Image Forming Apparatus Transfer Control for AC Banding Suppression
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Solution Overview
Problem
In image forming apparatuses using the electrophotographic method, the overlap of currents from the commercial power source to the heating member and transfer member can cause AC banding, leading to uneven transfer properties and image defects in the subscanning direction.
Innovation Solution
An image forming apparatus with a current detecting portion connected between the image bearing member and ground potential, and a control portion that adjusts the transfer power source output based on detected current or voltage, to manage the current flow during toner transfer and heating processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heating member is heated by applying AC voltage from commercial power source, then the recording material can be heated to fix toner image, but current overlap between heating member and transfer member causes AC banding and image unevenness
Solution Approach 1:
The patent employs feedback control by detecting the current flowing through the transfer member and using this information to control the transfer power source. The control portion adjusts the transfer voltage based on the detected current to suppress AC banding caused by current overlap between the heating member and transfer member, thereby maintaining uniform transfer quality while the heating member operates at elevated temperatures.
Solution Approach 2:
The patent changes the electrical parameters (voltage and current) of the transfer power source based on detected conditions. By dynamically adjusting the transfer voltage according to the detected current flow, the system optimizes transfer uniformity and suppresses AC banding artifacts that would otherwise occur during simultaneous heating and transfer operations.
2Manufacturing precision
If current detecting means detects current flowing through transfer member, then AC banding can be suppressed, but the configuration only works effectively when transfer member impedance is low
Solution Approach 1:
The patent uses feedback control where the detected current from the transfer member is fed back to the control portion, which then adjusts the transfer power source output. This closed-loop system adapts to different impedance conditions by continuously monitoring current flow and making real-time adjustments, extending effectiveness beyond fixed low-impedance scenarios.
Solution Approach 2:
The patent implements dynamic control of the transfer power source based on real-time current detection. The system transitions from static voltage application to dynamic voltage adjustment, where the transfer voltage is continuously modified according to detected current conditions, enabling effective AC banding suppression across varying impedance conditions.
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
The solution effectively suppresses AC banding by controlling the transfer power source to maintain current within an appropriate range, thereby reducing image defects and ensuring consistent toner transfer quality.
Implementation Method 1
a heating source for heating the recording material nipped by the fixing portion and a heating member in contact with the recording material in the fixing portion and the heating source heating the recording material through the heating member by heating by the voltage being applied from an AC power source
Implementation Method 2
a transfer member configured to form a transfer portion in contact with the image bearing member and to transfer the toner image to a recording material from the image bearing member in the transfer portion
Data Source
AI summary
An image forming apparatus includes an image bearing member, a developing device, a transfer member, a transfer power source and a fixing device. The fixing device is provided with a heating source and a heating member in contact with a recording material in a fixing portion and the heating source heats the recording material through the heating member by heating by the voltage being applied from an AC power source. A detector connected between the image bearing member and a ground potential without interposing the transfer member detects a current or a voltage. A controller controls the current outputting from the transfer power source based on a detecting result of the detecting portion while the toner image is transferred to the recording material from the image bearing member in the transfer portion and the recording material is heated in the fixing portion.