doi:10.3850/978-981-08-6555-9_146

ABSTRACT

In order to meet the recent needs of portability and downsizing, the robustness against daily impact has become the important performance in mobile electronics. Most parts of the cellular phone should pass the drop test in which they fall from 1.5 m above the ground. The purpose of this test is to secure the phone from the case when it slips down user’s hand while talking on the phone. This paper studies the drop test for an automatic focusing (AF) actuator of a camera module in the cellular phone. The module is composed of voice coil motor (VCM) as an actuator and a leaf spring as a guide and suspension. While the conventional drop test has been carried out after fabricating real AF actuator, this paper proposes a model which can simulate the drop test based on finite element analysis. With this model, we investigate the stress acting on the clamping and the curved parts of leaf spring. The simulation shows that the stress over Von Mises criterion makes the leaf spring deformed permanently and as a result, the AF actuator malfunctioned. This method is useful not only to design and modify AF actuator without manufacturing the real product, but also to save time and cost during the development of new products.

Keywords: Cellular camera phone, Automatic focusing actuator, Drop test, Finite element method, Leaf spring.

© 2011 4M 2010 Organisers