Sheet Buffering Mechanism with Reverse Rollers for Jam Reduction

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing sheet processing apparatuses face challenges in maintaining alignment precision while reducing jam occurrences, particularly when using rotary members that only contact the upper surface of sheets.

Innovation Solution

The development of a sheet processing apparatus that incorporates a buffering mechanism with reverse conveyance rollers and in-body discharge rollers, allowing for controlled sheet alignment and conveyance to prevent jams, while maintaining precision through strategic offsetting of sheets in the buffering portion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a rotary member (paddle or belt) that contacts only the upper surface of the sheet is used for alignment, then the device complexity is reduced, but the alignment precision cannot be maintained while reducing jams

Engineering Contradiction:
Improvealignment mechanism complexityVSAvoidsheet alignment precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The invention transitions from single-surface contact alignment (upper surface only) to multi-surface contact alignment by introducing reverse conveyance rollers that contact the lower surface of the sheet. This dimensional change in contact points enables simultaneous achievement of alignment precision and jam reduction without increasing overall device complexity

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If the conveyance force applied by the rotary member to the sheet is increased to improve alignment precision, then alignment precision is improved, but jam occurrence increases

Engineering Contradiction:
Improvesheet alignment precisionVSAvoidjam occurrence
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The reverse conveyance rollers apply conveyance force in the opposite direction to the rotary member's force. This counterbalancing approach distributes the total conveyance force, preventing excessive force concentration that causes sheet crumpling and jams, while maintaining sufficient force for precise alignment through coordinated action

Inventive Principle:
Principle #8Anti-weight (Counterweight)

3Reliability

If the conveyance force applied by the rotary member to the sheet is decreased to reduce jams, then jam occurrence is reduced, but alignment precision deteriorates

Engineering Contradiction:
Improvejam occurrenceVSAvoidsheet alignment precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The invention merges the functions of the rotary member and reverse conveyance rollers into a coordinated alignment system. The combined action of both components provides sufficient total conveyance force for precise alignment while distributing force application to prevent sheet damage and jams

Inventive Principle:
Principle #5Merging (Combining)

4Device complexity

If a simple buffer mechanism is used to prevent paging disorder, then the device complexity is reduced, but alignment precision and jam reduction are not effectively achieved

Engineering Contradiction:
Improvebuffer mechanism complexityVSAvoidsheet alignment precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The buffer mechanism is made dynamic through the reverse conveyance rollers that can actively adjust sheet position and apply controlled conveyance force in the opposite direction. This dynamic capability enables the simple buffer structure to achieve precise alignment and reduce jams without adding complex components

Inventive Principle:
Principle #15Dynamics

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 solution effectively reduces jam occurrences while maintaining high alignment precision, even when processing multiple sheets, thereby enhancing the productivity and reliability of the image forming system.

Implementation Method 1

a conveyance roller pair that nips and conveys a sheet

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

a moving member that moves the sheet in a direction following the sheet discharge direction of the conveyance roller pair

Methodology Applied
Scientific EffectMechanical Force: Force

Data Source

PatentEP3789827B1Sheet processing apparatus and image forming system
Publication Date: 2025.04.23 CANON KK
  • EP3789827B1 patent drawingFigure 1
  • EP3789827B1 patent drawingFigure 2
  • EP3789827B1 patent drawingFigure 3A~3D

AI summary

A sheet processing includes a first conveyance path (81), a buffering portion (4B), a second conveyance path (82), a conveyance roller pair (29), a supporting portion (32), a moving member (33), a regulating portion (39), and a processing unit (51). The buffering portion (4B) is configured to superimpose a first sheet and a second sheet on each other in a state of being offset from each other in a sheet conveyance direction. An offset amount, by which a leading end of the first sheet in the sheet conveyance direction projects downstream in the sheet conveyance direction with respect to a leading end of the second sheet in the sheet conveyance direction in a state before the first sheet and the second sheet are discharged onto the supporting portion (32), is larger than a distance from a sheet contact position of the moving member (33) to the regulating portion (39) in the sheet conveyance direction.