Capacitive Touch Signal Evaluation for Unintended Input Suppression
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Solution Overview
Problem
Touch-sensitive capacitive operating elements, especially small ones like volume sliders, face issues with unintended control inputs due to slight tilting or rolling movements of the finger, leading to incorrect operation and user frustration.
Innovation Solution
A method that discards or suppresses the output of finger position calculations during large-area coverage or excessive sensor stroke variations, using preset values to differentiate between intended and unintended movements, and adapts to individual user behavior by learning their high-frequency oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If finger position is calculated from sensor strokes during placement and tilting, then control input is generated, but unintended control operations occur
Solution Approach 1:
The system performs preliminary detection of finger placement and tilting movements before generating control inputs. By evaluating sensor stroke differences and comparing them against threshold values during the placement phase, the system identifies unintended movements and prevents them from triggering control operations, thereby ensuring only intentional inputs are executed
Solution Approach 2:
The system continuously monitors sensor stroke differences and provides feedback to determine whether a detected movement represents an intentional input or an unintended placement/tilting artifact. This feedback mechanism allows the system to dynamically adjust its response based on the characteristics of the detected movement, improving control input accuracy
2Measurement precision
If sensor strokes are used to calculate finger position, then finger position is determined, but slight tilting or rolling movements cause position displacement
Solution Approach 1:
The system applies different evaluation criteria to different phases of finger interaction with the touch-sensitive element. During the placement phase, the system uses threshold-based filtering to tolerate minor tilting and rolling movements, while during the active input phase, it maintains high precision for position determination. This localized quality adjustment resolves the contradiction between measurement precision and ease of operation
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 significantly reduces incorrect inputs, ensuring only intended control actions are implemented, enhancing user experience and accuracy in controlling touch-sensitive elements like steering wheel volume sliders.
Implementation Method 1
touch-sensitive capacitive operating element
Data Source
AI summary
Signal of inputs made by a finger on a touch-sensitive capacitive operating element are evaluated by calculating a finger position from sensor strokes of individual capacitive sensors. The calculated finger position is not output if a difference between the maximum and minimum sensor stroke of the sensors is smaller than a preset value or smaller than the error tolerance of the sensors. The finger position is output if the difference between the maximum and minimum sensor stroke of the sensors is greater than the first preset value and if the sensor stroke of a sensor closest to the detected finger position at the edge of the touch-sensitive capacitive operating element is smaller than a second preset value.