Image Forming Apparatus Trailing Edge Loop Control
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Solution Overview
Problem
Existing image forming apparatuses using electrophotographic techniques face issues with spark discharge between the trailing edge of the recording material and the fixing film, leading to image defects, and current solutions complicate the apparatus configuration with additional power supplies or air blowout units.
Innovation Solution
The apparatus employs a control unit to adjust the conveyance speed of the recording material between the fixing and conveyance units, ensuring the trailing edge is looped towards the pressure member before passing through the fixing nip, thereby preventing spark discharge without additional power or air blowout units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If air is blown toward the recording material to suppress movement of the trailing edge portion, then discharge between the trailing edge and fixing film is reduced, but the apparatus configuration becomes complex and costs increase due to additional air blowout units
Solution Approach 1:
The conveyance rollers themselves perform the function of preventing discharge by controlling the trailing edge position, eliminating the need for separate air blowout units. The system uses its existing conveyance mechanism to achieve the protective function.
Solution Approach 2:
The invention changes the conveyance speed parameter of the trailing edge relative to the fixing film speed, creating a speed difference that prevents the trailing edge from approaching the fixing film too closely, thereby preventing discharge without additional components.
2Object-affected harmful factors
If bias voltage is applied to the fixing film or pressure roller to draw away adhered toner, then image defects are prevented, but the apparatus requires additional power supply units increasing complexity and cost
Solution Approach 1:
The conveyance rollers perform the function of preventing toner adhesion by controlling the trailing edge position, eliminating the need for separate bias voltage power supplies. The existing conveyance system is utilized to achieve the protective function.
3Productivity
If the trailing edge portion is allowed to move freely, then conveyance efficiency is maintained, but discharge occurs between the trailing edge and fixing film causing image defects
Solution Approach 1:
The invention introduces a speed difference parameter between the trailing edge conveyance and the fixing film rotation, controlling the relative position to prevent discharge while maintaining efficient conveyance through optimized speed parameters.
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 effectively reduces spark discharge and maintains conveyance efficiency by adjusting the relative conveyance speeds between the fixing and conveyance units, preventing image defects without increasing the apparatus complexity.
Implementation Method 1
due to the potential difference between the recording material and the fixing film, discharge, which is so-called spark discharge, is generated at a portion of the surface of the fixing film charged negatively
Data Source
AI summary
According to one aspect of the present invention, an image forming apparatus includes a fixing unit comprising a fixing member configured to fix a toner image to a recording material, and a pressure member configured to form a first nip portion, a conveyance portion configured to form a second nip portion, and a control unit configured to execute, a conveyance mode of conveying the recording material so that the recording material is not looped between the first nip portion and the second nip portion prior to a predetermined timing during passing of the recording material of the first nip portion, and conveying the recording material so that the recording material is looped toward the pressure member from the predetermined timing until a trailing edge of the recording material has passed through the first nip portion.