Induction Heating Coil Temperature Control via Pulse Modulation
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Solution Overview
Problem
Conventional image heating apparatuses based on electromagnetic induction are complex in structure due to the need for precise control of temperature and heat generation patterns along the lengthwise direction of rotational members, making them cumbersome for controlling temperature and heat distribution.
Innovation Solution
An image heating apparatus with a cylindrical rotatable member, an opposing member, a nip forming member, a magnetic field generating device, a converter, and a controller, where the rotatable member has an electroconductive layer and an excitation coil generating an alternating magnetic field, and a high frequency converter applying controlled voltage to manage temperature and heat generation patterns through adjustable pulse and burst durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electromagnetic induction heating apparatus control methods are used, then temperature control and heat generation pattern control are achieved, but the structure becomes complicated
Solution Approach 1:
The patent applies parameter changes by controlling the pulse width and frequency of the high frequency voltage supplied to the excitation coil. By adjusting these electrical parameters, the system achieves precise control over the temperature and heat generation pattern along the rotational member without adding complex mechanical or structural control mechanisms. This resolves the contradiction by maintaining manufacturing precision through electrical parameter modulation rather than structural complexity.
2Manufacturing precision
If conventional electromagnetic induction heating apparatus control methods are used, then heat generation pattern control is achieved, but the structure becomes complicated
Solution Approach 1:
The patent controls the heat generation pattern by varying the pulse width and frequency parameters of the high frequency voltage applied to different sections of the excitation coil. This electrical parameter control method achieves precise heat generation pattern control along the lengthwise direction of the rotational member while keeping the overall device structure simple, thereby resolving the contradiction between manufacturing precision and device complexity.
3Reliability
If multiple high frequency converters are used for temperature control, then temperature control capability is improved, but the device complexity increases
Solution Approach 1:
The patent makes a single high frequency converter multi-functional by enabling it to control both temperature and heat generation pattern through parameter modulation (pulse width and frequency). This single converter can adjust its output characteristics to achieve different heating zones and temperature levels, eliminating the need for multiple dedicated converters while maintaining temperature control capability and improving system reliability.
Solution Approach 2:
The patent introduces dynamic control capabilities to a single high frequency converter by enabling real-time adjustment of pulse width and frequency parameters. This dynamic parameter modulation allows the converter to adaptively control temperature and heat distribution patterns, providing the functionality of multiple converters through one dynamically adjustable unit, thus reducing device complexity while maintaining control capability.
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 apparatus simplifies the structure while effectively controlling the temperature and heat generation pattern along the lengthwise direction of the rotational member, ensuring proper heat distribution for image fixation, matching the size of the recording medium.
Implementation Method 1
The magnetic field generating device produces an induced current in a circumferential direction of the rotatable member by supplying an AC current to the excitation coil
Implementation Method 2
The present invention relates to an image heating apparatus that employs a heating method based on electromagnetic induction
Data Source
AI summary
An image heating apparatus includes an electroconductive cylindrical member, an opposing member thereto, a nip forming member cooperating with the opposing member to form a nip configured to nip and feed a recording material, a magnetic field generating device, a converter, a temperature detector for the rotatable member, and a converter controller. The magnetic field generating device includes an excitation coil in an inside space of the rotatable member so that a helicity axis of the excitation coil is in parallel with an axial direction of the rotatable member to produce an induced current in a circumferential direction of the rotatable member. The converter applies a high frequency voltage to the coil. The controller controls the temperature of the rotatable member by controlling at least one of a pulse period, a pulse-on time, a burst period, and a burst-on time.