Electrochromic variable transmission glass for picture tubes

This paper deals with the question of how the picture quality of cathode ray tubes (CRTs) can be improved significantly with the help of electrochromic variable transmission glass. With the popularity of daytime television viewing and the widespread use of PC monitors in the office, CRTs should render good contrast and colour under day-light conditions. State-of-the-art CRTs therefore have dark screens with transmissions down to 35%. This dark glass, however, deteriorates the picture quality at low illumination, a typical condition when viewing in the evening. Moreover, it leads to an increased energy consumption. For optimum picture quality under both illumination conditions and to prevent unnecessary energy use, variable transmission systems are needed on transparent CRT screens. All solid state electrochromic coatings, in which the intercalation compounds are sandwiched between two transparent electrodes to form a single stack, show very promising characteristics for this novel application. The fundamentals of contrast and colour rendering of a CRT in relation to the glass transmission and the practical application of electrochromic coatings on CRTs are elucidated in more detail in this paper. (C) 1999 Elsevier Science Ltd. All rights reserved.