Liquid Ejection Apparatus Ink Circulation System

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Solution Overview

Problem

Existing liquid ejection apparatuses face issues with ink ejection failure and image unevenness due to the heating of the ejection object medium, which causes volatilization of water and thickening of ink, leading to changes in coloring material concentration near the ejection orifice.

Innovation Solution

A liquid ejection apparatus with a circulating ink system that flows ink through a pressure chamber between the ejection orifice and the energy-generating element, allowing for the supplementation of fresh ink and prevention of ink thickening, even under high temperature conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the transfer body is heated to improve image transfer properties, then the transfer efficiency is improved, but the ink volatilizes and thickens causing ejection failure

Engineering Contradiction:
Improveimage transfer efficiencyVSAvoidejection reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by circulating fresh ink through the pressure chamber before ejection to preemptively counteract the thickening effect caused by heat. The ink circulation system ensures that new ink continuously replaces old ink in the pressure chamber, maintaining proper viscosity and preventing ejection failure even during heated transfer operations.

Inventive Principle:
Principle #10Preliminary action

2Productivity

If the transfer body is heated to improve image transfer properties, then the transfer efficiency is improved, but the ink concentration changes causing image unevenness

Engineering Contradiction:
Improveimage transfer efficiencyVSAvoidimage density uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The circulation system performs preliminary action by continuously supplying fresh ink to the pressure chamber before concentration changes can occur. This proactive approach ensures that the ink concentration remains uniform and consistent, preventing image density variations and maintaining manufacturing precision during high-temperature transfer processes.

Inventive Principle:
Principle #10Preliminary 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

Prevents ejection failures and image unevenness by maintaining consistent ink flow and concentration, ensuring reliable and high-quality image transfer onto the recording medium.

Implementation Method 1

a liquid supply unit that supplies liquid to a pressure chamber in which energy-generating elements are respectively disposed, in a state where a part of liquid in the pressure chamber is circulated

Methodology Applied
Scientific EffectCirculation flow: Convection

Implementation Method 2

the rate of the melting of a resin by heating during transfer can be improved by heating a transfer part (in which an image is to be transferred from an intermediate transfer body onto a recording medium) to a temperature higher than the minimum film-forming temperature (MFT) of a resin emulsion in an ink

Methodology Applied
Scientific EffectThermal heating: Heating

Implementation Method 3

a liquid ejection head having a plurality of ejection orifices that eject liquid and a plurality of energy-generating elements that generate energy for ejecting the liquid through the ejection orifices

Methodology Applied
Scientific EffectEnergy generation:

Data Source

PatentEP3424715B1Liquid ejection apparatus
Publication Date: 2020.06.24 CANON KK
  • EP3424715B1 patent drawingFigure 1
  • EP3424715B1 patent drawingFigure 2
  • EP3424715B1 patent drawingFigure 3

AI summary

A liquid ejection apparatus includes a liquid ejection head which is provided with a pressure chamber having, in the inside thereof, an energy-generating element, a transfer body onto which a liquid is ejected through the liquid ejection head to form an image, and a pressing unit which presses a recording medium against the transfer body to transfer the image formed on the transfer body onto the recording medium, wherein the liquid ejection apparatus further includes a heating unit for heating the transfer body during a period from the ejection of the liquid through the liquid ejection head and until the pressing of the recording medium by means of the pressing unit, and the liquid in the pressure chamber in the liquid ejection head is circulated between the pressure chamber and the outside of the pressure chamber.