The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 06, 2014
Filed:
Mar. 20, 2012
Qinghua Zeng, Freemont, CA (US);
Ellis Cha, San Ramon, CA (US);
Soramany Ka, San Jose, CA (US);
SAE Magnetics (HK) Lid., Shatin, N.T., HK;
Headway Technologies, Inc., Milpitas, CA (US);
Abstract
A method for determining the surface distortions of a disk in a spin-stand or single or multiple disk hard disk drive (HDD) utilizing a DFH type write head. A stepwise power curve is supplied to the DFH head, the head is flown over a chosen track on the disk, and the high frequency signal from a HDI sensor is analyzed in order to determine the step of an initial touchdown power and the step of a complete touchdown power as a function of individual sectors in a sector subdivision along a chosen track. The HDI sensor signal is averaged within each step of the power curve between these two steps and a Ratio variable,Ratio=(Max. amplitude)/(RMS amplitude)is calculated for each step and is averaged over each rotation of the disk during the step.