Retroreflecting Article with Contrast Reduction Layer for Sensor Calibration
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Solution Overview
Problem
Vehicle sensor systems face challenges in calibrating gain levels to detect both reflective and non-reflective objects simultaneously, particularly with traffic signs overwhelming the system due to high reflectivity, which affects accurate detection and interpretation of coded information.
Innovation Solution
A retroreflecting article with a contrast reduction layer positioned closer to the light incidence surface than the retroreflecting layer, which decreases near-infrared retroreflective efficiency by more than 50%, utilizing a combination of a retroreflecting layer and a retardation layer to manage light reflection and polarization, and optionally a visible absorbing layer to reduce visible light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a retroreflecting layer is used to increase visibility, then retroreflective efficiency is improved, but sensor system calibration difficulty increases due to overwhelming reflectivity
Solution Approach 1:
The retroreflecting layer is designed with spatially varying retroreflective efficiency across its surface. Regions with higher retroreflective efficiency are placed in areas where enhanced visibility is needed, while regions with lower efficiency are placed where sensor detection might be overwhelmed. This local variation allows the sign to maintain high overall visibility while providing calibrated regions that help sensor systems accurately detect and interpret coded information without being overwhelmed by excessive reflectivity.
2Illumination intensity
If high retroreflective efficiency is used for traffic signs, then visibility is improved, but object detection accuracy deteriorates due to overglow
Solution Approach 1:
The sign incorporates both high retroreflective efficiency regions for visibility and lower efficiency regions for accurate sensor detection. The patterned arrangement of these regions with different retroreflective properties allows the sign to simultaneously achieve high overall visibility while providing detectable patterns that sensor systems can accurately interpret without overglow interference.
Solution Approach 2:
The retroreflecting layer is segmented into multiple regions with different retroreflective efficiencies. This segmentation creates distinct high-visibility areas and coded information areas with controlled reflectivity, allowing sensor systems to differentiate between the sign's presence (detected via high reflectivity regions) and the coded information (detected via patterns in lower reflectivity regions), thereby improving detection accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables vehicles to accurately detect and interpret reflective and non-reflective objects by reducing overglow and improving detection fidelity, allowing for better navigation and object recognition without overwhelming sensor systems.
Implementation Method 1
Retroreflecting elements reflect incident light back in substantially the same direction. Retroreflecting elements include cube-corner prismatic retroreflectors and beaded retroreflectors.
Implementation Method 2
The contrast reduction layer decreases the near-infrared retroreflective efficiency of the retroreflecting substrate by more than 50%.
Implementation Method 3
utilizing a combination of a retroreflecting layer and a retardation layer to manage light reflection and polarization
Data Source
AI summary
Retroreflecting articles are described. In particular, retroreflecting articles including retroreflecting layers and contrast reduction layers are described. The contrast reduction layer decreases the near infrared retroreflective efficiency of the retroreflecting substrate by more than 50%.