Image Forming Device Back-Face Printing Toner Adhesion Prevention
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Solution Overview
Problem
In image forming devices capable of both-side printing, toner adheres to separation rollers during back-face printing, leading to deteriorated separation efficiency and potential duplicate paper carrying.
Innovation Solution
The device incorporates a moving mechanism that separates the paper supply and separation rollers during back-face printing, preventing toner adherence by maintaining a distance between them, and uses a re-carrying unit with rollers of different materials to minimize toner transfer, ensuring effective separation and preventing duplicate paper carrying.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the paper supply roller and separation rollers are used for both top-face printing and back-face printing, then the device complexity is reduced, but toner adheres to the separation rollers during back-face printing causing duplicate paper carrying
Solution Approach 1:
The paper supply roller is made movable between a first position (contacting the sheet-like medium for top-face printing) and a second position (separated from the sheet-like medium for back-face printing). This dynamic repositioning allows the same roller to serve dual purposes while preventing toner adhesion issues during back-face printing.
Solution Approach 2:
The printing process is segmented into distinct phases with the paper supply roller positioned differently for each phase. During top-face printing, the roller contacts the medium; during back-face printing, it is retracted. This temporal and spatial segmentation prevents harmful toner transfer while maintaining structural simplicity.
2Reliability
If the separation rollers maintain constant contact with the sheet-like medium, then the separation efficiency is improved, but toner from the top face adheres to the rollers during back-face printing
Solution Approach 1:
The separation rollers are configured to move between a first state (contacting each other for separating sheets during top-face printing) and a second state (separated from each other during back-face printing). This dynamic adjustment eliminates the harmful ton adhesion effect while preserving separation efficiency when needed.
Solution Approach 2:
Before back-face printing begins, the separation rollers are retracted to a second state that prevents contact with the printed surface. This preliminary anti-action stops toner adhesion before it can occur, maintaining separation efficiency for the subsequent top-face printing cycle.
3Productivity
If the paper supply roller contacts the sheet-like medium during back-face printing, then the productivity is improved, but duplicate paper carrying occurs due to toner adhesion on the rollers
Solution Approach 1:
The paper supply roller dynamically switches between contacting and not contacting the sheet-like medium based on the printing phase. During back-face printing, it is retracted to prevent toner adhesion that would cause duplicate carrying, while still allowing the re-carrying mechanism to maintain high productivity through continuous operation.
Solution Approach 2:
The re-carrying mechanism acts as an intermediary that carries the sheet-like medium past the image formation unit during back-face printing without requiring the paper supply roller to contact the printed surface, thus preventing duplicate carrying while maintaining productivity.
Data Source
AI summary
An image forming device, comprising: a sheet-like medium accommodation unit; a supply member that carries a sheet-like medium; a pair of separation members that separate the sheet-like medium one by one; an image formation unit; a carrying path; a re-carrying unit to move inversely the sheet-like medium whose top face has been subjected to printing; a moving mechanism to move the supply member close to or away from the sheet-like medium and to move the pair of separation members close to or away from each other so that a path for the inversely carried sheet-like medium is formed; and a control unit to control the moving mechanism such that, when back-face printing is performed, the supply member is in a state of being moved away from the sheet-like medium and the pair of separation members are in a state of being moved away from each other.