Developing Unit Electric Field Layout for Floating Toner Collection

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Solution Overview

Problem

Existing developing devices face challenges in efficiently collecting both normal and reverse polarity toners due to the limitations of electric fields, leading to leakage of floating toner outside the device.

Innovation Solution

A developing device design incorporating a developer holder, a first member on the downstream side, and a second member with an intermediate potential applied between the developer holder and the first member, along with magnets forming a brush towards the center direction, and specific angle and distance configurations to enhance collection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an electric field is used to collect normal electrode toner, then normal electrode toner collection is improved, but reverse polarity toner cannot be collected

Engineering Contradiction:
Improvetoner collection efficiencyVSAvoidability to collect both normal and reverse polarity toner
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

A second member with intermediate potential is introduced between the developer holder and the first member. This intermediary component creates multiple electric field zones: one between the developer holder and the second member that collects normal electrode toner, and another between the second member and the first member that collects reverse polarity toner. This resolves the contradiction by enabling collection of both toner types through a mediating structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The collection space is segmented into multiple zones by introducing the second member with intermediate potential. Instead of a single electric field, the system creates separate collection zones: the first zone collects normal electrode toner toward the developer holder, while the second zone collects reverse polarity toner toward the first member. This segmentation allows simultaneous collection of both toner types.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If a single electric field is applied between developer holder and first member, then device structure is simple, but floating toner leakage occurs

Engineering Contradiction:
Improveelectric field configurationVSAvoidfloating toner leakage
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The second member with intermediate potential serves as a mediator that prevents floating toner leakage. By creating an intermediate potential zone, it establishes additional electric field boundaries that contain both normal and reverse polarity toner, preventing them from becoming floating toner and leaking outside the device.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If intermediate potential is applied to the second member, then reverse polarity toner collection is improved, but device complexity increases

Engineering Contradiction:
Improvereverse polarity toner collectionVSAvoidelectric field configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The second member acts as an intermediary component that enables reverse polarity toner collection without requiring a completely complex system redesign. By simply introducing this intermediate potential member, the system creates the necessary electric field zones for collecting both toner types effectively.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

The design effectively collects floating toner, reduces leakage, and improves the efficiency of developer adherence, particularly for reverse polarity toner, compared to traditional electric field collection methods.

Implementation Method 1

an intermediate potential as a potential between a potential applied to the developer holder and a potential applied to the first member is applied

Methodology Applied
Scientific EffectElectric field: Electric Field

Implementation Method 2

a magnet for forming a brush containing the carrier of the developer

Methodology Applied
Scientific EffectMagnetic field: Magnetic Field

Data Source

PatentEP4530736B1Developing device and image forming apparatus
Publication Date: 2026.01.21 FUJIFILM BUSINESS INNOVATION CORP
  • EP4530736B1 patent drawingFigure 1
  • EP4530736B1 patent drawingFigure 2
  • EP4530736B1 patent drawingFigure 3A~3C

AI summary

A developing device includes a developer holder that holds a developer containing toner and carrier and being supplied to an image holder forming an electrostatic latent image; a first member that is provided on a downstream side of a developing position that is a position where the developer held by the developer holder is supplied to the image holder; and a second member that is provided between the developer holder, the image holder, and the first member, that has a surface facing the developer holder, and to which an intermediate potential as a potential between a potential applied to the developer holder and a potential applied to the first member is applied.