Photosensitive Drum Brush Layout for Paper Dust Removal

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Solution Overview

Problem

Existing image forming apparatuses using a direct transfer method face issues with paper dust accumulation on the photosensitive drum, leading to image defects due to insufficient removal of small-sized paper dust and potential toner discharge from the brush member.

Innovation Solution

A brush member is positioned downstream of the transfer portion and upstream of the developing portion, with optimized brush fibers and reduced contact pressure to effectively collect paper dust while minimizing toner discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a brush member contacts the photosensitive drum to collect paper dust, then paper dust removal performance is improved, but toner discharge from the brush member occurs causing image defects

Engineering Contradiction:
Improvepaper dust removal performanceVSAvoidtoner discharge causing image defects
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The brush member is designed with locally differentiated properties: the proximal end has higher brush fiber density for effective paper dust collection, while the distal end has lower density to prevent toner discharge. This local quality variation allows the brush to perform different functions at different locations, resolving the contradiction between dust removal effectiveness and toner discharge prevention.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The brush member is segmented into multiple regions along its length, with each region having different brush fiber densities. This segmentation allows the proximal end to focus on paper dust removal while the distal end focuses on toner discharge prevention, thereby resolving the technical contradiction between these two opposing requirements.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If brush fiber density is increased to improve paper dust collection, then small-sized paper dust removal is enhanced, but brush member accumulates more toner leading to discharge

Engineering Contradiction:
Improvesmall-sized paper dust removalVSAvoidtoner accumulation in brush member
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The brush member implements local quality variation by having higher brush fiber density at the proximal end for effective small-sized paper dust removal, while maintaining lower density at the distal end to minimize toner accumulation and discharge. This spatial differentiation of density resolves the contradiction between dust collection effectiveness and toner accumulation prevention.

Inventive Principle:
Principle #3Local quality

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

The brush member efficiently collects paper dust, reducing visible image defects and toner discharge, thereby improving image quality and reliability.

Implementation Method 1

a brush provided with a plurality of fibers contacting the image bearing member

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4209842B1Image forming apparatus
Publication Date: 2025.12.03 CANON KK
  • EP4209842B1 patent drawingFigure 1
  • EP4209842B1 patent drawingFigure 2(a)~2(b)
  • EP4209842B1 patent drawingFigure 3(a)~3(b)

AI summary

An image forming apparatus includes a rotatable image bearing member, a developing unit to develop an electrostatic latent image at a developing portion, a transfer unit to transfer a developer image to a recording member at a transfer portion; and a brush provided with a plurality of fibers contacting the image bearing member at downstream of the transfer portion and upstream of the developing portion in a rotational direction of the image bearing member. An average contacting pressure of the brush per one fiber to the image bearing member is smaller than a depositing force of the developer not transferred to the recording member to the image bearing member. As the brush in a state of not in contact with the image bearing member is viewed from a free end side of the fibers, an average number of the fibers included in a circumference of a diameter of 100µm is more than one.