Elastic Buffer for Sheet Skew Correction in Image Formers

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Solution Overview

Problem

Conventional image forming apparatuses face issues with sheet skew correction, particularly when handling high-rigidity sheets, leading to potential slipping between the sheet feeding roller and the sheet, resulting in defective conveyance due to weakened press contact force caused by the separation roller being pressed down.

Innovation Solution

An image forming apparatus incorporating a plate-like elastic member capable of elastic deformation, positioned downstream of the sheet feeding unit, which abuts against the warped sheet to reduce the force pressing down the separation roller away from the sheet feeding roller, ensuring consistent conveyance force is maintained even for high-rigidity sheets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the leading edge of the sheet abuts against the nip portion of the stopped registration roller pair to form a warp, then skew correction is achieved, but the separation roller is pressed down away from the sheet feeding roller causing weakened press contact force

Engineering Contradiction:

Improveskew correction accuracyVSAvoidpress contact force between sheet feeding roller and sheet

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

A buffer member is introduced as an intermediary element between the sheet feeding roller and the separation roller. This buffer member absorbs the pressing force generated when the sheet leading edge abuts against the registration roller pair, preventing the separation roller from being pressed down away from the sheet feeding roller, thereby maintaining adequate press contact force while still enabling skew correction

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The buffer member is positioned in advance to counteract the harmful pressing force before it can cause the separation roller to detach from the sheet feeding roller. By providing this preliminary counter-action, the system maintains the necessary press contact force for reliable sheet feeding while allowing the skew correction mechanism to function

Inventive Principle:

Principle #9Preliminary anti-action

2Ease of operation

If the press contact force between sheet feeding roller and sheet is weakened, then the sheet can be fed smoothly, but the required conveyance force for high rigidity sheets cannot be obtained resulting in slipping

Engineering Contradiction:

Improvesheet feeding smoothnessVSAvoidconveyance force sufficiency for high rigidity sheets

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The buffer member serves as a mediator that regulates the force transmission between the sheet feeding roller and the separation roller. It prevents excessive pressing force from detaching the separation roller, thereby maintaining consistent press contact force that is sufficient for conveying high rigidity sheets without slipping, while still allowing smooth sheet feeding

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the separation roller is pressed down away from the sheet feeding roller, then the sheet can enter the registration roller pair, but the conveyance of the sheet is suspended due to insufficient conveyance force

Engineering Contradiction:

Improvesheet entry into registration roller pairVSAvoidsheet conveyance continuity

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The buffer member is positioned between the sheet feeding roller and separation roller to mediate the force interaction. When the sheet leading edge abuts against the registration roller pair, the buffer member absorbs the resulting pressing force, preventing the separation roller from detaching and ensuring continuous, uninterrupted sheet conveyance while still allowing the sheet to enter the registration roller pair

Inventive Principle:

Principle #24Intermediary (Mediator)

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 maintains the required conveyance force for high-rigidity sheets, preventing slipping and ensuring accurate sheet conveyance by reducing the force that would otherwise cause the separation roller to separate from the sheet feeding roller, thus enhancing the reliability of the image forming process.

Implementation Method 1

a plate-like elastic member capable of elastic deformation and configured to abut against the sheet, which is warped as a result of abutting against the registration unit

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS9061846B2Image forming apparatus

Publication Date: 2015.06.23 CANON KK

AI summary

An image forming apparatus includes a registration roller pair, which is arranged on a downstream side in a sheet feeding direction with respect to a nip portion of a sheet feeding roller and a separation roller, configured to cause a leading edge of a sheet, the sheet is conveyed while being nipped by the sheet feeding roller and the separation roller, to abut against the stopped registration roller pair to form warping in the sheet. And, a backup sheet is deformed toward a separation roller side by abutting against the sheet, which has been warped by abutting the leading edge of the sheet against the registration roller pair, from the separation roller side in a vicinity of the downstream side in the sheet feeding direction with respect to the nip portion.