Liquid Crystal Coupler Waveguide AR Display
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Solution Overview
Problem
Augmented reality glasses with optical combiners using waveguide elements and gratings suffer from low ambient light penetration, ghost images, reduced light efficiency, and color crosstalk due to diffraction effects, which affect their yield and commonality.
Innovation Solution
A display device comprising a light source, a waveguide element, a liquid crystal coupler, and two holographic optical elements, where the liquid crystal coupler adjusts the incident angle of light to the first holographic optical element, and the second holographic optical element diffracts the light to concentrate energy and achieve high optical efficiency, field of view, and Eye Box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a waveguide element and a geometric grating are used as optical combiner, then the structure achieves compact form factor, but ambient light penetration is low and ghost images are generated
Solution Approach 1:
The patent extracts the geometric grating from the optical combiner structure and replaces it with a liquid crystal coupler. This removal of the problematic geometric grating eliminates the ghost images and improves ambient light penetration while maintaining the compact waveguide-based form factor.
Solution Approach 2:
The patent changes the optical parameter of the coupler from a fixed geometric grating to a liquid crystal-based variable optical element. This parameter change enables dynamic control of light paths, improving both ambient light penetration and eliminating ghost images while maintaining compact dimensions.
2Volume of moving object
If a waveguide element and a diffraction grating are used as optical combiner, then the structure achieves compact form factor, but light efficiency is reduced due to light dispersion
Solution Approach 1:
The patent removes the diffraction grating from the optical combiner and replaces it with a liquid crystal coupler. This extraction eliminates the light dispersion problem and improves light efficiency while maintaining the compact waveguide structure.
Solution Approach 2:
The patent converts the potentially harmful light dispersion effect into a beneficial focused light path by using the liquid crystal coupler's variable optical properties. This transforms what would be energy loss into controlled light directionality, improving overall light efficiency.
3Volume of moving object
If three volumetric holographic gratings are stacked on the waveguide element, then the form factor is small, but color crosstalk occurs between different wavelengths
Solution Approach 1:
The patent extracts the stacked volumetric holographic gratings from the optical combiner and replaces them with a liquid crystal coupler. This removal eliminates color crosstalk between different wavelengths while maintaining the compact form factor enabled by the waveguide architecture.
Solution Approach 2:
The patent applies local quality control by using the liquid crystal coupler to independently control light paths for different wavelengths at specific locations within the waveguide, preventing color crosstalk while maintaining compact dimensions through localized optical management.
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 concentration, reduces dispersion, and achieves high optical efficiency, field of view, and Eye Box, addressing issues of low ambient light penetration and diffraction-related inefficiencies in augmented reality glasses.
Implementation Method 1
The liquid crystal coupler is configured to change an incident angle that the light emits to the first holographic optical element
Implementation Method 2
the liquid crystal lens group is configured to change an optical axis direction of the first lens by adjusting an electric field of the first liquid crystal layer
Implementation Method 3
the first holographic optical element is configured to diffract the light to be totally reflected in the waveguide element
Implementation Method 4
the first holographic optical element is configured to diffract the light to be totally reflected in the waveguide element
Implementation Method 5
the second holographic optical element is configured to diffract the light to the waveguide element below
Implementation Method 6
the second holographic optical element is configured to diffract the light to concentrate energy and achieve high optical efficiency
Data Source
AI summary
A display device includes a light source, a waveguide element, a liquid crystal coupler, a first holographic optical element and a second holographic optical element. The light source is configured to emit light. The waveguide element is located above the light source. The liquid crystal coupler is located between the waveguide element and the light source. The first holographic optical element is located on a top surface of the waveguide element, in which the liquid crystal coupler is configured to change an incident angle that the light emits to the first holographic optical element. The second holographic optical element is located on the top surface of the waveguide element, and there is a first distance in a horizontal direction between the first holographic optical element and the second holographic optical element, in which the second holographic optical element is configured to diffract the light to the waveguide element below.