[OPTICAL REVIEW Vol. 18, No. 2 (2011) 218-223]
© 2011 The Japan Society of Applied Physics
High Uniform Illumination of Light-Emitting Diodes Lighting with Applying the Multiple-Curvature Lens
Allen Jong-Woei WHANG1, Shih-Min CHAO1, Cheng-Nan CHEN2, Yi-Yung CHEN1*, Horng-Ching HSIAO3, and Xi-Duo HU4
1National Taiwan University of Science and Technology, Department of Electronic Engineering #43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, R.O.C.
2National Taiwan University of Science and Technology, Graduate Institute of Electro-Optical Engineering #43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, R.O.C.
3National Taiwan University of Science and Technology, Department of Electrical Engineering #43, Sec. 4, Keelung Rd., Taipei 106, Taiwan, R.O.C.
4Dongguan University of Technology, Department of Electronic Engineering #1, University Rd., Guangdong Province, Dongguan City 523808, Songshan Lake, China
(Received August 5, 2010; Accepted January 5, 2011)
Light-emitting-diode (LED) sources will play a very important role in the future. Nowadays, there are many traditional light sources gradually being replaced by LED sources. From the viewpoint of illumination, different environments have the same requirement uniformity of illumination. The basic reason for this is to insure human comfort. Therefore, the promotion of illumination uniformity is an especially important key issue. In this article, we propose one effective design to improve the uniformity of illumination of LEDs with Lambertian radiation profiles by inserting into the lighting system, multiple-curvature lens. The enhanced illumination uniformity of LEDs, in this system, is due to energy redistribution by controlling the direction of incident light, using geometrical optics theory. Ray tracing was applied for the simulations required. Finally, the uniformity of illumination is 76.17% in LEDs using multiple-curvature lens, which is twice the uniformity of conventional LEDs. Furthermore, the phenomenon of overload in the multiple-curvature lens is reduced by increasing the numbers of rings on the lens. The overload is less than 0.02 lm in the case of lens designed with 23 rings.
Key words: uniform illumination, light emitting diodes (LEDs), Lambertian, lens design
*E-mail address: D9302305@mail.ntust.edu.tw