Gate Driving Unit Potential Maintenance for In-Cell Touch Displays
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Solution Overview
Problem
In in-cell touch displays, the low self-holding capability of the potential of the first node in the Gate On Array (GOA) due to leakage current in thin film transistors leads to display abnormalities, especially at high temperatures, as the potential of the gate driving unit cannot be maintained as a valid voltage during the latch time period.
Innovation Solution
A gate driving unit comprising an input terminal, a latch node control circuit, a first node potential maintenance circuit, and a latch node reset circuit, which control the voltage of the latch node and maintain the potential of the first node through charging and resetting mechanisms, ensuring a valid voltage is maintained during the latch time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the GOA operates in a time-division manner with latch time period for touch scanning, then the touch function is enabled, but the potential of the first node cannot be maintained as a valid voltage due to leakage current
Solution Approach 1:
The patent applies preliminary action by pre-charging the first node to a valid voltage level before the latch time period begins. The charging circuit charges the first node during the display period, and the holding circuit maintains this charged state throughout the latch time period, ensuring the node is ready to resume normal operation without display abnormalities.
Solution Approach 2:
The patent introduces a holding circuit as an intermediary component between the first node and the leakage current path. This holding circuit includes a holding transistor and holding capacitor that actively maintain the potential of the first node during the latch time period, mediating the effect of leakage current to prevent potential degradation.
2Productivity
If the latch time period is extended to complete touch scanning for multiple rows, then the touch scanning coverage is improved, but the display period is reduced
Solution Approach 1:
The patent applies self-service by implementing a self-holding mechanism for the first node potential. The holding circuit automatically maintains the valid voltage level throughout the latch time period without requiring external intervention or reducing the display period, allowing extended touch scanning coverage while preserving full display duration.
3Ease of operation
If the leakage current of TFT is present, then the transistor can operate, but the potential of the first node degrades during latch time period
Solution Approach 1:
The patent converts the harmful effect of leakage current into a beneficial situation by using the holding circuit to actively compensate for the leakage. The holding transistor and capacitor work together to replenish the charge lost to leakage current, transforming the problem of leakage into an opportunity to implement active potential maintenance that ensures reliable operation.
Data Source
AI summary
A gate driving unit includes an input terminal, a latch node control circuit, a first node potential maintenance circuit, and a latch node reset circuit, the latch node control circuit is configured to control a voltage of the latch node through a charging voltage inputted by the latch charging terminal under the control of an input signal provided by the input terminal, the first node potential maintenance circuit is configured to control the connection between the first node and the latch enable terminal under the control of a voltage of the latch node, to maintain a potential of the first node; and the latch node reset circuit is configured to control to reset the potential of the latch node under the control of the latch node reset signal inputted by the latch node reset terminal.