Fixing Device Curie Point Alloy Heat Management
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Solution Overview
Problem
Existing fixing devices with small heat capacity struggle to maintain temperature control, leading to excessive temperature increases in non-contact areas, which can damage components and result in uneven glossiness and hot offset issues, especially when switching between small and large-sized recording sheets, and have poor warm-up properties.
Innovation Solution
A fixing device with a heat generation member that includes a magnetic shunt alloy layer, a conductive heat generation layer, and a low resistance conductive layer, integrated into an endless belt system, where the magnetic shunt alloy layer is made of Ni—Fe or Ni—Fe—Cr alloys, and the Curie point is between 180° C and 240° C, and a low friction layer is used to reduce sliding friction, allowing for efficient heat management and energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heat generation member has a small heat capacity to reduce warm-up period, then the warm-up period is shortened, but the temperature of contactless portions abnormally increases causing thermal damage and uneven glossiness
Solution Approach 1:
The patent applies parameter changes by utilizing the Curie point temperature characteristic of magnetic shunt alloy. When the contactless portions reach the Curie point (180-240°C), the magnetic shunt alloy loses its magnetic properties, causing magnetic flux to leak and reducing heat generation in those areas. This automatic parameter change based on temperature prevents excessive temperature increase while maintaining rapid warm-up capability.
Solution Approach 2:
The fixing device implements self-service through self-temperature control. The magnetic shunt alloy automatically regulates heat generation in contactless portions by losing magnetism at the Curie point, eliminating the need for external temperature control mechanisms. The system self-adjusts to prevent thermal damage without additional control systems.
2Productivity
If small-sized recording sheets are continuously used, then productivity is improved, but the contactless portions experience abnormal temperature increase leading to component deterioration
Solution Approach 1:
The magnetic shunt alloy's Curie point characteristic provides automatic parameter change based on temperature. During continuous printing of small sheets, contactless portions that exceed the Curie point temperature automatically lose magnetic properties, reducing heat generation and preventing thermal damage to components, thus maintaining reliability during high-productivity operation.
Solution Approach 2:
The system implements feedback through the temperature-dependent magnetic properties of the shunt alloy. When contactless portions overheat, the magnetic flux distribution automatically changes due to loss of magnetism at the Curie point, providing negative feedback that prevents further temperature increase and protects component durability during continuous operation.
3Adaptability or versatility
If a large-width recording sheet is used after small-sized sheets, then adaptability is improved, but hot offset occurs at the outer edges causing uneven glossiness
Solution Approach 1:
The magnetic shunt alloy's temperature-dependent magnetic properties create parameter changes that affect heat distribution. When switching from small to large sheets, any residual heat in contactless portions that reached the Curie point will have reduced heat generation capability, helping to prevent hot offset and glossiness unevenness during sheet size transitions.
4Temperature
If magnetic shunt alloy is used to control temperature in contactless portions, then temperature control is improved, but device complexity increases due to additional layers
Solution Approach 1:
The patent employs composite materials by integrating magnetic shunt alloy into the heat generation member structure. This composite approach combines the heat generation function with temperature control functionality in a single integrated component, achieving precise temperature control in contactless portions while maintaining relatively simple overall device structure.
Solution Approach 2:
The magnetic shunt alloy layer serves multiple functions: it participates in heat generation through magnetic flux conduction and simultaneously provides temperature control in contactless portions by losing magnetism at the Curie point. This multi-functionality reduces the need for separate temperature control mechanisms, thereby limiting the increase in device complexity.
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 solution effectively controls temperature in both contact and non-contact areas, preventing thermal damage, maintaining even glossiness, and achieving rapid warm-up with reduced energy consumption and improved durability.
Implementation Method 1
the Curie point is between 180° C and 240° C
Implementation Method 2
magnetic flux, which is generated by supplying an alternating electric current to excitation coil
Implementation Method 3
heat sources of an induction heating type
Implementation Method 4
conductive heat generation layer provided at a heat generation member
Data Source
AI summary
Disclosed is a fixing device having a self-temperature control function, and reducing a heat capacity of a heat generation member for saving energy and achieving good warm-up property. The fixing device includes a fixed plate inside a closed rotation path of a belt, contacting an inner circumferential surface of the belt, substantially opposed to an excitation coil with the belt therebetween, keeping the belt on the rotation path. The fixed plate includes: a magnetic shunt alloy layer made of a magnetic shunt alloy; a conductive heat generation layer being disposed toward a main surface of the magnetic shunt alloy layer facing the belt, being made of a conductor other than the alloy, and being thinner than the alloy layer; and a low resistance conductive layer being disposed toward another main surface, having a lower electric resistance value than the heat generation layer, and being thicker than the heat generation layer.