Color-Compensated Waveguide Optics for Near-Eye Displays
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Solution Overview
Problem
Existing near-eye displays face challenges in achieving improved form factor, manufacturability, intensity, achromaticity, and image uniformity due to complex waveguide geometries and facet coatings, making it difficult to design and manufacture coatings that meet consumer demands for smaller form factors and better image quality.
Innovation Solution
The use of a non-white balanced light source and complementary white normalized partially reflective facet coatings, along with light sources that emit light to compensate for the chromatic reflectance of the facets, allows for better manufacturability and efficient light throughput, resulting in a smaller overall form factor and improved image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If white-balanced light sources and achromatic facet coatings are used, then image color accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies color changes by using chromatic facet coatings that reflect specific wavelengths and complementary colored light sources. The facet coatings are designed with chromatic reflectance properties (e.g., reflecting red light while transmitting other wavelengths), and the light source emits complementary colors (e.g., cyan light) to compensate for the coating's chromatic effects. This approach transforms the traditional requirement for achromatic coatings into a system that intentionally uses and compensates for chromatic properties, simplifying manufacturing while maintaining color accuracy.
Solution Approach 2:
The patent changes the parameters of the light source from traditional white-balanced to non-white-balanced with specific spectral characteristics. The light source is configured to emit light with a spectrum that compensates for the chromatic reflectance of the facet coatings. By adjusting the spectral parameters of the light source and the chromatic properties of the coatings, the system achieves simplified manufacturing requirements while maintaining image quality.
2Ease of manufacture
If chromatic facet coatings are used, then manufacturability is improved, but light color uniformity deteriorates
Solution Approach 1:
The patent converts the harmful chromatic effect of the facet coatings into a beneficial property. Instead of treating chromatic reflectance as a defect to be eliminated, the system deliberately uses chromatic coatings and pairs them with complementary colored light sources. The chromatic reflectance that would normally cause color non-uniformity is transformed into a controllable parameter that simplifies manufacturing while the complementary light source compensates for any remaining color effects, turning a potential harm into a benefit.
Solution Approach 2:
The patent implements a feedback mechanism where the spectral characteristics of the light source are specifically designed to compensate for the chromatic reflectance of the facet coatings. The light source parameters are adjusted based on the known chromatic properties of the coatings, creating a feedback loop that ensures color uniformity in the final image while allowing the use of simpler chromatic coatings during manufacturing.
3Productivity
If traditional white light sources are used, then color accuracy is maintained, but light throughput efficiency decreases
Solution Approach 1:
The patent applies local quality by optimizing the spectral distribution of the light source to match the specific requirements of the chromatic facet coatings at different locations and angles within the waveguide. Rather than using a uniform white light spectrum, the light source is configured with a non-uniform spectral profile that provides enhanced throughput efficiency for the wavelengths that need to be reflected by the chromatic coatings, while maintaining color accuracy through the complementary color compensation mechanism.
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 approach enhances manufacturability and efficiency while maintaining image uniformity and intensity, addressing the challenges of complex waveguide geometries and coatings in near-eye displays.
Implementation Method 1
one or more light input coupling elements configured to couple incident light into the light-transmitting substrate thereby trapping the light between the first and second major surfaces by total internal reflection
Implementation Method 2
one or more light reflecting elements configured to couple the light out of the substrate, the one or more light reflecting elements having chromatic reflectance for coupling the light further down the substrate or out of the substrate
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
A method for generating an image in a near-eye display may include operating a light source to emit the image as incident light. The light source may be configured such that incident light as received by the light reflecting elements compensates for the chromatic reflectance of the light reflecting elements. The method may include coupling the incident light into a light-transmitting substrate, thereby trapping the light between first and second major surfaces of the light-transmitting substrate by total internal reflection and coupling the light out of the substrate by the light reflecting elements having chromatic reflectance.