The Influence of Duty Ratio of PWM Modulation on Photometric and Colorimetric Quantity of Mixture of White LEDs
HU Yibin
LIU Shiwei
LIU Siyuan
LIU Tengfang
HU Le
ZHUAN Qiren
Abstract：Pulse width modulation ( PWM) is a common method for LED in intelligent lighting.In order to control photometric and colorimetric quantity of mixed light source of white LED accurately, this paper studies the photometric and colorimetric theoretical model of two channels ’ PWM based on mixed light source of the two kinds of white LED with different color temperatures, deducing the formula for chromaticity coordinate of mixed light source, correlated colour temperature, maximum luminance and ratio of duty ratio of two channels’ PWM.Two white LED samples of low color temperature (3282K) and high color temperature (12930K) were mixed in experiment, changing the duty ratio by controlling the pulse width.The results show that the experimental results are in fairly good agreement with the theoretical value, proving the correctness of the theoretical model.The results also show that we can ensure the luminous flux is higher than 70% of maximum in the range of 4233K to 7316K, when adjusting the chromaticity coordinate and correlated colour temperature of mixed light source by two channels’ PWM.
Keywords：white LEDchromaticityPWMduty ratio
Publication Date：2016-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 54-58 )