JPH06162534A - Device for driving objective lens - Google Patents

Abstract

PURPOSE:To improve the rigidity of a lens holder and to improve characteristics in the point of higher order resonance by attaching the bobbin to the lens holder while stretching the bobbin to bisect the space of the lens holder. CONSTITUTION:While an objective lens 2 is stuck to the lens holder 1, a focusing coil 4 and each tracking coil 5 are provided on the bobbin 6, is then stuck to the lens holder 1. In this case, in the completed state of the driving device for the objective lens, since the bobbin 6 is attached to the lens holder while being stretched to bisect the space of the lens holder, the rigidity of the lens holder 1 is improved and the characteristics are enhanced in the point of higher order resonance.

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 pickup device for reading a signal from a medium using a light beam or writing a signal in the medium.

[0002]

2. Description of the Related Art As is well known, an objective lens driving device provided in an optical pickup device for reading a signal from a medium such as a disk using a light beam or writing a signal in the medium is a magnetic field generated by a magnetic circuit. And a lens holder to which a drive coil is attached in the magnetic field is arranged to movably support the frame, and the relationship between the direction of the current flowing through the drive coil and the direction of the magnetic flux passing through the drive coil. The driving coil and the magnetic circuit are set so that the lens holder, that is, the objective lens, can be driven in a predetermined direction.

As such an objective lens driving device,
As disclosed in Japanese Patent Laid-Open No. 3-91122, the objective lens is arranged so as to be offset from the lens holder, a space for arranging the drive coil and the magnetic circuit is secured in the central portion of the lens holder, and the optical path of the light beam is set. It is known that a portion for arranging a reflecting mirror for bending and an optical path of the light beam thereof are configured to be secured and the thickness is reduced.

[0004]

The objective lens driving device of the above-mentioned publication has an air-core structure in which a driving coil is solidified in order to secure a space for arranging a magnetic circuit. Therefore, the objective lens driving device is driven in two axial directions. The two types of drive coils (focusing coil and tracking coil) must be manually adhered to the lens, and the drive coil integrated and adhered must be positioned using a jig and adhered to the lens holder. There was a problem with sex.

[0005]

The present invention has been made in view of the above-mentioned problems, and is arranged in a magnetic field formed by a magnetic circuit, and drives an objective lens by interaction with the magnetic field. The drive coil through which the control signal is sent is wound around a bobbin which is separate from the lens holder, and the bobbin is attached to the lens holder so as to extend so as to divide the space of the lens holder into two.

[0006]

According to the present invention, the bobbin for winding the drive coil is provided separately from the lens holder so that the bobbin can be wound around the bobbin by using an automatic machine. By attaching the drive coil, the drive coil is arranged at a predetermined position of the lens holder.

[0007]

1 is a plan view showing a completed state of an objective lens driving device according to the present invention. In the figure, reference numeral 1 denotes a lens holder in which an objective lens 2 is mounted at a deviated position, and in the lens holder 1, a space 3 is formed in a central portion as shown in a developed plan view of FIG. At the same time, a focusing coil 4 having a winding center axis aligned with the optical axis direction of the objective lens 2, and a tracking coil 5 having a winding center axis orthogonal to the optical axis direction of the objective lens 2.
A bobbin 6 around which is wound is attached so as to span the space 3 in two.

Reference numeral 7 is arranged in the space 3 of the lens holder 1 and includes a focusing coil 4 and a tracking coil 5.
Is a magnetic circuit that generates a magnetic flux penetrating a predetermined portion of the. The magnetic circuit 7 has a pair of permanent magnets 8 and 9 of which one magnetic pole surfaces of the same polarity are opposed to each other, and the focusing coil 4 is interposed on one magnetic pole surface of each of the permanent magnets 8 and 9. And inner yokes 10 and 11 facing each other and outer yokes 12 and 13 attached to the other magnetic pole surfaces of the permanent magnets 8 and 9, respectively.

A frame 14 is a magnetic metal plate,
For example, it is integrally formed with the inner yokes 10 and 11 and the outer yokes 12 and 13 by cutting and bending by press working using a cold rolled steel plate (SPC).

Reference numeral 15 denotes a plurality of wires (4 wires) for elastically supporting the lens holder 1 with respect to the frame 14. One end of each wire 15 is the frame 1
Printed circuit board 1 screwed to the first side surface portion 14a of No. 4
A plurality of holes (corresponding to each wire 15) are formed on a supporting member 17 made of synthetic resin, which is fixed to 6 by soldering and the other end of which is screwed to the second side surface portion 14b of the frame 14. It is stretched by being inserted into (not shown). And each of the wires 15
Are fixed by soldering to a mounting portion 18 made of a printed circuit board having an intermediate portion mounted on the lens holder 1.

Next, a method of assembling the objective lens driving device shown in FIG. 1 will be described.

First, the following preparations are made individually.

Inner yokes 10, 11 and outer yoke 1
2, 13 and the frame 14 are integrally formed, and permanent magnets 8 and 9 are attached to the outer yokes 12 and 13 and bonded.

A support member 17 is screwed to the second side surface portion 14b of the frame 14, and the printed circuit board 16 is provided.
At this time, one end of each wire 15 is soldered.

