Differential displacement optical sensor

摘要

Positional sensors receive light that has been reflected off a pair of complementary geometric patterns carried by a supporting, displaceable carrier surface. The sensors view the patterns through viewing windows as the carrier surface is displaced laterally, presenting differing portions of the patterns to the sensors. The patterns are shaped to produce outputs which, when their difference value is extracted, provide output signals that are a measure of the displacement of the carrier surface and in which common mode errors are minimized.