Dual-Channel Ink Supply Head for Print Quality

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Solution Overview

Problem

Existing liquid ejection heads in image recording apparatuses suffer from image quality deterioration due to temperature changes in the liquid, leading to uneven ink viscosity and ejection amounts.

Innovation Solution

A head system with a dual-channel ink supply and discharge mechanism that generates differential pressures between supply and discharge tanks, ensuring opposite flow directions through adjacent manifolds to offset temperature-induced density variations, thereby stabilizing ink flow and maintaining image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If liquid is supplied through a single channel from supply tank to discharge tank, then the structure is simple, but temperature-induced density variations cause uneven ink flow and image quality deterioration

Engineering Contradiction:
Improvechannel structureVSAvoidimage quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The single liquid supply channel is divided into multiple channels (first liquid supply channel and second liquid supply channel) that transport liquid in opposite directions. This segmentation allows temperature-induced density variations to be distributed and averaged across multiple paths, preventing uneven flow accumulation and maintaining consistent ejection performance throughout the print head.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Adjacent manifolds are configured to receive liquid flows moving in opposite directions. By inverting the flow direction in alternating manifolds, the system creates a balanced temperature distribution where warmer and cooler liquid paths compensate for each other, stabilizing the overall liquid temperature and density across the entire head system.

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

2Productivity

If liquid flow rate is increased to improve productivity, then more ink can be ejected, but temperature changes accelerate causing viscosity variations and ejection instability

Engineering Contradiction:
Improveink ejection rateVSAvoidejection stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The liquid supply system is segmented into multiple parallel channels that collectively handle high flow rates while maintaining stable temperature. Each channel operates at a moderate flow rate, preventing excessive heating or cooling, while the combined output achieves the required productivity. This segmentation decouples the relationship between total flow rate and temperature variation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the flow distribution parameters across multiple channels rather than increasing flow through a single channel. By adjusting the number and configuration of parallel channels, the system achieves high productivity while maintaining flow rates per channel that minimize temperature-induced viscosity changes, ensuring ejection stability.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If differential pressure is increased to improve liquid supply efficiency, then ink delivery is enhanced, but temperature-induced density variations cause flow instability

Engineering Contradiction:
Improveliquid supply efficiencyVSAvoidliquid flow consistency
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The high differential pressure supply is segmented into multiple channels experiencing lower individual pressure drops. This segmentation reduces the temperature effects associated with high-pressure flow while maintaining overall supply efficiency. Each channel operates at moderate pressure, minimizing adiabatic heating and density variations, while the collective system achieves high productivity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Adjacent channels are configured with opposite flow directions, creating a balancing effect where pressure-induced temperature variations in one channel are compensated by opposite variations in adjacent channels. This inversion strategy stabilizes the liquid composition and flow consistency across the entire system while maintaining high supply efficiency.

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

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 system effectively suppresses image quality deterioration by averaging temperature-induced density variations across the print medium, ensuring consistent ink ejection and improved image formation.

Implementation Method 1

a first differential pressure mechanism configured to generate a differential pressure between the first supply tank and the first discharge tank

Methodology Applied
Scientific EffectDifferential pressure: Pressure Gradient

Implementation Method 2

generates opposite flow directions through adjacent manifolds to offset temperature-induced density variations

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3888921B1Head system, liquid supply system, printing apparatus, and liquid flow method
Publication Date: 2024.08.28 BROTHER KOGYO KK
  • EP3888921B1 patent drawingFigure 1
  • EP3888921B1 patent drawingFigure 2
  • EP3888921B1 patent drawingFigure 3

AI summary

There is provided a head system including: a head; a first supply channel which has a first supply port configured to receive a liquid, and which extends between the first supply port and the head; and a first discharge channel which has a first discharge port configured to discharge the liquid and which extends between the first discharge port and the head. The head has two groups each including a manifold which extends in a first direction and a plurality of pressure chambers each connected to the manifold and a nozzle. The two groups include a first group and a second group arranged in an order of the first group and the second group in a second direction intersecting the first direction. One end of the manifold included in each of the two groups is positioned on a first side in the first direction, and an opposite end of the manifold included in each of the two groups is positioned on a second side in the first direction. The first supply channel is connected to the one end of the manifold included in the first group, and is connected to the opposite end of the manifold included the second group. The first discharge channel is connected to the opposite end of the manifold included in the first group and is connected to the one end of the manifold included in the second group.