Fixing Device Pressurizing Member Segmentation for Envelope Crease Prevention
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Solution Overview
Problem
Conventional fixing devices in image forming apparatuses often generate creases on specific recording media like envelopes due to uneven pressure distribution and speed differences during the fixation process, leading to suboptimal image formation and potential fixing failures.
Innovation Solution
A fixing device with a pressurizing member comprising a hard pressurizing member and a soft pressurizing member, where the hard member is positioned downstream and has a higher hardness than the elastic layer of the heating roll, and the soft member is positioned upstream with lower hardness, both disposed to maintain a specific clearance to ensure even pressure distribution and reduce crease generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressurizing member is used, then the device complexity is reduced, but the pressure distribution becomes uneven causing creases on envelopes
Solution Approach 1:
The pressurizing member is divided into two distinct segments: a hard pressurizing member (protruding portion) and a soft pressurizing member (pad portion). This segmentation allows each part to perform different functions - the hard portion provides structural support and positioning, while the soft portion ensures uniform pressure distribution through elastic deformation, thereby preventing creases on envelopes without significantly increasing overall device complexity.
Solution Approach 2:
Different regions of the pressurizing member are assigned different material properties: the protruding portion uses a hard material for rigidity and positioning, while the pad portion uses a soft material for conformal pressure application. This local differentiation of material quality enables the pressurizing member to simultaneously maintain structural integrity and achieve uniform pressure distribution across the recording medium surface.
2Stability of the object's composition
If only a hard pressurizing member is used, then the pressure contact is stable, but creases are generated on specific recording media like envelopes
Solution Approach 1:
The invention changes the material parameter (hardness) of the pressurizing member by incorporating both hard and soft materials in different regions. The soft pad portion can elastically deform to adapt to the surface characteristics of specific recording media like envelopes, reducing crease generation while the hard protruding portion maintains stable pressure contact positioning. This parameter differentiation resolves the contradiction between stability and crease prevention.
3Object-affected harmful factors
If only a soft pressurizing member is used, then crease generation is reduced, but the pressure contact position becomes unstable
Solution Approach 1:
The pressurizing member is segmented into a hard protruding portion that provides stable positioning and a soft pad portion that prevents creases. The hard segment acts as a stable anchor point maintaining consistent pressure contact position, while the soft segment conforms to the recording medium surface to eliminate creases, thus resolving the contradiction between stability and crease prevention.
4Stress or pressure
If the pressurizing members are in direct contact, then the pressure distribution is maximized, but thick papers cannot pass through properly
Solution Approach 1:
The invention applies local quality differentiation where the hard protruding portion provides structural support and positioning, while the soft pad portion provides conformal pressure application. This local differentiation allows the pressure contact portion to maintain effective pressure distribution for image fixation while the overall structure accommodates thick papers by allowing the soft portion to compress and the clearance to be maintained, thus resolving the contradiction between pressure maximization and passage efficiency.
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 prevents crease formation on envelopes and other thick papers by maintaining a consistent pressure contact, enhancing image formation quality and fixing performance without creases or fixing failures.
Implementation Method 1
a heating roll that includes an outer peripheral surface having an elastic layer formed thereon and is heated by a heating unit and is rotated
Implementation Method 2
a soft pressurizing member disposed in a position on an upstream side in the passing direction from the hard pressurizing member and having a lower hardness than that of the elastic layer of the heating roll to carry out an elastic deformation
Data Source
AI summary
A fixing device comprises a heating roll; an endless belt; and a pressurizing member that forms a pressure contact portion for pushing the endless belt against an outer peripheral surface part of the heating roll from an inner peripheral surface side of the pressurizing member so that a recording medium holding an unfixed image passes between the pressure contact portion and the heating roll, wherein the pressurizing member includes: a hard pressurizing member and a soft pressurizing member the hard pressurizing member, and the soft pressurizing member are disposed in a state in which a clearance is present between the hard pressurizing member and the soft pressurizing member in a specific region part so that at least a specific recording medium passes in a fixing region of the pressure contact portion in the rotating axis direction of the heating roll.