Capacitive Touch Electrode Layout for Palm and Fingertip Detection
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Solution Overview
Problem
Existing touch switches struggle to accurately determine the type of operation input based on capacitance values, as these values differ significantly between fingertip and palm touches due to variations in the size and distance of the operation body from the electrode, leading to potential erroneous determinations.
Innovation Solution
The input device employs a plurality of electrodes adjacent to operation areas, using algorithms to detect and correct capacitance values by subtracting a weighted sum of adjacent electrode values, allowing accurate determination of operation inputs regardless of the size of the operation body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitance values are used to detect operation inputs, then operation detection is enabled, but detection accuracy deteriorates due to variations in operation body size and distance
Solution Approach 1:
The electrode array is divided into multiple individual electrodes, allowing the system to analyze capacitance patterns across different positions. By segmenting the detection area into discrete electrodes, the system can distinguish between operation bodies of different sizes and distances based on their unique capacitance distribution patterns, thereby improving detection accuracy and determination reliability
Solution Approach 2:
The system changes the parameter analysis approach by not only detecting capacitance values but also calculating differences between adjacent electrode capacitance values. This parameter transformation allows the system to differentiate between operation bodies based on their spatial capacitance distribution, resolving the issue of inaccurate detection caused by variations in operation body size and distance
2Measurement precision
If a single electrode is used for detection, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish operation body characteristics
Solution Approach 1:
The detection area is segmented into multiple electrodes arranged in an array, enabling the system to capture spatial variations in capacitance. This segmentation provides rich information about operation body characteristics without requiring complex additional sensors, achieving high measurement precision with a relatively simple electrode-based structure
Solution Approach 2:
The electrode array serves multiple functions: detecting operation body presence, determining operation body size, and estimating distance. By making the electrode system multi-functional, the patent achieves comprehensive operation detection capabilities without adding separate specialized sensors, thus balancing measurement precision with device 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
The device effectively distinguishes between different operation inputs, such as those made by fingertips, finger cushions, or palms, ensuring precise operation detection and reducing false determinations.
Implementation Method 1
a plurality of detection means for detecting a change in physical quantity caused by the approach of an object (operation body) to the operation surface... the capacitance values detected at an electrode are different when a fingertip touches the operation surface and when a palm touches the operation surface
Data Source
AI summary
An input device includes electrodes, a detection section configured to detect capacitance values of the electrodes, and a determination section configured to determine whether an operation input has been performed by an operation body to an operation area of operation areas based on the capacitance values. The electrodes correspond to the operation areas and are disposed adjacent to each other on the back sides of the operation areas. The determination section determines whether the operation input has been performed on the operation area corresponding to one electrode of the electrodes based on a difference value obtained by subtracting a value obtained by multiplying capacitance values of electrodes adjacent to one electrode by a coefficient k, k being 0<k<1, from the capacitance value of one electrode.