Fixing Device Nip Width Control Mechanism
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Solution Overview
Problem
Existing fixing devices face issues with maintaining proper nip width during thermal fixing due to changes in pressure roller hardness, leading to suboptimal fixing performance when the nip width exceeds the allowable range.
Innovation Solution
A fixing device with a change member that adjusts the nip width between a first and second nip width, featuring a restriction portion to limit the movement of the first fixing member and maintain the maximum first nip width, and a flexible cylindrical member to form the nip portion, ensuring consistent fixing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure roller receives the entire urging force when the nip width is the first nip width, then the thermal fixing can be performed, but the pressure roller hardness changes with use and the nip width becomes larger than the maximum allowable range
Solution Approach 1:
The cam acts as an intermediary element between the urging mechanism and the heat member. When the cam engages with the arm member, it mediates the urging force to maintain a controlled nip width. This intermediary mechanism prevents the heat member from moving too closely to the pressure roller, thereby preventing the nip width from exceeding the maximum allowable range while still enabling proper thermal fixing.
Solution Approach 2:
The system dynamically adjusts the nip width by engaging and disengaging the cam with the arm member. When the cam engages, it restricts the arm member's movement to maintain a smaller nip width for jamming processing. When disengaged, the full urging force is applied to achieve the first nip width for thermal fixing. This dynamic engagement ensures the nip width remains within acceptable ranges under different operating conditions.
2Adaptability or versatility
If the cam presses the arm member against the urging force, then the nip width becomes the second nip width for jamming processing, but the structure becomes more complex
Solution Approach 1:
The cam mechanism serves multiple functions: it acts as a pressure application element for jamming processing, a width control element for nip width adjustment, and a force transmission element between the urging mechanism and the heat member. By making this single component multi-functional, the patent achieves nip width adjustment capability without proportionally increasing the overall structural complexity.
Solution Approach 2:
The cam combines the functions of force transmission and width control into a single integrated element. Rather than using separate mechanisms for these functions, the cam geometry is designed to simultaneously transmit urging force and control the relative position of the heat member, thereby merging multiple functions into one component.
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 effectively restricts the nip width to prevent excessive expansion, ensuring proper thermal fixing performance even when the pressure roller softens, thereby maintaining consistent and reliable fixing results.
Implementation Method 1
a heat member that applies heat to a recording sheet
Implementation Method 2
a pressure roller that forms a nip portion between the pressure roller and the heat member
Data Source
AI summary
A fixing device may include first and second fixing members arranged to form a nip portion, an urging member that provides an urging force to urge the first fixing member toward the second fixing member, a change member configured to change a width of the nip portion from a first nip width to a second nip width by applying a pressing force to the first fixing member against the urging force of the urging member and change the width of the nip portion from the second nip width to the first nip width by releasing the pressing force, and a restriction portion configured to restrict movement of the first fixing member and restrict a maximum value of the first nip width of the nip portion while the pressing force against the urging force is released.