OLED Display Device Brightness Compensation for Lifespan

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Solution Overview

Problem

Organic light emitting diode (OLED) display devices face issues with brightness deterioration and color temperature shifts due to uneven stress on color emission layers, leading to residual images and image stitching, and existing compensation methods either increase power consumption or reduce lifespan.

Innovation Solution

An OLED display device with a data transform portion that sets compensation brightness gains based on deterioration information, using time-rated target brightness values and color temperature compensation to maintain initial brightness and color temperature, preventing overcompensation and lifespan reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If bottom-up compensation method is used to increase brightness of each pixel in proportion to stress degree, then brightness uniformity is improved, but power consumption increases and stress on pixels is weighted

Engineering Contradiction:
Improvebrightness uniformityVSAvoidpower consumption
Core Design Contradiction:
Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by introducing time-rated target brightness values that vary based on display period and compensation brightness gain. Instead of uniformly increasing brightness across all pixels (bottom-up method), the system dynamically adjusts target brightness values according to individual pixel deterioration levels and elapsed time, thereby maintaining brightness uniformity without proportionally increasing power consumption for all pixels.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by pre-calculating and storing time-rated target brightness values in a lookup table before actual display operation. The data transform portion retrieves appropriate target values based on current display period and compensation gain, allowing the system to proactively compensate for OLED deterioration without real-time complex calculations, thus reducing power consumption while maintaining brightness uniformity.

Inventive Principle:
Principle #10Preliminary action

2Use of energy by moving object

If top-down compensation method is used to decrease brightness from greatest stress pixel, then power consumption is reduced, but brightness falls below desired specification and lifespan is reduced

Engineering Contradiction:
Improvepower consumptionVSAvoidbrightness specification
Core Design Contradiction:
Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The patent applies local quality by treating each pixel individually with its own target brightness value based on specific deterioration characteristics and display period. Instead of uniformly decreasing brightness across the entire display (top-down method), the system selectively adjusts target brightness values for different pixels according to their local deterioration states, ensuring that brightness specifications are met in each region while optimizing power consumption locally rather than globally.

Inventive Principle:
Principle #3Local quality

3Temperature

If CCT compensation method is used to increase brightness of blue organic emission layer, then color temperature is maintained, but blue layer is exposed to more serious stress and deterioration is accelerated

Engineering Contradiction:
Improvecolor temperatureVSAvoidlifespan of blue emission layer
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent applies dynamics by making the target brightness value adaptive and time-dependent rather than static. The time-rated target brightness values change based on display period and compensation brightness gain, allowing the system to dynamically adjust compensation strategies. For blue emission layers, this means the target values are modulated according to elapsed time and measured deterioration, maintaining color temperature while avoiding excessive stress that would accelerate degradation.

Inventive Principle:
Principle #15Dynamics

4Illumination intensity

If compensation is performed to maintain initial brightness, then image quality is maintained, but stress on deteriorated OLED is increased leading to further deterioration

Engineering Contradiction:
ImprovebrightnessVSAvoidstress on OLED
Core Design Contradiction:
Illumination intensityVSStress or pressure

Solution Approach 1:

The patent applies partial or excessive action by using time-rated target brightness values that provide controlled compensation rather than full compensation to initial brightness. The compensation brightness gain and display period parameters allow the system to apply partial compensation that is sufficient to maintain acceptable image quality while avoiding excessive stress that would occur with full compensation to original brightness levels.

Inventive Principle:
Principle #16Partial or excessive action

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

The solution effectively maintains high brightness and color temperature, minimizing stress on pixels and preventing non-controllable states, ensuring consistent image quality despite pixel deterioration.

Implementation Method 1

The current passing through the drain and source electrodes of the driving transistor is applied to an organic light emitting diode and allows the organic light emitting diode to emit light.

Methodology Applied
Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP3040972B1Organic light emitting diode display device
Publication Date: 2020.02.05 LG DISPLAY CO LTD
  • EP3040972B1 patent drawingFigure 1~3
  • EP3040972B1 patent drawingFigure 4~5
  • EP3040972B1 patent drawingFigure 6

AI summary

An organic light emitting diode display device is disclosed which adjusts brightnesses and color temperatures of RGBW data signals and matches the brightnesses of organic light emitting diodes and the color temperature of a white organic light emitting diode with the target brightness value and the target color temperature of a white pixel. As such, an overcompensation and the reduction of a lifespan can be prevented. Also, relatively high brightness and color temperature can be maintained.