Research on LED Road Lighting Effect Based on Visual Efficacy Method and Pedestrian Walking Song Jiayin Ma Jian Liu Gang (Tianjin University Tianjin Building Physical Environment and Ecological Technology Focus. Observers test at the end of the road model through observation holes of different viewing angles, The reaction time from the movement to the discovery of the obstacle was recorded in different road brightness environments.
Reaction time of four kinds of light sources under three contrasts Road surface brightness (cd/m2) Visual standard contrast C light source High pressure sodium lamp C1=0.5 When road surface brightness and reaction time relationship C2=0.4 When road surface brightness and reaction time relationship C3=0.3 The relationship between brightness and reaction time can be seen from Table 1 under three contrasts. Table 2 The fitting function of the reaction time and the road surface brightness x under three kinds of contrasts Contrast function relationship Formulation coefficient High-pressure sodium lamp 4 The influence of the source spectrum on the reaction time The test results of the four kinds of light source characteristics and the previous reaction time test results A comparative study was conducted to obtain a mechanism that affects the reaction time. The spectra of the four sources were tested as shown.
The main parameters of the test results of the light source were extracted, and the table 3 was obtained. The reaction time according to the main parameters and the contrast ratio of 0.4 was carried out by comparison.
4 kinds of light source spectrum table 3 reaction time and 4 kinds of light source parameters contrast high pressure sodium lamp road surface brightness is 0.001 cd / m2 reaction time (ms) road surface brightness is 0.1 cd / m2 reaction time (ms) road surface brightness is 3.2 cd / m2 Reaction time (ms) Color temperature (K) Color rendering 450nm Wavelength Relative spectrum 540nm Wavelength Relative spectrum 610nm Wavelength Relative spectrum 500nm Wavelength Relative spectrum 580nm Wavelength Relative spectrum 4.1 Color temperature Effect on reaction time It can be seen from the data in Table 3 that although high pressure sodium lamp and LED1 The color temperature difference is small, but the reaction time between them in the low road surface brightness (0.001 cd/m2) environment is very different, while the brightness of the road surface between LED1 and LED2 and between LED2 and LED3 is 0.001 cd/m2. The difference in reaction time is far less than the difference in color temperature. All four light sources have a tendency to decrease as the reaction time increases with color temperature, but the relationship between color temperature and reaction time is not a rigorous linear function. Therefore, it can be inferred that the difference in reaction time between the high-pressure sodium lamp and the LED lamp is not only caused by the difference in color temperature, but other factors may affect the visual effect of the subject. 4.2 The effect of color rendering on the reaction time It can be seen from Table 3 that the color rendering of the high pressure sodium lamp is only 20%, and the color temperature of the similar color LED1 can reach 73%. With the significant increase in color rendering, It can be seen that the reaction time LED1 at the low road surface brightness level (0.001 cd/m2) is 114.4 ms lower than that of the high pressure sodium lamp, and at the medium and high road surface brightness level (0.1 cd/m2) and the high road surface brightness level (3.). The reaction time is slightly smaller than that of the high pressure sodium lamp. The color rendering of the three types of LED lamps is not much different. The minimum LED1 differs from the largest LED3 by only 3. 5%. The response time of the three LED lamps is not large under the low, medium and high road surface brightness levels. The difference between the LED1 and LED2 reaction time is 48. 98ms, and the reaction time is almost the same at the medium and high road surface brightness levels, even in the low road surface brightness (O.OOlcd/m2). The reaction time of LED2 is much smaller than that of LED3 under high road surface brightness level. The law of time is consistent with the difference of color rendering of four kinds of light sources, and the relationship between color rendering of visible light source and reaction time is more closely, and this law It is more suitable in the environment with low road surface brightness, but in the environment of medium and high road surface brightness, although this law still exists, the law is weakened as the road surface brightness increases.
4.3 Influence of source spectrum on reaction time It can be found from Table 3 that the relative spectrum of high-pressure sodium lamps at the wavelengths of 450 nm and 540 nm which have a positive influence on the color rendering of the light source is missing, that is, the components lacking blue and green wavelength light in the high-pressure sodium lamp. It is the main reason why the reaction time of LED1 is much lower than that of high pressure sodium lamp at low brightness level (0.001 cd/m2). As the road surface brightness level increases, the energy of the 450 nm and 540 nm wavelengths is less affected by the reaction time.
The larger the energy value of the growth point, the shorter the reaction time, and the larger the energy value at the wavelength of 580 nm, the longer the reaction time. This rule is very prominent at low road surface brightness levels (0.001 cd/m2), and with the increase in road surface brightness, the mid-road brightness level (0.1 cd/m2) and the high road surface brightness level (3.2 cd/m2). The trend is decreasing.
5 Conclusions By analyzing the test data of reaction time, it can be obtained that the reaction time of LED is less than that of high-pressure sodium lamp in the range of 0.001~3.2cd/m2 road surface brightness. It can be seen that the visual efficiency of LED lamp is obviously higher than that of high pressure sodium lamp. Further, as the contrast becomes larger, the reaction time of the four kinds of light sources as a whole is lowered.
The software analyzes the relationship between reaction time and road surface brightness, and obtains a functional relationship between reaction time y and road surface brightness x under different contrasts, and the fitting relationship is very good.
According to the comparison between the spectral characteristics of the four kinds of light sources and the reaction time, it is found that the effect of color rendering on the reaction time is more closely related to the color temperature. The 450nm and 540nm wavelength energy, which have a major influence on the color rendering of the light source, also have a positive effect on the reaction time, while the 580 nm wavelength energy has a negative influence on the reaction time, but these effects decrease as the road surface brightness level increases.
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