Goichi Akanuma

Improvement of Dynamic Characteristics for Symmetric-Type Slim Optical Pickup Actuator by Changing Coil Shape

As rotational speed and track density of disk media in optical disk drives increases, an optical pickup actuator must have a high servo bandwidth for its focusing and tracking control to follow disk fluctuations. In this paper, we propose an efficient method to improve control bandwidth of actuators through changing the shape of cross section of coils without redesigning structural parts

Radial and Tangential-Tilt Servo Using Four-Axis Actuator

A two-axis tilt servo using a four-axis object-lens actuator was developed. The four-axis actuator can tilt the object lens in the radial and tangential directions, and can move it to allow axial tracking or radial tracking. The tilt servo was applied on an optical disc system for next-generation digital versatile discs using a blue-violet laser, and the effect of disc-tilt compensation was determined experimentally. These experiments show that the tilt servo with the four-axis object lens actuator reduces tilt by 0.1 deg in the cases of a disc tangential tilt to 0.43 deg and a disc radial tilt to 0.47 deg.