Shift Register Unit Noise Reduction via Pull-Down Drive Module
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Solution Overview
Problem
Existing shift register units in liquid crystal display panels experience significant noise in signal output during non-working times due to parasitic capacitance, which results in coupled noise being outputted with the signal, leading to relatively large noise in the signal output.
Innovation Solution
A shift register unit comprising a pull-up drive module, first and second pull-down drive modules, and an output module, which manages signal levels and connections to reduce noise by disconnecting or connecting the output end with a low-level signal end during non-working times, thereby releasing noise to a low-level signal end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the shift register unit operates with parasitic capacitance between gate and drain of transistor T101, then the leakage current increases and coupled noise is generated, but the structure cannot be changed without adding components
Solution Approach 1:
The patent introduces a first pull-down drive module as an intermediary component connected between the output end and the low-level signal end. This module acts as a mediator to discharge parasitic capacitance and release coupled noise during non-working times, without fundamentally changing the existing circuit structure. The pull-down drive module serves as a dedicated pathway to eliminate harmful noise while preserving the original functional architecture.
2Object-affected harmful factors
If the output end is left floating during non-working time, then the control signal output end outputs high level signal, but noise cannot be eliminated and is outputted with the signal
Solution Approach 1:
The patent extracts the noise discharge function from the main signal path by introducing a separate first pull-down drive module connected to the low-level signal end. This allows the output end to be actively controlled during non-working times rather than left floating. The pull-down drive module creates a dedicated pathway to ground for parasitic capacitance, separating the noise elimination function from the normal signal transmission function.
Solution Approach 2:
The first pull-down drive module performs preliminary action by actively discharging parasitic capacitance during non-working times before the next working cycle begins. This preliminary noise discharge prevents noise from accumulating and being outputted with subsequent signals, ensuring clean signal output from the start of each working cycle.
3Object-affected harmful factors
If transistors T102, T103, and T104 are cut-off during non-working time, then the connection point P is floating, but the voltage at output end cannot be reduced due to parasitic capacitance coupling
Solution Approach 1:
The first pull-down drive module serves as an intermediary discharge path for parasitic capacitance at connection point P. Even though transistors T102, T103, and T104 remain cut-off during non-working times, the pull-down drive module provides a dedicated pathway to ground that allows parasitic capacitance to be discharged, preventing voltage accumulation at the output end while maintaining the original transistor configuration.
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
The solution effectively reduces noise in the signal output of the shift register unit during non-working times by releasing coupled noise to a low-level signal end, improving signal quality during image display.
Implementation Method 1
when the clock signal input end CLKIN is of high potential, it will be coupled to the connection point P through a parasitic capacitance between the gate and the drain of the transistor T101
Data Source
AI summary
The embodiments of the present invention provide a shift register unit, a gate driving device, a display panel and a display device for solving the problem of relatively large noise in the signal outputted by the shift register unit within non-working time when the clock signal is of high level. Within the non-working time of the shift register unit, i.e., when displaying a frame of images, in periods of time other than the period of time when the scan trigger signal is of high level and the period of time when the output end of the shift register unit is of high level, the first pull-down drive module can connect the output end of the shift register unit with a low level signal end when the received clock signal is of high level, or when the received clock signal is of low level and the output end of the shift register unit is of low level, thereby releasing the noise coupled to the output end of the shift register unit by the high level signal to the low level signal end, so as to reduce the noise in the signal outputted by the shift register unit in the non-working time.