In-Cell Touch Panel Coupling Signal Interference Filtering
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Solution Overview
Problem
In-cell touch display devices suffer from low stability and reliability due to interference from internal parasitic elements and external environmental factors, which affect accurate touch position detection.
Innovation Solution
The implementation of a touch panel with touch sensing units, each comprising a touch sensing element and a coupling sensing element, where the signal processing circuit processes the touch signal based on the coupling signal to filter out interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If touch sensing components are directly built in the LCD panel, then the overall thickness is reduced and manufacturing is simplified, but the sensing signals are susceptible to interference from internal parasitic elements and environmental factors
Solution Approach 1:
The touch sensing unit is segmented into multiple independent pixel units, each containing its own touch sensing element and coupling sensing element. This segmentation allows independent signal processing for each pixel, reducing the impact of parasitic interference on the overall sensing system while maintaining the integrated in-cell structure.
Solution Approach 2:
A coupling sensing element is introduced as an intermediary component between the touch sensing element and the signal processing circuit. The coupling sensing element generates a coupling signal that serves as a reference for compensating parasitic interference, thereby improving signal stability without adding complex external structures.
2Length of stationary object
If touch sensing elements are integrated in the LCD panel, then the device achieves in-cell integration with smaller thickness, but accurate touch position detection is compromised due to interference signals
Solution Approach 1:
The coupling sensing element provides a feedback signal (coupling signal) that reflects the parasitic interference conditions. The signal processing circuit uses this feedback to compensate for and eliminate interference, thereby restoring accurate touch position detection while maintaining the thin in-cell structure.
Solution Approach 2:
The coupling sensing element creates a copy of the interference signal pattern generated by parasitic elements. By processing this copy signal, the system can identify and subtract interference from the touch sensing signal, enabling accurate measurement despite the integrated compact structure.
3Reliability
If multiple sensing elements are added to filter interference, then signal stability improves, but the device complexity increases
Solution Approach 1:
The coupling sensing element serves multiple functions: it generates a coupling signal for interference compensation, acts as a reference for signal processing, and can be integrated into the existing LCD panel structure. This multi-functionality improves signal stability without proportionally increasing device complexity.
Solution Approach 2:
The signal processing circuit changes the parameter processing approach by introducing a coupling signal dimension. Instead of processing only the touch sensing signal, the system processes both the touch signal and coupling signal, using parameter transformation to eliminate interference while maintaining structural simplicity.
Data Source
AI summary
An exemplary embodiment of touch display device includes a touch panel and a signal processing circuit. The touch panel includes a plurality of touch sensing units, and each touch sensing unit includes a touch sensing element and a coupling sensing element. The signal processing circuit is electrically connected to the touch sensing element and the coupling sensing element. The touch sensing element provides a touch signal to the signal processing circuit, the coupling sensing element provides a coupling signal to the signal processing circuit, and the signal processing circuit processes the touch signal according to the coupling signal to filter an interference signal of the touch signal. A touch display device using the touch panel is also described.