Photosensitive-Drum Conductive Brush for Toner and Paper Dust Control

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Solution Overview

Problem

Existing image forming apparatuses face issues with toner accumulation in the brush member, leading to toner lumps being discharged onto the photosensitive drum, causing image defects, while also experiencing degraded paper dust collection performance due to paper dust slipping through the brush member, affecting charging and image quality.

Innovation Solution

The image forming apparatus employs a brush member with a specific configuration that balances paper dust collection and toner discharge by using a conductive nylon thread with a controlled inter-fiber average distance and density, ensuring effective removal of paper dust while minimizing toner accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the brush member accumulates a large amount of toner, then the paper dust collection performance is improved, but toner lumps are ejected onto the photosensitive drum causing image defects

Engineering Contradiction:
Improvepaper dust collection performanceVSAvoidtoner lump ejection
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by controlling the inter-fiber average distance of the brush member to be within a specific range (5 μm to 50 μm) and adjusting the brush member density (100 kF/inch² to 300 kF/inch²). These parameter optimizations allow the brush member to effectively collect paper dust while preventing excessive toner accumulation and lump ejection.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by using conductive nylon thread with specific physical properties (diameter of 1 μm to 10 μm) to create a brush member with localized characteristics that balance paper dust collection and toner discharge. The conductive property and controlled fiber diameter enable the brush to perform its dual function effectively.

Inventive Principle:
Principle #3Local quality

2Object-generated harmful factors

If the brush member does not accumulate toner, then toner lump ejection is prevented, but paper dust collection performance is degraded

Engineering Contradiction:
Improvetoner lump ejectionVSAvoidpaper dust collection performance
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent resolves this contradiction by optimizing the inter-fiber average distance parameter to fall within 5 μm to 50 μm. This specific range allows sufficient toner passage to prevent accumulation while maintaining close enough fiber spacing to collect paper dust effectively.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite material principles by combining conductive nylon thread with specific physical properties (diameter, conductivity, elasticity) to create a brush member that simultaneously achieves paper dust collection and toner discharge. The material selection and configuration create a composite structure with balanced functional properties.

Inventive Principle:
Principle #40Composite materials

3Reliability

If the inter-fiber average distance is small, then paper dust collection is improved, but toner discharge is hindered

Engineering Contradiction:
Improvepaper dust collectionVSAvoidtoner discharge
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies parameter changes by setting the inter-fiber average distance within the optimized range of 5 μm to 50 μm. This parameter optimization allows the brush member to collect paper dust effectively while maintaining sufficient spaces for toner particles to pass through and discharge properly.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by using conductive nylon thread with controlled fiber diameter (1 μm to 10 μm) and specific density characteristics. This creates localized regions with appropriate porosity and conductivity that balance paper dust collection and toner discharge functions.

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 solution effectively reduces toner accumulation and maintains high paper dust collection performance, preventing image defects and ensuring consistent image quality by optimizing the brush member's design to manage both toner and paper dust effectively.

Implementation Method 1

a brush member (11) that contacts the photosensitive drum (1) in a rotation direction of the photosensitive drum (1)

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the brush member (11) is made of a conductive material, and an average value of inter-fiber distances in the brush member (11) is 5 μm to 50 μm

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentEP4215993B1Image forming apparatus
Publication Date: 2025.07.23 CANON KK
  • EP4215993B1 patent drawingFigure 1
  • EP4215993B1 patent drawingFigure 2
  • EP4215993B1 patent drawingFigure 3

AI summary

An image forming apparatus (100) includes a rotatable image bearing member (1), a developing member (31) to develop an electrostatic latent image at a developing portion (P2), a transfer member (5) to transfer a developer image to a recording member at a transfer portion (N); and a brush (11) provided with a plurality of base materials (11a) 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. The developer remaining on the surface of the image bearing member is collected in the developing portion. An average distance (I) between base materials of the brush with respect to a rotational axis direction of the image bearing member is larger than an average particle diameter of the developer, and is equal to or less than a length corresponding to a spatial frequency visually recognizable by a user when the image formed by the image forming apparatus is observed by the user.