Shift Register Leakage-Proof Module for High Reporting Rate Touch Displays
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Solution Overview
Problem
Existing gate-on-array (GOA) circuits in touch panels with high reporting rates experience abnormal displaying due to electrical leakage issues during alternating display and touch periods.
Innovation Solution
A shift register with a leakage-proof module is implemented, connecting the source of the first thin film transistor to the drain of the second thin film transistor as the first pulling-up node and the capacitor to the gate of the third thin film transistor as the second pulling-up node, with a leakage-proof module controlling the path between these nodes to conduct during display periods and disconnect during touch periods, effectively slowing capacitor discharge and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame period is divided into multiple display periods and touch periods to increase reporting rate, then the touch reporting rate is improved, but capacitor leakage increases causing abnormal displaying
Solution Approach 1:
The patent applies dynamics by making the connection state between the capacitor and pulling-up node changeable rather than fixed. A control transistor is introduced to dynamically switch the capacitor connection: during display periods the capacitor remains connected to maintain gate-on signals, while during touch periods the capacitor is disconnected to prevent leakage. This dynamic state change enables the system to achieve both high touch reporting rate and normal displaying by adapting the capacitor connection state to different operational phases.
2Speed
If the capacitor discharges quickly during touch periods, then the touch response speed is improved, but abnormal displaying occurs due to excessive leakage
Solution Approach 1:
The patent applies the extraction principle by removing the capacitor from the circuit during touch periods. By using a control transistor to disconnect the capacitor from the pulling-up node during touch operations, the harmful leakage effect is extracted or removed from the system when it would otherwise cause problems. This allows the touch period to proceed without the interference of capacitor discharge, preventing abnormal displaying while maintaining touch functionality.
3Reliability
If the capacitor remains connected during touch periods, then displaying normality is maintained, but touch reporting rate decreases
Solution Approach 1:
The patent applies dynamics by making the connection state between the capacitor and pulling-up node changeable rather than fixed. A control transistor is introduced to dynamically switch the capacitor connection: during display periods the capacitor remains connected to maintain gate-on signals, while during touch periods the capacitor is disconnected to prevent leakage. This dynamic state change enables the system to achieve both high touch reporting rate and normal displaying by adapting the capacitor connection state to different operational phases.
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a
AI summary
There is disclosed a shift register, a gate integrated driving circuit and a display screen. In the shift register, a connection point between the source of the first thin film transistor (T1) and the drain of the second thin film transistor (T2) is set as the first pulling-up node (PU1), a connection point between the capacitor (C1) and the gate of the third thin film transistor (T3) is set as the second pulling-up node (PU2), and the leakage-proof module is added between the first pulling-up node (PU1) and the second pulling-up node (PU2). The leakage-proof module is configured to, under the control of the display control signal terminal (CT1): conduct the path between the first pulling-up node (PU1) and the second pulling-up node (PU2) during the display period in a frame, so that the shift register can output a normal gate-on signal; and disconnect the path between the first pulling-up node (PU1) and the second pulling-up node (PU2) during the touch period in the frame, which is equivalent to connecting a resistor having a large resistance in a discharging path of the capacitor (C1) in series, so that the discharging of the capacitor (C1) can be slowed greatly, and a leakage speed of the capacitor (C1) is decreased effectively, which avoids a problem of abnormal displaying occurs possibly in an application of a touch screen with a high reporting rate.