Inkjet Head Ejection Timing Compensation for Airflow Displacement

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Solution Overview

Problem

Ink droplets ejected from inkjet heads in image forming apparatuses are affected by both feed airflow and self-induced airflow, leading to ink dot displacements and image degradation due to irregular print density.

Innovation Solution

An image forming apparatus with a controller that compensates ejection timings based on ejection density, considering the number of nozzles, number of lines, and head gap adjustment to minimize ink dot displacements caused by both feed and self-induced airflows, ensuring precise compensation for maintaining print density uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If ink droplets are ejected at high speed to counteract feed airflow, then ink dot displacement is reduced, but self-induced airflow becomes stronger causing opposite displacement

Engineering Contradiction:

Improveink dot position accuracyVSAvoidself-induced airflow

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the ejection speed parameter dynamically based on the number of nozzles. When multiple nozzles eject simultaneously, the ejection speed is reduced to prevent excessive self-induced airflow. When fewer nozzles eject, the ejection speed is increased to counteract feed airflow. This parameter adjustment resolves the contradiction by adapting ejection conditions to the specific printing scenario.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces dynamic control of ejection speed based on real-time nozzle activation patterns. The controller adjusts ejection parameters dynamically according to the number of active nozzles, transforming a static ejection system into a dynamic one that adapts to varying printing conditions, thereby resolving the contradiction between counteracting feed airflow and preventing self-induced airflow effects.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If ejection speed is increased to compensate for feed airflow, then downstream displacement is reduced, but image quality deteriorates due to excessive self-induced airflow effects

Engineering Contradiction:

Improveink dot position accuracyVSAvoidimage quality consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements parameter changes in ejection speed based on the number of simultaneously active nozzles. By reducing ejection speed when multiple nozzles operate together, the system prevents excessive self-induced airflow that would cause ink dot displacement and image quality deterioration, while maintaining sufficient speed to counteract feed airflow effects.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If multiple nozzles eject ink droplets simultaneously to increase productivity, then print speed improves, but ink dot displacement increases due to enhanced self-induced airflow

Engineering Contradiction:

Improveprint speedVSAvoidink dot position accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention applies parameter changes by adjusting ejection speed according to the number of active nozzles. When multiple nozzles eject simultaneously for high productivity, the ejection speed is reduced to minimize self-induced airflow effects. This allows the system to maintain high productivity while preventing ink dot displacement caused by collective nozzle operation.

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 effectively cancels the effects of self-induced airflow on ink dot displacements, preventing irregularities in print density and ensuring high-quality images by precisely adjusting ejection timings according to airflow dynamics and print medium conditions.

Implementation Method 1

a volume of the ink chamber is changed (increased/decreased: the ink chamber is inflated and deflated) by a drive signal

Methodology Applied

Scientific EffectPressure change: Pressure Increase

Implementation Method 2

airflow is generated from an upstream to a downstream along the feed path... the ink droplets are drifted downstream along the feed direction by such airflows

Methodology Applied

Scientific EffectAirflow: Convection

Implementation Method 3

ink droplets ejected from nozzles of inkjet heads may induce airflow by themselves... The self-induced airflow flows downward along an ejection direction of the ink droplets

Methodology Applied

Scientific EffectSelf-induced airflow: Convection

Data Source

PatentUS8926046B2Image forming apparatus

Publication Date: 2015.01.06 RISO KAGAKU CORP

AI summary

An image forming apparatus includes at least one inkjet head which is disposed above a feed path of a print medium and on which plural nozzles are aligned along a primary sweeping direction perpendicular to a feed direction of the print medium fed along the feed path. The image forming apparatus forms images by ejecting ink droplets from the nozzles. The image forming apparatus includes a controller that is operable to compensate ejection timings of ink droplets to be ejected from the nozzles onto the print medium based on ejection density of the ink droplets. The image forming apparatus can form good images that are not affected by ink dot displacements caused by feed airflow even when the ink dot displacements are affected by self-induced airflow.