Sheet Discharge Device with Adjustable Nip Pressure Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sheet discharge devices with decurl units face challenges in maintaining appropriate discharge angles and preventing paper jams due to varying sheet curvatures, leading to compromised sheet stacking properties.
Innovation Solution
A sheet discharge device with a discharge roller, two pinch rollers, and an adjustment unit that changes the pressure ratio between the nip portions formed by the rollers to adapt to different sheet curvatures, ensuring balanced pressure application and stable discharge angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the holder is moved to adjust decurl force for small curvature sheets, then the decurl force is lowered appropriately, but the discharge angle becomes smaller causing sheet stacking failure
Solution Approach 1:
The patent divides the pressure application into two independent nip portions (first nip portion between discharge roller and first pinch roller, second nip portion between discharge roller and second pinch roller) with independently adjustable pressures. This segmentation allows the pressure ratio between the two nips to be adjusted according to sheet curvature while keeping the discharge angle stable, resolving the contradiction between adaptability and reliability.
Solution Approach 2:
The patent introduces dynamic adjustability of the pressure ratio between the two nip portions while maintaining fixed positional relationships of the rollers. The urging unit can dynamically change the pressure distribution according to sheet curvature without moving the rotation centers, thus adapting to different conditions while preserving stable discharge angle and reliable sheet stacking.
2Adaptability or versatility
If the downstream side pinch roller moves to the upstream side when holder is moved, then decurl force is adjusted, but the discharge angle becomes smaller leading to sheet stacking failure
Solution Approach 1:
The patent segments the pressure adjustment function into two independent nip portions with separate pinch rollers. Each pinch roller can be independently pressured against the discharge roller, allowing decurl force adjustment through pressure ratio change rather than positional movement, thus maintaining stable discharge angle while achieving adaptability.
Solution Approach 2:
The patent changes the pressure parameter (force) rather than the positional parameter when adjusting for different sheet curvatures. The urging unit adjusts the pressure ratio between the first and second nip portions, keeping the rotation centers of all rollers fixed. This parameter change approach maintains stable discharge angle while providing the needed adaptability.
3Device complexity
If constant decurl force is applied with two pinch rollers, then the structure is simple, but sheets with small curvature may curl in inverse direction
Solution Approach 1:
The patent introduces dynamic pressure adjustment capability into the decurl unit while maintaining a relatively simple structure. The urging unit enables the pressure ratio between the two nip portions to be adjusted according to sheet curvature, allowing the same basic structure to adapt to different conditions and prevent inverse curling while correcting various curvature types effectively.
Data Source
AI summary
A sheet discharge device includes a discharge roller, a first roller configured to form a first nip portion by contacting the discharge roller, a second roller configured to form a second nip portion by contacting the discharge roller on a downstream side of the first roller in a rotation direction of the discharge roller, an urging unit configured to urge the first roller and the second roller toward the discharge roller, and an adjustment unit configured to adjust a ratio of a pressure of the second nip portion to a pressure of the first nip portion in a state in which the first roller and the second roller are kept in contact with the discharge roller by the urging unit, wherein a sheet is conveyed while being simultaneously held by the first nip portion and the second nip portion.