet 9, 10 yoke 11 focusing coil 12a, 12b, 12c, 12d tracking coil 13a, 13b, 13c, 13d second bobbin portion 14a, 14b, 14c, 14d space

Claims (3)

[Claims] 1. An objective lens driving device for driving a lens holder on which an objective lens is mounted in two orthogonal directions using the same magnetic field formed by a magnetic circuit, wherein a first driving coil is mounted on the lens holder. A first bobbin portion for winding is provided, and from the winding surface of the first drive coil from both outer portions of the winding width of the first drive coil of the lens holder on the effective side of the first drive coil on which the effective magnetic field acts. A second bobbin portion projecting in a vertical direction is provided, and the second drive coil is wound around the effective side of the first drive coil in a state where the first drive coil is wound around the first bobbin portion.
The first drive coil and the second drive coil are wound around the bobbin.
An objective lens driving device, wherein predetermined portions of the drive coils which are orthogonal to each other are arranged in the same magnetic field. 2. The objective lens driving device according to claim 1, wherein the winding width of the first driving coil is regulated by the second bobbin portion. 3. The objective lens driving device according to claim 1, wherein a space in which a part of a magnetic circuit is disposed is provided on a side of the lens holder where the second bobbin portion is provided.