Fixing Device Magnetic Flux Control for Uniform Heating
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Solution Overview
Problem
The existing fixing devices in image forming apparatuses face temperature variations in the axial direction of the fixing rotary body, leading to inconsistent toner image gloss on large recording media due to uneven heat distribution, which is exacerbated by the heat drawn from the degausser affecting the heat generation layer's efficiency and self-temperature control.
Innovation Solution
The implementation of a fixing device with a temperature sensitive magnetic body and a degausser made of a non-magnetic material with an electrical resistivity lower than the magnetic body, positioned with an interval of 4.2 mm to 8.2 mm from the exciting coil, to create a heating region and non-heating region on the heat generation layer, enhancing both heat generation efficiency and self-temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the degausser is positioned close to the exciting coil to achieve self temperature control, then temperature uniformity is improved, but heat generation efficiency deteriorates due to heat drawn from the heat generation layer
Solution Approach 1:
The patent introduces a temperature sensitive magnetic body as an intermediary component positioned between the exciting coil and the degausser. This mediator selectively transmits or blocks magnetic flux based on temperature, enabling the degausser to receive sufficient magnetic flux for self temperature control without directly drawing heat from the heat generation layer, thus resolving the contradiction between temperature uniformity and heat generation efficiency
Solution Approach 2:
The patent utilizes the temperature-dependent magnetic properties of the temperature sensitive magnetic body (specifically the Curie temperature characteristic) to dynamically change the magnetic flux transmission parameter. Below the Curie temperature, the magnetic body transmits flux to the degausser; above the Curie temperature, it blocks flux, thereby automatically regulating the interaction between the degausser and heat generation layer to maintain both temperature uniformity and heat generation efficiency
2Loss of time
If the heat generation layer is made thin to enable quick heating, then warm-up time is reduced, but temperature variation in the axial direction increases
Solution Approach 1:
The temperature sensitive magnetic body acts as a mediator that distributes magnetic flux more uniformly across the axial direction of the heat generation layer. By positioning it between the exciting coil and the degausser, it ensures that even thin heat generation layers receive sufficient and uniformly distributed magnetic flux, enabling quick heating while maintaining temperature uniformity in the axial direction
Solution Approach 2:
The patent applies the concept of local quality by using the temperature sensitive magnetic body to create localized magnetic flux distribution that compensates for axial variations. The magnetic body's temperature-dependent properties allow it to adjust magnetic flux transmission locally across the axial direction, ensuring uniform heating even when the heat generation layer is thin
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 ensures consistent heat distribution across the fixing rotary body, reducing warm-up time and preventing overheating, thereby maintaining the desired fixing temperature and image quality on various media sizes.
Implementation Method 1
the heat generation layer generates heat by a magnetic flux from an exciting coil
Implementation Method 2
a temperature sensitive magnetic body... loses magnetism at a temperature which is defined by a Curie temperature
Implementation Method 3
the metal plate to generate a repulsive magnetic flux that offsets the magnetic flux from the exciting coil
Data Source
AI summary
A fixing device includes an exciting coil to generate a magnetic flux and a heat generation layer disposed opposite the exciting coil to generate heat by the magnetic flux from the exciting coil. A temperature sensitive magnetic body, disposed opposite the exciting coil via the heat generation layer, obtains and loses magnetism at a temperature defined by a Curie temperature by composition adjustment to selectively create a heating region and a non-heating region of the heat generation layer. A degausser is made of a non-magnetic material having an electrical resistivity smaller than an electrical resistivity of the temperature sensitive magnetic body. The degausser is disposed opposite the exciting coil with an interval in a range of from about 4.2 mm to about 8.2 mm.