Inkjet Printing Microfluidic Recirculation Nozzle Clogging

Solution Overview

Problem

Inkjet printing systems face challenges in producing crisp prints on plain paper due to smearing issues caused by typical inkjet ink compositions, which can lead to printability problems such as clogging and poor decap performance, especially when using polyurethane and durability-enhancing solvents at higher concentrations.

Innovation Solution

The use of an ink composition with carbon black pigment, water, and polyurethane, along with microfluidic recirculation assistance, which includes a drop generator and a fluid pump to induce recirculation flow, helps improve durability and printability by reducing nozzle clogging and enhancing ink flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If durability-enhancing solvents and polyurethane are used at higher concentrations to improve print durability, then smear resistance is improved, but nozzle clogging and printability deteriorate

Engineering Contradiction:

Improveprint durabilityVSAvoidnozzle clogging

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The system performs preliminary recirculation of ink through the microfluidic channels before actual printing occurs. This preliminary action prevents pigment settling and maintains ink flow readiness, addressing the clogging issue that arises from using high-concentration durable inks without compromising print durability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention employs a microfluidic ejection assembly with integrated fluid pump to create controlled hydraulic recirculation of ink through microchannels. This hydraulic system maintains continuous ink movement and pressure, preventing nozzle clogging while enabling the use of high-concentration durability-enhancing ink formulations.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Strength

If durability-enhancing solvents and polyurethane are used at higher concentrations to improve print durability, then smear resistance is improved, but print reliability deteriorates

Engineering Contradiction:

Improveprint durabilityVSAvoidprint reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The system performs preliminary recirculation of ink through the microfluidic channels before actual printing occurs. This preliminary action prevents pigment settling and maintains ink flow readiness, addressing the clogging issue that arises from using high-concentration durable inks without compromising print durability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention employs a microfluidic ejection assembly with integrated fluid pump to create controlled hydraulic recirculation of ink through microchannels. This hydraulic system maintains continuous ink movement and pressure, preventing nozzle clogging while enabling the use of high-concentration durability-enhancing ink formulations.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Ease of operation

If microfluidic recirculation is implemented to improve ink flow and reduce clogging, then printability is improved, but device complexity increases

Engineering Contradiction:

ImproveprintabilityVSAvoiddevice complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The invention merges the fluid pump, microfluidic recirculation channels, and drop generator into a single integrated microfluidic ejection assembly. This consolidation reduces overall system complexity by combining multiple functions (ink circulation, pressure regulation, and droplet ejection) into one unified component rather than separate systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The microfluidic recirculation channels are nested within the microfluidic ejection assembly, with the drop generator positioned within the same integrated structure. This nested arrangement allows the recirculation system to be embedded within the existing ejection architecture, minimizing additional complexity while maintaining printability improvements.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 solution achieves improved durability and print reliability, with the ink compositions demonstrating near laser-like or laser-like durability in smear tests and extended decap performance, overcoming the limitations of traditional inkjet inks.

Implementation Method 1

a fluid pump for internally inducing microfluidic recirculation flow of the ink composition into the drop generator

Methodology Applied

Scientific EffectMicrofluidic recirculation:

Implementation Method 2

a drop generator for externally ejecting the ink composition

Methodology Applied

Scientific EffectExternal ejection:

Data Source

PatentUS11066566B2Inkjet printing systems

Publication Date: 2021.07.20 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

The present disclosure is drawn to an inkjet printing system including an ink composition and a microfluidic ejection assembly. The ink composition can include carbon black pigment, from 50 wt % to 80 wt % water, from 10 wt % to 40 wt % of an organic solvent system, and from 0.5 wt % to 6 wt % polyurethane. The microfluidic ejection assembly can include a drop generator for externally ejecting the ink composition, and a fluid pump for internally inducing microfluidic recirculation flow of the ink composition into the drop generator.