Electrostatic Developer Carrier Coating for Image Density Stability

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Solution Overview

Problem

Existing electrostatic charge image developing carriers with resin coating layers containing inorganic particles face issues with image density stability, particularly in low-temperature and low-humidity environments, due to excessive charging and fluctuations in image density.

Innovation Solution

The carrier includes magnetic particles with a resin coating layer containing inorganic particles, where the element ratio difference (B - A) analyzed by X-ray photoelectron spectroscopy is between 0.5 atm% and 3.0 atm%, with specific conditions on particle size, distribution, and surface treatment to stabilize image density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the resin coating layer contains inorganic particles, then the carrier can be manufactured with standard materials, but image density stability deteriorates due to excessive charging and fluctuations in low-temperature and low-humidity environments

Engineering Contradiction:
Improveease of manufactureVSAvoidimage density stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the element ratio of metals and metalloids in the inorganic particles through X-ray photoelectron spectroscopy analysis. By maintaining the element ratio within 0.5 atm% to 3.0 atm% and controlling the content of inorganic particles at 15-35% by mass, the patent stabilizes image density while preventing excessive charging in low-temperature and low-humidity environments.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining resin particles with inorganic particles in the resin coating layer. This composite structure allows the inorganic particles to provide charging control while the resin matrix maintains coating integrity. The specific composition ratio and particle size distribution (D1/D2 ratio of 0.01 to 0.15) create a synergistic effect that stabilizes image density across varying environmental conditions.

Inventive Principle:
Principle #40Composite materials

2Device complexity

If the element ratio of metals and metalloids in inorganic particles is not controlled, then manufacturing is simpler, but charge fluctuations increase causing image density instability

Engineering Contradiction:
Improvedevice complexityVSAvoidimage density stability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces mechanical mixing and sorting methods with analytical techniques (X-ray photoelectron spectroscopy) to control the element ratio of inorganic particles. This substitution allows precise control of metal and metalloid content (maintaining B-A between 0.5 atm% and 3.0 atm%) without complex mechanical separation processes, achieving both simplicity and precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements feedback control by specifying the element ratio range (0.5 atm% to 3.0 atm%) as a control parameter. This feedback mechanism ensures that the inorganic particles maintain appropriate metal and metalloid content throughout the coating layer, preventing charge fluctuations and image density instability while guiding the manufacturing process.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If inorganic particles are not appropriately exposed on the surface, then the coating is more uniform, but charge control capability decreases leading to abnormal charge fluctuations

Engineering Contradiction:
Improvecoating uniformityVSAvoidcharge control capability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies local quality by creating different particle distributions at different depths of the resin coating layer. The inorganic particles are strategically positioned to be appropriately exposed on the surface (providing charge control capability) while maintaining overall coating uniformity. The particle size ratio (D1/D2 of 0.01 to 0.15) ensures that inorganic particles are distributed to provide surface exposure without compromising coating uniformity.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent uses parameter changes by controlling the particle size distribution of inorganic particles (D1 between 1 nm to 100 nm) and their concentration (15-35% by mass). These parameter adjustments ensure that inorganic particles are appropriately exposed on the surface to provide charge control capability while maintaining coating uniformity and preventing abnormal charge fluctuations.

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

The solution provides enhanced image density stability by appropriately exposing inorganic particles on the surface, preventing abnormal charge fluctuations, especially in varying environmental conditions.

Implementation Method 1

in a case where an element ratio of metals and metalloids, that constitute the inorganic particles, is analyzed by X-ray photoelectron spectroscopy in a depth direction

Methodology Applied
Scientific EffectX-ray photoelectron spectroscopy: Photoelectric Effect

Data Source

PatentEP4600749A1Electrostatic charge image developing carrier, electrostatic charge image developer, process cartridge, image forming apparatus, and image forming method
Publication Date: 2025.08.13 FUJIFILM BUSINESS INNOVATION CORP
  • EP4600749A1 patent drawingFigure 1
  • EP4600749A1 patent drawingFigure 2
  • EP4600749A1 patent drawing

AI summary

An electrostatic charge image developing carrier includes magnetic particles and a resin coating layer that coats the magnetic particles, in which the resin coating layer contains inorganic particles, and in a case where an element ratio of metals and metalloids, that constitute the inorganic particles, is analyzed by X-ray photoelectron spectroscopy in a depth direction, and the element ratio at 0 seconds of etching is defined as A and the element ratio at 300 seconds of etching is defined as B, a value of B - A is 0.5 atm% or more and 3.0 atm% or less.