Piezoelectric Device Laminated Electrode Ultrasonic Sensor
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Solution Overview
Problem
Ultrasonic sensors face challenges in improving receiving properties due to the trade-off between deformation efficiency and residual polarization, where using iridium as an electrode material enhances deformation efficiency but reduces residual polarization, while platinum maintains polarization but limits receiving properties due to lower tensile stress.
Innovation Solution
A piezoelectric device with a laminated structure of platinum and iridium electrodes, where the platinum layer is in contact with the piezoelectric layer to increase residual polarization and the iridium layer extends beyond the piezoelectric element to apply tensile stress in both X and Y directions, reducing initial deflection and preventing electrode separation during thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If iridium is used as electrode material, then deformation efficiency is improved, but residual polarization is reduced
Solution Approach 1:
The patent employs a composite electrode structure consisting of a platinum layer and an iridium layer. The platinum layer contacts the piezoelectric layer to preserve residual polarization, while the iridium layer extends beyond the piezoelectric element to provide tensile stress for improved deformation efficiency. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The electrode is divided into two distinct layers with different functions: the platinum layer (first layer) maintains electrical contact with the piezoelectric layer to preserve polarization, while the iridium layer (second layer) extends outward to apply tensile stress. This segmentation allows each material to optimize its specific function without compromising the other.
2Quantity of substance
If platinum is used as electrode material, then residual polarization is maintained, but receiving properties are limited due to lower tensile stress
Solution Approach 1:
The composite electrode structure combines platinum's ability to maintain residual polarization with iridium's ability to provide high tensile stress. The platinum layer ensures polarization preservation while the iridium layer enhances deformation efficiency, thereby improving receiving properties without sacrificing polarization.
Solution Approach 2:
By segmenting the electrode into platinum and iridium layers, the patent allows the platinum layer to maintain polarization while the iridium layer provides the necessary tensile stress for improved receiving properties, resolving the limitation of using platinum alone.
3Power
If initial deflection is suppressed to ACT surface side by tensile stress, then receiving properties are improved, but electrode separation may occur during thermal treatment
Solution Approach 1:
The composite structure of platinum and iridium layers provides both the tensile stress needed to suppress initial deflection and the adhesion strength to prevent electrode separation during thermal treatment. The combination of materials ensures both mechanical performance and structural reliability.
Solution Approach 2:
The segmented electrode structure allows the platinum layer to provide strong adhesion to the piezoelectric layer, preventing separation during thermal processing, while the iridium layer extends outward to provide the necessary tensile stress for suppressing initial deflection and improving receiving properties.
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 enhances receiving properties by increasing residual polarization and deformation efficiency while suppressing initial deflection, leading to improved ultrasonic sensor performance.
Implementation Method 1
an ultrasonic sensor using electromechanical transformation characteristics of a piezoelectric element is provided. In the ultrasonic sensor, an ultrasonic wave (transmitting ultrasonic wave) is transmitted by driving the piezoelectric element by supplying electric signals to the piezoelectric element.
Implementation Method 2
the piezoelectric element receives the ultrasonic wave (reflected ultrasonic wave) which is reflected from a measurement object, thereby driving the piezoelectric element and obtaining the electric signals.
Implementation Method 3
the Ir has characteristics of great tensile stress. By using the characteristics, the initial deflection of the vibrating plate can be set to the ACT surface side instead of the CAV surface side by the tensile stress.
Data Source
AI summary
A piezoelectric device includes a substrate with a cavity, a vibrating plate which is provided on the substrate so as to block an opening surface of the cavity, and a piezoelectric element which is provided on a surface of the vibrating plate opposite to the cavity, including a first electrode, a piezoelectric layer, and a second electrode, in which the second electrode has a laminated structure including a Pt layer (lower layer side electrode) and an Ir layer (upper layer side electrode), in which the Pt layer is in contact with the piezoelectric layer, and in which, if it is assumed that two directions which are parallel to a surface of the substrate and mutually perpendicular are defined as an X direction and a Y direction, the Ir layer is extended to an outside of the cavity at least in the X direction on an X-Y plane view.