Liquid Ejection Head Throttle Structure for Stable Droplet Output
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Solution Overview
Problem
Ink jet heads face challenges in achieving high productivity and consistent droplet ejection due to ink overshoot and meniscus swelling, particularly with large droplets, and existing methods for increasing fluid resistance at the pressure chamber inlets are inaccurate and difficult to implement.
Innovation Solution
A liquid ejection head design with a cover member that forms a throttle portion at the pressure chamber inlet and outlet, combined with an insulating adhesive filling a gap between the cover member and substrate to ensure accurate fluid resistance and insulation of electrode wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fluid resistance at the pressure chamber inlet is increased to reduce meniscus swelling, then ejection stability is improved, but manufacturing precision is difficult to ensure when using photosensitive resin
Solution Approach 1:
The patent changes the material parameter from photosensitive resin to ceramic for the cover member, which provides better dimensional stability and manufacturing precision. The ceramic material allows for accurate formation of the throttle portion at the pressure chamber inlet while maintaining the required fluid resistance to control meniscus swelling.
2Manufacturing precision
If a ceramic plate-shaped cover member is joined to the inlet and outlet of the pressure chamber to generate flow path resistance, then manufacturing precision is improved, but gaps may form between the cover member and substrate
Solution Approach 1:
The patent introduces an insulating adhesive as an intermediary substance between the ceramic cover member and the substrate. This adhesive fills the gap that forms during joining, providing both mechanical bonding and electrical insulation protection for the electrode wiring located beneath the cover member.
3Reliability
If an insulating film is sprayed onto the electrode formation surface, then insulation is provided, but the cover member acts as eaves and prevents proper insulation of electrode wiring below
Solution Approach 1:
The insulating adhesive serves as a mediator that is applied first to fill the gap and protect the electrode wiring before the cover member is positioned. This eliminates the problem of the cover member acting as eaves that would prevent proper insulation application.
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 enhances ejection stability and speed by reducing meniscus swelling, allowing for high-frequency operation with improved printing quality and reduced risk of short circuits.
Implementation Method 1
an insulating adhesive that fills a gap between the cover member and the substrate
Data Source
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AI summary
A liquid ejection head includes nozzles (28) through which liquid is ejected, pressure chambers (31) communicating with the nozzles, volumes of the chambers being varied to eject the liquid, a substrate (21) including an electrode on a surface of the substrate, an actuator (22) connected to the electrode and configured to vary the volumes, the actuator having a first side surface connected to the surface of the substrate, a first cover member (24) that covers the first side surface and includes openings each facing one of the chambers, the openings having larger fluid resistance than the chambers, an insulating material between the surface of the substrate and the first cover member, and an insulating film that covers the electrode on the substrate.