Piezoelectric Element Crack Suppression via Layer Extension
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Solution Overview
Problem
Existing piezoelectric elements in liquid ejecting heads face challenges in suppressing cracking and stress concentration at the border between active and non-active units, which can lead to deformation and malfunction.
Innovation Solution
A piezoelectric element configuration with a support body allowing flexural deformation in one region and inhibiting it in another, featuring a metal layer and adhesion layer extension beyond the electrode layers, and a protective film between the adhesion layer and piezoelectric layer to regulate motion and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the piezoelectric layer is extended beyond the electrode layers to increase rigidity at the border position, then the resistance to cracking is improved, but the structural complexity increases
Solution Approach 1:
The piezoelectric layer is extended in the longitudinal dimension beyond the electrode layers, creating an overlapping region that provides rigidity support at the border position without requiring additional structural elements. This dimensional extension resolves the contradiction by achieving crack resistance through spatial arrangement rather than structural complexity.
Solution Approach 2:
The invention creates a composite structure where the piezoelectric layer and electrode layers overlap and work together as an integrated system. The piezoelectric layer serves dual functions: generating pressure changes in the active region and providing rigidity support in the extended overlapping region, while the electrode layers provide both electrical function and structural support through their overlap.
2Stability of the object's composition
If the piezoelectric layer is extended beyond the electrode layers, then the rigidity at the border position is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention divides the piezoelectric layer into functionally distinct regions: an active unit portion that generates pressure changes and a non-active unit portion that provides rigidity support. This segmentation allows each region to be optimized for its specific function while simplifying the manufacturing process by treating them as distinct functional zones within a single continuous layer.
Solution Approach 2:
The extended piezoelectric layer serves multiple functions simultaneously: it generates pressure changes in the active region, provides rigidity support at the border position through its extension, and maintains structural integrity throughout. This multi-functionality reduces manufacturing complexity by eliminating the need for separate components for each function.
3Reliability
If the metal layer and adhesion layer are extended beyond the electrode layers, then the motion regulation at the border is improved, but the device complexity increases
Solution Approach 1:
The adhesion layer serves as an intermediary between the metal layer and the piezoelectric layer, providing both mechanical bonding and motion regulation functionality. By extending the adhesion layer beyond the electrode layers, it acts as a mediator that regulates the motion of the piezoelectric layer at the border position while maintaining structural integrity, thus improving reliability without significantly increasing device complexity.
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 effectively prevents excessive deformation and stress concentration, enhancing the reliability of the piezoelectric element, liquid ejecting head, and apparatus by reliably suppressing cracking and improving overall performance.
Implementation Method 1
a piezoelectric element which causes a pressure change to liquid in a pressure chamber. The piezoelectric element is configured by stacking, for example, a lower electrode layer which functions as an individual electrode which is provided in each pressure chamber, a piezoelectric layer such as lead zirconate titanate (PZT), and a higher electrode layer which functions as a common electrode which is common to a plurality of the pressure chambers
Data Source
AI summary
A piezoelectric element includes a vibrating plate which is formed of a first region in which a flexural deformation is allowed, and a second region in which the flexural deformation is inhibited. A piezoelectric element main body includes a lower electrode layer, a piezoelectric layer, and a higher electrode layer on the first region of the vibrating plate. A common metal layer is stacked on the higher electrode layer. A part of the piezoelectric element main body is extended to the second region, and an end portion of the piezoelectric layer is extended to the outside of an end portion of the higher electrode layer on the same side.