Low-Thermal-Conductivity Conveyance Roller for Toner Uniformity
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Solution Overview
Problem
Existing image forming systems face issues with image unevenness due to temperature differences in toner images at the glass transition temperature, which can occur when the toner image contacts a conveyance roller, leading to unstable contact states and layout restrictions.
Innovation Solution
Incorporating a low-thermal-conductivity conveyance roller downstream of the fixer, which maintains a stable contact state and prevents heat absorption, thereby reducing temperature differences and image unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional conveyance roller is used downstream of the fixer, then the sheet can be conveyed, but the toner image absorbs heat from the roller causing temperature differences and image unevenness at the glass transition temperature
Solution Approach 1:
The patent changes the thermal conductivity parameter of the conveyance roller by using a resin material with specifically controlled thermal conductivity (0.2 W/m·K or less). This parameter change prevents excessive heat transfer from the roller to the toner image, maintaining temperature uniformity and preventing image unevenness during conveyance through the glass transition temperature region.
Solution Approach 2:
The patent applies local quality by using a resin material specifically for the roller surface that contacts the toner image. This material has low thermal conductivity to prevent heat absorption, while other parts of the system can use different materials optimized for their specific functions. The resin layer is applied locally where heat transfer would cause image defects.
2Temperature
If the thermal conductivity of the conveyance roller surface is reduced to prevent image unevenness, then temperature differences are minimized, but the contact state of the roller with the sheet becomes unstable
Solution Approach 1:
The patent uses composite materials structure where a resin material layer with low thermal conductivity is applied on the surface of the conveyance roller. This resin layer prevents heat absorption while the underlying roller structure maintains mechanical stability and proper contact with the sheet. The composite structure combines the thermal insulation properties of resin with the structural integrity of the roller core.
3Reliability
If no conveyance roller is provided in the region where the toner image reaches the glass transition temperature, then image unevenness is prevented, but the layout of conveyance members is restricted
Solution Approach 1:
The patent changes the thermal conductivity parameter of the conveyance roller to enable the roller to function in the glass transition temperature region without causing image unevenness. By using resin material with thermal conductivity of 0.2 W/m·K or less, the roller can be placed flexibly in the conveyance path layout while maintaining image quality, as the low thermal conductivity prevents harmful heat transfer regardless of the roller's position relative to the glass transition temperature zone.
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
The low-thermal-conductivity conveyance roller effectively prevents image unevenness by maintaining consistent contact and reducing thermal conductivity, while allowing for flexible layout designs without increasing costs.
Implementation Method 1
a low-thermal-conductivity conveyance roller that conveys the recording medium while holding the recording medium at a formed nip, the low-thermal-conductivity conveyance roller having a lower thermal conductivity than one or a plurality of other conveyance rollers
Data Source
AI summary
The present invention provides an image forming system including: a fixer that heats and fixes a toner image onto a recording medium; and a low-thermal-conductivity conveyance roller that conveys the recording medium while holding the recording medium at a formed nip, the low-thermal-conductivity conveyance roller having a lower thermal conductivity than one or a plurality of other conveyance rollers located downstream of the fixer and being provided in a predetermined region downstream of the fixer where the toner image that has been heated and fixed reaches a glass transition temperature.