Capacitive Touch Sensor Loops for Precise Large-Surface Detection
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Solution Overview
Problem
Conventional capacitive sensor systems face inaccuracies in touch detection on large surfaces due to slow signal drop-off beyond the sensor edge, leading to ambiguous threshold conditions and incorrect function association, especially when dealing with varying finger sizes and glove usage.
Innovation Solution
A capacitive sensor system with two parallel, non-touching closed conductor loops on the sensor surface, where the evaluation device determines a ratio value from the difference and sum of sensor signals to accurately detect touches, reducing dependency on finger size and improving detection precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a full-surface sensor electrode is used for each individual operating surface, then the touch detection coverage is improved, but the signal drop-off beyond the sensor edge becomes slow, causing inaccurate touch detection outside the operating surface
Solution Approach 1:
The sensor surface is divided into multiple independent sensor electrodes, each with its own closed conductor loop. This segmentation allows each electrode to have a well-defined sensing area with rapid signal drop-off at the edges, preventing signal leakage between adjacent operating surfaces while maintaining full coverage.
Solution Approach 2:
Each sensor electrode is designed with a closed conductor loop that creates a localized sensing field with rapid signal decay at the boundaries. This local quality ensures that touch detection is accurate and confined to the intended operating surface, even when multiple surfaces are adjacent to each other.
2Adaptability or versatility
If the sensor surface is made much larger than the finger, then the system can accommodate different finger sizes and glove usage, but the sensor signal drops off slowly beyond the edge, resulting in inaccurate touch detection
Solution Approach 1:
The large sensor surface is segmented into multiple smaller sensor electrodes, each with its own closed conductor loop. This allows the system to maintain large overall coverage for versatility while each individual electrode provides precise signal localization with rapid edge drop-off, solving the contradiction between size and precision.
Solution Approach 2:
Multiple sensor electrodes with closed conductor loops are arranged in a nested or adjacent configuration, where each loop is contained within or next to the overall sensor surface boundary. This nesting allows the system to achieve both large coverage area and precise local signal detection.
3Ease of manufacture
If the interior region of the sensor surface is excluded for lighting elements, then lighting integration is improved, but the sensor signal drops off further, requiring lower threshold values and causing touch detection to migrate outside the operating surface
Solution Approach 1:
The sensor surface is segmented into multiple sensor electrodes with closed conductor loops that can be arranged to exclude interior regions for lighting elements. Each electrode maintains its own closed loop structure, ensuring that touch detection remains accurate at the operating surface boundaries even when interior areas are removed for lighting.
Solution Approach 2:
Each sensor electrode maintains localized sensing quality with rapid signal drop-off at its boundaries, independent of interior exclusions. This allows lighting elements to be integrated in interior regions while each electrode continues to provide accurate touch detection at its designated operating surface area.
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 system provides precise touch detection on large surfaces, minimizing errors and allowing for accurate delimitation of touch areas, regardless of finger size, and enables flexible adaptation to operator panel geometry, with potential use of inner spaces for additional features like lighting elements.
Implementation Method 1
capacitive sensor system for touch detection, the capacitive sensor system including a sensor surface on which at least one sensor electrode is situated and an evaluation device for evaluating an electrical sensor signal of the sensor electrode that is influenceable by the position of a measured object
Data Source
AI summary
A capacitive sensor system for touch detection includes a sensor surface, a first sensor electrode, a second sensor electrode, and an evaluation device. The sensor electrodes are both situated on and border the sensor surface. The first sensor electrode has a first closed conductor loop and the second sensor electrode has a second closed conductor loop. The first closed conductor loop surrounds the second closed conductor loop without the closed conductor loops touching each other. Each sensor electrode generates a sensor signal that depends on a position of a touch of an object on the sensor surface relative to the closed conductor loop of the sensor electrode. The evaluation device detects the touch based on a comparison of a ratio value to a threshold value, wherein the ratio value is a ratio of (i) a difference and (ii) a sum of the sensor signals.