Keyboard for data input into computing block, has keys designed in form of recesses in housing, and set of light sources directing crossed light beams toward photo sensors through apertures formed in portion of recesses

摘要

The keyboard has keys designed in the form of recesses (N) in a housing (G), and a set of light sources (L1-L34) for directing crossed light beams (1-34) toward photo sensors (F1-F34) through apertures formed in a portion of the recesses. The light beams intersect with each other at the center of the respective recesses in specific depth. The light beams are interrupted during the contact of a symbol present in the respective key so that electric signals, which qualify the symbol on the key, are modified in the appropriate photo sensors.