Fixing Belt Position Control via Steering Roller Dynamics
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Solution Overview
Problem
In image forming apparatuses, the reduction of space between the transfer nip and fixing nip to less than the paper width can lead to paper distortion, causing poor image forming conditions and reduced productivity due to the need for frequent belt position adjustments during the image forming process.
Innovation Solution
An image forming apparatus with a fixing belt position changing mechanism and a control unit that adjusts the widthwise position of the fixing belt only when the paper is not nipped by both the transfer nip and the fixing nip simultaneously, using a steering roller to change the rotation angle and maintain optimal belt alignment without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the space between transfer nip and fixing nip is reduced to less than paper width for downsizing, then compactness is improved, but paper distortion occurs causing poor image forming conditions
Solution Approach 1:
The patent applies dynamics by making the roller angles adjustable rather than fixed. The control unit dynamically changes the angles of rollers (such as roller 213 in transfer unit 210 and roller 223 in fixing unit 220) based on detected belt position displacements. This allows the system to adapt to varying conditions and maintain proper image forming quality even in the compact configuration where paper passes through both nips simultaneously.
2Measurement precision
If belt position control is performed by angle control of roller when paper is nipped by both transfer nip and fixing nip simultaneously, then belt position accuracy is improved, but paper distortion occurs
Solution Approach 1:
The patent implements feedback control where a detection device (such as light receiver 66 detecting position of fixing belt 62) continuously monitors belt position, and the control unit adjusts roller angles based on this feedback. However, the control unit includes logic to determine whether paper is present in the nip region before executing angle adjustments. When paper is detected in the nip, the control unit suppresses angle changes to prevent distortion, while still maintaining belt position accuracy by making adjustments only when appropriate.
Solution Approach 2:
The patent applies local quality by making different parts of the system (rollers at different positions) have different adjustable properties. Specifically, the control unit can independently adjust the angles of different rollers (e.g., roller 213 in transfer unit and roller 223 in fixing unit) with different ranges and characteristics, allowing precise local control of belt position without affecting the entire system uniformly, thereby preventing paper distortion while maintaining accuracy.
3Measurement precision
If frequent belt position adjustments are made during image forming process, then belt alignment accuracy is improved, but productivity is reduced due to downtime
Solution Approach 1:
The control unit continuously monitors belt position through detection devices and makes real-time angle adjustments of rollers based on detected deviations. This feedback mechanism maintains belt alignment accuracy during the image forming process without requiring frequent interruptions or downtime for manual adjustments, thereby preserving productivity while ensuring consistent alignment.
Solution Approach 2:
The patent ensures continuous operation by implementing automatic roller angle adjustment during the image forming process. Instead of stopping production to make belt position corrections, the control unit continuously monitors and adjusts roller angles on-the-fly, maintaining belt alignment while the image forming process continues uninterrupted, thus preserving productivity.
4Stability of the object's composition
If guide members are provided at both side portions of belt to inhibit position displacement, then belt position stability is improved, but belt can still go over guide members when greatly displaced reducing reliability
Solution Approach 1:
The patent replaces static guide members with dynamic roller angle adjustment. Instead of relying on fixed guide members that can be overcome when belt displacement is large, the control unit dynamically changes roller angles to actively guide and correct belt position. This dynamic approach maintains stability while preventing the belt from going over guide members, even when large displacements occur, thereby improving reliability.
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 prevents paper distortion and maintains high productivity by minimizing the need for belt position corrections during the image forming process, ensuring consistent image quality and reducing downtime for adjustments.
Implementation Method 1
The fixing belt position changing mechanism unit includes a first steering roller to extend the fixing belt and the fixing belt position changing mechanism unit changes the widthwise position of the fixing belt by changing a rotation angle of the first steering roller
Data Source
AI summary
Provided is an image forming apparatus comprising a secondary transfer belt disposed at a position to face an intermediate transfer belt across the transfer passage of paper (P), a fixing belt disposed on the down-stream side of the secondary transfer belt in the transfer direction of the paper (P) and at a position to face a rotary fixing member across the transfer passage of the paper (P), a photo sensor for detecting the widthwise position of the fixing belt, a steering roller angle changing unit for making the rolling angle of a steering roller changeable, and a first control unit for controlling a stepping motor on the basis of the signal of the photo sensor. The control unit does not perform the angle change of the steering roller, if the paper is constricted by both a transfer nip and a fixing nip.