AMOLED Display Non-Uniformity Compensation via Optical Extraction
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Solution Overview
Problem
Active matrix organic light emitting diode (AMOLED) displays face non-uniformities due to structural and random variations across the panel, which affect image quality and require additional transistors and lines for monitoring and compensation, leading to decreased pixel density.
Innovation Solution
A system that uses image sensors and optical measurements to extract and quantify structural and low-frequency non-uniformities, modifying input signals to compensate for these variations, thereby interpolating a response curve to create a compensated image, and applying patterns to reduce optical cross-talk and adjust pixel values for uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If monitoring systems are added to measure time dependent parameters for compensation, then image uniformity is improved, but device complexity increases and pixel density decreases
Solution Approach 1:
The patent extracts the compensation function from the pixel circuit itself by using a separate monitoring system that measures time-dependent parameters (such as OLED aging characteristics) and applies compensation through lookup tables and correction algorithms in the driver circuitry. This separates the monitoring and compensation functions from the pixel circuit, avoiding the need for additional transistors within each pixel while still achieving image uniformity compensation.
Solution Approach 2:
The patent implements feedback compensation by measuring the actual output of pixel circuits over time and using this information to adjust subsequent programming. The system measures time-dependent parameters, compares them against reference values, and applies compensation factors from lookup tables to correct for degradation and non-uniformities, creating a closed-loop feedback system that maintains image uniformity without modifying the pixel circuit structure.
2Manufacturing precision
If additional transistors and lines are incorporated for monitoring and compensation, then image uniformity is improved, but pixel density decreases
Solution Approach 1:
The patent extracts the compensation functionality from the pixel circuit level and implements it at the driver circuit level instead. By using separate monitoring systems and applying compensation through lookup tables in the driver circuitry, the patent avoids adding transistors and lines within each pixel, thereby maintaining high pixel density while still achieving image uniformity compensation.
Solution Approach 2:
The patent makes the driver circuitry multi-functional by having it perform both normal display driving functions and compensation functions. The same driver circuitry that controls pixel switching also measures time-dependent parameters, retrieves compensation factors from lookup tables, and applies corrections to the programming signals, eliminating the need for dedicated compensation circuitry within each pixel.
3Reliability
If compensation techniques are applied to account for degradation over time, then display reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the display panel's degradation behavior during manufacturing and storing compensation factors in lookup tables before the product reaches the customer. Time-dependent parameters such as OLED aging characteristics are measured in advance, and compensation algorithms are pre-computed and stored, allowing the system to apply corrections without real-time complex calculations or additional monitoring hardware during product operation.
Solution Approach 2:
The patent changes parameters by measuring time-dependent electrical characteristics (such as threshold voltage shifts and current leakage) and using these parameter changes to index into lookup tables that contain pre-computed compensation factors. The system retrieves appropriate correction values based on the measured parameters and applies them to subsequent programming, providing degradation compensation through parameter-based lookup rather than complex real-time control.
Data Source
AI summary
A system for compensating for non-uniformities in an array of solid state devices in a display panel displays images in the panel, and extracts the outputs of a pattern based on structural non-uniformities of the panel, across the panel, for each area of the structural non-uniformities. Then the structural non-uniformities are quantified, based on the values of the extracted outputs, and input signals to the display panel are modified to compensate for the structural non-uniformities. Random non-uniformities are compensated by extracting low-frequency non-uniformities across the panel by applying patterns, and taking images of the pattern. The area and resolution of the image are adjusted to match the panel by creating values for pixels in the display, and then low-frequency non-uniformities across the panel are compensated, based on the created values.