Image Expansion Optic for See-Through HMD Brightness Uniformity
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Solution Overview
Problem
Existing head-mounted displays (HMDs) with see-through capabilities face challenges in optimizing user experience due to complex content presentation, particularly in transitioning between augmented and virtual reality modes, and require improved systems and methods to enhance user interaction and immersion.
Innovation Solution
The system employs a head-worn display with a display panel and processor that presents digital content in a portion of the field of view, with blank areas on opposing edges, allowing for adjustment of convergence distance and position based on user gaze and content type, using compact optics with reflective displays and polarized light management to enhance clarity and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital content is presented only in the middle portion of the field of view with blank areas on opposing edges, then convergence distance adjustment is enabled, but the field of view area is reduced
Solution Approach 1:
The system dynamically shifts the position of digital content within the field of view based on detected user gaze direction. The processor monitors user eye position and adjusts content placement in real-time, allowing the content to move between the middle portion and blank areas. This dynamic repositioning enables convergence distance adjustment while maintaining an effectively large field of view area, as the blank areas are utilized when needed for focus adjustment rather than being permanently wasted space.
2Volume of moving object
If compact optics with reflective displays are used, then device size is reduced, but optical complexity increases
Solution Approach 1:
The patent combines multiple optical functions into integrated components. The reflective display serves both as the image generation surface and as part of the optical path folding mechanism. The combiner element merges the digital content path with the see-through environment path. By merging these functions into fewer components, the system achieves compact size while managing optical complexity through functional integration rather than adding separate elements for each function.
Solution Approach 2:
The system uses folded optical paths that utilize the third dimension (depth) to route light, allowing compact lateral footprint. By folding the optical path through strategic placement of reflective surfaces and combiner elements at different depths, the system achieves a compact overall device size while maintaining the necessary optical separation and complexity management through spatial arrangement.
3Ease of manufacture
If polarized light management is implemented, then image contrast is improved, but light transmission is reduced
Solution Approach 1:
The system applies polarized light management selectively to specific regions of the optical path, particularly at the reflective display and combiner interfaces where polarization control most effectively enhances contrast. By localizing the polarization control rather than applying it uniformly throughout the entire optical system, the patent maintains high contrast in critical areas while minimizing overall light transmission loss.
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 approach improves user experience by providing adjustable digital content positioning and enhanced image quality, ensuring seamless transitions between augmented and virtual reality modes with improved brightness uniformity and reduced stray light, resulting in higher contrast and immersion.
Implementation Method 1
a reflective display positioned in the middle of the optical assembly
Implementation Method 2
polarized light management to enhance clarity and contrast
Implementation Method 3
project polarized illuminating light towards a partially reflective partially transmissive surface
Implementation Method 4
partially reflective partially transmissive surface such that the illuminating light reflects through a field lens
Implementation Method 5
the illuminating light reflects through a field lens and towards a reflective display
Data Source
AI summary
A head-worn see-through display includes a display panel adapted to generate image content light, a combiner adapted to reflect the image content light towards an eye of a user, wherein the combiner transmits scene light from a surrounding environment to the eye of the user, and an image expansion optic intermediate the display panel and the combiner. The image expansion optic includes a flat partially reflective and partially reflective surface (the “flat surface”), a curved partially reflective and partially reflective surface (the “curved surface”), and the flat surface adapted to reflect the image content light towards the curved surface and the curved surface adapted to reflect the image light back towards the flat surface, wherein the image light transmits through the flat surface towards the combiner.