Adjustable Roller for Sheet Flapping in Image Scanners
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Solution Overview
Problem
Existing image reading systems face issues with sheet conveyance troubles and flapping during image reading, particularly due to varying sheet stiffness, which affects reading performance and accuracy.
Innovation Solution
An image reading apparatus with a scanner, calibration member, and adjustable second roller that varies its position based on sheet stiffness, combined with a loading unit and conveyance units, ensures the sheet is pressed and guided within the scanner's reading performance range, reducing flapping and conveyance troubles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheet is passed through a gap without pressing, then conveyance troubles are inhibited, but the sheet flaps in the reading position causing reading errors
Solution Approach 1:
The second roller is positioned at a variable location that changes according to the stiffness of the medium. For stiff media, the roller is positioned closer to the scanner to provide pressing force, while for flexible media, it is positioned farther away. This dynamic adjustment resolves the contradiction by adapting the pressing action to the specific medium properties, ensuring both reliable conveyance and stable reading position.
2Measurement precision
If a sheet passing through a gap is pressed, then reading accuracy is improved, but conveyance troubles increase as sheet stiffness increases
Solution Approach 1:
The pressing force is applied locally at the second roller position, which is specifically located in the region where the medium passes between the scanner and calibration member. This localized pressing ensures that only the necessary area is pressed to prevent flapping during reading, while avoiding excessive pressing that would cause conveyance troubles. The local quality principle allows differential treatment of different regions of the medium path.
Solution Approach 2:
The position parameter of the second roller is changed according to the stiffness of the medium. By adjusting the roller position parameter, the system adapts the pressing force application to match the medium's mechanical properties, achieving optimal balance between preventing flapping and avoiding conveyance troubles for each type of medium.
3Device complexity
If the second roller position is fixed, then device complexity is reduced, but reading performance cannot be guaranteed for all medium stiffness levels
Solution Approach 1:
The system employs a variable position second roller that can be adjusted to different locations along the medium path. This dynamic positioning capability, while adding some complexity, ensures that reading performance is maintained across different medium stiffness levels by optimizing the pressing position for each specific medium type.
Data Source
AI summary
An image reading apparatus includes a scanner structured to reads an image formed on a medium which is conveyed; a calibration member located opposite to the scanner and structured to reflect irradiation light to be radiated to the medium when reading an image; a first roller arranged in a fixed position and structured to guide a conveying direction of the medium passing between the scanner and the calibration member; and a second roller arranged in a variable position in accordance with the stiffness of the medium and structured to guide the conveying direction of the medium passing between the scanner and the calibration member.