Dual-Mode Capacitive Sensing for Independent Proximity and Displacement
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Solution Overview
Problem
Capacitive sensing technologies face challenges in simultaneously detecting displacement and proximity, as the presence of objects can affect capacitance measurements, making it difficult to distinguish between displacement and proximity events, and existing solutions do not effectively address the need for independent detection of both in various scenarios.
Innovation Solution
A capacitive sensor system that operates in both displacement sensing and proximity sensing modes by switching the connection of electrodes to capacitance measurement circuitry, allowing for independent measurement of displacement and proximity through changes in capacitive coupling between deformable and reference electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensing techniques are used to detect displacement, then reliability is improved compared to mechanical switching, but the presence of approaching objects affects capacitance measurements and causes false displacement detection
Solution Approach 1:
The sensor is divided into two functionally independent parts: a first electrode for proximity detection and a second electrode for displacement detection. This segmentation allows each electrode to be optimized for its specific function, with the first electrode detecting approaching objects and the second electrode measuring actual displacement, thereby eliminating false detections while maintaining reliability
Solution Approach 2:
The first electrode acts as an intermediary that detects approaching objects before they cause displacement. By providing early warning of object proximity, it allows the system to distinguish between objects that will cause displacement versus those that merely approach, preventing false displacement measurements
2Measurement precision
If the sensor is designed to reduce sensitivity to approaching objects, then false displacement detection is reduced, but the ability to detect proximity is lost
Solution Approach 1:
The sensor achieves multi-functionality by using two electrodes that can independently perform different functions. The first electrode is optimized for proximity detection while the second electrode is optimized for displacement detection, allowing the sensor to provide both proximity and displacement information simultaneously without compromise
3Device complexity
If a single electrode is used for both proximity and displacement detection, then device complexity is reduced, but the ability to independently detect both parameters is compromised
Solution Approach 1:
The sensor is divided into two functionally independent parts: a first electrode for proximity detection and a second electrode for displacement detection. This segmentation allows each electrode to be optimized for its specific function, with the first electrode detecting approaching objects and the second electrode measuring actual displacement, thereby eliminating false detections while maintaining reliability
Solution Approach 2:
The sensor achieves multi-functionality by using two electrodes that can independently perform different functions. The first electrode is optimized for proximity detection while the second electrode is optimized for displacement detection, allowing the sensor to provide both proximity and displacement information simultaneously without compromise
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
Enables accurate detection of displacement and proximity events, reducing false determinations and improving sensitivity by isolating the effects of approaching objects on capacitance measurements, thereby enhancing the reliability of capacitive sensing in touch-sensitive applications.
Implementation Method 1
a first electrode; a displacement element moveably mounted relative to the first electrode... in the proximity sensing mode, the controller element is configured to measure a capacitance characteristic of the first electrode to detect the proximity of a conductive object
Implementation Method 2
a second electrode coupled to the displacement element so that displacement of the displacement element changes a separation between the first electrode and the second electrode... in the displacement sensing mode, the controller element is configured to measure a capacitance characteristic of the second electrode to determine the displacement of the displacement element
Data Source
Figure 1~3
Figure 4A~5
Figure 6~7B
AI summary
A capacitive sensor comprising: a first electrode; a displacement element moveably mounted relative to the first electrode; and a second electrode coupled to the displacement element so that displacement of the displacement element along a displacement direction changes a separation between the first electrode and the second electrode; and a controller element configured to selectively operate in a displacement sensing mode and in a proximity sensing mode, wherein in the displacement sensing mode, the controller element is configured to electrically couple the second electrode to a reference potential and to electrically couple the first electrode to capacitance measurement circuity to measure a capacitance characteristic of the first electrode to determine a displacement of the displacement element relative to the reference electrode; and in the proximity sensing mode, the controller element is configured to electrically couple the second electrode to capacitance measurement circuity to measure a capacitance characteristic associated with the second electrode to detect the presence of an object in proximity to the second electrode; and in the displacement sensing mode, the controller element is configured to electrically couple the second electrode to a reference potential signal.