LED蓝光危害:检测合格即安全?

LED Blue Light Hazard: Is It Safe After Passing the Laboratory Test?

研究了大功率白色LED蓝光加权辐射亮度和单位光通量内蓝光加权辐射亮度随驱动电流、环境温度和点灯时间的变化规律。首先采用LED光色电综合分析仪测量同一批LED在不同驱动电流、不同环境温度和不同点灯时间时的光谱,然后计算相对蓝光加权辐射亮度Lb和单位光通量内的蓝光加权辐射亮度Lb/Ф,并得到Lb和Lb/Ф随点灯条件的变化关系,最后分析了他们变化的原因。研究表明:Lb随驱动电流的增加线性增大,随着温度的增加而线性减小,随着点灯时间增加呈指数形式减小,Lb变化主要原因是辐射功率变化.随着驱动电流的增加,LED光谱不断蓝移,导致Lb/Ф呈指数增加;随着环境温度的增加,虽然LED峰值波长红移,但是光谱逐渐加宽,因此,Lb/Ф变化较小;Lb/Ф还随着点灯时间的增加而不断增加,这主要是由于荧光粉性能不断退化,蓝光在光谱中的比例不断增加所致。因此,必须考虑LED灯具的实际点灯条件,才能达到健康照明的目的。

The change of blue light radiation and the rate of that with lumen of high power Light Emitting Diodes( LEDs) with drive current,ambient temperature and lighting time are analyzed. The spectral of the same LEDs with different current, ambient temperature and lighting time are measured with LED photoelectrical analyzer firstly,and then the relative blue light radiation( Lb) and the rate of that with lumen( Lb / Ф) are calculated,at last,the relationships between Lb,Lb / Ф and lighting conditions are obtained. It is shown that Lb,which mainly dependsed on the radiant power of LEDs,increases linearlyas the drive current increases. However,as the ambient temperature and lighting time increases,the blue light hazard decreases linearly and exponentially,respectively. Lb / Фincreases exponenaially as the drive current increases,due to the peak wavelength becomes shorter. Lb / Фchanges little when the ambient temperature increases from 20℃ to 70℃,because the peak wavelength and the full width at half maximum all increase. As the lighting time increases,the phosphor degrades,which results in the increase of the rate of blue light in LED spectrum,and then Lb / Ф increases. Therefore,the lighting conditions of LED should be considered for the healthy lighting.