Liquid Ejection Head with Lead-Gradient Crack Resistance
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Solution Overview
Problem
Existing liquid ejection heads, such as those in piezoelectric ink jet printers, suffer from cracking at the end portions of the lower electrode due to uneven lead distribution and concentration in the piezoelectric elements.
Innovation Solution
A liquid ejection head design with a piezoelectric element comprising a first electrode, a piezoelectric layer, and a second electrode, where the first electrode has a lead-containing layer with varying lead content percentages in different regions to enhance adhesion and reduce cracking, specifically with a higher lead content percentage in the center region and a lower lead content percentage at the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform lead distribution is used in the first electrode, then manufacturing is simpler, but cracking occurs at the end portions due to uneven stress distribution
Solution Approach 1:
The patent applies local quality by creating a lead-containing layer with non-uniform lead distribution within the first electrode. Specifically, the lead content is higher in the end portions and lower in the center portion, allowing each region to have optimized properties for its specific functional requirements. This gradient distribution reduces stress concentration at the ends while maintaining manufacturing feasibility through controlled deposition processes.
2Strength
If higher lead content is used throughout the first electrode, then adhesion to vibration plate improves, but stress concentration and cracking increase at end portions
Solution Approach 1:
The patent applies parameter changes by systematically varying the lead content parameter across different regions of the first electrode. The lead-containing layer is designed with higher lead concentration in the end portions and lower concentration in the center portion. This gradient parameter distribution optimizes the balance between adhesion strength (improved by lead content) and stress distribution (reduced by avoiding excessive lead at critical locations).
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 design inhibits cracking at the end portions of the first electrode, enhances adhesion between the electrode and vibration plate, and mitigates stress, thereby improving the durability and performance of the liquid ejection head.
Implementation Method 1
a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode... the piezoelectric layer is formed of a piezoelectric material containing lead as a constituent element
Data Source
AI summary
A liquid ejection head includes: a vibration plate and a piezoelectric element, having a first electrode, a piezoelectric layer, and a second electrode which are laminated in a lamination direction, the piezoelectric layer is formed of a piezoelectric material containing lead as a constituent element, the first electrode has an electrode layer and a lead-containing layer disposed between the electrode layer and the vibration plate and containing lead, and when, of two regions arranged in a crossing direction, which is a direction crossing the lamination direction, when seen in the lamination direction, a region farther away from a center of the first electrode is a first region and a region closer to the center of the first electrode is a second region, a lead content percentage in the lead-containing layer in the first region is lower than a lead content percentage in the lead-containing layer in the second region.