Capacitor Structure With Mismatched Poisson Ratios For Strain Stability
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Solution Overview
Problem
Flexible display devices face challenges in maintaining constant capacitance when subjected to external strain, leading to potential malfunction in capacitive touch panels and other applications due to changes in the shape of the capacitor structure.
Innovation Solution
A capacitor structure is designed with a first and second substrate and a dielectric layer, where the Poisson's ratio of the substrates differs from that of the dielectric layer, minimizing changes in capacitance under strain by controlling length variations in specific directions, thereby maintaining constant capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional capacitor structure is used in flexible display devices, then the device can be bent and folded for portability, but the capacitance changes when external strain is applied causing malfunction
Solution Approach 1:
The patent changes the Poisson's ratio parameter of the dielectric layer by selecting materials with different Poisson's ratios than the substrates. This parameter change allows the dielectric layer to compensate for dimensional changes in the substrates under strain, maintaining constant capacitance while preserving flexibility
Solution Approach 2:
The patent uses composite material structure with substrates and dielectric layer having different Poisson's ratios. The dielectric layer is formed from materials such as PDMS, PU, or silicone rubber with specific Poisson's ratios that differ from the substrate materials, creating a composite structure that maintains capacitance stability under deformation
2Reliability
If the Poisson's ratio of substrates and dielectric layer is made different, then capacitance remains constant under strain, but material selection and manufacturing complexity increase
Solution Approach 1:
The patent systematically addresses material selection complexity by providing specific Poisson's ratio ranges for dielectric layer materials (0.45-0.55 for PDMS, 0.28-0.32 for PU, 0.48-0.52 for silicone rubber). These parameter specifications guide material selection while ensuring capacitance stability, reducing the practical complexity despite the theoretical variety of material combinations
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
The capacitor structure effectively maintains constant capacitance even when exposed to external strain, preventing malfunctions in flexible devices and ensuring reliable operation of touch sensing and display functions.
Implementation Method 1
a Poisson's ratio of the first substrate or the second substrate is different from that of the dielectric layer
Data Source
AI summary
A capacitor structure includes: a first substrate having a first electrode part provided on one surface thereof; a second substrate having a second electrode part provided on a surface thereof, which faces the first substrate; and a dielectric layer provided between the first substrate and the second substrate, wherein a Poisson's ratio of the first substrate or the second substrate is different from a Poisson's ratio of the dielectric layer. The capacitor structure has a substantially constant capacitance even when the capacitor structure is exposed to external strain.