Fixing Device Holder With Non-Uniform Thickness For Uniform Nipping Pressure
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Solution Overview
Problem
In fixing devices with pressure rollers having an inverted crown shape, the nipping width at each axial end becomes greater, leading to uneven nipping pressure and potential wrinkles on sheets.
Innovation Solution
The fixing device incorporates a pressure roller with an inverted crown shape and a holder with contacting surfaces arranged such that the distance between the heater supporting surface and the contacting surface is greater at the center than at the ends, maintaining consistent nipping pressure across the axial direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the pressure roller has an inverted crown shape, then the sheet can be conveyed while stretching from the center toward the axial ends restraining wrinkles, but the nipping width at each axial end becomes greater
Solution Approach 1:
The holder is designed with non-uniform thickness in the axial direction, where the thickness at the center is smaller than at the axial ends. This creates local variation in the holder's mechanical properties, allowing the center portion to be more compliant and compensate for the increased nipping width at the ends caused by the inverted crown shape of the pressure roller.
Solution Approach 2:
The invention changes the geometric parameter of the holder (thickness distribution along axial direction) to alter the nipping pressure distribution. By making the holder thinner at the center and thicker at the ends, the effective nipping width is regulated to maintain uniformity across the axial direction, counteracting the effect of the pressure roller's inverted crown shape.
2Object-affected harmful factors
If the pressure roller has an inverted crown shape, then the sheet stretching force is applied from center toward ends, but the nipping pressure becomes uneven across the axial direction
Solution Approach 1:
The holder's thickness varies locally along the axial direction, with the center being thinner and the ends being thicker. This local quality variation compensates for the non-uniform pressure distribution caused by the inverted crown shape, ensuring more uniform nipping pressure across the entire axial length.
Solution Approach 2:
The holder is designed with asymmetric thickness distribution relative to the pressure roller's inverted crown shape. This asymmetric design creates a compensating effect where the thinner center portion and thicker end portions balance out the pressure variations, achieving uniform nipping pressure despite the asymmetric pressure roller geometry.
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 effectively suppresses the increase in nipping width at each end of the pressure roller, ensuring uniform nipping pressure and preventing wrinkles on sheets, even with the inverted crown shape of the pressure roller.
Implementation Method 1
The heater includes: a base plate; and a resistance heating element provided on the base plate
Data Source
AI summary
A fixing device includes: an endless belt; a heater; a stay; a holder having a heater supporting surface and a contacting surface in contact with the stay; and a pressure roller having a diameter that becomes smaller from each end of the pressure roller in an axial direction toward a center of the pressure roller in the axial direction. In a state prior to assembling the holder with both the stay and the heater, a distance in an orthogonal direction between the heater supporting surface and the contacting surface at a center of the holder in the axial direction is longer than a distance in the orthogonal direction between the heater supporting surface and the contacting surface at each end of the holder in the axial direction. The orthogonal direction is orthogonal to the axial direction.