Liquid Ejection Head With Variable Channel Height for Ink Uniformity

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Solution Overview

Problem

Existing liquid ejection heads with multiple ejection orifice arrays experience ink concentration at downstream orifices, leading to decreased droplet landing accuracy and printing quality.

Innovation Solution

The liquid ejection head design includes a configuration where the circulation efficiency at downstream ejection orifices is higher than at upstream orifices, achieved by varying the channel height and orifice width or diameter, and employing filters between adjacent orifices to manage ink flow and concentration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If multiple ejection orifice arrays are provided to achieve high ejection orifice density, then ejection orifice density is improved, but ink concentration occurs at downstream ejection orifices leading to decreased printing quality

Engineering Contradiction:

Improveejection orifice densityVSAvoiddroplet landing accuracy

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent applies local quality by making the channel height variable along the flow direction, with the upstream channel height being greater than the downstream channel height. This creates different local flow characteristics in different regions of the channel, allowing efficient ink supply to upstream orifices while preventing excessive ink accumulation at downstream orifices, thus resolving the contradiction between high orifice density and uniform ink distribution for accurate droplet placement

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the channel (height) along the flow direction to control ink circulation. By gradually decreasing the channel height from upstream to downstream, the ink flow velocity and pressure distribution are optimized, ensuring that ink is efficiently circulated and ejected at all orifices without excessive concentration at downstream positions, thereby maintaining high printing quality across all ejection orifices

Inventive Principle:

Principle #35Parameter changes

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 suppresses ink concentration at downstream orifices, maintaining droplet landing accuracy and improving printing quality by ensuring efficient ink circulation and ejection.

Implementation Method 1

a heating element that heats the liquid

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a bubble that is generated by the heating element and that acts on the liquid to be ejected from the ejection orifice

Methodology Applied

Scientific EffectBubble expansion: Bubble

Data Source

PatentUS12454129B2Liquid ejection head

Publication Date: 2025.10.28 CANON KK

AI summary

In a liquid ejection head capable of suppressing a decrease in printing quality, circulation efficiency J at an ejection orifice on a downstream side in a flow direction in a channel is set high.