Filter Device for Recycled Print Head Atmosphere

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Solution Overview

Problem

Continuous inkjet printers face challenges in efficiently recovering solvent vapors and managing solvent consumption due to fast evaporation from the jet curtain, leading to environmental contamination and increased humidity, which affects the printer's operation and efficiency.

Innovation Solution

A device with filters arranged at the outlet of the ink reservoir is used to recycle air drawn in through the printer, separating solvent vapors and particles, and reintroducing a reverse current of solvent to flush out trapped particles, maintaining a closed loop and reducing condensation and aerosol formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a filter is placed in the solvent recovery circuit to separate particles, then filtration efficiency is improved, but the filter becomes clogged with condensed solvent and particles, reducing its lifespan and requiring frequent maintenance

Engineering Contradiction:
Improvefiltration efficiencyVSAvoidfilter lifespan
Core Design Contradiction:
Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The invention applies preliminary action by introducing a reverse flow of solvent vapor and/or liquid through the filter before normal operation, or at the beginning of operation, to pre-clean the filter and prevent initial clogging. This preliminary cleaning action removes particles and condensed solvent that would otherwise accumulate and block the filter pores, thereby extending filter lifespan while maintaining high filtration efficiency throughout operation

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention applies inversion by reversing the normal flow direction through the filter. Instead of allowing solvent and particles to flow through the filter in the normal operation direction, the system periodically introduces a reverse flow that moves solvent vapor and liquid through the filter in the opposite direction, carrying trapped particles away from the filter medium and preventing clogging, thus extending filter life while maintaining filtration efficiency

Inventive Principle:
Principle #13The other way round (Inversion)

2Loss of substance

If the printer operates in a closed loop to recycle air, then solvent consumption is reduced, but humidity accumulates and condensation forms, affecting printer operation

Engineering Contradiction:
Improvesolvent consumptionVSAvoidcondensation and humidity
Core Design Contradiction:
Loss of substanceVSObject-affected harmful factors

Solution Approach 1:

The invention applies extraction by removing condensed solvent and excess humidity from the closed loop system through a dedicated extraction pathway. The system separates the condensation removal function from the main recycling loop, allowing condensed solvent to be extracted and returned to the ink reservoir while maintaining the closed loop for vapor recycling, thus preventing humidity accumulation and condensation-related operational issues while preserving solvent conservation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention applies parameter changes by dynamically adjusting temperature and pressure parameters within the closed loop system to control the phase state of solvent and manage condensation. By varying temperature gradients and pressure differentials, the system optimizes solvent vaporization in the print head while controlling condensation in specific zones, and manages the phase changes of extracted condensate, thereby maintaining efficient operation in a closed loop environment

Inventive Principle:
Principle #35Parameter changes

3Productivity

If solvent is rapidly evaporated from the jet curtain for printing, then printing efficiency is improved, but environmental contamination increases and humidity rises

Engineering Contradiction:
Improveprinting efficiencyVSAvoidenvironmental contamination
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The invention applies the blessing in disguise principle by capturing the solvent vapor that would otherwise be released as environmental contamination and converting it into a beneficial resource. The closed loop system recycles the evaporated solvent vapor back to the ink reservoir, where it condenses and returns to the ink supply, transforming what was previously harmful emissions into a means of conserving solvent and reducing the need for frequent ink refilling, thereby maintaining high printing efficiency while eliminating environmental contamination

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 solution minimizes solvent consumption, reduces environmental contamination, and maintains printer efficiency by effectively recycling air and managing solvent vapors, while extending filter life and maintaining high filtration efficiency.

Implementation Method 1

filtration of an atmosphere output from at least one ink reservoir of the printer making use of at least one filter

Methodology Applied
Scientific EffectPhysical filtration: Filter (physical)

Implementation Method 2

introducing a reverse current of solvent to flush out trapped particles

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 3

separating solvent vapors and particles

Methodology Applied
Scientific EffectCondensation: Condensation

Data Source

PatentEP3284601B1Method and device for filtering the recycled atmosphere of a print head
Publication Date: 2021.11.17 DOVER EUROPE SARL
  • EP3284601B1 patent drawingFigure 1~2
  • EP3284601B1 patent drawingFigure 3~4B
  • EP3284601B1 patent drawingFigure 5A~5C

AI summary

The invention relates to a device for recovery of the atmosphere containing solvent vapours from at least one ink recovery reservoir (10) of a print machine comprising: - n (n≥ 1) filter(s) (20, 20a) arranged at the outlet from at least one ink reservoir (10), each filter: - comprising an inlet face (21), an outlet face (22) and a filter body between these two faces, - comprising means (25) of recovering at least part of a liquid condensed on the surface of the inlet face (21) of the filter, before this liquid has passed through it, - and being : * either upstream from solvent extraction means (26), an atmosphere output from the reservoir (10), passing through the inlet face (21), and then the filter body and the outlet face (22) before being sent to the solvent extraction means (26), * or downstream from solvent extraction means (26), an atmosphere from the solvent extraction means (26) passing through the inlet face (21), and then the filter body and the outlet face (22) before being sent to at least one print head (1) of the print machine, respectively.