Design of optical pickup actuator suspension plates by the topology optimization method with the additional consideration of the plate orientation

In order to satisfy the stringent specification for the dynamic characteristics of modern optical pickup actuators, the topology design optimization of their suspension plates is presented. The specific design goal is to find the shape and orientation angle of the suspension plates that satisfy the desired fundamental eigenfrequencies in tracking, focusing and rolling directions. The key idea in this work is to consider plate orientation in addition to plate shape for the design optimization. The topology optimization considering the orientation angle yielded optimal suspension plates satisfying the target eigenfrequencies, which are not possible to obtain without considering it. For the topology optimization, the sensitivity analysis of the eigenfrequencies with respect to the suspension orientation angle was analytically derived. Numerical examples demonstrated the role of the plate orientation angle in designing optical pickup actuators having a wide spectrum of the fundamental eigenfrequencies.