Segmented Charging Brush for Uniform Drum Charging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing image forming apparatuses face challenges in achieving uniform charging of a photosensitive drum while preventing charging defects caused by foreign matter, such as paper dust, which can lead to image defects.

Innovation Solution

The image forming apparatus incorporates a charging brush with a combination of crimped and non-crimped brush fibers. The crimped fibers are concentrated in the upstream portion of the charging brush to entangle foreign matter, while the non-crimped fibers in the downstream portion ensure uniform contact with the photosensitive drum, thereby improving charging uniformity and suppressing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If crimped brush fiber is used to entangle foreign matter, then foreign matter suppression is improved, but charging uniformity deteriorates

Engineering Contradiction:

Improveforeign matter suppressionVSAvoidcharging uniformity

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The charging brush is divided into multiple sections along the moving direction, with each section containing different ratios of crimped to non-crimped fibers. The upstream section has higher crimped fiber ratio for foreign matter entanglement, while downstream sections have lower ratios for uniform charging contact.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the charging brush are assigned different fiber compositions tailored to their specific functions. The upstream portion uses more crimped fibers for foreign matter capture, while downstream portions use more non-crimped fibers for consistent charging contact with the photosensitive drum.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If non-crimped brush fiber is used for uniform contact, then charging uniformity is improved, but foreign matter suppression deteriorates

Engineering Contradiction:

Improvecharging uniformityVSAvoidforeign matter suppression

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The charging brush is segmented into upstream and downstream sections with different fiber compositions. Non-crimped fibers are concentrated in downstream sections where uniform charging contact is prioritized, while upstream sections use more crimped fibers for foreign matter entanglement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The brush structure implements local quality differentiation by placing non-crimped fibers primarily in downstream portions for uniform charging, while crimped fibers are concentrated in upstream portions for foreign matter suppression, allowing each region to optimize its specific function.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If crimped brush fiber ratio is increased, then foreign matter entanglement is improved, but contact pressure uniformity deteriorates

Engineering Contradiction:

Improveforeign matter entanglementVSAvoidcontact pressure uniformity

Core Design Contradiction:

Object-affected harmful factorsVSStress or pressure

Solution Approach 1:

The charging brush is segmented into upstream sections with high crimped fiber ratios for foreign matter entanglement and downstream sections with low crimped fiber ratios for uniform contact pressure, allowing each segment to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

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 enhances the uniformity of charging and effectively suppresses charging defects caused by foreign matter, resulting in improved image quality and reduced occurrence of image defects.

Implementation Method 1

a first type of fiber which is crimped and a second type of fiber which is non-crimped

Methodology Applied

Scientific EffectMechanical interlocking:

Implementation Method 2

a charging brush configured to form a charging portion by being in contact with a surface of the photosensitive member and to charge the surface of the photosensitive member

Methodology Applied

Scientific EffectContact electrification: Triboelectric Effect

Data Source

PatentUS20250130515A1Image forming apparatus

Publication Date: 2025.04.24 CANON KK

AI summary

An image forming apparatus includes a rotatable photosensitive member and a charging brush. The charging brush forms a charging portion in contact with a surface of the photosensitive member and charges the surface of the photosensitive member. The charging brush is provided with brush fiber including a first type of fiber which is crimped and a second type of fiber which is non-crimped. A ratio of the first type of fiber in the brush fiber in a first portion of the charging brush in a moving direction of the surface of the photosensitive member in the charging portion is higher than the ratio of the first type of fiber in the brush fiber in a second portion of the charging brush positioned further downstream than the first portion in the moving direction.