Fixing Belt Surface Restoration via Differential Speed Control
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Solution Overview
Problem
Existing image forming apparatuses face issues with gloss lines on images due to rough surfaces of fixing belts when handling thick or rough sheets, leading to uneven image fixation and reduced shine on fixed images.
Innovation Solution
The implementation of a control system that adjusts the rotational speed of the braking force generation motor and assist force generation motor to create a differential circumferential speed between the fixing belt and pressure roller, allowing for effective braking and assist forces to restore the fixing belt surface and prevent gloss lines, while maintaining motor speed within safe limits to avoid overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a braking force is applied to the fixing belt to restore its surface by creating differential circumferential speed between the fixing belt and pressure roller, then the gloss line problem is solved and image fixation uniformity is improved, but the braking motor generates excessive heat and cannot operate continuously
Solution Approach 1:
The patent implements periodic restore control where the braking motor operates intermittently rather than continuously. The control unit activates the braking motor to generate differential circumferential speed between the fixing belt and pressure roller only during non-fixing periods, creating periodic surface restoration cycles. This allows the motor to cool down between operations, preventing excessive heat accumulation while still effectively removing gloss lines and maintaining image fixation uniformity.
2Manufacturing precision
If the braking motor operates continuously to maintain fixing belt surface quality, then gloss lines are prevented, but productivity decreases due to extended restore control time
Solution Approach 1:
The system performs surface restoration periodically during non-fixing periods rather than continuously during fixing operations. The control unit schedules restore control cycles when no images are being formed, allowing the braking motor to operate briefly to restore the fixing belt surface, then cease operation to maximize productivity. This periodic approach maintains surface quality while minimizing impact on image formation throughput.
Solution Approach 2:
The restore control is performed in advance during non-fixing periods before the next image formation sequence begins. By proactively restoring the fixing belt surface during idle time, the system ensures optimal surface quality is maintained for upcoming fixing operations without interrupting or delaying image formation, thus preserving productivity while achieving surface quality goals.
3Manufacturing precision
If differential circumferential speed is created between fixing belt and pressure roller to restore surface, then gloss lines are removed, but the mechanism complexity increases due to additional motor control requirements
Solution Approach 1:
The braking motor serves dual functions: it acts as a braking force generation motor during restore control to create differential circumferential speed for surface restoration, and as an assist force generation motor during normal fixing operations to maintain synchronous rotation. The control unit switches between these modes based on operational requirements. This multi-functionality reduces the need for separate dedicated motors for each function, thereby limiting the increase in mechanism complexity while still achieving effective surface restoration.
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 removes gloss lines by restoring the fixing belt surface and ensuring uniform image fixation, preventing heat generation in the braking motor, and maintaining productivity by shortening the restore control time.
Implementation Method 1
create a differential circumferential speed between the fixing belt and pressure roller, allowing for effective braking and assist forces to restore the fixing belt surface
Data Source
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AI summary
A fixing apparatus comprises a fixing nip width adjustment unit (68) configured to adjust the fixing nip width "d" of a fixing nip portion (NP); a braking force generation motor (M1) configured to generate an effective braking force in the direction to hinder rotation of an upper pressure roller (63); and a control unit (100) configured to perform restore control for rotating the upper pressure roller (63) and a lower pressure roller by driving a drive motor (M3) and speed keeping control for keeping the rotational speed of the braking force generation motor (M1) no higher than a predetermined speed during the restore control in a non-fixing period in which the fixing nip width adjustment unit (68) is controlled to decrease the fixing nip width "d" smaller than in a fixing period and a braking force is applied to the upper pressure roller (63) by the braking force generation motor (M1).