Fixing Device Shielding Unit Asymmetric Cooling
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Solution Overview
Problem
Existing image forming apparatuses face challenges in suppressing non-sheet-passing portion temperature rise and maintaining fixing quality when the recording material is deviated from its ideal position, leading to reduced productivity.
Innovation Solution
The apparatus incorporates a shielding unit with adjustable cooling ports, controlled by a detection system that adjusts the opening widths of exhaust ports based on the recording material's width and shift amount, ensuring optimal cooling of non-sheet-passing regions and maintaining uniform temperature across the fixing nip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is blown to both end portions of the fixing device, then non-sheet-passing portion temperature rise is suppressed, but fixing property deteriorates at portions where cooling air is blown to regions through which recording material passes
Solution Approach 1:
The patent applies local quality by differentiating cooling treatment between the two end portions based on recording material position. When the recording material center is deviated, cooling is selectively applied only to the end portion where the material does not pass, while the other end portion receives no cooling. This localized approach prevents temperature rise in non-passing regions while avoiding harmful cooling effects in material-passing regions.
2Productivity
If the opening width of cooling ports is adjusted for different recording material sizes, then cooling efficiency is improved, but device complexity increases due to additional shutter mechanisms
Solution Approach 1:
The patent implements dynamics by making the cooling port opening widths adjustable rather than fixed. Shutters are provided at both end portions to dynamically control the opening widths according to the width of the recording material being processed. This allows the system to adapt to various material sizes while maintaining effective cooling, though it does increase device complexity through the addition of shutter mechanisms.
3Temperature
If cooling is applied to compensate for recording material shift, then temperature uniformity is improved, but productivity decreases due to reduced gap between recording materials
Solution Approach 1:
The patent resolves this contradiction by applying local quality through asymmetric cooling. When recording material shift is detected, cooling is applied only to the specific end portion where the material does not pass, rather than uniformly cooling both ends. This localized cooling compensates for temperature non-uniformity caused by material shift while avoiding the need to reduce the gap between materials, thereby maintaining productivity.
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 prevents non-sheet-passing portion temperature rise and maintains fixing quality even when the recording material is deviated, thereby ensuring consistent productivity and preventing a deterioration in fixing properties.
Implementation Method 1
a fixing device in which an air blowing port (opening) through which cooling air from a cooling fan blows out is provided at each of non-sheet-passing portions
Implementation Method 2
a heating unit (21) for heating the recording material (P)
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
An image forming apparatus includes a fixing unit including a heater, an air blowing portion, a first opening, a first shielding member changing an opening width of the first opening with respect to a longitudinal direction, a second opening, a second shielding member changing an opening width of the second opening with respect to the longitudinal direction, a detecting portion detecting a deviation amount of the recording material with respect to a widthwise direction, and a controller controlling, on the basis of an output of the detecting portion and size information of the recording material, the opening widths of the first and second openings so as to be different from each other by moving the first and second shielding members, respectively.