Distributed Light Projection via Variable Extraction Cells
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Solution Overview
Problem
Existing optical devices struggle with non-uniform light extraction across the surface of waveguides, leading to inconsistent image quality, and there is a need for variable light extraction coefficients along the guide to enhance image projection.
Innovation Solution
A distributed light projection device with multiple extraction cells along waveguides, each having different extraction coefficients, controlled by diffraction gratings with adjustable phase shifts to achieve a predefined intensity profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is extracted uniformly from all regions of the waveguide, then the device structure is simple, but the perceived image quality is poor due to non-uniform intensity distribution
Solution Approach 1:
The patent applies local quality by varying the extraction coefficient of each extraction cell according to its position along the waveguide. Extraction cells closer to the light source have lower extraction coefficients, while those farther away have higher coefficients. This localized adjustment of extraction properties compensates for the natural intensity decay along the waveguide, achieving uniform perceived image brightness across the display surface.
2Manufacturing precision
If extraction coefficients are varied along the waveguide to improve image quality, then uniform light distribution is achieved, but the device complexity increases
Solution Approach 1:
The patent implements parameter changes by adjusting the extraction coefficient parameter of each extraction cell based on its position along the waveguide. This involves modifying structural parameters such as grating depth, period, or orientation in each extraction cell to achieve the desired extraction profile. The systematic variation of these parameters along the waveguide enables precise control of light intensity distribution while maintaining manufacturing feasibility.
3Illumination intensity
If multiple extraction cells with different coefficients are used, then light intensity distribution is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the waveguide into multiple discrete extraction cell regions along its length. Each segment (extraction cell) is independently designed with specific extraction coefficients tailored to its position. This segmentation allows for localized optimization of light extraction while maintaining a modular structure that can be fabricated using standard waveguide manufacturing techniques, balancing performance requirements with manufacturing capabilities.
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
Enables precise control of light intensity distribution, improving image quality and uniformity across the projection surface.
Implementation Method 1
a light extraction device comprising, for each waveguide, a plurality of extraction cells, each extraction cell comprising two superimposed diffraction gratings
Implementation Method 2
N optical waveguides formed in or on a transparent substrate... each waveguide having a shape of a ribbon
Data Source
Figure 1
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AI summary
The present description relates to a distributed light projection device (100), comprising: - one or more waveguides (102i); and - above each waveguide, a plurality of extraction cells (104ij) coupled to distinct portions of the guide, each extraction cell comprising first (D1) and second (D2) superimposed diffraction gratings.