Inkjet Head Refill Q Factor for Satellite Suppression

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Solution Overview

Problem

Droplet ejection heads face issues with satellite droplets affecting image quality and ejection stability due to inaccurate adjustment of the nozzle surface to recording medium distance, especially when the gap is increased.

Innovation Solution

The inkjet head is designed with a specific refill Q factor of 1.17 or greater, considering ink viscosity, density, and surface tension, to stabilize droplet ejection and suppress satellites, allowing for flexible image recording with improved quality even at larger gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the distance between the nozzle surface and the recording medium is increased, then the flexibility of image recording operation is improved, but the image quality decreases due to increased satellite influence

Engineering Contradiction:
Improveflexibility of image recording operationVSAvoidimage quality
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention changes the physical parameter of the liquid channel by controlling the refill Q factor to be within a specific range (0.9-1.5), which optimizes the liquid surface oscillation characteristics. This parameter control enables stable droplet ejection at larger nozzle-to-medium distances while suppressing satellite droplet formation, thus maintaining image quality while improving operational flexibility

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the distance between the nozzle surface and the recording medium is increased, then the adaptability to different recording media is improved, but the satellite droplets have greater influence on image quality

Engineering Contradiction:
Improveadaptability to different recording mediaVSAvoidsatellite droplet influence
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

By controlling the refill Q factor within the optimized range, the liquid surface oscillation is regulated to prevent excessive satellite droplet generation. This allows the system to maintain high adaptability to various recording media (including three-dimensional surfaces) while minimizing the harmful influence of satellite droplets on image quality

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the refill Q factor is increased, then the liquid surface oscillation is suppressed, but the droplet ejection stability may be affected

Engineering Contradiction:
Improveliquid surface oscillation stabilityVSAvoiddroplet ejection stability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The invention identifies an optimized range for the refill Q factor (0.9-1.5) that balances two competing requirements: suppressing excessive liquid surface oscillation while maintaining droplet ejection stability. This parameter optimization ensures that the liquid surface returns to equilibrium quickly enough to prevent satellite formation, yet the oscillation characteristics remain within bounds that guarantee reliable droplet ejection

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

The solution enables stable and flexible image recording with reduced satellite influence, maintaining image quality even at increased distances between the nozzle and recording medium, supporting various recording media including three-dimensional surfaces.

Implementation Method 1

a pressure chamber that stores the liquid and applies a pressure fluctuation

Methodology Applied
Scientific EffectPressure fluctuation: Pressure Gradient

Implementation Method 2

a refill Q factor related to oscillation of a liquid surface in the nozzle

Methodology Applied
Scientific EffectLiquid surface oscillation: Vibration

Implementation Method 3

a nozzle that communicates with the liquid channel and ejects a droplet of the liquid to which the pressure fluctuation has been applied

Methodology Applied
Scientific EffectPressure-driven ejection: Pressure Gradient

Implementation Method 4

a refill Q factor related to oscillation of a liquid surface in the nozzle is 1.17 or greater when a viscosity of the liquid is 5.7 mPa·s, a liquid density is 1,080 kg/m³

Methodology Applied
Scientific EffectSurface tension: Surface Tension

Data Source

PatentEP4674625A1Droplet-discharging head and drive control method
Publication Date: 2026.01.07 KONICA MINOLTA INC
  • EP4674625A1 patent drawingFigure 1A~1B
  • EP4674625A1 patent drawingFigure 2A~2B
  • EP4674625A1 patent drawingFigure 3A~3C

AI summary

Provided is a droplet-discharging head and drive control method whereby image recording operations can be more flexibly implemented while suppressing reductions in image quality. An inkjet head (1), which is a droplet-discharging head, comprises: an individual flow channel (F) through which ink passes and which includes a pressure chamber (P) that stores the ink and applies pressure fluctuations; and a nozzle (N) that communicates with the individual flow channel (F) and discharges droplets of a liquid to which the pressure fluctuations have been applied. The inkjet head (1) has a structure configured such that the refill Q value related to the vibration of the liquid surface at the nozzle (N) is 1.17 or greater in a case in which the viscosity of the liquid is 5.7 mPa·s, the liquid density is 1080 kg/m3, the speed of sound in the liquid is 1521 m/s, and the surface tension is 42 mN/m.