Patent ID: 6170162
Filing Date: 2001-01-09
Classification: G01D

Abstract:
Rotary displacement measuring apparatus comprising:a shaft whose rotary displacement is to be measured, said shaft mounted to rotate about its long axis,a generally planar emitter disk mounted at its center on the shaft to rotate in the plane defined by the emitter disk and to develop and direct predetermined electric field patterns normally from an active side of the emitter disk, said emitter disk comprisinga disk mounted generally at its center to the shaft, andemitter element sections formed in a plurality of concentrically disposed, selectively segmented radial tracks on the active side of the disk to develop the electric field patterns in response to electric input signals, said emitter element sections being electrically coupled together to enable development of substantially uniform electric fields from all emitter element sections,a generally planar detector plate disposed in a fixed position about said shaft, generally parallel with the emitter disk on the active side thereof and disposed so as to enable a sensing means disposed on the detector plate to detect locations of the electric field patterns as the emitter plate is rotated and for producing output signals representing the electric field patterns detected and thus rotary displacement of the shaft, said sensing means comprising at least two absolute detectors and at least two incremental detectors, wherein the at least two incremental detectors produce output signals having a higher resolution of rotary displacement relative to the at least two absolute detectors, andmeans for supplying electric field input signals to the emitter element sections.