Liquid Crystal Diffraction Elements for AR Optical Expansion
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Solution Overview
Problem
Augmented reality (AR) glasses currently have insufficient field of view (FOV) and eye box, limiting the ability to display a wide image without changing the user's visual line.
Innovation Solution
An optical element with a light guide plate, incorporating multiple incidence and emission diffraction portions with liquid crystal diffraction layers that have varying in-plane periods and rotation directions, enhancing the diffraction and emission of light to expand the FOV and eye box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light is diffracted by a single incidence diffraction element and a single emission diffraction element, then the structure is simple, but the field of view and eye box are insufficient
Solution Approach 1:
The patent divides the diffraction function into multiple segments by using multiple incidence diffraction elements and multiple emission diffraction elements. Each element handles a specific portion of the light guide plate, and their combined effect expands the field of view while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The patent introduces a new dimension of complexity management by arranging diffraction elements in specific patterns (e.g., first and second incidence diffraction elements with different orientations) to expand the field of view in multiple directions simultaneously, transforming a one-dimensional limitation into a multi-dimensional solution.
2Area of stationary object
If light is diffracted by multiple incidence diffraction elements with different in-plane periods and rotation directions, then the field of view is expanded, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies different in-plane periods and rotation directions to different regions of the light guide plate. Each incidence diffraction element is optimized for its specific location and function, allowing local customization that expands the eye box while managing overall manufacturing precision through region-specific optimization rather than uniform high-precision requirements.
Solution Approach 2:
The patent utilizes parameter changes in the liquid crystal alignment patterns (varying in-plane periods and rotation directions) to control the diffraction characteristics of each element. By systematically varying these parameters across different elements, the patent expands the eye box while managing manufacturing precision through controlled parameter progression rather than requiring all elements to meet identical stringent specifications.
3Adaptability or versatility
If multiple incidence diffraction portions and emission diffraction portions are used, then the field of view and eye box are widened, but the device complexity increases
Solution Approach 1:
The patent designs the multiple incidence and emission diffraction elements to work together as a unified system that provides multiple functions: expanding field of view, widening eye box, and maintaining image quality. The elements are configured to cooperate synergistically, allowing a single optical element to perform multiple functions that would otherwise require separate components.
Solution Approach 2:
The patent arranges the multiple diffraction elements in a nested or integrated configuration within the light guide plate structure. The incidence and emission diffraction portions are positioned and oriented to work together in a coordinated manner, creating a compact integrated system that achieves enhanced adaptability without proportionally increasing overall device complexity.
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 allows for a wider field of view and eye box in AR glasses, enabling the display of images without requiring users to change their visual line, thereby improving the overall AR experience.
Implementation Method 1
light (projection light) projected from a display is diffracted (refracted) using a diffraction element to be incident into one end part of a light guide plate
Implementation Method 2
light (projection light) projected from a display is diffracted (refracted) using a diffraction element
Implementation Method 3
the liquid crystal diffraction layer has a liquid crystal alignment pattern in which a direction of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction
Data Source
AI summary
An optical element includes a light guide plate, an incidence portion, and an emission portion, in which each of the incidence portion and the emission portion includes diffraction portions, the diffraction portion includes diffraction elements, the diffraction element includes a liquid crystal diffraction layer in which a direction of an optical axis of a liquid crystal compound changes while continuously rotating in one in-plane direction, and in a case where the direction in which the direction of the optical axis changes is set as an in-plane rotation direction and a length over which the optical axis rotates by 180° is set as an in-plane period, in-plane rotation directions of liquid crystal diffraction layers of incidence diffraction elements in at least two of a plurality of the incidence diffraction portions are different from each other.