Xerox Corporation

Michael G Demeny

Andrew Gabor

John C Dunfield

Apparatus is disclosed which is responsive to the movement of a movable element for generating a plurality of electrically phase-displaced signals containing information indicative of the direction, speed and distance of movement of the movable element. The apparatus comprises a plurality of position-displaced electrically conductive coils; a permanent magnet mounted adjacent each of the coils for producing a path of normally substantially constant magnetic flux adjacent each of the coils; and a flux varying device coupled to the movable element and responsive to the movement of the movable element for varying the level of the magnetic flux adjacent each of the coils in dependence upon the direction, speed and distance of movement of the movable element, whereby the resultant electromotive force induced in each of the coils defines the plurality of electrically phase-displaced signals. The flux varying device includes a rotor having a plurality of spaced teeth about the periphery thereof, the rotor being coupled to the movable element such that the rotor will rotate in a direction and at a speed corresponding to the direction and speed of movement of the movable element. The flux varying device also includes a plurality of pole pieces about which the coils are respectively wrapped, the pole pieces being mounted adjacent the path of travel of the rotor teeth such that a first gap of predetermined longitudinal extent is defined between the path of travel and each of the pole pieces, the longitudinal extent being perpendicular to the axis of rotation of said rotor.

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Fullerton, CA, United States of America

Michael G Demeny