Image Reading Roller Speed Control for Sheet Bends
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Solution Overview
Problem
Conventional image reading apparatuses face reading failures due to fluctuations in sheet conveying speed, primarily caused by bends in the sheet and idling of rollers equipped with one-way clutches, leading to expansion and contraction of read images.
Innovation Solution
The apparatus employs a reading downstream roller pair that maintains a predetermined nip pressure and includes an idling mechanism, such as a one-way clutch, to prevent idling and stabilize the conveying speed, while also allowing the conveying force to be lowered through an idling mechanism in the outward-conveying roller pair, ensuring smooth synchronization with the post-processing apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rollers equipped with one-way clutches are used to enable sheet withdrawal after reading, then sheet conveyance flexibility is improved, but reading accuracy deteriorates due to idling and conveying speed fluctuations
Solution Approach 1:
The patent applies dynamics by making the roller's rotational characteristics changeable based on operational needs. The roller transitions from a fixed one-way clutch configuration to a dynamic system where the rotational characteristic changing mechanism can switch between one-way clutch engagement and disengagement, allowing the roller to adapt its behavior from preventing reverse rotation to free rotation as conditions require.
Solution Approach 2:
The patent changes the rotational parameter of the roller from a fixed state (one-way clutch engaged or disengaged) to a variable state. By controlling the engagement and disengagement of the one-way clutch based on sheet position and conveyance requirements, the system dynamically adjusts the roller's rotational characteristics to optimize both reading accuracy and sheet withdrawal capability.
2Productivity
If conveying speed is increased in post-processing apparatus to secure processing time, then post-processing efficiency is improved, but sheet conveyance stability deteriorates causing reading failures
Solution Approach 1:
The patent applies preliminary action by ensuring the sheet is fully read and the reading section has completed its measurement before the post-processing apparatus accelerates the sheet conveyance. The control mechanism monitors reading completion status and only permits speed increase after reading is finalized, preventing any potential reading failures caused by sudden acceleration.
Solution Approach 2:
The system uses feedback control where the reading completion status is continuously monitored and fed back to the conveyance control mechanism. Based on this feedback, the system decides when to increase conveyance speed in the post-processing apparatus, ensuring that acceleration only occurs after reading is complete and will not compromise reading 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 effectively suppresses reading failures by maintaining consistent conveying speed and preventing idling, ensuring accurate image reading and smooth acceleration of sheet conveyance, even when bends occur, thereby enhancing the reliability of the image reading process.
Implementation Method 1
each conveyance roller pair positioned on the downstream side of a reading section includes a roller equipped with a one-way clutch that can rotate only in one direction
Implementation Method 2
a reading downstream roller pair, which conveys the sheet S while maintaining a predetermined nip pressure
Data Source
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AI summary
An image reading apparatus (2) includes: a reader (202); a first conveyance roller pair (212); a second conveyance roller pair (213); and a conveying force lowering section that lowers a conveying force exerted from the second conveyance roller pair on a sheet when acceleration control for accelerating a conveying speed of the sheet whose image has been read by the reader is performed, compared with a case in which the acceleration control is not performed.