JP3137255B2 - Optical pickup device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for an optical disc player, and more particularly to an optical pickup device suitable for moving an objective lens in a focusing direction and a tracking direction.

[0002]

2. Description of the Related Art Conventionally, an optical pickup for reading information recorded on a recording medium, for example, an optical pickup device of an optical video disk player, accurately emits light from a laser beam generating means to a reproduction position of an optical disk through an objective lens. Then, recording or reproduction was performed optically. In order to accurately focus the irradiation light on the recording track of the optical disk, the objective lens of the optical pickup needs to be controlled to move and drive correctly in the focusing direction and the tracking direction. FIG. 5 shows a perspective view of a conventional optical pickup device for such a purpose.

[0005] In FIG. 5, protrusions 20, 2 on both sides of a yoke 23 having three upwardly extending protrusions 20, 21, 22 (a protrusion 21 disposed at the center is not shown).
Magnets 24 and 25 are fixed to the inside of each of 2, and form a magnetic circuit together with the yoke 23. A bobbin 26 is loosely fitted to an outer peripheral portion of the center projecting portion 21 of the yoke 23, and a cylindrical support 27 is provided on an upper portion of the bobbin 26.
The objective lens 28 is fixed to the upper end of the support 27. A focus coil 29 is wound around the bobbin 26 along the optical axis of the objective lens 28. Further, the focus coil 29
A tracking coil 30, 31 having a substantially rectangular shape is fixed to the outer peripheral portion so as to be symmetrical with respect to the optical axis of the objective lens 28, and the tracking coils 30, 31 are positioned so as to face the magnets 24, 25. I have. The bobbin 26 is supported by the yoke 23 by a pair of leaf springs 32 on the upper side and a pair of leaf springs 33 on the lower side so as to be movable in the focus direction and the tracking direction.

[0004] The optical pickup device constructed as described above is provided with a detecting means (see FIG. 1) when the distance between the optical disk and the objective lens 28 changes for some reason when the optical disk (not shown) is rotated and the laser beam is out of focus. When a predetermined current is supplied to the focus coil 29 based on a detection signal detected by the focus coil 29 (not shown), the focus coil 29 is disposed so as to intersect with the magnetic circuit. The bobbin 26 moves in the vertical direction by receiving a force in the focus direction, that is, in the vertical direction, that is, the vertical direction, and the laser beam from the objective lens 28 focuses on the optical disk.

When the laser beam is irradiated in the radial direction of the optical disk, a tracking error signal (not shown) is detected, and a current is supplied to the tracking coils 30 and 31 based on the detection signal. Since one side of the tracking coils 30 and 31 is in the magnetic circuit, the objective lens 28 of the bobbin 26 moves in the direction orthogonal to the optical axis, that is, in the tracking direction, according to Fleming's left-hand rule, so that the laser light is emitted. Irradiate to the correct position on the track of the optical disc. By driving the objective lens 28 to move in the focus direction and the tracking direction in this manner, the objective lens 28 can focus the irradiation light following the rotation of the optical disk, and the signal recorded on the optical disk can be focused. Was correctly read and played.

[0006]

However, in the above-mentioned conventional optical pickup device, tracking coils 30 and 31 are adhered to the side surface of the focus coil 29 to share a single magnetic circuit. There is a drawback that it is difficult to take out the assembly position and assemble, and there is a possibility that adverse effects due to magnetic leakage may occur. Further, in general, when the coils are in the same magnetic gap, there is a problem that the directions of currents supplied to the coils are opposite to each other at positions opposite to each other, so that the forces cancel each other and the efficiency of the magnetic circuit is reduced. In order to avoid this, the conventional example has a structure in which only one side of the tracking coils 30 and 31 is disposed in the magnetic gap, and there is a drawback that it is difficult to mount the coils.

Further, since a coil having a relatively large shape is wound and adhered to the bobbin 26 to which the objective lens 28 of the movable portion is mounted, the coil cannot be made compact and the efficiency of the movable portion decreases. As a result, there is a problem that power consumption increases. The present invention has been made in view of the above points, and aims to eliminate the drawbacks of the conventional example, to eliminate the effects of magnetic leakage by providing a magnetic circuit for each of the focus direction and the tracking direction, Another object of the present invention is to provide an optical pickup device which realizes a compact configuration and has a good balance of the center of gravity of the movable portion.

