Seek actuator for optical recording

Abstract

An apparatus for optically reading or recording information on an optical disc which is rotatable about an axis of rotation. The apparatus includes a frame, a carriage movable relative to the frame along a path orthogonal to the axis of rotation, and a carriage drive for driving the carriage along the orthogonal path. Specific portions of the carriage drive are mounted on the carriage so that the carriage and the mounted portions define a center of carriage mass. An objective lens having an optical axis along a Z-axis and a center of lens mass is provided in an objective lens holder. The holder is movable relative to the carriage and receives a beam of light traveling along an X-axis. Flexures are provided for movably supporting the objective lens holder relative to the carriage. The flexures each have a hinge point within an XZ plane so that movement of the lens holder is provided by hinge action at the hinge points. A focus drive is provided for driving the lens holder which moves the objective lens along its optical axis. The focus drive and the objective lens holder define a center of fine motor mass. The center of fine motor mass, the center of carriage mass, and the center of lens mass are substantially coincident on the optical axis so that when the objective lens holder is moved in a tracking direction, moments about the Z-axis are minimized.