Optical pick-up

Abstract

[Problem] An optical pickup that can incline an objective lens in the same direction as that of a bend of an optical disc is provided.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of an objective lens driving means of an optical pickup according to the present invention.

FIG. 2 shows magnetic flux density that affects focusing coils of the objective lens driving means shown in FIG. 1.

FIG. 3 shows a movement of the objective lens driving means shown in FIG. 1.

FIG. 4 shows a movement of the objective lens driving means shown in FIG. 1.

FIG. 5 shows a movement of the objective lens driving means shown in FIG. 1.

FIG. 6 shows another structure of the objective lens driving means according to the present invention.

FIG. 7 shows another structure of the objective lens driving means according to the present invention.

FIG. 8 shows a block diagram of an embodiment of an optical disc drive according to the present invention.

EXPLANATION OF LETTERS OR NUMERALS

• 1 . . . objective lens, 2 . . . lens holder, 3a, 3b . . . focusing coils, 4 . . . tracking coil, 6 . . . support members, 7 . . . fixing portion, 9 . . . yoke, 10 . . . inner yoke, 11 . . . magnets, 50 . . . objective lens driving means, 100 . . . optical disc drive, 101 . . . optical disc, 110 . . . optical pickup, 111 . . . light emitting device, 112 . . . photodetector.

Claims

1. An optical pickup, comprising: an objective lens;a lens holder that holds the objective lens;focusing coils attached to the lens holder;magnets disposed opposite to the focusing coils;a yoke to which the magnets are attached; andat least one or two inner yokes disposed opposite to the magnets via the focusing coils,wherein a cross-sectional area of the inner yoke disposed toward the outer periphery of an optical disc with respect to the objective lens is greater than a cross-sectional area of the inner yoke disposed toward the inner periphery of the optical disc with respect to the objective lens or wherein the inner yoke is disposed toward the outer periphery of the optical disc with respect to the objective lens alone.

2. The optical pickup according to claim 1, wherein the focusing coils disposed toward the inner periphery and the outer periphery of the optical disc with respect to the objective lens have a shape and size symmetrical to each other.

3. The optical pickup according to claim 2, wherein currents flowing through the focusing coils disposed toward the inner periphery and the outer periphery of the optical disc with respect to the objective lens are equal to each other.

4. The optical pickup according to claim 3, wherein the magnets disposed toward the inner periphery and outer periphery of the optical disc with respect to the objective lens have an identical shape, size, and properties.

5. The optical pickup according to claim 1, wherein the cross-sectional area of the inner yoke refers to the smaller one of the area of a cross section parallel to surfaces on which the focusing coils are attached and the area of a cross section perpendicular to the optical axis of the objective lens.