3T2C Pixel Driving Circuit for IGZO High-Frequency Charging
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Solution Overview
Problem
Traditional display panel backplane technologies, such as amorphous silicon, low temperature polysilicon, and indium gallium zinc oxide, fail to meet the requirements of dynamic frame rate technology due to monistic performance advantages, particularly in achieving high charging current for IGZO transistors at high frequencies without compromising stability or increasing power consumption.
Innovation Solution
A 3T2C pixel driving circuit structure is introduced, utilizing a first transistor, a second transistor, a third transistor, a first capacitor, a second capacitor, a storage capacitor, and a liquid crystal capacitor, operating in pre-charge, boost, transition, and holding phases to raise the electrical potential of a node to a level greater than the high electrical potential of the gate output signal, enhancing the charging ability of IGZO transistors while maintaining circuit stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current of IGZO is increased by increasing the aspect ratio of TFT, then the charging ability is improved, but the TFT size increases and occupies too much space, resulting in reduced aperture ratio
Solution Approach 1:
The patent changes the gate-source voltage parameter by introducing a bootstrap transistor that dynamically adjusts the gate voltage of the driving transistor. This allows achieving higher charging current without increasing the physical size of the TFT, thus maintaining the aperture ratio while improving charging ability.
2Productivity
If the gate-source voltage difference Vgs of all TFTs is increased to increase charging current, then the charging ability is improved, but the stress on TFTs increases and they become prone to aging, affecting overall driving circuit stability
Solution Approach 1:
The patent applies different voltage strategies to different parts of the circuit. The bootstrap transistor locally increases the gate-source voltage only for the driving transistor during the charging phase, while other TFTs operate under normal voltage conditions. This localized approach improves charging ability without subjecting all TFTs to high stress that would cause aging.
3Productivity
If LTPS technology is used to achieve higher mobility and better charging capacity, then the charging ability is improved, but the leakage current increases and picture holding ability deteriorates
Solution Approach 1:
The patent dynamically changes the operating parameters of the IGZO transistor by using a bootstrap transistor to increase the gate-source voltage during the charging phase. This allows IGZO to achieve LTPS-level charging capacity without the high leakage current problem, as the enhanced charging is achieved through voltage modulation rather than material substitution.
4Loss of energy
If IGZO technology is used to achieve lower leakage current and better picture holding ability, then the power consumption is reduced, but the charging capacity decreases and insufficient charging electrical potential occurs at high frequencies
Solution Approach 1:
The patent introduces a bootstrap transistor as an intermediary component that mediates between the data line and the gate of the driving transistor. This intermediary actively boosts the gate voltage during the charging phase, enabling IGZO to achieve sufficient charging electrical potential at high frequencies while maintaining its inherent low leakage current and power consumption advantages during the holding phase.
Data Source
AI summary
The present disclosure provides a pixel driving circuit and a display panel. After pre-charging a first node to a first electrical potential, raising it to a second electrical potential through a first capacitor by a current row gate output signal G(n), and then raising it to a third electrical potential which is a high electrical potential greater than an electrical potential of the current row gate output signal G(n), so that a first transistor is turned on and data is written, raising an original electrical potential of a gate and improving driving capability since a gate electrical potential of the first transistor can be raised to greater than the G(n).