Segmented Pressure Roller Charge Removal for Image Defects
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Solution Overview
Problem
The existing fixing devices in image forming apparatuses face challenges in efficiently removing electric charges from the pressure roller's core and surface layer, leading to image defects like electrostatic offset and banding images, while adding conductive fillers to the elastic layer compromises elasticity and increases device size.
Innovation Solution
A discharging brush is used to remove electric charges from both the core and surface layer of the pressure roller, which are not electrically connected, reducing the number of components and maintaining the roller's elasticity by avoiding the need for conductive fillers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive fillers are added to the elastic layer to improve electrical conductivity, then the electrical conductivity is improved, but the elasticity deteriorates and the device size increases
Solution Approach 1:
The pressure roller is divided into three distinct layers: a core layer (first layer) with conductive material, an elastic layer (second layer) with non-conductive material, and a surface layer (third layer) with conductive material. This segmentation allows each layer to perform its specialized function independently - the core and surface layers handle electrical conductivity while the elastic layer maintains elasticity without conductive fillers.
Solution Approach 2:
The elastic layer acts as an intermediary between the core layer and surface layer, electrically isolating them while maintaining mechanical contact and pressure transmission. This intermediary structure allows the roller to maintain elasticity through the elastic layer while achieving electrical conductivity through the separate conductive core and surface layers.
2Reliability
If conductive fillers are added to the elastic layer to remove electric charge from the core, then the charge removal capability is improved, but the device complexity and size increase
Solution Approach 1:
The pressure roller is segmented into three layers with the conductive surface layer (third layer) providing a direct path for charge removal from the recording medium. This eliminates the need for conductive fillers in the elastic layer and provides a more efficient charge removal mechanism at the surface where it is most needed.
Solution Approach 2:
Instead of trying to conduct electricity through the thickness of the elastic layer (radial direction), the solution provides conductivity at the surface dimension where charge removal is most effective. The conductive surface layer offers a lateral conduction path that directly contacts the recording medium, removing charges more efficiently without increasing device size.
3Stability of the object's composition
If the elastic layer is made non-conductive to maintain elasticity, then the elasticity is improved, but the electrical connection between core and surface layer is lost
Solution Approach 1:
The pressure roller is segmented into three independent layers: core layer, elastic layer, and surface layer. This segmentation allows the elastic layer to be purely elastic without conductive fillers, while the core and surface layers provide the necessary electrical conductivity independently.
Solution Approach 2:
The elastic layer serves as an electrical intermediary that physically connects the core and surface layer while maintaining electrical isolation. mechanically, it transmits pressure from the core to the surface layer, enabling the surface layer to contact the recording medium while the core provides structural support and additional conductivity pathways.
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 configuration effectively reduces the occurrence of image defects, such as electrostatic offset and banding images, while minimizing the size and cost of the fixing device by simplifying its components and maintaining the pressure roller's elasticity.
Implementation Method 1
The discharger is in contact with the first layer and the third layer and removes electric charge from the first rotator
Implementation Method 2
The heater is disposed inside a loop of the second rotator and heats the second rotator
Implementation Method 3
The elastic layer of the pressure roller is made of a non-conductive material to obtain elasticity and expansibility
Data Source
AI summary
A fixing device includes a first rotator, a second rotator, a heater, and a discharger. The first rotator includes a conductive first layer, a non-conductive second layer, and a conductive third layer. The first to third layers exist in an order of the first layer to the third layer from a center of the first rotator to an outside of the first rotator. The second rotator forms a nip between the first rotator and the second rotator. A recording medium bearing a toner image passes through the nip. The heater is disposed inside a loop of the second rotator and heats the second rotator. The discharger is in contact with the first layer and the third layer and removes electric charge from the first rotator.