Optical Overlay Input Device for a Cathode Ray Tube
Original Publication Date: 1981-Nov-01
Included in the Prior Art Database: 2005-Feb-12
This article details a transparent display and data input combination that requires no more logic than a light pen and can be packaged within an existing CRT cover. The device is shown in a greatly enlarged cross section in the figure and comprises an optically clear elastomeric sheet 4 that has a cladding 5 of lower refractive index material on the operator's side. Between the material 4 and the face of the CRT is an air space provided by numerous optically clear spacer strips of lower index of refraction than the elastomeric material 4. The glass CRT envelope is shown as 1, and the phosphor coating as 2. Light from phosphors, caused to glow as a result of being scanned by the electron beam (not shown), exits from the surface of the CRT glass envelope 1, as shown.