Skew Correction Roller Pair for Sheet Wrinkle Reduction
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Solution Overview
Problem
Existing sheet conveyance devices in image forming apparatuses often form wrinkles in sheets due to waves caused by the interaction of the leading end of the sheet with multiple nip portions of the registration roller pair, which can lead to instability when passing through subsequent bend portions.
Innovation Solution
A sheet conveyance device with a skew correction roller pair and a transfer unit, where the skew correction roller pair forms two nip portions apart in the width direction, and a first and second conveyance guide that bend the sheet to ensure the first surface becomes the inside surface, reducing wrinkles by stabilizing sheet orientation through a specific contact configuration with the registration roller pair and intermediate transfer belt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a leading end of a sheet comes into contact with nip portions of a registration pair being stopped, then skew correction is achieved, but waves occur in the sheet between the plurality of nip portions in a width direction
Solution Approach 1:
The registration roller pair is divided into multiple nip portions (first nip portion and second nip portion) disposed apart from each other in the width direction. This segmentation allows the leading end of the sheet to contact multiple nip portions simultaneously, distributing the correction force and reducing wave formation while maintaining effective skew correction.
Solution Approach 2:
The nip portions are arranged in the width direction (lateral dimension) rather than only in the conveyance direction. This spatial arrangement in another dimension enables simultaneous contact of the sheet leading end with multiple nip portions, correcting skew without creating waves along the conveyance path.
2Ease of operation
If the sheet having the wave passes a bend portion disposed downstream from the registration roller pair, then the sheet is guided through the bend, but wrinkles are formed in the sheet
Solution Approach 1:
The sheet is guided to contact the bend inner side guide portion before entering the bend portion. This preliminary positioning ensures the sheet follows the correct path and prevents waves from developing into wrinkles during the bending process.
Solution Approach 2:
The bend inner side guide portion acts as an intermediary element between the registration roller pair and the bend portion. It mediates the sheet's transition by providing a controlled contact surface that directs the sheet smoothly through the bend, preventing wrinkle formation.
3Adaptability or versatility
If a registration roller pair that has a plurality of nip portions disposed apart from each other in the sheet width direction is used, then skew correction capability is improved, but wave occurrence between nip portions increases
Solution Approach 1:
Different regions of the registration roller pair are assigned different functions: the first nip portion primarily contacts the sheet for skew correction, while the second nip portion is positioned to suppress wave formation. This local differentiation of functionality allows the system to achieve both skew correction and wave suppression simultaneously.
Data Source
AI summary
A sheet conveyance device includes a conveyance roller pair. A skew correction roller pair conveys the sheet after contacting two nip portions, and a sheet skew is corrected in a state in which the skew correction roller pair is being stopped. The sheet having a toner image is bent by a first conveyance guide such that a sheet first surface becomes an inside surface. The sheet is bent by the first and second conveyance guides to cause the sheet first surface to be the inside surface and a sheet second surface to be an outside surface. The skew correction roller pair includes two first rotary members of a first roller. A second roller and the two first rotary members form the two nip portions. The second roller and the first conveyance guide contact the sheet first surface. The first roller and the second conveyance guide contact the sheet second surface.