Charging Roll Bias Timing for Precise Nip Width Estimation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing image forming systems face challenges in accurately estimating the nip width of the charging unit to the image carrier, leading to issues such as poor rotation of the charging roll, increased adherence of external additives, and charging failures that result in fog toner formation.

Innovation Solution

The system includes a charging unit that rotates in contact with the image carrier, a pressing member to generate a nip width, and a developing unit, with a processor configured to adjust the charging unit's potential with a rectangular wave during specific times to ensure the image carrier's surface potential is higher than the developing potential, allowing for precise nip width estimation and reduced fog toner formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the charging unit rotates in contact with the image carrier to charge the surface, then charging function is achieved, but accurate estimation of nip width becomes difficult leading to poor rotation and increased external additive adherence

Engineering Contradiction:

Improvecharging reliabilityVSAvoidnip width measurement precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces a pressing member as an intermediary element between the charging unit and image carrier. This pressing member applies controlled pressure to maintain consistent contact and generate a stable nip width, enabling accurate estimation while ensuring reliable charging function. The pressing member mediates the interaction to prevent poor rotation and external additive adherence.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the nip width of charging unit to image carrier is not accurately controlled, then charging function is maintained, but external additives adhere more and charging failures occur resulting in fog toner formation

Engineering Contradiction:

Improvecharging uniformityVSAvoidfog toner formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the potential of the charging unit using rectangular wave modulation during specific time periods. This controls the surface potential of the image carrier to be higher than the developing potential, preventing external additive adherence and charging failures that would otherwise produce fog toner.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the charging unit potential is increased with rectangular wave for set time, then surface potential control is improved and fog toner is reduced, but energy consumption increases

Engineering Contradiction:

Improvesurface potential control precisionVSAvoidcharging unit energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements periodic action by applying rectangular wave potential modulation only during specific time periods when the charging unit contacts the image carrier. This time-limited application achieves precise surface potential control to prevent fog toner while minimizing energy consumption by not continuously applying high potential.

Inventive Principle:

Principle #19Periodic action

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 enables accurate prediction of the nip width, reducing the adherence of external additives and minimizing charging failures, thereby improving the reliability and quality of image formation.

Implementation Method 1

a charging unit that rotates while being in contact with the image carrier and charges a surface of the image carrier by applying a charging bias

Methodology Applied

Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 2

a pressing member that presses the charging unit against the image carrier such that a nip width is generated

Methodology Applied

Scientific EffectMechanical pressure: Mechanical Force

Implementation Method 3

increase an absolute value of a potential of the charging unit with a rectangular wave only for a set time during which instantaneous discharge occurs before and after the nip width

Methodology Applied

Scientific EffectElectrical discharge: Electrostatic Discharge

Data Source

PatentUS20260064026A1Image forming system

Publication Date: 2026.03.05 FUJIFILM BUSINESS INNOVATION CORP

AI summary

An image forming system includes an image carrier that rotates, a charging unit that rotates while being in contact with the image carrier and charges a surface of the image carrier by applying a charging bias, a pressing member that presses the charging unit against the image carrier such that a nip width is generated, a developing unit that develops a latent image formed on the surface of the image carrier with toner, and at least one processor, in which the processor is configured to, in a state in which an absolute value of a surface potential of the image carrier charged by the charging unit is lower than an absolute value of a developing potential of the developing unit, increase an absolute value of a potential of the charging unit with a rectangular wave only for a set time during which instantaneous discharge occurs before and after the nip width of the charging unit to the image carrier and no discharge occurs at a center of the nip width such that the absolute value of the surface potential of the image carrier is higher than the absolute value of the developing potential.