OLED Subpixel Area Balancing for Lifetime Uniformity

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Solution Overview

Problem

Existing organic light emitting diode array substrates have sub-pixels of different colors with varying lifetimes, leading to uneven performance and short overall lifespan, as red and blue sub-pixels degrade faster than green sub-pixels, limiting the utilization of green sub-pixel performance.

Innovation Solution

The array substrate is designed with sub-pixels of different colors (green, red, and blue) arranged in specific geometric shapes and sizes, where the longer-lived green sub-pixels have smaller areas and the shorter-lived red and blue sub-pixels have larger areas, allowing for balanced lifetimes and improved resolution by adjusting their sizes based on luminous efficiency and human sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If all sub-pixels are made the same size for simple structure, then manufacturing is easier, but red and blue sub-pixels degrade faster due to shorter lifetime

Engineering Contradiction:
Improvestructure simplicityVSAvoidsub-pixel lifetime balance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by making different sub-pixels have different areas according to their specific characteristics. Green sub-pixels have smaller areas while red and blue sub-pixels have larger areas, allowing each color to operate at optimized current densities that balance their different lifetimes and luminous efficiencies.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the physical parameter of sub-pixel area to resolve the lifetime imbalance. By adjusting the area parameters of red, green, and blue sub-pixels differently, the current density distribution is optimized to compensate for the shorter lifetime of red and blue sub-pixels compared to green sub-pixels.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If red and blue sub-pixels have larger areas to compensate for shorter lifetime, then lifetime balance improves, but manufacturing complexity increases

Engineering Contradiction:
Improvesub-pixel lifetime balanceVSAvoidsub-pixel structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces asymmetry in the sub-pixel design by making red, green, and blue sub-pixels have different areas. This asymmetric design compensates for the different lifetimes and luminous efficiencies of different colors, with red and blue sub-pixels having larger areas than green sub-pixels to balance their shorter lifetimes.

Inventive Principle:
Principle #4Asymmetry

3Duration of action of stationary object

If sub-pixel areas are optimized for lifetime balance, then overall array substrate lifespan is prolonged, but resolution may be affected

Engineering Contradiction:
Improvearray substrate lifespanVSAvoiddisplay resolution
Core Design Contradiction:
Duration of action of stationary objectVSManufacturing precision

Solution Approach 1:

The patent optimizes the area parameters of different sub-pixels to balance lifetimes while maintaining resolution. By carefully calculating and setting the area ratios of red, green, and blue sub-pixels, the design achieves both prolonged array substrate lifespan and acceptable display resolution through compensated current density distribution.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3203520B1Organic light-emitting diode array substrate and display device
Publication Date: 2020.05.13 BOE TECHNOLOGY GROUP CO LTD
  • EP3203520B1 patent drawingFigure 1~2
  • EP3203520B1 patent drawingFigure 3~4

AI summary

The present invention provides an organic light emitting diode array substrate, and a display device, which belongs to the field of display technology, and can solve the problem that the sub-pixels of different colors in the existing organic light emitting diode array substrate have different life times. The organic light emitting diode array substrate of the present invention comprises a plurality of sub-pixels having light emitting layers, the sub-pixels comprising first color sub-pixels, second color sub-pixels and third color sub-pixels with the same amount, and the first color sub-pixels are in a diamond shape; the second color sub-pixels and the third color sub-pixels are in a parallelogram shape, and lengths of their short sides are equal to a side length of the first color sub-pixels, lengths of their long sides are both greater than the side length of the first color sub-pixels.