Shift Register Node Sustaining Circuit for Output Stability
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Solution Overview
Problem
The potentials of pull-up and pull-down nodes in shift registers used in GOA circuits fluctuate due to electrical coupling, channel resistances, and off currents, leading to unstable output and display anomalies.
Innovation Solution
A node sustaining circuit is introduced, comprising sustainment control sub-circuits and transistors with varying aspect ratios, which sustain the potential of control nodes by outputting high or low level voltages under the control of a voltage sustaining node, ensuring stable output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistors and capacitors are used to control potentials of pull-up and pull-down nodes in shift register, then the GOA circuit can perform progressive scan, but the potentials fluctuate due to electrical coupling, channel resistances and off currents causing unstable output
Solution Approach 1:
A node sustaining circuit is introduced as an intermediary component between the existing shift register circuit and the output. This circuit includes a sustaining transistor connected to the pull-up node and a sustaining capacitor, which acts as a mediator to buffer and stabilize the potential at the pull-up node, preventing fluctuations from propagating to the output. The sustaining circuit isolates the output from the harmful effects of electrical coupling, channel resistances, and off currents in the main shift register transistors.
2Ease of manufacture
If electrical coupling and channel resistances are present in shift register, then the circuit can operate with standard transistor components, but the off current causes potential fluctuation and unstable output
Solution Approach 1:
A sustaining capacitor is connected to the pull-up node to provide beforehand cushioning against potential fluctuations. The capacitor is pre-charged to the appropriate voltage level and acts as a local energy reservoir that compensates for voltage drops caused by off currents and channel resistances. This prior cushioning ensures that even when transistors are in the off state or have high channel resistance, the potential at the pull-up node remains stable, preventing output instability without requiring changes to the standard transistor components.
Data Source
AI summary
A shift register, a gate driving circuit, a display device, and a driving method of a node sustaining circuit are disclosed. The shift register includes an input sub-circuit, a reset sub-circuit, an output sub-circuit, a pull-down sub-circuit, a first control sub-circuit, a second control sub-circuit, a first storage sub-circuit, and a node sustaining circuit. The node sustaining circuit is configured to sustain the potential of a node, which is one of a pull-up node or a pull-down node in the shift register.