Inverted-cone-lens encapsulant with gradient surface for ring-remote-phosphor structure

Ming Te Lin, Shang Ping Ying, Ming Yao Lin, Kuang Yu Tai, Sheng Chieh Tai, Chih Hsuan Liu, Jyh Chen Chen, Ching Cherng Sun

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The ordinary ring-remote-phosphor structure consisting of an inverted-cone-lens encapsulant and a surrounding ring-remote-phosphor layer reduces the probability of the backward light from the phosphor layer to the absorptive light-emitting diode (LED) chip and then increases the package extraction efficiency. However, some of the blue light emitting from the LED chip impinges on the inverted-cone-lens surface and then escapes without hitting the ring-remote-phosphor layer. The blue light leakage from the inverted-cone-lens surface is a serious problem for the ring-remote-phosphor structure devices in use, because it will lower the actual illumination effects and result in discomfort for the eyes. In this paper, we discuss the predominant factors of the blue light leakage from the inverted-cone-lens surface and propose an improve ring-remote-phosphor structure that utilizes an inverted-cone-lens encapsulant with gradient surface to decrease the blue light leakage. Ray-tracing simulations are performed to analyze the blue light leakages from the ordinary and improved inverted-cone-lens encapsulants in the ring-remote-phosphor structures. The simulation results show that the improved inverted-cone-lens encapsulants get almost no blue light leakage from the inverted-cone-lens surface directly and then lessen the discomfort for the eyes. Our results further demonstrate that the improved ring-remote-phosphor structure device will have higher angular color uniformity than the ordinary one.

Original languageEnglish
Article number6218766
Pages (from-to)358-364
Number of pages7
JournalIEEE Transactions on Device and Materials Reliability
Volume14
Issue number1
DOIs
StatePublished - Mar 2014

Keywords

  • Blue light leakage
  • Ring-remote-phosphor structure
  • inverted-cone-lens encapsulant with gradient surface
  • phosphor-converted white light-emitting diodes (LEDs)

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