Sheet Conveying Roller Step Structure for Skew and Sagging Control
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face issues with misalignment and sagging of rollers, leading to creases in sheets and inefficient conveyance, particularly at the registration rollers where the pressure distribution is uneven.
Innovation Solution
A sheet conveying device with a pressing portion that includes a pressing member and urging member to uniformly press the first roller towards the second roller, featuring a step portion on the first roller with a smaller diameter than the contact region, enhancing the pressure distribution and reducing misalignment and sagging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressing portion is added to press the first roller toward the second roller, then roller alignment and sheet conveyance performance are improved, but device complexity increases
Solution Approach 1:
The pressing portion utilizes the weight of the first roller itself as the pressing force. The first roller is supported by a support portion that allows it to rotate, and its own weight provides the necessary pressure against the second roller, eliminating the need for separate pressing mechanisms while maintaining reliable roller alignment
Solution Approach 2:
A support portion is introduced as an intermediary element between the first roller and the second roller. This support portion serves as a mediator that transmits the weight of the first roller to provide consistent pressing force, while also serving as a mounting point for the conveying mechanism
2Force
If the outer diameter of the first roller is increased to match the contact region diameter, then pressing force is improved, but the risk of crease formation increases
Solution Approach 1:
The first roller is designed with non-uniform diameter characteristics - a smaller outer diameter at the conveying surface and a larger diameter at the pressing contact region. This local quality variation allows the roller to exert sufficient pressing force at the contact point while maintaining a smaller overall diameter that prevents crease formation in the sheet during conveyance
3Stability of the object's composition
If uniform pressing force is applied across the entire roller surface, then roller contact is improved, but sheet deformation and creases increase
Solution Approach 1:
The pressing force is concentrated at a specific pressing portion rather than being uniformly distributed across the entire roller surface. This localized pressing approach provides stable roller contact at the critical interface while avoiding excessive pressure that would cause sheet deformation or crease formation in other areas
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
The solution effectively suppresses misalignment and sagging of rollers, improves sheet conveyance performance, and corrects skewed conveyance, ensuring smooth and efficient sheet handling.
Implementation Method 1
a pressing urging member that urges the pressing member toward the second roller
Implementation Method 2
The first roller has a step portion that is formed in an outer circumferential part of it all over its circumference. The step portion has an outer diameter smaller than the outer diameter of a contact region with the second roller, and is contacted by the pressing member.
Data Source
AI summary
A sheet conveying device includes a first roller, a second roller, and a pressing portion. The pressing portion includes a pressing member contacting the first roller from its side opposite from the second roller and a pressing urging member urging the pressing member toward the second roller. The first roller has a step portion formed in an outer circumferential part of it all over its circumference. The step portion has an outer diameter smaller than the outer diameter of a contact region with the second roller and is contacted by the pressing member.