Image Expansion Optic With Flat and Curved Reflectors for See-Through Displays
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Solution Overview
Problem
Existing head-mounted displays (HMDs) with see-through capabilities face challenges in optimizing the user experience by effectively presenting digital content without obstructing the view of the environment, particularly in ensuring clear and unobstructed see-through transmission and enhancing user interaction.
Innovation Solution
A head-worn display system with a display panel positioned to present digital content in a portion of the field of view, using a processor to shift content into blank areas and adjust convergence distance based on user interaction, combined with compact optics that include a reflective display and a partially reflective partially transmissive surface to enhance image quality and provide a see-through view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If digital content is presented in the middle portion of the field of view, then user interaction and focus are improved, but the see-through transmission and environmental visibility are reduced
Solution Approach 1:
The display system applies different optical properties to different regions of the display panel. The middle portion presents digital content with higher brightness and contrast for user interaction, while the edge portions maintain higher transparency for environmental visibility. This spatial differentiation of optical characteristics resolves the contradiction between content presentation and see-through capability.
2Measurement precision
If the display system provides high-contrast digital content, then readability is improved, but stray light and visual discomfort increase
Solution Approach 1:
The display field is segmented into multiple zones with different optical characteristics. The central display region provides high-contrast content for readability, while peripheral regions and optical paths incorporate light management structures that redirect or absorb stray light. This segmentation allows high-contrast content presentation without overwhelming the user with stray light.
3Volume of moving object
If the optical system is made compact, then device size is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
Multiple optical functions are merged into integrated components. The waveguide structure combines light entry, internal propagation, and display presentation functions. The display panel integrates content generation with optical modulation. This merging reduces the overall number of discrete components and assembly steps, making compact design more manufacturable.
4Area of stationary object
If the display panel covers the entire field of view, then digital content coverage is maximized, but the see-through view of the environment is obstructed
Solution Approach 1:
The display system transitions from a planar occluding surface to a volumetric waveguide structure. Light enters the waveguide at one surface, propagates through the bulk material, and is presented at another surface. This dimensional transition allows the display to occupy optical space without blocking the line of sight, enabling full field of view coverage with maintained environmental visibility.
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 system improves user experience by providing clear, high-contrast digital content with adjustable convergence and position, enhancing the see-through view and reducing stray light, while maintaining a compact and cost-effective design.
Implementation Method 1
compact optics that include a reflective display and a partially reflective partially transmissive surface
Implementation Method 2
partially reflective partially transmissive surface to enhance image quality and provide a see-through view
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.