Patent ID: 6693565
Filing Date: 2004-02-17
Classification: G01D

Abstract:
A position transducer comprising:an absolute track in which micro-areas each represented by â€œ0â€  and micro-areas each represented by â€œ1â€  when two types of micro-areas different in 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 natural number); an incremental track whose physical property varies in a constant cycle; an absolute track head having n 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 incremental track head having detectors opposite to the incremental track to detect the physical property of the incremental track; a sorting means for binarizing the values of signal outputs from the absolute track detectors to â€œHâ€  and â€œLâ€  based on a first threshold h and also to â€œHâ€  and â€œLâ€  based on a second threshold l (h>1) and then sorting the signal values into signal values having been judged as being â€œHâ€  or â€œLâ€  both when the signal outputs are binarized based on the first threshold h and when they are binarized based on the second threshold l and signal values having been judged as being â€œLâ€  when they are binarized based on the first threshold h and as being â€œHâ€  when they are binarized based on the second threshold l; an interpolation means for segmenting, within a micro-area, the position of the absolute track head in relation to the absolute track given by the n-bit code on the basis of the signal output from the incremental track detector; and a code deciding means for deciding the n-bit code based on the signal having been judged by the sorting means as being lower than l or over h and the result of the segmentation by the interpolation means.