Fixing Apparatus Pressure Roller Condensation Control
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Solution Overview
Problem
Film heating type fixing apparatuses in electrophotographic printers face issues with condensation slip due to moisture condensation on the pressure roller, leading to deceleration or stoppage of the fixing film, and pressure roller contamination, which causes image irregularities and paper jams, while countermeasures like air supply fans exacerbate contamination by lowering the pressure roller temperature.
Innovation Solution
A fixing apparatus with a first and second rotary member forming a nip portion, where the air supply unit supplies air during specific warm-up modes to prevent condensation slip and contamination, with control sequences based on relative humidity and print ratio to optimize air supply and warm-up periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air supply fan is used to remove water vapor from pressure roller periphery, then condensation slip is suppressed, but pressure roller contamination is generated due to lowered surface temperature
Solution Approach 1:
The patent applies preliminary action by extending the warm-up period before printing to preheat the pressure roller surface. This prevents condensation slip by ensuring the pressure roller is sufficiently heated before the fixing process begins, eliminating the need for air supply fans that would otherwise be required to remove water vapor.
Solution Approach 2:
The patent implements periodic action by controlling the air supply fan to operate only during specific periods (when condensation risk is detected based on environmental conditions) and not during others. The control unit monitors temperature and humidity to determine when air supply is necessary, thereby preventing continuous operation that would cause pressure roller contamination.
2Loss of time
If pressure roller is not sufficiently heated during warm-up, then warm-up period is short, but moisture condensation occurs on pressure roller surface causing condensation slip
Solution Approach 1:
The patent extends the warm-up period as a preliminary action to ensure the pressure roller is sufficiently heated before the fixing process begins. This preheating prevents moisture condensation on the pressure roller surface, thereby preventing condensation slip while maintaining reliable operation.
3Reliability
If air supply unit operates continuously to prevent condensation, then condensation slip is prevented, but pressure roller temperature decreases causing toner adhesion and contamination
Solution Approach 1:
The patent controls the air supply unit to operate periodically rather than continuously. The control unit monitors environmental conditions (temperature and humidity) and activates the air supply only when condensation risk is detected, thereby preventing both condensation slip and pressure roller contamination caused by continuous air supply.
Solution Approach 2:
The patent implements feedback control by using sensors to monitor temperature and humidity conditions, then using this information to control the air supply unit operation. This feedback mechanism ensures air supply is provided only when necessary to prevent condensation, avoiding unnecessary operation that would cause pressure roller contamination.
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 prevents both condensation slip and pressure roller contamination by adjusting air supply and warm-up periods according to environmental conditions, ensuring reliable image fixing without paper jams or image defects.
Implementation Method 1
a heater having a resistor heating element provided on a ceramic substrate
Implementation Method 2
a air supply unit configured to supply air to the pressure roller
Implementation Method 3
water vapor generated from the recording material is apt to be condensed
Implementation Method 4
The fixing film is rotated to follow rotation of the pressure roller by a frictional force between the outer circumferential surface of the fixing film and the surface of the pressure roller
Data Source
AI summary
The fixing apparatus includes a first rotary member that comes into contact with the unfixed toner image, a second rotary member that is heated by the first rotary member and forms the nip portion together with the first rotary member, and an air supply unit that supplies air to the second rotary member. The fixing apparatus is configured to execute a first mode of warming the first rotary member and the second rotary member as a warm-up while rotating the first rotary member and the second rotary member before the fixing process and supplying air with the air supply unit in the fixing process, and a second mode of performing the warm-up for a longer period than in the first mode and supplying air with the air supply unit in the fixing process.