JPH1166584A - Objective lens driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an objective lens driver which enables miniaturizing of an optical pickup. SOLUTION: This apparatus is made up of a first support member 8 one end of which is mounted on a balance weight 5 fixed on a lens holder 2 while the other end thereof is mounted on an intermediate member 6 to support an objective lens 1 movably in the radial direction of a disc and second support members 9a and 9b each one end of which is mounted on the intermediate member 6 while the other end on a fixed member 7 to support the objective lens 1 movably in the direction of the optical axis thereof. The objective lens 1 is located between the first support member 8 and the fixed member 7.

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 an optical disk device for optically writing or reading information on a disk-shaped recording medium.

[0002]

2. Description of the Related Art In an optical disk apparatus, an objective lens is moved in an optical axis direction (hereinafter referred to as a direction perpendicular to a recording medium surface) in order to correct a focus deviation or a tracking deviation due to an eccentricity due to a vertical movement of a warp of a disk-shaped recording medium. Focus direction F
And a radial direction parallel to the recording medium surface (hereinafter referred to as a tracking direction T).
Recording or reproduction is performed optically.

In recent years, CD players and MD players have been reduced in size and price, and the objective lens driving devices used in these players have been required to be further reduced in size and improved in mass productivity.

An example of the above-described conventional objective lens driving device will be described below with reference to the drawings.

FIG. 5 is a perspective view showing the structure of a conventional objective lens driving device, and FIG. 6 is a perspective view showing a supporting member. 5 and 6, reference numeral 52 denotes a lens holder, which includes an objective lens 51 and a focus coil 53.
a, 53b and the tracking coils 54a, 54b are fixed to form a movable part. Reference numeral 58 denotes a first support member formed of a plate-like elastic body such as phosphor bronze, and has one end fixed to the lens holder 52 and the other end fixed to the intermediate member 56. 59a and 59b are second support members formed of a plate-like elastic body, one end of which is fixed to the fixing member 57;
The other end is fixed to the intermediate member 56. The first support member 58 and the second support members 59a, 59b are connected to the intermediate member 56,
It is molded integrally with the fixing member 57 to form a support unit. The fixing member 57 is fixed to the base 60. Magnets 61a, 6 are provided on a base 60 made of a magnetic material.
1b is fixed, and the focus coils 53a and 53b and the tracking coils 54a and 54b form a magnetic circuit.

[0006] The operation of the objective lens driving device configured as described above will be described below.

The operation of driving the objective lens 51 in two directions, the focus direction F and the tracking direction T, in order to correct the focus shift due to the vertical movement of the warpage of the disk and the tracking shift due to the eccentricity will be described.

[0008] Forces in the Y direction are generated in the tracking coils 54a and 54b in directions opposite to each other by the electrodynamic converter including the tracking coils 54a and 54b and the magnets 61a and 61b. Since the lens holder 52 is cantilevered with respect to the intermediate member 56 by the first support member 58, the lens holder 52 rotates within the elastic deformation range of the first support member 58 by the force generated in the tracking coils 54a and 54b. The objective lens 51 moves in the X direction (tracking direction T). The driving in the focus direction F is performed by the electrodynamic converter including the focus coils 53a and 53b and the magnets 61a and 61b.
Generates a force in the Z direction. The second support members 59a and 59b are elastically deformed by this force, and the objective lens 51 moves in the F direction by the translational movement of the lens holder 52 in the Z direction.

As shown in FIG. 7, the objective lens driving device is mounted on an optical unit 62 on which light emitting and light receiving elements are mounted to constitute an optical pickup.

[0010]

However, in the above-mentioned conventional configuration, since the supporting member and the fixing member are biased in one direction in the Y direction with respect to the position of the objective lens 51, as shown in FIG. And the objective lens 5 of the optical pickup
There was a problem that Wa, which is the dimension from one center to the outer shape, became large.

SUMMARY OF THE INVENTION An object of the present invention is to provide an objective lens driving device capable of reducing the size of an optical pickup in consideration of such conventional problems.

[0012]

SUMMARY OF THE INVENTION The present invention provides a lens holder having an optical system including an objective lens for optically writing or reading information on or from a disk-shaped recording medium, and the disk-shaped recording medium. A first support member movably supporting the medium in a radial direction parallel to the recording medium surface, an intermediate member supporting the first support member, and a lens holder perpendicular to the recording medium surface. A second support member that supports the intermediate member so as to be movable in the optical axis direction in a different direction, and a fixing member that supports the second support member,
A magnetic circuit for driving the lens holder in the radial direction and the optical axis direction with respect to the fixed member is provided, and the optical system is an objective lens driving device disposed between the first support member and the fixed member.

[0013]

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

FIG. 1 is a perspective view of an objective lens driving device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is a sectional view thereof.

