Modular touch sensitive data input device

Claim 1

A touch sensitive data input device for the screen of a cathode ray tube (CRT), comprising: a bezel formed to have a first recess and adapted to be mounted to said screen with said recess exposed and also having an aperture within said first recess through which the screen is exposed; a transparent backing plate mounted to the bezel within the first recess so as to cover said aperture, the backing plate being smaller than the first recess to thereby establish a small transverse play between the backing plate periphery and a wall defining the recess therearound; a rear transparent sheet element located against said backing plate such that contact therebetween occurs only between a rear surface of the rear sheet element and an adjacent front surface of the backing plate, a front surface of said rear sheet element containing a plurality of parallel, transparent, electrically conductive first strips said rear sheet element and said backing plate being respectively formed of materials having different thermal coefficients of expansion, said rear sheet element being retained against but not secured to said backing plate to avoid wrinkling of said rear sheet element on said backing plate in response to ambient temperature changes due to differential expansion therebetween because of said different thermal coefficients of expansion of said element and plate; a front transparent sheet element facing said rear sheet element and containing a plurality of parallel, electrically conductive second strips disposed to be orthogonal to said first strips, said first and second strips being electrically insulated and closely shaped apart from each other until external pressure applied to the front sheet establishes an electrical connection between particular ones of said first and second conductive strips at the point of contact; and a frame located over said front sheet element and secured to said bezel.