Image Density Control in Image Forming Apparatus

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Solution Overview

Problem

Existing image forming apparatuses face challenges in achieving uniform image density due to uneven rotation and sensitivity of image bearing members, leading to noticeable periodic density variations within a page, which are difficult to correct accurately without increasing manufacturing costs or operational complexity.

Innovation Solution

An image forming apparatus equipped with an image density detector and a controller that uses timing correction data to adjust the development and charging biases in synchronization with the rotational period of the image bearing member, ensuring uniform image density by forming specific image patterns to obtain and apply density correction data effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If timing correction data is obtained and applied to adjust development and charging biases in synchronization with the rotational period of the image bearing member, then image density uniformity is improved, but device complexity increases due to additional detection and control mechanisms

Engineering Contradiction:

Improveimage density uniformityVSAvoiddetection and control mechanisms

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary detection of the image bearing member's rotational characteristics and pre-calculates timing correction data before actual image formation. This allows the control mechanism to apply pre-computed corrections in synchronization with the rotational period, reducing the need for complex real-time adjustment mechanisms while achieving uniform image density.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The image density detector provides feedback on the actual density variations caused by uneven rotation and sensitivity of the image bearing member. This feedback is used to calculate timing correction data that compensates for periodic density variations, enabling continuous optimization of image uniformity without requiring complex mechanical adjustments.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If density correction data is applied to correct uneven density, then image quality is improved, but operational complexity increases due to additional control steps

Engineering Contradiction:

Improveimage density uniformityVSAvoidoperational complexity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The system automatically performs detection of density variations, calculation of timing correction data, and application of corrections to the development and charging biases. This self-service mechanism eliminates the need for manual intervention or complex operational steps, as the system autonomously optimizes image density uniformity through integrated control.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If the rotational period of the image bearing member is used for synchronization, then periodic density variations are corrected, but measurement precision requirements increase

Engineering Contradiction:

Improvedensity uniformityVSAvoidrotational period detection

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The system leverages the periodic nature of the image bearing member's rotation to synchronize density correction actions. By detecting the rotational period and applying timing correction data at corresponding intervals, the system effectively corrects periodic density variations without requiring extremely high measurement precision, as the periodic pattern provides a natural reference for synchronization.

Inventive Principle:

Principle #19Periodic 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

This solution enables accurate correction of uneven density issues, enhancing image quality by maintaining uniformity across the page while minimizing operational complexity and manufacturing costs.

Implementation Method 1

an image bearing member which bears an image on a surface

Methodology Applied

Scientific EffectElectrostatic adhesion: Electrostatics

Implementation Method 2

a developer bearing member which supplies toner to the image on the image bearing member to develop the image with toner

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS9152896B2Image forming apparatus and image forming method

Publication Date: 2015.10.06 RICOH CO LTD

AI summary

An image forming apparatus includes an image density detector, an image forming device, a rotator, an image density controller, and a timing correction data obtainer. The image density detector detects a toner density of an image formed on an image bearing member. An image forming device forms the image using a density adjustable element that adjusts the density of the image. The rotator forms an image pattern while the density adjustable element is changed, and a density thereof is detected by the image density detector. The image density controller controls the image forming device using a density correction data for the density adjustable element corresponding to a rotational period of the rotator. The timing correction data obtainer obtains timing correction data for correction of driving timing of the image forming device based on a change in the density of the image pattern detected by the image density detector.