Phosphor-converted white LED with low deviation of correlated color temperature and color coordinates and method of preparing the same

Patent metadata

Field	Value
Publication number	US-9078331-B2
Application number	US-201313903190-A
Country	US
Kind code	B2
Filing date	May 28, 2013
Priority date	Sep 15, 2011
Publication date	Jul 7, 2015
Grant date	Jul 7, 2015

Abstract

A light emitting device is provided to produce white light with a stable correlated color temperature and stable color coordinates. The light emitting device includes a blue LED chip and a yellow phosphor. The blue LED chip has a peak wavelength X slightly smaller than the peak wavelength Y of the phosphor such that when the light emitting device is subjected to a predetermined operating current, the phosphor decays due to thermal effect, and the LED chip has its emission spectrum red-shifted to substantially match with the excitation spectrum of the phosphor. At this time, the excitation ability of the LED chip is increased and causes an increase of yellow power output from the phosphor that substantially compensates a decrease of yellow light output caused by the phosphor.

First claim

What is claimed is:

1. A method of preparing a light emitting device that produces white light with a stable correlated color temperature (CCT) and stable color coordinates, the method comprising the steps of:
providing a blue LED chip and a yellow phosphor with a specific concentration for converting part of blue light emitted from the LED chip to yellow; wherein the LED chip has an initial emission spectrum with a peak wavelength X slightly smaller than a peak wavelength Y of an…

Assignees

• Univ Nat Central

Inventors

• Sun Ching-Cherng
• Chen Ching-Yi
• Wu Hsin-Mei
• Chen Cheng-Chien

Classifications

• C09K11/7774

  Chemistry & Metallurgy · mapped topic

• H10H20/0361

  Electricity · mapped topic

• H10H20/8512 Primary

  Electricity · mapped topic

• H05B33/10

  Electricity · mapped topic

• H05B33/14 Primary

  Electricity · mapped topic