Patent ID: 6271661
Filing Date: 2001-08-07
Classification: G01D

Abstract:
An absolute position transducer, comprising:a scale member;a read head member, the read head member and the scale member movable relative to each other along a measuring axis;a code track position transducer comprising:at least one set of code track sensors formed on the read head member, each set of code track sensors including N sensors, where N is a positive integer greater than 1, anda code track formed on the scale member, the code track having a plurality of zones distributed along the measuring axis, at least one sensible element formed in at least some of the plurality of zones; anda signal generating and processing circuit electrically connected to each set of code track sensors;wherein:the sensible elements modulate an output of the N sensors of each set of code track sensors based on a relative position between the read head member and the scale member,the sensible elements are distributed on the scale member such that each zone is capable of producing one of a set of M output states in an overlying sensor where M is greater than 2, the zones forming a series of code elements extending along the measuring axis, each consecutive set of n code elements forming a non-binary code word, andeach non-binary code word defines an absolute position of the read head member relative to the scale member to a first resolution.