Micro LED Display Redundancy Scheme for Power and Yield

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Solution Overview

Problem

Active matrix OLED display panels face challenges in reducing power consumption, which is a significant factor in extending battery life in battery-operated devices, as they tend to be dominant power consumers compared to LCD panels.

Innovation Solution

The implementation of a redundancy scheme using micro LED devices with a semiconductor material, where micro LED device pairs are bonded to a display substrate with a passivation layer to cover irregularities and ensure electrical insulation, allowing for efficient light emission and low power consumption, and an integrated test method to detect and potentially replace defective micro LED devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If AMOLED display panels are used to achieve better image quality, then image quality is improved, but power consumption increases

Engineering Contradiction:
Improveimage qualityVSAvoidpower consumption
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent changes the material parameter of the light-emitting component from organic materials (AMOLED) to inorganic micro LED materials, which fundamentally alters the energy efficiency characteristics while maintaining the light emission function and image quality

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent substitutes the organic electroluminescence mechanism with a solid-state micro LED light emission mechanism, replacing the chemical/organic system with an inorganic semiconductor system that consumes less power

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by moving object

If micro LED devices are used to reduce power consumption, then power consumption is reduced, but manufacturing complexity increases due to integration challenges

Engineering Contradiction:
Improvepower consumptionVSAvoidintegration complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent segments the micro LED devices into discrete transferable units that can be individually placed onto the TFT substrate, allowing for modular integration that simplifies the overall manufacturing process despite the advanced technology involved

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a transfer substrate as an intermediary carrier that holds the micro LED devices during fabrication, enabling easy transfer and integration onto the final display substrate without direct complex bonding processes

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a redundancy scheme is implemented to compensate for defective devices, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvedisplay reliabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a redundancy scheme where additional micro LED devices are pre-positioned on the transfer substrate alongside the functional devices, providing backup components that can compensate for any defects without requiring complex post-manufacturing repairs

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent creates redundant copies of micro LED devices on the transfer substrate, where backup devices are placed in addition to the primary functional devices, allowing substitution if defects are detected during integration

Inventive Principle:
Principle #26Copying

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 reduces power consumption by utilizing highly efficient micro LED devices and a redundancy scheme that compensates for defective devices, enhancing emission uniformity across the display panel without altering the underlying TFT architecture, thereby extending battery life in portable devices.

Implementation Method 1

micro LED devices which are formed of a semiconductor material and have a maximum width of 1 to 100 µm

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2973715B1Light emitting diode display with redundancy scheme
Publication Date: 2021.10.27 APPLE INC
  • EP2973715B1 patent drawingFigure 1
  • EP2973715B1 patent drawingFigure 2
  • EP2973715B1 patent drawingFigure 3A

AI summary

A display panel and method of manufacture are described. In an embodiment, a display substrate includes a pixel area and a non-pixel area. An array of subpixels and corresponding array of bottom electrodes are in the pixel area. An array of micro LED devices are bonded to the array of bottom electrodes. One or more top electrode layers are formed in electrical contact with the array of micro LED devices. In one embodiment a redundant pair of micro LED devices are bonded to the array of bottom electrodes. In one embodiment, the array of micro LED devices are imaged to detect irregularities.