Inkjet Head Manifold Flow Direction Inversion for Density Uniformity

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Solution Overview

Problem

The existing liquid ejection head systems experience deterioration in image quality due to temperature changes of the liquid, leading to uneven ink viscosity and ejection amounts, resulting in poor image density and quality.

Innovation Solution

A head system with a differential pressure mechanism between supply and discharge tanks, coupled with a unique ink flow direction configuration in the manifolds, ensures that ink flows in opposite directions through adjacent manifolds, stabilizing the ink flow rate and temperature, thereby maintaining consistent ink viscosity and quality across the print head.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If ink flows through manifolds in the same direction, then the liquid supply system is simple, but temperature changes cause uneven ink viscosity and ejection amounts leading to poor image quality

Engineering Contradiction:
Improveimage qualityVSAvoidliquid supply system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The liquid supply system is segmented into multiple manifolds with alternating flow directions. Each manifold handles ink flow independently with opposite directions, allowing temperature compensation between adjacent manifolds while maintaining manageable system complexity through modular organization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Adjacent manifolds are configured with opposite ink flow directions. This inversion causes temperature-induced viscosity changes to affect adjacent nozzles differently, and when ink is ejected simultaneously, the density variations average out to produce uniform image quality.

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

2Manufacturing precision

If ink flow rate varies due to temperature changes, then energy consumption is reduced, but image density becomes uneven and image quality deteriorates

Engineering Contradiction:
Improveimage density uniformityVSAvoidink flow rate consistency
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

By reversing the flow direction in adjacent manifolds, the patent creates a situation where temperature-induced flow rate variations affect adjacent nozzles in opposite phases. Simultaneous ejection causes these variations to average out, achieving uniform image density despite inconsistent ink flow rates.

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

Solution Approach 2:

The patent changes the flow direction parameter in adjacent manifolds from uniform to opposite directions. This parameter change transforms temperature-induced flow rate inconsistencies into compensating variations that average out during simultaneous ejection, maintaining image quality.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If all nozzles eject ink simultaneously with equal pressure, then the ejection mechanism is simple, but temperature changes cause variations in ejection amount and image quality

Engineering Contradiction:
Improveejection amount consistencyVSAvoidliquid temperature stability
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The patent inverts the flow direction in adjacent manifolds to create opposite flow patterns. This causes temperature-induced pressure variations to affect adjacent nozzles differently, and simultaneous ejection averages these variations out, achieving consistent ejection amounts despite temperature instability.

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

Solution Approach 2:

By changing the flow direction parameter in adjacent manifolds, the patent transforms temperature sensitivity from a source of inconsistency into a compensating mechanism. The parameter change enables simultaneous ejection to produce uniform results even when liquid temperature varies.

Inventive Principle:
Principle #35Parameter changes

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 configuration effectively suppresses image quality deterioration by averaging uneven densities between adjacent nozzles, ensuring consistent ink ejection and improved image formation, even with temperature variations.

Implementation Method 1

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

Methodology Applied
Scientific EffectDifferential pressure: Pressure Gradient

Data Source

PatentEP3888922B1Head system, liquid supply system, printing apparatus, and liquid flow method
Publication Date: 2024.08.28 BROTHER KOGYO KK
  • EP3888922B1 patent drawingFigure 1
  • EP3888922B1 patent drawingFigure 2
  • EP3888922B1 patent drawingFigure 3

AI summary

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