Objective lens driving apparatus

An objective lens driving apparatus comprising:

• an objective lens (1) for focusing a light beam on a disc for recording and reproducing information on said disc;
• a lens holder (2) for holding said objective lens;
• a plurality of supporting members (3a-3d) for supporting said lens holder so as to be movable in a focusing direction (Fo) along the optical axis of said objective lens, and also in a tracking direction (Tk) of a radial direction of said disc;
• a coil assembly (34a) having a focusing coil (35a) formed so as to include a line of intersection of the plane of the focusing coil and the plane being perpendicular to the tracking direction (Tk) and including the optical axis of said objective lens as a center line and at least two tracking coils (36, 37) lies on both sides in the tracking direction of said focusing coil on a plane including a focusing direction and a tracking direction of said lens holder;
• and
• a magnet assembly (38a) including:
• a first magnet (38a1), disposed opposite to said focusing coil, and having magnetic poles arranged at positions opposite to winding portions of said focusing coil extending in a direction intersecting said focusing direction;
• and
• two second magnets (38a2, 38a3), disposed opposite to said tracking coil, and having magnetic poles arranged at positions opposite to winding portions of said tracking coils extending in a direction intersecting said tracking direction.

An objective lens driving apparatus comprising:

• an objective lens (1) for focusing a light beam on a disc for recording and reproducing information on said disc;
• a lens holder (2) for holding said objective lens;
• a plurality of supporting members (3a-3d) for supporting said lens holder so as to be movable in a focusing direction (Fo) of the optical axis direction of said objective lens, and also in a tracking direction (Tk) of a radial direction of said disc;
• a coil assembly (64a) having a focusing coil (65a) asymmetrically with respect to the line of intersection of the plane including the focusing direction and the tracking direction of said lens holder and the plane including the optical axis of said objective lens and being perpendicular to said tracking direction, and at least one tracking coil (66a) asymmetric with respect to said line of intersection, a magnet assembly (68a), disposed opposite to said focusing coil, having magnetic poles opposite to plural winding portions of said focusing coil intersecting to the focusing direction with inverse magnetic poles with each other, and having magnetic poles opposite to plural winding portions of said tracking coil intersecting to the tracking direction with inverse magnetic poles with each other.

An objective lens driving apparatus comprising:

• an objective lens (1) for focusing a light beam on a disc for recording and reproducing information on said disc;
• a lens holder (2) for holding said objective lens;
• a plurality of supporting member (3a-3d) for supporting said lens holder so as to be moveable in a focusing direction (Fo) of the optical axis direction of said objective lens, and in a tracking direction (Tk) of a radial direction of said disc;
• a coil assembly (54a) having a tracking coil (56a) formed so as to include a line of intersection of the plane of the focusing coil and the plane being perpendicular to the tracking direction (Tk) and including the optical axis of said objective lens as a centerline, and at least two focusing coils (55a and 55b) arranged on both sides of said tracking coil in the tracking direction on a plane containing the focusing direction and the tracking direction of said lens holder;
• and
• a magnet assembly (8a) having a first magnet (8a1) and a second magnet (8a2) disposed opposite to said at least two focusing coils and having two magnetic poles facing to winding portions of said focusing coil extending in a direction intersecting said focusing direction;
• wherein
• said first magnet and said second magnet are disposed adjacent to each other along a center line parallel to focusing direction of said tracking coil, and a magnetic pole of each magnet forming L-shaped region so that inverse two magnetic poles are disposed opposite to winding portions of said tracking coil extending in a direction intersecting said tracking direction.