Cathodochromic CRT employing faceplate-deposited sodalite and electron-beam erase

Cathodochromic materials have the property that they change color upon excitation by an electron beam. While a portion of the coloration may be erased optically the remaining coloration can be removecl only by heating the material. Cathode ray tubes (CRT\´s) employing these materials as image screens offer long image storage, high resolution, high contrast, and gray scale. The construction of these devices is determined by the erase technique employed. Most previous device designs have the image screen deposited on a thin substrate which is suspended within the CRT envelope. Erasure is accomplished by raising the temperature of the target structure by either resistive, radiative, or electron-beam heating. A new cathodochromic cathode ray tube has been developed which employs a single electron gun for both writing and completely erasing a faceplate-deposited bromine-sodalite image screen. The device construction and erase technique are discussed. This device offers rugged and inexpensive construction, selective erase, and a "black-on-white" display.