In FIGS. 1, 2 and 3, reference numeral 2 denotes a lens holder, and the objective lens 1 and focus coils 3a, 3
b and the tracking coils 4a and 4b are fixed, and the balance weight 5 is fixed to form a movable portion. 8
Is a first support member formed of a plate-like elastic body such as phosphor bronze. One end is fixed to a balance weight 5 fixed to the lens holder 2, and the other end is fixed to the intermediate member 6. 9a is a second support member formed of a plate-like elastic body, one end of which is fixed to the fixing member 7, and the other end of which is fixed to the intermediate member 6. The first support member 8 and the second support member 9a are composed of a balance weight 5, a fixing member 7, and an intermediate member 6.
To form a support unit A, and a second support member 9b forms a support unit B fixed to face the support unit A. Magnets 11a and 11b are fixed to a base 10 formed of a magnetic material, and the focus coils 3a and 3b and the tracking coils 4a and 4b constitute a magnetic circuit.

To assemble the objective lens driving device of the present embodiment, first, the focus coil 3 is attached to the lens holder 2.
a, 3b, the tracking coils 4a, 4b, and the objective lens 1 are fixed to form a movable unit, and the magnets 11a, 11b are fixed to the base 10 to form a fixed unit. The fixing member 7 of the support unit A is fixed to the base 10, and the lens holder 2 of the movable unit is fixed to the balance weight 5 of the support unit A. The support unit B is fixed to the intermediate member 6 and the fixing member 7 of the support unit A, and the apparatus is completed. As described above, the assembly between the units is all possible only by the movement in the Z direction.

The operation of the objective lens driving device configured as described above is basically the same as that described in the prior art of FIG. In the present embodiment, the balance weight 5 is rotated by the first support member 8 with respect to the intermediate member 8 in the tracking direction T, whereby the lens holder 2 fixed to the balance weight 5 is moved. It turns in the tracking direction T.

As shown in FIG. 4, since the objective lens 1 is located between the first support member 8 and the fixing member 7, the outer shape from the center of the objective lens 1 of the optical pickup equipped with this objective lens driving device is formed. The dimension Wb can be smaller than the dimension Wa of the conventional device shown in FIG.

As described above, the size of the optical pickup can be reduced by the objective lens driving device of the present invention, so that the size of the optical disk device on which the optical pickup is mounted can be reduced. Further, since each unit can be assembled from one direction, mass productivity is improved.

As the first support member, a conductive material such as phosphor bronze or beryllium copper can be used, and can be used to supply current to the focus coil and the tracking coil.

Further, the center of gravity of the movable portion can be made coincident with the center of rotation by the material and shape of the balance weight.
It is possible to reduce the displacement of the objective lens in the T direction due to the weight of the movable part when the apparatus is used in a state where the X direction of the apparatus is vertical.

[0022]

As is apparent from the above description, the present invention has an advantage that the optical pickup is arranged between the first supporting member and the fixing member, so that the size of the optical pickup can be reduced. Having.

[Brief description of the drawings]

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

FIG. 2 is a perspective view showing a support member of the objective lens driving device according to the embodiment.

FIG. 3 is a cross-sectional view showing the objective lens driving device of the embodiment.

FIG. 4 is a diagram illustrating an optical pickup equipped with the objective lens driving device of the embodiment.

FIG. 5 is a perspective view showing a conventional objective lens driving device.

FIG. 6 is a perspective view showing a support member of a conventional objective lens driving device.

FIG. 7 is a diagram showing an optical pickup equipped with a conventional objective lens driving device.

[Explanation of symbols]

 1, 51 Objective lens 2, 52 Lens holder 3a, 3b Focus coil 4a, 4b Tracking coil 5, 55 Balance weight 6, 56 Intermediate member 7, 57 Fixed member 8, 58 First support member 9a, 9b Second support Member 10, 60 Base 11a, 11b Magnet 12, 62 Optical unit 53a, 53b Focus coil 54a, 54b Tracking coil 59a, 59b Second support member 61a, 61b Magnet

Claims (5)

[Claims] 1. A lens holder on which an optical system including an objective lens for optically writing or reading information on or from a disc-shaped recording medium is mounted, and the lens holder is moved with respect to the recording medium surface of the disc-shaped recording medium. First support member movably supporting the first support member in a direction parallel to the recording medium, an intermediate member supporting the first support member, and an optical axis in a direction perpendicular to the recording medium surface. A second support member for supporting the intermediate member so as to be movable in a direction, a fixing member for supporting the second support member, and driving the lens holder in the radial direction and the optical axis direction with respect to the fixing member. An objective lens driving device, comprising: a magnetic circuit configured to perform the operation, wherein the optical system is disposed between the first support member and the fixed member. 2. The objective lens driving device according to claim 1, wherein the intermediate member, the first support member, the second support member, and the fixing member are integrally formed. 3. The second support member, the intermediate member, and the fixing member each include a pair of members, and include a first support member, and one of the second support member, the intermediate member, and the fixing member. And a support unit A in which the second support member, the intermediate member, and the fixing member are integrally formed.
The objective lens driving device as described in the above. 4. The objective lens drive according to claim 3, wherein a balance weight is further formed integrally with the support unit A, and the lens holder is connected to the balance weight. apparatus. 5. The apparatus according to claim 1, wherein a center of gravity of a movable portion including the optical system, the lens holder, and the balance weight is substantially coincident with a rotation center of rotation of the first support member. Item 5. The objective lens driving device according to Item 4.