Double-Sided Image Forming Apparatus Sheet Jam Handling
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Solution Overview
Problem
Image forming apparatuses face productivity issues and sheet fouling when a sheet jam occurs during double-sided image formation, leading to wasted sheets and defective products due to the inability to efficiently clean the secondary transfer unit.
Innovation Solution
An image forming apparatus with a controller that synchronizes the timing of toner image formation and sheet feeding, includes a re-feeder to re-transfer images on the second side, and uses a cleaning mechanism to prevent fouling on the back side, maintaining productivity without expensive cleaning mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If toner image formation is started before sheet feeding to improve productivity, then productivity is improved, but sheet jam occurs more frequently causing fouling on the back side
Solution Approach 1:
The system performs preliminary toner image formation on the photosensitive drum before the sheet is fed, allowing the image formation process to be ahead of the sheet conveyance. This preliminary action enables continuous operation without waiting for sheet feeding, thereby improving productivity while maintaining the ability to handle jams through the storage and conditional transfer mechanisms
Solution Approach 2:
The system segments the toner image formation process into multiple stages: formation on the photosensitive drum, temporary storage in the intermediate transfer belt, and conditional transfer to the secondary transfer unit. This segmentation allows the system to decouple image formation from sheet feeding, enabling preliminary formation while providing buffer capacity to handle sheet jam occurrences without fouling
2Manufacturing precision
If sheet feeding is synchronized with toner image formation, then fouling on the back side is prevented, but productivity decreases
Solution Approach 1:
The system performs preliminary toner image formation on the photosensitive drum before the sheet is fed, allowing the image formation process to be ahead of the sheet conveyance. This preliminary action enables continuous operation without waiting for sheet feeding, thereby improving productivity while maintaining the ability to handle jams through the storage and conditional transfer mechanisms
Solution Approach 2:
The controller monitors sheet feeding status and toner image formation progress in real-time, dynamically adjusting the timing and coordination between these processes. This feedback mechanism ensures that toner images are transferred to sheets at the optimal moment, preventing fouling on the back side while maintaining high productivity through efficient resource utilization
3Manufacturing precision
If expensive cleaning mechanism is added to prevent fouling on the back side, then fouling is prevented, but device complexity and cost increase
Solution Approach 1:
The system extracts and transfers the toner image from the intermediate transfer belt to the secondary transfer unit only when necessary (upon detecting sheet jams), rather than continuously cleaning the secondary transfer unit. This selective transfer approach removes the problematic toner before it can cause fouling, eliminating the need for expensive continuous cleaning mechanisms while maintaining image quality
Solution Approach 2:
The system uses the intermediate transfer belt as a temporary, disposable storage medium for toner images. When a sheet jam occurs, the toner image is discarded from the intermediate belt rather than attempting to clean the secondary transfer unit. This approach uses a low-cost, easily replaceable component (the intermediate belt) to protect the more critical secondary transfer unit from fouling
Data Source
AI summary
After outputting a first start signal for causing an image forming unit to start formation of an image for a first side of an i-th sheet, a controller causes a feeding member to start feeding of the i-th sheet, and determines whether or not the i-th sheet has already been detected by a detector. In a case where the i-th sheet has been detected before a predetermined time has elapsed, the controller outputs a second start signal for causing the image forming unit to start formation of an image for second side of an (i−1)th sheet. In a case where the i-th sheet has not been detected before the predetermined time has elapsed, the controller outputs the second start signal after the i-th sheet is detected.