Printhead Maintenance Dots to Prevent Visible Print Artefacts

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Solution Overview

Problem

Print quality is compromised due to nozzle evaporation and clogging in printheads, particularly in solvent or water-based printing systems, leading to visible artefacts from spit on page operations.

Innovation Solution

Implement a method to limit spit on page dots to non-printing areas by analyzing print job information to designate printing and non-printing regions, and generating a print output file that overlays spit on page dots in non-printing areas, ensuring they are not visible in the final printed output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spit on page operations are performed to maintain nozzle health, then nozzle reliability is improved, but visible artefacts appear on the printed output

Engineering Contradiction:
Improvenozzle reliabilityVSAvoidvisible artefacts
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful spit dots from the printing areas by designing maintenance operations that occur only in non-printing areas. The printhead performs spit operations in designated maintenance zones that are separate from and not visible in the final printed output, thereby removing the harmful visual effect while preserving the beneficial nozzle maintenance function.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The printing medium surface is segmented into printing areas and non-printing areas. The system performs different operations in different segments: image formation in printing areas and nozzle maintenance in non-printing areas. This spatial segmentation allows simultaneous achievement of print quality and nozzle health maintenance without mutual interference.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If nozzles are left uncapped between printing operations, then ease of operation is improved, but nozzle clogging occurs due to evaporation

Engineering Contradiction:
Improveease of operationVSAvoidnozzle functionality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system performs preliminary spit operations in non-printing areas before actual printing begins. This preliminary action ensures nozzles are clear and ready for printing without requiring manual intervention or visible maintenance operations during the printing process itself, thus maintaining both ease of operation and nozzle functionality.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The printhead performs self-maintenance through automated spit operations in non-printing areas. The system monitors nozzle conditions and automatically executes maintenance routines without external intervention, keeping nozzles functional while requiring minimal user interaction and maintaining operational simplicity.

Inventive Principle:
Principle #25Self-service

3Reliability

If spit on page dots are placed in printing areas, then nozzle maintenance is effective, but print quality deteriorates due to visible dots

Engineering Contradiction:
Improvenozzle performanceVSAvoidprint quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by assigning different functions to different spatial locations on the printing medium. Non-printing areas are designated specifically for maintenance operations where spit dots are acceptable and even desirable for nozzle health. Printing areas maintain high quality standards where no spit dots appear. This localized functional assignment resolves the contradiction between effective maintenance and print quality.

Inventive Principle:
Principle #3Local quality

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

Enhances print quality by preventing nozzle deterioration and minimizing visible spit on page artefacts, particularly in dye sublimation printing, by strategically placing spit on page dots in non-printing regions.

Implementation Method 1

a reduction in print quality may arise due to evaporation from the nozzles between printing liquid ejection

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 2

The printing liquid used may be water or solvent based and may be stored in reservoirs or cartridges in the printer until used for printing an image

Methodology Applied
Scientific EffectStorage:

Data Source

PatentEP3776166B1Method and apparatus for printhead maintenance
Publication Date: 2025.08.13 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3776166B1 patent drawingFigure 1~2
  • EP3776166B1 patent drawingFigure 3
  • EP3776166B1 patent drawingFigure 4

AI summary

In an example, there is provided a method and apparatus for generating a print output file, the method comprising receiving at least one image to be printed, determining a printing area corresponding to a region containing the at least one image to be printed and a non-printing area corresponding to a remaining region, providing a spit-on-page dot pattern limited to the non-printing area, and generating the print output file comprising the dot pattern and the at least one image.