Wearable Pupil-Forming Display with Variable Opacity and Dynamic Focal Length
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wearable augmented reality (AR) display devices face challenges in providing clear, visible virtual images under bright ambient conditions and achieving a balance between visibility of real-world and electronically generated images, while also being compact and aesthetically pleasing.
Innovation Solution
A wearable display apparatus using a pupil-forming optical system with a partially transmissive curved mirror, beam splitter, and spatial light modulator to dynamically adjust opacity and focal length, allowing for improved image quality and brightness compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a pupil expansion method using diffraction is used to create multiple pupil images, then the eye-box is enlarged, but optical efficiency is reduced and chromatic aberrations occur
Solution Approach 1:
The patent divides the optical system into distinct functional components: a beam splitter that separates real-world light from display light, a curved mirror that focuses display light without diffraction, and a spatial light modulator that controls light transmission. This segmentation avoids the diffraction-based pupil expansion method while achieving a large eye-box through geometric optics instead.
Solution Approach 2:
The patent introduces a curved mirror as an intermediary optical element between the display and the user's eye. This curved mirror forms a real image of the display and creates a large exit pupil without the chromatic aberrations and optical efficiency losses associated with diffraction-based pupil expansion methods.
2Area of stationary object
If wave-guide technology is used for pupil expansion, then the eye-box is enlarged, but manufacturing difficulties increase and color dispersion causes chromatic aberrations
Solution Approach 1:
The patent replaces complex wave-guide technology with a simpler optical system consisting of a beam splitter, curved mirror, and spatial light modulator. This substitution eliminates the manufacturing difficulties associated with wave-guides while avoiding chromatic aberrations through the use of reflective and refractive optics rather than diffractive wave-guide structures.
3Volume of moving object
If the optical path is folded to meet compactness requirements, then the device size is reduced, but the imaging system components become harder to position ergonomically
Solution Approach 1:
The patent folds the optical path in multiple dimensions to achieve a compact form factor. The beam splitter is positioned at an angle to the display, and the curved mirror is positioned to reflect light at a different angle, creating a three-dimensional optical path that fits within a compact wearable form while maintaining proper ergonomic positioning of all components.
4Volume of moving object
If the display is positioned close to the eye for compactness, then the device is more compact, but heat from the display contacts the user's skin
Solution Approach 1:
The patent introduces air spaces and thermal management structures as intermediaries between the display and the user's skin. The optical design allows for positioning the display close to the eye while maintaining thermal separation through the optical path geometry and housing design, preventing direct heat contact with the user's skin.
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 provides clear and visible virtual images under bright conditions, maintains unobstructed see-through visibility, and ensures a compact, aesthetically acceptable design, addressing the limitations of existing AR systems.
Implementation Method 1
a beam splitter disposed to reflect light toward the curved mirror surface
Implementation Method 2
a partially transmissive mirror having a curved reflective surface
Implementation Method 3
relay the formed 2D image at the image generator to a curved focal surface of the partially transmissive mirror
Implementation Method 4
a spatial light modulator configured with addressable array of pixels for selectively changing opacity for visible light from the object field
Data Source
AI summary
A wearable display apparatus has an image generator that is energizable to form a 2D image; a partially transmissive mirror having a curved reflective surface; a beam splitter disposed to reflect light toward the curved mirror surface; and an optical image relay that is configured to relay the formed 2D image at the image generator to a curved focal surface of the partially transmissive mirror, wherein the curved focal surface is defined between the curved reflective surface of the partially transmissive mirror and the beam splitter, wherein the relay, curved mirror, and beam splitter are configured to form an exit pupil for viewing the generated 2D image as an optical virtual image; and a spatial light modulator configured with addressable array of pixels for selectively changing opacity for visible light from the object field according to dimensions of the generated 2D image.