EL Display Nonuniformity Compensation via Lookup Table
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Solution Overview
Problem
Electroluminescent displays, particularly OLEDs, suffer from initial nonuniformities due to varying mobilities and threshold voltages of drive transistors and efficiencies of emitters, leading to unacceptable display performance, with existing compensation methods being slow, costly, or limited in signal-to-noise performance.
Innovation Solution
An apparatus providing analog drive transistor control signals to the gate electrodes of EL subpixels using a look-up table to convert nonlinear signals to linear, allowing for simplified compensation of initial nonuniformity without complex pixel circuitry or external measurement devices, capable of raising yield by making initial nonuniformities invisible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If iterative measurement techniques are used to compensate for nonuniformity, then compensation accuracy is improved, but processing time increases significantly
Solution Approach 1:
The patent pre-calculates and stores compensation values in lookup tables during manufacturing or initialization, so that during normal operation, only a single measurement is needed to retrieve the appropriate compensation value. This eliminates iterative measurements and provides instant compensation, resolving the time-accuracy tradeoff by performing the complex computation beforehand.
2Stability of the object's composition
If linear scaling method is used to reduce brightness variations, then uniformity is improved, but dynamic range and brightness are reduced
Solution Approach 1:
The patent applies different compensation values to different pixels or regions based on their specific characteristics stored in lookup tables. Instead of uniformly scaling all pixels, each pixel receives a tailored compensation value that corrects its specific nonuniformity without unnecessarily reducing its brightness, thus maintaining both uniformity and dynamic range.
3Measurement precision
If complete characterization lookup table is used for each pixel, then compensation precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses simple lookup tables that can be implemented in standard memory devices rather than complex real-time computation circuitry. The lookup tables are programmed once during manufacturing and then used repeatedly without degradation, providing high precision compensation through a simple, cost-effective structure that doesn't require expensive or complex hardware.
Data Source
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AI summary
An electroluminescent (EL) panel with 2T1C subpixels is compensated for initial nonuniformity ("mura"). The current of each subpixel is measured at a selected time to provide a status signal representing the characteristics of the subpixel. A compensator receives a linear code value and changes it according to the status signals. A linear source driver drives the panel with the changed code values.