Patent ID: 6489761
Filing Date: 2002-12-03
Classification: G01D

Abstract:
An analog angle encoder comprising:a non-magnetic stator; at least one magnetosensitive device connected with said stator, said at least one magnetosensitive device having a sensing surface; a non-magnetic rotor, wherein one of said stator and said rotor is rotatable about a rotation axis, wherein said sensing surface is oriented parallel to said axis of rotation; and a pair of magnets attached to said rotor, said pair of magnets being disposed in mutually diametrically opposed relation relative to the axis of rotation, wherein said pair of magnets have mutually facing pole faces and mutually facing away pole faces, said mutually facing pole faces being of opposite polarity and provide a magnetic field passing through said at least one magnetosensitive device at an orientation normal to said axis of rotation, said mutually facing away poles being free of a ferromagnetic return path; wherein the magnetic field is substantially uniform over an area at least as large as said sensor surface; and wherein said stator is generally cup-shaped comprising an outer annulus, a disk connected to said annulus and a central post connected to said disk in concentric relation to said outer annulus, said at least one magnetosensitive device being embedded in said central post at a location concentric in relation to said annulus; wherein said rotor is generally ring-shaped and captured between said central post and said outer annulus, said rotor being rotatable about the rotation axis; and wherein each magnet of said pair of magnets is a permanent magnet.