Capacitive Sensor Electrode Layout for False Touch Discrimination
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Solution Overview
Problem
Conventional capacitive sensors may erroneously detect a conductor deposit as a detection target due to changes in capacitance, as the conductor deposit can alter the capacitance between the detection electrode and the drive electrode without affecting the capacitance between the drive electrode and the detection electrode.
Innovation Solution
The capacitive sensor design includes a substrate with a detection electrode and a drive electrode, where the drive electrode is positioned between adjacent detection lines, allowing a conductor deposit to change the mutual capacitance between the drive and detection electrodes, reducing the likelihood of false detection by ensuring that changes in capacitance are more pronounced and distinct.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drive electrode is arranged surrounding the detection electrode or on the opposite face, then the sensor can detect touch through combined capacitive sensing, but conductor deposits may be erroneously detected as detection targets due to insufficient change in mutual capacitance
Solution Approach 1:
The drive electrode is divided into multiple segments positioned between adjacent detection electrodes, rather than forming a single surrounding electrode. This segmentation allows each drive electrode segment to create distinct mutual capacitance zones with neighboring detection electrodes, enhancing the ability to detect conductor deposits through localized capacitance changes.
Solution Approach 2:
The drive electrode acts as an intermediary element positioned between detection electrodes to mediate the detection of conductor deposits. By supplying drive signals through these intermediate drive electrodes, the system can detect changes in mutual capacitance caused by conductor deposits without requiring the detection electrode itself to be directly involved in the mutual capacitance measurement.
2Device complexity
If the drive electrode is positioned to overlap the detection electrode, then the mutual capacitance measurement is simplified, but conductor deposits located above the detection electrode may not sufficiently affect the second capacitance
Solution Approach 1:
The drive electrodes are positioned in a different spatial arrangement than simple overlap - they are placed between adjacent detection electrodes on the same face or on the opposite face, creating a different geometric relationship. This dimensional repositioning ensures that conductor deposits above detection electrodes will affect the mutual capacitance between the detection electrode and the adjacent drive electrode segments.
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 configuration enhances the sensor's ability to differentiate between a detection target and a conductor deposit, reducing false positives by increasing the likelihood that the conductor deposit will alter the second capacitance, thereby accurately distinguishing between the two.
Implementation Method 1
the controller deactivates the detection electrode and activates the drive electrode, resulting in electrostatic coupling between the drive electrode and the detection electrode
Implementation Method 2
there is a change in a first capacitance between the detection electrode and the detection target... there is a change in a second capacitance between the drive electrode and the detection electrode
Data Source
AI summary
A capacitive sensor including a substrate, detection and drive electrodes, and a controller. The substrate includes one or a plurality of insulating layers including first and second faces. The detection electrode includes mutually electrically connected detection lines arrayed at spaced intervals on the first face. The drive electrode includes mutually electrically connected drive lines each arranged on the first or second face and located between adjacent two of the detection lines. When a target approaches the detection electrode being charged and discharged by the controller, the approach causes a change in a first capacitance between the detection electrode and the target. When a target approaches the detection and drive electrodes while the controller is supplying drive pulses to the drive electrode, the approach causes a change in a second capacitance between the detection electrode and the drive electrode. The controller detects the target referring to changes in the first and second capacitances.