Near-eye display with selectively reflective optic
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Solution Overview
Problem
Near-eye displays that provide see-through views of the ambient environment face challenges in thickness due to the need for powered optics that are either folded out of the line of sight or oriented off-axis, leading to issues with image distortion and chromatic aberration, while also requiring additional optics to maintain a natural view.
Innovation Solution
A near-eye display with a selectively reflective powered optic oriented nominally normal to the line of sight, where the optical paths to and from the optic overlap, reducing image distortion and chromatic aberration, and allowing the image generator to be inclined along the line of sight, resulting in a thinner display design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If powered optics are folded out of the line of sight, then thickness requirements are reduced, but the display thickness increases in another dimension
Solution Approach 1:
The patent folds the optical path using mirrors to redirect light from the image generator through a thin profile. The optical path is bent at right angles using reflective surfaces, allowing the light to travel through a compact volume while maintaining the necessary optical path length. This enables the display to achieve a thin form factor without sacrificing optical performance.
2Length of stationary object
If powered optics are oriented off-axis, then light efficiency is improved and thickness requirements are reduced, but image distortion and chromatic aberration increase
Solution Approach 1:
The patent employs asymmetric optical path folding using mirrors positioned at specific angles. The first and second mirrors create an asymmetric path that redirects light from the image generator through the powered optic and to the display. This asymmetric configuration allows the optic to be positioned off-axis while maintaining proper alignment and minimizing aberrations through careful geometric design.
Solution Approach 2:
The patent introduces mirrors as intermediary elements between the image generator and the powered optic. These mirrors serve as mediators that redirect the optical path, allowing the powered optic to be positioned in a location that minimizes its thickness contribution while maintaining proper optical alignment. The mirrors enable the light to reach the optic at the correct angle without requiring the optic itself to be thick or positioned on-axis.
3Use of energy by moving object
If powered optics are oriented off-axis, then overall light efficiency is improved, but additional optics are required to correct image distortion and chromatic aberration
Solution Approach 1:
The patent designs the optical path folding system to serve multiple functions simultaneously. The same mirror arrangement that directs light efficiently also positions the powered optic to minimize aberrations. The asymmetric path configuration achieves both high light efficiency and reduced need for additional correction optics by carefully designing the geometric relationships between components.
Solution Approach 2:
The patent combines the functions of light redirection and optic positioning into a single integrated optical path design. The mirrors serve both to fold the optical path for compactness and to position the powered optic in an optimal location. This merging of functions reduces the need for separate correction optics while maintaining high light efficiency.
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 configuration enables the construction of a more compact near-eye display by maintaining rotational symmetry and reducing thickness while preserving image quality and natural ambient light transmission.
Implementation Method 1
A selectively reflective powered optic connects first and second optical paths. The first optical path conveys image-bearing light from the image generator to the selectively reflective powered optic, and the second optical path conveys the image-bearing light along a line of sight from the selectively reflective powered optic to the eyebox.
Implementation Method 2
First and second selectively reflective surfaces fold the first optical path with respect to the second optical path to locate the image generator out of the line of sight to the eyebox.
Data Source
AI summary
A near-eye display projects virtual images from an image generator to an eyebox within which the virtual images can be seen by a viewer. A first optical path conveys image-bearing light from the image generator to a selectively reflective powered optic and a second optical path conveys the image-bearing light along a line of sight from the selectively reflective powered optic to the eyebox. First and second selectively reflective surfaces fold the first optical path with respect to the second optical path to locate the image generator out of the line of sight to the eyebox. The image generator is effectively inclined to the line of sight to the eyebox for reducing a thickness of the near-eye display. The selectively reflective powered optic is oriented normal to local overlapping portions of the first and second optical paths at the selectively reflective powered optic.