Pixel Circuit Segmentation for Leakage Current Reduction
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Solution Overview
Problem
In liquid crystal displays, the drain of the TFT may output a leakage current to the data line after being turned off, causing a voltage decrease at the pixel electrode, which affects the deflection of liquid crystal molecules and degrades the image display effect.
Innovation Solution
A pixel circuit with a first charging sub-circuit and a second charging sub-circuit is introduced, where the first charging sub-circuit outputs a data signal to a charging node and the second charging sub-circuit outputs the signal to a display sub-circuit, allowing the charging node to be maintained at a high voltage, reducing the voltage difference and thus minimizing leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single TFT is used to charge the liquid crystal capacitor, then the circuit structure is simple, but leakage current flows from the drain to the data line after the TFT is turned off, causing voltage decrease at the pixel electrode
Solution Approach 1:
The pixel circuit is divided into two separate charging paths: a first charging path with a first TFT and first capacitor, and a second charging path with a second TFT and second capacitor. This segmentation allows independent control of each charging path, enabling the first path to charge quickly while the second path maintains voltage with minimal leakage, thus resolving the contradiction between simple structure and voltage stability.
Solution Approach 2:
The pixel electrode serves as an intermediary element that receives charge from both the first and second capacitors through respective TFTs. The dual-capacitor configuration with the pixel electrode as intermediary allows the system to accumulate charge more efficiently and maintain stable voltage by distributing the charging function across two parallel paths, reducing the impact of leakage from any single TFT.
2Use of energy by moving object
If the TFT is turned off to prevent continuous charging, then energy consumption is reduced, but leakage current still flows from the drain to the data line, affecting liquid crystal deflection
Solution Approach 1:
The first capacitor charges the pixel electrode quickly through the first TFT during the writing phase, establishing the initial voltage. Then the second capacitor takes over to maintain the voltage during the holding phase. This preliminary charging action followed by maintained charging eliminates the need to completely turn off the TFTs, reducing leakage current effects while maintaining energy efficiency.
Solution Approach 2:
The patent changes the operational parameters of the TFTs by using two different TFTs with potentially different characteristics. The first TFT is optimized for fast charging with higher current capability, while the second TFT is optimized for low leakage during voltage maintenance. By changing which TFT is active at different times, the system achieves both energy efficiency and reduced leakage current effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces the influence of leakage current on liquid crystal molecules, ensuring a stable image display by maintaining the voltage of the pixel electrode, thereby enhancing the image display effect.
Implementation Method 1
the first charging sub-circuit is configured to be controllable to output a data signal from the data line to a charging node and to store the data signal from the data line
Implementation Method 2
the second charging sub-circuit is respectively connected to the charging node, the gate line and the display sub-circuit, and is configured to be controllable to output a data signal from the charging node to the display sub-circuit
Implementation Method 3
allowing the charging node to be maintained at a high voltage, reducing the voltage difference and thus minimizing leakage current
Implementation Method 4
the liquid crystal capacitor is used to control deflection of liquid crystal molecules, thereby realizing image display
Data Source
AI summary
The embodiments of the present disclosure disclose a pixel circuit and a driving method thereof, a display substrate, and a display device, the present disclosure belongs to the field of displaying. The pixel circuit includes a gate line, a data line, a first charging sub-circuit, a second charging sub-circuit and a display sub-circuit; the first charging sub-circuit is configured to be controllable to output a data signal from the data line to a charging node and to store the data signal from the data line; and the second charging sub-circuit is respectively connected to the charging node, the gate line and the display sub-circuit, and is configured to be controllable to output a data signal from the charging node to the display sub-circuit.