OLED Sub-pixel Layout for Threshold Voltage Compensation

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Solution Overview

Problem

The complexity of sub-pixel layout in organic light emitting display devices due to compensation transistors increases the size of sub-pixels, reduces resolution, and introduces parasitic capacitance, leading to signal interference and manufacturing cost issues.

Innovation Solution

A simplified sub-pixel layout incorporating an organic light emitting diode, a driving transistor, a first capacitor, a second capacitor, and specific transistors that couple voltages based on programming voltage, reducing the need for additional transistors and lines, thereby compensating threshold voltage deviations and minimizing parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional transistors and lines are added for threshold voltage compensation, then threshold voltage deviation is compensated, but sub-pixel size increases and resolution decreases

Engineering Contradiction:

Improvethreshold voltage compensationVSAvoidsub-pixel size

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

The patent combines the threshold voltage compensation function with the existing driving transistor and capacitor structure. The driving transistor's gate electrode is directly connected to one electrode of the capacitor, merging the compensation circuitry into the existing pixel structure rather than adding separate compensation transistors and lines, thereby maintaining smaller sub-pixel size while achieving threshold voltage compensation.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The capacitor in the patent serves multiple functions: it acts as a storage capacitor to maintain the gate voltage of the driving transistor during the emission period, and simultaneously provides threshold voltage compensation by coupling the gate electrode with the capacitor electrode. This multi-functionality eliminates the need for dedicated compensation components, reducing sub-pixel area.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional transistors and lines are added for threshold voltage compensation, then threshold voltage deviation is compensated, but device complexity increases

Engineering Contradiction:

Improvethreshold voltage compensationVSAvoidsub-pixel circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the compensation function into the existing driving transistor and capacitor structure. The gate electrode of the driving transistor is directly connected to one electrode of the capacitor, eliminating the need for separate compensation transistors and control lines, thereby reducing device complexity while maintaining compensation capability.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If additional transistors and lines are added for threshold voltage compensation, then threshold voltage deviation is compensated, but parasitic capacitance increases causing signal interference

Engineering Contradiction:

Improvethreshold voltage compensationVSAvoidparasitic capacitance and signal interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent combines the compensation function with the existing driving transistor and capacitor, eliminating additional transistors and control lines. This reduction in component count directly decreases parasitic capacitance and minimizes signal interference while maintaining threshold voltage compensation through the direct connection between the gate electrode and capacitor electrode.

Inventive Principle:

Principle #5Merging (Combining)

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 maintains uniform brightness, increases resolution, reduces manufacturing costs, and stabilizes the driving current, effectively compensating for threshold voltage deviations while minimizing signal interference and parasitic capacitance effects.

Implementation Method 1

an organic light emitting diode (OLED), a driving transistor, a first capacitor, a second capacitor, and a first transistor... The brightness of the organic light emitting diode is determined by the amount of the driving current provided to the organic light emitting diode

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10262592B2Sub-pixel of organic light emitting display device and organic light emitting display device including the same

Publication Date: 2019.04.16 LG DISPLAY CO LTD

AI summary

A sub-pixel of an organic light emitting display device comprising an organic light emitting diode connected to a first node; a driving transistor comprising a first electrode, a second electrode connected to the first node, and a gate electrode connected to a second node; a first capacitor connected between the first node and the second node; a second capacitor connected between a programming line and the second node; a first transistor comprising a first electrode connected to the first electrode of the driving transistor, a second electrode connected to the second node, and a gate electrode connected to a scan line; and the first capacitor and the second capacitor are configured to couple the voltage of the first node and the voltage of the second node based on the programming voltage applied to the programming line.