[0008]

An optical pickup device according to the present invention is an optical pickup device for reading information recorded on a recording medium. The optical pickup device includes a bobbin equipped with an objective lens and a focus attached to a front position of the bobbin. A coil, a tracking coil attached to a rear side position of the bobbin, and one end of the base member at substantially the same position as a front-rear position of the objective lens on the bobbin, wherein the focus coil and the tracking coil of the bobbin The other end is mounted in between, and two substantially linear upper and lower, left and right suspension springs for cantileverly mounting the bobbin, and a tracking spring disposed on the base member side facing the focus coil. A yoke plate, a focus magnet attached to the focus yoke plate,
A tracking magnet attached to the tracking yoke plate is provided, and a first magnetic circuit formed by the focus coil, the focus yoke plate, and the focus magnet is formed by the tracking coil, the tracking yoke plate, and the tracking magnet. The second magnetic circuit does not intersect. Further, in the optical pickup device of the present invention, a small mounting hole is formed at both ends of the suspension spring, and a mounting projection is provided at a spring mounting position of the bobbin and the base member. The suspension spring is mounted by fitting small holes at both ends of the bobbin into respective projections of the bobbin and the base member.

[0009]

According to the present invention, by supplying a current to the above-mentioned focus coil, the first magnetic circuit in the focus direction operates to move the objective lens against the suspension spring 6 in the focus direction, that is, in the light direction. The second magnetic circuit in the tracking direction works against the suspension spring 6 by supplying a current to the tracking coil, and the objective lens is moved in the direction parallel to the axis. It can be driven to move in a direction perpendicular to the axis. The first magnetic circuit for focusing and the second magnetic circuit for tracking do not interfere with each other.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical pickup device according to the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of the optical pickup device with a cover removed.
FIG. 2 is an exploded perspective view showing each member disassembled, FIG. 3 is a perspective view showing a state where a flexible printed circuit board is attached to a base member, and FIG. 4 is a state before attachment to a base of an optical pickup device. It is the front view which showed. In the drawing, 1 is an objective lens, 2 is a bobbin, the objective lens 1 is fixed to the upper end of the bobbin 2, 3 is a focus coil, and the focus coil 3 is wound into two substantially rectangular shapes. And attached to a predetermined position of the bobbin 2. 4 is a tracking coil,
The tracking coil 4 is a coil that is divided into two and wound, has a substantially central portion formed in a hollow shape, and this hollow portion is fitted into the convex portion 2 a of the bobbin 2 and adhered.

Reference numeral 5 denotes a base member, and reference numeral 6 denotes a suspension spring. The suspension spring 6 is an elastic member having a locking portion having locking holes 6a at both ends of a long shape. The locking holes 6a are fitted into and fixed to convex portions 5a provided at predetermined positions in the vertical and horizontal directions of the base member 5. Thereby, each suspension spring 6 is attached to the base member 5. Suspension spring 6
The other side locking holes 6a are fitted into and firmly fixed to the projections 2b of the bobbin 2, respectively, and the bobbin 2 is suspended by the suspension spring 6 in a cantilever state. Reference numeral 7 denotes a flexible printed circuit board, and the flexible printed circuit board 7 can arbitrarily bend to a predetermined mounting form as shown in the figure.

Reference numeral 8 denotes a base plate of the optical pickup, and 9 denotes a focus yoke plate attached to the base plate 8. The focus yoke plate 9 is formed in a substantially U-shape and has two Is attached. Reference numeral 11 denotes a tracking yoke plate, and a tracking magnet 12 is attached to the tracking yoke plate 11. Reference numeral 13 denotes a base on which the base plate 8 is mounted. The base 13 is mounted on a chassis (not shown) of a carriage mechanism of the optical pickup device. Reference numeral 14 denotes a cover of the optical pickup.

The base member 5 is screwed to a base plate 8, and a substantially U-shaped focusing yoke plate 9 and a tracking yoke plate 11 are provided on the base plate 8 for the objective lens 1.
Are screwed and fixed at predetermined positions before and after the mounting position. The focus yoke plate 9 and the tracking yoke plate 11 are provided with the focus magnet 1 as described above.
0, a tracking magnet 12 is attached to a predetermined position, respectively,
Projections 9a and 11a are formed at positions facing the tracking magnet 12, respectively, and the substantially rectangular focus coil 3 is loosely fitted to the projection 9a to form a magnetic gap. The tracking coil 4 is disposed between the tracking coil 4 and the portion 11a to form a magnetic gap.

