Mechanisms of Minimum Skew Angle Actuation for Hard Disk Drives

Zhimin He,Jianqiang Mou,Kheong Sann Chan,P Plapper,S Suhag,M Guo

doi:10.1051/matecconf/20164202002

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.

Highlights

We summarize 3 different mechanisms which attain minimum skew actuation for hard disk drives
For the slant suspension assembly, the actuator arm length is to be increased by about 30% of the original design, resulting in the in-plane first resonance frequency dropping by 20 to 30%, leading to degraded control bandwidth and shock resistance
The adverse effects of skew angle on areal density and track density Increase of actuator arm length by 30% resulting in arm in-plane and outof-plane resonance frequencies drop

Summary

Introduction

L0 stands for the distance between the pivot centre to the read/write element. In this case, the suspension length Ls is fixed, the slant angle E, will depend on the actual arm length, La. We optimize the arm length, La, such that the absolute skew angles from the inner diameter to outer diameter, are within r2q. When the suspension is slanted, the optimized slant angle E is calculated as 42q

Methods

Findings

Discussion

Conclusion