Patent ID: 6772088
Filing Date: 2004-08-03
Classification: G01D

Abstract:
A position transducer comprising:an absolute track in which micro-areas each represented by â€œ0â€  and those each represented by â€œ1â€ , when two types of micro-areas different in signal-selective physical property from each other are represented by either of two codes â€œ0â€  and â€œ1â€ , are laid in array to provide an n-bit code (n is a larger integer than 3); an absolute track head having (n+m) (m is a larger integer than 1) absolute track detectors laid in array oppositely to the absolute track and which is movable in relation to the absolute track to detect the physical property of the absolute track; an intra-micro-area position detecting means for detecting the position of each absolute track detector in the micro-area; a signal selecting means for selecting n ones of (n+m) signal outputs from the absolute track detectors on the basis of the result of detection by the intra-micro-area position detecting means; and a code deciding means for the n-bit code on the basis of signal output from an absolute track detector selected by the signal selecting means; a distance &lgr;1 between the first one and (n+m)th one of the absolute track detectors satisfying a requirement that (nâˆ’1)&lgr;+2&dgr;1 (where &lgr;>0 and &dgr;>0, &lgr; is the minimum resolution length of signal output from each absolute track detector and &dgr; in an unstable area is a length in the moving direction of the absolute track head); and a distance &lgr;2 between the absolute track detectors satisfying a requirement that 2&dgr;2