Organic EL Display Pixel Luminance Uniformity Correction
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Solution Overview
Problem
Organic EL display devices face luminance differences at pixel region boundaries due to variations in light emission current efficiency, leading to image quality deterioration, especially when displaying patterns like checkerboards or web content over time.
Innovation Solution
A current drive-type display device with a correction calculation unit that measures current through the drive TFT, calculates light emission current efficiency for each pixel, and adjusts the video signal based on a two-dimensional distribution of this efficiency to compensate for differences between neighboring pixels, ensuring consistent luminance across regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If current measurement and correction is implemented, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The display device performs self-diagnosis and self-correction by measuring its own current characteristics and automatically adjusting video signals to compensate for luminance variations, eliminating the need for external calibration equipment
Solution Approach 2:
The system measures and corrects based on electrical current parameters rather than directly measuring optical output, simplifying the correction mechanism while achieving luminance uniformity through current-based compensation
2Manufacturing precision
If periodic current measurement is performed, then image quality is improved, but loss of time increases
Solution Approach 1:
The system performs current measurements and updates correction values during idle periods or at the beginning of operation, preparing correction data in advance so that actual display operation can proceed without time loss
Solution Approach 2:
The correction values are updated periodically rather than continuously, measuring current characteristics at intervals and applying corrections during these periods while maintaining normal display operation at other times
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 reduces luminance differences at pixel region boundaries, enhancing image quality by compensating for variations in light emission current efficiency, thereby maintaining consistent display performance over time.
Implementation Method 1
The organic EL element emits light at luminance in accordance with an amount of a current passing therethrough
Data Source
AI summary
An initial current ratio calculation unit obtains an initial current ratio for each pixel based on a current measurement result by a data line drive/current measurement circuit. A light emission current efficiency calculation unit obtains a light emission current efficiency for each pixel referring to an LUT, based on a measured operating temperature and the initial current ratio. A first correction unit corrects a video signal for each pixel in view of characteristics of each pixel, based on the current measurement result and the light emission current efficiency. A second correction unit obtains a correction term for each pixel in view of a difference in the light emission current efficiency compared to neighboring pixels, based on a two-dimensional distribution of the light emission current efficiency. The correction term obtained by the second correction unit is added to the video signal corrected to obtain a corrected video signal.