Shift Register Noise Removal Module for Flat-Panel Displays
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Solution Overview
Problem
Existing shift register units in flat-panel displays produce waveforms with noise due to parasitic capacitance and leakage currents, resulting in defective display pictures.
Innovation Solution
Incorporating a noise removal module that holds signals above a preset threshold and outputs them at a second terminal when a noise removal control signal exceeds another threshold, ensuring a stable signal is sent to gate lines, thereby reducing noise in the output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large-sized transistor (channel width 9000um) is used in the pull-up module, then the driving capability is improved, but parasitic capacitance increases significantly
Solution Approach 1:
The pull-up module is divided into two separate transistors (M3 and M4) working in a push-pull configuration. This segmentation allows each transistor to have a smaller channel width (4500um each) compared to the original single large transistor (9000um), thereby reducing the parasitic capacitance while maintaining the same driving capability through coordinated operation of both transistors.
2Speed
If the transistor is turned on or off rapidly, then the switching speed is improved, but leakage current and noise are generated
Solution Approach 1:
A noise removal module comprising capacitor C2 and transistors M7-M10 is added to the circuit. This module acts as a buffer that filters out noise and leakage currents from the output signal before it reaches the gate line. The capacitor C2 holds the signal temporarily, and the transistors M7-M10 control the signal passage, thereby cushioning the harmful effects of rapid switching while maintaining switching speed.
3Productivity
If the first capacitor C1 is used for signal coupling, then the signal transmission is improved, but noise is coupled to the output terminal
Solution Approach 1:
The noise removal module acts as an intermediary between the pull-up module and the output terminal. Capacitor C2 in the noise removal module works as a secondary coupling element that filters the signal from C1, removing noise components while preserving the useful signal. This intermediary structure allows signal transmission to continue while blocking the harmful noise coupling.
Data Source
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AI summary
Provided are a shift register unit, a gate driver and a display device. The shift register unit comprises: a pull-up control module, a pull-up module, a reset module, and a denoise module for holding a signal output from the first output terminal when the signal has a level higher than a first preset threshold and outputting the held signal from a second output terminal when a signal output from a denoise control signal output terminal has a level higher than a second preset threshold. The signal output from the first output terminal is filtered by using the signal output from the first output terminal and the signal output from the denoise control signal output terminal, and thus burrs in the signal output from the first output terminal are eliminated, that is, noise is eliminated, solving the problem that a defective display picture due to the noise in the output signal.