JPH11134679A - Objective lens driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens driving device in which the objective lens is hardly tilted to an optical disk even when the objective lens is operated in the focusing direction. SOLUTION: A positional relation in the radial direction of an optical disk between the supporting center of a movable part, in which an objective lens 1 connected to a supporting holder 9 through an elastic supporting member 11 is arranged, and a magnetic circuit composed of a magnet 5 and a yoke 4 is made to be an adjustable structure. Consequently, even when the accuracy of a single part of the respective parts and its assembling accuracy are somewhat low, adverse effect caused by them is absorbed and the objective lens driving device, being hardly tilted the radial direction of the optical disk even when the objective lens 1 is operated in the focusing direction, is realized.

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 used for an optical disk device.

[0002]

2. Description of the Related Art An example of an objective lens driving device used in an optical disk device is disclosed in, for example, JP-A-8-26386.
No. 0 is known.

FIG. 7 shows the configuration of the objective lens driving device.

[0004] It comprises a bobbin 2 holding an objective lens 1, a focus coil 3, a tracking coil 6, and a magnetic circuit section comprising a magnet 5 and a yoke 4.
Driving means for driving and displacing the objective lens 1 in a focusing direction (the optical axis direction of the objective lens) and a tracking direction (a direction perpendicular to the optical axis of the objective lens); and a plurality of elastic support members 11 for supporting the bobbin 2; A support holder 9 constituting a fixed portion and a fixed portion substrate 10 attached to the support holder 9 and having one end of an elastic support member 11 fixed thereto.
And At the time of focus control, an electromagnetic force acts in the focusing direction by flowing a current in the forward or reverse direction to the focus coil 3, and moves the objective lens 1 in the optical axis direction in response to the surface deflection of the recording surface of the optical disc.
The light beam spot can follow the recording surface of the optical disk. At the time of the tracking control, an electromagnetic force acts in the radial direction of the optical disk by applying a current to each tracking coil 6 in the forward or reverse direction, so that the light beam spot can follow the eccentricity and meandering of the track of the optical disk. .

[0005]

In recent years, there has been a tendency to use an objective lens having a large numerical aperture in order to increase the recording density of an optical disk device. Therefore, strict accuracy is required for the relative angle shift amount between the objective lens and the optical disk. In particular, the tilt angle of the objective lens changes with respect to the initial tilt angle of the objective lens even while the objective lens is moving up, down, left, and right, following the surface deviation of the optical disk and the meandering and eccentricity of the track on the optical disk. It is required to suppress the inclination of the objective lens so as not to prevent the inclination.

FIG. 9 shows a conventional example shown in FIG.
The relationship between the magnet 5 and the focus coil 3 is shown from the direction. As shown in FIG. 9, when the assembling accuracy and the component accuracy of each component are in an ideal state, it is generated by the action of the current flowing through the focus coil 3 and the magnetic flux in the magnetic circuit composed of the magnet 5 and the yoke 4. The relative position between the center P of the driving force in the focusing direction and the support center (or the center of gravity) G mainly determined by the mounting accuracy or the component accuracy of the elastic support member 11 substantially coincides. In this state, the object is moved in the focusing direction. When the lens is operated, the objective lens hardly tilts.

On the other hand, FIG. 8 shows that in the conventional example shown in FIG. 7, the center P of the driving force in the focusing direction coincides with the support center (or center of gravity) G of the movable part due to the assembling accuracy and the accuracy of the components. It shows the case where it is not done.
FIG. 10 shows the relationship between the magnet 5 and the focus coil 3 when viewed from the direction of the arrow E in FIG. As shown in FIGS. 8 and 10, the center P of the driving force in the focusing direction and the support center (or center of gravity) G
Do not coincide with each other, the focusing direction driving force is generated at a substantially central portion of the magnet 5, and the center P of the focusing direction driving force is generated at a position shifted by y from the support center (or the center of gravity) G of the movable portion. In this state,
When the objective lens is operated in the focusing direction, the center P of the driving force in the focusing direction simultaneously generates a rotational torque (P × y) for tilting the objective lens 1 in the radial direction of the optical disk. Therefore, the objective lens 1 is inclined in the radial direction of the optical disc.

In particular, in the case of a small and thin objective lens driving device, the spring constant of the elastic supporting member is small and the interval between the elastic supporting members cannot be made large, so that the inclination of the objective lens 1 with respect to the rotational torque generated by the focusing operation. The angular sensitivity becomes large, and the inclination angle of the objective lens 1 cannot be suppressed to a small value unless the accuracy of assembling the movable part, the elastic support member, the magnetic circuit and the like and the accuracy of individual parts are remarkably improved.

