Fixing Device Pressing Mechanism for Envelope Mode
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses lack an operational mode that adjusts the pressing force for envelopes, which requires a lower pressing force compared to traditional paper sheets, and existing solutions fail to efficiently manage this force variation without compromising the direction of the pressing force.
Innovation Solution
A fixing device with a pressing mechanism that includes a movable pressing member, urging members, and a guide member, allowing for selective adjustment of pressing force between normal and envelope modes by switching between different spring configurations, ensuring consistent directionality of the pressing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed pressing force is applied to the recording medium, then the image fixing is reliable for normal paper sheets, but the pressing force is too strong for envelopes causing damage or poor fixing quality
Solution Approach 1:
The pressing member is designed to be movable between a first position (contacting the first contact body) and a second position (separated from the first contact body). By dynamically changing the position of the pressing member, the pressing force can be adjusted between a first pressing force (for normal paper sheets) and a second pressing force (for envelopes), allowing adaptation to different recording media without increasing overall mechanism complexity
Solution Approach 2:
The pressing force parameter is changed by selectively positioning the pressing member in different states. When the pressing member contacts the first contact body, a first pressing force is applied; when separated, a second pressing force is applied. This parameter change enables the fixing device to handle both normal paper sheets and envelopes with appropriate pressing forces
2Adaptability or versatility
If the pressing member is made movable to adjust pressing force, then adaptability to different media is improved, but the mechanism size increases
Solution Approach 1:
The guide member combines multiple functions: it guides the movement of the pressing member, provides a positioning surface for the pressing member to contact, and works with the urging member to control the pressing force. By merging these functions into a single integrated component, the overall size of the fixing unit is reduced while still enabling mode switching capability
Solution Approach 2:
The urging member acts as an intermediary between the pressing member and the guide member, providing the necessary force to move the pressing member between positions. This intermediary mechanism allows for compact design by using spring force rather than requiring large actuators or motors, thus reducing the volume of the fixing unit
3Force
If the pressing member is separated from the first contact body, then the pressing force is reduced for envelopes, but the direction of the pressing force may become unstable
Solution Approach 1:
The second urging member is extracted as a separate component interposed between the pressing member and the guide member. This second urging member specifically provides the force to maintain the pressing member in the separated position while ensuring stable directional control through the guide member's groove structure, thus maintaining force direction stability even when the pressing force magnitude is reduced
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
Enables adjustable pressing force between normal and envelope modes without altering the force direction, ensuring high transportability of the recording medium and reducing the size of the fixing unit, while allowing for easy mode switching.
Implementation Method 1
a first urging member that urges the pressing member to apply a force to the first contact body through the pressing member; a second urging member that is interposed between the pressing member and the guide member and that urges the guide member to apply a force to the first contact body through the guide member
Data Source
AI summary
A fixing device includes first and second contact bodies that apply a pressure to a recording medium to fix an unfixed image on the recording medium; a pressing member that is movable between a first position at which the pressing member is in contact with the first contact body and a second position at which the pressing member is separated from the first contact body; a first urging member that urges the pressing member to apply a force to the first contact body; a guide member that controls a direction in which the first contact body moves; a second urging member that is interposed between the pressing member and the guide member and that urges the guide member to apply a force to the first contact body; and a changer that selectively changes a position of the pressing member between the first and second positions.