Long-Life LEDs Target Rear-Projection TVs

The latest OSTAR LEDs from OSRAM Opto Semiconductor are specifically designed for rear-projection television (RPTV). The OSTAR Projection RPTV devices are mercury-free and deliver vivid color, high brightness, and long life, according to the company. OSRAM's underlying proprietary ThinFilm (red) and ThinGaN (green and blue) technologies ensure high efficiency and luminance. The LEDs are "surface emitters," which produce high light levels from a small emission area without the need for reflectors. Used with an appropriate imager, a system output of 300 lumens can be achieved in an RPTV.

Compared to the relatively short life spans of discharge lamps used in conventional RPTVs, OSTAR's average life is 20,000 to 50,000 hours. Also, discharge lamps need up to five minutes to warm up to full brightness. For RPTV, one red, one green, and one blue OSTAR are used, each with a special optic. Typical outputs are 750 lumens for red, 1250 for green, and 180 for blue. The LEDs are suitable for all RPTV technologies, including Digital Micro-Mirror Device (DMD), Liquid Crystal on Silicon (LCoS), or LCD. An RPTV with a 56-in. (diagonal) screen can achieve a luminance of up to 500 cd/m².