Capacitive Sensor Electrode Layout for Conductor Deposit Detection
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Solution Overview
Problem
Conventional capacitive sensors are prone to erroneously detecting conductor deposits on the detection face due to changes in capacitance between the detection electrode and the conductor, as the drive electrode is often positioned away from the conductor deposit, leading to misinterpretation.
Innovation Solution
The capacitive sensor design includes a detection electrode with first detection lines arranged on a substrate and a drive electrode with first drive lines positioned between adjacent detection lines, allowing for changes in both first and second capacitances to be detected, reducing the likelihood of misinterpretation by the controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive electrode is positioned away from the detection electrode (side-by-side or surrounding arrangement), then the sensor can perform self-capacitive and mutual capacitive sensing, but conductor deposits on the detection face may not cause sufficient change in the capacitance between the detection electrode and drive electrode, leading to erroneous detection
Solution Approach 1:
The patent introduces a third dimension (depth/thickness direction) by arranging the drive electrode and detection electrode on opposite faces of the substrate, creating overlapping regions. This vertical stacking approach increases the capacitance interaction between electrodes compared to side-by-side arrangements, ensuring that conductor deposits cause sufficient capacitance changes for reliable detection.
Solution Approach 2:
The patent employs a multi-layer substrate structure where the drive electrode and detection electrode are nested within different layers of the substrate. This layered nesting allows the electrodes to be positioned in optimal spatial relationships (overlapping or adjacent) while maintaining electrical isolation through insulating layers, thereby maximizing capacitance sensitivity to conductor deposits.
2Area of stationary object
If the detection electrode and drive electrode are arranged to maximize detection coverage, then the sensor area is充分利用, but the capacitance change caused by conductor deposits may be insufficient to distinguish from actual touch events
Solution Approach 1:
By transitioning from a planar side-by-side arrangement to a three-dimensional overlapping arrangement across substrate layers, the patent increases the effective interaction area between electrodes without expanding the detection face area. This vertical stacking creates stronger electric field coupling, resulting in larger capacitance changes when conductor deposits are present.
Solution Approach 2:
The patent creates regions of high capacitance sensitivity by positioning drive and detection electrodes to overlap or be adjacent in specific locations within the substrate layers. This local optimization of electrode arrangement ensures that conductor deposits in the detection face region produce maximum capacitance changes, while maintaining overall detection face coverage.
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 design enhances the sensor's ability to distinguish between a detection target and conductor deposits by increasing the change in mutual capacitance, thereby improving detection accuracy.
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
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention increases the possibility that a conductor deposit causes a change in a capacitance between a detection electrode and a drive electrode. A capacitive sensor S1 includes a substrate 100, a detection electrode 200, a drive electrode 300, and a controller 500. One or a plurality of layers 110 of the substrate 100 include a first face 110a and a second face 110b. The detection electrode 200 incudes a plurality of first detection lines 210 arrayed at spaced intervals on the first face 110a. The drive electrode 300 includes a plurality of first drive lines 310, each of which is located between adjacent two of the first detection lines 210 on one of the first face 110a or the second face 110b. The controller 500 is configured to charge and discharge the detection electrode 200 and supply drive pulses to the drive electrode 300. The controller 500 is further configured to detect a detection target on the basis of a change in a first capacitance between the detection electrode 200 and the detection target and a change in a second capacitance between the detection electrode 200 and the drive electrode 300.