Fixing Device Power Control for Uniform Gloss
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Solution Overview
Problem
Electromagnetic induction heating type fixing devices with magnetic shunt alloys experience uneven fixing and gloss due to temperature fluctuations in non-sheet passing regions, leading to reduced fixity and glossiness on recording sheets.
Innovation Solution
A fixing device with a magnetic shunt alloy and a power control system that adjusts the power supplied to the excitation coil based on detected temperatures, switching to a fixed control frequency before the non-sheet passing region reaches the Curie temperature to maintain a stable power output and prevent temperature drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a magnetic shunt alloy is used to prevent excessive temperature rise in non-sheet passing regions, then the temperature control of the fixing member is improved, but uneven fixing and uneven gloss occur when the magnetic shunt alloy reaches the Curie temperature
Solution Approach 1:
The patent applies preliminary action by detecting the temperature of the non-sheet passing region and determining when it is approaching the Curie temperature before actually reaching it. The power control unit then proactively adjusts the power supply to the excitation coil in advance, preventing the magnetic shunt alloy from reaching the Curie temperature where permeability suddenly changes. This anticipatory control avoids the harmful effects of reaching the critical temperature point.
Solution Approach 2:
The patent implements feedback control by continuously detecting the temperature of the non-sheet passing region and using this information to adjust the power supply to the excitation coil. The power control unit receives temperature feedback and dynamically modifies the power level to maintain the magnetic shunt alloy temperature below the Curie temperature, thereby preventing sudden permeability changes and ensuring uniform fixing and gloss across the sheet.
2Temperature
If feedback control is used to maintain power supply based on sheet passing region temperature, then the fixing temperature is maintained, but temperature fluctuations occur when the magnetic shunt alloy reaches Curie temperature causing uneven fixing
Solution Approach 1:
The patent introduces an intermediary control mechanism by adding a determiner that monitors the non-sheet passing region temperature and a power control unit that acts as an intermediary between the temperature detection and the excitation coil power supply. This intermediary layer prevents direct feedback control based solely on sheet passing region temperature from causing instability when the magnetic shunt alloy approaches Curie temperature, by proactively adjusting power before the critical transition occurs.
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 effectively suppresses temperature variations in the fixing belt, preventing uneven fixing and gloss across the recording sheet, thereby enhancing the consistency and quality of the fixing process.
Implementation Method 1
an excitation coil supplied with power and generating an alternating magnetic field
Implementation Method 2
When the temperature of the heat generating element in the non-sheet passing regions rises to the Curie temperature, the heat generating element transitions from being ferromagnetic to being paramagnetic. The magnetic flux density flowing through this portion suddenly decreases
Implementation Method 3
high-frequency current is passed through an excitation coil to produce an alternating magnetic field, thus producing an eddy current in the heating layer of the fixing member, which is in the shape of a belt, resulting in Joule heating
Data Source
AI summary
A fixing device includes an excitation coil, a fixing member heated by electromagnetic induction by the excitation coil, a magnetic shunt alloy member, a Curie temperature of which is higher than a target fixing temperature, a determiner that determines whether the temperature of a non-sheet passing region of the fixing member is about to reach the Curie temperature, and a power controller that controls power supplied to the excitation coil. Until the determiner determines that the Curie temperature is about to be reached, the power controller performs feedback control to provide power to the excitation coil. When the determiner determines that the Curie temperature is about to be reached, the power controller switches to fixed power control so that a difference between power supplied when the Curie temperature is about to be reached and power supplied after reaching the Curie temperature falls within an allowable range.