Waveguide Display Micro-Shutters Ambient Light Contrast
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Solution Overview
Problem
Optical waveguide-based displays suffer from optical crosstalk and reduced contrast at high ambient light levels due to mirror surfaces reflecting ambient light, leading to inefficient light usage and visible motion artifacts.
Innovation Solution
A display design featuring a light source and optical waveguide with tilting micro-shutters and a light-absorbing coating, where light is modulated by selectively directing it to the viewer or an absorber, and utilizing total internal reflections for increased efficiency and dichroic filters for color separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If mirror surfaces are used to redirect light to the viewer, then light can be redirected effectively, but ambient light is reflected back to the viewer reducing contrast at high ambient light levels
Solution Approach 1:
The patent extracts the light redirection function from a continuous mirror surface and relocates it to discrete, localized micro-mirrors positioned only at the light exits. This allows light to be redirected effectively to viewers while the majority of the viewing surface remains light-absorbing, preventing ambient light reflection and maintaining contrast at high ambient light levels.
Solution Approach 2:
The patent applies different surface properties to different locations: the majority of the viewing surface has light-absorbing properties to maintain contrast, while specific localized regions (micro-mirrors at light exits) have light-redirecting properties. This local differentiation resolves the contradiction between effective light redirection and contrast maintenance.
2Object-affected harmful factors
If light-absorbing coating is applied to the viewing surface to maintain contrast, then contrast is maintained at high ambient light levels, but light efficiency decreases
Solution Approach 1:
The patent segments the viewing surface into two functional zones: a light-absorbing background surface that maintains contrast, and discrete light-exit regions with micro-mirrors that efficiently redirect light to viewers. This segmentation allows the system to maintain contrast while minimizing light absorption, thereby preserving light efficiency.
Solution Approach 2:
The patent applies light-absorbing coating only to the majority of the viewing surface away from light exits, while leaving the light exit regions with reflective micro-mirrors. This localized application maintains contrast where needed while preserving light efficiency at the functional light exit areas.
3Ease of operation
If micro-mechanical picture elements are constructed on the waveguide surface, then images can be displayed, but optical crosstalk occurs between simultaneously activated picture elements
Solution Approach 1:
The patent segments the light modulation function into independent micro-mirrors positioned at discrete light exits along the waveguide. Each micro-mirror operates independently to redirect light from its specific location, preventing optical crosstalk between simultaneously activated picture elements while maintaining full image display capability.
4Illumination intensity
If light passes through multiple layers of polarizers and filters in LCD, then color and brightness can be controlled, but overall light efficiency drops below 10%
Solution Approach 1:
The patent replaces the complex multi-layer optical system of polarizers and color filters with a simpler mechanical system of tilting micro-mirrors. These micro-mirrors redirect light mechanically to control which picture elements are illuminated, achieving color and brightness control through spatial light routing rather than optical filtering, thereby dramatically improving light efficiency.
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 enhances light efficiency, reduces optical crosstalk, and maintains high contrast at high ambient light levels, offering improved picture quality and competitiveness with LCDs in terms of light efficiency, cost, and response time.
Implementation Method 1
Light from a light source is introduced to the waveguide from one or more sides of the waveguide and is confined within the waveguide by total internal reflections
Implementation Method 2
Light is extracted from the planar surface of the waveguide by coupling to evanescent waves or by deforming the surface of the planar waveguide to produce an image
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 electromechanical picture elements for modulating light to produce an image.