Fusing Heater Control Switching Pulse Modulation Phase Control
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Solution Overview
Problem
Image forming apparatuses face an increase in warm-up time due to the limitation of power allocation to the fusing heater when optional apparatuses are added, as the duty ratio must be kept below 70% to prevent noise generation, resulting in underutilization of the available power.
Innovation Solution
An image forming apparatus that switches between pulse modulation and phase control methods to allocate the maximum power to the fusing heater without exceeding its rated power, using a hardware processor to calculate and adjust the duty ratio based on the available power and the power requirements of other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the duty ratio is set to 70% or lower to prevent noise generation, then noise is suppressed, but the power allocation to the fusing heater is reduced and warm-up time increases
Solution Approach 1:
The system dynamically switches between PWM method and phase control method based on the calculated duty ratio. When the duty ratio exceeds the predetermined threshold, the system transitions from PWM to phase control, enabling flexible adaptation to different power allocation scenarios while preventing noise generation.
Solution Approach 2:
The invention changes the control parameter from duty ratio (PWM) to phase angle (phase control) to resolve the contradiction. By calculating the required duty ratio and comparing it with the threshold, the system selects the appropriate control method, thereby optimizing both noise suppression and warm-up performance.
2Adaptability or versatility
If optional apparatuses are added to the image forming apparatus, then functionality is enhanced, but the available power for the fusing heater decreases due to power limit constraints
Solution Approach 1:
The system calculates the required duty ratio based on the power consumption of optional apparatuses and provides feedback to the control unit. This feedback mechanism enables the system to adjust the power allocation to the fusing heater dynamically, ensuring optimal performance while respecting the upper power limit.
Solution Approach 2:
The power allocation system is made dynamic by continuously monitoring the power consumption of optional apparatuses and adjusting the duty ratio or switching to phase control accordingly. This dynamic adjustment allows the system to accommodate additional functionality while maintaining adequate power for the fusing heater.
3Loss of time
If the duty ratio is increased to reduce warm-up time, then warm-up performance is improved, but noise generation occurs due to recovery current in the freewheel diode
Solution Approach 1:
The control unit acts as an intermediary that calculates the required duty ratio and determines the appropriate control method. By introducing this intermediary calculation step, the system can predict potential noise generation and switch to phase control before noise occurs, thereby maintaining both performance and noise suppression.
Solution Approach 2:
The system performs preliminary calculation of the duty ratio before actual power supply. By comparing the calculated duty ratio with the predetermined threshold in advance, the system can preemptively switch to phase control method to prevent noise generation, rather than reacting after noise 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 approach allows for the maximization of power allocation to the fusing heater, reducing the warm-up time and ensuring that the power is utilized efficiently without generating noise.
Implementation Method 1
one of the devices has a heater as an electric element and fuses a toner image onto a sheet with a fusing member heated by the heater
Data Source
AI summary
An image forming apparatus: acquires, before start of current supply to electric elements including heater, information indicating rated power of the heater and total consumption power of the electric elements excluding the heater; subtracts the total consumption power from upper power limit of the apparatus, and calculates maximum power not exceeding the rated power and remaining power thus subtracted; obtains duty ratio based on assumption of current supply corresponding to the maximum power according to pulse modulation, and determines whether the duty ratio falls within predetermined range; and controls, when the duty ratio falls within the range, drive circuit to supply alternating current by pulse modulation method, and when the duty ratio falls outside the range, to supply the alternating current by phase control method that temporarily interrupts the supply of the alternating current to the heater in half cycles of the alternating current.