Transistor Parameter Estimation for Display Brightness Consistency

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Solution Overview

Problem

In systems with transistors having uncertain or varying parameters, existing methods fail to consistently achieve desired brightness across multiple pixels due to parameter differences, leading to inconsistent performance in display devices.

Innovation Solution

A method and system for transistor parameter estimation, which measures current at various control voltages to calculate compensation coefficients, allowing for adjustment of control voltages to match a reference transistor's performance, thereby compensating for parameter variations and ensuring consistent brightness across pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If existing methods are used to drive transistors with uncertain parameters, then the device complexity is reduced, but the brightness consistency across pixels deteriorates

Engineering Contradiction:
Improvecircuit complexityVSAvoidbrightness consistency
Core Design Contradiction:
Device complexityVSIllumination intensity

Solution Approach 1:

The patent applies preliminary action by measuring transistor parameters (threshold voltage, mobility, area) before driving the transistor to display a pixel. Compensation coefficients are calculated in advance based on these measured parameters, allowing the system to pre-adjust control voltages to account for transistor variations before actual display operation, thereby ensuring brightness consistency without adding complex real-time control circuits.

Inventive Principle:
Principle #10Preliminary action

2Illumination intensity

If compensation coefficients are calculated and applied to each transistor, then the brightness consistency is improved, but the device complexity increases

Engineering Contradiction:
Improvebrightness consistencyVSAvoidcircuit complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the electrical parameters (control voltages) based on calculated compensation coefficients derived from measured transistor parameters. Instead of changing the physical structure or adding complex compensation circuits, the system adjusts voltage parameters dynamically to compensate for transistor variations, achieving brightness consistency through parameter optimization rather than structural complexity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If transistor parameters are measured and compensated, then the manufacturing precision is improved, but the measurement precision requirements increase

Engineering Contradiction:
Improvetransistor parameter consistencyVSAvoidparameter measurement accuracy
Core Design Contradiction:
Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent applies feedback by measuring actual transistor parameters (threshold voltage, mobility, area) and using these measurements to calculate compensation coefficients that are then applied to control voltages. This closed-loop feedback mechanism allows the system to automatically adjust for manufacturing variations in transistor parameters, improving manufacturing precision through measurement and compensation rather than requiring extremely tight manufacturing tolerances.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3951761B1System and method for transistor parameter estimation
Publication Date: 2024.05.01 SAMSUNG DISPLAY CO LTD
  • EP3951761B1 patent drawingFigure 1
  • EP3951761B1 patent drawingFigure 2
  • EP3951761B1 patent drawingFigure 3

AI summary

A system and method for setting one or more compensation coefficients for a transistor. In some embodiments, a method for setting a first compensation coefficient for a transistor includes: determining a plurality of measured transistor currents, each at a respective one of a plurality of transistor control voltages; setting the first compensation coefficient based on the measured transistor currents and the transistor control voltages; and adjusting a voltage applied to a gate of the transistor based on the first compensation coefficient, the voltage corresponding to a color value.