Capacitive Sensor Electrode Layout With Fewer Vias
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Solution Overview
Problem
Conventional capacitive sensors require multiple vias (interlayer wirings) to connect electrodes, increasing costs and complexity, while aiming to reduce the number of inner layers and vias without compromising detection accuracy.
Innovation Solution
The capacitive sensor configuration uses a cascade wiring approach with partial electrodes connected through a single via between layers, reducing the number of inner layers and vias while maintaining detection accuracy by optimizing electrode placement and wiring patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple vias and inner layers are used to connect electrodes in conventional capacitive sensors, then electrode connectivity and detection accuracy are maintained, but manufacturing cost and device complexity increase
Solution Approach 1:
The electrode is divided into multiple partial electrodes (first partial electrode, second partial electrodes) that are spatially separated and connected through wiring. This segmentation allows each partial electrode to be optimally positioned for detection while reducing the need for complex interlayer connections, as each segment can be independently routed with simpler wiring patterns.
Solution Approach 2:
The patent transitions from planar electrode arrangements to a three-dimensional configuration utilizing multiple layers. Detection electrodes are placed on different layers (first layer, second layer) and connected through vias, allowing electrodes to be positioned in three-dimensional space without requiring excessive interlayer connections. This spatial distribution reduces wiring complexity while maintaining detection functionality.
2Reliability
If multiple inner layers and vias are used for electrode wiring, then electrode connectivity is ensured, but production cost increases
Solution Approach 1:
The patent combines multiple wiring functions into a reduced number of vias and inner layers. By carefully planning the wiring paths and utilizing the cascade connection structure, the design achieves necessary electrode connectivity with fewer interlayer transitions, thereby reducing manufacturing steps and production costs associated with multi-layer PCB fabrication.
Solution Approach 2:
The wiring structure is designed to serve multiple functions simultaneously: the same via and wiring path connect multiple partial electrodes, and the cascade connection structure provides both signal routing and electrical connection functions. This multi-functionality reduces the overall number of components and manufacturing steps required.
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 effectively reduces the number of vias and inner layers required, lowering production costs and simplifying the sensor design without compromising detection precision.
Implementation Method 1
A capacitive sensor for detecting a change in electrostatic capacitance caused by proximity of an object such as a finger is conventionally known. When an object approaches these electrodes, electrostatic capacitance (self capacitance) between the electrodes for detection and the object and electrostatic capacitance (mutual capacitance) between the electrodes change
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
Three or more detection electrodes E intersect one another in each of a plurality of sections A that divide a region to which an object is approachable. Each of the detection electrodes E includes a plurality of partial electrodes B connected in cascade via wiring W, and partial electrodes B included in the detection electrodes E that intersect one another in each of the sections A are disposed in the section A. Three or more partial electrodes B disposed in the section A includes a single first partial electrode and at least two second partial electrodes. The first partial electrode is connected in cascade to the partial electrode B on one side through a first-layer wiring or a second-layer wiring and is connected in cascade to the partial electrode on the other side through the second-layer wiring. Each of the second partial electrodes is connected in cascade to the partial electrode B in one side through the first-layer wiring and is connected in cascade to the partial electrode on the other side through the second-layer wiring.