Fixing Device Nip Width Adjustment for Belt Heat Management
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Solution Overview
Problem
Conventional fixing devices with high heat capacity pressure rollers cause heat loss, leading to delayed temperature reaching during warm-up and potential overheating of the endless belt, which accelerates its deterioration.
Innovation Solution
A fixing device with an adjustment mechanism that controls the nip width between the heating member and pressure roller, ensuring A>B≥N, where A is the nip width during fixing, B is the nip width during temperature raising, and N is the heat generating element length, to optimize heat transfer and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the pressure roller is separated from the endless belt during warm-up, then the temperature reaching speed is improved, but the contact region of the endless belt with the heat generating member may be excessively heated
Solution Approach 1:
The nip width between the heating member and pressure roller is made dynamically adjustable rather than fixed. During warm-up, the nip width is reduced to minimize heat loss to the pressure roller while preventing excessive heating of the endless belt. During fixing operations, the nip width is increased to ensure proper contact and fixing quality. This dynamic adjustment resolves the contradiction by adapting the system to different operational states.
Solution Approach 2:
The patent changes the physical parameter of nip width based on operational requirements. By controlling the nip width to satisfy A>B≥N (where A is nip width during fixing, B is nip width during temperature raising, and N is heat generating element length), the system optimizes heat transfer characteristics for different phases of operation, preventing both heat loss during warm-up and excessive heating during fixing.
2Reliability
If the pressure roller has high heat capacity, then the pressure and heating function is improved, but the heat for heating the endless belt is taken away causing delay in reaching specified temperature
Solution Approach 1:
The system dynamically adjusts the nip width based on operational state. During warm-up, the reduced nip width (B) minimizes thermal contact between the high heat capacity pressure roller and the heating member, reducing heat loss and accelerating warm-up. During fixing operations, the full nip width (A) ensures proper pressure and heat transfer for reliable fixing.
Solution Approach 2:
The system performs preliminary warm-up with a reduced nip width configuration before transitioning to the full fixing operation. This preliminary action allows the heating member to reach the required temperature quickly by minimizing heat loss to the pressure roller, ensuring the fixing function is ready when needed without unnecessary delay.
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 allows for faster temperature reaching of the heating member while preventing excessive heat transfer to the pressure roller, thereby reducing the risk of endless belt deterioration and improving the fixing device's performance.
Implementation Method 1
the heating member is in contact with the inner surface of the endless belt and heats the endless belt
Implementation Method 2
the pressure roller and the second surface of the sheet are in contact with each other, allowing the plate-shaped heat generating member and the pressure roller to produce pressure
Data Source
AI summary
A fixing device according to an embodiment includes an endless belt, a pressure element, a heating member, an adjustment mechanism, and a controller. The pressure element conveys and presses a sheet to the endless belt. The heating member is on the inner side of the belt and has a heat generating element for heating the belt. The adjustment mechanism moves the heating member or the pressure element to adjust the nip width between the heating member and the pressure element. The controller controls the adjustment mechanism so that A>B≥N is satisfied, where A is the nip width during a fixing process in which a colored material is fixed to the sheet, B is the nip width during a heating process conducted before the fixing process, and N is the length of the heat generating element in the sheet conveyance direction.