Piezoelectric Actuator Lower Electrode Stiffness
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Solution Overview
Problem
Piezoelectric elements in actuator devices experience a decrease in displacement characteristics due to plastic deformation caused by repeated strain, leading to a loss of malleability in the lower electrode, especially when made of soft materials like pure platinum.
Innovation Solution
Incorporating a lower electrode with a Young's modulus of 200 GPa or larger, made from alloys containing platinum, oxygen, and other metals such as titanium or lead, which maintains stiffness and conductivity, preventing plastic deformation and maintaining displacement characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a soft material like pure platinum is used for the lower electrode, then the lower electrode has excellent malleability and conductivity, but the piezoelectric element suffers from plastic deformation and loss of displacement characteristics due to repeated strain
Solution Approach 1:
The invention changes the physical parameter of the lower electrode material by controlling the grain size to be 10 μm or smaller through specific sintering conditions. This parameter change transforms the material properties, enabling the electrode to withstand repeated strain without plastic deformation while maintaining conductivity, thus resolving the contradiction between reliability and strength.
Solution Approach 2:
The invention uses a composite structure where the lower electrode is formed by sintering platinum particles with controlled grain size. This composite approach combines the conductivity of platinum with the structural integrity provided by the fine-grained sintered structure, preventing plastic deformation while maintaining electrical properties.
2Reliability
If the lower electrode is made stiff to prevent plastic deformation, then displacement characteristics are maintained, but the ease of manufacture and flexibility in forming the electrode may be reduced
Solution Approach 1:
The invention changes the manufacturing parameter by controlling the sintering temperature and time to achieve specific grain sizes. This parameter control enables the formation of a stiff, deformation-resistant electrode structure through a standardized sintering process, maintaining ease of manufacture while achieving the desired mechanical properties.
Solution Approach 2:
The invention replaces mechanical forming methods with a sintering-based formation process. By depositing platinum particles and sintering them under controlled conditions, the electrode acquires its final stiff structure without requiring complex mechanical forming operations, thus maintaining manufacturing simplicity while achieving the required mechanical strength.
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 use of a stiff lower electrode with a Young's modulus of 200 GPa or larger in piezoelectric elements prevents plastic deformation and maintains excellent displacement characteristics, even after repeated drives, enhancing the durability and reliability of liquid-jet heads.
Implementation Method 1
a piezoelectric layer made of a piezoelectric material exhibiting an electromechanical transduction function
Data Source
AI summary
Disclosed is an actuator device that includes a piezoelectric element provided as being freely displaceable on a substrate. The piezoelectric element includes a lower electrode, a piezoelectric layer and an upper electrode. In the actuator device, the Young's modulus of the lower electrode is not less than 200 GPa.