Donald G Barnett

US Patent:

20020125412, Sep 12, 2002

Filed:

Mar 11, 2002

Appl. No.:

10/095542

Inventors:

Donald Barnett - West Chester PA, US

International Classification:

G02F001/01

US Classification:

250/225000

Abstract:

A rotary motion detection device for measuring the angle of rotation of a rotating shaft is comprised of an illumination source, an optical linear polarizer in the shape of a disk with central aperture there through for the slidable reception of a rotating shaft member, at least one stationary linear polarizer and at least one photodetector. The device is capable of providing absolute position information, infinite resolution of analog signals, ease of installation and environmental tolerance. The subject invention is further of small and light construction, employs a simple electrical interface, direct current supply voltage and offers vastly improved mechanical tolerances over the prior art. Additionally, concentricity of the rotating member, width of the non-contacting gap, axial endplay, runout and perpendicularity of the driving shaft are all inconsequential.