Electrophotographic Toner Charge Control to Prevent Long-Term Fogging
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Solution Overview
Problem
Image forming apparatuses using electrophotographic methods experience fogging issues due to the migration of external additives, leading to reduced charge quantity of toner and subsequent image defects over long-term use.
Innovation Solution
The use of a positive external additive, such as strontium titanate, to control the charge quantity of toner, combined with specific voltage control strategies to manage the adhesion of additives, prevents fogging by maintaining optimal toner charge levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external additives are used to stabilize charging performance, then fogging is suppressed initially, but the external additive migrates to non-image regions during long-term use, reducing toner charge quantity and worsening fogging
Solution Approach 1:
The patent recovers external additives that have migrated to non-image regions by applying reverse polarity voltage to attract them back to the toner, and replenishes them through the charging member to maintain stable charging performance and prevent fogging during long-term use
2Quantity of substance
If external additive amount is increased to maintain charge quantity, then fogging is reduced, but the migration effect is enhanced and charge quantity control becomes difficult
Solution Approach 1:
The patent applies reverse polarity voltage to the charging member to create a feedback mechanism that attracts migrated external additives back to the toner, automatically maintaining optimal charge quantity and preventing fogging without manual intervention
Solution Approach 2:
The patent changes the voltage polarity parameter during different operational phases: normal polarity during image formation and reverse polarity during non-image formation to control external additive distribution and maintain stable charge quantity
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 maintains good image quality over extended use by preventing toner adherence to non-image regions, thereby reducing fogging and ensuring consistent print quality.
Implementation Method 1
a charging voltage is applied to the charging member in a non-image formation period, thereby generating an electrostatic force that acts on the external additive having a charge polarity opposite to that of the toner
Implementation Method 2
generating an electrostatic force that acts on the external additive having a charge polarity opposite to that of the toner, thereby transporting the external additive to the developer
Data Source
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AI summary
An image forming apparatus is characterized by that a region of the surface of an image bearing member in which a second potential difference that generates an electrostatic force such that developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the image bearing member to a developer bearing member was generated in a second operation that moves the developer from the surface of the image bearing member to the developer bearing member includes a region where a first potential difference that generates an electrostatic force such that the developer which is charged to an opposite polarity to the normal charging polarity of the developer moves from the charging member to the image bearing member was generated in a first operation that moves the developer from the surface of the charging member to the surface of the image bearing member.