Halftone Edge Categorization for Inkjet Print Direction

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Solution Overview

Problem

Inkjet printers face issues with blurred and less clearly defined image edges due to satellite droplets landing outside the image area, especially when printing in both forward and reverse scanning directions, causing trailing edges to be visible and less distinct.

Innovation Solution

A method that identifies and categorizes vertical edges in a halftone image based on lightness differences between areas to the left and right sides of the edges, prioritizing the printing direction to ensure satellite droplets land on similar colors, reducing visibility by making edges leading rather than trailing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If printing is performed in both forward and reverse scanning directions, then productivity is improved, but manufacturing precision deteriorates due to blurred edges

Engineering Contradiction:
Improveprinting speedVSAvoidedge sharpness
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies local quality by differentiating edge treatment based on position and orientation. Vertical edges are identified and categorized as left or right edges, with different printing direction assignments for each. This localized differentiation ensures that satellite droplets always land on the image side of vertical edges regardless of scanning direction, maintaining edge sharpness while enabling bidirectional printing for improved productivity.

Inventive Principle:
Principle #3Local quality

2Ease of operation

If satellite droplets are allowed to land outside the image area, then ease of operation is improved, but object-affected harmful factors increase due to visible satellite droplets

Engineering Contradiction:
Improveprinting operationVSAvoidsatellite droplet visibility
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by identifying and separately treating vertical edges versus other image regions. For vertical edges, the printing direction is specifically controlled to ensure satellite droplets land on the image side. For non-vertical regions, conventional bidirectional printing is maintained. This localized approach eliminates visible satellite droplets at critical edge areas while preserving printing efficiency elsewhere.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3172055B1Categorization of vertical edges corresponding to a halftone image
Publication Date: 2020.07.08 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3172055B1 patent drawingFigure 1
  • EP3172055B1 patent drawingFigure 2
  • EP3172055B1 patent drawingFigure 3~4C

AI summary

A method of printing includes identifying vertical edges in a halftone image. The method also includes determining whether a lightness of color of a first predetermined area to a left side of a respective vertical edge is substantially equal to, less than, or greater than the lightness of color of a second predetermined area to a right side of the respective vertical edge. The method also includes categorizing respective vertical edges left vertical edges, right vertical edges, and neutral vertical edges to prioritize a print direction thereof.