Image Reading Apparatus Roller Nipping Force Control
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Solution Overview
Problem
Conventional image reading apparatuses experience skewing of sheets due to uneven nipping forces applied by roller pairs attached to different driven shafts, resulting from the use of the same coil springs, which leads to inconsistent conveyance forces.
Innovation Solution
The apparatus employs a configuration where separate driven shafts are inserted into driven rollers, with each shaft being urged against a driving roller, ensuring equal nipping forces across all roller pairs, thus preventing skewing by maintaining consistent conveyance forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same coil springs are employed to press the driven shafts, then the device complexity is reduced, but the nipping force becomes uneven across different roller pairs causing sheet skewing
Solution Approach 1:
The patent applies local quality by making each driven shaft have different pressing forces through asymmetric coil spring configurations. Specifically, the first and second driven shafts are pressed by coil springs with different numbers of turns, creating locally optimized pressing forces for each roller pair to prevent sheet skewing while maintaining overall device functionality.
2Manufacturing precision
If different numbers of coil spring turns are used for different driven shafts, then the nipping force is equalized across roller pairs, but the manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by varying the number of turns of coil springs for different driven shafts. The first driven shaft uses a coil spring with a specific number of turns while the second driven shaft uses a coil spring with a different number of turns, allowing precise control over pressing forces and nipping forces to achieve uniform sheet conveyance without skewing.
3Stability of the object's composition
If driven rollers are attached to separate driven shafts with different pressing forces, then sheet skewing is prevented, but the force control becomes more complex
Solution Approach 1:
The patent applies self-service by using coil springs with different numbers of turns to automatically generate the required different pressing forces for each driven shaft. The mechanical configuration of the coil springs themselves provides the force differentiation without requiring external control mechanisms, sensors, or active adjustment systems, thereby maintaining stability while avoiding complex force control.
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 effectively prevents sheet skewing, allowing for reliable and uniform conveyance of various sheet sizes without corner folding, simplifying the apparatus design and reducing costs.
Implementation Method 1
Each end portion of each driven roller is pressed by a coil spring against the driving roller. Thus, each driven roller is urged against each driving roller.
Data Source
AI summary
An image reading apparatus including an wall disposed on a first side of the image reading apparatus in a width direction orthogonal to a conveyance direction of a sheet is provided. The wall extends in a direction orthogonal to the width direction. The image reading apparatus further includes a first driven roller disposed on a second side in the width direction relative to the wall; a first driving roller opposed to the first driven roller; a first driven shaft inserted into the first driven roller and urged against the first driving roller; a second driven roller disposed on the second side relative to the first driven roller; a second driving roller opposed to the second driven roller; a second driven shaft inserted into the second driven roller and urged against the second driving roller; and a reader unit configured to read the image on the sheet.