Conveyance Guide Curvature for Sheet Stability

Solution Overview

Problem

Image formation apparatuses face increased conveyance resistance and sheet deformation issues due to curved conveyance paths, particularly affecting thin and low-stiffness sheets, as existing solutions either increase resistance excessively or lead to buckling.

Innovation Solution

The apparatus features a pair of conveyance guides with an inner guide overhanging towards the outer guide beyond the external common tangent of the rollers, forming a linearly continuous guide surface, and incorporating rib and surface guide parts to manage sheet orientation and reduce contact pressure, thereby stabilizing sheet conveyance and minimizing image defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the inner guide is greatly retracted to the inside of the curved conveyance path to control conveyance resistance, then the conveyance resistance is reduced, but the gap between the inner guide and outer guide becomes large causing thin and low-stiffness sheets to become buckled

Engineering Contradiction:

Improveconveyance resistanceVSAvoidsheet buckling

Core Design Contradiction:

ForceVSStability of the object's composition

Solution Approach 1:

The guide surface is designed with different curvature characteristics in different regions: the inner guide has a linearly continuous guide surface in the inner region with smaller curvature radius, while the outer guide has a gently curved surface in the outer region with larger curvature radius. This local differentiation allows the inner guide to be retracted (reducing resistance) while maintaining appropriate gap spacing (preventing buckling) through the varying geometric properties across the guide surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs varying curvature radii in the guide surface design. The inner guide features a smaller curvature radius in the inner region to reduce conveyance resistance, while the outer guide maintains a larger curvature radius to prevent sheet buckling. This differential curvature approach resolves the contradiction by allowing the guides to be positioned optimally for both resistance reduction and sheet stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Force

If the outer guide is gently curved to control conveyance resistance for thick and high-stiffness sheets, then the conveyance resistance is controlled, but the gap between guides remains large causing thin and low-stiffness sheets to become buckled

Engineering Contradiction:

Improveconveyance resistanceVSAvoidsheet conveyance stability

Core Design Contradiction:

ForceVSEase of operation

Solution Approach 1:

The guide surface is designed with different curvature characteristics in different regions: the inner guide has a linearly continuous guide surface in the inner region with smaller curvature radius, while the outer guide has a gently curved surface in the outer region with larger curvature radius. This local differentiation allows the inner guide to be retracted (reducing resistance) while maintaining appropriate gap spacing (preventing buckling) through the varying geometric properties across the guide surface.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs varying curvature radii in the guide surface design. The inner guide features a smaller curvature radius in the inner region to reduce conveyance resistance, while the outer guide maintains a larger curvature radius to prevent sheet buckling. This differential curvature approach resolves the contradiction by allowing the guides to be positioned optimally for both resistance reduction and sheet stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Ease of operation

If a curved conveyance path is used to convey sheets from separation and feed roller pair to conveyance roller pair, then the sheet conveyance is enabled, but the conveyance resistance increases

Engineering Contradiction:

Improvesheet conveyance capabilityVSAvoidconveyance resistance

Core Design Contradiction:

Ease of operationVSForce

Solution Approach 1:

The patent employs varying curvature radii in the guide surface design. The inner guide features a smaller curvature radius in the inner region to reduce conveyance resistance, while the outer guide maintains a larger curvature radius to prevent sheet buckling. This differential curvature approach resolves the contradiction by allowing the guides to be positioned optimally for both resistance reduction and sheet stability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The guide surface parameters (curvature radius, guide position) are optimized to balance conveyance resistance and sheet stability. By adjusting these geometric parameters, the system enables curved path conveyance while minimizing resistance increases and preventing sheet deformation.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11616886B2Image formation apparatus

Publication Date: 2023.03.28 CANON KK

AI summary

An image formation apparatus to form an image on a sheet having a width direction includes a separation and feed roller pair having a feed roller, a conveyance roller pair having a driving roller, and a pair of conveyance guides having inner and outer guides. A part of the inner guide overhangs toward an outer guide side from an external common tangent of the feed roller and the driving roller. Points of intersection with the feed roller on the external common tangent are designated as first intersection points and points of intersection with the driving roller on the external common tangent are designated as second intersection points. When ends of the feed and driving rollers serve as vertexes, a guide surface of the inner guide is linearly continuous in the width direction in an inner region on the guide surface of the inner guide formed by connecting the vertexes.