Image Forming Apparatus Heater Waveform Control
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Solution Overview
Problem
Image forming apparatuses with single heat generating elements struggle to effectively control higher harmonics, flicker, and temperature ripple due to uniform electric current waveforms, which existing phase and wavenumber control techniques fail to adequately address.
Innovation Solution
The apparatus employs multiple heat generating groups with different resistances, each controlled by separate switch elements, with a control unit managing power distribution to create distinct electric current waveform patterns, ensuring that the waveform patterns of the heat generating groups with the smallest and second smallest resistances differ at specific phases, and that phase control periods coincide less than 50% to minimize harmonics and ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single heat generating element is used with uniform electric current waveform control, then the device complexity is reduced, but the effectiveness against higher harmonics, flicker, and temperature ripple is insufficient
Solution Approach 1:
The heater is divided into multiple heat generating groups (first, second, and third groups) with different combined resistances. Each group is controlled independently by separate switch elements, allowing different waveform patterns to be applied to each segment. This segmentation enables effective reduction of higher harmonics, flicker, and temperature ripple while maintaining manageable device complexity through modular control.
2Object-generated harmful factors
If multiple heat generating groups with different resistances are used with independent waveform control, then higher harmonics and flicker are reduced, but the device complexity increases
Solution Approach 1:
Different waveform patterns are applied to different heat generating groups based on their local characteristics (combined resistance values). The first, second, and third heat generating groups each receive tailored waveform control through their respective switch elements, optimizing harmonic reduction for each local segment while managing overall system complexity.
Solution Approach 2:
Multiple heat generating groups with different resistances are combined in parallel within the heater assembly. Their individual waveform controls are merged to collectively reduce higher harmonics and flicker effects, achieving better overall performance than a single uniformly controlled element while keeping the control architecture manageable through standardized switch element usage.
3Manufacturing precision
If phase control periods of different heat generating groups coincide extensively, then the control precision is improved, but temperature ripple increases
Solution Approach 1:
The control system employs periodic waveform patterns with different phase relationships for different heat generating groups. By carefully designing the periods and phase shifts of the waveform patterns applied to each group, the system achieves precise temperature control while preventing excessive coincidence that would cause temperature ripple. The waveform patterns are synchronized to maintain precision without creating constructive interference that increases ripple.
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 significantly reduces higher harmonics, flicker, and temperature ripple by varying the electric current waveforms across heat generating groups, optimizing heat distribution and waveform patterns to improve image fixing quality.
Implementation Method 1
a heater including at least three heat generating groups configured to generate heat by power supplied from an alternating current power source
Data Source
AI summary
A waveform pattern of an electric current running through a first heat generating group and a waveform pattern of an electric current of a second heat generating group, controlled by a control unit, in an image forming apparatus of the present invention are different from each other at at least one phase angle in one control period. The percentage of coincidence of a period of phase control of the first heat generating group and a period of phase control of the second heat generating group in the one control period is lower than or equal to 50%.