Contactless permanently illuminated keyboard has matrix of light emitting diodes and photodiodes identifying the key touched

摘要

A permanently illuminated keyboard comprises a matrix of LEDs (2) and photodiodes (3) so that operation of an individual key (1) interrupts the light beam between the given devices at the point of intersection beneath the key and identifies that key. Independent claims are also included for systems as above in which (a) the beams extend beneath the rows of keys and can pass through a transparent material; (b) the keyboard frame is opaque but can allow light to pass to the opposite diode.