Further, the objective lens 2 is bonded to the lens holder 1. On the other hand, the focusing coil 4 and each tracking coil 5 are wound around the bobbin 6, and the bobbin 6 is bonded to the lens holder 1.

The bobbin 6 has a shape as shown in the plan view of FIG. 3A and the side view of FIG. 3B, and the focusing coil 4 and each tracking coil 5 are sequentially operated by an automatic machine. It is designed to be wrapped.
Further, the bobbin 6 has upper and lower engagement pieces 20a and 20 which are engaged with guide protrusions 19 (shown in FIG. 4) formed on an inner wall of the lens holder 1 which forms the space 3.
b is formed on the joint surface with the inner wall. As shown in the side view of the lens holder 1 in FIG. 4, the guide protrusion 19 has a wide portion 19a formed at the upper end thereof, while the upper portion of the guide protrusion 19 is formed corresponding to the wide portion 19a. A step is formed on the engaging piece 20a. Therefore, the bobbin 6 is attached to the engagement pieces 20a and 2 from below the lens holder 1.
By engaging 0b with the guide protrusion 19 and inserting it into the space 3, the upper engagement piece 20a is brought into contact with the wide portion 19a of the guide protrusion 19 at the step, and the bobbin 6 is positioned.

Each preparation is carried out in this way. And
First, the lens holder 1 to which the bobbin 6 is attached is arranged so that the magnetic circuit 7 is located in the space 3. In this case, the inner yokes 10 and 11 are arranged in the notches of the bobbin 6, respectively, and a predetermined portion of the focusing coil 4 is interposed between the inner yokes 10 and 11 and the permanent magnets 8 and 9.

After that, the unsoldered other ends of the respective wires 15 soldered to the printed circuit board 16 are inserted from the outside of the first side face portion 14a of the frame 14 and then inserted into the corresponding holes of the support members 17, respectively. To do. Then, the printed board 16 is attached to the first side surface portion 1 of the frame 14.
Each wire 15 is stretched by screwing to 4a. Here, the wires 15 are respectively connected to the lens holder 1
Is disposed adjacent to each mounting portion 18 mounted on the. Therefore, the mounting portion 1 corresponding to each of the wires 15
8 can be soldered. The lens holder 1 is fixed to the middle portion of each wire 15 by this soldering, and the lens holder 1 is displaceably supported on the frame 14 to complete the assembly.

In the completed state of the objective lens driving device,
The pair of permanent magnets 8 and 9 are arranged such that the same magnetic pole surfaces face each other across the bobbin 6, and the focusing coil 4 and each tracking coil 5 are orthogonal to each other in the portion facing the magnetic pole surface. There is. For that reason,
The focusing coil 4 and each tracking coil 5
The magnetic fluxes from the permanent magnets 8 and 9 penetrate substantially orthogonally to the lens holder 1 by supplying control currents to the focusing coil 4 and the tracking coils 5, respectively. Can be driven in any direction.

By the way, in the completed state of the objective lens driving device, since the bobbin 6 is attached to the lens holder 1 so as to span the space 3 of the lens holder 1, the rigidity of the lens holder 1 is improved. Can be measured.

Further, as described above, since the bobbin 6 is formed separately from the lens holder 1, the bobbin 6 has a high degree of freedom in its shape, and the focusing coil 4 and each tracking coil 5 can be easily wound by an automatic machine. The bobbin 6 can be easily achieved, the guide protrusion 19 is formed on the lens holder 1, and the bobbin 6 is engaged with the engaging piece 2
0a and 20b are formed so that the bobbin 6 is positioned, and workability when the bobbin 6 is attached to the lens holder 1 is taken into consideration.

[0022]

As described above, in the objective lens driving device according to the present invention, the driving coil is wound around the bobbin which is separate from the lens holder, and then the hobbin is attached to the lens holder. The drive coil can be wound by an automatic machine, which has the advantage of improving workability. Further, according to the present invention, since the bobbin is attached to the lens holder by spanning the space of the lens holder so as to divide the space of the lens holder into two, the rigidity of the lens holder can be improved and a high-order resonance point can be obtained. Can improve the characteristics.

[Brief description of drawings]

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

FIG. 2 is a developed plan view showing a main part of the present invention.

3A and 3B are respectively a plan view and a side view showing the shape of a bobbin which is a main component of the present invention.

FIG. 4 is a side sectional view of a lens holder, which is a main component of the present invention.

[Explanation of symbols]

1 Lens Holder 3 Space 4 Focusing Coil 5 Tracking Coil 6 Bobbin 7 Magnetic Circuit 19 Guide Projection 20a, 20b Engagement Piece

Claims (1)

[Claims] 1. An objective lens driving device in which an objective lens is mounted at an offset position of a lens holder, and a space for arranging a magnetic circuit is formed in a central portion of the lens holder, which is formed by the magnetic circuit. A driving coil, which is arranged in a magnetic field and through which a control signal for driving an objective lens is flowed by the interaction with the magnetic field, is wound around a bobbin separate from the lens holder, and the bobbin is placed in the space of the lens holder. An objective lens driving device, characterized in that the objective lens driving device is constructed so that it is mounted on a lens holder so as to be divided into two parts.