AMOLED Pixel Circuit with Row and Column Sharing Units for Threshold Voltage Compensation
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Solution Overview
Problem
Active Matrix Organic Light Emitting Diode (AMOLED) panels face issues with inconsistent driving currents due to varying threshold voltages of Driving Thin-Film Field Effect Transistors (TFTs), which affect uniformity and are exacerbated by the manufacturing process of Low Temperature Poly-silicon (LTPS) technology, limiting the reduction of pixel size and achieving high Pixels Per Inch (PPI).
Innovation Solution
A pixel circuit design that includes a sub-pixel unit with a driving transistor and sharing units for threshold voltage compensation, where each row and column share a single row and column unit respectively, reducing the number of elements and layout space, and utilizing a 3T1C configuration to achieve threshold voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional threshold voltage compensation circuits are used in each pixel unit, then threshold voltage compensation is achieved, but the number of elements and layout space increase
Solution Approach 1:
The patent merges the threshold voltage compensation function from individual pixel units into shared row and column circuits. The row sharing unit and column sharing unit collectively provide threshold voltage compensation for all pixel units in their respective rows and columns, eliminating the need for dedicated compensation circuits in each pixel unit while maintaining compensation effectiveness.
Solution Approach 2:
The row sharing unit and column sharing unit serve multiple pixel units simultaneously. The row sharing unit compensates for threshold voltages of all pixel units in its row, while the column sharing unit handles the same function for its column, creating a universal compensation mechanism that serves the entire pixel array efficiently.
2Reliability
If traditional threshold voltage compensation circuits are used in each pixel unit, then threshold voltage compensation is achieved, but layout space increases
Solution Approach 1:
The patent merges the threshold voltage compensation function from individual pixel units into shared row and column circuits. The row sharing unit and column sharing unit collectively provide threshold voltage compensation for all pixel units in their respective rows and columns, eliminating the need for dedicated compensation circuits in each pixel unit while maintaining compensation effectiveness.
Solution Approach 2:
The patent transitions from a two-dimensional array of independent pixel units to a three-dimensional circuit architecture where row and column sharing units operate in additional spatial dimensions. This allows the compensation function to be distributed across the array rather than confined within each pixel unit, reducing in-pixel element count.
3Productivity
If pixel size is reduced to achieve high PPI, then pixel density increases, but threshold voltage uniformity deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the row sharing unit and column sharing unit continuously monitor and compensate for threshold voltage variations in pixel units. This feedback loop corrects for manufacturing variations and drift, maintaining uniformity even as pixel size is reduced for high PPI displays.
Solution Approach 2:
The patent dynamically adjusts voltage parameters through the sharing units to compensate for threshold voltage variations. By changing the voltage applied to the light emitting element based on measured threshold voltages, the system maintains consistent luminance output despite manufacturing variations in smaller pixels.
Data Source
AI summary
A pixel circuit and driving method thereof, and a display device can achieve a threshold voltage compensation function, which facilitates reducing the pixel size of AMOLED and achieving high PPI. The pixel circuit comprises a plurality of pixel units arranged in a matrix and each including a sub-pixel unit (b) and a light emitting element (a), the sub-pixel unit (b) including a driving transistor electrically connected with the light emitting element (a), corresponding to each row of pixel units, the pixel circuit further comprises a row sharing unit (c) electrically connected with each pixel unit of the corresponding row via a first connection line; corresponding to each column of pixel units, the pixel circuit further comprises a column sharing unit (d) electrically connected with each pixel unit of the corresponding column via a second connection line; the sub-pixel unit (b), the row sharing unit (c), and the column sharing unit (d) constitute a circuit having a function of compensating for a threshold voltage of the driving transistor in the sub-pixel unit.