Spherical Resin Particles Suppress Electrostatic Memory in Developing Devices

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Solution Overview

Problem

The existing developing devices in electrophotographic apparatuses tend to generate electrostatic memory during transportation vibrations, leading to banding issues in electrophotographic images, particularly in halftone images, due to direct contact and uneven distribution of particles between the developing roller and the toner regulating member.

Innovation Solution

The use of spherical resin particles with specific Martens hardness (0.5 N/mm² to 45 N/mm²) and high restoring elastic power (70% or higher) between the developing roller and the toner regulating member, which absorb and recover from vibrations without applying physical stress, preventing direct contact and uneven distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the developing device is transported for long time, then the developing roller and toner regulating member are in direct contact, but this causes electrostatic memory and banding in images

Engineering Contradiction:
Improveimage qualityVSAvoidelectrostatic memory
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Spherical resin particles are introduced as an intermediary substance between the developing roller and toner regulating member. These particles prevent direct contact during transportation, thereby eliminating the cause of electrostatic memory while maintaining necessary contact during actual development operations.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical state of the contact interface by introducing particles with specific properties (spherical shape, controlled Martens hardness between 0.5-45 N/mm², and high restoring elastic power ≥70%). These parameter specifications ensure the particles can withstand compression during transportation while recovering to maintain uniform toner distribution.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If particles are provided between the developing roller and toner regulating member, then direct contact is prevented, but particle distribution uniformity must be maintained

Engineering Contradiction:
Improvedirect contact damageVSAvoidparticle distribution uniformity
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

Specific particle properties are defined to prevent clumping and ensure uniform distribution: spherical shape promotes even scattering, controlled hardness (0.5-45 N/mm²) prevents deformation, and high restoring elastic power (≥70%) ensures particles return to original position after compression, maintaining uniform distribution during both transportation and development.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The spherical resin particles are specifically applied to the contact portion between the developing roller and toner regulating member, providing localized protection only where needed during transportation, while allowing normal operation elsewhere in the developing device.

Inventive Principle:
Principle #3Local quality

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 solution effectively suppresses the generation of thrust memory, reducing banding in electrophotographic images and ensuring high-quality image output even after long-time transportation vibrations.

Implementation Method 1

spherical resin particles having a Martens hardness within a range of 0.5 N/mm² to 45 N/mm² and a restoring elastic power of 70% or more

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

even if the developing device that is yet to be used is vibrated during long-time transportation

Methodology Applied
Scientific EffectVibration: Vibration

Data Source

PatentEP2818937B1Developing device, process cartridge, and electrophotographic apparatus
Publication Date: 2017.07.19 CANON KK
  • EP2818937B1 patent drawingFigure 1
  • EP2818937B1 patent drawingFigure 2
  • EP2818937B1 patent drawingFigure 3~4

AI summary

A developing device includes a developing chamber (102) provided with a developing roller (106) that conveys toner (103) to a developing area, and a toner regulating member (109) that is in contact with a surface of the developing roller; and a toner container (104) that contains the toner. An opening that allows the developing chamber and the toner container to communicate with each other is closed by a removable seal member (105) that prevents the toner in the toner container from flowing into the developing chamber. Spherical resin particles (120) are provided at least in a contact portion between the developing roller and the toner regulating member. A Martens hardness of the spherical resin particles is 0.5 N/mm2 or higher and 45 N/mm2 or lower, and a restoring elastic power of the spherical resin particles is 70% or higher.