ABSTRACT
The CD-ROM (compact disc-read only memory) drive reads data by focusing laser light on the plastic substrate and then detecting refl ected light as the disc rotates. The typical CD-ROM drive consists of the loading system, the feeding system, the printed circuit board (PCB), and the frame. The feeding system includes key mechanical components such as the optical pickup, the spindle motor, and the disc clamper. The optical pickup reads data written on the disc surface, and it includes a laser diode, an objective lens, a wire suspension, and a voice coil motor (VCM) actuator. As the demand for fast speed access and high track density is increased, the improvement of the speed and precision in the optical pickup is needed. There are basically three approaches to meet the demand: the development of robust servocontrollers, the modifi cation of the mechanism, and the applications of smart materials as new actuators.
