Pixel Transistor Threshold Compensation for Consistent Image Quality
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Solution Overview
Problem
The characteristics of transistors in display device pixels change over time, affecting image quality and necessitating a solution to compensate for these changes.
Innovation Solution
A display device with a driving controller that includes an initial threshold voltage map, delta threshold voltage calculator, weight calculator, and compensator to adjust image signals based on transistor characteristics, using dummy pixels for feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If transistors are operated for a long time, then the display device can maintain continuous operation, but the transistor characteristics change and image quality deteriorates
Solution Approach 1:
The patent measures the initial threshold voltage of transistors before they undergo significant degradation, stores this data, and uses it as a baseline for future compensation calculations. This preliminary measurement enables the system to predict and compensate for threshold voltage changes over time, maintaining image quality during continuous operation
Solution Approach 2:
The patent implements a feedback mechanism where the current threshold voltage is periodically measured and compared with the initial threshold voltage. The difference (delta threshold voltage) is used to calculate compensation values that are applied to the image signals, creating a closed-loop system that automatically corrects for transistor degradation
2Reliability
If compensation for threshold voltage changes is implemented, then image quality is maintained, but device complexity increases
Solution Approach 1:
The patent divides the compensation function into separate modular components: an initial threshold voltage measurement unit, a storage unit for baseline data, a current threshold voltage measurement unit, a calculation unit for determining delta threshold voltage, and a compensation application unit. This segmentation allows each component to perform a specific function independently, making the overall complex system manageable and maintainable
Solution Approach 2:
The patent introduces an intermediary calculation process that computes the delta threshold voltage (difference between initial and current threshold voltages) and uses this intermediate value to determine compensation amounts. This intermediary step simplifies the overall compensation logic by breaking down the complex relationship between threshold voltage changes and required signal adjustments into manageable computational steps
Data Source
AI summary
A display device is disclosed that includes a display panel which includes a pixel, a driving controller which receives an input image signal and outputs an output image signal, and a data driving circuit which provides a data signal corresponding to the output image signal to the pixel. The pixel includes a light emitting device and a first transistor electrically connected to the light emitting device. The driving controller includes an initial threshold voltage map that stores an initial threshold voltage of the first transistor, a delta threshold voltage calculator that calculates a delta threshold voltage of the first transistor over an operating time based on the initial threshold voltage, a weight calculator that calculates a weight based on the initial threshold voltage and the delta threshold voltage, and a compensator that receives the input image signal and outputs an output image signal obtained by compensating for a threshold voltage of the first transistor based on the weight.