Recirculation Device Check Valve Printhead Clogging

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Solution Overview

Problem

In printing systems, the precipitation of pigments in print agents, such as metallic particles or titanium oxide in white inks, can lead to clogging of nozzles and reduced operational life of printheads.

Innovation Solution

The implementation of a recirculating print agent system that includes a recirculation device with a check valve, allowing print agent to flow through the recirculation device instead of the printhead when not in use, thereby preventing precipitation and clogging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If print agent is supplied continuously through the printhead, then printing operation is maintained, but pigment precipitation and nozzle clogging occur

Engineering Contradiction:

Improveprinting operationVSAvoidnozzle clogging

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The system dynamically switches between printhead mode and recirculation mode based on operational needs. A valve assembly controlled by a controller directs print agent flow either through the printhead for printing or through the recirculation device for agitation, allowing the system to adapt its flow path dynamically to prevent clogging while maintaining productivity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The recirculation device with agitation mechanism performs preliminary action by continuously agitating print agent in the supply tank before it reaches the printhead. This preliminary agitation prevents pigment precipitation and maintains print agent homogeneity in advance, so that when print agent flows through the printhead, it remains free of precipitated particles that could cause clogging

Inventive Principle:

Principle #10Preliminary action

2Reliability

If print agent is recirculated through agitation, then pigment precipitation is prevented, but system complexity increases

Engineering Contradiction:

Improvepigment precipitation preventionVSAvoidrecirculation system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The recirculation device is integrated into the existing print agent delivery system by combining it with the supply tank and valve assembly that are already part of the printing system. The recirculation device merges with the print agent supply pathway, allowing agitation functionality to be added without requiring completely separate systems, thus limiting the increase in overall complexity

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The valve assembly serves multiple functions: it controls print agent flow to the printhead during printing operations, directs flow to the recirculation device for agitation, and can switch between these modes. This multi-functionality reduces the need for separate dedicated components for each function, thereby limiting system complexity while achieving reliable pigment prevention

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If printhead is used for recirculation, then system simplicity is maintained, but printhead operational life is reduced

Engineering Contradiction:

Improvesystem simplicityVSAvoidprinthead operational life

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The system is segmented into distinct functional components: the printhead is separated from the recirculation function and dedicated solely to printing, while a separate recirculation device handles agitation. This segmentation prevents the printhead from being exposed to harsh recirculation conditions that would reduce its operational life, while maintaining relatively simple system architecture through clear functional separation

Inventive Principle:

Principle #1Segmentation

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 solution effectively reduces the accumulation of precipitated particles in nozzles and extends the operational life of printheads by allowing them to be stored in an external agitation unit, while also enhancing the versatility of the print agent delivery system.

Implementation Method 1

a check valve to allow fluid flow from the second recirculation port to the first recirculation port and to prevent fluid flow from the first recirculation port to the second recirculation port

Methodology Applied

Scientific EffectCheck valve one-way flow: Valve

Implementation Method 2

The recirculation device may comprise a first recirculation port, a second recirculation port in fluid communication with the first recirculation port

Methodology Applied

Scientific EffectFluid agitation preventing precipitation: Stirring

Data Source

PatentUS12304218B2Recirculation devices with check valve

Publication Date: 2025.05.20 HEWLETT PACKARD DEVELOPMENT COMPANY LP

AI summary

Examples relate to a method to recirculate print agent in a printing system. The method comprises detecting a recirculation device comprising a check valve and detecting a printhead connected in parallel to the detected recirculation device. The method further comprises selecting a printhead circulation mode to circulate print agent through the detected printhead and selecting a recirculation device circulation mode to circulate print agent through the detected recirculation device.