| dc.description.abstract | This paper studies the LED light source used for night lighting to meet people′s ＂visual needs＂ -- high color rendering index and “non-visual effects ＂ - low circadian simulate values. In the first part, we design the LED light source and compare it with the existing fluorescent lamp. By adjusting the intensity of LED light source at different wavelengths, the blue light LED {Wp = 450nm} light source and the red LED {Wp = 630nm} light source mixed with green phosphor source {Wp = 540-545nm}, and white light with different color temperatures (2300 K-5000 K) can be obtained. The LED white light source has the characteristics of high color rendering index and has the advantage of lower circadian stimulation than the fluorescent lamp. This is because the LED source can choose a shorter blue LED peak wavelength radiation, thus ＂reducing the action spectrum effect acting on the human eye＂. In addition, because of the characteristics of the light source, the blue light spectral energy (<500 nm) of LED accounts for the total energy ratio, which is lower than that of the fluorescent lamp, and also effectively reduces the circadian simulate value.
The second part discusses the effects of LED lamp and fluorescent lamp on human melatonin. We analyzed the secretion of melatonin before and after exposure to different light sources. In the case of dim light (<10lux), there is an increase of 56%. In the case of LED (color temperature 3000 K), there is an increase of 46%. In the case of the fluorescent lamp (color temperature 3000 K, 5000K), it is only 25%, 15%. In this paper, we quantitatively studied the characteristics of light source. We can see that the inhibitory effect on melatonin secretion in the same {visual intensity} - ＂lumens＂, the inhibitory effect increased with {physiological brightness} - “circadian flux＂. And why the LED light source in this experiment can achieve good results. We concluded that LED 3000 K is lower in ＂circadian flux＂ and therefore weakened in the inhibition of melatonin secretion. And these data show that the spectral properties of LED can be finely tuned to reduce the non-visual effects on human beings.
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