Fixing Device Nip Pressure Control for Jam Handling
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Solution Overview
Problem
In image-forming apparatuses with fixing devices, sheets can become jammed and either get wrapped around rotating rollers or cause wear due to improper switching of the heating body's position relative to the pressure roller, leading to damage or jamming issues.
Innovation Solution
An image-forming apparatus with a controller that manages the switching of the heating body's position and nip pressure, reducing pressure before halting rotation when a jam occurs to prevent sheet wrapping and wear, and adjusting pressure settings based on the presence of a sheet in the nip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the position of the heating body is switched from the pressure contact position to the separated position after halting rotation of the pressure roller, then the belt wear is reduced, but the sheet may become wrapped around the rotating pressure roller
Solution Approach 1:
The controller switches the heating body from the pressure contact position to the separated position before halting the pressure roller rotation. This preliminary action reduces the nip pressure while the roller is still rotating, preventing sheet wrapping, and then stops the rotation. This sequence resolves the contradiction by performing the position switch in advance to avoid both belt wear and sheet wrapping.
2Object-affected harmful factors
If the position of the heating body is switched from the pressure contact position to the separated position before halting rotation of the pressure roller, then sheet wrapping is prevented, but the belt may become worn and incur damage
Solution Approach 1:
The controller switches the heating body position before halting the pressure roller, performing the protective action in advance. By reducing nip pressure while the roller is still rotating, the sheet wrapping is prevented, and the controlled sequence ensures belt durability is maintained through proper timing of the position switch relative to the rotation halt.
3Strength
If the nip pressure is maintained at the first nip pressure during sheet jam, then the sheet is securely held, but the sheet may become wrapped around the rotating pressure roller
Solution Approach 1:
The controller dynamically adjusts the nip pressure by switching the heating body from the pressure contact position to the separated position, changing the pressure from the first nip pressure to a reduced pressure state. This dynamic adjustment prevents sheet wrapping while maintaining adequate holding force during the critical transition period before the pressure roller halts rotation.
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
Prevents sheet wrapping around rollers and reduces wear on the belt by controlling the nip pressure and rotation halting sequence during jams, enhancing operational safety and device longevity.
Implementation Method 1
The heater is configured to heat the first fixing member
Implementation Method 2
The pressure modifying mechanism is configured to modify a nip pressure at the nip to one of a first nip pressure and a second nip pressure smaller than the first nip pressure
Implementation Method 3
The first fixing member is configured to rotate. The motor is configured to drive the first fixing member
Data Source
AI summary
In an image-forming apparatus, a fixing device includes: a first fixing member; a heater; a motor; a second fixing member; and a pressure modifying mechanism. The second fixing member forms a nip together with the first fixing member. The pressure modifying mechanism modifies a nip pressure at a nip to one of a first nip pressure and a second nip pressure smaller than the first nip pressure. In a first case where a sheet jam occurs in the image-forming apparatus and no sheet exists in the nip, a controller performs: reducing the nip pressure from the first nip pressure to the second nip pressure; and halting rotation of the first fixing member after completed the reducing. In a second case where a sheet jam occurs in the image-forming apparatus and a sheet exists in the nip, the controller performs: the halting; and the reducing after completed the halting.