Oxide Pixel Circuit Threshold Compensation for Leakage Current
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Solution Overview
Problem
In OLED display panels, variations in threshold voltages of driving transistors due to fabrication processes and temperature changes lead to non-uniform display and inconsistent luminous brightness, while low-temperature polysilicon TFTs exhibit leakage current with a warped-tail phenomenon, making it difficult to lock voltage effectively during each frame.
Innovation Solution
A pixel circuit is designed with a data signal writing module, a driving module, a threshold compensation transistor, a first power voltage writing module, and a light-emitting module, where the threshold compensation transistor, potentially an oxide transistor, compensates the gate voltage of the driving transistor, reducing leakage current and improving voltage locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-temperature polysilicon TFTs are used in pixel circuits, then the display panel can be manufactured with current technology, but leakage current occurs with warped-tail phenomenon making it difficult to lock voltage effectively
Solution Approach 1:
The patent changes the material parameter of the transistor from low-temperature polysilicon to oxide semiconductor, fundamentally altering the electrical characteristics to achieve near-zero leakage current and effective voltage locking throughout the frame period
Solution Approach 2:
The patent introduces a compensation transistor that copies the threshold voltage characteristics of the driving transistor, allowing the system to compensate for threshold variations and maintain stable voltage locking despite manufacturing process differences
2Manufacturing precision
If threshold voltage compensation is implemented, then luminous brightness consistency improves, but device complexity increases due to additional transistors and control signals
Solution Approach 1:
The patent merges the threshold compensation function into the existing pixel circuit structure by using the compensation transistor in parallel with the driving transistor, allowing compensation without requiring completely separate compensation circuits for each pixel
Solution Approach 2:
The compensation transistor serves multiple functions: it compensates for threshold voltage variations, maintains voltage locking during the frame period, and works cooperatively with the driving transistor to ensure stable light emission, reducing the need for additional dedicated compensation components
3Reliability
If oxide transistors are used to reduce leakage current, then voltage locking improves, but manufacturing precision requirements increase
Solution Approach 1:
The oxide semiconductor material inherently provides near-zero leakage current and stable threshold voltage characteristics without requiring complex external compensation mechanisms, allowing the material itself to serve the voltage locking function
Solution Approach 2:
The patent changes the transistor material to oxide semiconductor, which fundamentally alters the electrical parameters to achieve stable threshold voltage and minimal leakage current, reducing sensitivity to typical manufacturing variations
Data Source
AI summary
A pixel circuit, a display panel, a display apparatus and a driving method. The pixel circuit includes a data signal writing module, a driving module, a threshold compensation transistor, a first power voltage writing module and a light-emitting module, wherein the driving module includes a driving transistor.