Primary Transfer Roller Overlap 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 configuration of the primary transfer roller and photoconductor drum is adjusted such that the downstream portion of the first contact region on the drum overlaps with the upstream portion of the second contact region on the roller, stabilizing pressure and preventing image defects without increasing the spring load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the primary transfer roller is offset to the downstream side of the photoconductor drum, then the rotational alignment is simplified, but the pressure in the nip region becomes unstable causing toner splashing and discharge craters
Solution Approach 1:
The patent applies local quality by creating an overlapping region where the first contact region (photoconductor drum) and second contact region (primary transfer roller) partially overlap in the moving direction of the intermediate transfer belt. This localized overlap zone concentrates the pressure stabilization function to a specific area, ensuring stable toner transfer while allowing the rollers to remain rotationally offset. The overlapping region acts as a dedicated zone for pressure equilibrium, resolving the contradiction between simplified alignment and transfer stability.
2Reliability
If the spring load on the primary transfer roller is increased to stabilize pressure, then transfer performance improves, but the mechanical service life of the photoconductor drum and intermediate transfer belt decreases
Solution Approach 1:
The patent changes the geometric parameter of the contact regions by creating an overlap in the moving direction between the first contact region and second contact region. This parameter change allows the system to achieve stable pressure distribution without increasing the spring load magnitude. The overlapping configuration naturally distributes the contact pressure over a larger area and extends the interaction time, providing stable transfer performance while reducing mechanical stress and extending the service life of components.
3Device complexity
If the contact regions between the intermediate transfer belt and the photoconductor drum/primary transfer roller are separated, then the roller offset is maintained, but pressure instability causes banding and image defects
Solution Approach 1:
The patent merges the first contact region and second contact region by making them partially overlap in the moving direction of the intermediate transfer belt. This merging creates a continuous pressure zone that eliminates the separation between contact regions. The overlapping configuration ensures that the intermediate transfer belt maintains stable contact with both the photoconductor drum and primary transfer roller simultaneously, preventing pressure fluctuations that would cause banding and image defects, while preserving the beneficial roller offset configuration.
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, prevents image defects like banding, and prolongs the mechanical service life of the photoconductor drum and intermediate transfer belt by maintaining stable pressure without excessive load.
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
Data Source
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 that transfers a toner image on the photoconductor drum, therefrom to the intermediate transfer belt. A part of a first contact region between the intermediate transfer belt and the photoconductor drum, and a part of a second contact region between the intermediate transfer belt and the primary transfer roller, are made to overlap with each other, and an offset amount, corresponding to a distance along a moving direction of the intermediate transfer belt, between a rotational center of the photoconductor drum and a rotational center of the primary transfer roller, relative to the overlapping amount, is set to be in a predetermined proper range.