Inkjet Correction Chart Layout Reduces Flare

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Solution Overview

Problem

Inkjet image forming apparatuses face challenges in accurately correcting density unevenness due to the phenomenon of flare, which occurs when reading density patterns, leading to erroneous readings and reduced detection accuracy.

Innovation Solution

An image forming apparatus that generates a correction chart with patches representing different densities and marks positioned outside these patches, allowing for the derivation of correction data that minimizes the influence of flare by focusing on the area inside the marks, thereby enhancing detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a correction chart with density patterns is printed and read to correct density unevenness, then correction accuracy is improved, but flare occurs at density boundaries causing erroneous readings and reducing detection accuracy

Engineering Contradiction:
Improvedetection accuracyVSAvoidflare
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The correction chart is segmented into multiple patches with different densities arranged in a gradient sequence. By dividing the correction chart into discrete density zones separated by transition regions, the patent reduces the impact of flare at any single boundary while maintaining overall correction accuracy through averaging across multiple measurements.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the correction chart are designed with different local properties - central patches use higher density values while peripheral patches use lower density values. This local quality variation allows the system to optimize for flare reduction in specific regions while maintaining correction effectiveness across the entire chart.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If density patterns with high contrast are used to improve detection sensitivity, then detection precision is improved, but flare at boundaries increases causing erroneous readings

Engineering Contradiction:
Improvedetection precisionVSAvoidflare
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The correction chart employs a dynamic density gradient where patch densities vary continuously from center to periphery rather than using uniform high-contrast patterns. This dynamic arrangement reduces flare by avoiding abrupt density transitions while maintaining sufficient contrast for accurate detection through the gradient structure.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent converts the harmful effect of flare at density boundaries into a beneficial measurement strategy by deliberately including transition regions in the correction chart. The flare-affected boundary regions provide information about the magnitude and distribution of flare effects, which can be used to correct measurements and improve overall accuracy.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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 reduces the impact of flare, improving the accuracy of density correction and enhancing the overall detection precision of the image forming apparatus.

Implementation Method 1

a phenomenon called a flare may occur at a boundary of a density pattern having different densities, or at a boundary between the different densities, due to scattering or reflection of incident light

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 2

a phenomenon called a flare may occur at a boundary of a density pattern having different densities, or at a boundary between the different densities, due to scattering or reflection of incident light

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP3940593B1Image forming apparatus, method for deriving correction data, and computer-readable carrier medium
Publication Date: 2024.01.10 RICOH CO LTD
  • EP3940593B1 patent drawingFigure 1
  • EP3940593B1 patent drawingFigure 2
  • EP3940593B1 patent drawingFigure 3

AI summary

An image forming apparatus (1) includes an image forming device (12), a reading device (133), a generation unit (311), and a derivation unit (313). The image forming device (12) discharges ink droplets to form an image on a recording medium conveyed in a first direction. The reading device (133) reads the image formed. The generation unit (311) generates a correction chart that includes patches, located in the first direction and representing different densities from each other, and two marks located at different positions from each other in a second direction perpendicular to the first direction. The generation unit (311) locates opposed end portions of the patches in the second direction outside the two marks in the second direction. The derivation unit (313) derives correction data, based on read data provided by the reading device (133) reading an area of the patches existing inside the two marks in the second direction.