Fuser Temperature Droop Control via High Power Preheating
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Solution Overview
Problem
In electrophotographic image forming apparatuses, halogen lamp fusers experience significant temperature droop at the beginning of a print job due to their high thermal mass, leading to poor image quality and potential structural failures from temperature overshoot, as the temperature sensor detects a drop in temperature with a delay, causing extended power application and heating above the target temperature.
Innovation Solution
A method is implemented to control the fuser assembly by determining a set point temperature and switching the power control to a high power region if the sensed temperature is below a heating temperature threshold, or if a predetermined time has elapsed, to rapidly heat the fuser and minimize temperature droop and overshoot, using a dual pulse width modulation control to manage power efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the halogen lamp fuser uses a hot roller with high thermal mass, then the fuser can maintain stable temperature during operation, but the temperature sensor detects temperature drops with delay causing temperature droop at the beginning of print jobs
Solution Approach 1:
The system performs preliminary heating by detecting the transition to print mode and applying high power to the halogen lamp before the temperature droop actually occurs. This anticipatory action ensures the hot roller is pre-heated and ready to maintain stable temperature when printing begins, eliminating the delay caused by thermal mass.
Solution Approach 2:
The control system dynamically adjusts the power level to the halogen lamp based on operational conditions. During standby mode, normal temperature control is used, but upon detecting print mode transition, the system switches to high power mode temporarily. This dynamic adjustment allows the system to overcome the inherent delay caused by thermal mass while maintaining stability during normal operation.
2Temperature
If the halogen lamp provides continuous power to compensate for temperature droop, then the temperature can be maintained, but the extended power application causes temperature overshoot heating the hot roller above target temperature
Solution Approach 1:
The system uses periodic monitoring of temperature sensor readings to determine when to apply high power and when to return to normal control. By continuously monitoring and periodically adjusting power based on detected temperature conditions, the system maintains temperature without causing overshoot, as it can detect when the target temperature is reached and adjust accordingly.
Solution Approach 2:
The control system uses feedback from the temperature sensor to regulate power application to the halogen lamp. When the sensor detects that the target temperature has been reached or exceeded, the system reduces or stops high power application, preventing temperature overshoot. This closed-loop feedback mechanism ensures temperature is maintained at the target level without harmful overheating.
3Loss of energy
If the fuser operates in standby mode for extended periods, then energy consumption is reduced, but the hot roller temperature drops requiring extended heating time when print mode resumes
Solution Approach 1:
When the system transitions from standby mode to print mode, it performs preliminary high-power heating to quickly restore the hot roller temperature. This anticipatory heating action occurs immediately upon detecting print mode resumption, minimizing the time required to reach operational temperature and reducing the impact of extended standby periods.
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 approach effectively minimizes temperature droop and overshoot, maintaining consistent image quality by ensuring the fuser reaches and maintains the target temperature quickly, reducing the risk of structural failures and improving the quality of printed images.
Implementation Method 1
A hot roller may comprise a metal core with a conductive rubber coating surrounded by a PFA or PTFE sleeve and a halogen lamp located inside the metal core
Implementation Method 2
heat energy traveling from the interior of the hot roller may take 5 to 10 seconds to reach the outer surface of the hot roller
Implementation Method 3
The hot roller may rotate against the backup roller causing an initial transfer of heat energy from the hot roller to the backup roller
Data Source
AI summary
A method of controlling a fuser assembly within an image forming apparatus having a fuser assembly including a heating member and a backup member cooperating with the heating member to form a nip therebetween for fusing images onto substrates passing through the nip. The method is provided to minimize or avoid a temperature droop condition of the fuser and includes the steps of determining a set point temperature for performing a fusing operation, and determining whether the image forming apparatus has transitioned from a standby mode to a print mode upon receipt of a print job. If a sensed temperature of the fuser is within a temperature range having an upper threshold temperature that is less than the heating temperature and greater than the set point temperature or a lower threshold temperature, a power control for the fuser is switched to operate in a high power region, increasing power to the fuser, to provide heat energy to the heating member.