Waveguide Partial Reflection Surfaces for Uniform AR Display Brightness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing waveguide substrates suffer from non-uniform brightness and color when displaying video images, leading to impaired realism in augmented reality applications, and require complex manufacturing steps and increased costs due to varying reflectance of partial reflection surfaces.
Innovation Solution
A waveguide design with parallel first and second internal reflection surfaces and a plurality of partial reflection surfaces, where the intensity of output light reflected by each partial reflection surface is greater than or equal to the intensity of the adjacent surface, ensuring uniform brightness and color across different angles of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the reflectance of partial reflection surfaces is changed to secure uniformity of brightness of video image, then uniformity of brightness is improved, but uniformity of color of outside world is impaired and manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by positioning multiple partial reflection surfaces at specific locations within the waveguide, where each surface has the same reflectance but different spatial positions. This arrangement ensures that light is reflected at multiple points along the propagation path, achieving uniform brightness distribution across the video image without requiring different reflectance values for different surfaces, thereby simplifying manufacturing while maintaining image quality.
2Reliability
If the reflectance of each partial reflection surface is set to be greatly different depending on incident angle to prevent ghost video image, then ghost image is prevented, but uniformity of color of outside world is impaired
Solution Approach 1:
The patent changes the parameter of reflectance from being angle-dependent to being angle-independent. By designing partial reflection surfaces with constant reflectance values regardless of incident angle, the system prevents ghost images through proper surface positioning and arrangement rather than through angle-dependent reflectance modulation, thereby maintaining color uniformity of the outside world while achieving ghost image prevention.
3Illumination intensity
If multiple partial reflection surfaces are added to achieve uniform brightness, then brightness uniformity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent uses local quality by placing multiple partial reflection surfaces at specifically designed positions within the waveguide. Each surface has identical reflectance properties, but their different locations create the desired uniform brightness effect. This approach achieves the brightness uniformity goal while keeping manufacturing relatively simple, as all surfaces can be manufactured with the same reflectance specification rather than requiring complex variable reflectance coatings.
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
This design achieves uniform brightness and color both for the video image and the outside world, reducing the sense of discomfort and manufacturing complexity while maintaining high realism in augmented reality displays.
Implementation Method 1
first and second internal reflection surfaces that propagate the video image light incident from the incident surface while totally reflecting the video image light
Implementation Method 2
a plurality N of partial reflection surfaces that reflect a part of the video image light propagating by being totally reflected by the first and second internal reflection surfaces
Data Source
AI summary
Both uniformity of brightness and uniformity of color of the outside world are seen via a waveguide. A video image is reflected by a partial reflection surface inside the waveguide that includes an incident surface on which video image light is incident, first and second internal reflection surfaces that propagate the video image light incident from the incident surface while totally reflecting the video image light, and are substantially parallel to each other. A plurality of partial reflection surfaces that reflect a part of the video image light propagating by being totally reflected by the first and second internal reflection surfaces, output the part of the video image light as output light from the first internal reflection surface to the outside of the waveguide, and transmit the part of the video image light being incident, and are disposed substantially parallel to each other inside the waveguide.