Image Forming Apparatus Fixing Nip Speed Control
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Solution Overview
Problem
In image forming apparatuses, the close proximity of transfer and fixing nip portions leads to issues with curled recording materials, causing defective images due to increased rigidity and loop cancellation forces, especially when handling thicker materials like cardboard, resulting in image disturbances and defects.
Innovation Solution
An image forming apparatus with a loop amount detection device and control system that adjusts the conveyance speed of the fixing nip portion to maintain a predetermined loop range, and further controls the speed to ensure the recording material touches a guide member before exiting the transfer nip portion, stabilizing the trailing edge and preventing image defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between transfer nip portion and fixing nip portion is reduced, then the apparatus size is reduced, but the recording material trailing edge bounces and causes defective images
Solution Approach 1:
The patent applies dynamics by making the conveyance speed of the fixing nip portion variable rather than constant. The control unit dynamically adjusts the conveyance speed based on the loop amount detected by the detection device, allowing the system to adapt to different recording material conditions and prevent trailing edge bouncing while maintaining compact dimensions
Solution Approach 2:
The patent implements feedback control by using a detection device to monitor the loop amount of the recording material and feeding this information back to the control unit. The control unit then adjusts the conveyance speed of the fixing nip portion accordingly, creating a closed-loop control system that prevents defective images while maintaining compact apparatus size
2Stability of the object's composition
If the conveyance speed of fixing nip portion is increased to prevent sagging, then loop control is improved, but the recording material trailing edge bounces and causes defective images
Solution Approach 1:
The patent makes the conveyance speed dynamic by adjusting it based on the detected loop amount. Instead of using a fixed high speed that causes bouncing, the system dynamically modulates the speed to maintain appropriate loop formation without excessive tension, preventing trailing edge bouncing while maintaining loop control
Solution Approach 2:
The patent changes the parameter of conveyance speed based on the loop amount detection. By varying the conveyance speed parameter in response to detected loop conditions, the system prevents both sagging and trailing edge bouncing, resolving the contradiction between loop control stability and image quality
Data Source
AI summary
The image forming apparatus, a conveyance speed of a recording material at a fixing nip portion, controlled by a control portion of the image forming apparatus so that a part of the recording material being conveyed touches a guide member between a transfer nip portion and a loop detection device for a period after an operation for maintaining a loop amount of the recording material being conveyed within a predetermined range is finished until the recording material trailing edge exits out the transfer nip portion.