Optical movement sensor using periodic pattern of slits - projects moving stripe pattern on to stationary masked photodetector giving electrical output proportional to distance moved

摘要

The movement sensor plate (2) is movable in a first plane and carries a pattern of slits or transparent sections (22) spaced regularly between opaque sections (23). It is illuminated by a LED (4) producing a prim. pattern of stripes (3) for projection by a lens (6) onto a photosensitive element (85) behind a periodic masking plate (83) fixed in a parallel plane. As the movable plate (2) is translated or rotated, the enlarged sec. stripe pattern (5) produced by the lens is scanned, producing a sinusoidal electrical signal (7). Movement speed can be determined by the signal frequency and position determination by counting resulting amplitude maxima. USE/ADVANTAGE - For measurement of rotary or linear movement. High resoln. achieved with sufficient spacing between moving and stationary slits.