Dynamic Roller Engagement for Thick Sheet Conveyance
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Solution Overview
Problem
Conventional sheet conveyance apparatuses in image forming systems face challenges in conveying thick sheets like paperboard and cardboard, leading to potential edge curl and quality degradation due to roller contact, especially when disengaging the first roller pair does not prevent soiling and scratches effectively.
Innovation Solution
The system employs a first roller pair that transitions between contact and separated states, with controlled rotational speeds for the first and second roller pairs, decelerating the second roller pair to prevent edge curl and maintain image quality for thick sheets, while maintaining productivity for regular sheets by adjusting conveyance speeds and modes based on sheet thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the first roller pair is disengaged to prevent soiling and scratches, then image quality is improved, but edge curl occurs on thick sheets leading to quality degradation
Solution Approach 1:
The roller pair engagement state is dynamically adjusted based on sheet thickness. For thick sheets, the first roller pair remains engaged to support the trailing edge and prevent edge curl. For regular sheets, the first roller pair is disengaged to prevent soiling and scratches. This dynamic adaptation resolves the contradiction by making the system flexible rather than fixed.
Solution Approach 2:
The engagement parameter of the roller pair is changed based on sheet thickness detection. When sheet thickness exceeds a threshold, the system switches from disengaged state to engaged state for the first roller pair, thereby changing the physical contact parameter to prevent edge curl while maintaining the ability to prevent soiling through controlled engagement timing.
2Manufacturing precision
If the first roller pair remains in contact state for thick sheets, then edge curl is prevented, but soiling and scratches may occur on regular sheets
Solution Approach 1:
The system dynamically switches the engagement state of the first roller pair based on detected sheet thickness. For thick sheets requiring support, the roller pair remains engaged. For regular sheets, the roller pair is disengaged to prevent contact-related damage. This dynamic control resolves the contradiction by adapting the mechanical contact state to the specific sheet being processed.
Solution Approach 2:
The sheet thickness is detected in advance before the sheet reaches the roller pairs, allowing the system to pre-adjust the engagement state of the first roller pair. This preliminary action ensures that the correct engagement state is established before processing begins, preventing both edge curl on thick sheets and soiling on regular sheets.
3Manufacturing precision
If the second roller pair decelerates for thick sheets, then edge curl is prevented, but productivity decreases
Solution Approach 1:
The rotational speed of the second roller pair is dynamically adjusted based on sheet thickness. For thick sheets, the roller pair decelerates to reduce edge curl. For regular sheets, the roller pair maintains higher speed to preserve productivity. This dynamic speed control resolves the contradiction by adapting the conveyance speed to the specific sheet type being processed.
4Productivity
If the first roller pair is disengaged for regular sheets, then productivity is maintained, but edge curl may occur on thick sheets
Solution Approach 1:
Sheet thickness is detected in advance, allowing the system to pre-determine the appropriate engagement state of the first roller pair. This preliminary detection and decision-making enable the system to optimize both productivity and image quality for each sheet type without compromising either parameter.
Solution Approach 2:
The engagement state of the first roller pair is dynamically switched based on sheet thickness detection results. For regular sheets, the roller pair is disengaged to maintain productivity. For thick sheets, the roller pair is engaged to prevent edge curl. This dynamic adaptation resolves the contradiction by making the system responsive to actual sheet characteristics.
Data Source
AI summary
An image forming apparatus includes a first roller pair including a first roller and a second roller, a first driving unit, a second roller pair, a second driving unit, an image forming unit, and a control unit configured to execute a first mode and a second mode. The second mode includes (1) a first processing, (2) a second processing, and (3) a third processing of controlling the first driving unit such that the rotational speed of the first roller pair becomes faster than the second rotational speed. The first mode includes (1) a fourth processing, (2) a fifth processing, and (3) a sixth processing of controlling the first driving unit such that the rotational speed of the first roller pair is decelerated from the first rotational speed to equal to or less than the second rotational speed.