Fixing Device Asymmetric Leverage Ratio Independent Nip Force Control
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Solution Overview
Problem
Existing fixing devices face challenges in varying the pressing forces of the heating nip and pressure nip independently, often requiring additional springs which increase the number of parts and complexity.
Innovation Solution
A fixing device with a first and second pressure structure, a fixing member, and pivotable arms with different leverage ratios, connected by an elastic member, allowing for adjustable pressing forces without the need for additional springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one spring is used to bias both the heater arm and the pressure roller arm, then the number of parts is reduced, but the pressing forces of the heating nip and pressure nip cannot be varied independently
Solution Approach 1:
The patent changes the mechanical parameter (leverage ratio) of the arms to achieve different pressing forces. By designing the first arm with a first leverage ratio and the second arm with a second leverage ratio that is greater than the first, the system can independently control the pressing forces at the heating nip and pressure nip while using only one spring, thus resolving the contradiction between part reduction and force adjustment capability
2Adaptability or versatility
If two springs of different pressing forces are used to bias the heater arm and pressure roller arm respectively, then independent pressing force control is achieved, but the number of parts increases
Solution Approach 1:
Instead of using two springs with different forces, the patent changes the leverage ratio parameter of the arms. The second arm is designed with a greater leverage ratio than the first arm, which amplifies the spring force differently at each nip point. This allows independent pressing force control with a single spring, reducing part count while maintaining the desired adaptability
3Device complexity
If the heater arm and pressure roller arm have the same leverage, then the structure is simplified, but the heating nip and pressure nip have the same pressing forces which may not be desirable
Solution Approach 1:
The patent introduces asymmetry in the leverage ratios of the two arms. The second arm has a greater leverage ratio than the first arm, creating an asymmetric force distribution. This asymmetric design allows the pressing forces at the heating nip and pressure nip to be different, meeting the requirement for force differentiation while maintaining relatively simple arm structures
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 configuration enables independent adjustment of pressing forces at the nips, enhancing heat fixing reliability and reducing the number of parts required, while maintaining efficient temperature rise and minimizing mechanical stress.
Implementation Method 1
The elastic member is connected to the first connection portion and the second connection portion and configured to bias the first pressing portion and the second pressing portion toward each other
Implementation Method 2
a heater configured to heat the fixing member
Data Source
AI summary
A fixing device includes a first pressure structure, a second pressure structure, a fixing member, a first arm, a second arm, and an elastic member. The fixing member is disposed between the first and second pressure structures. The first arm is pivotable about a first shaft and includes a first pressing portion and a first connection portion. The second arm is pivotable about a second shaft and includes a second pressing portion and a second connection portion. The elastic member biases the first and second pressing portions toward each other. A first leverage ratio of a distance between the first shaft and the first connection portion to a distance between the first shaft and the first pressing portion is different from a second leverage ratio of a distance between the second shaft and the second connection portion to a distance between the second shaft and the second pressing portion.