Waveguide Display with Multi-Facet Light Extraction
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Solution Overview
Problem
Optical waveguide-based displays suffer from optical crosstalk, low light efficiency, and poor contrast at high ambient light levels due to inherent design limitations, including slow response times and inefficient light modulation.
Innovation Solution
A display design featuring an optical waveguide with a light source and tilting micro-mirrors or micro-prisms that modulate light by total internal reflections, using light-absorbing coatings and prism films to absorb ambient light and improve viewing angles, allowing simultaneous image display with high contrast and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If picture elements are activated sequentially to eliminate optical crosstalk, then optical crosstalk is reduced, but light efficiency decreases significantly
Solution Approach 1:
The waveguide surface is segmented into multiple facets (first facet at 45 degrees, second facet at 15 degrees, third facet at 75 degrees) that spatially separate the optical paths of adjacent picture elements. This segmentation prevents light from one picture element from reaching adjacent elements, eliminating crosstalk without requiring sequential activation.
Solution Approach 2:
The invention introduces a dimensional solution by using multi-facet structures that redirect light in different spatial directions. Instead of temporal separation (sequential activation), the patent uses spatial separation through angled facets to direct light from each picture element to its designated viewing area while blocking light from adjacent elements.
2Ease of operation
If mirror surfaces are used to redirect light to the viewer, then light direction control is improved, but contrast ratio deteriorates due to ambient light reflection
Solution Approach 1:
Different facets of the waveguide structure are assigned different functions: the first facet (45 degrees) redirects display light to the viewer, the second facet (15 degrees) absorbs ambient light, and the third facet (75 degrees) provides additional light extraction. This local differentiation of functions allows simultaneous achievement of good light direction control and ambient light rejection.
Solution Approach 2:
The invention converts the harmful effect of ambient light into a beneficial function by using the second facet specifically designed to absorb and eliminate ambient light reflections, thereby improving contrast ratio while maintaining the mirror surface's ability to redirect display light.
3Manufacturing precision
If multiple layers of polarizers and filters are used in LCDs to achieve image quality, then picture quality is improved, but light efficiency deteriorates to below 10%
Solution Approach 1:
The invention extracts and eliminates the need for multiple polarizer and filter layers by using a different fundamental approach: total internal reflection in a waveguide structure with multi-facet light extraction. This removes the light-blocking layers while maintaining picture quality through precise optical control at the facets.
Solution Approach 2:
The patent replaces the mechanical/optical system of LCDs (polarizers, liquid crystal layers, filters) with a waveguide-based system using total internal reflection and geometric optics at multi-facet surfaces. This substitution achieves comparable or superior picture quality with dramatically improved light efficiency.
4Ease of operation
If liquid crystal layers are used for light modulation, then image display capability is achieved, but response time increases causing motion artifacts
Solution Approach 1:
The invention replaces the slow liquid crystal modulation mechanism with fast micro-electro-mechanical (MEMS) mirrors or electro-optic modulators at the waveguide facets. These alternative modulators respond in microseconds or faster, eliminating motion artifacts while maintaining full image display capability including color and grey scale.
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 effectively addresses optical crosstalk and enhances light efficiency and picture quality, achieving high contrast and competitive performance with LCDs in terms of light efficiency, picture quality, and cost.
Implementation Method 1
Light from a light source is introduced to the waveguide from one or more sides of the wave guide and is confined within the waveguide by total internal reflections
Implementation Method 2
the prism film redirects light emitting from the display at oblique angles towards the normal so as to improve the viewing angles
Implementation Method 3
the majority of the viewing surface is coated with a light-absorbing coating
Data Source
AI summary
A display including a light source for generating light, an optical waveguide for receiving and evenly distributing light in a light propagation direction by total internal reflections and a matrix of picture elements constructed on the upper surface of the waveguide, the picture elements including electrically activated micro-mechanical actuators having optical properties for modulating light to produce an image.