Rotating Waveguide HUD Expander for a Larger Eye Box
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Solution Overview
Problem
Existing virtual display devices have a limited eye box size, which restricts the viewing angle and makes it difficult to manufacture large out-coupling elements without increasing production costs.
Innovation Solution
A display apparatus with an expander device that includes a waveguide plate, an in-coupling element, and an out-coupling element, where the expander device is rotatably arranged with respect to a base and driven by a motor to provide a large light-emitting display region, effectively enlarging the eye box without the need for large out-coupling elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of out-coupling element is increased to enlarge eye box, then the eye box size is improved, but the manufacturing difficulty and cost increase
Solution Approach 1:
The expander device is made rotatable around an axis, transforming a static optical system into a dynamic one. The rotation enables a small out-coupling element to sweep across a large area, effectively creating a large eye box without requiring a physically large out-coupling element, thus resolving the manufacturing difficulty while maintaining the improved eye box size
Solution Approach 2:
The invention adds the temporal dimension through rotation, allowing the out-coupling element to occupy multiple positions in space over time. This transforms a two-dimensional area problem into a three-dimensional solution where a small element creates a large effective area through rotational motion, avoiding the need to manufacture large out-coupling elements
2Area of stationary object
If the size of out-coupling element is increased to enlarge eye box, then the eye box size is improved, but the production cost increases
Solution Approach 1:
By making the expander device rotatable, the system uses a small, inexpensive out-coupling element that sweeps through a large area during rotation. This dynamic approach achieves a large eye box effect without the need to manufacture and install expensive large-area out-coupling elements, thereby improving production cost efficiency while maintaining the desired eye box size
Solution Approach 2:
The rotational motion creates multiple virtual copies of the small out-coupling element's optical function across different angular positions. Instead of manufacturing one large physical element, the system uses a small element that replicates its optical function at multiple positions through rotation, significantly reducing production cost while achieving the same effective area
3Ease of manufacture
If a small out-coupling element is used, then the manufacturing is easier and cost is reduced, but the eye box size becomes limited
Solution Approach 1:
The rotatable expander device compensates for the small physical size of the out-coupling element by introducing rotational motion. As the device rotates, the small out-coupling element sequentially occupies multiple angular positions, effectively creating a large eye box area without requiring the element itself to be large, thus maintaining manufacturing ease while achieving the desired eye box size
Solution Approach 2:
The invention transitions from a static two-dimensional area constraint to a dynamic three-dimensional solution. The small out-coupling element rotates around an axis, utilizing the angular dimension to create a large effective eye box area. This dimensional transformation allows a small element to provide a large eye box, resolving the contradiction between manufacturing ease and eye box size
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 provides a large eye box display effect with a small-area exit pupil, allowing for a wider viewing angle and easier mass production using small, slim out-coupling elements, while maintaining high image quality.
Implementation Method 1
an in-coupling element (DOE1) to form guided light (B1) by coupling input light (IN1) into the waveguide plate (SUB1)
Implementation Method 2
an out-coupling element (DOE3) to form output light (OUT1) by coupling the guided light (B1) out of the waveguide plate (SUB1)
Data Source
AI summary
A display apparatus (500) for displaying a virtual image (VIMG1) includes an expander device (EPE1) to form light beams (B3P1,R, B3P2,R) of output light (OUT1) by expanding light beams (B0P1,R, B0P2,R) of input light (IN1), the expander device (EPE1) including a waveguide plate (SUB1), an in-coupling element (DOE1) to form guided light (B1) by coupling input light (IN1) into the waveguide plate (SUB1), and an out-coupling element (DOE3) to form output light (OUT1) by coupling the guided light (B1) out of the waveguide plate (SUB1), wherein the display apparatus (500) includes a base (BASE1) and an actuating mechanism (MOTOR1) to cause rotary and/or oscillatory motion of the waveguide plate (SUB1) with respect to the base (BASE1).