Optical System for Pupil Guidance in AR Displays
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Solution Overview
Problem
Existing image display devices struggle to display high-resolution, large-size images while maintaining see-through properties, are prone to image invisibility due to eye movement or changes in interpupillary distance, and have an unfavorable external appearance due to size and design constraints.
Innovation Solution
An image display device incorporating a light source optical system, a mirror to reflect light, a light scanning device, a pupil magnifying optical system to enlarge the light beam, a correcting optical system to correct aberrations, and a deflecting optical system, such as a holographic mirror, to guide light to the exit pupil, ensuring see-through capabilities and reducing device size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a holographic optical element is used to transmit outdoor light, then see-through property is improved, but aberration and distortion cannot be corrected, resulting in poor image quality
Solution Approach 1:
The optical system is divided into multiple functional elements: a first optical system (holographic optical element) for see-through property and a second optical system (lens system) for aberration correction. This segmentation allows each subsystem to optimize its specific function without compromising the other, resolving the contradiction between see-through property and image quality.
Solution Approach 2:
A lens system is introduced as an intermediary component between the holographic optical element and the viewer's eye. This intermediate optical system corrects the aberrations and distortion caused by the holographic element while allowing the holographic element to maintain its see-through function, thus mediating between conflicting requirements.
2Reliability
If a liquid crystal display element is used, then video display is achieved, but the display element size becomes great
Solution Approach 1:
The patent replaces the liquid crystal display element with a light scanning system that uses a light source and scanning mechanism. This substitution eliminates the need for large-area display elements while achieving the same video display function through temporal and spatial modulation of light, thus reducing the stationary object area.
Solution Approach 2:
The light scanning system uses periodic scanning motion to project images sequentially. By using time-multiplexed scanning rather than simultaneous pixel activation, the system achieves video display capability without requiring a large physical display area, as the scanning process creates the image perception through temporal sequencing.
3Area of stationary object
If scanning means is used to drive a mirror, then display element size is reduced, but the laser beam shifts from the pupil position when the eye moves, making the image invisible
Solution Approach 1:
The system introduces a second optical system with a lens that dynamically adjusts the beam path to compensate for eye movement. The lens system focuses the scanned laser beam back onto the pupil position even when the eye moves, maintaining image visibility through dynamic optical correction rather than fixed scanning geometry.
Solution Approach 2:
The optical system changes the beam parameters (focus position, beam diameter) through the lens system to adapt to different eye positions. By adjusting these optical parameters dynamically, the system maintains proper beam alignment with the moving pupil, preventing image invisibility while keeping the display element compact.
4Reliability
If a light guiding plate is used to spread image light, then pupil magnifying function is achieved, but the device increases in size and has unfavorable external appearance
Solution Approach 1:
The patent replaces the light guiding plate with a lens system that achieves the same pupil magnifying function through optical refraction rather than mechanical light spreading. This substitution maintains the functional capability while eliminating the bulky external structure, improving external appearance.
Solution Approach 2:
The lens system changes the optical parameters (beam diameter, focus position) to achieve pupil magnification without requiring a light guiding plate. By controlling these optical parameters through the lens, the system achieves the same functional effect with a more compact and aesthetically pleasing design.
5Reliability
If a diffraction grating is disposed between a concave mirror and the eye, then pupil magnifying function is exhibited, but the see-through property is impaired
Solution Approach 1:
The optical system is segmented into distinct functional zones: the first optical system (holographic element) maintains see-through property in one region, while the second optical system (lens system) provides pupil magnification in another region. This spatial segmentation allows both functions to coexist without interfering with each other, unlike the diffraction grating configuration that compromised see-through property.
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 enables high-quality, large-size image display with excellent wearability and external appearance by correcting aberrations and maintaining see-through properties despite eye movement and interpupillary distance changes, while minimizing device size and weight.
Implementation Method 1
a mirror which reflects the light which is emitted from the light source optical system
Implementation Method 2
a light scanning device which scans the light which is reflected by the mirror to use the light as image light
Implementation Method 3
a pupil magnifying optical system which magnifies a beam diameter of the light which is emitted from the light scanning device
Implementation Method 4
a correcting optical system on which the light which is emitted from the pupil magnifying optical system is incident and which corrects shape and aberration of the image light
Implementation Method 5
a deflecting optical system which deflects the light which is emitted from the correcting optical system to guide the light to a position of an exit pupil and transmits a portion of external light
Data Source
AI summary
An image display device with which it is possible to visually recognize an image while securing the see-through property regardless of eye movements and changes in interpupillary distance, with which it is possible to display a large-size image with high quality, and which is small, has excellent wearability, and has an excellent external appearance.