Capacitive Touch Panel Drive Signal Modulation for Noise Reduction
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Solution Overview
Problem
Capacitive touch panels face noise interference issues due to external factors, which affect their accuracy and reliability in detecting touch inputs.
Innovation Solution
The implementation of a drive signal with varying characteristics such as frequency, phase, and amplitude across different time intervals, using a digitally controlled oscillator and a lookup table to cycle through pre-selected or random signal characteristics, helps minimize noise interference by modulating the drive signal and employing frequency hopping techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive touch panel uses a constant drive signal, then the system is simple to implement, but it is susceptible to noise interference from external factors
Solution Approach 1:
The patent applies dynamics by transitioning from a constant drive signal to a time-varying drive signal that changes frequency, phase, and/or amplitude across different time intervals. This dynamic signal modulation makes the system resistant to stationary noise interference while maintaining implementation feasibility through systematic parameter variation.
Solution Approach 2:
The patent implements parameter changes by systematically varying one or more signal characteristics (frequency, phase, amplitude) of the drive signal across multiple time intervals. This parameter variation technique effectively distinguishes the signal from external noise sources and improves noise immunity without requiring overly complex modulation schemes.
2Reliability
If the drive signal characteristics are changed frequently to reduce noise, then noise interference is reduced, but the complexity of signal control increases
Solution Approach 1:
The patent applies segmentation by dividing the signal transmission into discrete time intervals, where each interval uses specific signal characteristics. This segmentation approach allows systematic control of signal variations, making the complex noise-reduction strategy manageable through structured time-based parameter changes.
Solution Approach 2:
The patent implements periodic action by cycling through predefined signal characteristics in a repeated pattern across time intervals. This periodic variation of frequency, phase, and/or amplitude creates a predictable signal structure that can be effectively differentiated from random noise, improving detection accuracy while maintaining control simplicity.
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 approach enhances the accuracy and reliability of touch panel systems by reducing external noise interference, allowing for simultaneous detection of multiple touches and improved interaction with electronic devices.
Implementation Method 1
As the human body is also an electrical conductor, touching the surface of the panel results in a distortion of the panel's electrostatic field, measurable as a change in capacitance.
Implementation Method 2
touching the surface of the panel results in a distortion of the panel's electrostatic field
Data Source
AI summary
A capacitive touch panel may include a driver and a drive electrode configured to be connected to the driver. The driver is configured to power the drive electrode with a drive signal having a first signal characteristic during a first time interval, and a second signal characteristic different from the first signal characteristic during a second time interval subsequent to the first time interval. The first signal characteristic may comprise one or more of a first frequency, a first phase, or a first amplitude during the first time interval, and the second signal characteristic may comprise one or more of a second frequency, a second phase, or a second amplitude, where one or more of the first frequency, first phase, or first amplitude may be different from one or more of the second frequency, second phase, or second amplitude, respectively.