2008 年 2008 巻 53 号 p. 21-25
In many cases, the compact type hard disk drive (HDD) is employed in mobile devices, and a shockproof design is essential for this kind of application. A swing arm type positioning actuator is vulnerable to the vibration of arm bending modes excited by natural frequency when the shock impulse is imposed. In this paper, we studied different kind of swing arm type positioning actuators. Their mass and geometry are close each other, however, their vibration characteristics are quite different when the shock impulse is imposed. It turned out that the big difference in vibration response comes from the frequency interval of two arm bending modes in the actuator. The vibration system of three arm actuator consists of the main vibration system with top & bottom arm and the sub vibration system with the middle arm. We established the design method to minimize the frequency interval of two arm bending modes in order to improve the shockproof capability by utilizing the dynamic damping effect.