Analysis and Validations of Fluid Dynamic Bearing for Spindle Motors of High-Density Optical Disc Players

Abstract

In recent times, the need to reduce the profiles of spindle motors in optical data storage devices without sacrificing their performance has become apparent. With the advent of high-density optical disc technology and reduction in the track pitch, spindle motors must have stable performance while tracking on narrow-pitch disks. In this paper, we present the structure and validations of the performance of a newly developed spindle motor (height 6.1 mm) using fluid dynamic bearing (FDB) for portable optical storage devices. The dynamic characteristics of the spindle motor before and after the accelerated life test are investigated experimentally. The noncontact phenomenon of the motor's shaft and FDB is also verified by using a laboratory-built apparatus. It was observed that the decrease in the axial repeatable runout (RRO) of the developed motor was up to 50% of that of the conventional spindle motor. All of the above validations prove that the developed FDB spindle motor has the potential for minimizing RRO, lowering acoustical noise, and improving reliability in portable optical storage devices.