OLED Pixel Non-Uniformity Extraction via Transform Patterns
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Solution Overview
Problem
Active matrix organic light emitting device (AMOLED) displays face non-uniformity issues due to differential aging of pixels, which affects brightness and color consistency over time, requiring extensive measurements to assess individual pixel status.
Innovation Solution
A method and apparatus for evaluating OLED display pixel status by generating a sequence of patterns using transformations like discrete cosine or wavelet transformations, sensing responses, and deriving a matrix of status values to apply correction signals, allowing for real-time diagnostic tools to improve display uniformity and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each individual pixel is measured to assess display status, then measurement precision is improved, but device complexity and measurement time increase significantly
Solution Approach 1:
The patent segments the measurement process into two levels: global display-level measurements using a small number of sensors, and local pixel-level status extraction through mathematical decomposition. The display is divided into measurable regions that can be characterized by fewer sensors, while individual pixel status is derived computationally without requiring physical sensors at each pixel location.
Solution Approach 2:
The patent introduces mathematical models and algorithms as intermediaries between the physical sensors and the pixel status information. These computational tools translate global measurement data into localized pixel-level diagnostics, eliminating the need for direct one-to-one sensor-pixel mapping and reducing system complexity.
2Measurement precision
If each individual pixel is measured to assess display status, then measurement precision is improved, but loss of time increases due to the large number of measurements required
Solution Approach 1:
The patent applies partial measurement by selecting specific representative regions or patterns for measurement rather than measuring every pixel individually. By measuring a subset of pixels or using reduced measurement patterns, the system achieves sufficient diagnostic accuracy with significantly reduced measurement time and fewer sensors.
3Measurement precision
If extensive measurements are taken to assess pixel status, then measurement precision is improved, but productivity decreases due to the large number of measurements required
Solution Approach 1:
The patent performs preliminary characterization of the display during manufacturing or initial setup, creating reference models and calibration data that enable faster ongoing assessments. This preliminary work establishes baseline parameters that simplify subsequent measurements and reduce the computational burden of continuous monitoring, thereby improving productivity.
Data Source
AI summary
A system and method for deriving a sequence of OLED non-uniformity test patterns. A pattern generator generates a full sequence of display patterns according to a transform function, such as a discrete cosine transformation or wavelet transformation. A driver drives a display with each of the sequence of patterns. A sensor senses a property of the display, such as a total current for the display, for each of the sequence of patterns. An extraction unit derives a pixel non-uniformity model using the sensed properties and an inverse of the transform function. Patterns that contribute less than a threshold amount to the non-uniformity model can be identified and deleted to derive a sparse sequence of patterns, which can be stored in a memory. The sparse sequence of patterns can be used to test the display and extract a set of pixel non-uniformity values. The pixel non-uniformity values can be used to generate a correction signal for the display.