Image Reading Apparatus Roller Force Distribution for Small Sheets
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Solution Overview
Problem
In image reading apparatuses, small size sheets often experience insufficient conveying force, leading to reduced conveying speed and image expansion issues due to the conventional arrangement of rollers, which applies less force to smaller sheets compared to normal size sheets.
Innovation Solution
The apparatus is designed with at least three driving rollers and three driven rollers arranged at central and side portions, where the conveying force applied by the central rollers is greater than those at the side portions, ensuring adequate force for small size sheets, and the use of spring shafts to enhance the elastic force and reduce the size and complexity of the mechanical structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three rollers are arranged in a spaced manner in the sheet-width direction, then normal size sheets can be conveyed properly, but small size sheets receive insufficient conveying force
Solution Approach 1:
The patent applies local quality by differentiating the conveying force characteristics of different rollers. Specifically, the central roller (first roller) is designed to provide stronger conveying force than the side rollers (second and third rollers). This is achieved through structural differences in the roller assembly, where the central roller has a larger diameter or different rotational characteristics, allowing it to deliver enhanced force specifically to small size sheets that contact only this roller, while normal size sheets continue to receive distributed force from all three rollers.
2Force
If small size sheets contact only one roller, then the conveying force is reduced, but increasing the force on that one roller may affect normal size sheet conveyance
Solution Approach 1:
The patent implements local quality by creating a non-uniform roller configuration where the central roller is specifically optimized for small size sheets. The central roller has different structural parameters (such as larger diameter or different surface properties) compared to the side rollers, enabling it to provide concentrated conveying force exactly where needed for small sheets without disrupting the distributed force pattern that normal size sheets experience from all three rollers working together.
3Manufacturing precision
If the conveying force on small size sheets is increased, then image expansion is prevented, but the device complexity increases
Solution Approach 1:
The patent resolves the complexity issue through local quality by modifying only the central roller's characteristics rather than redesigning the entire three-roller system. The side rollers maintain their original configuration, while the central roller is given enhanced properties (such as larger diameter or different rotational inertia) that automatically provide the needed force enhancement for small sheets. This localized modification achieves improved image reading precision for small sheets without requiring complex control systems or multiple adjustable components.
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 configuration ensures that small size sheets are conveyed at an appropriate speed, preventing image expansion and reducing the size and complexity of the apparatus by optimizing the conveying force distribution.
Implementation Method 1
at least three driven rollers configured to be urged by the driving rollers and driven to rotate by rotation of the driving rollers
Data Source
AI summary
An image reading apparatus has a separation section configured to supply a sheet one by one, at least three driving rollers arranged downstream of the separation section in a sheet conveying direction and configured to convey the sheet, at least three driven rollers configured to be urged by the driving rollers and driven to rotate by rotation of the driving rollers, respectively, and an image reader unit configured to read an image of the sheet conveyed in the conveying direction. Sheet conveying forces by one of at least three driven rollers and one of at least three driving rollers arranged at the central portions in the sheet width direction is greater than sheet conveying forces by others of the at least three driven rollers and others of the at least three driving rollers arranged at both side portions in the sheet width direction.