Image Density Control in Electrophotographic Apparatus
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Solution Overview
Problem
Electrophotographic image forming apparatuses face the issue of uneven image density due to 'development memory,' where the influence of solid image parts on the developing roller causes non-uniform toner layer potential, leading to inconsistent halftone image density.
Innovation Solution
An image forming apparatus that estimates density lowering positions based on image data and adjusts light exposure amounts to compensate for image density variations, increasing exposure at positions where density is decreased to match predetermined levels, thereby preventing development memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-component developer is used for developing electrostatic latent images, then image formation efficiency is improved, but development memory occurs causing non-uniform image density
Solution Approach 1:
The patent applies preliminary action by rotating the developing sleeve at a predetermined speed before image formation to uniformly distribute the toner layer on the sleeve surface. This preliminary toner distribution prevents development memory effects during subsequent image formation, ensuring uniform image density while maintaining efficient two-component developer operation.
2Speed
If the developing sleeve retains toner from previous solid image parts, then development speed is maintained, but toner layer potential becomes non-uniform causing density variations
Solution Approach 1:
The patent implements periodic action by continuously rotating the developing sleeve at a predetermined speed during the development process. This periodic rotation ensures that toner is uniformly redistributed across the sleeve surface, maintaining consistent toner layer potential and preventing density variations caused by retained toner from previous solid image parts.
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 effectively stabilizes image density across the image, reducing unevenness caused by development memory and ensuring consistent output, even with varying toner charge amounts.
Implementation Method 1
a light exposure section configured to expose an image bearing member to light to form an electrostatic latent image
Implementation Method 2
the toner is frictionally charged and then absorbed by the electrostatic force of the electrostatic latent image
Implementation Method 3
the toner is frictionally charged and then absorbed by the electrostatic force of the electrostatic latent image
Data Source
AI summary
An image forming apparatus includes: an image forming section including a light exposure section configured to expose an image bearing member to light to form an electrostatic latent image, the image forming section being configured to form a toner image on the image bearing member, and to form an image on a recording sheet by transferring the toner image onto the recording sheet; an estimation section configured to estimate a density lowering position on the basis of image data of an image formed by the image forming section, the density lowering position being a position where decrease in image density relative to a predetermined image density is caused in the image; and a control section configured to increase a light exposure amount at the density lowering position estimated by the estimation section on the image bearing member to an amount greater than a predetermined light exposure amount.