AMOLED Pixel Aging Compensation via Stress-Specific Correlation Curves

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Solution Overview

Problem

Active matrix organic light emitting device (AMOLED) displays face challenges in accurately compensating for aging due to varying stress conditions, leading to inconsistent luminance and electrical degradation, as existing compensation techniques lack precise characterization correlation curves for different stress levels.

Innovation Solution

A system that extracts pixel parameters, creates stress patterns, and adjusts programming voltages based on measured characteristics to maintain uniformity, using reference pixels under controlled stress conditions to determine and update characterization correlation curves for accurate compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional compensation techniques are used without stress-specific characterization, then the compensation process is simpler, but the accuracy of aging compensation deteriorates due to varying stress conditions

Engineering Contradiction:

Improveaccuracy of aging compensationVSAvoidcomplexity of compensation system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the compensation system by creating separate characterization correlation curves for different stress conditions (e.g., high stress, medium stress, low stress). Each curve is stored in lookup tables and selected based on the current stress level detected from reference pixels, enabling accurate compensation without a single complex universal model

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary characterization of OLED aging behavior under multiple predetermined stress conditions during manufacturing or initialization. These characterization curves are pre-calculated and stored in lookup tables, so that during operation, the system only needs to select the appropriate pre-computed curve based on current stress conditions, avoiding real-time complex calculations

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If a single characterization correlation curve is used for all stress conditions, then the system is simpler to implement, but the compensation accuracy deteriorates because stress conditions vary across pixels

Engineering Contradiction:

Improveadaptability to different stress conditionsVSAvoidnumber of characterization curves

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by tailoring the characterization correlation curve to match the local stress conditions of each pixel. Reference pixels are used to detect local stress levels, and the appropriate pre-stored curve is selected for each pixel based on its specific stress condition, ensuring that compensation is locally optimized rather than uniformly applied

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces dynamics by making the selection of characterization curves adaptive to changing stress conditions. The system continuously monitors reference pixels to detect current stress levels and dynamically selects the most appropriate characterization curve from lookup tables, allowing the compensation system to adapt to varying operational conditions over time

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If reference pixels are used to detect stress conditions in real-time, then the accuracy of stress detection is improved, but the device complexity and power consumption increase

Engineering Contradiction:

Improveprecision of stress condition detectionVSAvoidpower consumption for reference pixels

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by updating the stress condition detection and characterization curve selection at specific intervals (e.g., periodically during operation or at key transition points) rather than continuously. This reduces the power consumption of reference pixels while maintaining sufficient accuracy for compensation

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent uses partial action by employing a limited number of reference pixels (e.g., a small subset of pixels dedicated to stress detection) rather than using all pixels for both display and stress detection. This partial dedication of pixels provides sufficient stress condition information while minimizing the impact on overall power consumption and display performance

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS10089921B2System and methods for extracting correlation curves for an organic light emitting device

Publication Date: 2018.10.02 IGNIS INNOVATION

AI summary

A system for equalizing the pixels in an array of pixels that include semiconductor devices that age differently under different ambient and stress conditions. The system extracts at least one pixel parameter from the array; creates a stress pattern for the array, based on the extracted pixel parameter; stresses the pixels in accordance with the stress pattern; extracts the pixel parameter from the stressed pixels; determines whether the pixel parameter extracted from the stressed pixels is within a preselected range and, when the answer is negative, creates a second stress pattern for the array, based on the pixel parameter extracted from the stressed pixels, stresses the pixels in accordance with the second stress pattern, extracts the pixel parameter from the stressed pixels, and determines whether the pixel parameter extracted from the stressed pixels is within the preselected range.