Piezoelectric Actuator Gap Design for Electrode Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In ink-jet printers, the piezoelectric displacement is suppressed and the upper electrode is prone to breakage due to stress concentration at the boundary between the piezoelectric member above the pressure chamber and the side wall, especially when the thickness of the piezoelectric member is large, making it difficult to draw out the upper electrode effectively.
Innovation Solution
A piezoelectric actuator configuration where the piezoelectric member is separated by a gap portion above the boundary surface between the pressure chamber and the side wall, allowing the upper electrode to be drawn out over the gap, reducing stress concentration and preventing breakage, and enabling easy electrode formation even with thick piezoelectric members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the piezoelectric member is continuous over the area above the pressure chamber and the area above the side wall, then it is easy to form the upper electrode by evaporation or sputtering, but stress concentration occurs at the boundary, causing cracks and electrode breakage
Solution Approach 1:
The piezoelectric member is divided into two separate regions: a first piezoelectric member above the pressure chamber and a second piezoelectric member above the side wall, with a gap portion between them. This segmentation prevents stress concentration at the boundary while maintaining ease of electrode formation on each separate region.
2Ease of operation
If the piezoelectric member above the side wall is present, then the upper electrode can be drawn out easily, but the piezoelectric displacement of the member above the pressure chamber is suppressed
Solution Approach 1:
By segmenting the piezoelectric member with a gap portion, the second piezoelectric member above the side wall no longer mechanically constrains the first piezoelectric member above the pressure chamber. This allows the first member to achieve full piezoelectric displacement while still enabling electrode drawing out through the gap region.
3Strength
If the thickness of the piezoelectric member is large, then the electrode can be formed more robustly, but it becomes difficult to draw out the upper electrode along the side surface
Solution Approach 1:
Instead of drawing the electrode along the vertical side surface (one-dimensional path), the electrode is drawn out through the gap portion, utilizing the horizontal space above the boundary surface. This dimensional change allows easy electrode extraction even with thick piezoelectric members.
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 avoids a decrease in piezoelectric displacement, prevents upper electrode breakage, and allows for reliable drawing out of the upper electrode, reducing power consumption and increasing the life of the ink-jet head while enhancing the actuator's performance as a pump or sensor.
Implementation Method 1
when voltage is applied to the upper electrode and the lower electrode, the expansion and contraction of the piezoelectric member cause piezoelectric distortion (piezoelectric displacement)
Data Source
AI summary
In a piezoelectric actuator (1) that vibrates a diaphragm (12) provided on a pressure chamber (21) formed in a substrate (11) toward the pressure chamber (21), a lower electrode (13), a piezoelectric member (14) and an upper electrode (15) sequentially stacked on the diaphragm (12) are provided, on a part of the piezoelectric member (14) above the side wall of the pressure chamber (21), an upper electrode drawing portion (15a) drawn out from the upper electrode (15) above the pressure chamber (21) is formed and under the upper electrode drawing portion (15a), the piezoelectric member (14) is separated by a gap portion (S) above a boundary surface between the side wall (21a) of the pressure chamber (21) and the pressure chamber (21) in the substrate (11).