Fixing Portion Opening Position for Vapor Condensation Control
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Solution Overview
Problem
In image forming apparatuses using the electrophotographic method, water vapor from the recording medium condenses on the photosensitive member due to air blown by adjacent air blowing apparatuses, disrupting the surface potential and reducing image quality.
Innovation Solution
The image forming apparatus includes a fixing portion positioned higher than the photosensitive member, with rotatable members forming a fixing nip, covered by protective members featuring strategically placed openings for fluid communication, which reduces airflow and vapor condensation on the photosensitive member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the fixing portion is provided with openings for water vapor release, then water vapor condensation on the photosensitive member is prevented, but airflow from air blowing apparatuses can enter the fixing portion and carry water vapor toward the photosensitive member
Solution Approach 1:
The invention utilizes the air flow from air blowing apparatuses, which was previously harmful, to create a beneficial effect. By positioning the opening at the lower end of the fixing portion, the incoming air flow is directed to exit at the upper end, creating an upward flow that prevents water vapor from reaching the photosensitive member. The harmful air flow is thus converted into a protective flow pattern.
Solution Approach 2:
The opening in the fixing portion acts as an intermediary element that controls the interaction between the external air flow and the internal fixing environment. By strategically positioning this opening, the invention mediates the air flow to create a protective barrier that prevents water vapor condensation while allowing necessary ventilation.
2Object-affected harmful factors
If openings are provided in the fixing portion for fluid communication, then water vapor can be released, but the structural integrity and sealing of the fixing portion is compromised
Solution Approach 1:
The invention applies local quality by providing an opening at a specific location (lower end) of the fixing portion rather than uniformly throughout. This localized opening allows water vapor release while maintaining sealing integrity in other critical areas, particularly around the photosensitive member and upper fixing regions.
Solution Approach 2:
The invention addresses the sealing problem by transitioning from a two-dimensional sealing surface problem to a three-dimensional flow control solution. The opening's position and the resulting air flow pattern create a volumetric barrier that prevents water vapor migration, rather than relying solely on surface sealing.
3Object-affected harmful factors
If the fixing portion is positioned higher than the photosensitive member, then water vapor condensation is reduced, but the overall apparatus height increases
Solution Approach 1:
The invention introduces dynamics by utilizing the natural direction of air flow and water vapor movement. By positioning the opening at the lower end and relying on the upward flow pattern created by air blowing apparatuses, the system dynamically prevents water vapor condensation without requiring maximum vertical separation between components.
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 water vapor condensation on the photosensitive member, maintaining image quality by minimizing airflow and vapor exposure, even when the apparatus is near air blowing devices.
Implementation Method 1
as a sheet P of recording medium is heated by the heater 105, water vapor is generated from the sheet P
Implementation Method 2
at least one opening for fluid communication between an inside and an outside of the fixing portion
Data Source
AI summary
An image forming apparatus includes a photosensitive drum, an image forming portion for forming an image on the drum and for transferring the image to a sheet, and a fixing portion for fixing the image on the sheet, while heating the sheet in a fixing nip. The fixing portion is provided above the drum, and includes a first roller, a second roller cooperative with the first roller to form the fixing nip, first and second covers for protecting the first and second rollers, respectively, and at least one opening for fluid communication between an inside and an outside of the fixing portion, the opening being provided in the first cover at a position that is lower than a line connecting a rotation axis of the first roller and a rotation axis of the second roller, as seen along a rotational axis of the second roller.