Asymmetric Heating for Sheet Curl Control

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Solution Overview

Problem

Existing drying devices in image forming apparatuses face challenges in effectively preventing back curl and cockling of sheets, leading to conveyance failures and reduced stackability, as they often heat the liquid applied face at a higher temperature than the opposite face, exacerbating curl formation.

Innovation Solution

A novel heating device configuration featuring a first heat member and a second heat member, where the second heat member heats the opposite face of the sheet at a higher temperature than the first heat member, counteracting the curling force and preventing back curl by applying heat uniformly across the sheet.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the liquid applied face is heated at a higher temperature to dry the sheet efficiently, then the drying speed is improved, but back curl and cockling occur due to uneven heat distribution

Engineering Contradiction:

Improvedrying speedVSAvoidsheet flatness

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies different heating temperatures to different regions of the sheet. The opposite face (non-liquid applied face) is heated at a higher temperature than the liquid applied face. This local differentiation in heating strategy compensates for the moisture distribution pattern, preventing back curl while maintaining efficient drying speed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heating device uses asymmetric temperature distribution across the sheet faces. Instead of uniform heating, the system deliberately creates temperature asymmetry by heating the opposite face at higher temperature than the liquid applied face, which counteracts the natural curling tendency caused by liquid application on one side only.

Inventive Principle:

Principle #4Asymmetry

2Reliability

If the sheet is heated to eliminate cockling and ensure close contact with the heat roller, then drying efficiency is improved, but back curl is exacerbated due to temperature differential

Engineering Contradiction:

Improvesheet contact qualityVSAvoidsheet curvature

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The system applies preliminary heating to the opposite face before the sheet contacts the heat roller. By pre-heating the opposite face at higher temperature, the sheet maintains flat contact with the roller during drying, preventing back curl formation that would otherwise occur due to the temperature differential between faces.

Inventive Principle:

Principle #9Preliminary anti-action

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 effectively restrains back curl and cockling, ensuring smooth conveyance and increased stackability of sheets by balancing heat distribution across the sheet, thereby enhancing the efficiency and reliability of the drying process.

Implementation Method 1

a first heat member (43) that heats a sheet (P) on a liquid applied face (Pa)

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

a second heat member (40) that heats the sheet (P) on an opposite face (Pb) opposite the liquid applied face (Pa)

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

heat a sheet to dry liquid on the sheet

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS11780244B2Heating device, liquid applying apparatus, image forming apparatus, post-processing apparatus, and conveying device

Publication Date: 2023.10.10 RICOH CO LTD

AI summary

A heating device includes a first heat member and a second heat member. The first heat member is configured to heat a sheet on a liquid applied face. The second heat member is configured to heat the sheet on an opposite face opposite the liquid applied face of the sheet. A temperature of the second heat member to heat the sheet is higher than a temperature of the first heat member to heat the sheet.