Flat-screen displays, such as those used in miniature televisions and computer displays normally produce a multicolour effect by means of microcolour filters used together with thin film transistors and liquid crystals, commonly also with fluorescent back-lighting. Since the observer is directly viewing the source of the light, the process involves the use of additive colour mixing and hence requires filters which incorporate the additive primary colours — red, green and blue (Chapter 2). Pigments are generally preferred to dyes for these applications because of their superior durability. The microfilters are manufactured by a process in which pigments of the appropriate three colours are deposited by vacuum sublimation on to a matrix of an appropriate design produced by photomicrolithography. The pigments for colour filter applications require the ability to sublime, good thermal stability and lightfastness, and appropriate spectral characteristics. Suitable pigments include the perylene 228 (red), copper phthalocyanine 229 (blue) and its octaphenyl derivative 230 (green) (Figure 10.4).
Pigments for Microcolour Filters
7 января, 2016 Pokraskin