A New Type Flat Moving-Coil Actuator for Small Form Factor Optical Disk Drive

We propose a new concept of flat moving coil type actuator designed for the application of 5mm height small form factor optical drive. The prototype of the actuator and optical platform is realized. The trend of the optical data storage is increase of the disk capacity and the miniature of the disk drive. The state-of-the-art of the optical disk drive for mobile application is in great demand (1). The thickness limitation of the drive and the actuator is the main challenge for such application (2, 3). In this paper, we propose a flat actuator that can be employed in the small form factor optical disk drive with 5mm height limitation. 2. Actuator configuration The configuration of the proposed actuator, which is a four-wire moving-coil type actuator, is shown in Figure 1. The moving coil type actuator has the advantage of lightweight and high DC sensitivity. And we use the FP coil (fine pattern coil) instead of winding coil for the benefit of easy assembly and flat shape. Two focusing coils and two tracking coils are integrated into single FP coil. Two multi-segment magnets pair are arranged to the top and bottom of the FP coil. Here, we use several unitary magnets to confirm the feasibility of our design as shown in Figure 2. This kind of arrangement helps to create a thinner actuator. When apply the driving current, the Lorenz force propel the actuator in the focusing and tracking direction separately. The size of the actuator is 12.6 × 8.0 × 2.6mm. The thickness of the actuator can be further decreased by the available of thinner magnets. The traveling range of the actuator is 0.4mm (P-P) in focusing direction and 0.2mm (P-P) in tracking direction.