High brightness, high resolution, projection CCRT

Abstract

A projection cathodochromic CRT (CCRT) has been developed that employs sodalite as the cathodochromic material. The construction of the CCRT is similar to that of the Advent Light Guide projection television tube. Images are written at one electron beam exposure and erased at a higher exposure that heats the screen material above its erase threshold. The optical configuration allows the projection of an image that is written on the cathodochromic screen surface nearest the electron gun. Compared to a conventional CCRT where the image appears on the surface most distant from the electron gun, the Light Guide optical arrangement offers distinct advantages of higher resolution, higher contrast, improved erasure quality, shorter erase time, and longer device lifetime. Over 8000, 9×7 dot matrix characters or detailed graphics can be displayed on a 6'-diagonal image screen with a white-area brightness of 300 fL and a contrast ratio in excess of 6:1. Characters can be written at a rate of 240 per second. Full screen erasure is accomplished in 2.8 seconds and selective character erasure requires about 1 msec.