Two-Stack OLED Subpixel with Auxiliary Electrode for Power Reduction

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Solution Overview

Problem

Organic light emitting display devices face high power consumption issues, particularly in ultra-high resolution applications like head-mounted displays, due to the complexity of their stack structure and the challenges of applying deposition masks over large areas.

Innovation Solution

A display device design featuring a substrate with a first subpixel, a first electrode, two organic light emitting layers, and an auxiliary electrode connected to a second electrode, allowing light emission in a one-stack voltage configuration even with a two-stack structure, thereby reducing overall power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a two-stack structure is used to form red, green and blue pixels with a white light emitting layer, then the manufacturing area can be enlarged, but the power consumption increases

Engineering Contradiction:

Improvemanufacturing areaVSAvoidpower consumption

Core Design Contradiction:

Area of stationary objectVSUse of energy by moving object

Solution Approach 1:

The patent divides the two-stack structure into separate functional layers: a first organic light emitting layer for white light emission and a second organic light emitting layer for color filtering. By segmenting the light emission function from the color generation function, the device can operate the first layer with lower voltage while the second layer enhances color purity, thereby reducing overall power consumption while maintaining large-area manufacturing capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using the conventional approach where each stack independently generates its full color spectrum, the patent inverts the approach by having the first layer emit white light and the second layer selectively filter/emit specific colors. This inversion allows the first layer to operate at lower power while the second layer provides color differentiation, resolving the power consumption issue in large-area displays

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If FMM technology is used to form organic light emitting layers, then small-to-medium panels can be manufactured, but large area application is difficult due to mask drooping

Engineering Contradiction:

Improvepattern formation precisionVSAvoidpanel area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent extracts the color filtering function into a separate second organic light emitting layer, allowing the first layer to be formed using conventional FMM technology for precise pattern formation in small-to-medium panels. The second layer is then formed to cover the entire display area without requiring precise patterning, thus eliminating mask drooping issues while maintaining manufacturing precision for the critical pixel structures

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If a two-stack structure is used for ultra-high resolution displays, then color accuracy can be improved, but power consumption becomes excessively high

Engineering Contradiction:

Improvecolor accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by concentrating the color accuracy enhancement function in the second organic light emitting layer, which is selectively positioned only where color differentiation is needed. The first layer provides uniform white light emission across the entire display, while the second layer locally enhances color accuracy in specific pixel regions, thereby achieving high color accuracy without proportionally increasing power consumption across the whole display

Inventive Principle:

Principle #3Local quality

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 configuration enables reduced power consumption while maintaining efficient light emission, simplifying manufacturing and improving the yield of organic light emitting display devices, especially in high-resolution applications.

Implementation Method 1

an organic light emitting layer including first and second organic light emitting layers arranged on the first sub electrode... the organic light emitting layer provided in the first subpixel can emit light in accordance with a voltage

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11276742B2Display device

Publication Date: 2022.03.15 LG DISPLAY CO LTD

AI summary

A display device can include a substrate provided with a first subpixel, a first electrode including a first sub electrode provided on the first subpixel, an organic light emitting layer including first and second organic light emitting layers arranged on the first sub electrode and a second organic light emitting layer arranged on the second sub electrode, a second electrode arranged on the organic light emitting layer, and an auxiliary electrode arranged between the first organic light emitting layer on the first sub electrode and the second organic light emitting layer on the first sub electrode, wherein the auxiliary electrode is connected with the second electrode. Therefore, although the first subpixel has a two-stack structure, the organic light emitting layer can emit light in accordance with a voltage of one-stack, whereby overall power consumption can be reduced.