Image Forming Apparatus Variable Magnification Shrinkage Compensation

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Solution Overview

Problem

Conventional electrophotographic image forming apparatuses face challenges in accurately printing images due to shrinkage of the print medium caused by heat, leading to size discrepancies between printed images and their monitor representations, which increases costs and deteriorates image quality, especially when special color images like transparent or white are involved.

Innovation Solution

The solution involves allowing users to input magnification or reduction ratios for images to be printed, applying these ratios vertically and horizontally, and using a data parser to process print data for variable magnification, enabling precise placement of images over each other to compensate for medium shrinkage, thereby eliminating the need for sensors to measure image dimensions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If sensors are used to measure the size of the print medium and printed images, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a reference pattern printed on the print medium as a copy substitute for physical sensors. The reference pattern contains known dimensional information that allows the system to calculate shrinkage ratios through image processing, eliminating the need for expensive sensor hardware while maintaining measurement capability

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent replaces the mechanical sensor-based measurement system with an optical/image processing-based system. By capturing images of the reference pattern and analyzing pixel dimensions computationally, the system substitutes physical measurement mechanics with digital image analysis, reducing hardware complexity

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the print medium is heated to fix the developer image, then the fixing function is achieved, but the print medium and image shrink, causing size discrepancies

Engineering Contradiction:
Improvefixing functionVSAvoidimage size accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by printing a reference pattern on the print medium before the actual image content. This reference pattern serves as a pre-established measurement standard that allows the system to predict and compensate for shrinkage that will occur during the subsequent heating and fixing process, maintaining image size accuracy despite thermal contraction

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using the reference pattern to measure actual shrinkage dimensions after fixing, then using this measured shrinkage information to calculate correction factors. These feedback-derived correction factors are applied to subsequent printing operations to compensate for thermal shrinkage and maintain manufacturing precision

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If special color images are printed in multiple passes, then image quality is improved, but the complexity of coordinating magnification ratios between passes increases

Engineering Contradiction:
Improveimage qualityVSAvoidprinting process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by using a single reference pattern that serves multiple functions across different printing passes. The same reference pattern is used to measure shrinkage for both the first pass (special color) and second pass (CMYK) printing, providing a unified basis for calculating magnification ratios and maintaining coordination between multiple printing operations

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses parameter changes by dynamically adjusting the magnification ratio based on measured reference pattern dimensions. The system calculates the shrinkage ratio from the reference pattern and applies this as a correction parameter to the printing process, allowing flexible adaptation of printing parameters to maintain image quality across multiple passes

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

This approach ensures that the dimensional ratios of printed images match their monitor representations, enhancing print quality and reducing costs by eliminating the need for sensors, while allowing for precise correction of image positions to maintain image integrity across multiple printing passes.

Implementation Method 1

a developer image is first transferred onto a print medium and is then fixed by heat and pressure

Methodology Applied
Scientific EffectHeat: Heating

Implementation Method 2

a developer image is first transferred onto a print medium and is then fixed by heat and pressure

Methodology Applied
Scientific EffectPressure: Pressure Increase

Implementation Method 3

When heat is applied to the developer image on the print medium, the printed image and the print medium shrink by a certain percentage

Methodology Applied
Scientific EffectThermal shrinkage: Thermal Contraction

Data Source

PatentEP2863267B1Image forming apparatus, print data producing apparatus and image forming system
Publication Date: 2019.11.27 OKI DATA CORP
  • EP2863267B1 patent drawingFigure 1~2
  • EP2863267B1 patent drawingFigure 3~4
  • EP2863267B1 patent drawingFigure 5A~6

AI summary

A first developer image is overprinted on a second developer image printed on a medium. A user inputs, through an inputting section (106, 170), a magnification ratio or a reduction ratio of at least one of the first developer image and the second developer material image that should be printed. The magnification and the reduction ratios are applied vertically and horizontally substantially. A data parser (103, 111) performs parsing of print data. A magnification/reduction section (104, 112, 114) produces the first image and the second image from the print data based on a result of the parsing. The first image is subjected to a variable magnification process. An image forming section (105, 130) transfers and fixes the first developer material image onto the medium after the variable magnification process, and then transfers and fixes the second developer material image on the medium so that the first and second developer material images are placed one over the other.