Demonstration of a magnetic angular position sensor with ultra-high resolution and accuracy

Abstract

In this study, a magnetic angular position sensor with 160,000 pulses/rev and 0.4 in. of the accuracy is obtained using a longitudinal disk, magnetoresistive (MR) sensors and a new method of formatting magnetic poles on the disk. The magnetic poles are formatted by a thin film inductive head with 6 μm of trackwidth and 0.7 μm gap length. Angular position signals are reproduced by two MR sensors which are commercial MR heads with 4 μm trackwidth and 0.6 μm gap length maintained in phase quadrature with each other. In order to format equally all magnetic poles on the disk, the central frequency of the writing signal must be equal to the central frequency of the speed of disk and the steadiness of the disk speed and writing frequency must be as high as possible.