Gate Drive Circuit for Fast LCD Power-Off Image Clearing
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Solution Overview
Problem
Existing gate driving circuits for liquid crystal displays struggle to quickly clear residual images when power is turned off, leading to image retention issues due to the output of high potentials during power shutdown.
Innovation Solution
A gate driving circuit design incorporating pull-up and pull-down control modules that generate specific control signals to manage potential outputs, ensuring the output terminal of the Nth-stage gate driving unit outputs a high potential when power is turned off, effectively preventing image retention by utilizing a cascaded stage configuration of thin film transistors and capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the GOA drive circuit outputs a high potential when power is turned off according to a first global control signal, then the liquid crystal screen can maintain the image displayed previously, but the GOA circuit cannot clear the image on the display quickly
Solution Approach 1:
The patent implements dynamic control of the GOA circuit output by switching between two modes: normally, the circuit outputs high potential to maintain images, but when power is turned off, it transitions to outputting low potential through the pull-down module to quickly clear residual images. This dynamic switching resolves the contradiction between image retention and quick clearing capability.
Solution Approach 2:
The patent changes the output potential parameter of the GOA circuit based on power state. During normal operation, the output potential is maintained at high level for image retention. When power is turned off, the output potential parameter is changed to low level through the pull-down control module and pull-down output module, enabling fast clearing of residual images while preventing the screen from displaying previous content.
2Device complexity
If conventional GOA circuits are used without pull-down modules, then the circuit structure is simpler, but residual images remain on the display when power is turned off
Solution Approach 1:
The patent merges the pull-down control module and pull-down output module with the existing GOA circuit structure. The pull-down control module integrates with the clock signal generation, and the pull-down output module connects to the GOA output terminal, forming a unified circuit that maintains simplicity while adding residual image clearing capability through coordinated operation of existing and new components.
Data Source
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Figure 3
AI summary
A gate drive circuit, comprising: a pull-up control module (101, 201), used for generating a first control signal in the case of power outage; a pull-up output module (102, 202), used for outputting high level under the control of the first control signal; a pull-down control module (103, 203), used for generating a second control signal in the case of power outage; and a pull-down output module (104, 204), used for outputting low level under the control of the second control signal. The output end of the pull-up output module (102, 202) and the output end of the pull-down output module (104, 204) are connected to the output end of an Nth gate drive unit. During power outage, the pull-up output module (102, 202) and the pull-down output module (104, 204) enable the output end of the Nth gate drive unit to output high level. In the case that sudden power outage occurs during use of a liquid crystal screen, the image on the screen can be quickly cleared, and the appearance of image sticking in the display is avoided.