Shift Register Unit for Pull-Up Leakage and Transient Current Control
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Solution Overview
Problem
Existing shift register units in AMOLED displays suffer from current leakage at the pull-up node due to floating states, leading to voltage drift and operational failures, and excessive transient currents at the voltage control node due to parasitic capacitors, affecting device performance and yield.
Innovation Solution
Incorporation of a first sensing input leakage prevention circuit and a first current limiting circuit to control the path between the pull-up node and the voltage control node, along with load resistance and capacitance adjustments to manage current flow, reducing transient currents and preventing voltage drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pull-up node is left floating during non-operational states, then the circuit structure is simplified, but current leakage occurs leading to voltage drift and operational failures
Solution Approach 1:
The patent applies preliminary action by proactively controlling the pull-up node voltage before leakage can occur. The sensing input leakage prevention circuit is activated in advance to maintain the pull-up node at a stable valid level voltage during non-operational states, preventing voltage drift before it compromises operational reliability.
Solution Approach 2:
The patent introduces an intermediary component - the sensing input leakage prevention circuit - that mediates between the pull-up node and the rest of the circuit. This intermediary circuit selectively connects or disconnects based on operational state, controlling voltage levels to prevent leakage while maintaining simplicity in the overall circuit design.
2Ease of operation
If parasitic capacitors are present at the voltage control node, then the circuit can function, but excessive transient currents occur affecting device performance and yield
Solution Approach 1:
The patent converts the harmful effect of parasitic capacitors into a beneficial one by using them to store valid level voltage during operational states. The same parasitic capacitance that causes transient current issues is leveraged to maintain voltage levels, and the prevention circuit is designed to work with rather than against these inherent electrical characteristics.
Solution Approach 2:
The patent applies dynamics by making the sensing input leakage prevention circuit state-dependent. The circuit dynamically adjusts its behavior based on the operational state - being active during non-operational states to prevent leakage, and inactive during operational states to allow normal functioning, thereby adapting to different circuit conditions to minimize harmful transient currents.
Data Source
AI summary
The present disclosure provides a shift register unit, including: a first sensing control input circuit and at least one first output circuit; the shift register unit further includes: a first voltage control circuit, a first sensing input leakage prevention circuit and a first current limiting circuit; the first sensing control input circuit is connected to a first pull-up node through the first sensing input leakage prevention circuit, the first sensing control input circuit is connected to the first sensing input leakage prevention circuit at a first sensing input leakage prevention node connected to a first voltage control node, the first sensing input leakage prevention circuit is connected to the clock control signal input terminal and is configured to control on/off between the first sensing input leakage prevention node and the first pull-up node; the first current limiting circuit is connected to the first voltage control node.