Primary Transfer Roller Offset 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 unstable pressure in the nip region and potential image defects like banding.
Innovation Solution
The apparatus design includes overlapping portions of the first and second contact regions between the photoconductor drum and the primary transfer roller, with the primary transfer roller's rotational center offset downstream, to stabilize pressure and prevent image defects without increasing the spring load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the primary transfer roller is offset to the downstream side of the photoconductor drum, then toner splashing and discharge craters are prevented, but unstable pressure in the nip region causes banding and image defects
Solution Approach 1:
The patent applies local quality by creating an overlapping region where the first contact region (photoconductor drum with intermediate transfer belt) and second contact region (primary transfer roller with intermediate transfer belt) intersect. This localized overlap zone concentrates the pressure stabilization function precisely where needed - in the nip region between the photoconductor drum and primary transfer roller - without requiring global system changes or increased spring load across the entire transfer mechanism.
Solution Approach 2:
The patent merges the functions of the first contact region and second contact region by making them overlap spatially. This combination creates a unified pressure distribution zone that simultaneously handles both the photoconductor drum-to-belt transfer and the primary transfer roller-to-belt transfer, stabilizing pressure in the critical nip region and preventing banding while maintaining the downstream offset configuration.
2Reliability
If spring load is increased to stabilize pressure in the nip region, then banding is prevented, but mechanical stress on photoconductor drum and intermediate transfer belt increases
Solution Approach 1:
The overlapping contact regions create a localized pressure stabilization zone that precisely targets the nip region without requiring increased spring load. This localised approach stabilizes pressure where it matters most (in the nip region between photoconductor drum and primary transfer roller) while avoiding the need to increase mechanical stress on the entire intermediate transfer belt and photoconductor drum system.
3Productivity
If the primary transfer roller is positioned downstream of the photoconductor drum, then transfer performance is improved, but contact regions do not overlap causing unstable pressure distribution
Solution Approach 1:
The patent resolves the contradiction by introducing a spatial dimension - specifically, creating an overlapping region in the contact zones. By making the first contact region and second contact region overlap in the longitudinal direction (along the intermediate transfer belt), the patent adds a dimensional relationship between the contact regions that simultaneously achieves both downstream positioning for good transfer performance and pressure stabilization through overlap.
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 transfer performance, improves image quality by preventing banding, and prolongs the mechanical service life of the photoconductor drum and intermediate transfer belt by stabilizing pressure and reducing mechanical stress.
Implementation Method 1
The primary transfer roller is opposed to the photoconductor drum via the intermediate transfer belt, and rotates in a moving direction of the intermediate transfer belt, with the intermediate transfer belt pressed against the photoconductor drum, thereby transferring the toner image on the photoconductor drum, to the intermediate transfer belt from the photoconductor drum
Data Source
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AI summary
An image forming apparatus (1) includes a photoconductor drum (4), an intermediate transfer belt (5) that moves in contact with the photoconductor drum (4), and a primary transfer roller (31) that transfers a toner image on the photoconductor drum (4), therefrom to the intermediate transfer belt (5). A part of a first contact region (4S) between the intermediate transfer belt (5) and the photoconductor drum (4), and a part of a second contact region (1S) between the intermediate transfer belt (5) and the primary transfer roller (31), are made to overlap with each other, and an offset amount (F), corresponding to a distance along a moving direction (A) of the intermediate transfer belt (5), between a rotational center of the photoconductor drum (4) and a rotational center of the primary transfer roller (31), relative to the overlapping amount, is set to be in a predetermined proper range.