The Impact Of LED Light Color On The Dark Adaptation Of Human Vision In Tunnel Entrances

The research of this paper is based on the project of National Natural Science Foundation of China,"the applicability of LED Light Source Spectrum/Color temperature to Tunnel Lighting".When drivers go from bright environment to dark environment,There will be"black hole effect" and temporary blindness,which will seriously affect the driving safety,especially the frequent traffic accidents at the entrance section of the tunnel.Therefore,it is necessary to study the dark adaptation of the tunnel entrance section.The intuitive feeling of lighting is luminance and color.The occurrence of dark adaptation is mainly related to two factors,one is the change of the brightness of the light source before and after the dark adaptation,and the other is the change of the light color of the light source.Due to the limitation of traditional light sources such as high-pressure sodium lamps,in order to reduce the influence of dark adaptation of the tunnel entrance section,the uniformity of brightness and brightness has become the main factor considered in the design and application of tunnel illumination.Most studies on dark adaptation are also carried out from the perspective of brightness.However,with the advent of high-power white LEDs,the light color characteristics of the light source can no longer be ignored,and the illumination brightness of the tunnel entrance section is between 40 cd/m2 and 140 cd/m2,which belongs to the bright visual range,mainly cone-shaped.The cell works,it is used to distinguish the color,so this paper studies the dark adaptation of the tunnel entrance section from the perspective of the light source color.The spectrum of the light source determines the light color characteristics of the light source.The smaller the difference between the spectrum of the illumination source of the tunnel entrance section and the spectrum of the sunlight outside the tunnel,the better the visual effect of the human eye,and the better it is to reduce the influence of dark adaptation;The dark adaptation indicator is able to identify the target and the background.The higher the color rendering of the light source,the target and the higher the background contrast,the shorter the dark adaptation time.Combining theoretical analysis and experiment,this paper analyzes the difference between solar light and 7 color temperature LED spectra,and the color rendering of 7 color temperature LEDs.Based on dark adaptation time,it is 2.8 meters high,9 meters long and 5 wide.In the simulated tunnel of meters,three inlet segments were selected for brightness,three mounting angles,two mounting heights,and 60 observers were tested.The experimental results show that the light color of the light source has a significant influence on the dark adaptation of the inlet section.The closer the LED spectrum is to the sunlight,the better the color rendering is,and the shorter the dark adaptation time is.Among the 7 color temperature LEDs,4500K has the best light color characteristics.Therefore,it is recommended that in the tunnel lighting design and application,the inlet section lighting selects the LED of about 4500K color temperature.