Diffractive Light Guide Plate for Wide Viewing Angle AR Displays
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Solution Overview
Problem
Diffractive light guide plates for augmented, mixed, and virtual reality displays face limitations in providing wide viewing angles and large eye motion boxes due to the restricted area occupied by output diffractive optical elements, which restricts the size of optical images that can be output.
Innovation Solution
A diffractive light guide plate design featuring a light guide unit with a first diffractive optical element having linear gratings and a second diffractive optical element with a two-dimensional pattern, where the two-dimensional pattern intersects with virtual linear patterns to extend light in two dimensions, allowing for a wider viewing angle and larger eye motion box by efficiently utilizing space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If separate input and intermediate diffractive optical elements are disposed on the light guide unit, then the optical path is well-defined, but the area occupied by the output diffractive optical element is limited, resulting in limited output image size
Solution Approach 1:
The patent combines the input diffractive optical element and intermediate diffractive optical element into a single integrated element. This merging allows the light guide unit to have more available area for the output diffractive optical element, thereby increasing the output image size while maintaining the necessary optical path definition through the integrated element's internal structure
Solution Approach 2:
The patent introduces a wraparound configuration where the output diffractive optical element extends around the edge of the light guide unit. This utilizes the peripheral dimension of the light guide unit that was previously underutilized, effectively increasing the available area for the output element without increasing the overall device footprint
2Adaptability or versatility
If the output diffractive optical element area is increased to output larger optical images, then the viewing angle and eye motion box improve, but the area available for input and intermediate diffractive optical elements decreases
Solution Approach 1:
By merging the input and intermediate diffractive optical elements into a single integrated element, the patent reduces the total area required for these functions, thereby freeing up space for a larger output diffractive optical element that can provide wider viewing angles and larger eye motion box
Solution Approach 2:
The wraparound configuration allows the output diffractive optical element to utilize the peripheral region of the light guide unit, effectively increasing its area without encroaching on the central region where the integrated input/intermediate element is positioned
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 design enables a wide viewing angle and large eye motion box, accommodating various user pupil positions, thereby enhancing the display's responsiveness to 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 and a display device including the same, the diffractive light guide plate including a light guide unit; a first diffractive optical element including a linear grating repeatedly formed at a predetermined pitch; and a second diffractive optical element disposed in a region distinct from a region where the first diffractive optical element is disposed and including a two-dimensional pattern provided in a region where a virtual first linear pattern repeatedly arranged at a predetermined pitch along a first direction and a virtual second linear pattern repeatedly arranged at a predetermined pitch along a second direction intersect each other, where a horizontal section of the two-dimensional pattern has an elliptical shape and an angle between the long axis of the elliptical shape and a direction perpendicular to an extension direction of the linear grating in the first diffractive optical element is less than 20°.