Liquid Ejecting Head Nozzle Design for Split Droplet Prevention
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Solution Overview
Problem
The existing liquid ejecting heads with a two-stage nozzle shape, where arcs partially overlap, cause liquid droplets to be ejected in a split state, leading to potential issues with droplets landing on a medium in a split state.
Innovation Solution
A liquid ejecting head with a nozzle design featuring a first external shape comprising a first arc, a second arc, and a connecting portion, where the second distance between the centers of the arcs is greater than the diameter of the arcs, and the connecting portion's width is less than the arcs' diameter, reducing the likelihood of split droplet ejection by utilizing capillary forces to unite the droplets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-stage nozzle shape with partially overlapping arcs is used, then liquid is less likely to remain in the nozzle, but liquid droplets are ejected in a split state
Solution Approach 1:
The nozzle internal shape is divided into multiple sections: a first section with a first arc, a second section with a second arc, and a connecting section coupling them. This segmentation allows each section to perform its specific function - the first arc section reduces residual liquid while the second arc section shapes the droplet, and the connecting section ensures smooth transition without causing split ejection.
Solution Approach 2:
Different sections of the nozzle are given different geometric properties tailored to their specific functions. The first arc has specific curvature characteristics optimized for reducing residual liquid, while the second arc has different curvature characteristics optimized for droplet formation. The connecting section has gradually changing curvature to ensure smooth liquid flow transition.
2Volume of moving object
If arcs are positioned close to each other, then nozzle structure is compact, but liquid droplets may be attached to medium in split state
Solution Approach 1:
The nozzle design extends into the third dimension by creating a multi-section internal shape with varying cross-sections along the ejection direction. The first arc and second arc are positioned at different locations along the ejection path, and the connecting section creates a three-dimensional transition path that maintains compact overall volume while ensuring proper droplet formation geometry.
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
This design effectively reduces the possibility of liquid droplets landing on a medium in a split state, suppressing split ejection and curving of droplet trajectories, while preventing air bubble entrainment.
Implementation Method 1
reducing the likelihood of split droplet ejection by utilizing capillary forces to unite the droplets
Data Source
AI summary
A liquid ejecting head includes a nozzle. A sectional shape at a first-position in the nozzle in an ejection-direction is a first-external-shape, and a straight line extending in a second-direction orthogonal to both the ejection-direction and a first-direction being a longitudinal-direction of the first-external-shape and passing through a center of the first-external-shape in the first-direction is a first-center-line. A first-width corresponding to a maximum width in the second-direction in a portion of the first-external-shape on one side in the first-direction with respect to the first-center-line is at a third-position in the first-direction. A second-width corresponding to a maximum width in the second-direction in a portion of the first-external-shape on the other side in the first-direction with respect to the first-center-line is at a fourth-position in the first-direction. A distance between the third-position and the fourth-position is greater than the first-width and the second-width.