Image Reading Apparatus Staggered Sensor Conveyance Error Correction
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Solution Overview
Problem
In image reading apparatuses using multiple line image sensors, conveyance errors due to eccentricity or diameter errors in the original conveyance rollers can lead to inaccurate stitching of read data, especially when the conveyance length is shorter than one revolution of the roller.
Innovation Solution
The image reading apparatus is configured with a plurality of line image sensors arranged in a staggered manner, an upstream roller, and a downstream roller. A processor controls the apparatus to detect conveyance errors by reading a detection pattern, and it specifically uses read data from line image sensors close to the rollers to accurately determine errors in regions conveyed only by the upstream or downstream rollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple line image sensors are used to read large-format originals, then the reading capability is improved, but stitching position errors occur due to conveyance direction misalignment caused by roller eccentricity
Solution Approach 1:
The system performs calibration processing before actual reading operations to obtain error components caused by roller eccentricity and diameter errors. By pre-acquiring correction data through calibration patterns, the system compensates for conveyance errors that would otherwise affect stitching accuracy during normal operation.
Solution Approach 2:
The system uses calibration patterns with known geometric features (dots, lines, spaces) to measure actual conveyance positions and compare them against expected positions. This feedback mechanism allows the system to calculate error components and apply corrections to improve stitching accuracy in subsequent readings.
2Volume of moving object
If the conveyance length is made shorter to reduce apparatus size, then the apparatus size is reduced, but the conveyance length becomes shorter than one roller revolution, making it difficult to accurately obtain error components
Solution Approach 1:
The system transitions from relying solely on conveyance length in the reading direction to utilizing the main scanning direction (perpendicular to conveyance) for error detection. By arranging calibration patterns and line image sensors such that error components can be detected through scanning across the width rather than requiring long conveyance distances, the system achieves accurate error measurement within compact dimensions.
Solution Approach 2:
The system changes the approach to error detection by using multiple line image sensors arranged in a main scanning direction rather than relying on a single sensor requiring long conveyance. This parameter change in sensor arrangement allows error components to be captured through the scanning mechanism itself, eliminating the need for conveyance lengths exceeding one roller revolution.
3Ease of operation
If line image sensors are arranged in a straight line, then conveyance errors act uniformly on all sensors, but misalignment among sensors in the conveyance direction causes differential conveyance errors that worsen stitching position accuracy
Solution Approach 1:
The system deliberately arranges line image sensors in a staggered configuration rather than a straight line, creating asymmetric positioning that allows differential conveyance errors to be detected and corrected. This asymmetric arrangement, combined with calibration processing, enables the system to measure and compensate for position-dependent conveyance variations.
4Manufacturing precision
If calibration is performed to obtain error components from roller eccentricity and diameter errors, then stitching accuracy is improved, but additional processing time and complexity are introduced
Solution Approach 1:
The system combines multiple error detection functions into a single calibration processing step that simultaneously measures error components from roller eccentricity, diameter errors, and sensor misalignment. By using calibration patterns containing multiple feature types (dots, lines, spaces) and processing them together, the system achieves comprehensive error characterization in one operation rather than requiring separate measurements.
Data Source
AI summary
An image reading apparatus includes a plurality of line image sensors, an upstream roller disposed upstream from the plurality of line image sensors, a downstream roller disposed downstream from the plurality of line image sensors, and a control unit that, in a case where detecting conveyance error by using the plurality of line image sensors, performs control such that in a first region of an original conveyed only by the upstream roller, the conveyance error is detected using read data from a line image sensor that is disposed close to the upstream roller, and in a third region of the original conveyed only by the downstream roller, the conveyance error is detected using read data from a line image sensor that is disposed close to the downstream roller.