Browsing by Author "Lin, H. -W."

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A novel lens cap designed for the RGB LEDs installed in an ultra-thin and directly lit backlight unit of large-sized LCD TVs
(2008-02-01)
Chao, Paul C-P.
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Shen, C. -Y.
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Chiu, C. -W.
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Huang, J. -S.
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Kao, Y. -Y.
The objective of this study is to design a novel cone-shaped lens cap on LEDs in order to achieve high optical efficiency in an ultra-thin directly lit RGB LED backlight unit (BLU) for large-sized LCD TVs. The use of the novel lens cap could play the role of a diffuser, a low light-efficiency component in a BLU, in order to gain higher efficiency and simultaneously provide satisfactory uniformity in light distribution. The novel cone-shaped lens is coated with aluminum on the outside surface of the cone for mirroring effects to reflect most of the LED emitted light horizontally and then reflect the light at the BLU boundaries, and then, finally to the output plane. In this way, bright spots on the output plane of the BLU can be avoided, leading to increased uniformity. Simulations were conducted to design and optimize varied aspects of the designed lens and BLU, including the cone angle of the proposed lens and the LED spacing (pitch). To further achieve color balance, a known Genetic Algorithm is used to search for the optimal angular placement of each RGB LED, resulting in better color balance. Finally, a prototype BLU for large-sized 37-in. LCD TVs with the proposed lens was built to verify the expected performance.
Achieving color balance of a large sized BLU directly-lit by LEDs capped with customized optical lenses
(2008)
Chao, Paul C. -P.
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Shen, C. -Y.
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Chiu, C. -W.
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Huang, J. -S.
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Wang, C-L.
The objective of this study is to develop a high color balance thin RGB LED backlight unit (BLU) for large-sized LCD-TVs. Genetic Algorithm is employed to search the optimal angular placement of each RGB LED and gain the condition of better color mixing for achieving high color balance of BLU.
Intense terahertz emission from a-plane InN surface
(2008-03-10)
Ahn, H.
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Ku, Y. -P.
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Chuang, C. -H.
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Pan, C. -L.
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Lin, H. -W.
We report a significant enhancement in terahertz emission from the indium nitride (InN) films grown along the a axis (a-plane InN), relative to the InN films grown along the c axis. The primary radiation mechanism of the a-plane InN film is found to be due to the acceleration of photoexcited carriers under the polarization-induced in-plane electric field perpendicular to the a axis, which effectively enhances the geometrical coupling of the radiation out of semiconductor. In addition, azimuthal angle dependence measurement shows that the p-polarized terahertz output consists of a large angularly independent component and a weak component with a distinctive fourfold rotation symmetry. (c) 2008 American Institute of Physics.
Novel lens design for ultra-thin, high efficiency of light utilization, direct type RGB LED backlight module
(2007-01-01)
Shen, C. -Y.
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Chiu, C. -W.
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Chao, Paul C. -P.
;
Huang, J. -S.
;
Wang, C. L.
The objective of this study is to design a novel cone-shaped lens for achieving high optical efficiency for an ultra-thin, direct type RGB LED backlight unit (BLU). The usage of the novel lens could replace the commonly used diffuser plate for gaining higher efficiency and providing satisfactory uniformity of BLU. FMC7- 2