Re-conveying Guide for Image Formers
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Solution Overview
Problem
Image forming apparatuses face issues with paper folds and jams due to sheets deviating in width direction or curling during double-sided printing, as existing side registration guides are ineffective in maintaining sheet alignment.
Innovation Solution
The apparatus incorporates a re-conveying device with a guide that changes the sheet's conveying direction from vertical to horizontal, featuring a first guide surface with a planar area for consistent contact angle and a second guide surface positioned closer to the curvature center, reducing the likelihood of sheet folding and jamming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional side registration guide with inclined side wall is used, then the sheet position in width direction is guided, but paper folds and paper jams occur when the sheet deviates or is curled
Solution Approach 1:
The guide surface is segmented into multiple functional areas: a first guide surface area for initial contact and direction change, a second guide surface area for maintaining guidance, and a third guide surface area for final positioning. This segmentation allows each area to perform its specific function optimally, preventing paper folds and jams by distributing the guidance function across multiple zones rather than relying on a single inclined wall
Solution Approach 2:
The guide surface is designed with varying inclination angles in different areas. The first guide surface area has a first inclination angle for initial direction change, the second area has a second inclination angle for maintaining guidance, and the third area has a third inclination angle for final positioning. This dynamic variation in inclination angles adapts to the sheet's state during conveying, effectively handling deviated or curled sheets without causing folds or jams
2Ease of operation
If the guide surface is made inclined to change conveying direction, then the sheet is guided in width direction, but the contact angle varies causing sheet deviation
Solution Approach 1:
Different areas of the guide surface are given different local qualities in terms of inclination angle. The first guide surface area has a specific inclination for initial contact, the second area has a different inclination for maintaining guidance, and the third area has yet another inclination for final positioning. This local quality variation ensures that each area performs its specific guidance function with optimal precision, maintaining consistent contact angles where needed while providing direction changes where required
Data Source
AI summary
An image forming apparatus includes an image forming device, a switchback roller, and a re-conveying device. The re-conveying device includes a guide configured to change a conveying direction of a sheet conveyed by the switchback roller from a vertical direction to a horizontal direction and to guide the sheet in a width direction. The guide has a first guide surface and a second guide surface. The first guide surface and the second guide surface define a conveying path therebetween. The second guide surface is located closer to a center of a curvature of the conveying path than the first guide surface in a radial direction of the curvature. The first guide surface has a first area being planar and a second area downstream of the first area. The first area is configured to be contacted by a leading end of the sheet.