US Patent 7420890 Objective lens actuator and optical disk apparatus

An objective lens actuator of the present invention is an actuator capable of driving an objective lens which condenses a laser beam on an information recording surface of an optical disk, in each of a focusing direction, a tracking direction and a radial tilt direction. The actuator comprises a fixed unit including first and second magnets, and a moving unit which is arranged between the first and second magnets and which includes the objective lens, focusing coils, tracking coils, and a radial tilt coil. Each of the magnets is divided into four areas and being magnetized such that adjacent areas have opposite poles N and S, respectively. A direction of the magnetization is orthogonal to the focusing direction and tracking direction.