Sheet-feeding device with movable second roller for friction control
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Solution Overview
Problem
Conventional sheet-feeding devices using a belt to increase frictional force can result in multiple-feeding of sheets due to increased pressing force, leading to sheet-feeding failures when the sheet-feed roller rotation halts.
Innovation Solution
A sheet-feeding device with a first and second feeding roller, where the second roller is movable between non-feeding and feeding positions, and a controller to adjust its position based on sensor detections to ensure proper sheet feeding and prevent multiple-feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a belt is used to increase the area of contact and frictional force for sheet feeding, then sheet non-feeding is prevented, but pressing force increases causing multiple-feeding of sheets
Solution Approach 1:
The patent employs a movable second feeding roller that can dynamically change its position between a retracted state (not contacting the sheet) and a contact state (touching the sheet). This dynamic adjustment allows the system to optimize the contact area: when the first roller slips, the second roller moves into contact to provide additional friction without continuously applying excessive pressing force that would cause multiple sheets to feed
2Reliability
If the area of contact between sheet-feed roller and sheet is increased to increase frictional force, then sheet non-feeding is solved, but pressing force increases causing multiple-feeding
Solution Approach 1:
The patent divides the sheet feeding function into two separate rollers: a first feeding roller for normal operation and a second feeding roller activated only when needed. This segmentation allows the system to increase total contact area and frictional force when the first roller slips, while the second roller's selective engagement prevents continuous excessive pressing force that would cause multiple sheets to feed
3Reliability
If frictional force between sheet-feed roller and sheet is increased by using high friction coefficient material, then sheet non-feeding is prevented, but the device complexity increases
Solution Approach 1:
The patent changes the parameter of contact area rather than relying solely on material friction coefficient. By making the second feeding roller movable and engaging it only when the first roller slips, the system increases frictional force through increased contact area (both rollers contacting the sheet) without requiring complex material science solutions or permanently complex mechanical structures
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
Ensures sheet feeding with increased frictional force without multiple-feeding, resolving sheet-feeding failures by adjusting the contact area dynamically based on sensor feedback.
Implementation Method 1
Each sheet is fed by friction force generated between the sheet-feed roller and the sheet upon rotation of the sheet-feed roller
Implementation Method 2
The second feeding roller at the feeding position is in contact with the sheet and feeds the sheet in the sheet-feeding direction
Data Source
AI summary
A sheet-feeding device includes: a first feeding roller configured to contact a sheet accommodated in a sheet-accommodation portion to feed the sheet; a second feeding roller movable between a non-feeding position and a feeding position; a driving source configured to generate a rotational driving force to the first feeding roller; a transmission portion configured to transmit the rotational driving force to the second feeding roller; a first sensor; a second sensor; and a roller actuating portion. The roller actuating portion is configured to: move the second feeding roller from the non-feeding position to the feeding position in a case where the second detector detects rotation of the first feeding roller is stopped during a sheet-feeding operation; and move the second feeding roller from the feeding position to the non-feeding position in a case where the first sensor detects the sheet-feeding operation is completed for the sheet.