GOA Scanning Driver Leakage Reduction via Segmented Pull-Up Control
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Solution Overview
Problem
Conventional gate driver on array (GOA) circuits in LCDs suffer from high current leakage and reliability issues due to voltage threshold changes at high temperatures, affecting the scanning driver's performance.
Innovation Solution
The proposed solution involves a scanning driver with cascaded scanning circuits, including a pull-up control module with multiple transistors, a driving module, a pull-down module, and a constant low voltage supply, which generates and maintains a stable scan voltage level signal, preventing current leakage and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single transistor is used in the pull-up control module, then the device complexity is reduced, but current leakage increases and reliability deteriorates at high temperatures
Solution Approach 1:
The pull-up control module is segmented into three transistors (first, second, and third transistors) with distinct functions: the first transistor receives the scanning signal, the second transistor controls the scan voltage level signal, and the third transistor prevents current leakage by isolating the constant high voltage supply. This segmentation resolves the contradiction by improving reliability through functional distribution while maintaining reasonable device complexity.
2Temperature
If the threshold voltage becomes negative at high temperature, then the transistor operation is affected, but current leakage increases
Solution Approach 1:
The third transistor is configured to preemptively prevent current leakage before it can occur by controlling the connection between the constant high voltage level supply and the second transistor's input terminal. This preliminary anti-action counteracts the harmful effect of negative threshold voltage at high temperatures, maintaining reliability without requiring temperature compensation circuits.
3Device complexity
If input signal variation has big influence on output signal, then the circuit is simpler, but reliability of scanning driver deteriorates
Solution Approach 1:
The second transistor serves as an intermediary between the first transistor's output and the scan voltage level signal. It isolates the output from input signal variations, ensuring that changes in the scanning signal do not directly affect the scan voltage level. This intermediary approach improves reliability by decoupling input variations from output stability while maintaining a relatively simple control mechanism.
Data Source
AI summary
The present disclosure proposes a scanning driver for driving scan lines row by row. The scanning driver includes cascaded scanning circuits. Each scanning circuit includes a pull-up control module, a driving module, a pull-down module, a pull-down holding module, and a constant low voltage supply. The pull-up control module includes a first transistor, a second transistor, and a third transistor.