Touch Panel Control Apparatus Gate Drive Noise Synchronization
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Solution Overview
Problem
Touch panels with capacitive touch technology experience gate drive noise, leading to erroneous touch recognition and reduced position detection accuracy, especially in larger screens and direct bonding configurations, where conventional noise avoidance techniques are inadequate.
Innovation Solution
A touch panel control apparatus that generates a delayed gate clock signal by adding a predetermined delay amount to the original gate clock signal, synchronizing the touch panel drive signal with the occurrence timing of gate drive noise to avoid interference and maintain position detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the touch panel is provided to overlap the screen of the liquid crystal display apparatus, then the integration and compactness are improved, but gate drive noise appears in the position signal causing erroneous touch recognition
Solution Approach 1:
The timing detection circuit performs preliminary detection of the liquid crystal drive signal output timing before capturing touch panel data. By detecting the gate drive signal timing in advance and comparing it with the touch panel output timing, the system proactively identifies potential noise interference periods and avoids capturing data during those periods, thus preventing gate drive noise from corrupting the position signal.
2Productivity
If the output data is captured from the touch panel at a predetermined timing, then the scanning efficiency is improved, but the position detection accuracy deteriorates due to gate drive noise
Solution Approach 1:
The system employs periodic scanning of the touch panel with timing adjustments based on the liquid crystal drive cycle. By synchronizing the touch panel data capture with the periodic gate drive signal cycles and avoiding the noise period within each cycle, the system maintains high scanning efficiency while ensuring position detection accuracy is not compromised by gate drive noise.
3Ease of manufacture
If the touch panel is directly bonded to the screen, then the manufacturing complexity is reduced, but the gate drive noise influence increases
Solution Approach 1:
The timing detection circuit acts as an intermediary between the liquid crystal driver and the touch panel control system. It monitors the liquid crystal drive signal timing and uses this information to coordinate the touch panel data capture, effectively mediating the interaction between the two subsystems to prevent the gate drive noise from affecting the touch panel position signal despite the direct bonding configuration.
4Reliability
If the gate drive noise is avoided by skipping scans during noise period, then the noise influence is reduced, but the number of scans is reduced and position detection accuracy is lowered
Solution Approach 1:
The system dynamically adjusts the touch panel data capture timing based on the detected liquid crystal drive signal characteristics. By continuously monitoring the drive signal output timing and adapting the touch panel scan timing accordingly, the system optimizes the scanning schedule to capture data during low-noise periods while maximizing the number of valid scans, thus maintaining both noise avoidance and position detection accuracy.
Data Source
AI summary
A touch panel control apparatus includes a delay setting portion which sets a delay amount corresponding to a first gate clock signal for controlling a driving timing of a gate line provided in a liquid crystal panel, a signal generator which adds the delay amount set by the delay setting portion to the first gate clock signal to generate a second gate clock signal, and a touch panel control board which drives a touch panel based on the second gate clock signal generated by the signal generator. The delay setting portion sets a period from a rising timing of the first gate clock signal to immediately before a timing at which noise appearing on the position signal by driving the gate line occurs to the delay amount.