Fixing Roller Demagnetizing Coils for Uniform Induction Heating
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Solution Overview
Problem
Existing electromagnetic induction heat applying systems for fixing devices in image forming apparatuses face issues with temperature distribution, leading to image deterioration and reduced device lifetime due to uneven heating and increased temperature at the ends when smaller sheets are processed, as they lack effective control over magnetic flux cancellation.
Innovation Solution
The implementation of a fixing device with multiple demagnetizing coils stacked in layers over the exciting coil to cancel magnetic flux, allowing for precise control of heat distribution by adjusting the power supply and coil configuration, including central core members made of magnetic material and varying loop spaces to ensure uniform heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a single demagnetizing coil is used to cancel magnetic flux at one end, then temperature increase at non-sheet passage section is controlled, but temperature distribution becomes uneven and fixing performance deteriorates
Solution Approach 1:
The single demagnetizing coil is divided into multiple demagnetizing coils arranged along the axial direction of the fixing roller. Each coil can be independently controlled to cancel magnetic flux at different sections, enabling precise temperature control across the entire width of the fixing roller and achieving uniform temperature distribution for improved fixing performance
Solution Approach 2:
Different demagnetizing coils are positioned at different axial locations to provide localized magnetic flux cancellation. This allows each section of the fixing roller to have customized temperature control according to its specific heating requirements, ensuring optimal fixing performance at each location while maintaining overall temperature uniformity
2Temperature
If demagnetizing coil is configured for post card size, then temperature is controlled for small sheets, but temperature decreases at ends when larger sheets like B5 are fed
Solution Approach 1:
The demagnetizing coils are equipped with independent control mechanisms that allow dynamic adjustment of their operation based on sheet size detection. When processing different sheet sizes, the control system selectively activates or deactivates specific demagnetizing coils to maintain optimal temperature distribution, enabling the system to adaptively handle various sheet formats from post card to B5 and beyond
Solution Approach 2:
The multiple demagnetizing coils create a universal temperature control system that can accommodate various sheet sizes. By strategically positioning and controlling each coil, the system achieves versatile functionality to maintain appropriate temperature distribution whether processing small post card sheets or larger B5 sheets, eliminating the need for dedicated configurations for each sheet size
3Use of energy by stationary object
If heat application width is reduced for energy saving, then calorie consumption decreases, but temperature increases at ends cause damage to elastic member and protecting film
Solution Approach 1:
The demagnetizing coils are positioned and controlled to provide localized magnetic flux cancellation specifically at the end sections of the fixing roller where temperature tends to increase. This allows the heat application width in the central region to be reduced for energy saving, while simultaneously preventing excessive temperature rise at the ends through targeted demagnetizing action, thereby protecting the elastic member and protecting film from thermal damage
Solution Approach 2:
The demagnetizing coils are activated in advance to counteract the magnetic flux that would otherwise cause excessive temperature increase at the end sections. By applying this preliminary anti-action through magnetic flux cancellation, the system prevents the harmful thermal effects before they can damage the components, allowing aggressive energy-saving heat application settings in the central region without compromising component reliability
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 solution enables fine temperature control and uniform heat application across the fixing roller, improving image quality and extending the device's lifespan by preventing overheating and damage to components.
Implementation Method 1
an induction heat-applying coil is wound around a bobbin provided in a fixing roller or a heat-applying roller, and current is supplied thereto, so that over-current is generated in the heat-applying roller. As a result, the heat-applying roller is heated
Implementation Method 2
A high frequency induction heat applying apparatus including an induction heat-applying coil that receives a high frequency voltage from a high frequency power supply
Implementation Method 3
a demagnetizing coil on an exciting coil so as to cancel a magnetic flux extending from the exciting coil
Data Source
AI summary
A fixing device includes a heat applying system having an exciting coil that creates a magnetic flux for generating induction heat in a heat generation layer provided in a fixing roller. Plural demagnetizing coils are stacked in plural layers partially overlying the exciting coil to cancel the magnetic flux at one end of the fixing roller. The plural demagnetizing coils partially overlap each other.