GOA Circuit Second Pull-Down for Power Loss Flicker
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display panels experience sticking and flicker issues when power is unexpectedly lost due to the inability of GOA circuits to effectively implement the ALL Gate On function, leading to signal superposition and inadequate release of gate driving signals.
Innovation Solution
A GOA circuit design incorporating a second pull-down circuit connected to the gate of the 5th thin-film-transistor, which pulls down the voltage level when the panel is out of power, preventing signal superposition and ensuring proper gate driving signal release by controlling the 5th and 7th thin-film-transistors as non-conducting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the GOA circuit uses conventional TFT array fabricate process to implement gate scan driving signal circuit, then manufacturing cost is reduced and yield is improved, but the circuit cannot effectively realize ALL Gate On function when out of power abnormally causing sticking and flicker
Solution Approach 1:
The patent applies preliminary anti-action by introducing a second pull-down circuit that proactively pulls down the gate voltage of the 5th thin-film-transistor when power is lost. This preemptive measure prevents the harmful state (sticking and flicker) from occurring in the first place by ensuring that the pixel units can still release their charges even when the normal power supply fails, thus counteracting the potential harm before it manifests.
Solution Approach 2:
The patent uses an intermediary mechanism by adding a second pull-down circuit that acts as a mediator between the power supply failure and the pixel units. This intermediary circuit ensures that when the primary power supply fails, the gate voltage of the 5th thin-film-transistor can still be controlled to allow charge release, thus mediating the impact of power failure on the display performance.
2Ease of operation
If the (n+1)-th clock signal is in high voltage level when out of power abnormally, then the forward scan control signal and (n+1)-th clock signal are pulled down to low voltage level, but the high voltage level of the gate of the thin-film-transistor NT5 cannot be released causing NT5 kept conducting
Solution Approach 1:
The second pull-down circuit applies preliminary anti-action by pre-establishing a path to pull down the gate voltage of the 5th thin-film-transistor when power is lost. This prevents the harmful state where the transistor remains conducting by proactively counteracting the voltage level issue before it causes sticking and flicker.
Solution Approach 2:
The patent changes the voltage parameter of the gate of the 5th thin-film-transistor by introducing a second pull-down circuit. This circuit ensures that the gate voltage can be effectively pulled down to low level even when the normal power supply fails, thus changing the electrical parameter to restore proper transistor switching behavior.
3Device complexity
If the high voltage signal VGH and the low voltage signal VGL are in superposition, then the gate of the thin-film-transistor NT7 cannot be pulled down completely causing gate driving signal G(n) to be pulled low
Solution Approach 1:
The patent extracts the harmful superposition effect by introducing a second pull-down circuit that independently controls the gate voltage of the 5th thin-film-transistor. This extraction separates the voltage control from the superimposed signals, ensuring that the gate driving signal can be properly maintained without being affected by the superposition of VGH and VGL.
Solution Approach 2:
The second pull-down circuit acts as an intermediary that mediates between the superimposed voltage signals and the gate of the 5th thin-film-transistor. It ensures that despite the superposition of VGH and VGL, the gate voltage can still be effectively controlled to prevent the transistor from remaining conducting, thus protecting the gate driving signal integrity.
Data Source
AI summary
GOA circuit is disclosed comprising m stages GOA units, wherein a n-th stage GOA unit comprises: an output control module, a forward-backward scan control module, a node signal control module, a signal output module, a first pull-down circuit, a second pull-down circuit, and a pull-up circuit, wherein m≥n≥1; output control module controls a n-th stage gate driving signal; first pull-down circuit comprises a 7th thin-film-transistor which first end connected with said output control module, and second end connected with low voltage signal; signal output module comprises a 5th thin-film-transistor which first end connected with high voltage signal and second end connected with third end of said 7th thin-film-transistor; node signal control module controls said 5th thin-film-transistor as conducting or non-conducting; second pull-down circuit controls said 5th thin-film-transistor as non-conducting. Present invention eliminates the sticking and flicker of display panels after out of power improving user experience.