Photoconductor Drum and Transfer Roller Layout for Stable Nip Pressure
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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 is configured such that the downstream-side portion of the first contact region on the photoconductor drum overlaps with the upstream-side portion of the second contact region on the primary transfer roller, stabilizing pressure at the nip region without increasing the load on the primary transfer roller, thereby preventing image defects and prolonging the mechanical service life of components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary transfer roller is offset to the downstream side with respect to the photoconductor drum, then the intermediate transfer belt can be pressed against the photoconductor drum for primary transfer, but unstable pressure in the nip region causes toner splashing and discharge craters
Solution Approach 1:
The patent introduces a new spatial dimension by making the primary transfer roller overlap with the photoconductor drum in the width direction (perpendicular to the moving direction of the intermediate transfer belt). This dimensional change allows the roller to apply pressure more effectively across the contact region, stabilizing the nip region pressure and preventing toner splashing and discharge craters while maintaining reliable primary transfer.
2Reliability
If the primary transfer roller is offset to the downstream side, then primary transfer can be achieved, but image defects like banding occur due to unstable pressure
Solution Approach 1:
By positioning the primary transfer roller to overlap with the photoconductor drum in the width direction, the patent creates a more stable and uniform pressure distribution across the contact region. This dimensional adjustment eliminates the unstable pressure conditions that cause banding, thereby improving image quality while preserving the primary transfer function.
3Reliability
If spring load on the primary transfer roller is increased to stabilize pressure, then transfer reliability improves, but mechanical service life of components decreases
Solution Approach 1:
The patent achieves pressure stability not by increasing the magnitude of the spring load, but by changing the spatial configuration - making the primary transfer roller overlap with the photoconductor drum in the width direction. This dimensional change improves pressure distribution and transfer reliability while maintaining moderate load levels, thereby preserving the mechanical service life of the photoconductor drum and intermediate transfer belt.
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 prevents image defects like banding and extends the service life of the photoconductor drum and intermediate transfer belt by maintaining stable pressure without increasing the spring load on the primary transfer roller.
Implementation Method 1
The photoconductor drum carries an electrostatic latent image
Implementation Method 2
with the intermediate transfer belt pressed against the photoconductor drum, thereby transferring the toner image
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.