Image Reading Apparatus Dual Mode Sub-Scanning Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately detecting geometric characteristics like printing position misregistration due to variations in sub-scanning magnification caused by differences in sheet type, basis weight, and surface properties, which affects the accuracy of correction values for duplex printing.
Innovation Solution
The apparatus employs a dual reading mode system, using both a conveyance unit and a platen to read test images on a sheet, allowing for the calculation of correction values based on images read in both modes to adjust conveying speed and correct sub-scanning magnification, thereby improving the accuracy of printing position alignment on both surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single reading mode (ADF conveyance) is used to read test images, then reading efficiency is improved, but measurement precision of geometric characteristics deteriorates due to sub-scanning magnification variation
Solution Approach 1:
The reading process is segmented into two distinct modes: ADF conveyance reading and platen reading. Each mode serves a specific purpose - ADF reading captures images during conveyance for efficiency, while platen reading provides a reference without conveyance-induced distortion. This segmentation allows the system to leverage the strengths of both modes while mitigating their individual weaknesses.
Solution Approach 2:
The platen reading acts as an intermediary reference that mediates between the ADF conveyance reading and the ideal geometric characteristics. By comparing ADF readings against platen readings (which are not affected by conveyance speed variation), the system can calculate correction values that compensate for sub-scanning magnification errors, thus achieving both efficiency and precision.
2Device complexity
If a fixed sub-scanning magnification correction value is used for all sheet types, then device complexity is reduced, but measurement precision deteriorates due to sheet type variations
Solution Approach 1:
The system dynamically changes the sub-scanning magnification correction value based on detected sheet characteristics. Instead of using a fixed correction value, the system adjusts the correction parameter according to the actual sheet type, basis weight, and surface properties detected during reading, thereby maintaining high precision across different sheet types without requiring manual configuration for each type.
Solution Approach 2:
The system performs self-calibration by automatically detecting sheet characteristics and adjusting correction values without external intervention. The image reading apparatus itself generates the correction data by comparing ADF and platen readings, eliminating the need for manual correction value entry or complex pre-configuration for different sheet types.
3Productivity
If ADF conveyance speed is controlled to maintain reading efficiency, then productivity is improved, but measurement precision deteriorates due to conveying speed variation
Solution Approach 1:
The system implements feedback by continuously monitoring the actual conveyance speed during ADF operation and using this information to adjust correction values. The comparison between ADF readings and platen readings provides feedback on the actual magnification error, which is then used to correct subsequent readings, maintaining precision even when conveyance speed varies to maintain high productivity.
Data Source
AI summary
An image reading apparatus includes a tray on which a sheet is to be placed, a conveyance unit configured to convey the sheet placed on the tray, a platen on which a sheet is to be placed, a reading unit configured to read one of a first surface of the sheet conveyed by the conveyance unit and a first surface of the sheet placed on the platen, and a controller configured to control the image reading apparatus to execute, a first reading mode of reading, by the reading unit, a first surface of a sheet having a plurality of test images formed thereon, which is conveyed by the conveyance unit; and a second reading mode of reading, by the reading unit, the first surface of the sheet having the plurality of test images formed thereon, which is placed on the platen.