As described above, in the above-described configuration of the conventional objective lens driving device, if the inclination angle during the operation of the objective lens 1 is to be suppressed to a small value, it is necessary to dramatically improve the component accuracy and the assembly accuracy. Thin lens drive,
There is a problem that requirements for miniaturization and cost reduction cannot be satisfied at the same time.

The present invention has been made to solve the above problems, and has as its object to realize an objective lens driving device in which the tilt angle of the objective lens 1 hardly changes even when the objective lens 1 operates in the focusing direction.

[0011]

SUMMARY OF THE INVENTION The above-mentioned conventional apparatus has the following problems.
It is solved by the following method. That is, an objective lens for condensing a light beam on an optical disk, and at least one lens for generating a force for driving the objective lens in the optical axis direction.
At least one focus coil, at least one tracking coil for generating a force for driving the objective lens in the radial direction of the optical disk, and a bobbin holding at least the objective lens, the focus coil, and the tracking coil A movable part composed of
At least one elastic support member having one end fixed to the movable portion and elastically supporting the movable portion, a support holder to which the other end of the elastic support member is fixed, and acting on the focus coil and the tracking coil. In an objective lens driving device provided with at least one magnetic circuit for generating a magnetic flux, a structure in which the support holder elastically supporting the movable portion can move independently of the magnetic circuit in a radial direction of the optical disc. And

Further, at least one protrusion is arranged on the mounting surface of the support holder, and a part of the yoke member of the magnetic circuit, or the support holder and the yoke, in which the mounting surface of the support holder is in close contact. At least one or more rectangular, oval, or circular fitting holes are provided on a part of the connecting member for fitting with the projections arranged on the support holder.

A yoke constituting the magnetic circuit;
Alternatively, at least one projection is disposed on a surface of the connecting member between the yoke and the support holder where the mounting surface of the support holder is in close contact, and the protrusion is disposed on the yoke on the mounting surface of the support holder. At least one or more rectangular, oval, or circular fitting holes are arranged so as to fit with the projections.

Further, a screw hole is provided in a part of the yoke constituting the magnetic circuit or in a part of the part other than the support holder so that a screw capable of pushing the support holder in a radial direction of the optical disk can be arranged. Deploy.

Further, a screw and / or a spring are arranged so that the mounting surface of the support holder is brought into close contact with the yoke constituting the magnetic circuit or the connecting member between the support holder and the yoke.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment of the objective lens driving device according to the present invention will be described.

FIG. 1 is an explanatory diagram showing the structure of a first embodiment according to the present invention.

In FIG. 1, an objective lens 1, a focus coil 3, a tracking coil 6, and a relay board 12 are arranged on a bobbin 2 to form a movable portion. A magnetic circuit composed of a pair of magnets 5 and yoke 4
Part of focus coil 3 and tracking coil 6
Are located in the magnetic gap. The driving force in the focusing direction is mainly a component extending in the tracking direction of the focus coil 3 located in the magnetic gap (a component extending in the radial direction of the optical disk).
3a.

The movable section is elastically supported by four elastic support members 11. That is, one end of the elastic support member 11 is physically and electrically connected to the relay board 12 disposed on the movable portion by solder or the like, and the other end is provided on the support holder 9 disposed on the fixed portion. It is physically and electrically coupled to the fixed part substrate 10. The four elastic support members 11 are made of a conductive material, and are electrically coupled to the focus coil 3 and the tracking coil 6 via a relay board 12 disposed on the movable portion. ing. Therefore, the fixed part substrate 10
Through the elastic supporting member 11, the focus coil 3 and the tracking coil 6 can be energized.

FIG. 2 is a sectional view showing a section taken along line BB of FIG. 1, and FIG. 3 is a sectional view showing a section taken along line AA of FIG. As shown in FIGS. 2 and 3, two bosses 9 a and 9 b are disposed on the mounting surface of the support holder 9, and the two bosses 9 a and 9 b
Are fitted into two oblong holes 4a, 4b arranged in a part of the yoke 4 to which the mounting surface of the yoke 4 is in close contact. Further, the two oblong holes 4a and 4b arranged on the yoke 4 are long holes in the radial direction of the optical disk. Further, the support holder 9 is pressed against the yoke 4 by a screw 14 via a spring 15 so as not to be lifted from the yoke 4 as a mounting surface thereof. Therefore, the bosses 9a and 9b of the support holder 9 and the long hole 4 of the yoke 4
a, 4b, the support holder 9 to which the movable part is connected can be moved only in the radial direction of the optical disc,
The optical disk is constrained in the tangential direction and the focus direction of the optical disk, and has a structure that can hardly move.

