ABSTRACT
In the wake of commercialization of LEDs in the 1960s, their rst applications appeared as colored indicator lamps in electrical and electronic devices. Afterwards, LEDs began to be used in alphanumeric displays for providing information in the form of characters, consisting of numbers or letters, in electronic calculators and digital watches. is application eld was captured by liquid crystal displays (LCDs) that used liquid crystal cells, which change reectivity in an applied electric eld. Again, when high-brightness LEDs came to the market in 1980s, the scenario transformed with their permeation into all areas of articial light production. e most popular application niches of LEDs are power signage, displays, and illumination. Other areas are medicine, sensing, and measurements. In the context of applications, LEDs are sometimes classied as small and large LEDs (Table 23.1).
