Sensor apparatus and method for sensing angular rotation of an object using light reflected off a rotor and bifurcation compensation

• Main Author: COOPER STEPHEN R. W
• Format: Patent
• Language: English
• Published: 17.12.2002
• Edition: 7
• Subjects: ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVEREDIN A SINGLE OTHER SUBCLASS; MEASURING; MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR; PHYSICS; TARIFF METERING APPARATUS; TESTING

An apparatus (100) for sensing angular rotation includes a rotor (102) that is rotatable about an axis (104). The rotor (102) has an outer periphery (e.g., cylindrical outer sidewall 106) with a plurality of reflective facets (e.g., 108A-108J). Each juncture between each adjacent pair of the facets (e.g., 108A and 108B) defines a vertex (e.g., 125A). A light source (118) emits a light beam (120) onto the rotor (102). The light beam (120) is reflected by the facets (e.g., 108B) and occasionally bifurcated by the vertices (e.g., 125A). A light detector (126) detects light from the reflected light (124). The light detector (126) provides a detector signal (116) indicative of the angular rotation of the rotor (102). Compensation circuitry (134, 138) compensates for bifurcation of the reflected light (124) and provides a compensated output signal (140) indicative of angular rotation of the rotor (102).