Pitch Conversion Member Layout for Air-Bubble-Resistant Inkjet Heads
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Solution Overview
Problem
Existing liquid ejection heads face issues with air bubble entrapment due to increased pitch conversion rates, leading to defective liquid ejection, particularly in configurations with fan-out channels having large tilt angles, which hinder quick air bubble release.
Innovation Solution
A liquid ejection head design featuring a pitch conversion member with overlapping first and second openings in the print element substrate and channel member, respectively, where the distance between closest openings in the second array direction is shorter than in the first, facilitating efficient air bubble release and reducing defective ejections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fan-out channels with large tilt angles are used for pitch conversion, then array pitch conversion is achieved, but air bubble release is hindered
Solution Approach 1:
The pitch conversion member is divided into multiple through-holes arranged in arrays, with first openings on the first surface and second openings on the second surface. This segmentation allows air bubbles to be released through multiple discrete pathways rather than being trapped in continuous fan-out channels, while maintaining the required pitch conversion functionality.
Solution Approach 2:
The invention transitions from planar fan-out channels to three-dimensional through-holes penetrating the pitch conversion member. The through-holes extend from the first surface through the thickness to the second surface, creating vertical pathways that facilitate air bubble escape in the thickness direction while maintaining the horizontal pitch conversion arrangement.
2Manufacturing precision
If pitch conversion rate is increased to match smaller print element substrate channels, then array pitch conversion is improved, but air bubble entrapment increases
Solution Approach 1:
The through-holes are pre-formed in the pitch conversion member during manufacturing, creating ready-made air bubble escape pathways before liquid ejection begins. This preliminary action ensures that air bubbles generated during high-rate pitch conversion can immediately find escape routes through the pre-existing through-hole network rather than being trapped.
Solution Approach 2:
The pitch conversion member with through-holes acts as an intermediary structure between the channel member and print element substrate. The through-holes serve as intermediate pathways that connect the higher-pitch channels to the lower-pitch substrate channels while providing dedicated air bubble escape routes, mediating between the conflicting requirements of high pitch conversion rate and reliable air bubble release.
3Reliability
If through-holes with overlapping openings are used, then air bubble release is facilitated, but manufacturing complexity increases
Solution Approach 1:
The through-holes in the pitch conversion member serve multiple functions simultaneously: they convert the array pitch from the channel member to the print element substrate, and they provide air bubble escape pathways. This multi-functionality reduces the need for separate components for each function, thereby managing overall device complexity while achieving reliable air bubble release.
Solution Approach 2:
The first openings and second openings are nested within the same through-hole structure, with the through-hole penetrating the entire thickness of the pitch conversion member. The first openings on the first surface and second openings on the second surface are aligned such that they form continuous pathways through the member, creating a nested arrangement that facilitates air bubble release while maintaining compact geometry.
Data Source
AI summary
A liquid ejection head that is more reliable than conventional heads includes a pitch conversion member. The pitch conversion member includes a plurality of first openings respectively connected to a plurality of first channels, and a plurality of second openings respectively connected to a plurality of second channels. A region where a plurality of the first openings are provided and a region where a plurality of the second openings are provided overlap as viewed from a penetration direction of the first openings and the second openings. A first distance in a second array direction between the two first openings closest to each other in the second array direction intersecting a first array direction is shorter than a second distance in the second array direction between the two second openings closest to each other in the second array direction.