Brush Positioning and Electrostatic Charging for Image Defect Prevention
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Solution Overview
Problem
In image forming apparatuses using a cleaner-less method, the accumulation of paper dust on a brush can lead to image defects such as dotted black spots due to the formation of clumps that inhibit the charging of the photosensitive drum.
Innovation Solution
The brush is positioned such that its contact region with the photosensitive drum overlaps a virtual line containing the drum's rotation axis, and a pre-exposing unit applies a voltage to ensure that the surface potential of the brush contact portion is lower than the drum's surface potential, preventing the accumulation of paper dust clumps and toner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a brush is brought into contact with the photosensitive drum to collect paper dust, then paper dust removal is improved, but fine paper dust accumulates on the brush to form clumps causing image defects
Solution Approach 1:
The patent replaces the mechanical brush contact system with an electrostatic field-based system. A charging member applies electrostatic force to attract and remove paper dust from the photosensitive drum surface without physical contact, preventing dust accumulation that would occur with mechanical brushing.
Solution Approach 2:
The patent introduces a charging member as an intermediary between the paper dust removal function and the photosensitive drum. This charging member creates an electrostatic field that mediates the removal process, allowing dust collection without the brush directly contacting the drum surface.
2Productivity
If the brush contact region is positioned to effectively remove paper dust, then dust collection efficiency is improved, but dust clumps form and pass through to inhibit charging causing black spots
Solution Approach 1:
The patent replaces mechanical brushing with electrostatic charging to eliminate the dust clumping problem. The charging member generates an electrostatic field that removes dust particles individually without the mechanical compression and aggregation that occurs in brush contact systems.
Solution Approach 2:
The patent changes the fundamental parameter of dust removal from mechanical force to electrostatic force. This parameter change transforms the removal mechanism from one that compresses and clumps dust to one that attracts and removes dust particles dispersedly.
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 configuration effectively suppresses the formation of image defects by preventing paper dust and toner accumulation, resulting in improved image quality with reduced black spots.
Implementation Method 1
a charging member configured to face a surface of the image bearing member to form a charging portion and charge the surface of the image bearing member
Implementation Method 2
a pre-exposing unit configured to expose the surface of the image bearing member on a side downstream of the brush contact portion and upstream of the charging portion in the rotation direction of the image bearing member, wherein the pre-exposing unit is configured to expose a downstream-side end portion of the brush contact portion in the rotation direction of the image bearing member
Data Source
AI summary
An image forming apparatus including an image bearing member, a charging member, a developing roller, a transfer roller, and a brush configured to be brought into contact with a surface of the image bearing member on a side downstream of a transfer portion and upstream of a charging portion in a rotation direction of the image bearing member and in which, wherein, after the transfer of a developer image onto a transferred member, a developer remaining on the surface of the image bearing member is collected by the developing roller, the brush is disposed such that, in a cross section perpendicular to a rotation axis of the image bearing member, a contact region of the surface of the image bearing member in contact with the brush overlaps a virtual line containing the rotation axis of the image bearing member and extending upward from the rotation axis in a vertical direction.