Improvement of dynamic characteristics for optical pickup actuator by magnetic circuit

Abstract As disk rotational speed of optical disk drives (ODD) increases, an optical pickup actuator has a high servo bandwidth for its focusing and tracking control to follow dynamic disturbances by high rotational speed in ODD. However, the servo bandwidth is limited by some vibration modes due to the flexibility of the moving part in the actuator. In this paper, the influence of the driving forces generated by VCM on excitation of flexible modes of the moving part in high frequency range is analyzed. Especially, in order to reduce the first flexible mode affecting the servo bandwidth, it is attempted to modify force distribution on coils. The magnetic simulation is performed by using finite element analysis, and compared with experimental results. Finally, it is shown that flexible mode vibration can be suppressed by proper design of magnetic circuit.