Segmented Fixing Heater for Uneven Thermal Stress
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Solution Overview
Problem
Existing image forming apparatuses face issues with heat energy wastage in non-image areas, leading to temperature differences and thermal stress, which cause conveyance errors and image quality degradation due to uneven heating of the fixing rotary body and opposed member.
Innovation Solution
A fixing device with a heater having multiple heat generators arranged in the width direction of the recording medium, where power is controlled to maintain higher temperatures for image areas and lower temperatures for non-image areas, with adjacent non-image area heat generators receiving varying power levels to minimize heat waste and thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heating member heats the fixing rotary body over an entire width of the sheet, then the entire sheet is heated uniformly, but heat energy is wasted in non-image areas
Solution Approach 1:
The heating member is divided into multiple heat generators (first heat generator for image area, second heat generators for non-image areas) that can be independently controlled. This segmentation allows selective heating of only the image area at high temperature while maintaining lower temperature in non-image areas, eliminating energy waste without compromising uniform heating where needed.
Solution Approach 2:
Different regions of the fixing rotary body are assigned different heating characteristics: the image area receives high temperature heating for effective toner fusion, while non-image areas receive reduced heating to minimize energy consumption. This local differentiation resolves the contradiction between uniform heating requirements and energy waste prevention.
2Loss of energy
If different power is supplied to adjacent heat generators in non-image areas, then heat waste is reduced, but temperature difference causes thermal expansion variation
Solution Approach 1:
The patent dynamically adjusts the power supply parameters to heat generators based on real-time temperature feedback. When temperature differences exceed a predetermined threshold, the control unit modifies power distribution to adjacent heat generators to compensate for thermal expansion variations, maintaining stable dimensional characteristics while preserving energy efficiency.
Solution Approach 2:
Temperature detection units continuously monitor the temperature distribution across the fixing rotary body, and the control unit uses this feedback information to adjust power supply to heat generators. This closed-loop control ensures that thermal expansion remains within acceptable limits while maximizing energy savings in non-image areas.
3Loss of energy
If temperature difference occurs in the fixing rotary body, then heat energy is saved in non-image areas, but thermal stress causes deformation and kink
Solution Approach 1:
The heating system transitions from static uniform heating to dynamic selective heating, where power distribution to heat generators is continuously adjusted based on operational conditions. This dynamic control allows the system to optimize energy savings while maintaining thermal stability through real-time power modulation that compensates for thermal stress and prevents deformation.
Solution Approach 2:
The control unit predicts potential thermal stress conditions by monitoring temperature distribution trends and proactively adjusts power supply to prevent excessive temperature differences. This preventive approach cushions against thermal stress before it causes deformation or kink, ensuring fixing belt reliability while maintaining energy efficiency.
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 reduces heat energy consumption in non-image areas, prevents deformation of the fixing belt and pressure roller, and enhances image quality by maintaining consistent conveyance speed and reducing wrinkles.
Implementation Method 1
a heater to heat the fixing rotary body. The heater includes plural heat generators arranged in a width direction of a recording medium and separately supplied with power
Implementation Method 2
The fixing rotary body and the opposed member contact each other to form a nipping portion. When a sheet having a toner image passes through the nipping portion, toner is fused under the heat of the fixing rotary body
Data Source
AI summary
A fixing device includes a fixing rotary body, an opposed member opposing the fixing rotary body to form a nipping portion, and a heater to heat the fixing rotary body. The heater includes heat generators arranged in a width direction of a recording medium and separately supplied with power. When an unfixed image on the medium has an image area and a non-image area, power supplied to each of the heat generators is controlled so that, of the heat generators, a first heat generator corresponding to the image area becomes a higher temperature and second heat generators corresponding to the non-image area becomes a lower temperature. When the second heat generators are adjacent to each other, power supplied to one of the second heat generators closer to the image area is set to be greater than power supplied to another of the second heat generators farther from the image area.