Toner Blocking Layer Prevents Vertical Streaks

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Solution Overview

Problem

Existing image forming apparatuses face issues with faulty cleaning of photosensitive drums due to excessive toner transfer from intermediate transfer members, leading to vertical streaks in images, especially when a large amount of toner is reversely transferred.

Innovation Solution

The apparatus employs a developer bearing member to supply toner to the image bearing member, which then forms a blocking layer on the cleaning blade, allowing for the collection of toner from the toner charging brush onto the photosensitive drum, preventing faulty cleaning by managing the toner discharge and collection process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If residual transfer toner is reversely transferred onto the photosensitive drum to enable continuous image forming, then productivity is improved, but manufacturing precision deteriorates due to vertical streaks caused by faulty cleaning

Engineering Contradiction:

Improvecontinuous image forming capabilityVSAvoidimage quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The invention applies preliminary action by forming a blocking layer on the photosensitive drum surface before the reverse transfer toner arrives. This blocking layer, created by supplying fresh toner in advance, prevents the reverse transfer toner from directly contacting and damaging the cleaning blade, thereby preventing vertical streaks while maintaining continuous image forming capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses an intermediary approach by introducing a blocking layer as a mediator between the reverse transfer toner and the cleaning blade. This blocking layer acts as a protective intermediary that absorbs the impact of the reverse transfer toner, preventing direct contact with the cleaning blade and eliminating the cause of vertical streaks

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If a large amount of toner is reversely transferred from the intermediate transfer member, then the collection efficiency is improved, but object-generated harmful factors worsen due to destruction of the blocking layer and faulty cleaning

Engineering Contradiction:

Improvetoner collection amountVSAvoidvertical streaks from cleaning blade damage

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The invention applies preliminary action by pre-forming a sufficient blocking layer before large amounts of reverse transfer toner arrive. This blocking layer is created in advance by supplying fresh toner to the photosensitive drum, ensuring it is robust enough to withstand the impact of large quantities of reverse transfer toner without being destroyed, thereby preventing vertical streaks

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention uses beforehand cushioning by creating a blocking layer that acts as a cushion or buffer before the reverse transfer toner contacts the cleaning blade. This blocking layer absorbs and distributes the impact force of large amounts of reverse transfer toner, preventing concentrated forces from damaging the cleaning blade and causing vertical streaks

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution effectively prevents vertical streaks in images by forming a sufficient blocking layer at the cleaning blade edge, ensuring efficient toner collection and maintaining image quality even with high toner transfer amounts.

Implementation Method 1

residual transfer toner on the intermediate transfer member is charged to the opposite polarity to the normal charging state of toner by a toner charging unit so that the residual transfer toner is reversely transferred onto a photosensitive drum

Methodology Applied

Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

The toner reversely transferred onto the photosensitive drum is removed by a cleaning unit such as a cleaning blade

Methodology Applied

Scientific EffectMechanical cleaning: Friction

Implementation Method 3

the developer bearing member supplies second developer to the image bearing member such that the developer from the developer bearing member is supplied to the cleaning member before the developer reversely transferred is supplied to the cleaning member

Methodology Applied

Scientific EffectGravitational flow: Gravitation

Data Source

PatentUS11079712B2Image forming apparatus for an intermediate transfer of a toner image and for reversely transferring collected developer to an image bearing member

Publication Date: 2021.08.03 CANON KK

AI summary

An image forming apparatus including a holding apparatus configured to collect residual developer remaining on an intermediate transfer belt and temporarily hold the residual developer, and a cleaning member configured to remove toner borne on the photosensitive drum that moves the toner held by the holding apparatus to the intermediate transfer belt and discharging the toner. Toner from a development roller is supplied to the cleaning member before toner reversely transferred from the intermediate transfer belt is supplied to the cleaning member.