Optical keyboard with common light transmission members

PCT No. PCT/US82/00379 Sec. 371 Date Mar. 29, 1982 Sec. 102(e) Date Mar. 29, 1982 PCT Filed Mar. 29, 1982.A keyboard assembly (FIG. 1, 11) is constructed of first light transmission members (13) second light transmission members (15), a key actuation assembly (17) having a matrix of keybuttons (25), plural light source assembly (19) and plural sensor assembly (21). Each light source on assembly (19) is exclusively and sequentially energized causing its light to be transmitted through the first light transmission member (13) to be split up and deflected downwardly by the surfaces (43) and then rightwardly by the surfaces (45) to emanate through the surfaces (47) to enter the surfaces (49) of the second light transmission member. Actuation of a keybutton (25) causes its associated interrupter (29) to assume a light blocking position between the first light transmission member (13) and a second light transmission member (15). Light passing through the second light transmission member (15) to the sensor array indicates that none of the interrupters (29) have blocked the light path. This geometrical arrangement provides N key rollover detection with phantom key lockout and the light transmission members (13, 15) may be made of a single part or a single part for each row or column. Such parts provide common light transmission paths.