Mechanisms of Minimum Skew Angle Actuation for Hard Disk Drives

Abstract

The utilization of voice coil motor (VCM) rotary actuator in hard disk drives (HDDs) results in skew angles between the read/write head and disk rotation direction. The system performance and achievable capacity of hard disk drives are excessively sensitive to the skew angle [1–3]. The difference in skew angle, between the ID to the OD can be as large as more than 30 degrees in conventional 3.5” and 2.5” VCM actuated HDDs. This paper presents three mechanisms, namely, a slant arm/suspension mechanism, a guider track mechanism, and a 4 link mechanism which can be designed to achieve minimum skew angle actuations for hard disk drives. The slant arm/suspension mechanism reduces the skew angle to ± 2 degrees in rotary actuated systems. The guider track mechanism further achieves the skew angle as zero degree theoretically. As an approximation of the guider track mechanism, the 4 link actuation mechanism reduces the skew angle to 0.4 degree. Their system dynamic behaviors are studied numerically using finite element modelling. Some of designs are prototyped and experimentally investigated.