Transparent IR Retroreflective Articles for Autonomous Vehicle Detection
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Solution Overview
Problem
Autonomous vehicles face difficulty in distinguishing dark-colored objects using infrared (IR) sensors due to low reflectivity, leading to challenges in object detection, as conventional retroreflective materials are either not visible to IR sensors or overly visible to the human eye.
Innovation Solution
A retroreflective article with a structured surface and a pressure-sensitive adhesive forming optically inactive areas, combined with a low refractive index layer to create optically active areas that retroreflect IR radiation without visible retroreflection, allowing for controlled signal return to IR sensors while maintaining a clear appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retroreflective materials are used to improve IR detectability, then IR sensor detection is improved, but visual appearance is altered (overly visible to human eye)
Solution Approach 1:
The retroreflective layer is segmented into multiple discrete optically active areas that retroreflect IR radiation, separated by optically inactive areas that do not retroreflect. This segmentation allows the article to provide sufficient IR signal return while maintaining a visually subdued appearance, as the optically active areas occupy only a portion of the total surface area.
Solution Approach 2:
Different regions of the retroreflective article are given different optical properties: optically active areas with retroreflective properties for IR detection, and optically inactive areas that are visually transparent or non-retroreflecting. This local differentiation enables the article to satisfy both IR detectability requirements and visual appearance requirements simultaneously.
2Reliability
If retroreflective coverage is increased to provide stronger signal to IR sensors, then detection reliability is improved, but visual overwhelming increases
Solution Approach 1:
Instead of making the entire surface optically active, the invention uses partial action by limiting optically active areas to specific portions of the retroreflective layer. This provides sufficient IR signal return for reliable detection while avoiding excessive visual retroreflection that would be overwhelming to human observers.
3Illumination intensity
If dark colors are used on vehicle surfaces, then visual appearance is improved, but IR sensor detection is worsened
Solution Approach 1:
The retroreflective article with optically active areas can be applied to dark-colored vehicle surfaces without altering the overall dark visual appearance, while locally providing IR retroreflection at the optically active areas. This allows dark colors to maintain their visual aesthetic benefits while the optically active areas compensate for the poor IR reflectivity of dark surfaces.
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 the detection of dark-colored objects by IR sensors without altering the visual appearance, providing an appropriate signal strength to IR machine vision systems while minimizing visual retroreflection.
Implementation Method 1
a retroreflective layer including a structured surface that is opposite a major surface
Implementation Method 2
at least one low refractive index layer forming an optically active area that retroreflects incident light
Implementation Method 3
a pressure sensitive adhesive that contacts at least a portion of the structured surface to form an optically inactive area that does not substantially retroreflect incident light
Data Source
AI summary
A retroreflective article including a retroreflective layer including a structured surface that is opposite a major surface, a pressure sensitive adhesive that contacts at least a portion of the structured surface to form an optically inactive area that does not substantially retroreflect incident light and at least one low refractive index layer forming an optically active area that retroreflects incident light, wherein the optically active area comprises about 25% or less of the structured surface.