Eliminating hotspots in a multi-chip LED array direct backlight system with optimal patterned reflectors for uniform illuminance and minimal system thickness

Byungwook Kim, Joongeok Kim, Won Suk Ohm, Shinill Kang

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

We propose an optical design process that significantly reduces the time and costs in direct backlight unit (BLU) development. In it, the basic system specifications are derived from the optical characteristics of RGB light-emitting diodes (LEDs) comprising the BLU. The driving currents are estimated to determine the theoretical RGB flux ratio for a desired white point. The number of LEDs needed to produce the target luminance is then calculated from the combined optical efficiencies of the components. Last, an appropriate array configuration is sought based on the illuminance distribution function for meeting the target uniformity. To showcase the design process we built two 42-inch triangular cluster arrays of 40 × 16 LED elements. When a flat reflective sheet was used, the minimum thickness required of the system to satisfy the target uniformity was 30 mm. Introducing a patterned reflective sheet removed hotspots that resulted from reducing the system thickness without the aid of additional optical components. Using an optimized patterned reflective sheet, reduction in system thickness as much as 5 mm was possible.

Original languageEnglish
Pages (from-to)8595-8604
Number of pages10
JournalOptics Express
Volume18
Issue number8
DOIs
Publication statusPublished - 2010 Apr 12

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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