Image Forming Apparatus Backward Sheet Movement Prevention
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Solution Overview
Problem
Conventional image forming apparatuses using triple rollers face issues with sheets moving backward during reversal operations, leading to conveyance failures and interference with subsequent sheets, as there is no effective mechanism to prevent backward movement near the triple rollers.
Innovation Solution
An image forming apparatus with a movable regulation portion that switches between allowing and blocking positions to prevent sheets from entering the nip portion between the first and second rollers during reverse rotation, ensuring sheets are not conveyed backward, utilizing a flipper and backward movement prevention portion to control the regulation position in conjunction with the rotational direction of the driving rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If triple rollers are used to perform discharge and reversal operations, then the apparatus structure is simplified, but sheets may move backward during reversal operations causing conveyance failure
Solution Approach 1:
A regulation member is introduced as an intermediary component between the discharge tray and the triple rollers. This regulation member protrudes into the discharge tray area to prevent sheets from moving backward during reversal operations, while not interfering with normal discharge operations. The regulation member acts as a mediator that resolves the conflict between simplified structure and reliable conveyance.
2Device complexity
If the regulation member is located much below the nip portion between the discharge roller pair, then the structure is simpler, but the effect cannot be attained when sheets contact the discharge roller pair
Solution Approach 1:
The regulation member is positioned to protrude horizontally into the discharge tray area, creating a regulatory zone in the horizontal dimension rather than relying solely on vertical positioning below the nip portion. This dimensional approach ensures that sheets attempting to move backward are blocked by the regulation member before they can contact the discharge roller pair, effectively preventing backward movement while maintaining structural simplicity.
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
Prevents conveyance failures by blocking the backward movement of sheets during reversal operations, allowing for efficient two-sided printing without sheet interference, enhancing operational reliability and speed.
Implementation Method 1
a sheet on which printing has been completed on a first side is switched back by a reverse roller pair, fed again to a two-sided printing conveyance path
Data Source
AI summary
An image forming apparatus includes an image forming unit configured to form an image on a sheet, a stacking portion on which the sheet having the image formed thereon is to be stacked, a first roller capable of forward and reverse rotations, a second roller capable of rotating with the first roller when the first roller makes a forward rotation, a third roller capable of rotating with the first roller when the first roller makes a reverse rotation and then the forward rotation, a regulation portion movable between a regulation position where entering of the sheet into a nip portion between the first and second rollers is prevented, and an allowing position where discharge of the sheet is allowed, and a movement unit configured to cause the regulation portion to be placed in the allowing position during forward rotation, and to be placed in the regulation position during reverse rotation.