Sheet Cutting Device Oblique Cut Prevention

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Solution Overview

Problem

Conventional sheet cutting devices in image forming apparatuses often experience oblique cutting due to the weight of the sheet, especially when the sheet is not properly secured, leading to suboptimal cutting quality and potential user errors.

Innovation Solution

A sheet cutting device equipped with a cutter, a movable member, a driving device, and a sheet holder that includes a holding member which secures the sheet at the cutting start side, preventing the sheet from falling and thus preventing oblique cutting by moving to a holding position during cutting and returning to a non-holding position afterward.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a projection is provided on the guide plate to prevent oblique cutting, then the sheet can be restrained from oblique movement, but the sheet is not securely held and oblique cutting still occurs depending on sheet thickness and hardness

Engineering Contradiction:
Improveprevention of oblique cuttingVSAvoidsheet holding mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sheet holding member is positioned in advance at the cutting start side before the cutting operation begins. This preliminary positioning ensures the sheet is secured before cutting forces are applied, preventing oblique movement regardless of sheet thickness or hardness variations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sheet holding member acts as an intermediary element between the sheet and the cutting device. It provides a controlled interface that secures the sheet at the critical cutting start side, transferring and stabilizing the sheet position during the cutting process without requiring complex direct fixation mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the sheet is not secured during cutting, then the device structure remains simple, but the sheet may drop due to its own weight causing oblique cutting

Engineering Contradiction:
Improvesheet holding mechanismVSAvoidcutting quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

Instead of securing the entire sheet, the sheet holding member applies localized support only at the cutting start side. This local intervention is sufficient to prevent oblique cutting while maintaining overall structural simplicity and not requiring complex full-sheet fixation mechanisms.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The sheet holding member provides preliminary counter-action against the gravitational force that would cause the sheet to drop. By positioning and securing the sheet at the cutting start side before cutting begins, it preemptively counteracts the weight-induced oblique movement that would otherwise occur during cutting.

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If a projection on the guide plate is used to prevent oblique movement, then some restraint is provided, but oblique cutting occurs when users forget to perform the operation

Engineering Contradiction:
Improveprevention of oblique cuttingVSAvoiduser operation requirement
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The sheet holding member is automatically positioned and activated by the cutting device itself, without requiring separate user intervention. The system self-services by automatically securing the sheet at the cutting start side, eliminating the need for users to remember or perform additional operations to prevent oblique cutting.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The sheet holding function is merged with the cutting device operation. The positioning and activation of the sheet holding member is integrated into the cutting process itself, combining two functions (sheet securing and cutting) into a single automated operation that eliminates user oversight errors.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3539738B1Sheet cutting device and image forming apparatus including the sheet cutting device
Publication Date: 2020.10.14 RICOH CO LTD
  • EP3539738B1 patent drawingFigure 1
  • EP3539738B1 patent drawingFigure 2~3
  • EP3539738B1 patent drawingFigure 4~6

AI summary

A sheet cutting device (30) includes a cutter (31), a movable member (33), a driving device (32), and a sheet holder (40). The movable member (33) moves the cutter (31) in a cutting direction. The driving device (32) drives the movable member (33). The sheet holder (40) is disposed on a downstream side of a sheet cutting position of the cutter in a sheet conveyance direction, to hold a sheet. The sheet holder (40) includes a sheet holding member (41) that is disposed on a sheet cutting start side of the cutter (31) and is movable to a sheet holding position and a non-holding position. When the sheet is cut by the cutter (31), the sheet holding member (41) moves to the sheet holding position. After cutting of the sheet has been completed, the sheet holding member moves to the non-holding position.