Dual Ink Tank Circulation for Density Uniformity

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Solution Overview

Problem

Ink jet printers experience unstable image quality due to liquid precipitation in the accommodation unit over time, leading to density differences that affect the quality of printed images.

Innovation Solution

A liquid ejecting apparatus with a dual liquid accommodation system and dedicated flow channels that facilitate the reciprocal transfer of ink between a sub-ink tank and a spare ink tank, ensuring uniform ink density through agitation, thereby stabilizing image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the liquid is accommodated in a single accommodation unit for a long period, then the device structure is simple, but the liquid density becomes non-uniform due to precipitation

Engineering Contradiction:
Improveaccommodation unit structureVSAvoidliquid density uniformity
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The single accommodation unit is divided into two separate accommodation units (first and second). Each unit can independently accommodate liquid, and they are connected through flow channels. This segmentation allows the liquid to be circulated between units, preventing precipitation-induced density non-uniformity while maintaining manageable device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system introduces dynamic liquid circulation between the two accommodation units through controlled flow channels. Instead of static liquid storage, the liquid is continuously or periodically transferred between units, creating motion that prevents precipitation and maintains density uniformity throughout the liquid.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the liquid is circulated between two accommodation units, then the liquid density uniformity is improved, but the device complexity increases

Engineering Contradiction:
Improveliquid density uniformityVSAvoidflow channel system
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The flow channels are designed to serve multiple functions simultaneously: they connect the two accommodation units, enable liquid circulation, and facilitate density equalization. By merging these functions into a single integrated channel system, the patent reduces overall device complexity despite the presence of two accommodation units.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The flow channel system is designed as a multi-functional component that performs liquid transport, density equalization, and circulation control. This universal design allows the same structure to achieve multiple objectives, reducing the need for additional specialized components and thereby managing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If the liquid remains static in the accommodation unit, then the device operation is simple, but the image quality becomes unstable due to precipitation

Engineering Contradiction:
Improveliquid circulation operationVSAvoidimage quality stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system enables self-service liquid circulation where the liquid automatically flows between the two accommodation units through the connected flow channels. The design allows the liquid to maintain its own circulation and density uniformity without requiring complex external control mechanisms, thus maintaining ease of operation while ensuring reliable image quality.

Inventive Principle:
Principle #25Self-service

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 apparatus ensures uniform ink density by agitating the ink between the sub-ink tank and the spare ink tank, improving the stability and quality of printed images even after prolonged periods of inactivity.

Implementation Method 1

a liquid supply unit that delivers the liquid from the first liquid accommodation unit to the second liquid accommodation unit through a first flow channel and a second flow channel and that returns the liquid from the second liquid accommodation unit to the first liquid accommodation unit through the second flow channel and the first flow channel

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP2756955B1Liquid discharge device and liquid transport method
Publication Date: 2019.01.23 SEIKO EPSON CORP
  • EP2756955B1 patent drawingFigure 1
  • EP2756955B1 patent drawingFigure 2
  • EP2756955B1 patent drawingFigure 3

AI summary

To improve a stability of a printed image quality by making uniform the density of liquid being ejected from a head. A liquid ejecting apparatus is characterized by including a head unit that ejects a liquid onto a medium, a first liquid accommodation unit that accommodates the liquid, a second liquid accommodation unit that is different from the first liquid accommodation unit, a first flow channel that communicates with the first liquid accommodation unit and the head unit, a second flow channel that communicates with the first flow channel and the second liquid accommodation unit, and a liquid supply unit that delivers the liquid from the first liquid accommodation unit to the second liquid accommodation unit through the first flow channel and the second flow channel and that returns the liquid from the second liquid accommodation unit to the first liquid accommodation unit through the second flow channel and the first flow channel.