Fixing Roller Temperature Control for Offset Prevention
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Solution Overview
Problem
The existing fixing apparatuses in image forming devices face challenges in maintaining the surface temperature of the fixing roller within the appropriate range, especially when switching between monochrome and color modes, leading to offset phenomena such as cold and hot offset, particularly due to the narrow common non-offset range and temperature fluctuations during warm-up and paper passing operations.
Innovation Solution
A fixing apparatus is designed with a fixing member having a heat source and an elastic layer, a pressure member creating a first nip area, and an external heating device providing a second nip area, where the temperature difference between the external heating device and the fixing member is controlled based on the nip area length to maintain the surface temperature within the non-offset range, preventing undershoot and overshoot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an external heating member is used to heat the fixing roller, then the heating speed is improved, but the temperature control precision deteriorates leading to offset phenomena
Solution Approach 1:
The heating system is divided into two independent parts: an internal heating member (halogen lamp) positioned inside the fixing roller shaft and an external heating member positioned outside the fixing roller. This segmentation allows each heating member to be controlled independently, enabling the internal member to provide base heating while the external member provides supplemental heating, thereby achieving both fast heating and precise temperature control to prevent offset phenomena
Solution Approach 2:
A temperature sensor positioned on the outer surface of the fixing roller serves as an intermediary measurement point. The temperature control device uses this sensor to detect the actual surface temperature and adjusts the external heating member accordingly. This intermediary measurement enables precise feedback control, ensuring the surface temperature remains within the appropriate range and preventing both cold and hot offset
2Productivity
If the paper transport speed is increased, then the productivity is improved, but the temperature control difficulty increases due to shorter contact time
Solution Approach 1:
The external heating member is activated in advance before the paper reaches the fixing roller to pre-heat the outer surface of the fixing roller. This preliminary heating action ensures that when the paper contacts the fixing roller at high speed, the surface is already at the appropriate temperature, compensating for the reduced contact time and maintaining effective fixing without requiring excessive temperature increases
Solution Approach 2:
The control device dynamically adjusts the operation of the external heating member based on real-time temperature sensor feedback and paper transport conditions. The heating control is made flexible and adaptive, allowing the system to respond to varying paper speeds and maintain optimal surface temperature within the appropriate range, thereby preventing both cold and hot offset under different productivity conditions
3Reliability
If the surface temperature of the fixing roller is increased to prevent cold offset, then the fixing reliability is improved, but hot offset occurs due to excessive heat transfer
Solution Approach 1:
A temperature sensor positioned on the outer surface of the fixing roller provides continuous feedback to the control device about the actual surface temperature. The control device uses this feedback to precisely regulate the external heating member, ensuring the temperature remains within the appropriate range. This feedback mechanism prevents both cold offset (by maintaining sufficient temperature) and hot offset (by preventing excessive temperature increases), thereby achieving reliable fixing without harmful effects
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 prevents toner offset by maintaining the surface temperature of the fixing member within the optimal range, ensuring high-quality image fixation without cold or hot offset issues even after warm-up, thereby improving the reliability of the image forming process.
Implementation Method 1
an external heating device which has a heat source and is disposed on the outer surface of the fixing member so that a second nip area is provided between the external heating device and the fixing member
Implementation Method 2
a halogen lamp which is disposed as a heat source inside the shaft
Data Source
AI summary
A fixing apparatus includes an external heating device which has a halogen lamp and is disposed on the outer surface of a fixing member so that a nip area is provided between the external heating device and the fixing member. A temperature difference between a surface temperature of the external heating device and a surface temperature of the fixing member is controlled in accordance with a length of the nip area in a direction of transport of the recording paper, so that the surface temperature of the fixing roller is maintained to fall within a temperature range in which offset does not occur, the offset being a phenomenon in which part of a toner formed on the recording paper sticks onto the surface of the fixing roller.