Shared Micro-LED Projection With Polarization-Routed AR/VR Displays
Solution Overview
Problem
Existing augmented and virtual reality display systems face challenges in providing comfortable, natural-feeling presentations of virtual image elements due to bulkiness, weight, frame rate limitations, and viewing discomfort caused by motion blur and optical artifacts, particularly when using transmissive or reflective spatial light modulators and scanning-fiber displays.
Innovation Solution
The use of emissive micro-displays, such as micro-LEDs, with a shared light projection system and an optical router that time-multiplexes left and right eye images, combined with polarization-sensitive reflectors and waveguides, allows for a compact form factor, high frame rates, and reduced motion blur, while maintaining image quality and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If transmissive or reflective spatial light modulators and scanning-fiber displays are used, then display functionality is achieved, but device bulkiness and weight increase
Solution Approach 1:
The patent merges the light source and spatial light modulator into a single integrated emissive micro-display unit. Each micro-display element emits light directly without requiring separate transmissive or reflective optical components, thereby eliminating bulkiness while maintaining display functionality.
Solution Approach 2:
The patent extracts and eliminates the bulky transmissive or reflective spatial light modulators and scanning-fiber components by replacing them with self-emissive micro-display elements that generate light directly, reducing overall device size and weight.
2Speed
If conventional display systems are used, then image presentation is achieved, but frame rate is limited and motion blur occurs
Solution Approach 1:
The patent employs time-multiplexed periodic action where a single shared micro-display sequentially presents left-eye and right-eye images at high frame rates. The optical router rapidly switches between directing light to the left eyepiece and right eyepiece, enabling high frame rate operation that reduces motion blur while maintaining stereoscopic display functionality.
3Weight of moving object
If a shared light projection system is used for both eyes, then device weight is reduced, but optical artifacts may occur
Solution Approach 1:
The patent introduces an optical router as an intermediary component that selectively directs light from the shared micro-display to the appropriate eyepiece. This intermediary mechanism enables weight reduction through shared optics while preventing optical artifacts by ensuring proper light routing to the correct eye at the correct time.
Solution Approach 2:
The patent employs dynamic switching of the optical router to adaptively direct light to the left or right eyepiece based on the current display frame. This dynamic control allows a single shared light projection system to function effectively for both eyes without causing optical artifacts, as the system adapts its light routing in real-time.
4Speed
If high frame rates are achieved through time-multiplexed emission, then motion blur is reduced, but device complexity increases
Solution Approach 1:
The patent designs the optical router to serve multiple functions: it acts as both a light switching mechanism and a synchronization control device. This multi-functional approach enables high frame rate time-multiplexed operation while minimizing device complexity, as the optical router handles both light routing and temporal coordination without requiring additional complex control systems.
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
This approach enables a lightweight, high-frame-rate display system that reduces motion blur and optical artifacts, providing a more comfortable and immersive augmented and virtual reality experience by efficiently directing image light to the left and right eyes with minimal bulkiness and weight.
Implementation Method 1
polarization-sensitive reflectors and waveguides
Implementation Method 2
optical router that time-multiplexes left and right eye images
Implementation Method 3
combined with polarization-sensitive reflectors and waveguides
Data Source
AI summary
A wearable display system includes a light projection system having one or more emissive micro-displays, e.g., micro-LED displays. The light projection system projects time-multiplexed left-eye and right-eye images, which pass through an optical router having a polarizer and a switchable polarization rotator. The optical router is synchronized with the generation of images by the light projection system to impart a first polarization to left-eye images and a second different polarization to right-eye images. Light of the first polarization is incoupled into an eyepiece having one or more waveguides for outputting light to one of the left and right eyes, while light of the second polarization may be incoupled into another eyepiece having one or more waveguides for outputting light to the other of the left and right eyes. Each eyepiece may output incoupled light with variable amounts of wavefront divergence, to elicit different accommodation responses from the user's eyes.