Pixel Degradation Compensation Using Local Dummy Pixels
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Solution Overview
Problem
Conventional organic light emitting display devices face challenges in accurately compensating for pixel degradation due to varying current characteristics across different pixel locations, leading to inaccurate luminance measurement and potential visibility of dummy pixels.
Innovation Solution
The display device includes a first pixel with lower than target luminance and a second pixel with higher than target luminance, utilizing a sensor to measure characteristics and a data compensator to calculate and compensate for degradation, using a degradation compensation model to adjust input data based on measured luminance and current differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dummy pixel is used to measure reference current for degradation compensation, then degradation amount can be calculated, but measurement precision decreases as distance between pixel and dummy pixel increases due to location-dependent current variation
Solution Approach 1:
The display panel is divided into multiple sensing regions, each containing both display pixels and dummy pixels. By segmenting the sensing function across multiple local regions rather than using a single remote dummy pixel, the patent ensures that each pixel group has its own nearby reference for accurate degradation measurement, eliminating location-dependent current variation errors.
Solution Approach 2:
Dummy pixels serve as intermediary reference elements that provide a local baseline current measurement for adjacent display pixels. These dummy pixels act as mediators between the power supply network and the display pixels, capturing the same electrical environment variations while providing a stable reference for calculating degradation amounts of neighboring pixels.
2Measurement precision
If a dummy pixel is placed adjacent to the pixel for reference measurement, then measurement accuracy improves, but the dummy pixel becomes visible to the viewer as a non-light-emitting element
Solution Approach 1:
The dummy pixels are configured to emit light with the same color characteristics as the adjacent display pixels. By matching the emission color and intensity of dummy pixels to their neighboring display pixels, the patent makes the dummy pixels imperceptible to viewers while maintaining their function as reference elements for degradation measurement.
Solution Approach 2:
The patent merges the reference measurement function with the light emission function by making dummy pixels emit light identical to adjacent display pixels. This combination eliminates the visual distinction between dummy and display pixels, allowing dummy pixels to serve dual purposes: providing reference current measurements and maintaining visual uniformity across the display panel.
3Manufacturing precision
If pixel degradation is not compensated accurately, then device complexity remains low, but image quality degrades due to luminance differences between degraded and non-degraded pixels
Solution Approach 1:
The patent implements a feedback mechanism where the measured current from dummy pixels is used to calculate degradation amounts, which then generate compensation values applied to adjust the driving currents of display pixels. This closed-loop feedback system continuously monitors and corrects luminance variations, maintaining high manufacturing precision through automated degradation compensation.
Solution Approach 2:
The patent changes the electrical parameters (current and voltage) applied to pixels based on their measured degradation levels. By dynamically adjusting driving currents and voltages according to calculated degradation amounts, the system compensates for pixel aging effects and maintains uniform luminance output across the display panel without requiring physical redesign.
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 improves the accuracy of pixel degradation compensation, preventing image quality degradation by leveraging the higher luminance pixel to compensate for the lower luminance pixel, thus maintaining desired image brightness and preventing the visibility of less degraded pixels.
Implementation Method 1
An organic light emitting display device displays images using organic light emitting diodes
Data Source
AI summary
A display device includes a display panel including a first pixel that emits light with a first luminance that is lower than target luminance and a second pixel that emits light with a second luminance that is higher than the target luminance, a sensor configured to measure a first characteristic of a first light emitting element in the first pixel and a second characteristic of a second light emitting element in the second pixel, and a data compensator configured to calculate a degradation amount of the second pixel based on the first characteristic and the second characteristic.