ABSTRACT
In cathodoluminescent (CL) display devices, light images are produced by tiny emitted elements (pixels), and image quality is directly related to CL generation. Chapter 3 described various advances in phosphor screens formed from commercial phosphor powders. CL screens inevitably exhibit flicker of images in small sizes that is not perceived by image viewers who watch images at a distance of five times the screen size; (e.g., 3 m). Furthermore, CL screens sometimes show the moiré effect. As a consequence of the brighter images on a phosphor screen, which are equivalent to daytime scenes, TV displays penetrate the illuminated living rooms of families. After 1980, personal computers (PCs) became prevalent on individual desktops, and PC images on phosphor screens are watched at the distance of distinct vision of the human eye (e.g., 30 cm away from the screen). By observing images at a short distance from the screen, the screen luminance of the PC decreases to the level of 150 cd m
, that is, half that of TV screens, resulting in that the moiré disappears from the CL phosphor screen. Then, image quality on CL phosphor screens, including flicker, smear, contrast, and color fidelity, is a serious problem for protecting the human eye from permanent damage. The image quality of CL phosphor screens relates to (1) the structure of the phosphor screen, and (2) the electrical and (3) physical properties of bulk of phosphor particles in the screens. Chapter 4 discusses these problems, which are definitely present in CL devices, for further improvement of the image quality of CL phosphor screens.
