Retroreflective Screen Microprotrusions for High-Angle Efficiency
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Solution Overview
Problem
Existing systems for displaying images on vehicle windshields face inefficiencies in retroreflection at high angles of incidence and have complex manufacturing processes due to precise angle requirements of oblique faces in retroreflecting protuberances.
Innovation Solution
A retroreflective screen with microprotuberances forming trihedrons, where the first, second, and third faces are coated with reflective metallization, and the microprotuberances are distributed with less than 50% coverage, manufactured using a mold with etched microrecesses and trenches to simplify production and improve retroreflection efficiency across a wider range of angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oblique faces are used in retroreflective protuberances to achieve retroreflection, then retroreflection function is improved, but manufacturing precision requirements increase due to precise angle control needs
Solution Approach 1:
Instead of forming retroreflective protuberances with oblique faces that require precise angle control, the patent inverts the approach by using microprotrusions with substantially vertical faces. The retroreflection is achieved through total internal reflection at these vertical faces, eliminating the need for precise angle control while maintaining the retroreflection function.
Solution Approach 2:
The patent changes the geometric parameters of the retroreflective structures from oblique faces with specific angles to substantially vertical faces. This parameter change simplifies manufacturing by removing the requirement for precise angle control while still achieving effective retroreflection through total internal reflection.
2Reliability
If retroreflective protuberances with oblique faces are used, then retroreflection is achieved, but device complexity increases due to manufacturing process complexity
Solution Approach 1:
The patent simplifies the manufacturing process by inverting the traditional retroreflective structure. Instead of complex oblique faces requiring precise angular control, the invention uses simple substantially vertical microprotrusions that can be manufactured with standard molding techniques, significantly reducing device complexity.
3Ease of manufacture
If microprotrusions with vertical faces are used, then manufacturing is simplified, but retroreflection efficiency at high angles may be reduced
Solution Approach 1:
The patent changes the face orientation parameter from oblique to substantially vertical, which simplifies manufacturing. This parameter change is compensated by utilizing total internal reflection physics, which maintains retroreflection efficiency even at high angles of incidence up to 80 degrees.
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
The solution enhances retroreflection efficiency for angles up to 80 degrees, simplifies manufacturing by eliminating the need for precise angle control of oblique faces, and maintains transparency for outdoor scene viewing.
Implementation Method 1
The reflections on the lateral faces of the cube corners are based on the principle of total internal reflection
Implementation Method 2
Alternatively, the lateral faces of the cube corners can be covered with a material that reflects the side of face 201b of the screen. The reflections on the lateral faces of the cube corners are then mirror reflections
Data Source
Figure 1~2
Figure 3A~5B
Figure 6A~8B
AI summary
The invention relates to a retroreflective screen comprising a first film (351) of a transparent material, one face of which comprises a plurality of microprotrusions, each microprotrusion having a first face substantially parallel to the mean plane of the screen, and second and third faces substantially orthogonal to each other and substantially orthogonal to the first face, the first, second and third faces of the microprotrusion meeting at the same point and forming a trihedron.