Density Unevenness Correction in Image Forming Apparatus

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Solution Overview

Problem

Conventional image forming apparatuses face challenges in correcting density unevenness in the sub-scanning direction, particularly in the post-stop state where the developer conveyance amount is large and unstable, leading to excessive correction amounts and inadequate density correction.

Innovation Solution

An image forming apparatus with a control system that calculates and adjusts correction amounts based on different developer conveyance states, using expressions to determine the necessary correction amounts for each state, ensuring accurate density correction across varying developer conveyance levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If density correction is performed using a fixed correction amount calculated in the post-stop state, then density unevenness can be corrected initially, but the correction amount becomes excessive as the developer conveyance amount decreases, leading to inadequate correction and degraded image quality

Engineering Contradiction:

Improvedensity correction accuracyVSAvoidimage quality stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies dynamics by making the density correction amount variable rather than fixed. The correction amount is dynamically adjusted based on the detected developer conveyance amount, allowing the system to adapt to changing conditions as the apparatus transitions from post-stop state to steady state. This ensures accurate correction throughout the operational lifecycle.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by detecting the actual developer conveyance amount during operation and using this information to adjust the correction amount. The system continuously monitors the developer conveyance amount and modifies the correction amount accordingly, creating a closed-loop control system that maintains image quality stability.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If the developer conveyance amount is large in the post-stop state, then density unevenness increases requiring larger correction amounts, but continuing to use these large correction amounts after the apparatus stabilizes causes excessive correction and deteriorates image quality

Engineering Contradiction:

Improvedensity uniformityVSAvoidexcessive correction

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by modifying the correction amount parameter based on the developer conveyance amount. As the developer conveyance amount decreases from the post-stop state to the steady state, the correction amount parameter is automatically reduced accordingly. This prevents excessive correction while maintaining adequate correction when needed.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If density correction is performed regularly during continuous image formation, then image stabilization is maintained, but the correction amount becomes inaccurate when the developer conveyance amount varies significantly from the reference state

Engineering Contradiction:

Improveimage stabilizationVSAvoidcorrection amount accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies preliminary action by detecting the developer conveyance amount before performing density correction. This allows the system to pre-adjust the correction amount based on the current developer conveyance conditions, ensuring accurate correction from the outset rather than using a fixed reference value.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9606489B2Image forming apparatus, image forming system, and density unevenness correction method

Publication Date: 2017.03.28 KONICA MINOLTA INC

AI summary

An image forming apparatus uses a first developer conveyance amount and a first correction amount calculated respectively in a first state, a second developer conveyance amount and a second correction amount calculated respectively in a second state in which the developer conveyance amount is smaller than the developer conveyance amount of the first state, and a third developer conveyance amount detected in a third state in which the developer conveyance amount is smaller than the developer conveyance amount of the first state and is larger than the developer conveyance amount of the second state to calculate a third correction amount for correcting density unevenness of the toner image in the third state, and perform control to correct the density unevenness of the toner image based on the calculated third correction amount.