Brush Member Voltage Control for Toner Dispersion in Image Forming Apparatus

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Solution Overview

Problem

In electrophotographic image forming apparatuses, the transfer residual toner is not uniformly dispersed during the cleaning operation, leading to improper charging of the photosensitive member, causing image defects such as density non-uniformity due to toner agglomeration with paper powder impurities.

Innovation Solution

An image forming apparatus with a controller that manages a cleaning operation by creating a potential difference between the transfer member and the photosensitive member to move toner charged to a normal polarity towards the photosensitive member, and another potential difference between the brush member and the photosensitive member to move toner towards the brush member, ensuring uniform deposition and separation of toner and impurities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a brush member is provided to disperse transfer residual toner on the photosensitive member, then the toner dispersion is improved, but during cleaning operation the toner moved from the transfer member is non-uniformly deposited on the charging member causing improper charge

Engineering Contradiction:

Improvetoner dispersion uniformityVSAvoidcharging uniformity

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The invention applies a voltage to the brush member to create an electric field that dynamically controls toner movement. This dynamic control ensures that toner moved from the transfer member during cleaning operation is uniformly deposited on the charging member, preventing improper charge while maintaining the brush member's dispersing function during normal operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the electrical parameter (voltage) of the brush member to control toner deposition behavior. By applying an appropriate voltage, the brush member can uniformly deposit toner on the charging member during cleaning operation, resolving the contradiction between toner dispersion and charging uniformity

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If cleaning operation moves toner from transfer member to photosensitive member, then transfer member is cleaned, but toner is non-uniformly deposited on charging member causing image density non-uniformity

Engineering Contradiction:

Improvetransfer member cleaningVSAvoidimage density uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention uses a dynamically controllable electric field applied to the brush member to guide toner movement during cleaning operation. This ensures uniform toner deposition on the charging member, preventing image density non-uniformity while effectively cleaning the transfer member

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention replaces the purely mechanical brush contact system with an electrostatic control system. By applying voltage to the brush member, toner movement is controlled through electric field forces rather than just mechanical action, achieving uniform deposition and preventing charging irregularities

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 approach effectively suppresses improper charging and image defects by ensuring the toner and impurities are separated and collected efficiently, preventing toner agglomeration and maintaining image quality.

Implementation Method 1

a first operation in which a potential difference is formed between the transfer member and the photosensitive member so that the toner charged to the normal charge polarity is moved from the transfer member toward the photosensitive member, and a second operation in which a potential difference is formed between the brush member and the photosensitive member so that the toner charged to the normal charge polarity is moved from the photosensitive member toward the brush member

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS12124183B2Image forming apparatus capable of suppressing an improper charge resulting from toner being moved from a transfer member to a photosensitive member

Publication Date: 2024.10.22 CANON KK

AI summary

An image forming apparatus includes a photosensitive member, a charging member, an electrostatic image forming portion, a developing member, a transfer member, a transfer voltage source, a brush member, a brush voltage source, and a controller capable of executing a cleaning operation. The controller carries out control so that the cleaning operation includes a first operation in which a potential difference is formed between the transfer member and the photosensitive member so that toner charged to a normal charge polarity is moved from the transfer member toward the photosensitive member, and a second operation in which a potential difference is formed between the brush member and the photosensitive member so that the toner charged to the normal charge polarity is moved from the photosensitive member toward the brush member.