Sheet Separating Board and Discharging Rollers for Curl Correction
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in correcting sheet curl caused by the fixing unit, requiring adjustments in rolling angle and pressure, which can compromise image quality and increase costs, especially when using a discharging roller with subsidiary rollers.
Innovation Solution
An image forming apparatus that corrects sheet curl by using a sheet separating board to alter the discharging direction and a pair of sheet discharging rollers, with the sheet separating board angled between 75 degrees to 95 degrees and the nip depth of the discharging rollers ranging from 0 mm to 3 mm, to effectively manage curl correction without degrading image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rolling angle of the discharging roller is increased to correct curl, then the curl correction effect is improved, but the image quality of the imprinted sheet is degraded
Solution Approach 1:
A subsidiary roller is introduced as an intermediary component between the discharging roller and the sheet. The subsidiary roller contacts the sheet and applies reverse curl force, while the discharging roller maintains its primary discharging function without needing to increase its rolling angle, thus preventing image quality degradation
Solution Approach 2:
The curl correction function is segmented from the discharging roller function. Instead of relying solely on the discharging roller to perform both discharging and curl correction, the system divides these functions: the discharging roller handles sheet discharge, while the subsidiary roller handles curl correction through reverse curling action
2Manufacturing precision
If the pressure of the subsidiary rollers against the discharging roller is increased to correct curl, then the curl correction effect is improved, but the image quality of the imprinted sheet is decreased
Solution Approach 1:
The subsidiary roller is positioned to contact the sheet at a specific location (downstream of the fixing roller) where curl correction is most effective. By localizing the reverse curl action at this specific position rather than applying pressure across the entire discharging roller surface, the system achieves effective curl correction without degrading image quality
3Manufacturing precision
If two subsidiary rollers are added to correct curl, then the curl correction capability is improved, but the cost of the fixing unit increases
Solution Approach 1:
The subsidiary roller is designed to perform multiple functions: it corrects sheet curl through reverse curling action, and can also serve as a support element in the fixing unit structure. This multi-functionality reduces the need for additional separate components, thereby controlling the overall cost increase
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 solution effectively corrects sheet curl across various paper types, ensuring proper sheet transportation and stacking while maintaining image quality and reducing the need for costly adjustments and components.
Implementation Method 1
a sheet separating board, disposed downstream of the fixing device, positioned in a paper path of the imaging forming apparatus and to alter discharging direction of a sheet discharged from the fixing device by contact with the sheet
Implementation Method 2
a pair of sheet discharging rollers is disposed downstream of the fixing device and the sheet separating board and is arranged to correct curl of the sheet discharged from the fixing device
Implementation Method 3
a pair of sheet discharging rollers is disposed downstream of the fixing device and the sheet separating board and is arranged to correct curl of the sheet discharged from the fixing device
Implementation Method 4
The fixing unit uses heat and pressure to fix a toner image on a sheet passing through nip portion formed between the fixing device and a pressing device
Implementation Method 5
The fixing unit uses heat and pressure to fix a toner image on a sheet passing through nip portion formed between the fixing device and a pressing device
Data Source
AI summary
An image forming apparatus which uses toner to form an image on a sheet may cause the sheet to experience curl after passing through a fixing device which uses heat and pressure to fix the toner image on the sheet. A pair of discharge rollers and/or a sheet separating board may be utilized to correct the curl on the sheet, for both thin and heavy paper weights. The angle of the sheet separating board relative to a line which is perpendicular to a sheet discharging direction is preferably set from 75° to 95°, and a nip depth of a pair of sheet discharging rollers is preferably set from 0 mm to 3 mm.