Fixing Device Cam Surface Pressure Angle Optimization
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Solution Overview
Problem
Existing fixing devices with adjustable nip pressure mechanisms experience undesirable cam surface advance due to excessive spring biasing, leading to uncomfortable noise, particularly when the biasing force on the second cam surface is greater than on the first, causing uneven pressure distribution and noise.
Innovation Solution
A fixing device with a pressure control mechanism that includes a cam with a first and second cam surface, where the second cam surface has a greater angle of action and a smaller maximum pressure angle than the first, to restrain undesirable cam surface advance by the spring biasing force, ensuring smooth operation and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the biasing force of the spring on the second cam surface is greater than on the first cam surface, then the nip pressure control range is improved, but undesirable cam surface advance occurs causing noise
Solution Approach 1:
The patent applies parameter changes by carefully designing the pressure angles of the cam surfaces. Specifically, the maximum pressure angle of the second cam surface is made smaller than that of the first cam surface, while maintaining greater biasing force on the second cam surface. This parameter optimization allows the system to achieve extended nip pressure control range without generating harmful noise from cam surface advance.
2Adaptability or versatility
If the angle of action of the second cam surface is greater than the first, then the pressure adjustment range is improved, but the risk of cam surface advance increases
Solution Approach 1:
The patent resolves this contradiction through parameter changes in cam surface geometry. By making the maximum pressure angle of the second cam surface smaller than that of the first cam surface, the design achieves greater angle of action for the second cam surface while preventing cam surface advance, thus maintaining reliability during extended pressure adjustment.
3Reliability
If the maximum pressure angle at the second cam surface is smaller than at the first cam surface, then cam surface advance is restrained, but the cam surface design complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the cam surface into distinct first and second cam surfaces with different pressure angle characteristics. This segmentation allows each cam surface to be optimized independently - the first cam surface has a larger maximum pressure angle for initial pressure adjustment, while the second cam surface has a smaller maximum pressure angle for stable fine-tuning, thereby reducing overall design complexity.
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 undesirable advance of the cam surface, reducing noise and maintaining consistent pressure distribution across varying nip pressures, enhancing the operational stability and quietness of the fixing device.
Implementation Method 1
The first spring is arranged to bias the arm with a first biasing force
Implementation Method 2
The cam is rotatably arranged to cause the arm to move against the first biasing force
Data Source
AI summary
In a fixing device, a first fixing member and a second fixing member are configured to form a nip in combination, and an arm biased by a first spring with a first biasing force provides a nip pressure. A cam rotatably arranged to cause the arm to move against the first biasing force has a first cam surface used to change the nip pressure from a first pressure to a second pressure smaller than the first pressure, and a second cam surface of which an angle of action is greater than that of the first cam surface to change the nip pressure from the second pressure to a third pressure smaller than the second pressure. A maximum pressure angle at the second cam surface is smaller than a maximum pressure angle at the first cam surface.