The tilt angle of the objective lens 1 when operating in the focusing direction in the above configuration will be described.
The positional relationship between the magnet 5, the yoke 4, and the focus coil 3 when viewed from the arrow C in FIG. 1 is the same as that in FIG. When a current is passed through the focus coil 3 via the elastic support member 11 made of a conductive material, the current flowing through the focus coil 3a and the focus coil 3a generated from a magnetic circuit arranged so as to sandwich that portion are substantially the same as the focus coil 3a. The focusing coil 3a generates a driving force in the focusing direction due to the electromagnetic action with the magnetic flux flowing in the orthogonal direction. However, as described above, the support holder 9 is configured such that the bosses 9a and 9b disposed on the mounting surface thereof have the elongated holes 4a and 4b of the yoke 4.
b, it is constrained in the tangential direction of the optical disc, but is movable in the radial direction of the optical disc. In the initial state, it is connected to the support holder 9 via the elastic support member 11. The support center G of the movable portion does not always coincide with the center P of the driving force in the focusing direction which substantially coincides with the center of the magnetic circuit.

In this state, while monitoring the inclination of the objective lens 1 by a method such as an autocollimator, a current is applied to the focus coil 3 to move the movable portion in the focusing direction. While repeating this operation, the adjusting screw 13 that is arranged in a part of the yoke 4 and moves in the radial direction of the optical disk is rotated, and the entire support holder 9 is moved in the radial direction of the optical disk. Then, the position where the objective lens 1 does not incline in the radial direction of the optical disk can be always found even when the movable portion on which the objective lens 1 is disposed is operated in the focus direction. By stopping the rotation of the adjusting screw 13 at this position, the support center G of the movable portion and the center P of the driving force in the focusing direction can be almost completely matched as shown in FIG. As a result, the objective lens 1 hardly tilts in the radial direction of the optical disc due to the focusing operation even if the assembly accuracy of each component and the accuracy of the individual components are somewhat rough as shown in FIG.

In the first embodiment of the present invention, the support holder 9 is disposed on a part of the yoke 4, but the present invention is a movable holder connected to the support holder 9 via an elastic support member 11. Any structure can be used as long as the center of support G of the unit and the center P of the driving force in the focusing direction that changes depending on the positional relationship between the magnetic circuit and the focus coil 3 can be made to coincide. For example, the same effect can be obtained even if the support holder 9 is not arranged as a part of the yoke 4 but a connecting member for connecting the support holder 9 and the yoke 4 is provided and the support holder is attached to this connecting member. Can be

FIG. 5 is a structural explanatory view showing a second embodiment according to the present invention.

In FIG. 5, two bosses 9a arranged on a mounting surface of a support holder 9 on which a movable portion is elastically supported,
9b is different from the first embodiment in that the connecting member 1 connects the yoke 4 and the support holder 9 instead of the yoke 4.
It is configured to fit into the oblong hole arranged in 6. Other configurations are the same as those of the first embodiment. Therefore, similarly to the first embodiment, the support holder 9 having the movable portion elastically supported is provided only in the radial direction of the optical disc.
Since it is movable independently of the magnetic circuit, the same effects as in the first embodiment can be obtained.

FIG. 6 is a structural explanatory view showing a third embodiment according to the present invention.

In FIG. 6, the mounting surface of the support holder 9 on which the movable portion is elastically supported is
Oval holes 9a and 9b are arranged to be fitted with the bosses 4a and 4b. Therefore, as in the first embodiment, the support holder 9 having the movable portion elastically supported is movable only in the radial direction of the optical disk independently of the magnetic circuit.
The same effects as in the first embodiment can be obtained.

Although the embodiments have been described above, according to the present invention, the support holder 9 for supporting the movable portion includes the yoke 4,
It is sufficient that the position can be adjusted with respect to the magnetic circuit formed by the magnet 5, and another configuration may be used. Also,
In each of the above embodiments, the support holder 9 is movable.
Conversely, it is needless to say that the support holder 9 may be fixed and the yoke 4 and the magnet 5 may be movable to adjust the position.

