Liquid Ejection Head Dual-End Supply for Pressure Uniformity

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Solution Overview

Problem

The existing liquid ejection heads experience variations in pressure among individual passages, leading to inconsistent ink ejection from nozzles due to differences in supply and return liquid passage configurations.

Innovation Solution

The liquid ejection head incorporates a configuration where supply and return liquid passages are coupled through multiple inlets and outlets, with each individual passage receiving ink from both ends of the supply passages and returning ink to both ends of the return passages, reducing pressure variations by distributing ink flow more evenly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If liquid is supplied from one end of the second common liquid passages, then the structure is simple, but the pressure varies among individual passages leading to inconsistent ejection

Engineering Contradiction:

Improveliquid passage structureVSAvoidejection consistency

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The second common liquid passage is divided into multiple segments with separate inlets (first and second common liquid passage inlets), allowing independent pressure control for different groups of individual passages. This segmentation enables uniform pressure distribution across all nozzles while maintaining structural organization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the liquid passage system are given different characteristics - the first common liquid passage supplies liquid to one end of individual passages while the second common liquid passage supplies to the other end, creating localized pressure balance that ensures consistent ejection across all nozzles.

Inventive Principle:

Principle #3Local quality

2Productivity

If liquid flows through long common liquid passages, then all nozzles can be supplied, but pressure loss increases causing variations in pressure among individual passages

Engineering Contradiction:

Improvenumber of nozzles suppliedVSAvoidpressure uniformity

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The liquid supply system is segmented into two parallel common liquid passages, each serving different ends of the individual passages. This divides the long flow path into shorter segments, reducing cumulative pressure loss while maintaining the ability to supply all nozzles effectively.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system creates equipotential pressure conditions by supplying liquid from both ends of the individual passages through separate common liquid passages, ensuring that pressure is balanced across all nozzles despite the extended coverage area.

Inventive Principle:

Principle #12Equipotentiality

3Manufacturing precision

If multiple common liquid passages are used to reduce pressure variation, then ejection consistency improves, but the device complexity increases

Engineering Contradiction:

Improveejection consistencyVSAvoidliquid passage configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The first and second common liquid passages are merged into a coordinated system where both supply liquid to the same set of individual passages from opposite ends. This combination achieves pressure balance and ejection consistency while maintaining a relatively compact and organized structure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Both the first and second common liquid passages perform the same fundamental function of supplying liquid to individual passages, but from different directions. This multi-functional approach allows a single system to achieve both comprehensive coverage and pressure uniformity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration ensures more uniform pressure application across individual passages, resulting in consistent ink ejection from nozzles and reducing fluid crosstalk and pressure loss, while also simplifying the design and reducing the overall size of the liquid passages.

Implementation Method 1

the pressure applied to each of the individual passages communicating with each of the second common liquid passages (the supply liquid passages) increases with decrease in distance to the one end of the second common liquid passage

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS11155088B2Liquid ejection head

Publication Date: 2021.10.26 BROTHER KOGYO KK

AI summary

A liquid ejection head includes: individual passages each having a nozzle; supply liquid passages each communicating with an individual inlet of a corresponding one of the individual passages; return liquid passages each communicating with an individual outlet of a corresponding one of the individual passages; a first supply coupling liquid passage coupling the supply liquid passages to each other and communicating with a first inlet of each of the supply liquid passages; and a second supply coupling liquid passage coupling the supply liquid passages to each other and communicating with a second inlet of each of the supply liquid passages. In each of the supply liquid passages, the individual inlet of the corresponding one of the individual passages is located between the first inlet and the second inlet.