Touch Panel Drive Signal Amplification for Low-Noise Detection
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Solution Overview
Problem
Existing touch panel devices face challenges in accurately detecting touch operations due to low signal-to-noise ratios, especially when the change in capacitance is small, leading to reduced detection accuracy and increased noise interference.
Innovation Solution
The implementation of a drive signal amplifier circuit and a pulse waveform deformation circuit to amplify the drive signal and adjust the pulse rise time, respectively, which improves the signal-to-noise ratio and reduces noise interference, thereby enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a drive signal is input to electrode lines in a conventional touch panel, then the touch panel can detect capacitance changes at intersection points, but the signal-to-noise ratio is low especially when capacitance change is small, leading to reduced detection accuracy
Solution Approach 1:
The patent applies preliminary action by deforming the pulse waveform of the drive signal before it reaches the electrode lines. Specifically, the rise time of the pulse signal is extended by adding a waveform deformation circuit that includes a capacitor and resistor. This preliminary deformation of the drive signal waveform before application to the electrodes reduces noise interference and improves the signal-to-noise ratio, thereby enhancing detection accuracy for small capacitance changes
2Speed
If the pulse rise time is short, then the response speed is fast, but leakage current increases and detection consistency across different areas deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the pulse signal parameters, specifically the rise time. A waveform deformation circuit comprising a capacitor (0.01µF) and resistor (100Ω) is introduced to extend the rise time of the pulse signal from the drive circuit to the electrode lines. This parameter adjustment reduces leakage current and improves detection consistency across different areas of the touch panel while maintaining acceptable response speed
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
The solution effectively increases the signal-to-noise ratio and reduces leakage current, resulting in improved detection accuracy and consistency across different areas of the touch panel, even when the change in capacitance is small.
Implementation Method 1
a drive signal amplifier circuit to amplify the drive signal
Implementation Method 2
a pulse waveform deformation circuit to amplify the drive signal and adjust the pulse rise time
Data Source
AI summary
A touch panel device includes a plurality of first and second electrode lines, a drive signal generation circuit, a sensing signal receiving circuit, and a drive signal amplifier circuit. The first electrode lines extend in a first direction. The second electrode lines extend in a second direction intersecting the first direction. The drive signal generation circuit generates a drive signal input to the first electrode lines. The sensing signal receiving circuit receives a sensing signal output from the second electrode lines and according to magnitude of capacitance at each of intersection points where the first and second electrode lines intersect each other. The drive signal amplifier circuit amplifies each drive signal input to the first electrode lines. An amplified drive signal amplified with the drive signal amplifier circuit is input to the first electrode lines.