Optical keyboard with geodesic optical elements

摘要

An optical keyboard having a plurality of keys formed on a sheet of transparent material used as light guide. Each key is a dome-shaped element such that the light beam launched into one end of the dome-shaped element spreads over at least part of the dome-shaped element and then converges at another end. The intensity of the re-focused light beam at the converging end can be sensed by a photosensor. When a key is pressed, the deformity on the dome-shaped element changes the focusing properties of the key and thus the sensed light intensity. The dome-shaped elements can be used as individual keys or as a group of keys arranged in a two-dimensional matrix.