Patent ID: 6945126
Filing Date: 2005-09-20
Classification: B62D,G01L

Abstract:
1. A rotation sensor mounted on a rotatable shaft to detect a rotation angle of said shaft, comprising: first and second members each surrounding said shaft, being disposed separately from each other along an axis of said shaft, and relatively rotating along with rotation of said shaft; a slip ring carried on said fist member and extending concentrically with said shaft, said slip ring being made of a conductive metal; a film formed on said slip ring, the film being made of a synthetic resin having conductivity; and a conductive brush carried on said second member and slidably contacting said slip ring either directly or through said film, wherein: a sliding-contact position between said brush and said slip ring is displaced in a circumferential direction of said slip ring according to the rotation angle of said shaft when said first and second members relatively rotate; wherein said slip ring has a commonly used zone in which there exists said sliding-contact position with high frequency and a non-commonly used zone in which there exists said sliding-contact position with lower frequency than said commonly used zone; and wherein said film is formed on a part of said slip ring which includes said commonly used zone of said slip ring.