Capacitive Sensor Shield Layer Reduces Parasitic Capacitance
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Solution Overview
Problem
Conventional electrostatic capacitance detection devices face a trade-off between maintaining detection sensitivity and preventing electromagnetic interference (EMI), where increasing parasitic capacitance between the electrode and shield layers reduces sensitivity and operability.
Innovation Solution
The electrostatic capacitance detection device features a shield layer formed on the rear surface of the substrate without overlapping with the electrode layer, surrounding the electrodes and wirings, and electrically connected between them, minimizing parasitic capacitance while effectively preventing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield layer is formed on the substrate to prevent EMI, then electromagnetic interference prevention is improved, but parasitic capacitance between the electrode layer and shield layer increases, reducing detection sensitivity
Solution Approach 1:
The patent positions the shield layer on the rear surface of the substrate while the electrode layer is on the front surface, utilizing the thickness dimension of the substrate to spatially separate the two layers. This dimensional arrangement reduces parasitic capacitance between the layers while maintaining EMI shielding effectiveness, thereby resolving the contradiction between EMI prevention and detection sensitivity.
2Measurement precision
If the electrode area is reduced to minimize parasitic capacitance, then detection sensitivity is improved, but the operating area decreases, lowering operability
Solution Approach 1:
By moving the shield layer to the rear surface and utilizing the substrate thickness dimension, the patent enables full-area electrode coverage on the front surface without increased parasitic capacitance. This resolves the contradiction by allowing maximum electrode area for both high sensitivity and full operability.
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 reduces parasitic capacitance and enhances EMI prevention without decreasing the electrode area, thus maintaining detection sensitivity and operability.
Implementation Method 1
a shield layer formed on a rear surface of the substrate and into a shield pattern corresponding to the predetermined pattern of the electrode layer
Implementation Method 2
an electrode layer formed on a front surface of the substrate in a predetermined pattern comprising electrodes to be touched so as to detect an electrostatic capacitance
Data Source
AI summary
An electrostatic capacitance detection device includes a substrate having a predetermined thickness, an electrode layer formed on a front surface of the substrate in a predetermined pattern including electrodes to be touched so as to detect an electrostatic capacitance and wirings drawn from the electrodes, and a shield layer formed on a rear surface of the substrate and into a shield pattern corresponding to the predetermined pattern of the electrode layer. The shield pattern of the shield layer is formed surrounding the electrodes without overlapping with the electrodes, surrounding the wirings, and between the wirings when viewed in the thickness direction of the substrate.