LED光源光谱对隧道出口段明适应的影响

doi:10.3964/j.issn.1000-0593(2020)04-1044-07

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Abstract With the development of China’s economy, the development of highway tunnel construction is also rapidly. In the early stage of engineering design to ensure the safety of traffic in the tunnel, the power and location of the tunnel lighting sources all depend on the maximum outside luminance value and vehicle speed value through out the year. Although such a design considers safety, but it blindly increases the luminance of the tunnel illumination and it can not alleviate the problem of visual adaptation. However, with the application of LED in tunnels, the impact of LED sources spectra gradually attracted people’s attention. Moreover, the investigation found that the traffic accident rate of the highway tunnel in the exit section is relatively high. The main reason is that the luminance difference between the inside and outside of the tunnel is large, and the light adaptation time is long when the driver leavesthe tunnel exit. In order to study the impact of LED sources spectra on the light adaptation in tunnel exit, and to provide a basis for the selection of light source in tunnel exit, the LED source was characterized by a wide spectrum double-peak pattern. In the long wavelength range, the spectral content is different. The light adaptation is mainly related to two factors: the change of pupil area and photochemical reaction of the photopigment. LED light sources with different color temperatures have different spectral characteristics. The spectrum affects the time of light adaptation by affecting the synthesis of photopigment. The experiment selected 7 color temperature LED light sources used in the field of highway tunnel. The color temperatures are: 3 000, 3 500, 4 000, 4 500, 5 000, 5 700 and 6 500 K. Thirty observers were chosen for the experiment. All observers had normal visual corrected visual acuity. None of the observers had night blindness, color blindness or other diseases affecting night vision functions. The experiment was carried out in a simulated tunnel with a height of 2.8 m, length of 9 m and width of 5 m. Three photopic luminance levels for the experimental LEDs (4, 8 and 12 cd·m^-2), three illumination angles (15°, 20° and 25°) and two mounting heights (2.0, 2.4 m) were applied. In total, 126 lighting conditions were evaluated in the experiment. The results show that the higher luminance of the tunnel exit section, the shorter light adaptation times. When the luminance is the same, as the correlated color temperature increases, the light adaptation times decrease. The installation angle and height of the lamps have little effect on the sources spectra. Changing the installation height and angle can not effectively reduce the light adaptation time. This paper provides data and theoretical support for the selection of the color temperature in the exit section by analyzing the spectrum of LED sources with different color temperatures.

Key words：LED; Spectrum; Light adaptation mechanism; Light adaptation times; Exit section

Received: 2019-03-08 Accepted: 2019-07-19

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TN29

Corresponding Authors: QIN Ge E-mail: 18137297653@163.com

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2020)04-1044-07 OR https://www.gpxygpfx.com/EN/Y2020/V40/I04/1044