Diffractive Light Guide Plate for Large Viewing Angle
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Solution Overview
Problem
Diffractive light guide plates used in augmented, mixed, and virtual reality displays face limitations in forming large viewing angles and eye motion boxes due to the separate positioning of input, intermediate, and output diffractive optical elements, which restricts the size of the optical image and visible region.
Innovation Solution
A diffractive light guide plate design featuring two output diffractive optical elements with different linear grating patterns, alternately arranged in a central region, allowing each element to receive and redirect light from the input diffractive optical element, thereby extending the light in one dimension and forming a larger viewing angle and eye motion box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple diffractive optical elements are disposed separately on the light guide unit, then each element can perform its specific function, but the area occupied by the output diffractive optical element is limited, resulting in a limited output optical image size and visible region
Solution Approach 1:
The output diffractive optical element is divided into multiple segments (first output diffractive optical element and second output diffractive optical element) that can be disposed in different regions of the light guide unit. Each segment processes light independently, allowing the system to achieve a larger effective output area without increasing the complexity of a single element's structure.
Solution Approach 2:
The patent utilizes the two-dimensional surface of the light guide unit more effectively by disposing diffractive optical elements in different spatial regions (different dimensions). The input element and multiple output elements are arranged to utilize both horizontal and vertical spaces, transforming a one-dimensional linear arrangement into a two-dimensional distributed arrangement, thereby increasing the effective area for light processing.
2Adaptability or versatility
If a single output diffractive optical element is used, then the structure is simple, but the visible region is limited due to position deviation of the user's pupil
Solution Approach 1:
The output diffractive optical element is segmented into multiple elements positioned at different locations on the light guide unit. Each segment corresponds to a specific viewing zone, allowing users with different pupil positions (due to head movements or individual anatomical variations) to still access the full optical image within their respective visible regions.
Solution Approach 2:
The multiple output diffractive optical elements collectively provide universal coverage for various user pupil positions. While each individual element serves a specific spatial zone, the combination of all elements ensures that regardless of where the user's pupil is positioned, the full optical image remains visible, making the system adaptable to diverse user conditions.
3Area of stationary object
If diffractive optical elements are arranged to maximize area coverage, then the output optical image size increases, but the position deviation of user's pupil causes limitations in visible region
Solution Approach 1:
The output diffractive optical element is divided into multiple segments distributed across different regions of the light guide unit. This segmentation allows the system to maintain large total area coverage while ensuring that each segment serves a specific spatial zone, thereby accommodating users with varying pupil positions and maintaining broad visible region coverage.
Solution Approach 2:
The patent transitions from a single large-area element to multiple distributed elements across the two-dimensional surface of the light guide unit. This dimensional distribution strategy maximizes area utilization while simultaneously ensuring coverage across different spatial zones, allowing the system to achieve both large output image size and broad visible region coverage for diverse user positions.
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
This design enables the formation of an image light with a larger viewing angle and a longer eye motion box, accommodating various user pupil positions, thus enhancing the display's ability to handle different physical conditions.
Implementation Method 1
a diffractive light guide plate using a diffractive phenomenon based on the wave properties of light
Implementation Method 2
The light guide unit 21 guides lights in an interior by using total internal reflection
Data Source
AI summary
A diffractive light guide plate including a light guide unit; an input diffractive optical element that receives lights output from a light source and diffracts the received lights to be guided on the light guide unit; and two output diffractive optical elements disposed in a predetermined region of the light guide unit and having different linear grating patterns from each other, wherein the two output diffractive optical elements are configured so that each one output diffractive optical element receives the lights from the input diffractive optical element and allows the received lights to be directed to the other output diffractive optical element by diffraction, and so that each one output diffractive optical element receives lights from the other output diffractive optical element and allows the received lights to be output from the light guide unit by diffraction, and the two output diffractive optical elements having different linear grating patterns are alternately arranged in at least one dimension in a central region having at least a predetermined width within the predetermined region and partitioned longitudinally from a side adjacent to the input diffractive optical element to an opposite side thereto.