Feeding Roller Segmentation for Sheet Jamming

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Solution Overview

Problem

Conventional sheet feeding devices in image recording apparatuses suffer from sheet jamming and printing quality deterioration due to increased resistance and banding issues during sheet entry, caused by the design of drive and driven rollers.

Innovation Solution

The feeding device incorporates a driven roller with a toothed wheel portion and a contactable portion, where the toothed wheel portion is positioned symmetrically and the contactable portion is arranged to minimize overlap with the drive roller, reducing resistance and wear, and utilizing inclined surfaces to maintain positional alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the toothed wheel portion of the driven roller is deeply received in the annular groove without its radially outer end portion being in contact with the drive roller, then the sheet can be held in close contact with the drive roller, but the leading end of the sheet upon entrance is brought into contact with a portion of the rowel close to the axis, causing the rowel to rotate poorly and making sheet entry difficult

Engineering Contradiction:

Improvesheet positioning precisionVSAvoidsheet entry smoothness

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The driven roller is divided into a toothed wheel portion (rowels) and a contactable portion (smooth surface). The contactable portion with diameter smaller than the toothed wheel portion is positioned to contact the drive roller first during sheet entry, while the toothed wheel portion is received in the annular groove. This segmentation allows different parts of the driven roller to perform different functions at different stages of sheet feeding.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contactable portion is designed to make initial contact with the drive roller before the toothed wheel portion engages. This preliminary action creates space for the sheet to enter smoothly between the rollers without the leading end contacting the rowel teeth, preventing jamming during sheet entry.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the toothed wheel portion is positioned to overlap significantly with the drive roller, then the sheet can be held firmly, but the resistance during sheet entry increases, causing banding and deterioration in printing quality

Engineering Contradiction:

Improvesheet holding firmnessVSAvoidbanding and printing quality deterioration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The driven roller is segmented into a toothed wheel portion for firm sheet holding and a contactable portion with smaller diameter for reduced resistance during entry. The contactable portion contacts the drive roller first, reducing the overlap effect during sheet entry, while the toothed wheel portion maintains firm holding during normal operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the driven roller have different local qualities: the contactable portion has a smaller diameter and smooth surface for reducing entry resistance, while the toothed wheel portion has a larger diameter and toothed structure for firm sheet holding. This local differentiation resolves the contradiction between firm holding and reduced resistance.

Inventive Principle:

Principle #3Local quality

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 configuration ensures accurate sheet feeding without banding and printing quality deterioration, by reducing the overlap and resistance during sheet entry, and maintaining the positional relationship between rollers.

Implementation Method 1

the driven roller is biased toward the drive roller

Methodology Applied

Scientific EffectElastic force: Elasticity

Implementation Method 2

each of the rowels is displaced by a tension force of the sheet (held between the drive and driven rollers), radially outwardly toward outside the corresponding annular groove, against a biasing force generated by the spring

Methodology Applied

Scientific EffectTension force: Tension

Implementation Method 3

the drive and driven rollers cooperate with each other to feed a sheet in a feeding direction while holding the sheet therebetween

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS7661674B2Feeding device and image recording apparatus equipped with the feeding device

Publication Date: 2010.02.16 BROTHER KOGYO KK

AI summary

A feeding device including a drive roller and a driven roller opposed to the drive roller and biased toward the drive roller, such that the drive and driven rollers cooperate to feed a sheet while holding the sheet therebetween. The driven roller includes a toothed wheel portion and a contactable portion having a diameter smaller than that of the toothed wheel portion. The drive roller includes first and second portions. A radially outer end of the second portion is more distant from an axis of the drive roller than a radially outer end of the first portion. During absence of the sheet between the drive and driven rollers, the contactable portion of the driven roller is held in contact at its circumferential surface with a circumferential surface of the second portion of the drive roller, while a radially outer end of the toothed wheel portion is not in contact with a circumferential surface of the first portion. Also disclosed is an image recording apparatus including the above-described feeding device.