Shift Register Alternating Transistors to Reduce Threshold Voltage Drift
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Solution Overview
Problem
Existing gate driver circuits in display technologies face challenges in achieving stable output due to threshold voltage drifts in transistors, leading to unreliable gate scanning signals, particularly when transistors are subjected to bias voltages for extended periods.
Innovation Solution
The proposed solution involves a shift register design with a selection control circuit that alternately controls the operation of first and second transistors using a time-division manner, reducing the probability of threshold voltage drifts by utilizing a combination of pull-up and pull-down control circuits, and incorporating a selection control circuit to manage the bias voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If transistors are subjected to bias voltages for extended periods to maintain gate scanning signals, then the gate driver circuit can operate continuously, but threshold voltage drifts occur leading to unstable output
Solution Approach 1:
The patent applies periodic action by alternately switching between the first transistor and the second transistor in a time-division manner. The selection control circuit periodically selects which transistor conducts, preventing either transistor from being subjected to bias voltage continuously. This periodic switching resolves the contradiction by enabling continuous operation while avoiding threshold voltage drift through regular alternation of the conducting transistor.
2Device complexity
If a single transistor is used to output gate scanning signals, then the circuit structure is simple, but threshold voltage drifts cause unreliable signals
Solution Approach 1:
The patent applies segmentation by dividing the single transistor function into two separate transistors (first transistor and second transistor) that work alternately. The selection control circuit segments the time periods, assigning different transistors to conduct during different time intervals. This segmentation improves signal reliability by preventing threshold voltage drift while maintaining relatively simple circuit structure through the systematic division of functions.
3Ease of operation
If transistors operate continuously without alternation, then the circuit operation is simple, but threshold voltage drifts reduce output stability
Solution Approach 1:
The patent implements periodic action through the selection control circuit that alternately activates the first and second transistors based on time-division multiplexing. This periodic switching maintains operational simplicity by following a regular alternation pattern while simultaneously improving threshold voltage stability by preventing continuous bias application to any single transistor, thus resolving the contradiction between ease of operation and stability.
Data Source
AI summary
A shift register includes a first reset circuit having a first transistor and a second transistor, and a selection control circuit connected to a pull-down node, and control electrodes of the first and second transistors. First electrodes of the first and second transistors are connected to a first voltage terminal, and second electrodes of the first and second transistors are connected to a signal output terminal. The selection control circuit is configured to: control a line between the pull-down node and the control electrode of the first transistor, and a line between the pull-down node and the control electrode of the second transistor to be alternately closed. The first reset circuit is configured to output a voltage of the first voltage terminal to the signal output terminal under control of a potential at the pull-down node transmitted by the selection control circuit.