Touch Driving Circuit Noise Attenuation via Sample-and-Hold
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Solution Overview
Problem
Existing touch display devices face challenges in enhancing touch sensing sensitivity while minimizing noise interference from parasitic capacitance between touch electrodes and signal lines, which degrades touch sensing performance.
Innovation Solution
A touch driving circuit with sampling blocks, bypass paths, and a differential amplifier, along with a sampling switching block, is implemented to sample and process touch sensing signals, allowing for increased signal magnitude and reduced noise by alternating sampling and bypass operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parasitic capacitance is formed between touch electrode and touch line for touch sensing and electrode and line for display driving, then touch sensing sensitivity is degraded, but noise is increased
Solution Approach 1:
The touch driving circuit is divided into multiple sampling blocks (first sampling block, second sampling block, etc.), each handling signals from different touch lines. This segmentation allows independent processing of signals from different electrodes, enabling selective sampling and noise reduction for each channel while maintaining overall touch sensing sensitivity.
Solution Approach 2:
Different sampling blocks are configured with different sampling timings and paths based on their local requirements. The first sampling block samples signals from the first touch line at different timings than the second sampling block samples signals from the second touch line, allowing optimized noise reduction for each local region while preserving touch sensing sensitivity.
2Reliability
If sampling operation is performed to reduce noise, then signal magnitude increases, but circuit complexity increases
Solution Approach 1:
Multiple sampling blocks are merged into a single integrated touch driving circuit structure, sharing common control logic and timing mechanisms. The sampling blocks process signals from different touch lines but follow unified control signals, reducing overall circuit complexity while maintaining the noise reduction benefits of multiple sampling operations.
Solution Approach 2:
Each sampling block is designed as a multi-functional unit that can handle both touch sensing signals and display driving signals through the same circuit path. The sampling blocks serve multiple purposes: signal amplification, noise reduction, and timing control, thereby reducing the need for separate dedicated circuits and lowering overall complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances touch sensing performance by increasing the integral value of touch sensing signals and reducing noise, thereby improving the overall sensitivity and accuracy of touch detection.
Implementation Method 1
a differential amplifier electrically connected with an output terminal of the sampling switching block
Implementation Method 2
a first sample-and-hold driving path that is configured to sample the first signal
Data Source
AI summary
Embodiments of the disclosure relate to a touch driving circuit and a touch display device. There may be provided a touch driving circuit capable of attenuating noise in the touch sensing signal and enhancing the output signal by the integrator by transferring charge through a sample-and-hold driving path and a bypass driving path, inverting the polarity of the charge sampled by the sampling switching block, and increasing the number of times of sampling. Further, as the amount of charge transferred by the offset voltage control switch included in the sample-and-hold driving path and bypass driving path may be adjusted within an offset voltage range, the performance of touch sensing may be enhanced.