Color temperature tunable white light LED packaged with omni-directional reflector

• Main Authors: Chun-lin Lu, 呂俊霖
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/83952013133752877987

碩士 === 國立臺灣科技大學 === 光電工程研究所 === 97 === This work studied the UV-excited white light LED packaged with omni-directional reflector(ODR) and proposed the color temperature tunable white light LED based on InGaN chips. We controlled the composition and concentration of phosphors blend layer by means of Taguchi Method and achieved the standard white light. Since the chosen UV chip resulted in the UV leak, this study proposed the package structure with ODR to solve the problem. We designed and fabricated the ODR can block the UV light in the lead frame for the practical application, and the visible light escaped from the packaging structure of white light LED. At a constant applied current of 20 mA, the chromaticity color coordinates, CCT, Ra were (0.325, 0.327), 5851K and 96.47, respectively. The results were close to that of CIE standard D65 illumination. The angular distribution of the radiant intensity of a UV leak was measured and the transmittance of UV light was under 10%. We confirmed the ODR can prevent UV leak from the device. The ODR packaging structure can enhance the average luminous intensity 15% without any damage on the electronic properties of LED. This study proposed a violet light chip(λpeak =410 nm) and a blue light chip(λpeak =465 nm) combined with the above structure of UV-excited white light LED, and we can achieve a color temperature white light LED by controlling the concentration of phosphor and driving current. Specifically, the color coordinate for the light source made was (0.3347, 0.3384), the correlated color temperature was 5398 K, the CRI had a value of 81. The tunable range of CCT was 3137 K~8746 K. It has included the application in the life. Although the uniformity occurred to this case, we improved the problem by roughing the top glass of the packaging structure. The emitting angle of white light can be increased from ±10 degrees to ±80 degrees, and the CCT was at the range of 6284 K ~7499 K in ±70 degrees. The increasing uniformity can make it practical in the future.