Inkjet Head Driving Waveform Suppresses Misting

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Solution Overview

Problem

Inkjet heads using draw-draw driving waveforms often experience misting during ink droplet formation, leading to deteriorated printing quality.

Innovation Solution

An inkjet head with a specific driving waveform that includes an ejection pulse portion where the ink pressure chamber expands and then contracts, with a potential difference between the second and third voltages being greater than that between the third and first voltages, effectively preventing misting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a draw-draw driving waveform is used to eject ink droplets, then ink can be ejected from the nozzle, but ink misting occurs during droplet formation which deteriorates printing quality

Engineering Contradiction:
Improveink ejection capabilityVSAvoidprinting quality
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by transitioning from a static, simple voltage waveform to a dynamic, multi-stage voltage waveform that changes over time. The driving waveform includes a first voltage for chamber expansion, a second voltage for controlled contraction, and a third voltage for complete contraction, creating a time-varying pressure profile that dynamically controls ink ejection to prevent misting while maintaining productivity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs periodic action through a cyclic driving waveform that repeatedly applies expansion and contraction phases. The waveform periodically switches between different voltage levels (first, second, and third voltages) to create rhythmic pressure changes in the ink pressure chamber, enabling controlled droplet formation and ejection without misting

Inventive Principle:
Principle #19Periodic 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

The described driving waveform effectively suppresses ink misting during droplet formation, thereby improving printing quality by ensuring clearer and more precise ink droplet ejection.

Implementation Method 1

an actuator that changes the volume of the ink pressure chamber

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The driving waveform includes an ejection pulse portion that changes from a first voltage to a second voltage at which the ink pressure chamber expands and then from the second voltage to a third voltage at which the ink pressure chamber contracts

Methodology Applied
Scientific EffectElectromechanical transduction: Electromechanical Film

Implementation Method 3

drive actuators, causing changes in volumes of ink pressure chambers in order to eject liquid droplets of ink from nozzles connected to the ink pressure chambers

Methodology Applied
Scientific EffectPressure-driven fluid ejection: Pressure Gradient

Data Source

PatentEP4105027B1Inkjet head
Publication Date: 2025.05.14 RISO TECH CORP
  • EP4105027B1 patent drawingFigure 1
  • EP4105027B1 patent drawingFigure 2~3
  • EP4105027B1 patent drawingFigure 4~5

AI summary

According to an embodiment, an inkjet head includes a nozzle that ejects ink, an ink pressure chamber that connects to the nozzle, an actuator that changes a volume of the ink pressure chamber, and an actuator driving circuit that drives the actuator with a driving waveform. The driving waveform includes an ejection pulse portion that changes from a first voltage to a second voltage at which the ink pressure chamber expands and then changes from the second voltage to a third voltage at which the ink pressure chamber contracts so as to eject the ink from the nozzle. The third voltage is between that of the first and second voltages in potential level. The potential difference between the second and third voltages is greater than the potential difference between the third and first voltages.