摘要
用于照明领域的白光LED,其出射光斑的色度均匀性对于产品性能有着更加重要的意义。介绍了目前工业上制作白光LED主要采用的荧光粉灌封点胶工艺。并在目前主流灌封点胶工艺的基础上通过改善荧光粉层结构形状,以提高白光LED器件的出射光斑均匀性。并通过九点法对不同工艺结构下LED出射光斑的空间色度分布进行了测量和分析。通过分析,虽然采用不同的粉层结构,能够一定程度上改善白光光斑的色度均匀性。但总体上,采用这种传统的点胶工艺制作的器件的白光光斑性能不好,现有的荧光粉层灌封点胶工艺存在很大的弊端。荧光粉层的可控性是影响色度均匀性(即光斑均匀性)的主要因素,包括单个器件内的光斑和器件之间的颜色一致性都不理想。
Combining phosphor with LED chip has become the most common method to realize white light output for white LED. Thermal conduction and phosphor coating are two key factors that influence on the quality of products. The spatial distributions of color temperature and chromaticity are the crucial parameters of power whiteLED used in lighting. The range of color temperature deviation within single white LED which can be distinguished by human eyes is from 50 K to 100 K. The uniformity of color temperature of white LED devices still cannot achieve the optimized standard, because the color temperature deviation of single product can even attain 800 K. This can be attributed on the nonuniformity of phosphor coating on the LED chip. Therefore, the uniformity of light output is of great importance as white LEDs found their way in the lighting application. The conventional dispensing method （or dipping method） for phosphor coating, which is much popular currently used in the LEDs industry, was introduced in this paper. Further, some modification had been made in the structure configuration of the phosphor layer to improve the uniformity of light output of white LEDs based on the dispensing process. Nine-point scheme had been adopted to measure the spatial distribution of brightness and chromaticity of light output of different LEDs samples with different process parameters. Although these modification has improved the uniformity of chromaticity of white light spot in a certain extent, as a whole the uniformity of white light output of devices made by employing conventional dispensing method of phosphor coating is still not good, and deviations of spatial coordinates of white light spots are larger than those of 0.01 that human eyes can distinguish. This can be ascribed to the cumber shape of phosphor coating. Since the process of phosphor coating is operated by handwork, the thickness of phosphor layer is not uniform which causes a big influence to the performance of products. In addition, the consistency of products o
出处
《发光学报》
EI
CAS
CSCD
北大核心
2008年第4期707-712,共6页
Chinese Journal of Luminescence
基金
十五国家科技攻关项目(2003ba316a01-02-02)
国家“863”计划(2006AA03A116)资助项目
关键词
白光LED
光斑均匀性
色度空间分布
white LEDs
uniformity of light spot
spatial distribution of chromaticity
