Multilayer Piezoelectric Element Insulating Resistance Layer Design
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Solution Overview
Problem
Conventional multilayer piezoelectric elements face characteristic degradation due to the pyroelectric effect, particularly from temperature changes, leading to polarization degree deterioration and potential short circuits from uneven resistance values in external materials, making it difficult to balance migration prevention and resistance adjustment.
Innovation Solution
A multilayer piezoelectric element design featuring a piezoelectric active area covered by an insulating layer and a resistance layer isolated from the active area, connecting internal electrodes in inactive areas with a lower electrical resistance, preventing polarization degree decline and short circuits while allowing for thinning of the piezoelectric body layer and improved manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conducting particles are dispersed in exterior material to inhibit polarization degree decrease, then pyroelectric effect resistance is improved, but local low resistance areas form causing short circuits between internal electrodes
Solution Approach 1:
The exterior material is segmented into multiple functional layers: an insulating layer that covers the piezoelectric active area to prevent short circuits, and a resistance layer with conducting particles that connects internal electrodes to inhibit polarization degree decrease. This segmentation allows each layer to perform its specific function without interfering with the other.
Solution Approach 2:
Different regions of the exterior material are assigned different electrical properties: the insulating layer has high resistance to prevent short circuits, while the resistance layer has lower resistance to dissipate pyroelectric charges. The resistance layer is specifically positioned in piezoelectric inactive areas where it can connect internal electrodes without interfering with the active piezoelectric function.
2Device complexity
If exterior material serves both migration prevention and resistance adjustment functions, then device complexity is reduced, but material selection and compounding ratio adjustment become difficult
Solution Approach 1:
The exterior material is divided into separate insulating layer and resistance layer, allowing each layer to be optimized for its specific function. The insulating layer focuses on migration prevention while the resistance layer focuses on resistance adjustment, making material selection and manufacturing easier.
Solution Approach 2:
The resistance layer serves dual purposes: it provides electrical connection between internal electrodes and dissipates pyroelectric charges. The insulating layer provides both physical protection and electrical insulation. This multi-functional design reduces overall device complexity while maintaining manufacturing ease.
3Volume of moving object
If distance between internal electrodes is reduced for downsizing, then element size is decreased, but short circuit risk from conducting particle aggregation increases
Solution Approach 1:
The exterior material is segmented into insulating and resistance layers, with the insulating layer providing a protective barrier that prevents short circuits even when internal electrodes are closely spaced. This allows downsizing without increasing short circuit risk.
Solution Approach 2:
The insulating layer acts as an intermediary barrier between internal electrodes, preventing direct contact and short circuits. The resistance layer serves as a mediator that provides controlled electrical connection for charge dissipation. This intermediary structure enables safe downsizing.
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 effectively inhibits pyroelectric effect-induced characteristic degradation, enables downsizing, and simplifies manufacturing by isolating the resistance layer from the active area, ensuring reliable polarization protection and preventing short circuits, while maintaining effective migration prevention at a lower cost.
Implementation Method 1
an insulating layer which covers the piezoelectric active area of a both electrodes exposure surface
Implementation Method 2
a problem such as deterioration of polarization degree due to pyroelectric effect may occur to piezoelectric element
Implementation Method 3
an resistance layer which is isolated from the piezoelectric active area by the insulating layer, is placed at the both electrodes exposure surface in order to connect at least one part of the first internal electrode in the piezoelectric inactive area and at least one part of the second internal electrode in the piezoelectric inactive area
Implementation Method 4
The piezoelectric element is an element, which mutually transforms between mechanical displacement and electric displacement by using piezoelectric effect and inverse piezoelectric effect
Implementation Method 5
The piezoelectric element is an element, which mutually transforms between mechanical displacement and electric displacement by using piezoelectric effect and inverse piezoelectric effect
Data Source
AI summary
An element body having a first and second internal electrodes exposure surface comprising a piezoelectric active area, wherein a first internal electrode faces a second internal electrode sandwiching piezoelectric body layer in-between along laminating direction, and a piezoelectric inactive area, wherein the piezoelectric body layer contacts only first or second internal electrode at one face along laminating direction, or the first internal electrodes or the second internal electrodes respectively face each other sandwiching piezoelectric body layer in-between along laminating direction, an insulating layer which covers the piezoelectric active area of the first and second internal electrodes exposure surface, and a resistance layer which is isolated from the piezoelectric active area by the insulating layer, placed at the first and second internal electrodes exposure surface connecting at least a part of the first and that of the second internal electrode in the piezoelectric inactive area and has lower electrical resistance value relative to that of the piezoelectric body layer.