White illumination characteristics of ZnS-based phosphor materials excited by InGaN-based Ultraviolet Light-Emitting Diode

被引:20
作者
Murakami, K [1 ]
Taguchi, T [1 ]
Yoshino, M [1 ]
机构
[1] Yamaguchi Univ, Fac Engn, Dept Elect & Elect Engn, Yamaguchi 7558611, Japan
来源
DISPLAY TECHNOLOGIES III | 2000年 / 4079卷
关键词
InxGa1-xN-based UV LED; ZnS-based white phosphor; chromaticity; general color rendering index; reflection brightness; white LED;
D O I
10.1117/12.389396
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
White illumination characteristics of ZnS-based phosphor materials exited by an InxGa1-xN-based single quantum well (SQW) -structure ultraviolet (UV) light-emitting diode (LED) have extensively been investigated. In order to evaluate white luminescence, two kinds of ZnS-based white phosphors have been employed. When an UV LED was operated at a current of 10 mA, chromaticity (x, y), color temperature (Tc) and general color rendering index (Ra) of the white luminescence are obtained to be (x, y)=(0.29, 0.33), Tc=7700 K and Ra=70, respectively, for ZnS:Ag + (Zn,Cd)S:Cu,Al phosphors, whilst (x, y)=(0.31: 0.34). Tc=6900 K and Ra=83, respectively, for white phosphor material including ZnS:Cu,Al, Sr and Y materials. The value of chromaticity slightly changed with increasing forward current of the UV light source. As a result, it is possible to obtain stable white luminescence spectrum. The dependence of the luminescence brightness on the thickness of phosphor shows a tendency to saturate for reflection brightness, but for transmission brightness its dependence has a peak due to light scattering effect. The reflection brightness was higher than the transmission brightness. It is revealed that the white luminescence light of stable chromaticity and high brightness using reflection light can be obtained.
引用
收藏
页码:112 / 119
页数:8
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