Masaya Suwa

Evaluation system for residual vibration from HDD mounting mechanism

An evaluation system for calculating the residual vibration caused by a HDD (Hard Disk Drive) mounting system is presented. It contains both the elements for measurement and analysis. The PES (Position Error Signal) of an ideally balanced rigid rotary actuator depends on the rotational vibration of the HDD, specifically at lower frequencies. First, this evaluation technique obtains a measurement of the transfer function of the HDD rotational acceleration over actuator current. Next, using the measured power spectrum of the actuator in combination with the HDDs tracking error transfer function, the response of the entire HDD and mount system is calculated in the frequency domain. Finally the time domain system response is calculated by computation of the Inverse Fast Fourier Transform (IFFT) of the frequency response solution, assuming a random phase of the input force. Good correlation is obtained between measured and calculated system responses. Experimental result show that the dominant residual vibration is caused by the mounting mechanism response and that both the HDD and HDD mount system need to be evaluated and understood as a system, in order to achieve higher TPI (Track per inch) in the future.

A Study on Positioning Error Caused by Flow Induced Vibration Using Helium-Filled Hard Disk Drives

In this paper, we compare the positioning accuracy of helium- and air-filled drives. We report the PES spectra of the both drives and calculate the mechanical disturbance. The results reveal that almost all disturbances in higher rpm drives are flow induced vibrations and that disturbances in helium-filled drives are dramatically smaller. The experimental positioning error of helium-filled drives is less than half of that of air-filled drives. The static and dynamic fluid computations explaine these experimental results.

A Study on Positioning Error Caused by FIV using Helium Filled Hard Drives

We compared positioning accuracy of helium filled drives with that of standard air drives. We report the spectrums of PES and calculated mechanical disturbance. The results revealed that almost all disturbances in higher rpm drives are flow induced vibrations and that disturbances in helium drives are dramatically smaller. The experimental positioning error of helium drives is less than half that of usual air drives.