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Proceedings Paper

The optimized PWM driving for the lighting system based on physiological characteristic of human vision
Author(s): Ping-Chieh Wang; Chii-Maw Uang; Yi-Jian Hong; Zu-Sheng Ho
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Paper Abstract

Saving energy, White-light LED plays a main role in solid state lighting system. Find the best energy saving driven solution is the engineer endless hard work. Besides DC and AC driving, LED using Pulse Width Modulation (PWM) operation is also a valuable research topic. The most important issue for this work is to find the drive frequency and duty for achieving both energy saving and better feeling on the human vision sensation. In this paper, psychophysics of human vision response to the lighting effect, including Persistence of vision, Bloch's Law, Broca-Sulzer Law, Ferry-Porter Law, Talbot-Plateau Law, and Contrast Sensitivity, will be discussed and analyzed. From the human vision system, we found that there are three factors: the flash sensitivity, the illumination intensity and the background environment illumination, that are used to decide the frequency and duty of the PWM driving method. A set of controllable LED lamps with adjustable frequency and duty is fitted inside a non-closed box is constructed for this experiment. When the background environment illumination intensity is high, the variation of the flash sensitivity and illumination intensity is not easy to observe. Increasing PWM frequency will eliminate flash sensitivity. When the duty is over 70%, the vision sensitivity is saturated. For warning purpose, the better frequency range is between 7Hz to 15Hz and the duty cycle can be lower down to 70%. For general lighting, the better frequency range is between 200Hz to 1000Hz and the duty cycle can also be lower down to 70%.

Paper Details

Date Published: 7 September 2011
PDF: 9 pages
Proc. SPIE 8120, Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications V, 81200L (7 September 2011); doi: 10.1117/12.894503
Show Author Affiliations
Ping-Chieh Wang, I-Shou Univ. (Taiwan)
Chii-Maw Uang, I-Shou Univ. (Taiwan)
Yi-Jian Hong, I-Shou Univ. (Taiwan)
Zu-Sheng Ho, I-Shou Univ. (Taiwan)

Published in SPIE Proceedings Vol. 8120:
Photonic Fiber and Crystal Devices: Advances in Materials and Innovations in Device Applications V
Shizhuo Yin; Ruyan Guo, Editor(s)

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