Compact Near Eye Display Using Waveguide for Thin Form Factor
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Solution Overview
Problem
Near eye displays using scanning mirrors and laser light face safety concerns and image quality issues due to speckle, and are cumbersome due to large optics required for projecting virtual images directly into viewers' eyes.
Innovation Solution
A compact near eye display system that uses a waveguide to convey angularly transformed image segments, minimizing thickness and optics size, with scanning optics and a multi-pixel light source to generate virtual images, allowing for reduced angular scan positions and preserving pupil dimensions for a compact form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If scanning mirrors with large focusing optics are used to project virtual images directly into viewers' eyes, then image projection capability is achieved, but the display becomes thick and cumbersome for mounting as eyeglasses or head-mounted devices
Solution Approach 1:
The patent transitions from direct projection of virtual images into the eye to a waveguide-based system where light propagates along the waveguide length rather than requiring large focusing optics in front of the eye. This dimensional change allows the optical system to be flattened into a thin form factor suitable for eyeglass integration.
Solution Approach 2:
The waveguide acts as an intermediary between the light source and the viewer's eye, replacing the need for large focusing optics. The waveguide conveys image information to the eye through total internal reflection, enabling a compact form factor while maintaining image projection capability.
2Reliability
If laser beams are used to write images directly into viewers' eyes, then virtual images can be formed, but safety concerns and speckle degradation occur
Solution Approach 1:
The patent replaces expensive and potentially harmful laser beams with inexpensive, short-lived phosphorescent particles that emit light when excited by ultraviolet illumination. This substitution eliminates laser safety concerns and speckle degradation while maintaining the ability to form virtual images.
Solution Approach 2:
The system changes the fundamental parameter of light generation from coherent laser light to incoherent phosphorescent emission. This parameter change eliminates the coherence-related issues of speckle and safety hazards associated with high-intensity laser beams directed into the eye.
3Productivity
If conventional near eye displays with in-line scanning mirrors are used, then virtual raster scan images can be generated, but large focusing optics are required making the display thick and cumbersome
Solution Approach 1:
The patent uses a waveguide to convey light along its length, transforming the optical path from a direct front-facing projection to a lateral propagation path. This allows the scanning mirrors to be positioned away from the eye, reducing the thickness required in front of the viewer's eye while maintaining virtual image generation capability.
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 the projection of virtual images with improved safety and image quality by reducing the size and thickness of the display, while maintaining image clarity and safety by using a waveguide to propagate image segments efficiently.
Implementation Method 1
convey an angular transform of the image segments along a waveguide toward a viewer's eye
Implementation Method 2
A scanning optic can be arranged to receive the angularly transformed image segments of the first dimension of the intended image and to angularly separate the transformed image segments in a second dimension
Implementation Method 3
an exit coupling of the waveguide can redirect the image segments into the viewer's eye as a virtual image
Data Source
AI summary
A compact near eye display generates image segments for a first dimension of an intended image. Each of the image segments is transformed into angularly distinguished beamlets that converge through a first dimension pupil within an eyebox. A scanning optic angularly separates the angularly distinguished beamlets of different image segments for creating a second dimension pupil. The angularly distinguished and separated beamlets propagate along a waveguide in a form that minimizes the thickness of the display in front of a viewer's eye and limits the overall size of the optics required to support the projection of virtual images into the viewer's eye.