Fixing Device Pressing Unit for Crease Prevention and Media Conveyance
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Solution Overview
Problem
The fixing device in image forming apparatuses sometimes weakens the pressing force to prevent creases in recording media, leading to insufficient pressing of the heating roller by the pressurizing belt, which hinders the conveyance of recording media, especially when handling stacked recording media.
Innovation Solution
A fixing device with a pressing unit that can switch between pressing and release positions, using a pushing member and an urging member to maintain a consistent pressing force, ensuring the pressurizing belt follows the heating roller without significant force reduction, even in the release position, thus preventing creases and ensuring smooth conveyance of stacked media.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pressing force is weakened to prevent creases in recording medium, then crease prevention is improved, but the pressurizing belt cannot follow the heating roller properly and recording medium conveyance is hindered
Solution Approach 1:
The pressing unit applies different pressing forces at different locations and times: strong pressing force is applied at the entrance region to ensure the pressurizing belt follows the heating roller and enable smooth conveyance, while reduced pressing force is applied at the exit region to prevent creases in the fixed recording medium
Solution Approach 2:
The pressing force is made dynamically adjustable through the pressing unit that can switch between pressing and release positions. The pressing force is continuously varied along the conveying direction, being stronger at the entrance and weaker at the exit, allowing optimal conveyance and crease prevention at different stages
2Object-affected harmful factors
If the pressing force is weakened to prevent creases in recording medium, then crease prevention is improved, but pressing of the heating roller by the pressurizing belt becomes insufficient
Solution Approach 1:
The pressing unit provides locally differentiated pressing force: strong pressing at the entrance region ensures adequate contact between pressurizing belt and heating roller for proper belt following, while reduced pressing at the exit region prevents creases in the already-fixed recording medium
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 solution maintains a consistent pressing force, preventing creases in stacked media while ensuring the pressurizing belt continues to rotate with the heating roller, thereby facilitating the conveyance of recording media without hindrance and ensuring effective toner fixation.
Implementation Method 1
a first rotating body which is turned by a heat source
Implementation Method 2
an urging member which urges the pressing unit in a first direction in which the second rotating body approaches the first rotating body
Implementation Method 3
The pressing unit presses a recording medium such as a sheet against the heating roller to thereby thermally fix toner to the recording medium
Data Source
AI summary
A fixing device according to an embodiment includes a first rotating body, a pressing unit, and an urging member. The pressing unit includes a belt, a second rotating body, a belt supporting member, and a pushing member. The pushing member includes a pressing region for pressing the belt toward the first rotating body. The pushing member is disposed between the second rotating body and the belt supporting member. The pressing unit is capable of switching a pressing position and a release position. When viewed from the axial direction of the first rotating body, a line connecting the center of the first rotating body and the center of the turning fulcrum passes the pressing region of the pushing member in both of the pressing position and the release position.