Friction-Driven Pressure Belt for Stable Image Fixing
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Solution Overview
Problem
Existing image heating apparatuses in electrophotographic image forming devices suffer from unstable rotation of the pressure belt, leading to poor imaging quality due to varying conveying forces and friction coefficients, resulting in image displacements and poor gloss application.
Innovation Solution
An image heating apparatus with a rotatable heating member, an endless belt, and a driving roller, where the friction coefficient between the endless belt and the driving roller is set to be higher than between the heating member and the endless belt, ensuring stable peripheral speeds and reducing image displacements by maintaining consistent conveying forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the pressure belt is rotated by following movement of the fixing roller, then the structure is simple and can provide a long fixing nip portion, but the conveying force varies according to recording medium type, environmental conditions, and toner image type, resulting in unstable rotation of the pressure belt
Solution Approach 1:
The patent introduces a driving roller as an intermediary component between the power source and the pressure belt. This driving roller directly drives the pressure belt through frictional contact, serving as a mediator that decouples the pressure belt's rotation from the fixing roller's movement, thereby stabilizing the conveying force while maintaining structural simplicity
Solution Approach 2:
The patent replaces the mechanical following movement system (where the pressure belt passively follows the fixing roller) with a direct friction-driven system. The driving roller uses frictional contact to directly rotate the pressure belt, substituting the indirect mechanical coupling with a more controllable friction-based drive mechanism
2Reliability
If the pressure belt receives driving force only when the recording medium slips on the fixing roller, then the override mechanism can prevent lag, but it takes time to change from lower peripheral speed to receiving driving force, causing speed changes and image displacements
Solution Approach 1:
The patent applies preliminary action by having the driving roller continuously rotate the pressure belt at the correct speed before and during the fixing process. This eliminates the delay period where the pressure belt speed changes, as the driving force is already applied in advance through the driving roller, preventing both lag and image displacements
Solution Approach 2:
The driving roller acts as an intermediary that directly controls the pressure belt's rotation speed, decoupling it from the fixing roller's speed variations. This intermediary mechanism ensures the pressure belt maintains consistent speed regardless of slippage between the fixing roller and recording medium, preventing image displacements
3Adaptability or versatility
If the coefficient of kinetic friction between the fixing roller and recording medium decreases when large amounts of unfixed toner remain, then the conveying force of the pressure belt decreases, but this causes the recording medium to lag behind and the pressure belt to slip, resulting in poor imaging
Solution Approach 1:
The driving roller serves as an intermediary that directly drives the pressure belt, isolating the system from variations in friction between the fixing roller and recording medium. This ensures stable conveying force regardless of toner amount, as the driving roller maintains consistent frictional contact with the pressure belt
Solution Approach 2:
The patent substitutes the friction-based following movement system with a direct friction drive system. Instead of relying on friction between the fixing roller and recording medium to rotate the pressure belt, the driving roller directly friction-drives the pressure belt, providing more reliable and consistent conveying force
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 reduces image displacements and enhances image quality by maintaining consistent peripheral speeds and conveying forces, improving the gloss application and fixing process in electrophotographic image forming devices.
Implementation Method 1
the pressure belt is rotated by following movement of the fixing roller due to sliding friction force produced by sliding on the fixing roller
Implementation Method 2
a fixing apparatus for fixing an unfixed image on a recording medium
Data Source
AI summary
An image heating apparatus includes a rotatable heating member configured to heat an image on a recording medium at a nip, driving means configured to drive the heating member, an endless belt configured to form the nip with the heating member, and a driving roller configured to drive the endless belt. In the image heating apparatus, the following expressions are satisfied:μ2<μ10.005<μ2<0.3V1<V2where μ2 is a friction coefficient between the endless belt and the driving roller, μ1 is a friction coefficient between the heating member and the endless belt, V1 is a peripheral speed of the heating member, and V2 is a peripheral speed of the driving roller.