Image Forming Apparatus Registration Correction for Density Stability

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Solution Overview

Problem

Electrical registration error correction in tandem color image forming apparatuses can cause uneven density in high-density images, leading to unstable image density control and color balance fluctuations, especially when using toner images for detection.

Innovation Solution

An image forming apparatus with an image forming position correction unit that adjusts pixel coordinates in the sub-scanning direction and an image forming condition correction unit that discriminates between normal image formation and toner image formation for detection, inhibiting image position correction during toner image formation to prevent density fluctuations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If image forming position correction is applied to correct inclination or curve of scanning lines, then registration error is reduced, but uneven density occurs in high-density images

Engineering Contradiction:

Improveregistration accuracyVSAvoidimage density uniformity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies different processing strategies to different types of images: registration correction is applied to normal images requiring position accuracy, while detection images used for density control are excluded from correction to maintain density uniformity. This local differentiation resolves the contradiction by optimizing each image type for its specific purpose.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the image processing flow into two distinct paths: one for normal image formation with registration correction, and another for detection image formation without correction. This segmentation allows the system to achieve both registration accuracy and density uniformity by treating different image types differently.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If image forming position correction is applied, then color registration is improved, but image density control stability deteriorates

Engineering Contradiction:

Improvecolor registration accuracyVSAvoidimage density control stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent applies registration correction selectively based on image type: normal images receive correction for color registration accuracy, while detection images used for density control are processed without correction to maintain stability. This selective application resolves the contradiction between registration accuracy and density control stability.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If pixel-by-pixel correction is applied, then registration precision is improved, but unnatural steps appear at offset boundaries

Engineering Contradiction:

Improveregistration precisionVSAvoidimage smoothness

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent applies correction only in the main scanning direction rather than correcting both main scanning and sub-scanning directions fully. This partial correction approach achieves sufficient registration precision while avoiding the unnatural steps that would result from complete pixel-by-pixel correction in all directions.

Inventive Principle:

Principle #16Partial or excessive action

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

Stabilizes image density control and prevents density fluctuations in printed images by selectively applying image forming position corrections, ensuring consistent image quality and color balance.

Implementation Method 1

cause an optical sensor to detect an amount of light reflected by the toner image for detection

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS8111415B2Image forming apparatus and method of controlling the same to correct image forming position in an amount smaller than one pixel

Publication Date: 2012.02.07 CANON KK

AI summary

An image forming apparatus of this invention includes an image forming position correction unit which corrects an inclination or curve of an image in the main scanning direction by converting coordinates designating pixel positions of a bitmap image in the sub-scanning direction. It is discriminated whether image formation is normal image formation or formation of the toner image for detection by an image forming condition correction unit. Based on the discrimination result, the image forming apparatus is controlled so as to correct the image forming position by using the image forming position correction unit in a case in which the image formation is discriminated as the normal image formation, but so as not to correct the image forming position by using the image forming position correction unit in a case in which the image formation is discriminated as formation of the toner image for detection.