Fixing Device Outlet Guide Member for Recording Sheet Curl Control
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Solution Overview
Problem
In image forming apparatuses using electrophotography, the recording sheet often curls sharply due to temperature differences during the fixing process, leading to potential paper jams in the sheet feeding and ejection paths.
Innovation Solution
The implementation of an auxiliary driven roller and an outlet guide member downstream of the fixing nip, which forms an auxiliary nip portion to further process the recording sheet and guide it with a concave bent surface, reducing curl and preventing jams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heating roller and pressure belt are used to fix toner images, then toner fixation is achieved, but the recording sheet curls sharply due to temperature difference
Solution Approach 1:
A cooling roller is introduced as an intermediary component between the heating roller and the recording sheet. The cooling roller applies localized cooling to the heated portion of the recording sheet, acting as a mediator that counteracts the thermal effects causing curl while preserving the necessary heating for toner fixation.
Solution Approach 2:
The cooling roller applies cooling only to the specific region of the recording sheet that has been heated by the heating roller, rather than cooling the entire sheet. This localized treatment addresses the temperature difference-induced curl at its source while maintaining the overall fixation quality.
2Reliability
If the recording sheet is heated at the nip portion, then toner image is fused and fixed, but paper jam occurs in sheet feeding path or ejection outlet
Solution Approach 1:
The cooling roller serves as a mediator that immediately follows the heating process, transitioning the recording sheet from a heated state to a cooled state. This intermediate cooling step prevents the sheet from maintaining a curled configuration that would cause jamming in downstream paths.
Solution Approach 2:
The temperature difference that initially causes harmful curling is converted into a beneficial effect by intentionally applying localized cooling. The same thermal gradient that causes problems is harnessed and controlled to achieve the desired flattening effect, preventing paper jams while maintaining effective toner fixation.
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 curl of the recording sheet and prevents paper jams by guiding the sheet with a concave bent surface, ensuring smooth feeding and ejection.
Implementation Method 1
a heater to heat the fixing belt to fuse and fix toner onto a recording sheet in the nip portion
Implementation Method 2
an outlet guide member, disposed downstream of the auxiliary nip portion in the recording sheet feeding direction, to guide the recording sheet after toner fixation conveyed from the auxiliary nip portion, with the recording sheet bent such that a surface of the recording sheet on which toner fixation has occurred is bent in a concave shape
Data Source
AI summary
A fixing device includes an endless fixing belt; a pressure roller to contact the fixing belt; a nip forming member to press the pressure roller from the fixing belt; a nip portion formed between the fixing belt and the pressure roller; a heater to heat the fixing belt to fuse and fix toner onto a recording sheet in the nip portion; an auxiliary driven roller; an auxiliary drive roller to drive the driven roller; an auxiliary nip portion, formed between an outer circumferential surface of the auxiliary driven roller and an outer circumferential surface of the auxiliary drive roller, to nip the recording sheet after toner fixation conveyed from the nip portion; and an outlet guide member, disposed downstream of the auxiliary nip portion, to guide the recording sheet after toner fixation conveyed from the auxiliary nip portion, with the toner-fixed recording sheet surface bent in a concave shape.