Adaptive Lighting Device for Snow Road Visibility
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Solution Overview
Problem
Existing lighting devices designed to address the Purkinje effect under mesopic vision conditions are ineffective when the road surface reflectivity changes, such as with snow cover, and emit bluish light, which does not improve vision effectively.
Innovation Solution
A lighting device comprising a first light source with a lower scotopic to photopic (S/P) ratio and a second light source with a higher S/P ratio, along with a controller that independently adjusts the light output of the second light source based on snow cover detection, ensuring optimal light emission under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lighting device emits bluish light with short wavelength components to address the Purkinje effect, then rod function is enhanced under mesopic vision, but vision improvement is insufficient when road surface reflectivity changes (e.g., snow cover)
Solution Approach 1:
The lighting device is segmented into multiple light sources with different spectral characteristics. Specifically, it includes a first light source (e.g., LED with peak wavelength 450-550 nm) that addresses the Purkinje effect by stimulating rod cells, and a second light source (e.g., LED with peak wavelength 560-650 nm) that provides photopic illumination. This segmentation allows independent control of each light source to adapt to different road surface conditions, resolving the contradiction between maintaining Purkinje effect effectiveness and adapting to varying reflectivity conditions.
Solution Approach 2:
The lighting device implements dynamic control by independently adjusting the intensity of each light source based on detected road surface conditions. The controller dynamically switches between or combines the first and second light sources depending on whether snow cover is present, enabling the system to adapt its spectral output to match the reflectivity characteristics of the road surface, thereby maintaining effective vision improvement across varying conditions.
2Reliability
If the lighting device uses a fixed spectral composition to address the Purkinje effect, then rod function is enhanced, but the device cannot adapt when snow cover changes road surface reflectivity
Solution Approach 1:
The lighting device is segmented into multiple light sources with different spectral characteristics. Specifically, it includes a first light source (e.g., LED with peak wavelength 450-550 nm) that addresses the Purkinje effect by stimulating rod cells, and a second light source (e.g., LED with peak wavelength 560-650 nm) that provides photopic illumination. This segmentation allows independent control of each light source to adapt to different road surface conditions, resolving the contradiction between maintaining Purkinje effect effectiveness and adapting to varying reflectivity conditions.
Solution Approach 2:
The lighting device implements dynamic control by independently adjusting the intensity of each light source based on detected road surface conditions. The controller dynamically switches between or combines the first and second light sources depending on whether snow cover is present, enabling the system to adapt its spectral output to match the reflectivity characteristics of the road surface, thereby maintaining effective vision improvement across varying conditions.
3Reliability
If the lighting device emits light optimized for mesopic vision with rods, then short wavelength components are increased, but perceived brightness and vision improvement deteriorate under snow covered conditions
Solution Approach 1:
The lighting device is segmented into multiple light sources with different spectral characteristics. Specifically, it includes a first light source (e.g., LED with peak wavelength 450-550 nm) that addresses the Purkinje effect by stimulating rod cells, and a second light source (e.g., LED with peak wavelength 560-650 nm) that provides photopic illumination. This segmentation allows independent control of each light source to adapt to different road surface conditions, resolving the contradiction between maintaining Purkinje effect effectiveness and adapting to varying reflectivity conditions.
Solution Approach 2:
The lighting device changes the spectral parameters of its light output by selectively activating different light sources. When snow cover is detected, the controller increases the intensity of the second light source (longer wavelength, photopic) while reducing or turning off the first light source (shorter wavelength, scotopic). This parameter change adapts the illumination to the high-reflectivity snow surface, improving perceived brightness while maintaining vision enhancement effectiveness.
Data Source
AI summary
A lighting device includes a first light source having a first S/P ratio, a second light source having a second S/P ratio that is higher than the first S/P ratio, and a controller configured to performing dimming control of light output from the first and second light sources. The controller performs the dimming control separately on the first and second light sources at least under a snow covered condition.