Hemispherical Toner Additives for Transfer Efficiency

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Solution Overview

Problem

Existing electrophotographic image-forming apparatuses face challenges in improving transferability of toner, particularly in reducing untransferred toner on the photosensitive member during the transferring step.

Innovation Solution

The apparatus includes a first and second image-forming portion with rotatable image-bearing and developer-bearing members, using toner particles with organosilicon protrusions to reduce adhesion strength, and an intermediate transfer member to facilitate efficient transfer to a recording material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a spherical external additive with a large particle diameter is added to reduce adhesion strength and improve transfer efficiency, then transfer efficiency is improved, but the additive moves, separates, or buries during extended operation, causing transfer efficiency to deteriorate

Engineering Contradiction:

Improvetransfer efficiencyVSAvoidconsistency of transfer efficiency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses hemispherical external additives instead of spherical ones. The hemispherical shape with a flat base provides stability during operation, preventing movement, separation, and burial while maintaining the spacer effect that reduces adhesion strength and improves transfer efficiency consistently over extended periods

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent specifies particular parameters for the hemispherical external additives including particle diameter (0.5-5.0 μm), density (2.0-4.0 g/cm³), and adhesion strength to toner particles. By optimizing these parameters, the additive maintains its position and function during extended operation, ensuring consistent transfer efficiency

Inventive Principle:

Principle #35Parameter changes

2Reliability

If external additives with large particle diameter are partially buried to suppress movement and separation, then stability is improved, but transferability becomes insufficient when multiple color toners are collectively transferred

Engineering Contradiction:

Improvestability of external additiveVSAvoidtransferability of multi-color toner

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The hemispherical shape with a flat base provides stability during operation, preventing movement, separation, and burial while maintaining the spacer effect that reduces adhesion strength and improves transfer efficiency consistently over extended periods

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

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 configuration effectively reduces the occurrence of untransferred toner for extended periods, maintaining high secondary transferability and image quality by adjusting the protrusion heights and adhesion rates of toner particles.

Implementation Method 1

it is known that there is a method for improving transfer efficiency by reducing physical adhesion strength between toner and a photosensitive member by a spacer effect of adding a spherical external additive with a large particle diameter

Methodology Applied

Scientific EffectSpacer effect:

Data Source

PatentUS12265340B2Image-forming apparatus

Publication Date: 2025.04.01 CANON KK

AI summary

An image-forming apparatus includes first and second photosensitive drums, first and second image-forming portion including first and second development rollers configured to bear developers composed of first and second toner particles and organosilicon protrusions formed on surfaces of the first and second toner particles, an intermediate transfer member to which a developer image is to be transferred in first and second contact portions in contact with the first and second photosensitive drums, and a transfer member configured to transfer the developer image to a recording material in a transfer portion. The first contact portion is formed downstream of the transfer portion and upstream of the second contact portion in a movement direction of the surface of the intermediate transfer member. A protrusion formed on the second developer has a lower height than a protrusion formed on the first developer.