AMOLED Pixel Compensation via Threshold Voltage Fitting
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Solution Overview
Problem
The uneven luminance in AMOLED display devices due to differences in threshold voltage and coefficient of driving thin film transistors between pixels affects the display quality.
Innovation Solution
A method involving a detection device connected to the output terminal of a pixel driving circuit to acquire potential values, fitting driving voltage and current values to determine threshold voltage and coefficient for a reference pixel, and then compensating other pixels based on threshold changes and coefficient ratios to ensure consistent driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional AMOLED pixel drive circuit (2T1C structure) is used, then the device structure is simple and manufacturing is easy, but the threshold voltage and coefficient of driving thin film transistor vary between pixels causing uneven luminance
Solution Approach 1:
The patent applies preliminary action by measuring and storing the actual threshold voltage and coefficient values of each pixel's driving transistor before normal display operation. The detection circuit characterizes each transistor's parameters in advance, and this information is saved for subsequent compensation operations, allowing the system to pre-correct for manufacturing variations.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the driving voltage applied to each pixel based on its measured transistor characteristics. The compensation circuit modifies the voltage parameter individually for each pixel using the stored threshold voltage and coefficient data, thereby compensating for manufacturing variations and achieving uniform luminance across the display.
2Manufacturing precision
If compensation for pixel differences is implemented, then luminance uniformity is improved, but the device complexity and measurement requirements increase
Solution Approach 1:
The patent merges the detection circuit functionality with the existing pixel drive circuit structure. The detection circuit is integrated into the same transistor network, sharing common elements such as the driving transistor, storage capacitor, and signal lines. This integration approach adds compensation capability while minimizing the increase in overall device complexity.
Solution Approach 2:
The patent implements self-service by enabling each pixel to perform its own self-characterization and self-compensation. The detection circuit measures the driving transistor parameters of each pixel individually, and the compensation circuit adjusts each pixel's driving voltage based on its own measured characteristics, without requiring external intervention or complex centralized control.
3Measurement precision
If detection device is connected to acquire potential values, then pixel parameters can be measured accurately, but the operation complexity and time consumption increase
Solution Approach 1:
The patent applies periodic action by implementing the pixel detection and parameter measurement during dedicated detection periods or idle times when the display is not actively showing content. The measurement process is performed periodically or in batches, allowing the system to gather transistor characteristics data without continuously interrupting normal display operation, thus minimizing time loss.
Data Source
AI summary
The present disclosure provides a method of compensating AMOLED pixel difference, including the steps of: fitting the driving voltage value and the driving current value of the reference pixel. Acquiring the threshold voltage, the coefficient and the power value corresponding to the reference pixel according to the fitting result. Acquiring the threshold change of the threshold voltage corresponding to the other pixel relative to the threshold voltage corresponding to the reference pixel and the coefficient ratio of the coefficient corresponding to the other pixel relative to the coefficient corresponding to the reference pixel. Compensating the other pixel difference according to the threshold change, the coefficient ratio and the power value. The disclosure makes the driving current under the same driving voltage be consistent, improves the uniformity of the light-emitting intensity of the AMOLED and enhances the display quality of the AMOLED display device.