Recessed Wiring in Liquid Ejection Heads for Airtight Sealing
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Solution Overview
Problem
Inkjet printheads with wiring members connected at only one side suffer from reduced airtightness when capped, leading to increased ink evaporation due to level differences, and existing solutions either require additional costly components or unnecessary wiring.
Innovation Solution
A liquid ejection head design featuring a recessed portion for the wiring member, aligned with a reference surface and mounting region, reduces the level difference and enhances airtightness by integrating the wiring member within the recessed area, eliminating the need for additional components and minimizing cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wiring member is disposed at the periphery of the recording element substrate to surround it, then the airtightness inside the cap can be held well, but the cost increases due to unnecessary wiring members at portions where electrical connection is not needed
Solution Approach 1:
The surface is segmented into three distinct regions: a reference surface for cap contact, a mounting region for the recording element substrate, and a recessed portion for the wiring member. This segmentation allows the wiring member to be isolated in a dedicated area, achieving airtightness without requiring wiring around the entire periphery of the recording element substrate.
Solution Approach 2:
The wiring member is placed in a recessed portion that is recessed relative to the reference surface, utilizing the vertical dimension to separate the wiring member from the cap contact surface. This dimensional arrangement allows the cap to contact only the reference surface and mounting region, ensuring airtightness while minimizing wiring placement.
2Device complexity
If the wiring member is electrically connected at only one side of the recording element substrate, then the cost is reduced by eliminating unnecessary wiring, but the airtightness decreases due to level difference between the wiring member and the surface
Solution Approach 1:
Different regions of the surface are assigned different functions with different height levels: the reference surface is at a higher level for cap contact, while the recessed portion is at a lower level to accommodate the wiring member. This local quality differentiation allows the wiring member to be positioned at a lower height, eliminating level differences that would compromise airtightness.
Solution Approach 2:
The wiring member is nested within the recessed portion, which is itself nested within the overall housing structure. This nested arrangement allows the wiring member to be contained within a dedicated space that is recessed relative to the reference surface, ensuring that the wiring member does not protrude and compromise the airtight seal when the cap contacts the reference surface.
3Reliability
If a member constituting a continuous surface is provided to compensate for the level difference, then the airtightness can be maintained, but the manufacturing cost increases due to additional processes and adhesives
Solution Approach 1:
The recessed portion is integrated into the housing as a single molded feature, combining the functions of the housing and the surface structure into one component. This eliminates the need for separate members to constitute the continuous surface, reducing manufacturing steps and eliminating the need for additional adhesives while maintaining airtightness.
Solution Approach 2:
The recessed portion structure automatically provides the necessary level difference compensation and airtight sealing function through its own geometry, without requiring additional components or complex assembly processes. The housing itself serves the dual purpose of containing the wiring member and providing the reference surface for cap contact.
Data Source
AI summary
A liquid ejection head includes a housing having a first outer surface; a liquid ejection substrate disposed at a first portion of the first outer surface and having ejection ports for ejecting liquid; and a wiring member disposed on a second portion of the first outer surface so as to be next to the liquid ejection substrate and electrically connected to the liquid ejection substrate. The ejection ports are covered by a cap that is in contact with the wiring member and a portion, except the second portion, of the first outer surface around the liquid ejection substrate; and the second portion is recessed relative to the portion, except the second portion, of the first outer surface around the liquid ejection substrate.