LED光衰色偏与伏安特性的关系

研究了大功率白色LED的伏安特性与光衰和色偏之间的关系。选择同一生产者、同一型号、光色性能较一致的大功率白色LED,在恒温环境下,进行350 mA恒流老炼实验;并用光色电综合分析仪测量初始、1周、2周和5周时的伏安曲线、光通量和色坐标。然后由初始时的伏安曲线计算LED的内阻和理想因子,并分析它们与光衰和色偏之间的关系。研究表明:老炼1周、2周和5周后的光衰与内阻、理想因子均正相关,但与理想因子的相关度大于内阻。老炼1周、2周和5周后的色偏与内阻的相关度大于0.8,与理想因子相关性较弱。因此,LED光衰可以用理想因子或内阻来表征,但理想因子优于内阻,而色偏只能用内阻来表征。

The relationship among luminous flux loss, color shift and voltage-current characteristics

The relationship between voltage-current characteristics and luminous flux loss or color shift of white light high power LEDs is investigated. LEDs with the same manufacture and type, and similar light output and color are selected to do aging experiment with the current of 350 mA and the constant ambient temperature. The voltage-current curve, luminous flux and color coordinates are measured with photometric, chromatic and electrical analyzer at the initial time, after 1,2 and 5 weeks, respectively. The internal resistance and ideal factor are obtained from initial voltage-current curve, and then the correlation between them and luminous flux loss or color shift is analyzed. It is found that luminous flux loss after 1,2 and 5 weeks aging is positive related with the internal resistance or ideal factor, and the ideal factor is more relevant than the internal resistance. The correlation coefficient between color shift and internal resistance is over 0.8, but ideal factor is not related to color shift. Therefore, the luminous flux loss can be evaluated with ideal factor or internal resistance, and the ideal factor is more suitable than internal resistance, the color shift can be assessed with ideal factor only.