Fixing Roller Heater Control for Uniform End Temperature
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses face issues with temperature uniformity and ripples due to the use of thinned cores, leading to inefficient energy consumption and operational complexity, particularly when handling small-sized papers.
Innovation Solution
A series-parallel lighting circuit is employed for the fixing device, utilizing a flat heater and an end heater with specific duty patterns and feedback control to maintain temperature uniformity across the heating roller, including PI control for precise power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fixing roller core is thinned to reduce heat capacity, then energy consumption is reduced, but temperature uniformity deteriorates due to heat escape from support members
Solution Approach 1:
The patent applies local quality by positioning end heaters specifically at the end portions of the fixing roller to compensate for heat loss in those regions. This localized heating approach addresses the temperature non-uniformity caused by the thinned core structure without requiring uniform thickening of the entire core, thus maintaining energy efficiency while improving temperature distribution.
Solution Approach 2:
The patent changes the heating parameters by introducing separate end heaters with independent control from the main heater. This allows differential heating control where the end portions receive additional heat to compensate for support member heat escape, while the central portion maintains its heating pattern, thereby achieving temperature uniformity across the roller surface.
2Use of energy by moving object
If the fixing roller core is thinned to reduce heat capacity, then energy consumption is reduced, but temperature ripples increase due to heat escape from support members
Solution Approach 1:
The end heaters are specifically positioned at the end portions where temperature ripples occur due to support member heat escape. This localized heating stabilizes the temperature in these problematic regions without affecting the overall energy consumption of the thinned core structure.
Solution Approach 2:
The patent employs temperature detection units that monitor the temperature at the end portions of the fixing roller and provide feedback to the control unit. This feedback mechanism allows the system to dynamically adjust the end heater power to maintain stable temperature and eliminate ripples, ensuring consistent thermal conditions despite the thinned core design.
3Measurement precision
If sub heater PID temperature control is used for small-sized paper, then temperature control precision is improved, but operational complexity increases
Solution Approach 1:
The patent implements dynamic operational modes where the control unit automatically switches between different heating patterns based on paper size detection. For small-sized paper, the system activates PID control with the sub heater, while for larger paper, it uses simpler heating patterns. This dynamic adaptation provides precise temperature control when needed without permanently increasing operational complexity.
Solution Approach 2:
The heating system is segmented into main heater and sub heater with independent control capabilities. This segmentation allows the sub heater to be selectively activated for PID temperature control when handling small-sized paper, while the main heater handles other scenarios, thereby achieving precision control only when necessary and reducing overall operational complexity.
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 ensures uniform temperature distribution and reduces energy consumption by minimizing temperature ripples and operational complexity, enhancing the fixing process efficiency.
Implementation Method 1
The heaters are halogen lamps, for example
Implementation Method 2
the heat escapes from support members supporting the both end portions of the fixing roller
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
AI summary
To reduce a load of lighting control and control the temperature of a fixing roller to be kept uniform. When a warm-up operation is started by power-on of an image forming apparatus (S10), a control unit set a series lighting mode (S11) . After lapse of a predetermined period of time, the control unit switches the lighting mode to a parallel lighting mode (S12). After that, when the measured temperature of end portions of a heating roller is equal to or lower than a reference temperature, the control unit sets the lighting mode to an end heat up mode (S16), and subjects an end heater to full-lighting control and subjects a flat heater to lighting control in a duty pattern at a duty ratio between 33. 33% and 80% (S17). Meanwhile, when the measured temperature of the end portions of the heating roller exceeds the reference temperature, the control unit sets the lighting mode to a flat mode (S18), and subjects the flat heater to full-lighting control and subjects the end heater to lighting control in a duty pattern at a duty ratio between 33.33% and 80% (S19).