Influence of UV-IR filter in LCD projection system

摘要

Projection system utilized liquid crystal display (LCD) module has become a modern trend of large screen viewing system. The display is normally ranged from 40 to 100 inches in diagonal. This is a great advantage over conventional CRT display that is very difficult to have size more than 40 inches. The LCD projection system consists of different optical components in order to have high intensity of illumination as well as good image quality. The arrangement of main optical components is typically following; light source, cold mirror, condenser, UV-IR filter, polarizer, then objective lens. In the work, we have studied the influence of UV-IR filter spectrum toward the picture quality. Three kinds of UV-IR filters with different spectrums were used. The selection rules of UV-IR filter are based on emitting spectrum of metal halide lamp, and the transmitting spectrum of LCD module. The optical performances of different spectrum in UV-IR filters were analyzed with NTSC standard in CIE (U,V) chart. Our result indicated that the chromaticity and illumination efficiency were varied by spectrum profile of UV-IR filter.