Fixing Device Heater Soaking Member Thermal Capacity
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Solution Overview
Problem
Temperature unevenness in the fixing device of an image forming apparatus leads to uneven gloss in images formed on sheets, as the existing heating mechanisms do not effectively manage temperature distribution across the cylindrical film and soaking member.
Innovation Solution
The fixing device incorporates a heater unit with a soaking member having varying thermal capacities per unit length, where the thermal capacity at one position is lower than at another, to control heat transfer and reduce temperature unevenness by adjusting the contact length and area with the heater unit, thereby optimizing the temperature increase rate across the cylindrical film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heater unit heats the cylindrical film uniformly, then the temperature distribution is improved, but the heating efficiency and temperature increase rate are reduced
Solution Approach 1:
The soaking member is designed with non-uniform thermal capacity along its length, with different sections having different thermal capacities. This local variation in thermal properties allows certain sections to heat up faster while others maintain more stable temperatures, achieving both uniform overall temperature distribution and acceptable heating efficiency
Solution Approach 2:
The patent changes the thermal capacity parameter of the soaking member along its length to optimize heat distribution. By varying this physical parameter spatially, the system achieves better temperature uniformity without completely sacrificing heating speed
2Loss of energy
If the contact area between the soaking member and heater unit is increased, then heat transfer efficiency is improved, but temperature control precision is reduced
Solution Approach 1:
Different sections of the soaking member have different contact areas with the heater unit, creating local variations in heat transfer characteristics. This allows the system to optimize both overall heat transfer efficiency and local temperature control precision simultaneously
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 reduces temperature unevenness on the cylindrical film, ensuring consistent heating and improving the uniformity of the image gloss by managing heat transfer effectively between the heater unit and the soaking member.
Implementation Method 1
The soaking member is configured to come into contact with a second surface of the heater unit. A thermal capacity of the soaking member per unit length at the second position in the second direction is lower than a thermal capacity of the soaking member per unit length at the first position in the second direction.
Implementation Method 2
If the heater unit heats the cylinder, the contact body is configured to be heated at a first position in the second direction at a first temperature increase rate. If the heater unit heats the cylinder, the contact body is configured to be heated at a second position in the second direction at a second temperature increase rate that is lower than the first temperature increase rate.
Data Source
AI summary
A fixing device includes a cylinder, a heater, a contact body, and a soaking member. The heater has a first surface and an opposing second surface. The heater includes a heating element extending along a longitudinal direction of the heater. The first surface engages with an inner surface of the cylinder. The contact body is configured to engage with the inner surface of the cylinder. The contact body is configured to be heated at a first position along the longitudinal direction at a first temperature increase rate and at a second position along the longitudinal direction at a second temperature increase rate that is lower than the first temperature increase rate. The soaking member is positioned to engage with the opposing second surface of the heater. The soaking member has a second thermal capacity lower than a first thermal capacity at the respective second and first positions.