Primary Transfer Roller Layout for Stable Toner Transfer

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Solution Overview

Problem

Existing electrophotographic image forming apparatuses face issues with toner splashing and discharge craters due to the primary transfer roller being offset to the downstream side of the photoconductor drum, leading to inefficient toner transfer and potential image defects like banding and drum ghosting.

Innovation Solution

The primary transfer roller is designed to intrude into the side of the photoconductor drum via the intermediate transfer belt, with non-overlapping contact regions to maintain sufficient voltage for toner transfer and prevent flapping of the intermediate transfer belt, while optimizing pressure and load on the components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the primary transfer roller is offset to the downstream side of the photoconductor drum, then the toner transfer can be maintained, but toner splashing and discharge craters occur leading to image defects

Engineering Contradiction:

Improvetoner transfer stabilityVSAvoidtoner splashing and discharge craters

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by offsetting the primary transfer roller from the rotational center of the photoconductor drum to the upstream side. This asymmetric positioning creates a specific geometric relationship where the contact region between the intermediate transfer belt and photoconductor drum does not overlap with the contact region between the intermediate transfer belt and primary transfer roller. This asymmetric configuration prevents toner splashing and discharge craters while maintaining effective toner transfer.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent introduces a spatial dimension solution by positioning the primary transfer roller on the upstream side rather than directly opposite or downstream. This dimensional repositioning in the rotational direction creates non-overlapping contact regions, effectively separating the toner transfer zones and preventing harmful toner splashing and discharge phenomena.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If the primary transfer roller presses the intermediate transfer belt against the photoconductor drum, then toner transfer is achieved, but mechanical wear and load increase reducing service life

Engineering Contradiction:

Improvetoner transfer efficiencyVSAvoidservice life of photoconductor drum and intermediate transfer belt

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies preliminary action by positioning the primary transfer roller's contact region upstream of the photoconductor drum's contact region. This upstream positioning allows the toner transfer to occur in advance before the belt reaches the photoconductor drum's main contact zone, reducing the mechanical load and wear on both the photoconductor drum and intermediate transfer belt while maintaining transfer efficiency.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If the contact regions overlap, then the structure is simplified, but voltage insufficient for toner transfer and belt flapping occur

Engineering Contradiction:

Improvestructural complexityVSAvoidtoner transfer voltage sufficiency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent uses asymmetry to create non-overlapping contact regions by positioning the primary transfer roller upstream. This asymmetric arrangement naturally separates the electrical interaction zones, ensuring sufficient voltage for toner transfer without requiring complex additional structures, thereby maintaining simplicity while improving reliability.

Inventive Principle:

Principle #4Asymmetry

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 enhances toner transfer performance, reduces image defects, and prolongs the mechanical service life of the photoconductor drum and intermediate transfer belt by stabilizing pressure and load distribution.

Implementation Method 1

The primary transfer roller is opposed to the photoconductor drum via the intermediate transfer belt, and presses the intermediate transfer belt against the photoconductor drum, thereby transferring the toner image on the photoconductor drum, to the intermediate transfer belt from the photoconductor drum

Methodology Applied

Scientific EffectElectrostatic transfer: Electrostatic Induction

Data Source

PatentUS20260093192A1Image forming apparatus including photoconductor drum and primary transfer roller

Publication Date: 2026.04.02 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

An image forming apparatus includes a photoconductor drum, an intermediate transfer belt that moves in contact with the photoconductor drum, and a primary transfer roller which is a metal roller. A first contact region, being a region on the photoconductor drum in contact with the intermediate transfer belt, and a second contact region, being a region on the primary transfer roller in contact with the intermediate transfer belt, are spaced from each other, and a summit of the primary transfer roller, protruding farthest toward the photoconductor drum, in a direction in which the photoconductor drum and the primary transfer roller are aligned across the intermediate transfer belt, is set to intrude on the photoconductor drum, via the intermediate transfer belt.