Shielding Member Prevents Toner Scattering in Image Forming Apparatus

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Solution Overview

Problem

In image forming apparatuses using a contact DC charging system, toner scattering from the cleaning member, such as a brush, causes image defects and contamination of the charging roller, leading to poor charging and potential damage to the developing sleeve due to adhered toner.

Innovation Solution

The image forming apparatus includes a developer bearing member positioned below the cleaning member, with a conductive elastic layer and a shielding member having magnetic properties placed between the cleaning member and the developer bearing member to prevent toner scattering and contamination, ensuring the entire region of the cleaning member is accommodated within the elastic layer and reducing toner adhesion to the developing sleeve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cleaning member (brush) is used to clean the charging member, then charging quality is improved by removing toner contamination, but toner scattering occurs causing image defects and contamination of the developing cartridge

Engineering Contradiction:

Improvecharging qualityVSAvoidtoner scattering

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A shielding member is introduced as an intermediary between the cleaning member and the developing cartridge. This shielding member intercepts and contains scattered toner, preventing it from reaching the developing cartridge while allowing the cleaning operation to continue effectively

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The harmful effect of toner scattering is extracted and isolated from the main system by positioning the shielding member to capture scattered toner in a specific region, separating the cleaning function from the harmful scattering effect

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If the cleaning member contacts the charging member to remove toner, then charging performance is improved, but the cleaning member itself becomes contaminated with toner

Engineering Contradiction:

Improvecharging performanceVSAvoidtoner contamination of cleaning member

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The shielding member acts as an intermediary barrier that captures toner particles before they can extensively contaminate the cleaning member and surrounding areas, facilitating easier maintenance and toner recovery

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If no cleaning device is provided for the photosensitive member, then the apparatus is miniaturized and waste toner is reduced through cleanerless system, but toner accumulates on the charging member causing poor charging

Engineering Contradiction:

Improveapparatus sizeVSAvoidcharging reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The cleaning member automatically cleans the charging member during normal operation without requiring a separate cleaning device for the photosensitive member. The shielding member supports this self-service cleaning by containing scattered toner

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The cleaning member serves multiple functions: it cleans the charging member to maintain charging reliability, and when combined with the shielding member, it also prevents toner scattering that would otherwise contaminate the developing cartridge

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 reduces toner scattering and contamination, preventing image defects and maintaining the integrity of the developing sleeve by ensuring the toner is collected and reused efficiently, thereby improving the charging process and reducing maintenance issues.

Implementation Method 1

a shielding member having magnetic properties placed between the cleaning member and the developer bearing member to prevent toner scattering

Methodology Applied

Scientific EffectMagnetic properties: Magnetism

Implementation Method 2

a developer bearing member... with a conductive elastic layer... ensuring the entire region of the cleaning member is accommodated within the elastic layer

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS10209668B2Image forming apparatus, process cartridge, developing cartridge, and drum cartridge

Publication Date: 2019.02.19 CANON KK

AI summary

An image forming apparatus in which a developer bearing member is disposed below a cleaning member, which cleans a charging member, so as to overlap with the cleaning member when viewed in a vertical direction and includes a base body and an elastic layer covering the base body and having a width in a longitudinal direction of the developer bearing member that accommodates the entire region of the cleaning member in the longitudinal direction. In the longitudinal direction, the cleaning member is disposed at a position where the entire region thereof in the longitudinal direction is accommodated in the width of the elastic layer.