Objective lens driving device, control circuit, optical disc device and objective lens driving method

An objective lens driving device, comprising:

• an objective lens;
• an objective lens holder that holds the objective lens;
• a plurality of elastic supporting members that support the objective lens holder;
• a tracking driving member configured to drive the objective lens holder in a tracking direction;
• a focus driving member configured to drive the objective lens holder in a focus direction;
• a tilting correction member configured to tilt the objective lens holder with respect to an optical axis passing through the objective lens;
• a tracking control circuit configured to drive the tracking driving member using a tracking driving signal generated on the basis of a tracking error signal;
• a focus control circuit configured to drive the focus driving member;
• a tracking position detection portion configured to detect a position of the objective lens holder in the tracking direction;
• and
• a tilting control circuit configured to drive the tilting correction member according to the position detected by the tracking position detection portion so as to cancel out a tilting force of the objective lens holder generated by the focus driving member;
• wherein:
• the objective lens, the objective lens holder, the tracking driving member, the focus driving member and the tilting correction member are included in a movable portion, and when the movable portion is moved in the tracking direction, a center of gravity of the movable portion is spaced apart from a center of a driving force of the focus driving member,
• the tilting control circuit is configured to drive the tilting correction member according to the position detected by the tracking position detection portion and supply the tilting correction member with a current so as to cancel out a tilting force of the objective lens holder induced by the displacement of the center of the driving force of the focus driving member from the center of gravity of the movable portion caused by the moving operation of the movable portion in the tracking direction, and
• the tilting control circuit includes a multiplier configured to multiply the tracking driving signal by a scaling factor K which is adjusted so that the tracking error signal has a maximum amplitude.

A control circuit, comprising:

• a tracking control circuit configured to drive a tracking driving member driving an objective lens holder, which is supported on a plurality of elastic supporting members and holds an objective lens, in a tracking direction using a tracking driving signal generated on the basis of a tracking error signal;
• and
• a tilting control circuit configured to drive a tilting correction member, the tilting correction member being configured to tilt the objective lens holder with respect to an optical axis passing through the objective lens using the tracking driving signal generated in the tracking control circuit so as to cancel out a tilting force of the objective lens holder generated by the tracking driving member;
• wherein:
• the objective lens, the objective lens holder, the tracking driving member, and the tilting correction member are included in a movable portion, and a center of gravity of the movable portion is spaced apart from a center of a driving force of the tracking driving member,
• the tilting control circuit is configured to drive the tilting correction member using a signal yielded by multiplying the tracking driving signal by a specific scaling factor K and supply the tilting correction member with a current so as to cancel out the tilting force of the objective lens holder induced due to a positional displacement between the center of gravity of the movable portion and the center of the driving force of the tracking driving member, and
• the tilting control circuit includes a multiplier configured to multiply the tracking driving signal by the scaling factor K which is adjusted so that the tracking error signal has a maximum amplitude.

A method of driving an objective lens, comprising:

• driving a tracking driving member so as to drive an objective lens holder, which is supported on a plurality of elastic supporting members and holds an objective lens, in a tracking direction using a tracking driving signal generated on the basis of a tracking error signal;
• and
• driving a tilting correction member so as to tilt the objective lens holder with respect to an optical axis passing through the objective lens using the tracking driving signal from the tracking driving member so as to cancel out a tilting force of the objective lens holder generated by the tracking driving member;
• wherein:
• the objective lens, the objective lens holder, the tracking driving member, and the tilting correction member are included in a movable portion, and a center of gravity of the movable portion is spaced apart from a center of a driving force of the tracking driving member,
• a tilting control circuit drives the tilting correction member using a signal yielded by multiplying the tracking driving signal by a specific scaling factor K and supply the tilting correction member with a current so as to cancel out the tilting force of the objective lens holder induced due to a positional displacement between the center of gravity of the movable portion and the center of the driving force of the tracking driving member, and
• the tilting control circuit includes a multiplier that multiples the tracking driving signal by the scaling factor K which is adjusted so that the tracking error signal has a maximum amplitude.