UV Inkjet Printer Heating Unit for Color Tone Stabilization

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Solution Overview

Problem

When printing with UV curable ink, the color tone of the image immediately after printing deviates from the target color tone, requiring a waiting period for the color tone to settle before correction or proofreading.

Innovation Solution

An inkjet printing apparatus that includes a UV curable ink, an ink-jet head for ejecting the ink, an ultraviolet ray irradiation unit for curing the ink, and a heating unit that stabilizes the color fixation of the UV curable ink by heating it after ultraviolet ray irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If UV curable ink is printed and cured with ultraviolet rays, then the ink is solidified quickly, but the color tone deviates from the target color tone and requires waiting time to settle

Engineering Contradiction:
Improvecuring speedVSAvoidcolor tone settling time
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent applies thermal energy (heat) to change the physical-chemical parameters of the UV curable ink after ultraviolet curing. By heating the ink to a specific temperature range (50-150°C), the color tone stabilization process is accelerated from hours to minutes, resolving the contradiction between quick curing and color tone settling time

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a heating unit as an intermediary component between the ultraviolet irradiation unit and the final printed product. This heating unit acts as a mediator that facilitates the color tone stabilization process by providing thermal energy, enabling faster settling without affecting the initial curing speed

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If excessive initiator is added to ensure curing, then the ink cures completely after UV irradiation, but initiator radicals remain that may affect color stability

Engineering Contradiction:
Improvecuring completenessVSAvoidinitiator radical interference
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful effect of residual initiator radicals into a beneficial process. By applying heat after UV curing, the residual initiator radicals are activated to complete the polymerization reaction, ensuring full curing and color stability. The heating step transforms the potential harm of excess initiator into a benefit of complete ink solidification

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

Solution Approach 2:

The patent extends the curing action continuously from ultraviolet irradiation to thermal processing. The excessive initiator that remains after UV irradiation continues to drive the polymerization reaction when heated, ensuring complete and continuous curing action that stabilizes the color tone without interruption

Inventive Principle:
Principle #20Continuity of useful action

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 heating unit allows the color tone of the printed image to settle to the target color tone in a significantly shorter time compared to without heating, enabling early proofreading and correction of printed matters.

Implementation Method 1

the initiator being cleaved by the ultraviolet ray radiation to generate the initiator radicals that react with the UV curable resin monomers causing the monomers to bond to each other sequentially and be polymerized

Methodology Applied
Scientific EffectPhotopolymerisation: Photopolymerisation

Implementation Method 2

the heating unit is adapted to heat to the extent that initiator radicals are decomposed or volatilized

Methodology Applied
Scientific EffectThermal decomposition: Decomposition (biological)

Implementation Method 3

the heating unit is adapted to heat to the extent that initiator radicals are decomposed or volatilized

Methodology Applied
Scientific EffectVolatilization: Evaporation

Data Source

PatentEP4052907B1Inkjet printing device
Publication Date: 2025.06.04 MIMAKI ENGINEERING CO LTD
  • EP4052907B1 patent drawingFigure 1
  • EP4052907B1 patent drawingFigure 2(a)~2(b)
  • EP4052907B1 patent drawingFigure 3~4

AI summary

An inkjet printing apparatus 1 includes an ink-jet head 23 that ejects UV curable ink to a medium M, an irradiation lamp 25 that irradiates the UV curable ink ejected to the medium M with ultraviolet rays, and a heater 37 that heats the UV curable ink after the ultraviolet ray irradiation by the irradiation lamp 25 and thereby stabilizes color fixation of the UV curable ink. The UV curable ink after the ultraviolet ray irradiation is heated at least at 35°C.