Liquid Ejection Head Recessed Portion Asymmetry
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Solution Overview
Problem
The variation in pressures from components like a wiper and a mask onto the ejection face of liquid ejection heads can cause damage to the ink repellent layer and make it difficult to remove excess portions, leading to ejection failures.
Innovation Solution
The ejection face is designed with recessed portions where the central position of the bottom portion is positioned relative to the ejection opening such that the large-and-small relationship of specific distances between adjacent recessed portions is maintained, allowing for uniform pressure distribution and accurate excess portion removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If recessed portions are formed in the ejection face to protect the ink repellent layer, then the ink repellent layer is protected from damage, but pressure variation occurs on the ejection face causing damage to the ink repellent layer at peripheries of ejection openings
Solution Approach 1:
The invention positions the bottom portion of each recessed portion asymmetrically relative to the ejection opening, specifically offsetting it toward one side. This asymmetric positioning creates a geometric relationship where the distances from the ejection opening center to the adjacent recessed portion boundaries follow a specific pattern (d1 < d2), which compensates for pressure variations and ensures uniform pressure distribution across the ejection face during wiper operation.
2Manufacturing precision
If mask pressure is increased to prevent mask entry into ejection openings, then masking accuracy is improved, but the mask cannot be properly positioned and excess portion removal becomes unreliable
Solution Approach 1:
The asymmetric positioning of the recessed portion bottom relative to the ejection opening creates a geometric constraint that prevents the mask from entering the ejection openings while maintaining proper mask contact with the ejection face. This geometric relationship (d1 < d2) ensures that even when mask pressure is applied, the mask cannot penetrate into the ejection openings, allowing for reliable excess portion removal during the masking process.
3Productivity
If wiper pressure is increased to ensure complete wiping of the ejection face, then cleaning effectiveness is improved, but excessive pressure is applied to certain areas causing damage to the ink repellent layer
Solution Approach 1:
The invention employs asymmetric positioning of the recessed portion bottom to distribute wiper pressure uniformly across the ejection face. By offsetting the bottom portion toward one side and creating the specific geometric relationship (d1 < d2), the design ensures that no single area receives excessive pressure concentration, allowing complete wiping effectiveness while protecting the ink repellent layer from damage.
Data Source
AI summary
A liquid ejection head has recessed portions are formed in an ejection face, such that a distance d1 is between a center of an ejection opening in one recessed portion and an other-side side face of another recessed portion adjacent thereto on one side, where a distance d2 is between the center and a one-side face of another recessed portion adjacent to the one recessed portion on the other side, and where a distance x1 is between the center and a one-side side face of the one recessed portion, and a distance x2 is between the center and an other-side side face thereof. A central position of a bottom portion of the one recessed portion is positioned relative to the center, such that a relationship between distance d1 and distance d2 is the same as a relationship between distance x1 and distance x2.