Fluid Ejection Device Nozzle Clogging Prevention

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Solution Overview

Problem

Fluid ejection devices, such as inkjet printheads, face performance degradation due to increased viscosity and solid precipitates from non-volatile components left in nozzles after evaporation of volatile components, leading to clogging and reduced throughput.

Innovation Solution

Incorporating a fluid reservoir on the external surface of the orifice layer near the nozzle, which collects and recirculates fluid, reducing evaporation rates and prolonging the time before viscosity increases, combined with a barrier portion to prevent fluid drainage back into the nozzle, and texturing to enhance wetting characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If fluid remains in the nozzle between ejections, then the nozzle refills by capillary action, but volatile components evaporate and non-volatile components accumulate increasing viscosity

Engineering Contradiction:

Improvetime between drop ejectionsVSAvoidnozzle performance

Core Design Contradiction:

Duration of action of moving objectVSReliability

Solution Approach 1:

The patent extracts the fluid from the nozzle tip by applying a negative pressure pulse that pulls the fluid back into the chamber, removing the fluid that would otherwise remain in the nozzle and undergo harmful evaporation and component accumulation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements periodic reverse pressure pulses at controlled intervals to clear accumulated fluid from the nozzle, preventing viscosity increase and maintaining reliable ejection performance over extended operation periods

Inventive Principle:

Principle #19Periodic action

2Reliability

If service station is used to clear evaporated ink from nozzle, then nozzle performance is maintained, but printer throughput speed is reduced and ink is wasted

Engineering Contradiction:

Improvenozzle performanceVSAvoidprinter throughput speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs preliminary clearing action by applying reverse pressure pulses during normal operation to prevent fluid accumulation and viscosity increase before they reach levels requiring service station intervention, thereby maintaining productivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system performs self-maintenance through automated reverse pressure pulsing that clears the nozzle of accumulated fluid without requiring external service station intervention, eliminating throughput loss and ink waste associated with service station operations

Inventive Principle:

Principle #25Self-service

3Duration of action of moving object

If non-volatile components accumulate in remaining fluid, then viscosity increases and solid precipitates form, but this clogs nozzle and reduces fluid ejection performance

Engineering Contradiction:

Improveoperational timeVSAvoidviscosity increase and precipitate formation

Core Design Contradiction:

Duration of action of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent extracts accumulated fluid containing non-volatile components and precipitates from the nozzle using reverse pressure pulses, removing the harmful substances that would otherwise clog the nozzle and degrade performance

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful effect of fluid accumulation and component accumulation into a beneficial periodic clearing mechanism, where the same fluid that accumulates harmful components becomes the target of controlled reverse pressure pulsing that prevents clogging

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 reduces the frequency of nozzle clearing and maintains performance by slowing down the accumulation of non-volatile components, thereby decreasing the number of 'spits' required to maintain fluid ejection efficiency and preventing clogging.

Implementation Method 1

Firing resistors in a firing chamber located below the orifice plate are selectively energized, thereby heating fluid in the chamber

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

causing some of the fluid in the chamber to boil and form a vapor bubble

Methodology Applied

Scientific EffectBoiling: Boiling

Implementation Method 3

The expanding vapor bubble pushes on the fluid, causing a drop of the fluid to be ejected from the nozzle

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

fluid entering the chamber refills the nozzle by capillary action

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 5

fluid remains in the nozzle and is subject to evaporation or diffusion of volatile components of the fluid out through the nozzle. As the volatile components of the remaining fluid evaporate from the open nozzle surface, non-volatile components are left behind

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 6

evaporation or diffusion of volatile components of the fluid out through the nozzle

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS7524035B2Fluid ejection device

Publication Date: 2009.04.28 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

A fluid ejection device includes an orifice structure with an orifice. A fluid reservoir is on the exterior surface of the orifice structure. A barrier portion is between the fluid reservoir and the orifice.