Sloped Anode Arrangement for OLED Color Symmetry

Solution Overview

Problem

Organic light emitting display devices suffer from color coordinate asymmetry when viewed from different angles, leading to variations in color perception, particularly exhibiting reddish or greenish tints when displaying white due to the tilting of sub-pixel electrodes caused by the step of thin film transistors.

Innovation Solution

The arrangement of sub-pixels with alternating tilting directions of their anodes relative to the substrate, ensuring that adjacent sub-pixels display different colors and have distinct angles with the substrate, thereby minimizing color coordinate fluctuations with viewing angle changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If sub pixels are disposed in the same position with sloped electrodes due to thin film transistor steps, then the device structure is simplified and manufacturing is easier, but color coordinate asymmetry occurs when viewed from different angles

Engineering Contradiction:

Improveease of manufactureVSAvoidcolor coordinate symmetry

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies asymmetry by intentionally designing different tilting directions for electrodes in different sub-pixels. Specifically, red and green sub-pixels have electrodes tilted in opposite directions to compensate for the viewing angle dependence of color perception. This asymmetric arrangement counteracts the natural asymmetry caused by the TFT steps, achieving color coordinate symmetry across different viewing angles while maintaining the simplified same-position sub-pixel structure.

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If electrodes are formed with slopes due to thin film transistor steps, then the device complexity is reduced, but color perception varies according to viewing angle

Engineering Contradiction:

Improvedevice complexityVSAvoidcolor consistency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies local quality by assigning different tilting characteristics to electrodes in different sub-pixels based on their specific color emission properties. Red and green sub-pixels have electrodes tilted in opposite directions, while blue sub-pixels have electrodes tilted in the same direction. This localized differentiation optimizes color consistency for each sub-pixel's specific wavelength characteristics, thereby ensuring overall color reliability across the entire display without increasing device complexity.

Inventive Principle:

Principle #3Local quality

3Device complexity

If sub pixels are arranged in the same position, then the pixel structure is simplified, but white color display shows reddish or greenish tints at different viewing angles

Engineering Contradiction:

Improvepixel structure complexityVSAvoidcolor accuracy

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The patent applies asymmetry by intentionally designing different tilting directions for electrodes in different sub-pixels. Specifically, red and green sub-pixels have electrodes tilted in opposite directions to compensate for the viewing angle dependence of color perception. This asymmetric arrangement counteracts the natural asymmetry caused by the TFT steps, achieving color coordinate symmetry across different viewing angles while maintaining the simplified same-position sub-pixel structure.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS10692938B2Light emitting display device sloped electrode

Publication Date: 2020.06.23 LG DISPLAY CO LTD

AI summary

Provided is an light emitting display device including a plurality of pixels on a substrate. Each of the plurality of pixels includes a first sub pixel extending in a first direction, a second sub pixel extending in the first direction, a third sub pixel extending in a second direction, and a first sub pixel of a pixel in a first row of a first column and a first sub pixel of a pixel in the first row of a second column display different colors.