Fixing Roller Curvature and Roughness for Sheet Separation
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Solution Overview
Problem
Conventional fixing devices with smooth fluorine-based resin surfaces suffer from sheet jamming issues due to poor sheet separating properties and deteriorated toner and paper powder releasability, leading to image noise and reliability problems.
Innovation Solution
The fixing device features a surface with an arithmetic average roughness of 0.1 μm to 1.3 μm, made of fluorine-based resin, with one member curved to protrude at the nip section's downstream end, enhancing sheet separation and toner/paper powder releasability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth surface (Ra ≤ 0.05 μm) made of fluorine-based resin is used for the nip section members, then releasability of toner and paper powder is enhanced, but sheet separating property deteriorates causing jam generation
Solution Approach 1:
The invention applies different surface roughness characteristics to different regions of the nip section members. The main nip section maintains a smooth surface (Ra ≤ 0.05 μm) for good releasability, while the downstream end section has a protruding curved portion with different surface properties to enhance sheet separation. This local differentiation resolves the contradiction between maintaining smoothness for releasability and creating separation capability.
Solution Approach 2:
The invention introduces a curved protruding portion at the downstream end section of the nip section members. This curved geometry helps guide sheets off the member and prevents winding, thereby improving sheet separation. The curvature is specifically designed to work with the sheet conveyance direction and provides a gentle separation action without causing damage.
2Object-generated harmful factors
If additives are added to fluorine-based resin to improve sheet separation, then sheet separating property improves, but surface unevenness increases causing toner and paper powder to adhere to the surface
Solution Approach 1:
Instead of adding additives throughout the entire fluorine-based resin surface, the invention creates surface unevenness only in the protruding curved portion at the downstream end section. The main nip section remains smooth with Ra ≤ 0.05 μm to maintain releasability, while only the specific separation region has the modified surface properties needed for sheet separation.
Solution Approach 2:
The nip section member is segmented into different functional zones: a main nip section with smooth surface for toner and paper powder releasability, and a downstream end section with protruding curved portion for sheet separation. This segmentation allows each zone to have optimized surface characteristics appropriate to its specific function without compromising the other.
3Object-generated harmful factors
If the surface arithmetic average roughness is increased to improve sheet separation, then sheet separating property improves, but image quality deteriorates due to transferred shape of attached substances
Solution Approach 1:
The surface roughness modification is localized exclusively to the protruding curved portion at the downstream end section, while the main nip section maintains a smooth surface with Ra ≤ 0.05 μm. This ensures that the image formation area remains free of surface unevenness that could transfer to toner, while the separation function is provided by the localized geometric feature rather than surface roughness.
Solution Approach 2:
Instead of using increased surface roughness to improve sheet separation, the invention employs a curved protruding geometry. This curved shape provides effective sheet separation through its geometric action on the sheet edges while maintaining a smooth surface that does not transfer to the toner image. The curvature radius and positioning are optimized to achieve separation without compromising image 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 design improves sheet separating properties and toner/paper powder releasability, preventing image noise and jamming caused by toner melting, thus ensuring better image quality and paper feed reliability.
Implementation Method 1
a heating source which heats at least one of the two members to fixing temperature
Implementation Method 2
two members which are put in pressure contact with each other so as to form a nip section for fixation
Data Source
AI summary
There are provided two members which respectively have a form of a cylindrical roller or an endless belt and which are put in pressure contact with each other so as to form a nip section for fixation. There is provided a heating source which heats at least one of the two members to fixing temperature. In an end section corresponding to a downstream side of a nip section with respect to a sheet conveyance direction, one member out of the two members is curved in a state of protruding toward the other member. The one member has a surface made of fluorine-based resin, and an arithmetic average roughness of the surface is in a range of 0.1 μm to 1.3 μm.