Cleaning Sheet Shifting for Rotatable Heating Member
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Solution Overview
Problem
In electrophotographic image forming apparatuses, sheets with heavy calcium carbonate filler cause triboelectric charging, leading to electrostatic attraction of toner to heating members, resulting in image defects due to incomplete cleaning of rotatable heating members, especially at the widthwise ends.
Innovation Solution
An image forming apparatus with a sheet shifting mechanism that changes the positional relationship of sheets relative to the rotatable heating member during the cleaning mode, ensuring effective cleaning by shifting the sheets' position to cover the entire width, including the ends, using a cleaning sheet with a predetermined toner image formed on it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cleaning sheet is simply introduced into the nip during cleaning mode, then the cleaning process is simple and quick, but the cleaning effect is insufficient especially at the widthwise end portions of the rotatable heating member
Solution Approach 1:
The invention introduces a sheet shifting mechanism that dynamically adjusts the widthwise position of the cleaning sheet during the cleaning process. The sheet position is changed between different cleaning passes, allowing the cleaning sheet to progressively cover and clean different regions of the rotatable heating member, including the previously unreachable widthwise end portions.
Solution Approach 2:
The cleaning process is divided into multiple periodic passes through the nip. In each pass, the cleaning sheet is positioned at a specific widthwise location, and the sheet shifting mechanism adjusts the position for subsequent passes. This periodic action with position variation ensures comprehensive cleaning of the entire heating member surface.
2Reliability
If the sheet position during cleaning mode is fixed, then the cleaning process is simple to control, but the widthwise end portions of the rotatable heating member cannot be properly cleaned
Solution Approach 1:
The sheet shifting mechanism is pre-configured with predetermined shift amounts and directions for each cleaning pass. The control system automatically executes the sequence of position adjustments without requiring manual intervention, preparing the sheet position in advance for each pass to ensure comprehensive cleaning coverage.
Solution Approach 2:
The cleaning system performs self-positioning through the automated sheet shifting mechanism. The control unit automatically manages the complex position adjustments and multi-pass sequencing, making the system operate autonomously without requiring complex manual operation while achieving complete cleaning coverage.
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 solution ensures thorough cleaning of the rotatable heating member, reducing image defects by effectively removing toner accumulation from both the contact region and the widthwise ends, thereby maintaining image quality.
Implementation Method 1
a rotatable heating member and a rotatable pressing member for fixing, at a nip, the toner image-formed on the sheet
Implementation Method 2
by using a depositing force between toners (toner particles), the accumulated toner is transferred onto a solid image portion of the cleaning sheet
Implementation Method 3
the sheet powder is liable to be electrostatically attracted to a surface of the rotatable heating member
Data Source
AI summary
An image forming apparatus includes an executing portion for cleaning a rotatable heating member by introducing, into a nip, sheets, of a plurality of sheets, on which a predetermined toner image is formed by an image forming portion, a changing mechanism for making positional relationships of first and second sheets, of the plurality of sheets, relative to the rotatable heating member, different from each other with respect to a widthwise direction of the rotatable heating member when the first and second sheets are successively introduced into the nip in a cleaning mode, and a re-introducing mechanism for re-introducing the first and second sheets into the nip, the first and second sheets having passed through the nip and having been turned upside down, wherein the changing mechanism changes the relative positional relationship of the first and second sheets, which are turned upside down, relative to the rotatable heating member.