A liquid-crystal display (LCD) is a flat-panel or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid do not emit light directly,[1] instead using backlight reflector to produce images in color monochrome.[2] LCDs are available arbitrary (as general-purpose computer display) fixed low information content, which can be displayed hidden. For instance: preset words, digits, and seven-segment displays, as digital clock, all good examples devices these displays. They use same basic technology, except made from matrix small pixels, while displays have larger elements. either normally on (positive) off (negative), depending polarizer arrangement. example, character positive LCD will black lettering background backlight, negative letters being backlight. Optical filters added white blue give them their characteristic appearance. used wide range applications, including televisions, monitors, instrument panels, aircraft cockpit indoor outdoor signage. Small screens common projectors portable consumer such cameras, watches, clocks, calculators, mobile telephones, smartphones. also electronics products DVD players, video game clocks. replaced heavy, bulky cathode ray tube (CRT) nearly applications. wider screen sizes than CRT plasma ranging tiny watches very large television receivers. slowly by OLEDs, easily into different shapes, lower response time, gamut, virtually infinite contrast viewing angles, weight for given size slimmer profile (because OLEDs single glass plastic panel whereas two panels; thickness panels increases but increase more noticeable LCDs) potentially power consumption only "on" where needed there no backlight). however, expensive due electroluminescent materials phosphors they use. Also phosphors, suffer burn-in currently way recycle OLED recycled, although technology required yet widespread. Attempts maintain competitiveness quantum dot marketed SUHD, QLED Triluminos, LED backlighting Quantum-dot enhancement film (QDEF) converts part red green, offering similar performance an at price, layer gives characteristics recycled. Since rarely image when static long e.g., table frame airline flight schedule sign. are, susceptible persistence.[3] The energy-efficient disposed safely can. Its electrical enables it battery-powered electronic equipment efficiently be. By 2008, annual sales televisions exceeded units worldwide, became obsolete most purposes.