Patent ID: 6679126
Filing Date: 2004-01-20
Classification: G01L

Abstract:
A system for detecting angular displacement in a shaft, the system comprising:a first rotating member, having a first slit pattern therethrough, and being affixed to the shaft; a second rotating member, having a second slit pattern therethrough, and being affixed to the shaft; a light source positioned on a side of said first rotating member opposite said second rotating member; a light detector positioned on a side of said second rotating member opposite said first rotating member such that light from said light source which would otherwise be incident on said light detector is substantially blocked by said first and second rotating members, except for light which passes through said first and second slit patterns; wherein said first and second slit patterns are adapted to create a pattern of light incident on said light detector that varies according to an angular position of said first rotating member relative to said second rotating member; and wherein said light detector is adapted to produce a position signal responsive to a position of said pattern of light incident on said light detector.