Optical Combiner Structure for Multi-User HUD Eye-Box Expansion
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Solution Overview
Problem
Conventional display systems face limitations in providing a wide field of view and comfortable viewing angles, especially in applications like head-up displays, where the viewer's eye position significantly affects the visibility of the projected image, and there is a need to display separate images to multiple users without obstructing the view of one user from another.
Innovation Solution
A display system utilizing waveguide pupil expanders to increase the field of view and eye-box size, combined with a diffractive structure to project separate images to different users, allowing for augmented reality for one user and non-augmented reality for another, using a common optical combiner that appears transparent to one user and opaque to the other.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional display system is used, then the image can be displayed, but the field of view and eye-box size are limited
Solution Approach 1:
The patent introduces waveguide pupil expanders that utilize optical waveguiding in a third dimension (depth) to expand the eye-box size. The waveguides transport light laterally while maintaining optical path control, effectively increasing the viewing area without expanding the physical footprint of the display device in the plane dimensions.
Solution Approach 2:
The waveguide acts as an intermediary optical element between the display device and the viewer's eye. It mediates the light transport process by guiding light from the display plane to expanded viewing positions, enabling multiple eye positions to access the full image without direct line-of-sight requirements.
2Adaptability or versatility
If separate images are displayed to multiple users, then each user receives customized content, but the device complexity increases
Solution Approach 1:
The patent segments the optical combiner surface into multiple distinct eye-box regions, each associated with a specific viewer. The diffractive structure is correspondingly segmented to direct different holographic content to each segmented region, enabling multi-user display through spatial segmentation rather than requiring separate display devices.
Solution Approach 2:
The optical combiner serves multiple functions simultaneously: it acts as a beam splitter for holographic projection, a waveguide coupling interface, and a viewing surface for multiple users. The diffractive structure on the combiner performs multiple functions by directing different wavelengths or angles to different eye-boxes, enabling one component to serve multiple users with different content.
3Illumination intensity
If a viewing screen is used for one user, then large clear images can be displayed, but it obstructs the view of another user
Solution Approach 1:
The optical combiner exhibits different optical properties at different locations: in the first eye-box region, it appears transparent to allow ambient light passage and real-world viewing, while in the second eye-box region, it functions as an opaque viewing screen for the virtual image. This spatial variation in optical properties resolves the contradiction between displaying bright images and maintaining unobstructed views.
Solution Approach 2:
The optical properties of the combiner are dynamically adjusted based on viewing angle and position. The combiner transitions between transparent and opaque states depending on the viewer's location relative to the different eye-boxes, enabling the same physical component to serve contradictory functions for different users simultaneously.
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
Enables large, clear images to be displayed comfortably for one user without obstructing the view of another, maintaining the driver's field of view in a vehicle HUD system, and allowing separate images to be projected without distraction.
Implementation Method 1
A display system utilizing waveguide pupil expanders to increase the field of view and eye-box size
Implementation Method 2
combined with a diffractive structure to project separate images to different users
Implementation Method 3
using a common optical combiner that appears transparent to one user and opaque to the other
Implementation Method 4
The optical combiner is transmissive and the structure is substantially transmissive when viewed from the first eye-box
Data Source
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AI summary
A display system comprising an optical combiner. The optical combiner is arranged to form a surface for a first eye-box for a first user and a second eye-box for a second user and is transmissive. The display system further comprises a structure arranged in cooperation with a sub-area of the optical combiner. The structure is or appears substantially transmissive when viewed from the first eye-box and substantially opaque when viewed from the second eye-box.