Johnson Ralph G, Fryberger David: Touch actuable data input panel assembly. June 27, 1972: US3673327 (167 worldwide citation)

A panel positioned over the face of a cathode-ray tube with transmitters mounted along two adjacent edges of the panel to generate beams, either Rayleigh wave beams or light beams, that propagate through the panel to detectors mounted along opposite panel edges. The beams are directed to intersect i ...