Fixing Device Nip Width Control for Surface Restoration
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Solution Overview
Problem
Existing electrophotographic image forming apparatuses face issues with gloss unevenness due to sheet-edge marks left on fixing devices, particularly when handling thick or rough sheets, and existing solutions either fail to ensure smooth surface slipping between fixing components or require additional costly restoration devices.
Innovation Solution
A fixing device with a control system that adjusts the fixing nip width and rotates the fixing side and back side supporting members at different circumferential speeds to restore the surface, ensuring sufficient sliding contact and preventing gloss unevenness without increasing costs by eliminating the need for separate restoration devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed difference is provided between fixing member and pressing member to enable sliding contact for surface cleaning, then sheet-edge mark removal is improved, but sufficient rubbing may not be achieved depending on fixing nip state, resulting in unreliable gloss unevenness prevention
Solution Approach 1:
The fixing nip width is made dynamically adjustable rather than fixed. The control section changes the fixing nip width to different values at different time points during operation, enabling the system to adapt to different operational requirements (image fixing vs. surface restoration) and ensure reliable surface cleaning effectiveness.
Solution Approach 2:
The patent changes the parameter of fixing nip width to control the operational mode. By adjusting the fixing nip width parameter, the system transitions between image fixing mode and surface restoration mode, thereby controlling the circumferential speed difference and enabling reliable surface restoration without requiring additional complex mechanisms.
2Reliability
If a dedicated restoring section is provided to restore surface property of fixing roller, then surface restoration is improved, but device cost increases
Solution Approach 1:
The fixing device is designed to perform multiple functions: both image fixing and surface restoration. By controlling the fixing nip width and circumferential speed difference, the same fixing device structure accomplishes surface restoration without requiring a separate dedicated restoring section, thereby reducing device complexity and cost while maintaining restoration capability.
Solution Approach 2:
The patent merges the surface restoration function into the existing fixing device structure. The fixing member and pressing member, originally designed for image fixing, are made to also perform surface restoration by adjusting operational parameters (fixing nip width and speed difference), eliminating the need for separate restoration components.
3Reliability
If fixing nip width is reduced to enable smooth slipping between surfaces, then surface restoration effectiveness is improved, but image fixing performance may be affected
Solution Approach 1:
The system performs operations in periodic cycles: image fixing operations alternate with surface restoration operations. During image fixing, the fixing nip width is set to a first value optimized for fixing quality; during surface restoration, it is set to a second value optimized for surface cleaning. This periodic switching ensures both image quality and surface restoration effectiveness.
Solution Approach 2:
The fixing nip width is dynamically adjusted based on the operational phase. The control section changes the fixing nip width to different values at different time points, enabling the system to optimize for image fixing during printing operations and for surface restoration during maintenance cycles, thereby maintaining both image quality and restoration effectiveness.
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 removes sheet-edge marks and prevents gloss unevenness by ensuring desired speed differences and sliding contact between fixing components, maintaining image quality without additional costly equipment.
Implementation Method 1
rotate the fixing side member and the back side supporting member at different circumferential speeds so as to restore a surface of the fixing side member
Data Source
AI summary
Disclosed herein is a fixing device including: a fixing nip width changing section configured to change a fixing nip width of a fixing nip; and a control section configured to control the fixing nip width changing section such that the fixing nip width is smaller than a fixing nip width for use in a fixation, and to rotate a fixing side member and a back side supporting member at different circumferential speeds so as to restore a surface of the fixing side member, wherein the control section controls the fixing nip width such that a circumferential speed difference between the fixing side member and the back side supporting member is equal to a predetermined circumferential speed difference.