Secondary Transfer Roller Control for Duplex Print Contamination
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Solution Overview
Problem
In image forming apparatuses with automatic double-sided conveying functions, the formation of sheet-less toner images on the intermediary transfer member leads to contamination of the back surface of sheets due to toner deposition on the secondary transfer roller, reducing productivity during double-sided printing.
Innovation Solution
The apparatus includes a controller that adjusts the interval between back surface printing and immediately-before printing based on predetermined conditions, such as environmental temperature, developing device lifetime, image density, and user designation, and performs a cleaning operation when necessary, to manage toner deposition on the secondary transfer roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet-less toner image is transferred through the secondary transfer portion without interruption, then the productivity is maintained, but the backside contamination occurs due to toner deposition on the secondary transfer roller
Solution Approach 1:
The patent applies a reverse polarity voltage to the secondary transfer roller in advance before the sheet-less toner image reaches the transfer nip. This preliminary action prevents toner deposition on the roller surface before contamination can occur, allowing continuous high-speed printing without stopping for cleaning operations.
Solution Approach 2:
The patent changes the electrical parameter (voltage polarity) of the secondary transfer roller dynamically. By switching from normal transfer polarity to reverse polarity at specific timing, the system controls toner adhesion behavior to prevent deposition while maintaining continuous operation and high productivity.
2Object-affected harmful factors
If the voltage polarity is reversed to prevent backside contamination, then the contamination is reduced, but the productivity decreases due to additional control complexity
Solution Approach 1:
The patent uses detection information about sheet presence and timing feedback to control the voltage polarity switching. The system monitors whether a sheet is present in the transfer path and automatically adjusts the voltage polarity accordingly, creating a simple closed-loop control that prevents contamination without requiring complex manual intervention.
3Object-affected harmful factors
If the toner image is formed with longer interval to allow cleaning, then the backside contamination is prevented, but the productivity is lowered
Solution Approach 1:
The patent maintains continuous printing operation without stopping or extending intervals between prints. By using reverse polarity voltage to prevent toner deposition during the sheet-less transfer, the system keeps the useful action (printing) continuous while preventing contamination, thereby maintaining high productivity.
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 approach effectively reduces backside contamination and maintains productivity by optimizing toner transfer intervals and cleaning operations, ensuring high-quality double-sided printing even in varying conditions.
Implementation Method 1
an intermediary transfer member onto which a toner image formed on the image bearing member is transferred
Implementation Method 2
The sheet-less toner image is deposited on a secondary transfer roller when the sheet-less toner image passes through a secondary transfer portion
Data Source
AI summary
A controller is capable of executing a first operation when a predetermined condition is not satisfied, and a second operation when the predetermined condition is satisfied. The predetermined condition includes at least one of that an environmental temperature is a predetermined temperature or more, that a remaining lifetime of a developing device is less than a predetermined value, that a user designates the second operation, that an image density in the immediately-before printing is a predetermined value or more, that an image in the immediately-before printing includes an image other than a text image, and that a maximum density of a part of a region in immediately-before printing is a predetermined value or more. When detection that there is no sheet corresponding to the objective sheet is made by a detecting portion, a toner image formed by the second operation is transferred onto a re-conveying sheet.