Liquid Ejection Head Ceramic Throttles for Meniscus Control
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Solution Overview
Problem
Existing ink jet heads face challenges in achieving high productivity and consistent droplet ejection due to ink overshooting and meniscus swelling, particularly with large droplets, and the formation of gaps between cover members and substrates complicates insulation and protection of electrode wiring.
Innovation Solution
A liquid ejection head design with a cover member that includes throttle portions to increase fluid resistance and a method for manufacturing the head that ensures insulation of electrode wiring by using a capillary-action adhesive to fill gaps between the cover member and substrate, forming a protective layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross section of the pressure chamber is reduced to increase fluid resistance, then meniscus swelling is reduced and ejection stability is improved, but it becomes difficult to ensure throttle accuracy when using photosensitive resin at the inlet and outlet
Solution Approach 1:
A cover member made of ceramic material is introduced as an intermediary component to form the throttle portions at the inlet and outlet of the pressure chamber. This ceramic cover member provides precise flow path resistance control through its material properties and structured design, resolving the difficulty of ensuring throttle accuracy when using photosensitive resin while maintaining reduced meniscus swelling and improved ejection stability
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 throttle accuracy is improved, but gaps may form between the cover member and substrate making electrode wiring insulation difficult
Solution Approach 1:
An insulating material is introduced as an intermediary substance filled in the gaps between the ceramic cover member and the substrate. This insulating material serves dual purposes: it provides electrical insulation to protect the electrode wiring from short circuits, and it seals the gaps to maintain the structural integrity of the flow path, thereby resolving the insulation complexity issue while preserving the throttle accuracy provided by the ceramic cover member
3Productivity
If one drive column is shared by two pressure chambers to increase productivity, then device complexity is reduced, but only 1/3 of the pressure chambers can be driven at the same time limiting ejection speed
Solution Approach 1:
The drive columns are segmented into independent units, with each pressure chamber equipped with its own dedicated drive column. This segmentation allows all pressure chambers to be driven simultaneously at full speed, eliminating the limitation of the shared drive column configuration where only 1/3 of chambers could operate at once, thereby significantly increasing ejection speed and productivity while maintaining manageable device complexity through modular design
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 and ensuring reliable insulation of electrode wiring, allowing for high-frequency operation without short circuits.
Implementation Method 1
a method for manufacturing the liquid ejection head that ensures insulation of electrode wiring by using a capillary-action adhesive to fill gaps between the cover member and substrate
Data Source
AI summary
A liquid ejection head includes nozzles through which liquid is ejected, pressure chambers communicating with the nozzles, volumes of the chambers being varied to eject the liquid, a substrate including an electrode on a surface of the substrate, an actuator 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 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.