Capacitive Touch Peak Sensing for Faster Differential Detection
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Solution Overview
Problem
Existing touch input detection technologies are burdensome in terms of computing resources, particularly when rapid measurements are required for time domain differential processing.
Innovation Solution
Systems and methods that measure peak voltage at an electrode over a measurement period and defer digital signal processing until after peak electrode capacitance has been sampled, suitable for capacitive sensors using self-capacitance and mutual capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital signal processing is performed on each electrode output as it is sampled, then time domain differential processing can be performed, but computing resources are burdened and measurement speed is reduced
Solution Approach 1:
The patent applies preliminary action by performing peak detection on electrode outputs before digital signal processing. The measurement circuit identifies peak voltages of electrode signals and holds these peak values, so that subsequent time domain differential processing only needs to operate on already-processed peak data rather than raw continuous signals, thereby reducing computing resource burden while maintaining detection accuracy
Solution Approach 2:
The patent extracts only the essential information (peak voltage values) from the electrode signals before digital processing. By using peak detectors to extract maximum voltage points and holding circuits to maintain these extracted values, the system eliminates the need to process entire signal waveforms, significantly reducing computational complexity while preserving the touch detection capability
2Measurement precision
If digital signal processing is performed on each electrode output as it is sampled, then time domain differential processing can be performed, but measurement speed is reduced
Solution Approach 1:
The measurement circuit performs preliminary peak detection and signal conditioning before the outputs reach the digital signal processing stage. By pre-identifying peak voltages and holding these values, the system prepares data in advance for differential processing, enabling faster measurement cycles without sacrificing the accuracy needed for reliable touch detection
Solution Approach 2:
The patent segments the signal processing task into two distinct stages: (1) analog peak detection and holding in the measurement circuit, and (2) digital time domain differential processing. This segmentation allows the analog circuit to handle rapid signal sampling and peak identification at high speed, while the digital processor only needs to perform simpler differential calculations on the already-prepared peak data, thereby increasing overall measurement speed
3Productivity
If peak voltage measurement and deferred digital signal processing are used, then computing resources are conserved and measurement speed increases, but the system must accurately capture peak values
Solution Approach 1:
The patent introduces peak detectors and holding circuits as intermediary components between the electrode signals and the digital signal processing stage. These intermediaries accurately capture peak voltage values through dedicated analog circuitry designed for precision peak detection, then maintain these captured values until processing is complete, ensuring that no accuracy is lost in the transition to faster measurement methods
Solution Approach 2:
The patent replaces complex digital signal processing operations with simpler analog peak detection circuitry for the initial measurement stage. By using analog holding circuits to capture and maintain peak voltages rather than relying on continuous digital processing, the system achieves both high measurement speed and accurate peak capture, with the analog circuitry handling the precision measurement function more efficiently
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
Conserves computing resources and enables rapid touch input detection by minimizing digital signal processing, suitable for capacitive buttons, track pads, and touch screens.
Implementation Method 1
the capacitive sensor includes a driver circuit, a measurement circuit, and a signal processing circuit. The driver circuit is adapted to providing a stimulus voltage, for example a repeating square wave, to a capacitive coupling.
Implementation Method 2
The measurement circuit includes a peak detector and provides an output proportional to the peak voltage across the capacitive coupling over a measurement period
Data Source
AI summary
Systems and methods for determining a touch input are provided. The systems and methods generally include measuring the peak voltage at an electrode over a measurement period and determining a touch input based on the peak voltage. The systems and methods can conserve computing resources by deferring digital signal processing until after a peak electrode capacitance has been sampled. The systems and methods are suitable for capacitive sensors using self-capacitance and capacitive sensors using mutual capacitance. The systems and methods are also suitable for capacitive buttons, track pads, and touch screens, among other implementations.