Color Registration Correction Using Rotational Variance Factors

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Solution Overview

Problem

Existing image forming apparatuses face challenges in achieving precise color registration due to misalignment caused by roller deformation and eccentricity, which current methods cannot correct for size and variance of toner images across colors.

Innovation Solution

The apparatus employs a sensing unit with LEDs and photo sensors to measure toner image locations on an intermediate transfer belt, using pattern images to calculate rotational variance factors and offsets, allowing for precise color registration by adjusting synchronization signals and video clock frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If timing adjustment is performed to correct maximum delay of photosensitive belts, then color registration is improved, but size of misalignment and variance period cannot be corrected

Engineering Contradiction:
Improvecolor registration precisionVSAvoidcorrection capability for misalignment size and variance
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system dynamically adjusts timing for each color based on measured misalignment characteristics. The control unit varies the timing adjustment amount for each photosensitive belt according to the specific misalignment size and variance period detected, rather than applying a fixed timing correction. This dynamic adaptation allows the system to correct both the magnitude and temporal variations of misalignment across different colors.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes multiple parameters simultaneously including timing adjustment amounts, rotation speeds of photosensitive belts, and positions of transfer belts for each color. By varying these parameters based on measured misalignment characteristics, the system can correct both the size of misalignment and the variance period, achieving comprehensive color registration correction.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If roller deformation and eccentricity are present, then misalignment occurs between toner images, but conventional methods cannot correct the misalignment

Engineering Contradiction:
Improvetoner image alignmentVSAvoidcorrection effectiveness
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The system uses sensing units to detect the actual positions of toner images formed by each color, then feeds this information back to the control unit. Based on the detected misalignment caused by roller deformation and eccentricity, the control unit automatically adjusts timing and operational parameters for each color to compensate for the mechanical imperfections, making the correction effective despite physical wear and deformation.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If photosensitive belts are driven by rollers, then deformation and eccentricity cause misalignment, but no correction method addresses both size and variance

Engineering Contradiction:
Improveautomatic color registrationVSAvoidcolor alignment accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system replaces purely mechanical timing adjustment mechanisms with a control system that uses sensing units and variable parameter adjustment. Instead of relying solely on fixed mechanical corrections, the system electronically controls timing and operational parameters based on real-time measurements, achieving higher precision color alignment while maintaining ease of automatic operation.

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

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 significantly reduces color registration errors from 220µm to 90µm, enabling more precise color alignment and improved image quality.

Implementation Method 1

The apparatus employs a sensing unit with LEDs and photo sensors to measure toner image locations on an intermediate transfer belt

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP2618222B1Image forming apparatus and colour registration method of the same
Publication Date: 2021.05.05 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP2618222B1 patent drawingFigure 1
  • EP2618222B1 patent drawingFigure 2
  • EP2618222B1 patent drawingFigure 3

AI summary

Provided is an image forming apparatus. The apparatus obtains rotational variance factors of an intermediate transfer belt for each of plurality of colors based on locations with respect to second pattern image being obtained by a location calculation unit, corrects the location obtained with respect to a first pattern image based on the rotational variance factor obtained with respect to the color of the first pattern image, obtains an offset of another color with respect to a reference color based on the location after correction, and performs color registration based on the obtained offset to reduce the offset.