Fixing Device Stay Design for Belt Rigidity
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Solution Overview
Problem
In image forming apparatuses, small-sized fixing belts with reduced thermal capacity lead to poor fixing quality due to bending or torsion of the nip formation member during start-up, affecting the pressure pattern and nip width, especially at high speeds.
Innovation Solution
A fixing device with a stay having a base portion and inclined rise portions that support the nip formation member, increasing mechanical strength and preventing bending or torsion, while direct heating of the fixing belt reduces thermal capacity and enhances energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a small-sized fixing belt is used to reduce thermal capacity, then energy consumption is reduced and warm-up time is shortened, but the nip formation member bends or torsions during start-up, degrading fixing quality
Solution Approach 1:
The stay is designed with an inclined rise portion that extends in the circumferential direction of the fixing belt, adding a dimensional component along the belt's rotation path. This inclined structure effectively increases the stay's length and rigidity in the circumferential direction without increasing the fixing belt's diameter, thereby preventing nip formation member deformation during start-up while maintaining the small size and low thermal capacity of the fixing belt
Solution Approach 2:
The stay is divided into distinct functional portions: a base portion that supports the nip formation member, and an inclined rise portion that provides additional circumferential support. This segmentation allows each portion to be optimized for its specific function - the base portion for radial support and the inclined rise portion for circumferential stiffness, resolving the contradiction between small size and sufficient rigidity
2Loss of energy
If the fixing belt diameter is reduced to approximately 30 mm, then thermal efficiency is increased, but the support member rigidity is reduced, making it difficult to prevent bending or torsion
Solution Approach 1:
By extending the stay in the circumferential direction through the inclined rise portion, the design compensates for the reduced rigidity caused by the small fixing belt diameter. This dimensional extension provides the necessary structural strength without increasing the belt size, thereby maintaining both thermal efficiency and support member rigidity
Solution Approach 2:
The stay's geometry is changed by introducing an inclined rise portion with a specific inclination angle (α) relative to the radial direction. This parameter change optimizes the distribution of mechanical stresses during start-up, providing sufficient rigidity to prevent nip formation member deformation while maintaining the compact 30 mm fixing belt diameter for high thermal efficiency
3Reliability
If a stay with sufficient rigidity is designed, then bending or torsion of the nip formation member is prevented, but the stay becomes large-sized, increasing device complexity
Solution Approach 1:
Rather than increasing the stay's radial height or thickness, the design extends the stay in the circumferential direction through the inclined rise portion. This approach provides the necessary rigidity to prevent nip formation member deformation while maintaining a compact overall structure, avoiding unnecessary complexity in the stay design
Solution Approach 2:
The inclined rise portion of the stay serves multiple functions: it provides circumferential support to prevent deformation, guides the nip formation member during start-up, and maintains structural compactness. This multi-functionality reduces the need for additional components, thereby simplifying the overall device structure while ensuring reliable prevention of bending or torsion
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 prevents bending or torsion of the nip formation member, maintains good fixing properties even at high speeds, and reduces energy consumption by direct heating, ensuring consistent image quality and shortened warm-up and first print times.
Implementation Method 1
a heat source 123 which is a heating unit to heat the fixing belt 121 in a region fully covering a width of a sheet by radiant heat
Data Source
Figure 1
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AI summary
A fixing device (20) includes a support member (25) disposed to support a nip formation member on an inner peripheral surface of a fixing belt (21). The support member includes a parallel portion (25a) that supports the nip formation member (24) and extends parallel to a sheet transport direction in a nip portion, and a rise portion (25b) that extends from the parallel portion in a direction drawn apart from the nip portion. The rise portion is inclined to the parallel portion such that an inclination direction of the rise portion is substantially parallel to a virtual straight line (L) connecting a center of rotation (X) of the fixing belt and an inlet point (Y) of the nip portion or falls within a range of rotational angles of ± 15° by which the virtual straight line is rotated around the center of rotation of the fixing belt.