Dual Heater Fixing Unit Standby Flicker Control
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Solution Overview
Problem
Electrophotographic image forming apparatuses face challenges in controlling heater temperatures to prevent flicker phenomena during standby mode, which affects the fixability of toner images and increases long-time flicker values due to frequent on/off switching of high-power heaters.
Innovation Solution
The apparatus employs two heaters with different heat generation distribution characteristics, powered by separate commercial power sources, and a controller that alternates their operation to maintain a standby temperature without overlapping power supply periods, thereby reducing flicker and improving temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heater is turned on/off repeatedly at high frequency during standby mode to maintain standby temperature, then the time to reach target fixing temperature is reduced, but the long-time flicker value increases
Solution Approach 1:
The single heater is segmented into two separate heaters (first heater and second heater) powered by different commercial power sources. This segmentation allows independent control of each heater, enabling the system to alternate between them during standby mode to maintain temperature while reducing flicker effects on a single power line.
Solution Approach 2:
The controller implements periodic action by alternately switching the first and second heaters on and off during standby mode. Instead of continuously switching one heater at high frequency, the system periodically activates each heater in sequence, maintaining the standby temperature while distributing the switching events across different time periods to reduce flicker.
2Productivity
If a single high-power heater is used for heating, then the heating efficiency is high, but the flicker phenomenon occurs when the heater is turned on/off
Solution Approach 1:
The single high-power heater is divided into two separate heaters (first heater and second heater), each connected to different commercial power sources. This segmentation maintains the high heating capability of the system while distributing the power consumption across two separate power lines, thereby reducing the flicker phenomenon on each individual power line.
Solution Approach 2:
The system merges two heating functions into a single integrated heating system. Both the first heater and second heater work together to provide the necessary heating power, combining their capabilities to maintain high heating efficiency while mitigating the flicker effect through coordinated operation and separate power sources.
3Loss of time
If the heater temperature is maintained at standby temperature during standby mode, then the time required to heat to target temperature is shortened, but the heater must be turned on/off frequently which exacerbates flicker
Solution Approach 1:
The heating system is segmented into two independently controllable heaters during standby mode. This allows the controller to manage the on/off switching of each heater separately, reducing the frequency of switching events on any single power line while still maintaining the standby temperature through coordinated operation.
Solution Approach 2:
The controller employs periodic action by alternately activating the first and second heaters during standby mode. Instead of maintaining continuous high-frequency switching of a single heater, the system uses periodic, lower-frequency switching of each heater in sequence, achieving the same temperature maintenance goal with reduced flicker impact.
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 effectively reduces long-time flicker and shortens the time to reach target temperatures by alternating the operation of heaters with distinct heat generation profiles, enhancing the fixability of toner images and reducing power consumption during standby.
Implementation Method 1
a first heater to which a first current is supplied from a first commercial power source to generate heat
Implementation Method 2
a second heater to which a second current is supplied from a second commercial power source different from the first commercial power source to generate heat
Data Source
AI summary
A fixing unit includes a first heater, a first switch, a second heater, and a second switch. In an image forming mode, a controller controls the first switch and the second switch to keep a temperature of the fixing unit at a fixing temperature serving as a target temperature for fixing the image on the sheet. In a standby mode, the controller controls the first and second switches to keep the temperature of the fixing unit at a standby temperature, and controls the first and second switches such that a period in which a first current is supplied to the first heater and a period in which a second current is supplied to the second heater do not overlap.