Sheet Thickness Detection Using Biasing Roller Mechanism

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Solution Overview

Problem

Existing sheet thickness detectors in image forming apparatuses face inaccuracies due to nonuniform roller diameters, leading to gaps that result in variable displacement measurements and reduced accuracy in sheet thickness detection, necessitating increased costs to minimize roller diameter tolerance.

Innovation Solution

A sheet thickness detection system comprising multiple first and second rollers aligned perpendicular to the sheet conveying direction, with a first roller shaft supported by a holder to move in contact/separation direction, biased by a member, and a displacement detector to measure the displacement of the first roller shaft, ensuring accurate thickness detection without gaps between rollers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If nonuniform roller diameters are used, then manufacturing cost is reduced, but measurement precision deteriorates due to gaps causing variable displacement measurements

Engineering Contradiction:

Improveroller manufacturing costVSAvoidsheet thickness detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

A biasing member (spring) is introduced as an intermediary element between the driven roller and the drive roller. This spring applies a pressing force that maintains continuous contact between the rollers, eliminating gaps caused by diameter nonuniformity. The biasing member mediates the interaction between rollers, ensuring stable displacement measurements without requiring reduced manufacturing tolerances

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the physical state of roller contact from intermittent (with gaps) to continuous (with pressing force). By applying a pressing force through the biasing member, the contact pressure parameter is adjusted to eliminate gaps, thereby stabilizing the displacement measurement and improving detection accuracy without affecting manufacturing cost

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If roller diameter tolerance is reduced to eliminate gaps, then measurement precision is improved, but manufacturing cost increases significantly

Engineering Contradiction:

Improvesheet thickness detection accuracyVSAvoidroller manufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Instead of reducing roller diameter tolerance, a biasing member (spring) is introduced as an intermediary to actively compensate for diameter variations. This approach maintains measurement precision by eliminating gaps through applied pressing force, while avoiding the need for expensive precision manufacturing

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transitions from a static roller contact system to a dynamic one where the biasing member continuously adjusts to maintain contact. The spring's elastic deformation allows the system to adapt to diameter variations in real-time, maintaining measurement accuracy without strict manufacturing tolerances

Inventive Principle:

Principle #15Dynamics

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 achieves highly accurate sheet thickness detection by eliminating gaps between rollers, allowing for precise control of conveying operations and image forming processes across varying sheet thicknesses without the need for reduced roller diameter tolerances, thus enhancing operational efficiency and reducing costs.

Implementation Method 1

a biasing member to bias the first roller shaft toward the at least one third roller shaft in the contact/separation direction

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a displacement amount detector to detect an amount of displacement of the first roller shaft in the contact/separation direction

Methodology Applied

Scientific EffectDisplacement detection: Displacement

Data Source

PatentUS9718634B2Sheet thickness detector, sheet conveyor incorporating same, and image forming apparatus incorporating same

Publication Date: 2017.08.01 RICOH CO LTD

AI summary

A sheet thickness detector incorporated in a sheet conveyor and/or an image forming apparatus includes multiple first rollers aligned in a direction perpendicular to a sheet conveying direction, multiple second rollers facing the respective first rollers, a first roller shaft supporting two first rollers, at least one second roller shaft supporting rollers other than the two first rollers, at least one third roller shaft to support at least three second rollers, a first roller shaft holder supporting the first roller shaft to move from the at least one third roller shaft in a contact/separation direction, a biasing member biasing the first roller shaft toward at least one third roller shaft, and a displacement amount detector detecting an amount of displacement of the first roller shaft. A thickness of a sheet between the first and second rollers is detected based on a detection result by the displacement amount detector.