Dual Heater Fixing Unit Inrush Current Control
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Solution Overview
Problem
Existing image forming apparatuses using halogen heaters experience flicker phenomena due to inrush current, which affects AC power source voltage stability, and are challenged by varying commercial AC power voltages, leading to inefficient heating and insufficient flicker reduction.
Innovation Solution
An image forming apparatus utilizing two commercial power sources with separate heaters and switches, controlled by a CPU to adjust duty cycles based on detected AC voltages, ensuring efficient heating and reduced flicker by managing inrush current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the energization angle or start-up period is fixed to match high effective value AC voltage, then heating efficiency is improved, but flicker reduction becomes insufficient when low effective value voltage is applied
Solution Approach 1:
The patent applies dynamics by making the energization angle and start-up period variable rather than fixed. The control unit dynamically adjusts these parameters based on the detected AC voltage effective value, allowing the system to adapt to different voltage conditions while maintaining optimal heating efficiency and flicker reduction performance.
Solution Approach 2:
The patent changes the parameters of energization angle and start-up period based on the detected AC voltage effective value. By modifying these control parameters according to voltage conditions, the system achieves both efficient heating and effective flicker reduction across varying power source conditions.
2Object-affected harmful factors
If inrush current is reduced during heater start-up, then flicker phenomenon is reduced, but heating time increases
Solution Approach 1:
The patent applies periodic action by implementing a start-up period during which the energization angle is gradually increased. This staged, periodic approach to energization reduces inrush current and flicker while ultimately achieving the required heating temperature, balancing flicker reduction with acceptable heating time.
Solution Approach 2:
The patent applies preliminary action by implementing a start-up period before normal operation, during which the energization angle is gradually increased from a lower initial value. This preliminary controlled energization reduces flicker and inrush current before the heater reaches full power, preventing harmful voltage fluctuations.
3Reliability
If multiple heaters are supplied from multiple commercial power sources, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the power supply system into multiple independent branches, each with its own heater and commercial power source. The control unit manages each branch separately, detecting voltage from one power source and controlling both heaters independently, which improves reliability while managing complexity through modular organization.
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 solution effectively maintains target temperature for fixing images while reducing flicker and inrush current, even with varying AC power voltages, by dynamically controlling heater duty cycles.
Implementation Method 1
a first heater to which a first current is supplied from a first commercial power source to generate heat; a second heater to which a second current is supplied from a second commercial power source to generate heat
Data Source
AI summary
A controller obtains a first duty cycle of a first current to be supplied to a first heater and a second duty cycle of a second current to be supplied to a second heater and controls the first switch and the second switch after the reduction control period, such that the temperature of a fixing unit maintains a target temperature for fixing the image by the fixing unit.