Transfer Voltage Control in Contact Development to Suppress Fogging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In image forming apparatuses with a contact developing system, fogging occurs due to the inability to maintain an appropriate potential difference between the photosensitive drum and the developing roller during post-rotation control when a recording medium is conveyed, leading to toner transfer to non-image forming areas.

Innovation Solution

An image forming apparatus with a control system that applies a first transfer voltage when a recording medium is sandwiched between the image bearing member and the transfer member, followed by a second, lower transfer voltage after the medium passes through the sandwiching portion, to control the potential difference between the photosensitive drum and the developing roller during post-rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If post-rotation control is started while a recording medium is being conveyed by the photosensitive drum and transfer roller, then the rotation time of the photosensitive drum is reduced, but the transfer current increases and fogging occurs due to inability to maintain appropriate potential difference

Engineering Contradiction:

Improverotation time of photosensitive drumVSAvoidpotential difference control during post-rotation

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent applies dynamics by making the transfer voltage adjustable during post-rotation control. The transfer voltage applying portion changes the transfer voltage based on the rotational position of the photosensitive drum, allowing the system to adapt to different operational phases. This dynamic adjustment enables the system to maintain appropriate potential difference even when post-rotation control starts during medium conveyance, thus resolving the contradiction between reduced rotation time and reliable potential difference control.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the transfer voltage parameter during post-rotation control based on the rotational position of the photosensitive drum. By adjusting the transfer voltage dynamically, the system can control the potential difference between the photosensitive drum and transfer roller, preventing fogging while allowing post-rotation control to start during medium conveyance. This parameter change approach directly addresses the contradiction by modifying the electrical parameters to maintain control reliability.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the developing roller and photosensitive drum remain in constant contact, then the developing system is simple, but fogging occurs due to toner transfer to non-image forming portions

Engineering Contradiction:

Improvecontact developing system structureVSAvoidfogging

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the electrical parameters (transfer voltage and potential difference) during post-rotation control to prevent fogging while maintaining the simple contact developing structure. By dynamically adjusting the transfer voltage based on the rotational position of the photosensitive drum, the system can control the potential difference to prevent toner transfer to non-image forming portions, thus resolving the contradiction between structural simplicity and fogging prevention.

Inventive Principle:

Principle #35Parameter changes

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 fogging by maintaining the potential difference within an appropriate range, reducing the rotation time of the photosensitive drum, and extending its lifespan.

Implementation Method 1

a transfer member which transfers a developer image formed on the surface of the image bearing member onto a recording medium by sandwiching the recording medium with the image bearing member at a sandwiching portion

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 2

a charging member which charges a surface of the image bearing member

Methodology Applied

Scientific EffectElectrostatic charging: Electrostatics

Implementation Method 3

the control portion controls the transfer voltage applying portion so as to apply a first transfer voltage to the transfer member in a case that the recording medium is being sandwiched between the image bearing member and the transfer member, and ii) the control portion controls the transfer voltage applying portion so as to apply a second transfer voltage to the transfer member that is lower than the first transfer voltage after the recording medium passes through the sandwiching portion

Methodology Applied

Scientific EffectPotential difference control: Electrostatics

Data Source

PatentUS12554211B2Image forming apparatus

Publication Date: 2026.02.17 CANON KK

AI summary

In post-rotation control of removing an electric charge from a surface of an image bearing member in a state that the image bearing member and a developing member rotate while in contact with each other, in a case that the post-rotation control is started in a state that a recording medium is being conveyed by the image bearing member and a transfer member, i) a control portion controls a transfer voltage applying portion so as to apply a first transfer voltage in a case that the recording medium is being sandwiched between the image bearing member and the transfer member, and ii) the control portion controls the transfer voltage applying portion so as to apply a second transfer voltage that is lower than the first transfer voltage after the recording medium passes through a sandwiching portion.