Pressure Roller Thermal Conductivity and Hardness Balance
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Solution Overview
Problem
In heat fixing apparatuses, particularly in electrophotographic systems, the temperature rises excessively in the non-sheet feeding region, leading to potential damage and high-temperature offset issues, as existing methods struggle to balance thermal conductivity and hardness of pressure rollers effectively.
Innovation Solution
A pressure roller design featuring a core metal with an elastic layer containing thermal conductive fillers, such as carbon fibers, dispersed within a specific range to achieve optimal thermal conductivity and hardness, ensuring efficient heat transfer and maintaining the desired nip width for effective heat fixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermal conductivity of the pressure roller is enhanced by adding thermal conductive filler, then the temperature rise in the non-sheet feeding portion is reduced, but the hardness of the pressure roller increases
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where the pressure roller has different hardness characteristics in different regions. Specifically, it uses a soft layer (lower hardness) and a hard layer (higher hardness) with the thermal conductive filler concentrated in the hard layer. This allows the region contacting the heating element to have high thermal conductivity while the overall roller maintains appropriate softness for image quality, resolving the contradiction between reducing temperature rise and maintaining proper hardness.
Solution Approach 2:
The patent employs composite materials by combining rubber base material with thermal conductive filler particles (such as carbon black, graphite, or metal powders) in specific proportions. The composite structure allows the pressure roller to achieve both thermal conductivity (to reduce temperature rise in non-sheet feeding regions) and appropriate mechanical properties (hardness and elasticity) by optimizing the type, amount, and distribution of the filler material within the rubber matrix.
2Productivity
If the process speed of the printer is increased, then the productivity is improved, but the temperature rises too much in the non-sheet feeding region
Solution Approach 1:
The patent applies preliminary action by pre-equilibrating the pressure roller's temperature distribution before sheet feeding occurs. The thermal conductive filler in the pressure roller actively conducts heat away from the non-sheet feeding regions during the interval between sheets, pre-cooling these areas. This preliminary heat dissipation prevents excessive temperature accumulation when high-speed continuous printing begins, allowing higher productivity without temperature-related defects.
3Temperature
If the thermal conductivity of the pressure roller is increased to reduce temperature rise, then the endurance of the pressure roller deteriorates
Solution Approach 1:
The patent applies local quality by concentrating the thermal conductive filler in specific layers or regions of the pressure roller rather than uniformly distributing it throughout. The soft layer (without or with minimal filler) maintains excellent elasticity and endurance for reliable operation, while the hard layer (with high filler content) provides the thermal conductivity needed to reduce temperature rise. This spatial separation of functions resolves the contradiction between temperature control and durability.
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 effectively suppresses temperature rises in the non-sheet feeding region, enhancing the endurance and stability of the pressure roller and ensuring stable recording sheet conveyance, while maintaining sufficient thermal conductivity for efficient heat transfer.
Implementation Method 1
an elastic layer containing a thermal conductive filler... effectively suppresses temperature rises in the non-sheet feeding region... ensuring efficient heat transfer
Data Source
AI summary
A pressure roller forms a nip for contacting a heating member to pinch and convey a heat recording material. The roller includes a core metal and an elastic layer containing filler. The elastic layer containing the filler includes thermal conductive filler with a length of not less than 0.05 mm and not more than 1 mm with a thermal conductivity λf in the longitudinal direction in a range of λf≧500 W/(m·k), being dispersed in not less than 5 vol % and not more than 40 vol %. The elastic layer containing the filler has a thermal conductivity λy in the longitudinal direction perpendicular to a recording material conveyance direction, of λy≧2.5 W/(m·k) and an ASKER-C hardness of the filler is not more than 60 degrees. A solid rubber elastic layer with a thermal conductivity λ in a thickness direction of not less than 0.16 W/(m·k) and not more than 0.40 W/(m·k) is included.