7T2C Pixel Driving Circuit for Low-Frequency OLED Power Reduction
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Solution Overview
Problem
Existing OLED display panels face issues with high power consumption and flicker due to large leakage currents in thin film transistors formed by the low temperature poly-silicon process, particularly during low-frequency displays, which affect display quality.
Innovation Solution
A display panel with a seven transistors and two capacitors (7T2C) circuit structure is introduced, featuring a stack of semiconductor and metal layers with oxide semiconductor transistors and capacitors, which reduces power consumption and stabilizes display effects by optimizing the connection and configuration of transistors and capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thin film transistors are formed by low temperature poly-silicon process, then manufacturing cost is reduced and ease of manufacture is improved, but leakage current increases leading to high power consumption and flicker
Solution Approach 1:
The patent introduces a dual-capacitor circuit configuration (first capacitor connected to gate of switching transistor, second capacitor connected to gate of driving transistor) to store charge and compensate for leakage effects. This circuit parameter change allows the use of LTPS transistors while mitigating their high leakage current, thus maintaining ease of manufacture while reducing power consumption and flicker during low-frequency display operation.
2Device complexity
If thin film transistors are formed by low temperature poly-silicon process, then manufacturing complexity is reduced, but display quality deteriorates due to flicker and high power consumption
Solution Approach 1:
The patent uses capacitors as intermediary elements to store electrical charge and compensate for the high leakage current of LTPS transistors. The first capacitor stores charge for the switching transistor gate, while the second capacitor stores charge for the driving transistor gate, thereby maintaining stable voltage levels and improving display quality without increasing transistor fabrication complexity.
3Use of energy by moving object
If leakage current of thin film transistors is reduced, then power consumption decreases, but this requires advanced transistor processes increasing manufacturing difficulty
Solution Approach 1:
The patent segments the charge storage function into two separate capacitors rather than using a single capacitor or relying solely on transistor process improvements. The first capacitor handles charge storage for the switching transistor, while the second capacitor handles charge storage for the driving transistor, allowing the use of simpler LTPS processes while achieving lower effective power consumption through circuit-level compensation.
Data Source
AI summary
The present application provides a display panel. The display panel includes a substrate; and a pixel driving circuit layer including a plurality of pixel driving circuits, wherein each of the pixel driving circuits includes a first capacitor and a second capacitor that are arranged on a same metal layer, so as to achieve low-frequency display, and meanwhile reduce power consumption of the pixel driving circuits.