Fabrication of gapless dual-curvature microlens as a diffuser for a LED package

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

28 Scopus Citations
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Author(s)

  • C. T. Pan
  • M. F. Chen
  • P. J. Cheng
  • Y. M. Hwang
  • S. D. Tseng

Detail(s)

Original languageEnglish
Pages (from-to)156-167
Journal / PublicationSensors and Actuators, A: Physical
Volume150
Issue number1
Online published24 Dec 2008
Publication statusPublished - 16 Mar 2009
Externally publishedYes

Abstract

The light-emitting diode (LED) has been the subject of much interest in the role of a backlight module for liquid crystal displays (LCDs). However, a traditional LED lamp is a point-light source, and so is not suitable for use in large LCD panels. This study presents a new packaging method for LEDs, which uses a gapless dual-curvature microlens array (GDMLA) to improve its ability to illuminate a panel. GDMLAs of different dimensions were simulated and fabricated in order to examine their light luminance and uniformity. Commercial optical simulation software, "Tracepro", was used to obtain a GDMLA of optimized geometry and dimensions. Based on the simulated data, a GDMLA mold was first fabricated using a LIGA-like process (Lithographie Galvanoformung Abformung, LIGA); this was known as the first mold. In this study, the first mold was obtained using a nickel cobalt (Ni-Co) electroplating process. In order to obtain a highly accurate and strong mold, a bulk metallic glass (BMG) alloy, Mg58Cu31Y11, was chosen as the material for the second mold, which exhibits excellent forming ability and high hardness. The pattern of the first mold was replicated onto BMG by hot-embossing, and the shrinkage between the first and the second mold was less than 0.2%. Next, the pattern of the GDMLA on the second mold was replicated onto ultraviolet (UV)-curable resin, producing the final optical film for a LED package. The shrinkage between the second mold and the UV-cured optical film was less than 0.4%; this means that the process exhibits a high replication ability. The fabricated GDMLA had the characteristics of dual curvatures and a high fill-factor of 100%. The light uniformity of the LED package with the GDMLA optical film was measured, and the results demonstrated that the GDMLA is a good optical device for use in LED packages. In addition, the relationship between the simulation and experimental results is assessed and discussed. 

Research Area(s)

  • BMG, Dual-curvature microlens, Hot-embossing, LED, Light uniformity, UV-cured

Citation Format(s)

Fabrication of gapless dual-curvature microlens as a diffuser for a LED package. / Pan, C. T.; Chen, M. F.; Cheng, P. J. et al.
In: Sensors and Actuators, A: Physical, Vol. 150, No. 1, 16.03.2009, p. 156-167.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review