Fusing Unit Static Discharge via Brush and Grounded Roller
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face issues with image loss and contamination due to static electricity during the fusing process, where static charges cause toner detachment and scattering, leading to image defects and contamination of the apparatus and print medium.
Innovation Solution
A fusing unit with a non-power source discharging configuration is introduced, featuring a discharging member located near the fusing nip, a non-conductive fluoropolymer release layer, and a conductive pressure roller with controlled surface resistance, which manages static electricity and prevents image loss by grounding the heating member and pressure roller, while a discharging brush efficiently discharges static from the print medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a discharging plate is used to apply voltage to the print medium before fusing, then static electricity is reduced, but toner image adherence decreases and blur or scattering occurs
Solution Approach 1:
The invention extracts the harmful static electricity from the print medium by introducing a discharging member that selectively removes static charges without affecting the toner image. The discharging member is positioned to contact only the rear surface of the print medium, extracting static electricity while leaving the front surface with intact toner image.
Solution Approach 2:
The invention applies local quality by differentiating the treatment of different surfaces of the print medium. The discharging member is designed to discharge static electricity only from the rear surface while maintaining the front surface's properties for toner image adherence. This localized approach ensures that static discharge does not affect the toner image quality.
2Manufacturing precision
If voltage is applied to the pressure roller to prevent image loss, then toner image adherence increases, but the pressure roller surface becomes charged and contaminated by toner or paper dust
Solution Approach 1:
The invention extracts static electricity from the print medium using a discharging member, eliminating the need to apply voltage to the pressure roller. This extraction approach prevents the pressure roller surface from becoming charged and contaminated, while still maintaining toner image adherence through proper static control.
Solution Approach 2:
The discharging member acts as an intermediary between the print medium and the environment, providing a controlled path for static electricity discharge. This intermediary device manages static charges without requiring voltage application to the pressure roller, thereby preventing contamination of the pressure roller surface.
3Object-affected harmful factors
If the fusing belt or pressure roller surface is made conductive and connected to ground, then static electricity is controlled, but the design complexity increases
Solution Approach 1:
The invention extracts static electricity from the print medium using a simple discharging member with a conductive brush, avoiding the need to modify the fusing belt or pressure roller with conductive materials. This extraction approach reduces design complexity by maintaining the original non-conductive properties of the fusing components while still controlling static electricity.
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 prevents image loss and contamination by stabilizing the electrostatic charges, ensuring consistent toner adherence and reducing defects like white or black bands, while maintaining a simpler design by eliminating the need for a voltage-applying discharging plate.
Implementation Method 1
a discharging brush efficiently discharges static from the print medium
Implementation Method 2
a conductive pressure roller with controlled surface resistance, which manages static electricity
Implementation Method 3
a heating member and a pressure roller, heating and pressing the non-fusing toner image transferred to the print image to thereby fuse the toner image on the print medium
Data Source
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AI summary
A fusing unit and an image forming apparatus, the fusing unit includes: a fusing frame which is grounded to the image forming apparatus when mounted in the image forming apparatus; a heating member which includes a release layer contacting the print medium and a heat transfer layer provided within the release layer, grounded to the fusing frame, and transfers heat from a heat source provided therein to a print medium passing a predetermined fusing nip; a supporting member which rotatably supports the heating member; a pressure roller, forms the fusing nip between the pressure roller and the heating member, presses the print medium passing the fusing nip and includes a conductive material; and a discharging member includes an end part which contacts the print medium passing the fusing nip, and discharges static electricity from the print medium.