25.3: LED Array with Recycling for High‐Power Projector Applications

Abstract

AbstractLEDs are still not bright enough, compared to arc lamps, for high power projector applications. For high power applications, multiple LEDs are required to increase the total light output with the same amount of increase in etendue. Even with the use of larger imaging panels with larger etendue values, the total output of the LED projector is still not sufficient for cinema projection applications. With recycling technology, the etendue of the LED can be reduced with increased brightness. This paper describes two systems with an array of 7 LEDs with recycling, such that the combined etendue matches with standard imagers for cinema projector applications. The first system uses a single array of 7 white LEDs with up to 9,500 lumens of white light can be generated at an etendue of 70, which is the etendue value of standard cinema projector systems. A screen lumen of over 3,300 lumens can be achieved. The second system uses 3 independent arrays of 7 red, green and blue LEDs combined producing to 18,500 lumens of white light at an etendue of 70. A screen lumen of over 6,500 lumens can be achieved from a single projector. Using two such projectors with combined output of over 13,000 lumens, the system can be used in small cinema replacing xenon based system or laser based systems.