Microstructured Cover Plate for Brighter High-Contrast MicroLED Displays

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Solution Overview

Problem

MicroLED displays suffer from low brightness and poor image contrast in ambient light due to reflections from backplane structures and light trapped within the substrate and interface layers.

Innovation Solution

The implementation of a display design that includes a backplane, an array of light sources, focusing microstructures, and a cover plate with a microstructure layer and an absorption layer. The focusing microstructures are aligned with the light sources and the cover plate is attached to them, enhancing light extraction and suppressing ambient light reflection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If microLED displays are used to achieve high ambient contrast by suppressing ambient reflections, then ambient contrast is improved, but a significant amount of optical energy is trapped and absorbed within the display structure resulting in low brightness

Engineering Contradiction:

Improvedisplay brightnessVSAvoidoptical energy trapped and absorbed

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The cover plate is segmented into multiple functional layers: a microstructure layer with light-trapping features and an absorption layer with light-absorbing material. This segmentation allows different regions to perform different functions - the microstructure layer redirects trapped light while the absorption layer selectively absorbs ambient reflections, together resolving the contradiction between brightness and contrast

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The absorption layer is positioned specifically on the inner surface of the cover plate facing the microLEDs, creating a localized light-absorbing region. This local quality enhancement allows the display to absorb ambient reflections at the critical interface while maintaining light emission properties, thereby improving ambient contrast without sacrificing overall brightness

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If the cover plate includes a microstructure layer and an absorption layer to suppress ambient light reflection, then ambient contrast is improved, but the device complexity increases

Engineering Contradiction:

Improveambient contrastVSAvoidcover plate structure

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The microstructure layer and absorption layer are merged into a single integrated cover plate assembly, where the two layers work synergistically. The microstructure layer provides light redirection while the absorption layer provides selective absorption, and their combination achieves superior ambient contrast enhancement without requiring separate external components

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cover plate is designed as a multi-functional component that simultaneously serves as a protective cover, a light management element, and an ambient reflection suppressor. The microstructure layer and absorption layer together provide multiple optical functions (light extraction enhancement, ambient reflection suppression, and directional control) within a single component, reducing overall device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 design significantly improves light extraction and ambient contrast by directing light forward, homogenizing it, and trapping ambient light, thereby enhancing display brightness and contrast.

Implementation Method 1

The microstructure layer and the absorption layer within the displays suppress ambient light reflection (e.g., by up to about 100 times) by trapping incident light in the cover plate by total internal reflection (TIR)

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

The focusing microstructures direct light from light sources forward and homogenize and increase light exiting the display

Methodology Applied

Scientific EffectLight refraction and focusing: Refraction

Implementation Method 3

The absorption layer is arranged on the microstructure layer facing the array of light sources

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20250031499A1Displays including microstructures and methods for fabricating the displays

Publication Date: 2025.01.23 CORNING INC

AI summary

A display includes a backplane, an array of light sources coupled to the backplane, and a cover plate arranged over the array of light sources. The cover plate includes a first side facing the array of light sources and a second side opposite to the first side. The cover plate includes a microstructure layer and an absorption layer. The microstructure layer is arranged on the first side of the cover plate. The absorption layer is arranged on the microstructure layer facing the array of light sources.