Transparent Projection Screen Surface Relief Scattering
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Solution Overview
Problem
Existing transparent projection screens face limitations in providing clear projection and see-through views due to inherent scattering properties, leading to performance degradation, inflexible design constraints, or high production costs, particularly in achieving desired scattering profiles.
Innovation Solution
A transparent screen design featuring a first transparent substrate with a surface relief pattern and a partially reflective coating, bonded with a second transparent substrate using an optical adhesive, allowing for a random scattering surface that eliminates minimum pixel size limitations and enables space-variant scattering profiles without the need for complex lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a scattering surface is used for projection, then the projected image can be viewed, but the transparency and clarity of the see-through view deteriorates
Solution Approach 1:
The scattering function is segmented from the substrate and implemented through a separate surface relief pattern layer. This allows the substrate to remain transparent while the surface relief pattern provides the necessary scattering function for projection, resolving the contradiction between projection reliability and view clarity.
Solution Approach 2:
The surface relief pattern is applied locally to specific regions of the substrate where projection is needed, while other regions maintain full transparency. This localized approach allows different parts of the screen to have different optical properties, enabling both projection and clear viewing simultaneously.
2Object-generated harmful factors
If pixel-sized beam expanders are used as scattering elements, then laser speckle is minimized, but display resolution is limited by the minimum pixel size requirement
Solution Approach 1:
The beam expander function is extracted from the pixel structure and implemented through a continuous surface relief pattern. This eliminates the need for discrete pixel-sized elements, allowing display resolution to be limited only by the projection system rather than by the scattering element size, while still maintaining laser speckle minimization.
Solution Approach 2:
The scattering function transitions from a two-dimensional array of discrete elements to a continuous surface relief pattern with varying height. This dimensional change allows the scattering profile to be controlled through surface topology rather than through discrete element spacing, enabling higher resolution displays.
3Reliability
If off-normal scattering symmetry is achieved using replicated fundamental elements, then the scattering profile is optimized, but manufacturing complexity and cost increase due to grayscale lithography requirements
Solution Approach 1:
Instead of using complex grayscale lithography to create unique profiles at each point, the invention uses a single master surface relief pattern that can be replicated or tiled across the screen. This copying approach maintains the desired off-normal scattering symmetry while dramatically simplifying manufacturing.
Solution Approach 2:
A single surface relief pattern design serves multiple functions: it provides the off-normal scattering symmetry needed for optimized projection, and it can be replicated across the entire screen area. This universal design eliminates the need for complex point-by-point lithography while maintaining scattering profile performance.
4Object-affected harmful factors
If minimal scattering is introduced for transparency, then the see-through view is clear, but the projection function becomes very dim
Solution Approach 1:
The surface relief pattern uses curved, spheroidal scattering elements that efficiently redirect projected light toward the viewer while maintaining overall transparency. The curved geometry provides controlled scattering that enhances projection brightness without significantly degrading the see-through view, resolving the contradiction between the two functions.
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 design achieves clear projection and see-through views without pixel size constraints, improving display efficiency and reducing production costs by using a random scattering surface and optical adhesive matching, allowing for various scattering profiles and applications such as augmented reality.
Implementation Method 1
a first transparent substrate having a first transparent substrate index of refraction and including a surface relief pattern
Implementation Method 2
a partially reflective coating formed on the surface relief pattern
Implementation Method 3
an optical adhesive having the first transparent substrate index of refraction
Data Source
AI summary
According to some embodiments, a transparent screen includes a first transparent substrate having a first transparent substrate index of refraction and including a surface relief pattern, a partially reflective coating formed on the surface relief pattern, and a second transparent substrate bonded over the partially reflective coating with an optical adhesive having the first transparent substrate index of refraction.