Image Forming Apparatus Web Residual Quantity Detection
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Solution Overview
Problem
In image forming apparatuses, it is challenging to accurately detect the residual quantity of a cleaning web after power cycles, leading to potential web exhaustion and image defects, as existing methods struggle to determine the web's remaining length accurately after maintenance operations.
Innovation Solution
The apparatus includes a detection unit to measure the outer diameter of the web wound around a roller and a control unit that assesses the difference in web diameter before and after power cycles, allowing or preventing image formation based on predetermined thresholds to ensure the web is not excessively used.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the web residual quantity is detected using a notched portion and flag member with photosensor, then the web replacement timing can be detected, but the detection accuracy deteriorates when the web is rewound during power-OFF state
Solution Approach 1:
The patent introduces an outer diameter detection unit as an intermediary measurement method. Instead of directly detecting web length through the notched portion method (which fails after rewind), the system detects the outer diameter of the web-wound roller. This intermediary measurement provides a reliable indicator of web residual quantity that works consistently both before and after power cycles, resolving the detection accuracy issue.
Solution Approach 2:
The patent changes the detection parameter from web length (detected via notched portion position) to outer diameter of the web-wound roller. This parameter change enables continuous and accurate detection of web residual quantity regardless of whether the web has been rewound during power-OFF state, as outer diameter directly correlates with remaining web amount and is not affected by rewind operations.
2Reliability
If the image forming apparatus prevents job execution after web reaches predetermined residual quantity, then web exhaustion is avoided, but productivity decreases due to unnecessary web replacement
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the outer diameter of the web-wound roller and compares it against threshold values. Based on this feedback, the system intelligently determines whether to permit or prevent image forming jobs. This feedback loop allows the system to accurately assess web residual quantity and make appropriate decisions, preventing both web exhaustion and unnecessary job interruptions.
Solution Approach 2:
The patent introduces dynamic control logic that adapts its behavior based on the detected outer diameter changes. The control unit evaluates the magnitude of outer diameter reduction and dynamically decides whether to allow job execution or prevent it. This dynamic approach replaces the static prevention mechanism, enabling the system to maintain productivity while ensuring web exhaustion prevention through intelligent, condition-based decision-making.
3Ease of operation
If the web is rewound during maintenance operation, then the web residual quantity is reduced, but the detection system cannot accurately detect the new residual quantity
Solution Approach 1:
The patent replaces the mechanical notched portion detection system with an outer diameter measurement system. The outer diameter detection unit uses non-contact measurement (optical or capacitive sensing) to determine web residual quantity, eliminating the need for physical notches and flag members. This substitution enables accurate detection after rewind operations, as the measurement is based on the current web amount rather than a fixed reference point that becomes invalid after rewind.
Data Source
AI summary
An image forming apparatus includes an image forming unit, a first rotary member, a second rotary member, a web, a feed roller, a winding roller, a contact member, a detection unit, and a control unit. In a state where the apparatus is turned from a first power-ON state to a second power-ON state through a power-OFF state after the contact member reached a notch, if a difference between a diameter of a web at an end of the first power-ON state and the diameter of the web at a start of the second power-ON state is equal to or greater than a predetermined value, the control unit controls the image forming unit not to form a toner image. In the state after the contact member reached the notch, if the difference is smaller than the predetermined value, the control unit permits the image forming unit to form a toner image.