Heating Device Conductor Spacing to Reduce Conductor Heat Rise
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Solution Overview
Problem
Existing fixing devices in image forming apparatuses experience uneven temperature distribution in heaters due to regions facing non-sheet passing areas accumulating heat, leading to higher temperatures and potential conductor temperature rise, which is not addressed by prior solutions.
Innovation Solution
A heating device with a pair of rotators forming a nip, a flexible conductor coupled to a temperature sensor, and a conductor support that maintains a larger distance from the heater in high-temperature regions, reducing direct contact and heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conductor is disposed in the vicinity of the heater to enable temperature sensing, then the temperature control function is achieved, but the conductor temperature rises due to heat transmission from the heater
Solution Approach 1:
A support protrusion is introduced as an intermediary structure between the heater and the conductor. This protrusion supports the conductor at a position away from the heater surface, reducing direct heat transmission while maintaining the conductor's proximity for effective temperature sensing. The support protrusion acts as a thermal barrier that allows functional closeness while preventing harmful thermal coupling.
Solution Approach 2:
The solution moves the conductor positioning from a two-dimensional plane close to the heater surface into a three-dimensional configuration by utilizing the vertical dimension. The support protrusion elevates the conductor above the heater surface, creating a spatial separation that reduces heat transmission while maintaining sensing capability. This dimensional transition allows the conductor to be both close enough for sensing and far enough to avoid excessive heating.
2Productivity
If sheets continuously pass through the fixing device, then productivity is improved, but uneven temperature distribution occurs in the heater with heat accumulation in non-sheet passing regions
Solution Approach 1:
The support protrusion is strategically positioned to provide localized support to the conductor in regions where heat accumulation is likely to occur during continuous sheet processing. This localized structural modification addresses the uneven temperature distribution by ensuring the conductor maintains appropriate spacing from high-temperature zones, particularly in non-sheet passing regions where heat buildup is problematic.
3Temperature
If material with heat resistance is used for the conductor or its covering, then the conductor can withstand high temperatures, but manufacturing cost increases
Solution Approach 1:
The support protrusion serves as a thermal intermediary that reduces the thermal load on the conductor. By positioning the conductor away from the heater surface through this protrusion, the maximum temperature experienced by the conductor is reduced, allowing the use of less expensive materials with lower heat resistance requirements while still maintaining reliable 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
The solution effectively reduces conductor temperature rise in high-temperature regions, ensuring uniform heat distribution and preventing overheating, thus maintaining efficient operation of the fixing device.
Implementation Method 1
a heater (23) that heats at least one of the pair of rotators
Implementation Method 2
The temperature sensor is coupled to a controller via a conductor such as a lead wire
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
A heating device (20, 83) includes a pair of rotators (21 and 22, 71 and 72) in contact with each other to form a nip through which a sheet passes, a heater (23) heating at least one of the pair of rotators (21 and 22, 71 and 72), a temperature sensor (27) detecting a temperature of the heater (23), a conductor (44), a conductor support (30), and a component (24, 50, 70, 87) supporting the conductor support (30). The conductor (44) has flexibility and coupled to the temperature sensor (27). The conductor support (30) supports the conductor (44) such that a distance from the conductor (44) to at least one position of the heater (23) outside a predetermined region of the heater (23) in a width direction of the sheet is larger than a distance from the conductor (44) to a position of the heater (23) inside the predetermined region.