Retroreflective Screen Microrecesses for High-Angle Efficiency
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Solution Overview
Problem
Existing image display systems on vehicle windshields face challenges with low retroreflection efficiency at high angles of incidence and complex manufacturing processes due to the need for accurately controlled oblique surfaces in retroreflective protrusions.
Innovation Solution
A method and mold design for creating a retroreflective screen with cube corner microrecesses having orthogonal lateral walls and a base, allowing for improved retroreflection efficiency across a wider range of angles and simplifying the manufacturing process by eliminating the need for precise control of oblique surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional retroreflective screens with cube corner protrusions are used, then retroreflection function is achieved, but manufacturing complexity increases due to the need for precisely controlled oblique surfaces
Solution Approach 1:
The patent inverts the conventional approach by creating microrecesses (cavities) instead of microprotrusions (projections). The cube corner structures are formed as recesses etched into the substrate surface, with their lateral walls being substantially orthogonal to the substrate plane rather than oblique. This inversion eliminates the need for precise oblique surface control while maintaining retroreflection functionality, as the orthogonal walls can be easily manufactured using standard vertical etching processes.
Solution Approach 2:
The patent changes the geometric parameters of the retroreflective structures from oblique lateral walls to substantially orthogonal lateral walls. This parameter change transforms the manufacturing requirements from needing precise angular control to needing only vertical wall formation, which is achievable through conventional etching methods. The orthogonal geometry maintains the cube corner configuration necessary for retroreflection while simplifying the manufacturing process.
2Reliability
If conventional retroreflective screens are used, then retroreflection is achieved, but retroreflection efficiency decreases at high angles of incidence
Solution Approach 1:
By inverting the structure from protrusions to recesses, the patent creates microrecesses that are more effective at high angles of incidence. The orthogonal lateral walls of these recesses provide better light return characteristics for oblique incident rays compared to conventional oblique surfaces, thereby improving retroreflection efficiency across a wider angular range including high angles.
Solution Approach 2:
The change in geometric parameters from oblique to orthogonal lateral walls modifies the light interaction characteristics of the retroreflective structures. The orthogonal configuration provides more consistent retroreflection performance across different incident angles, particularly improving efficiency at high angles where conventional oblique surfaces perform poorly.
3Ease of manufacture
If cube corner protrusions with oblique surfaces are manufactured, then retroreflection function is achieved, but device complexity increases
Solution Approach 1:
The patent simplifies the device structure by inverting the retroreflective elements from protrusions to recesses. The microrecesses with orthogonal lateral walls have a simpler geometric definition that can be directly formed by standard semiconductor etching processes, eliminating the need for complex multi-step shaping operations required to create precise oblique surfaces on protrusions.
Solution Approach 2:
The parameter change from oblique to orthogonal lateral walls reduces structural complexity by aligning the feature geometry with standard manufacturing process capabilities. The orthogonal walls require only vertical etching control rather than angular precision, simplifying both the device structure and its fabrication process.
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 70 degrees and reduces manufacturing complexity by using orthogonal surfaces in cube corner microrecesses, making the screen more suitable for vehicle windshields and other applications.
Implementation Method 1
The reflections on the lateral surfaces of the cube corners are based on the principle of total internal reflection
Implementation Method 2
forming micro-recesses from the rear surface of the first substrate by selective etching of the first substrate over said layer
Data Source
AI summary
A method of manufacturing a primary mold for the forming of a retroreflective screen, the method including the steps of: a) forming, on the front surface of such a substrate, a layer of a material such that the first substrate is selectively etchable over said layer; and b) forming microrecesses from the rear surface of the first substrate by selective etching of the first substrate over said layer, each microrecess emerging on the rear surface of said layer and having a back parallel to the front surface of the first substrate and first and second lateral walls orthogonal to each other and orthogonal to the back the first and second lateral walls and the back of the microrecess joining at a same point and forming a trihedron.