GOA Circuit Pull-Down Maintaining Unit for Liquid Crystal Panel
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Solution Overview
Problem
The existing GOA circuit in liquid crystal panels experiences reliability issues due to a mutually restrained charging condition during the pre-charging process, leading to potential instability and malfunction over time.
Innovation Solution
The redesign of the pull-down maintaining unit in the GOA circuit includes a second transistor that turns off the first transistor in response to an upper-level pre-charging signal before the present-level pre-charging node is pre-charged, ensuring complete disconnection from the low supply voltage wire, thereby preventing unexpected potential changes in the pre-charging node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pull-down maintaining unit uses a Darlington inverter configuration with transistors T42 and T54, then the circuit can maintain low potential at the pre-charging node, but the pre-charging node potential is unexpectedly pulled down during pre-charging process due to mutual restraint between charging conditions
Solution Approach 1:
The patent applies preliminary action by turning off transistor T42 before the pre-charging process begins. The control signal turning_off_T42 is activated in advance to ensure T42 is completely off before the pre-charging node starts charging, preventing the mutual restraint problem that occurs when T42 is turned off during the charging process. This preliminary action eliminates the unexpected potential pull-down issue.
Solution Approach 2:
The patent applies preliminary anti-action by proactively turning off transistor T42 before the pre-charging operation starts. By anticipating the potential conflict between T42's pull-down function and the pre-charging operation, the control signal turning_off_T42 is activated in advance to prevent the harmful mutual restraint effect from occurring in the first place.
2Stability of the object's composition
If transistor T42 is turned off during the pre-charging process to prevent potential pull-down, then the pre-charging node can be charged properly, but the timing coordination becomes complex and may cause malfunction over time
Solution Approach 1:
The patent resolves the timing coordination complexity by turning off transistor T42 in advance before the pre-charging process begins, rather than attempting to coordinate its turn-off timing during the charging process. This eliminates the complex timing requirements and potential coordination errors that could lead to malfunction over time.
Solution Approach 2:
The patent segments the control signals into distinct functional groups: signals for turning off transistors (turning_off_T42, turning_off_T54) are separated from pre-charging signals (pre_charging_signal). This segmentation clarifies the control logic and reduces timing coordination complexity by making the turn-off actions independent preliminary steps.
3Use of energy by moving object
If the pre-charging node is charged to high potential through transistor T11, then the pre-charging function is achieved, but transistor T54 cannot be completely turned on due to insufficient potential, causing T42 to remain partially on and pull down the node potential
Solution Approach 1:
The patent applies preliminary action by turning off transistor T42 before the pre-charging process begins. This eliminates the need for T54 to be completely turned on during pre-charging, as T42 is already off and cannot pull down the node potential. The insufficient potential issue during pre-charging becomes irrelevant since T42 is preemptively disabled.
Solution Approach 2:
The patent extracts transistor T42 from the active circuit during the pre-charging process by turning it off. This removes the conflicting pull-down function from the circuit when pre-charging is occurring, allowing T11 to charge the pre-charging node to high potential without the opposing force from T42, regardless of T54's switching state.
Data Source
AI summary
There provides a liquid crystal panel including a GOA circuit and a driving method thereof, the GOA circuit including a plurality of single-level GOA circuit units that are cascaded, wherein each single-level GOA circuit unit includes a pull-down maintaining unit, the pull-down maintaining unit including a first transistor having a gate connected to a first node, a source connected to a present-level pre-charging node, and a drain connected to a low supply voltage wire; and a second transistor having a gate connected to an upper-level pre-charging node so as to receive a pre-charging signal from the upper-level pre-charging node and a drain connected to the low supply voltage wire, wherein the second transistor is configured to turn off the first transistor in response to an upper level pre-charging signal before the present-level pre-charging node is pre-charged.