Fixing Belt Heater Zoning for Small-Sheet Temperature Control
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Solution Overview
Problem
Existing image forming apparatuses face challenges in maintaining optimal fixing temperatures for varying sheet sizes, particularly when smaller sheets do not reach temperature sensors, leading to potential overheating or underheating of the fixing device.
Innovation Solution
The apparatus incorporates a first and second temperature sensor to detect temperatures of the main and sub heaters, with a cooling mechanism and controller to adjust temperatures based on sheet size, ensuring appropriate fixing temperatures are maintained by controlling the heaters and cooling fans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature sensor is used to detect the temperature of the fixing belt, then the device complexity is reduced, but the temperature control precision for different sheet sizes deteriorates
Solution Approach 1:
The temperature sensing system is segmented into multiple sensors: a first temperature sensor detects the temperature of the main heater, and a second temperature sensor detects the temperature of the sub heater. This segmentation allows independent temperature monitoring and control for different regions of the fixing belt, enabling precise temperature control for various sheet sizes without excessive system complexity.
Solution Approach 2:
Different temperature control strategies are applied to different regions of the fixing belt based on local requirements. The main heater region (central portion) and sub heater region (end portions) have separate temperature detection and control mechanisms, allowing the system to provide appropriate fixing temperatures locally for different sheet sizes and positions.
2Use of energy by moving object
If the sub heater temperature is controlled to a lower first set temperature for large sheets, then energy consumption is reduced, but the fixing temperature adequacy for smaller sheets deteriorates
Solution Approach 1:
The sub heater temperature control is made dynamic and adaptive based on sheet size detection. When a large sheet is detected (reaching the temperature detection position of the second temperature sensor), the sub heater target temperature is set to the lower first set temperature to reduce energy consumption. When a smaller sheet is detected (not reaching the detection position), the target temperature is set to the higher second set temperature to ensure adequate fixing. This dynamic adjustment resolves the contradiction between energy saving and fixing reliability.
Solution Approach 2:
The target temperature parameter of the sub heater is changed based on sheet size conditions. The system switches between two temperature sets: a lower first set temperature for large sheets and a higher second set temperature for smaller sheets. This parameter change strategy allows the system to optimize energy consumption while maintaining reliable fixing performance for different sheet sizes.
3Stability of the object's composition
If the cooling fan is operated continuously to cool the end portions of the heater, then the temperature uniformity is improved, but the energy consumption increases
Solution Approach 1:
The cooling fan operates periodically rather than continuously. It is activated when the sub heater temperature reaches or exceeds a predetermined operation start temperature, and deactivated when the temperature drops below a predetermined stop temperature. This periodic operation maintains temperature uniformity by cooling the end portions of the heater when necessary, while reducing energy consumption by avoiding continuous operation.
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 maintains appropriate fixing temperatures for both large and small sheets, preventing overheating or underheating, thereby ensuring consistent and efficient image fixation.
Implementation Method 1
The heater extends in a width direction, orthogonal to a rotation direction of the fixing belt, and heats the fixing belt
Implementation Method 2
The cooling mechanism includes a cooling fan, and cools the end portions of the heater in the width direction
Data Source
AI summary
A fixing device includes a main heater located at a central portion of a fixing belt in a direction along a rotary shaft, two sub heaters located at respective end portions, and a cooling fan that cools end portions of the heaters. When a recording sheet to undergo a fixing operation is of a size that does not reach a temperature detection position of a temperature sensor, which detects the temperature of the sub heater, a target temperature of the sub heater is set to a higher side, so that the temperature of a sheet passage region is maintained within a temperature range appropriate for the fixing operation.