Proceedings PaperProject starlight: an approach to wide-range dimming for AMLCD backlighting
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AMLCD's used in cockpit applications are transmissive devices and therefore require backlighting. The nominal luminance at the front panel is 200 fl for sunlight and 0.1 fl for night vision goggle operation. This corresponds to a backlight luminance of approximately 5000 and 2.5 fl respectively. The industry has been struggling to provide this dimming ratio of 2000:1. Recently dimming ratios of 4000:1 and 8000:1 have been requested to provide better compatibility with night vision goggles. This is analogous to operation from sun light to star light. The problem with conventional lamp systems has been that the lamps stop fluorescing at low levels. This paper presents a summary of the methods developed to control conduction and hence luminance. When the methods were implemented, it was demonstrated that dimming ratios of 50,000:1 are achievable.