Transfer Roller Bias Control for Ionic Polarization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ion-conductive transfer rollers in electrophotographic image forming apparatuses experience ionic polarization due to continuous application of transfer bias, leading to deterioration and charge history on the photosensitive drum, resulting in toner image concentration differences and the need for prolonged post-aging.
Innovation Solution
An image forming apparatus with a control section that manages the application of reverse bias to the transfer roller during double-sided printing, ensuring the reverse bias is applied after the recording medium passes through the toner image transfer position and is re-conveyed, while maintaining the transfer bias application over one revolution of the photosensitive drum, thereby reducing ionic polarization and eliminating charge history.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse bias is applied to the transfer roller in intervals between recording paper sheets to reduce ionic polarization, then transfer roller deterioration is prevented, but charge history remains on the photosensitive drum surface causing toner image concentration differences
Solution Approach 1:
The patent applies reverse bias periodically during double-sided printing operations - specifically when the recording medium is being re-conveyed after passing through the transfer position. This periodic application reduces ionic polarization and prevents transfer roller deterioration while minimizing charge history effects on the photosensitive drum, as the reverse bias is applied only during specific intervals rather than continuously.
2Reliability
If reverse bias is applied to the transfer roller to prevent deterioration, then ionic polarization is reduced, but post-aging time must be extended to eliminate charge history
Solution Approach 1:
By applying reverse bias periodically during double-sided printing operations rather than requiring extended post-aging time, the patent eliminates ionic polarization effects during the printing process itself. The control section timing the reverse bias application to coincide with recording medium re-conveyance allows the system to maintain transfer roller durability without extending post-aging time.
3Productivity
If transfer bias is continuously applied to the transfer roller, then toner image transfer is maintained, but ionic polarization accumulates causing transfer roller resistance increase
Solution Approach 1:
The patent maintains continuous printing capability by applying transfer bias during active transfer operations while periodically applying reverse bias during double-sided printing re-conveyance intervals. This periodic alternation prevents ionic polarization accumulation and maintains transfer roller electrical conduction without interrupting the continuous printing process.
Solution Approach 2:
The patent changes the electrical parameter (bias polarity) applied to the transfer roller based on operational phase - using transfer bias (reverse polarity to toner charge) during active transfer and reverse bias (same polarity as toner charge) during re-conveyance intervals in double-sided printing. This parameter change prevents ionic polarization while maintaining 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 reduces the time required for post-aging and prevents transfer roller deterioration while maintaining the reduction of ionic polarization, ensuring consistent toner image transfer without surface potential differences on the photosensitive drum.
Implementation Method 1
a transfer bias of reverse polarity to charge of toner forming the toner image to be transferred is applied from its transfer bias applying section to its transfer roller
Implementation Method 2
If the transfer roller is an ion-conductive transfer roller, continued application of the above transfer bias from the transfer bias applying section will cause ionic polarization inside the transfer roller to impair the electric conduction
Data Source
AI summary
An image forming apparatus includes a photosensitive drum, a charging section, an exposure section, a developing section, an ion-conductive transfer roller, a transfer bias applying section configured to apply a transfer bias of reverse polarity to charge of toner to the transfer roller, a conveyance section, and a control section. The control section is configured to, during double-sided printing, cause the transfer bias applying section to apply a reverse bias of the same polarity as the charge of the toner to the transfer roller while a recording medium is reversed and conveyed again to a toner image transfer position.