That is, a focus coil 3 and a focus magnet 10 are disposed on the left and right sides of the objective lens 1 held substantially at the center of the bobbin 2 to form a first magnetic circuit in the focus direction. The two magnetic circuits are formed by arranging two coupled tracking coils 4 and tracking magnets 12 at substantially the center between the four suspension springs 6. By supplying current to the focus coil 3 of the magnetic circuit formed in this way, the focus direction in the direction of arrow A according to the Fleming's left hand rule, that is,
The bobbin 2 can be moved in the vertical direction parallel to the optical axis, and the current flows through the tracking coil 4 so that the bobbin 2 is moved in the tracking direction in the direction of arrow B, that is, in the left-right direction orthogonal to the optical axis. The objective lens 1 can be moved.

A current is supplied to the focus coil 3 and the tracking coil 4 by a flexible printed circuit board 7.
Is supplied via A supply current from various external signal sources is applied to the connector 7a of the flexible printed circuit board 7, and the flexible printed circuit board 7 is wired to a relay terminal 7b provided on the base member 5 as shown in FIG. From 7b, a supply current is applied to each coil via a wiring member (not shown). The flexible printed circuit board 7 has a component mounting portion 7d, and a printed circuit board 7c provided at one end by being bent in a predetermined direction as shown in the figure is wired to the end 13a of the base 13. . A laser light source (not shown) is attached to an end portion 13 a of the base 13, and a supply current of the laser light source is supplied through the flexible printed circuit board 7.

The light beam emitted from the laser light source is
Is incident on the objective lens 1 via a lens system and an internal mirror provided therein, and this light beam is converged by the objective lens 1 and focused on the optical disk. The movement of the objective lens 1 in the direction parallel to the optical axis (focus direction) and the direction perpendicular to the optical axis (tracking direction) together with the bobbin 2 as described above, accurately traces the recording tracks on the optical disc to reproduce the recorded information. be able to.

[0017]

As described above, in the optical pickup device according to the present invention, since the focus control magnetic circuit and the tracking control magnetic circuit are provided before and after the objective lens 1, magnetic leakage from each magnetic circuit is achieved. In addition, it is possible to prevent the adverse effect of the objective lens 1 and to eliminate the bias of the center of gravity of the bobbin 2 of the movable portion of the objective lens 1 including the focus coil 3 and the tracking coil 4, and to smoothly move the focus direction and the tracking direction. There is an effect that can be. Further, the dimensional length of the suspension spring 6 supporting the bobbin 2 can be arbitrarily determined.
There is also an effect that the movable spring constant can be easily set. Moreover, the structure is simple and the objective lens 1
There is an advantage that the structure of the bobbin 2 of the movable portion can be made compact, and the bobbin 2 can be configured at a low cost and is easy to implement.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state where a cover is removed in an embodiment of an optical pickup device according to the present invention.

FIG. 2 is an exploded perspective view of the optical pickup device of FIG.

FIG. 3 is a perspective view showing a state where a flexible printed circuit board is attached to the base member of FIG. 1;

FIG. 4 is a plan view showing a state before attachment to the base of FIG. 1;

FIG. 5 is a perspective view showing a conventional example of an optical pickup device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens 2 Bobbin 3 Focus coil 4 Tracking coil 5 Base member 6 Suspension spring 7 Flexible printed circuit board 8 Base plate 9 Focusing yoke plate 10 Focus magnet 11 Tracking yoke plate 12 Tracking magnet 13 Base 14 Cover

Claims (2)

(57) [Claims] 1. An optical pickup device for reading information recorded on a recording medium, comprising: a bobbin having an objective lens mounted thereon; and a focuser mounted at a front position of the bobbin.
Coil and a track attached to the rear side of the bobbin.
One end of the king coil and the base member and the bobbin
Position approximately the same as the front and rear position of the objective lens
The focus coil and the track in the bobbin
The other end is attached between the coil and the bobbin.
Two suspension springs, which are arranged on the base member side, facing the focus coil, and attached to the focusing yoke plate. Focus magnet and
A tracking magnet attached to the tracking yoke plate is provided, and a first magnetic circuit formed by the focus coil, the focus yoke plate, and the focus magnet is formed by the tracking coil, the tracking yoke plate, and the tracking magnet. An optical pickup device wherein the second magnetic circuit does not intersect. 2. A small mounting attachment at both ends of the suspension spring.
A hole is formed, and the bobbin and the base member are spring-mounted.
A mounting projection is provided at a position,
Small holes at both ends of the bobbin and each projection of the base member
By fitting the suspension spring,
Optical pickup device according to claim 1, characterized in that the.