Design of Moving Magnet Type Optical Pickup Actuator with High Frequencies of the Flexible Modes

Data transfer rate and storage capacity are main criteria of the performance of the optical disk drive. The highest data transfer rate and the largest storage capacity is most desirable. To increase these performances, the actuator of the optical disk drive should have a high servo bandwidth to compensate the vibration of an optical disk. The servo bandwidth is limited by some flexible modes of the actuator, thus it is essential to increase the natural frequencies of the flexible modes. In this paper, we suggested a moving magnet type actuator having high frequencies of the flexible modes. Generally, the moving magnet type actuator has an advantage to increase the natural frequencies of the flexible modes because the moving magnet type actuator has simple structure and the Young`s modulus of magnet is high. However, large moving mass and inefficiency of EM(electromagnetic) circuit cut down driving sensitivities of the actuator. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and the natural frequencies of the flexible modes were improved by using DOE(design of experiments) for electromagnetic circuit and modifying the lens holder.