Shift Register Unit Pull-Up Node Noise Reduction

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Solution Overview

Problem

In AMOLED display panels, the first pull-up node remains in a floating state for a long period during the pixel sensing phase, leading to serious noise interference and affecting the stability of the output pulse from the driving output circuit.

Innovation Solution

A shift register unit is designed with a sensing control circuit, a first sensing input circuit, a first display input circuit, a first switch circuit, and a first driving output circuit, which control the connection and disconnection between the first pull-up node and the first pull-up back node in response to signals from the switch signal input terminal, ensuring the active level signal is written to the first pull-up back node during the pixel sensing phase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the first pull-up node remains in a floating state during the pixel sensing phase, then the circuit structure is simple, but noise interference increases and output pulse stability deteriorates

Engineering Contradiction:

Improvecircuit structureVSAvoidoutput pulse stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces a first pull-up back node as an intermediary element between the first pull-up node and the driving output circuit. This intermediary node allows the first pull-up node to remain floating during the sensing phase while still providing a stable reference voltage to the driving output circuit through the switch circuit, thereby resolving the contradiction between circuit simplicity and output stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs dynamic control of the switch circuit to change the connection state between the first pull-up node and first pull-up back node based on the operating phase. During the display phase, the switch connects the two nodes; during the sensing phase, the switch disconnects them, allowing the first pull-up node to float while maintaining stability at the first pull-up back node. This dynamic switching resolves the contradiction by adapting the circuit configuration to different operational requirements.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the first pull-up node is kept floating during pixel sensing, then the circuit operation is straightforward, but noise interference at the first pull-up back node increases

Engineering Contradiction:

Improvecircuit operationVSAvoidnoise interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent segments the voltage supply function by introducing a separate first pull-up back node that is distinct from the first pull-up node. This segmentation allows the first pull-up node to float during sensing (maintaining ease of operation) while the first pull-up back node maintains a stable voltage level (reducing noise interference). The switch circuit controls the connection between these segmented nodes based on operational phase.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first pull-up back node acts as an intermediary that isolates the driving output circuit from the floating first pull-up node during the sensing phase. This intermediary structure allows the circuit to operate simply with the floating node while preventing noise from propagating to the output circuit, thus resolving the contradiction between ease of operation and noise reduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a switch circuit is added to control connection between first pull-up node and first pull-up back node, then noise interference is reduced and output stability is improved, but device complexity increases

Engineering Contradiction:

Improveoutput pulse stabilityVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The switch circuit in the patent is designed to perform multiple functions: during the display phase, it connects the first pull-up node to the first pull-up back node to provide stable voltage; during the sensing phase, it disconnects them to allow the first pull-up node to float while maintaining stability at the back node. This multi-functionality justifies the added complexity by providing both noise reduction and stability improvement with a single circuit element.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12266409B2Shift register unit, gate driving circuit and gate driving method

Publication Date: 2025.04.01 HEFEI BOE ZHUOYIN TECH CO LTD

AI summary

The disclosure provides a shift register unit, including: a sensing control circuit configured to write an active level signal to a sensing control node; a first sensing input circuit connected to a first pull-up back node and configured to write an active level signal to the first pull-up back node; a first display input circuit connected to a first pull-up node and configured to write an active level signal to the first pull-up node; a first switch circuit connected in series between the first pull-up node and the first pull-up back node and configured to control connection and disconnection between the first pull-up node and the first pull-up back node in response to control of a signal from a switch signal input terminal; and a first driving output circuit connected to the first pull-up back node and configured to write a signal to a first driving signal output terminal.