Sheet Conveyance Skew Correction via Offset Nip Line
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Solution Overview
Problem
Existing sheet conveying apparatuses struggle to accurately correct skew feeding, especially for thin sheets with low stiffness, as they often result in buckling, misalignment, and damage due to the design of reference guides and rollers, which leads to reduced image quality and increased jamming.
Innovation Solution
A sheet conveying apparatus with a skew correction portion featuring a reference guide and obliquely feeding rollers, where the positional relation of the rollers is offset to prevent the sheet edge from being caught in the joint between guide members, ensuring sliding contact with the skew correction reference surface and guiding the sheet to avoid damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gap between upper guide and lower guide is made small to prevent sheet buckling, then sheet stability is improved, but conveyance resistance increases
Solution Approach 1:
The patent applies the dynamics principle by making the gap between the upper guide and lower guide adjustable rather than fixed. The gap width is dynamically changed based on sheet thickness: smaller gaps for thin sheets to prevent buckling, and larger gaps for thick sheets to reduce conveyance resistance. This is achieved through a movable guide mechanism that can be positioned at different locations along the guide member, allowing the system to adapt to different sheet conditions optimally.
2Manufacturing precision
If the abutting reference guide portion is formed with a U-shaped cross section to guide sheet edges, then sheet alignment is improved, but thin sheets may be caught in the joint and damaged
Solution Approach 1:
The patent applies the dynamics principle by making the guide member movable rather than fixed. The guide member can be positioned at different locations along the abutting reference guide portion, allowing the system to adapt to different sheet conditions. For thin sheets, the guide member can be positioned to avoid creating sharp corners where sheets might be caught, while still providing adequate alignment guidance.
Solution Approach 2:
The patent applies the local quality principle by differentiating the function of different parts of the guide system. The abutting reference guide portion provides alignment guidance, while the movable guide member provides localized support that can be adjusted based on sheet thickness. This localized adjustment allows the system to provide necessary guidance without creating harmful sharp corners that could damage thin sheets.
3Manufacturing precision
If skew correction is performed by detecting skew feeding and inclining the image, then image position accuracy is improved, but processing time increases and productivity decreases
Solution Approach 1:
The patent applies the preliminary action principle by performing skew correction at the sheet conveyance stage rather than at the image formation stage. The movable guide member corrects sheet skew before the sheet reaches the image forming portion, eliminating the need for subsequent image inclination calculations and processing. This preliminary mechanical correction maintains image position accuracy while avoiding the time-consuming computational processes that would reduce productivity.
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
This solution effectively prevents damage to thin sheets by ensuring smooth conveyance and accurate skew correction, enhancing image position accuracy and reducing the likelihood of jams, thereby improving productivity and image quality.
Implementation Method 1
a side edge of a sheet comes in sliding contact with the skew correction reference surface
Data Source
AI summary
A sheet conveying apparatus and an image forming apparatus are provided.An upper guide opposed to a lower guide is structured as another member, and a positional relation is set such that a nip line of a pair of obliquely feeding is offset toward the lower guide with respect to a center line of a gap portion between the upper and lower guides. Accordingly, a sheet being conveyed is once guided by an inclined face of the lower guide to the upper guide, and is then caused to abut the abutting reference surface while being in sliding contact with the upper guide member. Therefore, a disadvantage that a side edge of the sheet is caught in a joint can be prevented.