Fixing Belt Shielding for Image Formers
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses face issues with excessive temperature rise in non-printing areas, leading to potential damage and degradation of the fixing belt, especially during continuous printing of regular-sized sheets.
Innovation Solution
Incorporating a shielding member between the fixing belt and the heat source, positioned outside the maximum sheet passing area, to prevent excessive heat from reaching non-printing regions, thereby maintaining the fixing belt within a safe temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the heat source directly heats the fixing belt at portions other than the nip to improve heating efficiency and reduce first print time, then the heating efficiency is improved and first print time is shortened, but the temperature of the fixing belt is excessively increased at non-sheet passing portions causing potential damage and degradation
Solution Approach 1:
The patent applies local quality by making the heat source structure asymmetric with different heat generation characteristics at different locations. The heat source includes a first heat generation portion for heating the sheet passing portion and a second heat generation portion for heating the non-sheet passing portion, with the second portion having smaller heat generation capacity. This local differentiation allows efficient heating where needed while preventing excessive temperature rise where sheets do not pass.
Solution Approach 2:
The patent changes the thermal parameters of the heat source by providing multiple heat generation portions with different heat generation capacities. The first heat generation portion has larger heat generation capacity than the second heat generation portion, creating a gradient in thermal energy distribution that matches the operational requirements of different belt regions.
2Stability of the object's composition
If the heat source heats the entire fixing belt including non-sheet passing portions to ensure uniform temperature distribution, then temperature uniformity is improved, but energy is wasted heating areas that do not require heating and the fixing belt may be damaged
Solution Approach 1:
The patent implements local quality by differentiating the heat generation capacity across different portions of the heat source. The first heat generation portion targets the sheet passing area with higher heat output, while the second heat generation portion targets the non-sheet passing area with reduced heat output, optimizing both energy efficiency and temperature control.
Solution Approach 2:
The patent converts the potential harm of excessive heating in non-sheet passing portions into a benefit by deliberately designing the second heat generation portion to provide controlled, lower-level heating. This prevents the harmful effects of overheating while maintaining sufficient temperature for belt stability, turning a potential problem into a solution.
3Object-affected harmful factors
If a shielding member is added to prevent excessive heating at non-sheet passing portions to protect the fixing belt, then protection against overheating is improved, but device complexity increases
Solution Approach 1:
The patent introduces a shielding member as an intermediary element positioned between the heat source and the fixing belt at the non-sheet passing portion. This shielding member selectively blocks excess heat radiation to the areas where sheets do not pass, preventing overheating while allowing the heating system to maintain its overall structure and function.
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
The shielding member effectively prevents excessive temperature rises in non-printing areas, ensuring the fixing belt operates within a safe temperature range, preventing damage and ensuring consistent print quality across various sheet sizes.
Implementation Method 1
the heat source 300 inside the metal conductive member 200 heats the endless belt 100 via the metal conductive member 200
Implementation Method 2
JP-2007-233011-A discloses an alternative method to heat the fixing belt directly, without the metal conductive member intermediary
Implementation Method 3
JP-2010-66583-A discloses an approach to solve the problem of excessive heating of the fixing belt, in which a shielding member is disposed between the heat source and the fixing belt
Data Source
AI summary
A fixing device includes a rotary endless fixing belt; a nip forming member disposed in an interior of the fixing belt; a rotary opposed member to contact the nip forming member via the fixing belt to form a nip together with the fixing belt; a heat source to directly heat the fixing belt at a portion other than the nip, including at lease one heat-generation part disposed outside lateral ends of a maximum area of the fixing belt where a recording medium passes through, wherein a recording medium carrying an unfixed image is conveyed to the nip and the fixing device fixes the unfixed image onto the recording medium; and a shielding member disposed between the fixing belt and the heat generation part of the heat source and configured to shield heat from the heat source at least at an area outside the maximum passing area of the recording medium.