Asymmetric RGB MicroLED Microlens Layout for Ghost Artifact Reduction
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Solution Overview
Problem
Monolithic RGB microLED panels in augmented reality displays face challenges with optical efficiency and ghost panel artifacts due to varying light coupling efficiencies and reflections, particularly with red, green, and blue wavelengths, leading to visual distortions and inefficiencies in light transfer.
Innovation Solution
Implementing an offset and asymmetric microlens array on the microLED panel to align the optical axis with the red pixel, optimizing light collection and distribution to minimize rebounce losses and uniformity of light coupling across RGB channels, thereby enhancing overall efficiency and reducing ghost panel artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a symmetric microlens array is used, then manufacturing is simpler, but light coupling efficiency is non-uniform across RGB channels causing ghost artifacts
Solution Approach 1:
The patent applies asymmetry by offsetting the microlens array relative to the pixel array, specifically aligning the optical axis with the red pixel center rather than the green pixel center. This asymmetric configuration compensates for the longer optical path of red light, achieving uniform light coupling efficiency across all RGB channels and eliminating ghost artifacts while maintaining manufacturability
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 improves light collection and reduces ghost panel artifacts, resulting in higher optical efficiency and clearer image quality in augmented reality displays by aligning the microlens array with the red pixel to minimize rebounce losses and enhance uniformity of light coupling.
Implementation Method 1
a lens with a relatively large numerical aperture may be used, however, constraints on display size, weight, and cost often make it unfeasible
Implementation Method 2
light, initially reflected from the input coupler (IC) within the waveguide, re-enters the light engine. Subsequently, this light is reflected by the display panel and manages to return to the IC, ultimately coupling back into the waveguide
Data Source
AI summary
An augmented reality (AR) display includes a light engine having a three-color microscopic light-emitting diode (microLED) panel and an array of microlenses disposed at the three-color microLED panel and configured to redirect collimated projected light from the three-color microLED panel to an exit pupil of the light engine. A microlens of the array of the microlenses partially covers a pixel of the three-color microLED panel so that a red pixel of the three-color microLED panel is substantially aligned with an optical axis of each microlens and a blue pixel and a green pixel are substantially offset from the microlens. A waveguide of the AR display includes an input coupler (IC) with an entrance pupil that is substantially coplanar with the light engine.