Small form factor actuator design for camera phone lens systems

Abstract

This paper aims to suggest a concept design of a small form factor actuator for focusing or zooming systems of the camera phone lens. A traditional voice coil motor (VCM) type is used because it is very small, simple and reliable solution for the lens system. The topology optimization method is applied to suggest a structural design to maximize the actuating force without changing the input power and coils. The VCM system is generally composed of a permanent magnet (PM), a stator and voice coils; therefore, a simultaneous design of a PM and a stator is demanded. So far, many researches for the topology optimization of a ferromagnetic material have been achieved; however, very little has been done for the simultaneous design of a PM and a ferromagnetic material part. This study proposes a new methodology for the concurrent structural optimization for both parts. The optimization process must be formulated to support the sufficient force over whole stroke of the voice coil since the coil has a going and returning motion. The sensitivity calculation is accomplished by the adjoint variable method. Through the design process, a final concept design is suggested and its performance is verified using a commercial finite element analysis (FEA) package.