Sheet Conveyance Pre-Separation Unit with Asymmetric Curvature

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Solution Overview

Problem

Existing image reading devices face issues with document skew and multiple feeding due to the design of pre-separation units, which can increase document skew and fail to securely separate sheets when documents are skewed or closely aligned.

Innovation Solution

A sheet conveyance unit with a pre-separation unit featuring a downward sloped portion and an upward sloped portion, where both ends of the upward sloped portion are sloped more gently than the center, to guide the leading edge of each sheet diagonally and prevent skew, ensuring secure separation and feeding of sheets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a pre-separation unit with an upward sloped portion is used to separate sheets, then sheet separation is improved, but document skew increases

Engineering Contradiction:

Improvesheet separationVSAvoiddocument skew

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The upward sloped portion is designed with asymmetric curvature where both ends are sloped more gently than the center. This asymmetric design allows the leading edge of the sheet to be guided smoothly while preventing lateral corners from contacting the sloped surface, thereby maintaining sheet separation effectiveness without increasing document skew.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The upward sloped portion features a curved surface instead of a straight inclined plane. The curvature is designed such that the center has a steeper slope and the ends have gentler slopes, creating a smooth guiding path for the sheet's leading edge that prevents skew while maintaining separation.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Ease of operation

If a downward sloped portion is added to guide the leading edge diagonally, then sheet guidance is improved, but device complexity increases

Engineering Contradiction:

Improvesheet guidanceVSAvoidpre-separation unit structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The downward sloped portion and upward sloped portion are merged into a single continuous guiding surface. This integration allows the leading edge of the sheet to be guided diagonally downward and then smoothly transitioned to the upward slope, improving sheet guidance while avoiding the need for separate discrete components.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS8994963B2Sheet conveyance unit, image reading device, and image forming apparatus

Publication Date: 2015.03.31 RICOH CO LTD

AI summary

A sheet conveyance unit including a sheet tray on which a stack of sheets is placed, a sheet feed member to feed sheets from the stack of sheets, a separation/feed unit to separate a topmost sheet from the rest of sheets fed by the sheet feed member and feed the topmost sheet to a predetermined position, and a pre-separation unit disposed between the sheet tray and the separation/feed unit. The pre-separation unit includes a downward sloped portion to guide a leading edge of each sheet diagonally downward, and an upward sloped portion provided downstream from the downward sloped portion in a conveyance direction of the sheets to guide the leading edge of each sheet diagonally upward. Both ends of the upward sloped portion in a lateral direction are sloped upward more gently than the center of the upward sloped portion.