By mounting the objective lens driving device described in the present embodiment on an optical disk device, the inclination of the objective lens can be suppressed, the recording density of the optical disk can be increased, and the cost of the optical disk device can be reduced. Needless to say, this can be achieved.

[0031]

As described above, according to the present invention, in the objective lens driving device, the elastic support member 11 is attached to the support holder 9.
Each component can be adjusted by adjusting the positional relationship in the optical disk radial direction between the movable portion on which the objective lens 1 elastically supported is disposed via the magnetic circuit and the magnet 5 and the yoke 4. Even if the precision of the individual parts and the precision of their assembly are somewhat rough, the adjustment mechanism absorbs those adverse effects, so that the objective lens 1 is hardly inclined with respect to the optical disc when the objective lens 1 is operated in the focusing direction. There are effects that can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a first embodiment of an objective lens driving device according to the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a state explanatory view showing a case where the mounting accuracy of the magnet is rough in the first embodiment of the objective lens driving device according to the present invention.

FIG. 5 is a configuration explanatory view showing a second embodiment of the objective lens driving device of the present invention.

FIG. 6 is a configuration explanatory view showing a third embodiment of the objective lens driving device of the present invention.

FIG. 7 is a configuration explanatory view showing an example of a conventional objective lens driving device.

8 is a schematic diagram showing a case where the mounting accuracy of the magnet is rough in the conventional objective lens driving device shown in FIG.

FIG. 9 is a schematic diagram of the magnet and the focus coil viewed from the direction of arrow D shown in FIG. 7;

FIG. 10 is a schematic view of a magnet and a focus coil viewed from the direction of arrow E shown in FIG. 8;

[Explanation of symbols]

1 Objective lens 2 Bobbin 3 Focus coil 3a Component almost parallel to the longitudinal direction of the elastic support member of the focus coil 4 First yoke 5 First magnet , 6 tracking coil, 7 second yoke, 8 second magnet, 9 support holder, 10 fixed substrate, 11 elastic support member, 12
…… Relay board, 13… Adjustment screw, 14 …… Screw, 15
... spring, 16 ... connecting member.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinya Fujimori 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia Systems Development Division of Hitachi, Ltd. (72) Inventor Nobuyuki Maeda Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292 Hitachi, Ltd. Multimedia Systems Development Division (72) Inventor Seiichi Kato 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.

Claims (6)

[Claims] An objective lens for condensing a light beam on an optical disk, at least one or more focus coils for generating a force for driving the objective lens in the optical axis direction, A movable portion including at least one or more tracking coils for generating a force for driving in a radial direction, a bobbin holding at least the objective lens, the focus coil, and the tracking coil, and At least one elastic support member having one end fixed and elastically supporting the movable portion, a support holder to which the other end of the elastic support member is fixed, and a magnetic flux acting on the focus coil and the tracking coil are generated. An objective lens driving device having at least one or more magnetic circuits, wherein: Position of the support holder, the objective lens driving device, characterized in that it comprises a movable structure in the disk radial direction. 2. The yoke member of the magnetic circuit, wherein at least one protrusion is arranged on a mounting surface of the support holder, and a rectangular, oval, or circular fitting hole to be fitted with the protrusion is attached to the support holder. 2. The objective lens driving device according to claim 1, wherein the objective lens driving device is provided on a part or a part of a connecting member between the support holder and the magnetic circuit. 3. A yoke constituting the magnetic circuit, or
At least one projection is disposed on a surface of the connecting member between the yoke and the support holder where the mounting surface of the support holder is in close contact, and a rectangular, oval, or circular fitting hole to be fitted with the projection is provided in the support holder. At least one on the mounting surface
2. The objective lens driving device according to claim 1, wherein at least two of the objective lens driving devices are arranged. 4. An objective lens driving device according to claim 1, further comprising an adjusting means for adjusting a position of said support holder in a radial direction of said optical disk with respect to said magnetic circuit. 5. A screw hole for allowing a screw capable of pushing the support holder in a radial direction of the optical disc to be disposed in a part of a yoke constituting the magnetic circuit or a part of a part other than the support holder. 5. The objective lens driving device according to claim 4, wherein the objective lens driving device is disposed. 6. A screw and / or a spring are arranged so that a mounting surface of the support holder is in close contact with a yoke constituting the magnetic circuit or a connecting member between the support holder and the yoke. The objective lens driving device according to claim 4, wherein: