Improvements of properties and quality of LED displays

Photoluminescence spectra of LED displays were measured by the multichannel principle. A method to measure the dominant wavelength was developed and a color uniformity of + or - 1 nm is obtained. Linear arrays with 5 to 30 elements, two-dimensional arrays with 240 to 1600 elements and a round analog display with 90 LED were developed. Contrast enhancement by optical filters was investigated, and a visibility in 10 Klx ambients is achieved for neodymium and praseodymium doped filters.