Fixing Device Preventing Member Film Shifting Control
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Solution Overview
Problem
The existing fixing devices in image forming apparatuses face challenges with film shifting, leading to issues like film end portion breakage and unstable traveling loci due to increased shifting forces, which affect image quality and durability.
Innovation Solution
A fixing device with a cylindrical film and a preventing member having a specific contact region configuration, including a first region downstream of the nip center line and a second region upstream, where the preventing surface retracts from the film end surface, and the second region extends continuously from upstream to downstream with varying lengths to manage shifting forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the flange contacts both the inner peripheral surface and end surface of the film to prevent shifting, then film position stability is improved, but film end portion breakage occurs due to increased shifting forces
Solution Approach 1:
The preventing member is divided into two distinct functional regions: a guiding surface region that contacts the inner peripheral surface of the film to guide rotation, and a preventing surface region that contacts the end surface to prevent longitudinal movement. This segmentation allows each region to perform its specific function without creating excessive stress concentration at the film end portion.
Solution Approach 2:
Different surfaces of the preventing member are designed with different contact characteristics: the guiding surface provides rotational guidance through contact with the inner peripheral surface, while the preventing surface prevents longitudinal movement through contact with the end surface. This local differentiation of contact quality optimizes the distribution of forces on the film.
2Stability of the object's composition
If the flange prevents film movement in the longitudinal direction, then film shifting is reduced, but end portion folding occurs due to contact in regions where the guiding surface does not contact the inner peripheral surface
Solution Approach 1:
The preventing member is segmented into a guiding surface portion and a preventing surface portion. The guiding surface is positioned to contact the inner peripheral surface of the film in the upstream region, while the preventing surface contacts the end surface. This spatial segmentation ensures that the film is properly guided before the end surface contacts the preventing surface, preventing folding.
Solution Approach 2:
The guiding surface is positioned upstream of the preventing surface along the recording material feeding direction. This preliminary guidance action occurs before the film end surface contacts the preventing surface, ensuring the film is properly aligned and preventing folding from occurring when the preventing surface engages.
3Strength
If the film thickness is increased to prevent breakage, then film strength is improved, but device complexity and power consumption increase
Solution Approach 1:
Instead of changing the film thickness parameter, the invention changes the geometric parameters of the preventing member (the flange). By optimizing the shape, position, and dimensions of the preventing member, the film can maintain its original thickness while still preventing breakage through proper force distribution.
4Measurement precision
If the flange contacts the inner peripheral surface and end surface of the film, then film position control is improved, but image quality deteriorates due to unstable traveling locus
Solution Approach 1:
The preventing member is divided into a guiding surface for rotational guidance and a preventing surface for longitudinal position control. This segmentation allows independent optimization of each function: the guiding surface ensures stable rotational travel, while the preventing surface maintains precise longitudinal position, together achieving both position control precision and image quality reliability.
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 reduces shifting forces, prevents film end portion breakage, and stabilizes the film traveling locus, enhancing image quality and extending the film's durable lifetime.
Implementation Method 1
a ceramic heater contacting an inner surface of the film... In the nip, a recording material on which a toner image is carried is heated while being fed, so that the toner image is fixed on the recording material
Data Source
AI summary
A fixing device includes a cylindrical film a pressing member, and a preventing member including a preventing surface configured to prevent movement of the film in a longitudinal direction, and a film rotation guiding surface. As viewed in the longitudinal direction of the film, the preventing surface includes first and second regions positioned downstream and upstream, respectively, of a nip center line with respect to a recording material feeding direction. The first region retracts from a longitudinal film end surface relative to the second region. The second region continuously extends in the recording material feeding direction from a portion upstream of the nip center line to a portion downstream of the nip center line, and has a length, with respect to a rotational direction of the film, that is greater at the portion upstream of the nip center line than at the portion downstream of the nip center line.