Color tunable light‐emitting diodes with modified pulse‐width modulation |
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| Authors: | Jaehee Cho Qifeng Shan Jong Kyu Kim E Fred Schubert |
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| Institution: | 1. Department of Physics, Applied Physics, and Astronomy;2. Department of Electrical, Computer, and System Engineering;3. and Future Chips Constellation, Rensselaer Polytechnic Institute, Troy, New York 12180, USA;4. Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790‐784, Korea |
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| Abstract: | In this study, a color tunable light source, operated by a modified pulse width modulation method, is investigated. By utilizing this method along with anti‐parallel connected discrete light‐emitting diodes (LEDs) and two electrical terminals, a wide range of the chromaticity coordinates is attained and varied by electrical control. Using the combination of a blue LED and a phosphor‐converted yellow LED (blue LED plus yellow phosphor), the chromaticity range is varied by electrical control from pure blue to pure yellow. In addition, using the modified pulse‐width modulation method and a combination of white and red LEDs, white light with correlated color temperatures ranging from 5000 K to 2000 K is demonstrated. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) |
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| Keywords: | 07 60 Dq 81 05 Ea 84 37 +q 85 60 Jb |
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