Patent ID: 7278574

Claim:
A method of locating a position of a movable member, said movable member being movable along a path and having a surface, said movable member including a plurality of markings provided on said surface, said method comprising the steps of: exposing a portion of said surface of said movable member to light and detecting light emanating from said portion, said portion including a subset of said plurality of markings; generating a sense signal in response to said second radiation; determining a plurality of probability values associated with said sense signal, each of said plurality of probability values being associated with a corresponding subset of said plurality of markings; identifying said subset of said plurality of markings included in said portion of said surface of said movable member based upon at least some of said plurality of probability values; and identifying said position of said movable member along said path, said position corresponding to said identified subset of said plurality of markings included in said surface of said movable member.