Fixing Device Ducted Air Exhaust for Uniform Sheet Cooling
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Solution Overview
Problem
Image forming apparatuses face issues with condensation causing jams and uneven image gloss due to water vapor release during the fixing process, as existing solutions with two nip portions in the sheet widthwise direction lead to uneven heating and cooling of the sheet.
Innovation Solution
A fixing device with a blowing portion and ducts to ventilate the space between the fixing and feeding roller pairs, ensuring uniform air flow and contact over the sheet's width, which reduces condensation and uneven cooling by exhausting air through strategically placed ducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a first feeding roller pair with two nip portions is used to exhaust water vapor, then condensation and image defects are reduced, but uneven gloss occurs due to uneven cooling of the sheet
Solution Approach 1:
The feeding roller pair is divided into two separate roller pairs (first and second feeding roller pairs) positioned at different locations downstream of the fixing device. Each roller pair independently contacts the sheet at different positions, allowing distributed cooling that prevents localized overheating while maintaining uniform gloss across the image surface.
Solution Approach 2:
The solution transitions from a single roller pair with two nip portions (one dimension of contact) to two separate roller pairs positioned at different downstream locations (adding a longitudinal dimension). This spatial distribution allows water vapor exhaust while providing uniform cooling across the sheet width without concentrated quenching points.
2Object-generated harmful factors
If the sheet is quenched by contact with the first feeding roller pair, then water vapor is exhausted, but uneven gloss is caused due to uneven cooling
Solution Approach 1:
The cooling function is segmented across two separate feeding roller pairs positioned at different downstream locations. The first feeding roller pair handles initial cooling and water vapor exhaust, while the second feeding roller pair provides additional cooling further downstream. This segmentation distributes the thermal load and prevents localized quenching that causes uneven gloss.
Solution Approach 2:
The cooling action is made continuous through the sequence of two feeding roller pairs arranged downstream. Instead of a single discrete cooling event that causes sudden temperature changes and uneven gloss, the cooling occurs progressively as the sheet passes through both roller pairs, maintaining more uniform temperature distribution and consistent gloss.
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 reduces condensation and image defects, providing high-quality results by stabilizing humidity and ensuring consistent sheet cooling, thus enhancing the image forming process.
Implementation Method 1
a blowing portion configured to blow air toward said feeding passage
Implementation Method 2
a first duct configured to guide the air from said blowing portion and communicate with said feeding passage at a first position... and a second duct configured to guide the air from said blowing portion and communicate with said feeding passage at a second position
Implementation Method 3
a fixing portion configured to heat a toner image formed on a first side of a sheet and to fix the toner image on the sheet
Implementation Method 4
the sheet before it is fixed contains some moisture, and when it is heated during the fixing of the toner image, water vapor is released from the sheet
Implementation Method 5
a first rotatable member pair provided on a downstream side of said fixing device with respect to a sheet feeding direction and configured to feed the sheet
Data Source
AI summary
A fixing device includes a first feeder provided downstream of a fixing portion heating a toner image formed on a first side of a sheet in a feeding direction, a second feeder provided adjacent downstream of the first feeder, and a guide contacting with a second side of the sheet fed by the first feeder and guiding toward the second feeder, a blower, a first duct guiding the air at a first position between the first and feeders, and a second duct at a second position between the first position and the first feeder. The first and second feeders are contactable to the sheet over an entire width. The air from the blower passes through the first duct, is sent to a feeding passage formed between the first and second feeders from the first position, and sent to the second side, then, the air passes through the second duct from the feeding passage via the second position and is exhausted.