Piezoelectric Actuator Segmentation for Inkjet Durability
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Solution Overview
Problem
Existing liquid-droplet jetting apparatuses face challenges in durability and power consumption, particularly when performing pulling ejection, and face difficulties in densely arranging pressure chambers due to limitations in wiring connectivity and electrostatic capacitance.
Innovation Solution
A liquid-droplet jetting apparatus with a piezoelectric actuator that includes a piezoelectric layer extending from one edge of the pressure chamber, an individual electrode, and a common electrode, where the length of the piezoelectric layer is less than half the pressure chamber's length, allowing for efficient volume change and reduced electric potential difference usage, and a surface with insulating properties for wiring formation, enabling dense arrangement of pressure chambers and improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the piezoelectric layer is extended to cover the entire pressure chamber for effective liquid ejection, then the ejection performance is improved, but the durability of the piezoelectric layer deteriorates due to continuous electric field application in pulling ejection
Solution Approach 1:
The piezoelectric layer is segmented into multiple regions with different lengths extending from the edge of the pressure chamber. Specifically, the piezoelectric layer has a first region with length L1 and a second region with length L2, where L1 < L2. This segmentation allows different portions of the piezoelectric layer to serve different functions: the longer region provides sufficient ejection performance while the shorter region reduces stress concentration and improves durability during pulling ejection operations.
2Productivity
If pressure chambers are arranged densely to increase productivity, then the output is improved, but the wiring connectivity becomes difficult due to limited space and excessive electrostatic capacitance
Solution Approach 1:
The piezoelectric layer is designed with non-uniform local properties by extending it to different lengths from the pressure chamber edge. This local quality variation optimizes the electrostatic capacitance distribution, allowing dense pressure chamber arrangement while maintaining acceptable total capacitance values. The shorter extension length in certain regions reduces the capacitive load, facilitating wiring connectivity even in high-density configurations.
3Quantity of substance
If the piezoelectric layer is made longer to increase the volume change of the pressure chamber, then the liquid discharge amount is improved, but the electric potential difference required increases leading to higher power consumption
Solution Approach 1:
The piezoelectric layer extends partially from the edge of the pressure chamber rather than covering the entire chamber. The extension length is optimized to provide sufficient volume change for adequate liquid discharge without being excessively long. This partial action approach achieves the necessary liquid discharge amount while minimizing the electric potential difference required, thereby reducing power consumption compared to a full-coverage design.
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 enhances the durability of the piezoelectric layer, reduces power consumption, and allows for high-density arrangement of pressure chambers and wiring, preventing excessive electrostatic capacitance and energy loss.
Implementation Method 1
a piezoelectric layer arranged at an area overlapping with the pressure chamber such that the piezoelectric layer is extended in a predetermined direction from one edge of the pressure chamber in the predetermined direction
Data Source
AI summary
An ink-jet head includes a channel unit having pressure chambers; and a piezoelectric actuator which includes a vibration plate having an electroconductive substrate and an insulating layer, a piezoelectric layer arranged in an area overlapping with the pressure chamber, and a common electrode and an individual electrode formed on the piezoelectric layer. A recess is formed in an area overlapping with the pressure chamber. A wiring connected to the individual electrode is formed on the upper surface of the vibration plate in an area in which the piezoelectric layer is not formed. Accordingly, there is provided a liquid-droplet jetting apparatus and a liquid transporting apparatus having an improved durability, requiring a less electric power consumption, capable of performing a pulling ejection, and in which a wiring can be performed highly densely.