基于峰值电流可调的PWM调光方法减小LED漂移  

Reducing color shift of LED by PWM dimming mode with adjustable peak current

作　　者：宋鹏程[1] 文尚胜[1,2] 关伟鹏 陈颖聪[1] 

机构地区：[1]华南理工大学高分子光电材料与器件研究所,广东广州510640 [2]华南理工大学发光材料与器件国家重点实验室,广东广州510640

出　　处：《光电子．激光》2015年第10期1895-1901,共7页Journal of Optoelectronics·Laser

基　　金：广东省战略性新兴产业专项(2011A081301017;2012A08034012;2012A080304001);广州市科技计划(2013J4300021)资助项目

摘　　要：荧光粉和发光二极管(LED)芯片的发光性质受电流和结温影响,其变化使白光LED调光时产生色漂移。通过对白光LED在线性调光和脉冲宽度调制(PWM)调光下色度学参数的测试分析发现,PWM调光具有更优异的色稳定性;温度升高导致荧光粉转换效率降低;峰值电流增大致使蓝光与荧光粉的匹配程度降低。为了进一步降低PWM调光过程中的色漂移,采用峰值电流可调的PWM调光方案,当相关色温CCT大于设定值时,可通过降低峰值电流增加占空比的方法降低CCT,反之则通过增加峰值电流降低占空比的方法增加CCT。实验结果表明,通过调整峰值电流可补偿因荧光粉转换效率变化造成的色漂移,在预设调光范围内的CCT变化小于33 K。对目标CCT与色稳定范围的关系进行了探讨。The luminescent properties of the phosphors and LED chips are directly affected by the work- ing current and junction temperature. This influence may lead to color shift during dimming process of the white-light LED. In order to investigate the color-shift mechanism of white-light LED, colorimetric parameters of the LED are measured at linear and pulse width modulated （PWM） diming modes. It is found that PWM dimming offers better color stability;A raising temperature reduces the phosphor con- version efficiency^The matching degree between the blue light and phosphor is disturbed by the raising peak current. To minimize the color shift over dimming,a new PWM dimming mode with adjustable peak current is proposed. When the correlated color temperature is higher than the set value, it can be reduced by reducing the peak current and extending the duty cycle. Conversely, by increasing the peak current and shortening the duty cycle, the correlated color temperature can be increased when it is too low. It is shown experimentally that by using this dimming mode, the color shift caused by the change of phosphor conversion efficiency can be successfully compensated at PWM dimming with adjustable peak current, leading to a color temperature change of less than 33 K in the dimming range. Finally, the relationship between the target correlated color temperature and the color stability range is discussed.

关 键 词：发光二极管(LED) 色漂移 脉冲宽度调制(PWM) 线性调光 荧光粉 

分 类 号：TN312[电子电信—物理电子学]