Fixing Belt Thermal Conductor for Uniform Heating
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face challenges in efficiently heating and maintaining the optimal temperature across various sheet sizes, leading to overheating in non-conveyance spans and reduced productivity due to the limited number of heaters and thermal conductivity issues.
Innovation Solution
The proposed fixing device incorporates a fixing belt heated by primary and secondary halogen heaters, with a nip formation pad featuring a thermal conductor having enhanced thermal conductivity, strategically positioned to diffuse heat and prevent overheating, while maintaining productivity across different sheet sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a limited number of heaters are used to heat the fixing belt, then device complexity is reduced, but overheating occurs in non-conveyance spans and heating uniformity deteriorates
Solution Approach 1:
A thermal conductor is introduced as an intermediary component between the heaters and the fixing belt. This thermal conductor has high thermal conductivity and is positioned to extend into the non-conveyance span, acting as a heat bridge that distributes heat uniformly across the fixing belt surface, preventing localized overheating while maintaining energy efficiency.
Solution Approach 2:
The patent changes the thermal conductivity parameter by introducing a material with high thermal conductivity (greater than that of the base) into the nip formation pad. This parameter change enables more efficient heat distribution from the heaters to the fixing belt, achieving uniform temperature distribution without requiring additional heaters.
2Temperature
If the thermal conductor extends further outboard to better distribute heat, then temperature uniformity improves, but heat loss increases and energy efficiency deteriorates
Solution Approach 1:
The thermal conductor is designed with spatially varying properties: it extends further outboard in the non-conveyance span where heat distribution is needed, while maintaining appropriate length in the conveyance span to minimize heat loss. The base material and thermal conductor material are selected to provide optimal thermal conductivity at different locations, achieving local optimization of heat distribution versus energy conservation.
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 suppresses overheating in non-conveyance spans and ensures consistent heating of the fixing belt, enhancing productivity and fixing speed by optimizing thermal conductivity and heat distribution.
Implementation Method 1
The nip formation pad includes a base and at least one thermal conductor being interposed between the base and the fixing nip and having a thermal conductivity greater than a thermal conductivity of the base
Implementation Method 2
A primary heater, disposed opposite an inner circumferential surface of the fixing belt, heats the fixing belt. The primary heater includes a center heat generator disposed opposite a center span of the fixing belt
Data Source
AI summary
A fixing device includes a fixing belt and an opposed rotator to press against a nip formation pad via the fixing belt to form a fixing nip between the fixing belt and the opposed rotator. A primary heater and a secondary heater heat the fixing belt. The secondary heater includes a lateral end heat generator. The nip formation pad includes a base and at least one thermal conductor being interposed between the base and the fixing nip and having a thermal conductivity greater than a thermal conductivity of the base. The at least one thermal conductor includes an outboard edge disposed between an inboard edge and an outboard edge of the lateral end heat generator and disposed outboard from a conveyance span of the fixing belt in an axial direction of the fixing belt, where a recording medium is conveyed over the fixing belt.