Fixing Device Thermal Expansion Control for Sheet Wrinkling
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Solution Overview
Problem
Image forming apparatuses with fixing devices face challenges in preventing sheet wrinkling due to inconsistent heating roller temperature control, leading to excessive heat transmission and thermal expansion, especially when the pressure roller's elastic layer is hard and requires longer time for adequate thermal expansion.
Innovation Solution
The apparatus includes a conveying device, a fixing device with a heater and temperature sensor, and a controller that determines the optimal timing for sheet conveyance based on temperature gradients and the accumulated usage of the fixing device, delaying sheet pickup when the pressure roller is new to ensure adequate thermal expansion and prevent wrinkling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the heating roller is heated to reach target temperature quickly, then the productivity is improved, but the sheet may get wrinkled due to excessive heat transmission
Solution Approach 1:
The system performs preliminary heating of the heating roller before sheet conveyance begins. The controller monitors the temperature of the heating roller and only starts sheet conveyance after the roller reaches the predetermined temperature threshold, ensuring the roller is properly prepared to prevent wrinkling while maintaining efficient operation.
Solution Approach 2:
The temperature sensor continuously monitors the heating roller temperature and provides feedback to the controller. Based on this feedback, the controller dynamically adjusts the heating control and sheet conveyance timing, creating a closed-loop system that prevents both excessive heating and wrinkling while optimizing productivity.
2Device complexity
If the pressure roller is used in new condition with hard elastic layer, then the device complexity is reduced, but the thermal expansion is insufficient causing delayed wrinkle prevention
Solution Approach 1:
The system changes the operational parameters by monitoring temperature and using feedback control to compensate for the hard elastic layer's slow thermal expansion. The controller adjusts the heating profile and sheet conveyance timing based on actual temperature readings, ensuring adequate pressure development time without complicating the pressure roller structure.
3Productivity
If the sheet is conveyed earlier before temperature stabilization, then the productivity is improved, but the heating roller may be excessively heated causing thermal expansion and wrinkling
Solution Approach 1:
The temperature sensor provides real-time feedback on heating roller temperature to the controller. The controller uses this feedback to determine the optimal moment to start sheet conveyance, preventing both premature conveyance (which causes wrinkling) and delayed conveyance (which reduces productivity).
Solution Approach 2:
The system performs preliminary temperature monitoring and stabilization before initiating sheet conveyance. The controller ensures the heating roller reaches the appropriate temperature threshold and stabilizes before sheets are introduced, preventing excessive heating while maintaining efficient workflow.
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 inhibits sheet wrinkling by ensuring the pressure roller is adequately thermally expanded before the sheet reaches the fixing device, maintaining a stable conveying state and reducing the likelihood of thermal expansion-induced wrinkling.
Implementation Method 1
The fixing device includes a heater... configured to thermally fix developer on the sheet conveyed by the conveying device
Implementation Method 2
The temperature sensor is configured to sense a temperature of the nip portion and output a temperature signal indicating the sensed temperature
Implementation Method 3
a pressure roller which is a pressurizing-side rotating member is thermally expanded with an increase in the temperature of the heating roller, so as to be deformed into an appropriate shape
Data Source
AI summary
An image forming apparatus includes a conveying device; a fixing device; and a controller. The controller is configured to perform: in response to determining that a first condition is met, starting sheet conveyance by the sheet conveying device upon expiration of a first predetermined period of time starting from receipt of a print instruction; and in response to determining that a second condition different from the first condition is met, starting sheet conveyance by the sheet conveying device at selective one of a first timing and a second timing. The second timing is selected upon determination that an accumulated amount of usage of the fixing device is not greater than a predetermined amount. The first timing is a timing at which a sensed temperature has reached a first threshold value. The second timing is a timing at which a second predetermine period of time has expired after the first timing.