Sheet Feeder Friction Roller Torque Control
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Solution Overview
Problem
Existing sheet feeders for image forming devices face issues with excessive torque applied to the sheet feed roller when no sheets are present, leading to potential damage, noise, and instability in sheet feeding due to excessive friction, and double feeding when only a few sheets are stacked, along with reduced frictional force caused by foreign substances on the roller surface.
Innovation Solution
A sheet feeder design incorporating a sheet storing unit with a friction member featuring a roller portion and fibrous members at its outer surface, where the sheet feed roller abuts the friction member when no sheets are present to prevent excessive torque and a rotation suppressing member to maintain frictional force, ensuring stable sheet feeding and preventing double feeding by suppressing the rotation of the friction member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheet feed roller is caused to rotate in the state where the sheet feed roller is in contact with the friction member, then an excessive frictional force is generated between the friction member and the surface of the sheet feed roller, but this causes an excessive torque to be applied to the sheet feed roller leading to potential damage and noise
Solution Approach 1:
A freely rotatable roller is introduced as an intermediary element between the sheet feed roller and the friction member. When no sheet is present, the sheet feed roller contacts the freely rotatable roller instead of the friction member, preventing excessive frictional force and torque. The freely rotatable roller acts as a mediator that eliminates direct contact between the sheet feed roller and friction member under no-sheet conditions.
2Reliability
If a freely rotatable roller connected to a spring is provided to prevent excessive torque when no sheet is present, then the sheet feed roller can abut the peripheral surface of the freely rotatable roller, but this results in double feeding when only a few sheets are stacked on the placing plate
Solution Approach 1:
The friction member is designed with differentiated local properties: a roller portion that contacts the sheet feed roller and multiple fibrous members arranged on its outer peripheral surface. This local quality differentiation enables the friction member to provide appropriate frictional resistance at different locations - the roller portion prevents excessive torque while the fibrous members prevent double feeding by maintaining sufficient friction with the lowermost sheet.
Solution Approach 2:
The friction member combines different material characteristics - a roller portion (smooth, low-friction surface) and fibrous members (high-friction, textured surface). This composite structure allows the friction member to exhibit dual functionality: preventing excessive torque through the roller portion while maintaining sheet separation through the fibrous members' high friction coefficient.
3Reliability
If the friction member is designed as a roller member with fibrous members on its outer surface, then the fibrous members can remove foreign substances from the sheet feed roller surface to restore frictional force, but this increases the complexity of the friction member structure
Solution Approach 1:
The friction member is designed to perform multiple functions simultaneously: the roller portion prevents excessive torque, the fibrous members prevent double feeding by maintaining friction with the lowermost sheet, and the fibrous members also remove foreign substances from the sheet feed roller surface to restore frictional force. This multi-functionality reduces the need for separate 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
The solution effectively prevents excessive torque on the sheet feed roller, maintains stable sheet feeding, and restores frictional force by removing foreign substances, thereby enhancing the reliability and quality of sheet feeding in image forming devices.
Implementation Method 1
a friction member that is provided in a position of the bottom plate that faces the sheet feed roller, and is configured to abut a lowermost one of the sheets stacked in the sheet storing unit
Implementation Method 2
the fibrous members arranged at an outer peripheral surface of the roller portion
Implementation Method 3
since a frictional force generated between the roller surface of the sheet feed roller and the uppermost sheet is greater than a frictional force generated between the uppermost sheet and a sheet underneath the uppermost sheet, sheets are separated one by one
Implementation Method 4
a biasing force of a biasing means places the sheet feed roller in pressure contact with a stack of sheets on the placing plate
Data Source
AI summary
A sheet feeder including (1) a sheet storing unit in which a plurality of sheets are stacked, (2) a sheet feed roller that abuts an uppermost one of the sheets stacked in the sheet storing unit and conveys the sheets in a predetermined conveying direction, (3) a friction member provided in the bottom plate, that abuts a lowermost one of the sheets stacked in the sheet storing unit, and (4) a rotation suppressing member that suppresses rotation of the friction member. Wherein the friction member is a roller member including a roller portion, and a plurality of fibrous members arranged at an outer peripheral surface of the roller portion. Wherein the bottom plate of the sheet storing unit has an opening that houses the friction member. Wherein the sheet feed roller abuts the friction member when there is no sheet in the sheet storing unit.