Shift Register Noise Suppression via Threshold Voltage Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing shift register units in liquid crystal displays face reliability issues due to the pull-down thin film transistors maintaining a high threshold voltage, leading to prolonged activation and eventual inability to suppress noise, affecting the overall performance of the shift register unit.
Innovation Solution
The proposed solution involves a shift register unit configuration with specific thin film transistor connections and threshold voltage management, ensuring that the pull-down transistors can maintain turning on by adjusting the voltages applied to their gate electrodes, thereby guaranteeing their functionality in suppressing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pull-down thin film transistor is used to suppress noise during low level gate drive signal, then the noise suppression capability is improved, but the threshold voltage of the pull-down thin film transistor increases over time causing it to fail turning on
Solution Approach 1:
The patent changes the voltage parameter applied to the gate electrode of the pull-down thin film transistor. Specifically, it applies a second voltage (higher than the first voltage) to the gate electrode when the gate drive signal is at low level, which compensates for the increasing threshold voltage and ensures the transistor remains turned on for effective noise suppression throughout its operational lifetime.
2Reliability
If the pull-down thin film transistor maintains turning on to suppress noise, then the noise suppression performance is maintained, but the threshold voltage offset increases making it unable to turn on
Solution Approach 1:
The patent implements a feedback mechanism where the voltage applied to the gate electrode of the pull-down thin film transistor is dynamically adjusted based on the operational state. The control circuit monitors the threshold voltage offset and compensates by applying appropriate voltage levels, ensuring the transistor maintains proper activation despite threshold voltage drift over time.
3Productivity
If the gate drive signal remains at low level for most time, then the liquid crystal display scan operation is efficient, but the gate drive signal is easily interfered by clock signal producing noise
Solution Approach 1:
The patent converts the harmful clock signal interference into a beneficial effect by using the pull-down thin film transistor to actively suppress the noise. The transistor is specifically designed to counteract the clock signal interference that occurs during the low level period, transforming the noise problem into a controlled suppression mechanism that maintains signal integrity while preserving scan efficiency.
Data Source
AI summary
A shift register unit and a gate drive device for a liquid crystal display are disclosed. Both gate and drain of the tenth thin film transistor are connected to the source of the fifth thin film transistor, a source thereof is connected to a low voltage signal input terminal, threshold voltages of the eighth thin film transistor and the ninth thin film transistor are equal to or less than threshold voltage of the tenth thin film transistor. The shift register unit and the gate drive device for liquid crystal display provided in the present invention, could enable the thin film transistor used to suppress the noise in the shift register unit to maintain turning on, therefore it guarantees the reliability of the shift register unit.