OLED Pixel Circuit Data Voltage Compensation for Brightness Uniformity
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Solution Overview
Problem
Conventional compensation algorithms for OLED displays are inadequate in compensating data voltage for individual subpixels, limiting their ability to enhance display image uniformity due to threshold voltage drift in driving transistors.
Innovation Solution
A method and apparatus for compensating data voltages in OLED displays by applying testing and setting voltages to determine monitoring voltages, allowing for individual compensation of data voltages based on threshold voltage variations, which are used to adjust the data voltage applied to each pixel circuit, improving image uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional compensation algorithms are used, then the pixel circuit structure is simplified and fabrication is easier, but the data voltage compensation for individual subpixels is insufficient, limiting display image uniformity
Solution Approach 1:
The patent divides the display panel into multiple pixel circuits, each corresponding to a subpixel (red, green, blue). Each pixel circuit independently measures its own driving transistor parameters (threshold voltage, mobility) and applies individualized compensation. This segmentation enables precise per-pixel compensation while maintaining overall system simplicity, resolving the contradiction between manufacturing ease and display uniformity.
Solution Approach 2:
The patent implements feedback mechanisms where sensing transistors measure the actual electrical parameters (threshold voltage, mobility) of driving transistors in each pixel circuit. These measured values are fed back to compensation circuits that adjust data voltages accordingly. This closed-loop feedback ensures accurate compensation for individual subpixels without complicating the overall manufacturing process.
2Device complexity
If threshold voltage drift is not compensated, then the device complexity is reduced, but the brightness uniformity of display image deteriorates
Solution Approach 1:
Each pixel circuit contains sensing transistors and compensation circuits that automatically measure and compensate for threshold voltage drift in its own driving transistor. This self-service mechanism operates without external intervention, continuously maintaining brightness uniformity while adding minimal complexity to each pixel. The local self-compensation approach avoids the need for complex external compensation systems.
3Manufacturing precision
If individual subpixel compensation is implemented, then display image uniformity is improved, but the measurement and compensation time increases
Solution Approach 1:
The patent implements periodic compensation cycles where sensing transistors measure driving transistor parameters at specific intervals (e.g., at the beginning of each frame or at predetermined time points). This periodic measurement approach balances the need for accurate individual subpixel compensation with the constraint of limited time, ensuring display uniformity without excessive time loss.
Solution Approach 2:
The patent performs threshold voltage and mobility measurements in advance during dedicated measurement periods before normal display operation. Compensation voltages are calculated and stored beforehand, then applied during display refresh cycles. This preliminary action ensures accurate compensation is ready before needed, reducing real-time compensation time while maintaining high display uniformity.
Data Source
AI summary
The present application discloses a method for compensating data voltages in a display apparatus. The method for individually compensating a data voltage to be applied to one of the multiple pixel circuits in the display apparatus. The method includes obtaining a threshold voltage of the driving transistor in the one of the multiple pixel circuits. Additionally, the method includes applying a testing voltage to a gate electrode of the driving transistor for charging the sense line up to a first time period to determine a first monitoring voltage associated with the sense line. The testing voltage is set to be a sum of the threshold voltage and a first setting voltage. Moreover, the method includes compensating a data voltage to be applied to the one of the multiple pixel circuits based on the first monitoring voltage and the threshold voltage.