Sheet Transport Device Nip Control for Small Sheet Stability

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Solution Overview

Problem

Existing sheet transport devices experience a decrease in transporting force for small-size sheets, leading to unstable transport orientation, especially when the nip of pairs of transport rollers is not adjusted according to the sheet size.

Innovation Solution

A sheet transport device with a detector to assess the sheet size and a releasing unit that adjusts the nip of transport rollers by releasing the nip of pairs of transport rollers outside the sheet transport region for smaller sheets, ensuring higher nip pressure is maintained by the central rollers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the nip of all pairs of transport rollers is maintained for transporting small-size sheets, then the transporting force decreases due to pressure distribution, but if the nip is released, the transport reliability improves

Engineering Contradiction:

Improvetransport reliabilityVSAvoidtransporting force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The transport rollers are divided into multiple pairs arranged in the sheet width direction, with each pair independently controllable. The central pair maintains nip for transporting small sheets while outer pairs release nip, segmenting the pressure application to optimize both reliability and force distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The nip state of each roller pair is dynamically adjusted based on detected sheet size. For small sheets, the system transitions from a static all-nip state to a dynamic selective-nip state where only central rollers maintain contact, adapting the pressure distribution to match the sheet dimensions.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multiple pairs of transport rollers are used to transport sheets of various sizes, then the adaptability improves, but the device complexity increases

Engineering Contradiction:

Improvesheet size adaptabilityVSAvoidroller control complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Multiple roller pairs are segmented and independently controlled based on their positional relationship to the sheet center. The control system simplifies complexity by using a systematic approach: detect sheet size, identify central region, and apply nip only to rollers within that region, making the complex system manageable through spatial logic.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system performs preliminary detection of sheet size before transport begins. Based on this advance information, the controller pre-configures which roller pairs should maintain nip and which should release, preparing the optimal pressure distribution pattern before the sheet enters the transport region.

Inventive Principle:

Principle #10Preliminary action

3Stress or pressure

If the nip pressure is distributed across all roller pairs, then the pressure per unit area decreases for small sheets, but maintaining all nips ensures broader coverage

Engineering Contradiction:

Improvenip pressureVSAvoidcontact area

Core Design Contradiction:

Stress or pressureVSArea of stationary object

Solution Approach 1:

Instead of uniform nip pressure across all rollers, the system applies local quality by concentrating nip pressure only on central rollers that correspond to the sheet's actual width. This creates a non-uniform pressure distribution where pressure is intensive in the relevant local area (under the sheet) and zero in irrelevant areas (outside the sheet), optimizing both pressure magnitude and contact area efficiency.

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 solution stabilizes the transport orientation of small-size sheets by maintaining higher nip pressure with central rollers, preventing the decrease in transporting force and ensuring stable sheet transport.

Implementation Method 1

The detector detects a size of the transported sheet

Methodology Applied

Scientific EffectOptical detection:

Implementation Method 2

The releasing unit releases the nip of one or more of the pairs of transport rollers outside a transport region of the sheet based on the size of the sheet detected by the detector

Methodology Applied

Scientific EffectMechanical pressure release:

Data Source

PatentUS11425274B2Sheet transport device, image reading device, and image forming apparatus

Publication Date: 2022.08.23 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A sheet transport device includes a sheet transport unit, a detector, and a releasing unit. The sheet transport unit transports a sheet by nipping the sheet in a nip between multiple pairs of transport rollers arranged in a sheet width direction intersecting a sheet transport direction. The detector detects a size of the transported sheet. The releasing unit releases the nip of one or more of the pairs of transport rollers outside a transport region of the sheet based on the size of the sheet detected by the detector.