Heater Duty Ratio Control for Image Fixing
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Solution Overview
Problem
The existing duty ratio control methods for image forming apparatuses fail to accurately control the heating temperature of the fixing device's heater when the frequency of the commercial power source changes, leading to increased harmonic components and reduced resolution in power supply control, which affects the fixing of toner images on paper.
Innovation Solution
The image forming apparatus employs a control system that adjusts the duty ratio of AC power supplied to the heater based on the frequency of the commercial power source, using a zero-crossing detection circuit and duty ratio control circuit to synchronize the control cycle with the power source frequency, thereby preventing harmonic generation and ensuring precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If duty ratio control cycle is not changed when commercial power source frequency changes, then control structure remains simple, but power supply waveform collapses and harmonic components increase
Solution Approach 1:
The control cycle is made dynamic by automatically adjusting it based on the detected commercial power source frequency. The control cycle calculation unit computes the control cycle as an integer multiple of the detected AC power cycle, allowing the system to adapt to different power frequencies (50Hz or 60Hz) without manual intervention, thus maintaining reliable duty ratio control while keeping the control structure relatively simple.
Solution Approach 2:
The system changes the control cycle parameter based on the detected power frequency. By detecting the actual AC power cycle and calculating the control cycle as an integer multiple thereof, the system adjusts the control parameters to match the power source characteristics, preventing waveform collapse and harmonic generation while maintaining simple control logic.
2Ease of operation
If duty ratio control cycle is not synchronized with AC power cycle when frequency changes, then control implementation is simple, but heating temperature control resolution deteriorates
Solution Approach 1:
The system uses feedback from the detected commercial power source frequency to automatically adjust the control cycle. The control cycle calculation unit continuously monitors the AC power cycle and computes the appropriate control cycle as an integer multiple, ensuring synchronization between the duty ratio control and the power supply frequency, thereby maintaining precise heating temperature control across different power frequencies.
Solution Approach 2:
The control cycle is dynamically adjusted based on the detected power frequency to maintain synchronization. By making the control cycle adaptive rather than fixed, the system ensures that the duty ratio control remains precisely synchronized with the AC power cycle regardless of whether the frequency is 50Hz or 60Hz, preserving temperature control resolution while simplifying implementation.
3Device complexity
If fixed control cycle is used regardless of power frequency, then control logic is simple, but duty ratio control accuracy decreases
Solution Approach 1:
The control cycle parameter is changed based on the detected power frequency characteristics. The control cycle calculation unit computes the control cycle as an integer multiple of the detected AC power cycle, allowing the system to adapt its control parameters to match the actual power source frequency, thereby maintaining accurate duty ratio control without significantly complicating the control logic.
Solution Approach 2:
The system transitions from a fixed control cycle to a dynamic control cycle that automatically adjusts based on the detected power frequency. This dynamic adjustment ensures that the control logic remains relatively simple while achieving accurate duty ratio control by synchronizing the control cycle with the actual AC power cycle regardless of frequency variations.
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 allows for accurate control of the heating temperature of the fixing device, synchronizing the power supply cycle with the commercial power source frequency, ensuring consistent image fixing quality across different power frequencies and reducing electromagnetic interference.
Implementation Method 1
a zero-crossing detection circuit configured to detect a cycle of the AC power
Implementation Method 2
a heater configured to generate heat with AC power for fixing a toner image to a medium
Data Source
AI summary
An image forming apparatus includes a heater to generate heat with AC power for fixing a toner image to a medium and a power supply device to supply the AC power to the heater according to a pattern corresponding to one of at least two different combinations of a control cycle and a resolution in duty ratio. The control cycle corresponds to an integer multiple of a nominal AC power cycle. The duty ratio reflects a number of nominal AC power cycles in the control cycle during which the heater is in an on state.