AMOLED Pixel Calibration Using Digital Reference Values

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Solution Overview

Problem

Modern display technologies, such as AMOLED, suffer from defects, variations, and non-uniformities from fabrication, leading to image inaccuracies and deviations over their operational lifetime, necessitating effective image calibration and compensation methods to produce accurate and uniform images.

Innovation Solution

The method involves integrating pixel current outputs with reference signals to generate comparison values, adjusting pixel inputs based on these comparisons, using integrators, comparators, and data processing units to control integration and sampling times, and adjust inputs to match expected current magnitudes, thereby compensating for operating inaccuracies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional pixel calibration methods are used, then reference current generation is simple, but measurement precision and compensation accuracy deteriorate due to fabrication defects and aging variations

Engineering Contradiction:

Improvepixel output measurement accuracyVSAvoidreference current generation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a digital reference value that copies the expected pixel output characteristics instead of generating physical reference currents. This digital copy approach maintains measurement precision while eliminating the complexity of precise reference current generation hardware

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical/electrical reference current generation system with a digital processing system. The comparator digitizer converts pixel outputs to digital values and compares them with digital reference values, substituting physical current generation with digital computation to improve precision without hardware complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If longer integration times are used for pixel current measurement, then measurement precision improves, but productivity decreases due to slower compensation cycles

Engineering Contradiction:

Improvepixel current integration accuracyVSAvoidimage compensation speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent implements periodic sampling and compensation cycles where pixel outputs are measured at specific intervals rather than continuously. This periodic action maintains measurement precision at sampling moments while enabling faster overall compensation cycles compared to continuous long integration approaches

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent dynamically adjusts integration and sampling times based on pixel type and expected output magnitudes. By making integration times adaptive rather than fixed, the system optimizes precision for each measurement while maintaining high productivity through shorter average integration periods

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If separate reference current sources are used for different pixel types, then adaptability improves, but device complexity increases due to multiple current generation circuits

Engineering Contradiction:

Improvesupport for multiple pixel typesVSAvoidreference current source configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent uses a single digital reference value storage system that serves all pixel types universally. The data processing unit stores different reference values in memory and retrieves the appropriate one based on pixel type identification, eliminating the need for multiple separate reference current sources while maintaining full adaptability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces a digital reference value and data processing unit as an intermediary between the comparator and pixel outputs. This intermediary layer handles the adaptation to different pixel types through digital logic and memory, replacing complex multi-circuit reference current generation with a single universal digital reference system

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of operation

If analog reference values are stored in capacitors, then ease of operation improves for simple comparisons, but manufacturing precision deteriorates due to capacitor variation and leakage

Engineering Contradiction:

Improvereference value storage simplicityVSAvoidcapacitor value consistency

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent replaces the analog capacitor-based reference storage system with a digital memory-based system. Digital reference values are stored in memory cells that do not suffer from capacitor leakage or variation, eliminating manufacturing precision issues while maintaining ease of operation through simple digital readout and comparison

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11501705B2Systems and methods of pixel calibration based on improved reference values

Publication Date: 2022.11.15 IGNIS INNOVATION

AI summary

What is disclosed are systems and methods of compensation of images produced by active matrix light emitting diode device (AMOLED) and other emissive displays. The electrical output of a pixel is compared with a reference value to adjust an input for the pixel. In some embodiments an integrator is used to integrate a pixel current and a reference current using controlled integration times to generate values for comparison.