Toner Form Factor and Cleaning Pressure for Image Quality

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Solution Overview

Problem

Current image forming technologies face challenges in producing high-quality images with minute dot reproducibility due to poor cleaning performance, particularly with toner particles of small size and sharp particle size distribution, which lead to issues like background fouling and streaks during the cleaning process.

Innovation Solution

An image forming apparatus and process cartridge that utilize a toner with a modified laminar inorganic mineral, granulated in an aqueous phase, and a specific form factor, along with a cleaning device with an elastic member applying pressure between 2 to 6 MPa, to enhance cleaning performance and prevent toner slipping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If toner particles of small size and sharp particle size distribution are used, then minute dot reproducibility is improved, but cleaning performance deteriorates causing background fouling and streaks

Engineering Contradiction:
Improveminute dot reproducibilityVSAvoidcleaning performance
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention applies local quality by creating toner particles with non-uniform surface properties through controlled aggregation. The primary particles (0.5-2 μm) aggregate to form larger particles (3-8 μm) with irregular surfaces that have different local characteristics - some areas are rough and aggregate-prone while others are smoother, enabling both good image formation and cleaning performance

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention uses nesting by having primary particles nested within aggregated structures. The hierarchical structure consists of smaller primary particles (0.5-2 μm) that are bound together to form larger aggregated particles (3-8 μm), creating a nested architecture that provides both the fineness needed for minute dot reproduction and the irregular surface needed for blade cleaning

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If inorganic filler is added to make toner form irregular, then blade cleaning performance is improved, but cleaning blade abrasion increases

Engineering Contradiction:
Improveblade cleaning performanceVSAvoidcleaning blade abrasion
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention replaces the durable but abrasive inorganic filler with organic aggregate structures that are less harmful to the blade. The organic material in the aggregates acts as a sacrificial element that protects the blade from abrasion while still providing the irregular surface needed for cleaning, effectively using a softer, blade-friendly material in place of hard inorganic filler

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention creates composite toner particles by aggregating multiple primary particles together. This composite structure of bound primary particles forms irregular surfaces that aid cleaning while the organic nature of the aggregates reduces blade abrasion compared to inorganic fillers, combining the benefits of irregular form with blade protection

Inventive Principle:
Principle #40Composite materials

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 solution achieves improved cleaning performance and reduces blade abrasion, ensuring high-quality images with minute dot reproducibility and stable transfer efficiency by optimizing the toner's form factor and the cleaning process.

Implementation Method 1

a cleaning device with an elastic member applying pressure between 2 to 6 MPa

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the toner is granulated in an aqueous phase

Methodology Applied
Scientific EffectGranulation in aqueous phase:

Data Source

PatentEP1903403B1Image forming apparatus and process cartridge
Publication Date: 2015.11.04 RICOH CO LTD
  • EP1903403B1 patent drawingFigure 1
  • EP1903403B1 patent drawingFigure 2A~2C
  • EP1903403B1 patent drawingFigure 3~4

AI summary

An image forming apparatus including an image bearing member to bear a latent electrostatic image, a charging member to charge a surface of the image bear ing member, an irradiation member to irradiate the image bearing member to write the latent electrostatic image, a development member to develop the latent electrostatic image with a toner to form a visualized image, a transfer device to transfer the visualized image directly or via an intermediate transfer body to a recording medium, a fixing device to fix the transferred image transferred on the recording medium and a cleaning device to remove residual toner remaining on the image bearing member. In the image forming apparatus, the cleaning device includes an elastic member having a blade form a front end of which is in contact with the image bearing member with a pressure of from 2 to 6 MPa and the toner is granulated in an aqueous phase and contains a laminar inorganic mineral having ions between layers at least part of which is modified by an organic ion and the average form factor SF-1 of the toner is from 130 to 160.