Convex Guide Part for Wrinkle-Free Sheet Conveyance
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Solution Overview
Problem
Image forming apparatuses face challenges in conveying thin sheets without causing wrinkles due to the stiffness of the sheets, which requires a longer conveying path and larger apparatus size to accommodate curved paths for guide members, leading to inefficiencies in sheet alignment and image formation.
Innovation Solution
The apparatus incorporates a main conveying path with a conveying roller pair, a joining section featuring a convex guide part and planar guide parts, and a sheet member to guide sheets from upper and lower feeding paths, ensuring proper alignment and reducing wrinkles by stretching the sheet in the width direction through a narrower gap between the convex guide and sheet member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a guide member is disposed such that the front edge of the sheet abuts against the guide member, then the sheet can be deflected corresponding to its thickness, but the conveying path must be formed into a curved path which increases the length of the conveying path and the size of the image forming apparatus
Solution Approach 1:
The guide member is designed with a convex portion that protrudes in the width direction of the sheet, utilizing the lateral dimension to achieve sheet deflection and alignment without requiring an extended conveying path length. This dimensional approach allows the guide member to effectively guide sheets of different thicknesses while maintaining a compact apparatus size.
2Ease of operation
If the conveying path is formed into a curved path to accommodate the guide member, then the sheet can be properly guided, but the size of the image forming apparatus becomes large
Solution Approach 1:
Instead of extending the conveying path in the longitudinal direction with a curved path, the guide member utilizes the width direction by protruding in the lateral dimension. This allows the sheet to be guided and deflected appropriately without increasing the apparatus volume, as the guiding function is achieved through lateral protrusion rather than longitudinal curvature.
3Adaptability or versatility
If a thin sheet is stored in a lower sheet feeding cartridge, then sheet diversity is accommodated, but wrinkles are caused by waving of the sheet at the skew collecting because the thin sheet is not stiff
Solution Approach 1:
The guide member performs preliminary deflection and alignment of the sheet before it reaches the skew collecting section. By pre-deflecting the sheet in the width direction through the convex portion, the sheet is properly positioned and stabilized, preventing wrinkles from forming during subsequent conveyance through the resist roller pair.
Solution Approach 2:
The guide member acts as an intermediary element between the sheet feeding cartridge and the resist roller pair. It provides a transition zone where sheets of different thicknesses can be uniformly deflected and aligned, serving as a mediator that prevents direct contact between the flexible thin sheet and the rigid skew collecting mechanism, thereby preventing wrinkle formation.
Data Source
AI summary
An image forming apparatus includes a conveying guide and a sheet member. The conveying guide is provided in a joining section and guides a sheet to a conveying roller pair along a main conveying path. The sheet member is provided in the joining section and configured to form a lower conveying path with the conveying guide and to guide the sheet from an upper conveying path toward the main conveying path. The conveying guide has a convex guide part and planer guide parts. The convex guide is provided at a center portion and projects toward the sheet member. The planer guide parts are provided on both sides of the convex guide part. A first gap formed between the convex guide part and the sheet member is narrower than a second gap formed between the planer guide part and the sheet member.