Primary Transfer Roller Layout to Prevent Banding and Drum Ghosts
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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 ghosts.
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 intrusion amount to enhance transfer performance and mechanical durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary transfer roller is offset to the downstream side of the photoconductor drum, then the intermediate transfer belt can be pressed against the photoconductor drum for toner transfer, but toner splashing and discharge craters occur leading to image defects
Solution Approach 1:
The primary transfer roller is intentionally offset asymmetrically to the downstream side of the photoconductor drum in the revolving direction of the intermediate transfer belt. This asymmetric positioning creates a specific spatial relationship between the first contact region (photoconductor drum) and second contact region (primary transfer roller) that prevents toner splashing and discharge craters while maintaining effective toner transfer
Solution Approach 2:
The patent introduces a spatial dimension consideration by positioning the contact regions in a specific longitudinal arrangement along the revolving direction of the intermediate transfer belt. The non-overlapping contact regions are distributed along the belt's path, creating a temporal-spatial separation that prevents harmful electrostatic discharge while maintaining transfer functionality
2Manufacturing precision
If the primary transfer roller presses the intermediate transfer belt against the photoconductor drum, then toner image transfer is achieved, but banding and drum ghosts appear due to overlapping contact regions
Solution Approach 1:
The primary transfer roller is positioned asymmetrically offset to the downstream side, creating non-overlapping first and second contact regions. This asymmetric arrangement ensures that the contact zones are spatially separated along the intermediate transfer belt's path, preventing the formation of banding and drum ghosts while maintaining effective toner transfer
Solution Approach 2:
The intermediate transfer belt serves as a mediator between the photoconductor drum and primary transfer roller. By positioning the contact regions to be non-overlapping along the belt's path, the belt effectively separates the two contact zones, preventing direct interaction that would cause banding and drum ghosts while still enabling toner transfer
3Manufacturing precision
If the primary transfer roller is positioned with non-overlapping contact regions, then image quality improves, but the intrusion amount into the photoconductor drum side must be optimized to maintain sufficient voltage
Solution Approach 1:
The patent optimizes the intrusion amount of the primary transfer roller into the photoconductor drum side as a critical parameter. By carefully controlling this intrusion distance, the system maintains sufficient voltage for effective toner transfer while ensuring the contact regions remain non-overlapping to prevent image defects. This parameter optimization balances image quality and transfer reliability
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 improves image quality by reducing banding and drum ghosts, prolongs the mechanical service life of the photoconductor drum and intermediate transfer belt, and stabilizes toner transfer without increasing the load on the primary transfer roller.
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
Implementation Method 2
The intermediate transfer belt is made to move in contact with 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 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.