Liquid Ejecting Head Supply Flow Path Bubble Discharge
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Solution Overview
Problem
The existing liquid ejecting heads face challenges in effectively discharging bubbles from the supply flow path, particularly due to the sagging shape of the inlet portion, which affects the ejection of liquid droplets and requires improved bubble suppression to maintain printing quality.
Innovation Solution
A liquid ejecting head design featuring a multilayer substrate with a supply flow path having a narrower inlet portion and inclined portions, which facilitates better bubble discharge during cleaning, improving the flow of liquid and reducing residual bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the inlet portion of the supply flow path has a sagging shape (expanded wall surface), then the liquid can be supplied smoothly from the common liquid chamber to the pressure chambers, but bubbles adhering to the wall surface become difficult to discharge during cleaning
Solution Approach 1:
The supply flow path is designed with different cross-sectional areas at different locations: a first cross-sectional area at the inlet portion and a second cross-sectional area at another portion, where the first area is smaller than the second area. This local variation in geometry creates a flow acceleration effect that enables bubbles to be discharged from the inlet portion while maintaining smooth liquid supply elsewhere in the flow path.
Solution Approach 2:
The invention changes the geometric parameters of the supply flow path by varying the cross-sectional area along the flow direction. Specifically, the cross-sectional area increases from the inlet portion toward the pressure chamber, creating a gradual expansion that promotes bubble detachment and discharge while ensuring continuous liquid flow.
2Ease of operation
If the inlet portion of the supply flow path is expanded (sagging shape), then liquid flow is facilitated, but residual bubbles affect the ejection of liquid droplets
Solution Approach 1:
The supply flow path incorporates a localized geometric feature where the cross-sectional area varies along the flow direction. The inlet portion has a smaller cross-sectional area that gradually transitions to a larger area, creating a controlled expansion zone that facilitates bubble discharge while maintaining smooth liquid flow in the broader flow path.
Solution Approach 2:
Instead of expanding the inlet portion as in conventional designs, the invention uses a contraction-expansion profile where the inlet has a smaller cross-section that opens up downstream. This inverted approach to flow path geometry achieves bubble removal by creating a flow acceleration zone that detaches bubbles from the wall surface.
3Device complexity
If a conventional supply flow path design is used, then the structure is simple, but bubble discharge during cleaning is ineffective
Solution Approach 1:
The supply flow path maintains overall structural simplicity while incorporating a specific local geometric feature: a variation in cross-sectional area where the inlet portion has a smaller area than downstream portions. This localized design modification enables effective bubble discharge without significantly complicating the overall flow path structure.
Data Source
AI summary
A liquid ejecting head includes a nozzle plate, a multilayer substrate, and a pressure chamber substrate. The multilayer substrate includes a liquid chamber wall portion. The liquid chamber wall portion has a first wall surface facing a common liquid chamber. The multilayer substrate has a supply flow path which has an inlet portion coupled to the first wall surface and via which the common liquid chamber communicates with the first pressure chamber. When a direction from the common liquid chamber toward the first pressure chamber is defined as a first direction, and a direction intersecting the first direction is defined as a second direction, the supply flow path includes a first portion having a first width in the inlet portion and a second portion having a second width, in a first cross section along the first direction and the second direction. The first width is narrower than the second width.