Transfer Pressure Control for Belt Positioning in Image Forming Apparatus
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Solution Overview
Problem
In image forming apparatuses with belt-like intermediate transfer systems, maintaining uniform transfer pressure across the width direction is challenging due to non-uniform belt tension changes during steering operations, leading to toner concentration differences in the transferred images.
Innovation Solution
The apparatus incorporates a transfer pressure adjusting mechanism that controls the movement of a transfer roller based on the adjustment state of a steering roller, ensuring uniform pressure distribution across the belt width by adjusting the pressing force of the transfer roller, thereby maintaining toner concentration uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If steering operation is performed to adjust belt position, then the belt is located in appropriate position with respect to the photoreceptor, but the tension becomes non-uniform between proximal side and distal side in width direction
Solution Approach 1:
The patent changes the pressing force parameter of the transfer roller based on the steering roller adjustment state. When the steering roller is adjusted to correct belt position, the transfer pressure adjusting mechanism modifies the pressing force to compensate for the resulting non-uniform tension, thereby maintaining uniform transfer pressure across the belt width.
2Productivity
If transfer roller presses belt toward photoreceptor to form transfer nip, then toner image is transferred, but non-uniform pressure causes toner concentration difference in width direction
Solution Approach 1:
The system implements feedback control where the controller detects the steering roller adjustment state and automatically adjusts the pressing force of the transfer roller accordingly. This closed-loop control ensures that transfer pressure remains uniform across the belt width even when belt tension varies due to steering operations, preventing toner concentration differences.
3Force
If spring presses primary transfer roller toward image carrier, then transfer pressure is applied, but pressure drops at center of belt in width direction
Solution Approach 1:
The patent applies local quality by making the pressing force adjustable at different locations. The transfer pressure adjusting mechanism selectively increases pressing force at the center of the belt where pressure drops, while maintaining appropriate pressure at other regions, thereby achieving uniform pressure distribution across the entire belt width.
Data Source
AI summary
An image forming apparatus has an image forming section having a photoreceptor on which a toner image is formed, an endless belt that revolves with its outer surface facing the photoreceptor, a steering roller adapted to provide a tension to the belt and adjust the position of the belt in the width direction, a transfer roller that presses the belt toward the photoreceptor so as to form a transfer nip where the toner image is transferred, a transfer pressure adjusting mechanism adapted to adjust pressing force when the transfer roller presses the belt toward the photoreceptor, and a controller adapted to control the pressing force adjusted by the transfer pressure adjusting mechanism, according to the adjustment state of the steering roller.