Sheet Discharging Roller Switchback Guide for Jamming
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Solution Overview
Problem
In double-sided image forming processes, sheets often hang down and get oriented towards the main conveying passage during switch-back conveyance, leading to jamming issues as they reverse back to the image forming section.
Innovation Solution
An image forming apparatus with a sheet-discharging roller capable of rotating in both normal and reverse directions, assisted by a controller and an assisting mechanism that adjusts the sheet's posture, ensuring smooth switch-back conveyance by guiding the sheet into the reversing conveying passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet-discharging rollers perform reverse rotation for switch-back conveyance, then the sheet is transported back to the image forming section for double-sided printing, but the leading end of the sheet hangs down and orients toward the main conveying passage instead of the reversing conveying passage, causing jamming
Solution Approach 1:
A guide member is introduced as an intermediary element between the sheet-discharging rollers and the conveying passages. This guide member actively directs the leading end of the sheet during reverse rotation, ensuring it enters the reversing conveying passage correctly rather than hanging down toward the main conveying passage, thus preventing jamming while maintaining double-sided printing functionality
Solution Approach 2:
The sheet-discharging rollers are designed to protrude a predetermined amount of the sheet to outside during reverse rotation before full switch-back occurs. This preliminary action ensures the leading end is properly positioned and controlled at the critical moment of direction change, preventing it from orienting incorrectly toward the main conveying passage
2Adaptability or versatility
If the sheet is conveyed through the switch-back mechanism, then double-sided image forming is enabled, but sheet jamming occurs due to improper orientation during reverse conveyance
Solution Approach 1:
The guide member serves as a mediator that actively shapes the sheet's path during switch-back conveyance. By physically guiding the leading end, it ensures smooth transition into the reversing conveying passage, eliminating the hanging down problem and enabling reliable double-sided image forming operation
Solution Approach 2:
The system changes the rotational direction parameter of the sheet-discharging rollers from normal forward rotation to reverse rotation at the appropriate timing. This parameter change enables the sheet to be fed back into the conveying system for double-sided printing, while the guide member ensures this parameter change does not cause orientation problems
Data Source
AI summary
An image forming apparatus includes a first sheet conveying passage that conveys a sheet through an image forming section. A sheet-discharging roller is on an outlet side of the first sheet conveying passage and can rotate in opposite directions. A second sheet conveying passage has an inlet connected to the first sheet conveying passage downstream from the image forming section and an outlet connected to the first sheet conveying passage upstream from the image forming section. A controller controls double-sided printing by causing the sheet-discharging roller to rotate forward to advance the sheet outside the sheet-discharging roller, and then to rotate in reverse to execute a switchback for transporting the sheet to the inlet side of the second sheet conveying passage and then to return the sheet to the upstream of the image forming section. An assisting mechanism adjusts a posture of the sheet to assist the switchback.