Image Reading Device Conveyance Speed Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, image reading accuracy deteriorates due to conveyance unevenness, which is not effectively addressed by existing defect detection techniques, leading to potential damage and uneven gloss in printed images.
Innovation Solution
An image reading device with conveyance roller pairs disposed upstream and downstream of the image reading unit, where the controller adjusts the rotation speeds of these rollers to maintain consistent conveyance speed, preventing slack and conveyance unevenness by varying the speed difference based on detected intervals or sheet thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveyance speed is increased to improve productivity, then the output rate increases, but the image reading accuracy deteriorates due to conveyance unevenness
Solution Approach 1:
The conveyance roller pairs dynamically adjust their rotation speeds based on the detected position of the sheet. The control unit varies the rotation speed of each roller pair according to the sheet's conveyance state, allowing the system to maintain high overall productivity while ensuring accurate image reading at critical moments when the sheet passes through the reading unit.
Solution Approach 2:
The system changes the rotational speed parameter of the conveyance rollers during the conveyance process. By adjusting the rotation speed of upstream and downstream rollers differently, the system creates controlled speed variations that prevent sheet slack and maintain consistent sheet tension, thereby preserving image reading accuracy even at higher conveyance speeds.
2Stability of the object's composition
If the conveyance speed difference between upstream and downstream rollers is increased to prevent sheet slack, then the sheet tension is improved, but the conveyance uniformity deteriorates
Solution Approach 1:
Different roller pairs are assigned different rotational speeds based on their local position in the conveyance path. Upstream rollers may rotate faster to prevent slack, while downstream rollers adjust accordingly. This localized speed differentiation maintains sheet tension without compromising overall conveyance uniformity, as each roller pair performs its specific function optimally.
Solution Approach 2:
The control unit continuously monitors the sheet's conveyance state and adjusts the rotation speeds of roller pairs in real-time. Based on feedback from sheet position detection, the system optimizes the speed difference between upstream and downstream rollers, maintaining appropriate sheet tension while ensuring uniform conveyance through dynamic speed adjustment.
3Measurement precision
If the rotation speed of conveyance rollers is adjusted to maintain sheet tension, then the image reading accuracy is improved, but the device complexity increases
Solution Approach 1:
The control unit serves multiple functions: it controls the rotation speeds of multiple roller pairs, monitors sheet position, detects sheet thickness, and adjusts conveyance parameters dynamically. By consolidating these functions into a single control system, the patent manages device complexity while achieving improved image reading accuracy through coordinated roller speed adjustment.
Data Source
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Figure 3A~3B
AI summary
An image reading device (50) includes an image reading unit (80) to read an image formed on a sheet (P), a first conveyor (81) to convey the sheet (P), a second conveyor (82) to convey the sheet (P), and circuitry (150). The first conveyor (81) is disposed upstream from the image reading unit (80) in the conveyance direction of the sheet (P), and a second conveyor (82) is disposed downstream from the image reading unit (80) in the conveyance direction. The circuitry (150) controls conveyance speeds of the sheet (P) by the first conveyor (81) and the second conveyor (82) to change a difference between the conveyance speeds of the sheet (P) by the first conveyor (81) and the second conveyor (82) based on the image read by the image reading unit (80).