Conveyor Nip Roll Asymmetry for Sheet Skew Correction
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Solution Overview
Problem
Conventional image forming apparatuses face difficulties in preventing sheet skew during switchback operations, leading to oblique feeding issues, which existing improvements have not adequately addressed.
Innovation Solution
A conveyor system comprising a first conveying unit with stronger nip roll sets and a second conveying unit with weaker nip roll sets, positioned closer to the center of the sheet, to correct sheet alignment and prevent skewing during switchback operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a switchback system is used to convey sheets in image forming apparatus, then productivity is improved by enabling two-side printing, but sheet skew occurs during switchback operations
Solution Approach 1:
The conveyor system is divided into multiple independent conveying units, each with its own nip roll sets. The first conveying unit has first nip roll sets positioned at outer locations, while the second conveying unit has second nip roll sets positioned at inner locations. This segmentation allows differential control of nip forces at different positions and stages of sheet conveyance, enabling precise correction of sheet skew during switchback operations while maintaining high productivity through automated two-side printing
Solution Approach 2:
Different nip roll sets are configured with different nip strengths tailored to specific conveying stages. The first nip roll sets in the first conveying unit apply stronger nip forces at outer locations to initially guide the sheet, while the second nip roll sets in the second conveying unit apply weaker nip forces at inner locations for fine adjustment during switchback. This local differentiation of nip characteristics enables precise control of sheet alignment throughout the conveyance process
2Ease of operation
If conventional switchback conveyance is used, then sheet conveyance is achieved, but oblique feed of the sheet occurs after switchback operation
Solution Approach 1:
The first nip roll sets are positioned at outer locations of the sheet and configured to apply stronger nip forces before the sheet reaches the switchback point. This preliminary action at the outer edges creates a corrective moment that prevents oblique feed from occurring in the first place, rather than attempting to correct skew after it develops during the switchback operation
Solution Approach 2:
The nip roll sets are asymmetrically positioned relative to the sheet - first nip roll sets at outer locations and second nip roll sets at inner locations. This asymmetric arrangement creates different leverage points and nip force distributions that generate corrective moments to counteract the oblique feed tendency inherent in switchback conveyance, improving sheet feed accuracy
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 described conveyor system effectively reduces sheet skew by applying differential nip forces, ensuring accurate and efficient sheet conveyance during switchback operations, enhancing printing productivity.
Implementation Method 1
a first conveying unit including a pair of first nip roll sets configured to nip and convey the sheet, and a second conveying unit including a second nip roll set configured to nip and convey the sheet from the first conveying unit
Data Source
AI summary
A conveyor has a first conveying unit including a pair of first nip roll sets configured to nip and convey the sheet, and a second conveying unit including a second nip roll set configured to nip and convey the sheet from the first conveying unit. The second nip roll set nips the sheet at an inner location than the first nip roll set, and the first nip roll set nips the sheet more strongly than the second nip roll set.