Inkjet Printhead Passive Venting for Priming Contamination

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Solution Overview

Problem

Priming a printhead with multiple fluids often results in mixed waste fluid being drawn back into the printhead during blow priming, leading to contamination and requiring substantial servicing to clean the nozzles.

Innovation Solution

A method and system utilizing slow-bleed passive vents and a labyrinth screw to control the priming air pressure, preventing waste fluid from being drawn back into the printhead by creating a tortuous path for air flow and allowing controlled decay of priming pressure, thereby facilitating the removal of waste fluid from the nozzle plate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If blow priming is performed by applying air pressure to the printhead pressure regulation system, then fluid is forced out of the nozzles to flush debris and air, but waste fluid is drawn back into the printhead contaminating stored fluid

Engineering Contradiction:

Improvenozzle clearanceVSAvoidfluid contamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A passive vent is introduced as an intermediary component between the pressure regulation system and the external environment. This vent allows controlled pressure equalization during priming operations, preventing waste fluid from being drawn back into the printhead while still enabling effective nozzle clearance through the blow priming process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The passive vent modifies the pressure parameters within the printhead during priming operations. By providing a controlled path for pressure equalization, the vent changes the pressure dynamics to prevent waste fluid ingress while maintaining the effectiveness of the blow priming process for debris removal.

Inventive Principle:

Principle #35Parameter changes

2Loss of time

If rapid pressure equalization is used during blow priming, then priming operation time is reduced, but waste fluid is drawn back into the printhead

Engineering Contradiction:

Improvepriming operation timeVSAvoidwaste fluid ingress

Core Design Contradiction:

Loss of timeVSObject-affected harmful factors

Solution Approach 1:

The passive vent serves as a mediator that enables controlled pressure equalization. It provides a dedicated path for pressure balance during priming, allowing the process to complete efficiently without causing waste fluid to be drawn back into the printhead, thus resolving the time-contamination contradiction.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The passive vent replaces the need for complex active pressure control mechanisms. Instead of using sophisticated electronic pressure regulation, the invention uses a passive mechanical venting system that naturally equalizes pressure during priming operations, preventing waste fluid ingress while maintaining reasonable operation times.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Substantially prevents fluid contamination during priming operations, ensuring that waste fluid is not drawn back into the printhead, reducing the need for post-prime servicing and maintaining the integrity of stored fluid within the printhead.

Implementation Method 1

applying air pressure to the printhead pressure regulation system, thereby forcing fluid out of the nozzles. Dissipating the air pressure allows the pressure regulation system to reduce and return the printhead's internal pressure to normal.

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

utilizing slow-bleed passive vents and a labyrinth screw to control the priming air pressure, preventing waste fluid from being drawn back into the printhead by creating a tortuous path for air flow

Methodology Applied

Scientific EffectTortuous flow path:

Implementation Method 3

utilizing slow-bleed passive vents and a labyrinth screw to control the priming air pressure, preventing waste fluid from being drawn back into the printhead by creating a tortuous path for air flow

Methodology Applied

Scientific EffectLabyrinth flow resistance:

Data Source

PatentUS7455399B2Inkjet printhead primer for a printing device

Publication Date: 2008.11.25 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

An inkjet printhead for a printing device includes a fluid reservoir operatively disposed within the printhead and a pressure regulation system in fluid communication with the fluid reservoir. The inkjet printhead also includes a nozzle plate having at least one nozzle, wherein the nozzle is in fluid communication with the fluid reservoir; as well as a vent port in fluid communication with the pressure regulation system. Further, the inkjet printhead for a printing device includes a passive vent in fluid communication with the vent port. The passive vent is configured to dissipate air pressure accumulated in the pressure regulation system during priming. The passive vent provides a controlled decay time for the priming air pressure.