Document Conveyance Guide Mechanism for Inclination Correction
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Solution Overview
Problem
Image reading devices face challenges in accurately detecting and correcting document inclination during the scanning process, leading to potential image distortion and incomplete copies, especially with long documents.
Innovation Solution
The implementation of a multifunction apparatus with a document conveyance system equipped with detection sensors and guide members that adjust the document's position and conveyance path to ensure accurate alignment and correction of document inclination, using both 'center guide' and 'corner guide' mechanisms, and employing image processing techniques to generate inclination-corrected image signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single guide mechanism is used for document conveyance, then the device complexity is reduced, but the manufacturing precision of document alignment deteriorates for long documents
Solution Approach 1:
The patent implements a dynamic guide mechanism that automatically switches between corner guide mode and center guide mode based on document length detection. For long documents, the corner guide is activated to maintain alignment precision, while for standard documents, the center guide operates. This dynamic adaptation resolves the contradiction by adjusting the guide configuration according to actual document characteristics rather than using a fixed single-mode structure.
Solution Approach 2:
The guide mechanism is segmented into functionally independent corner guide and center guide subsystems. The corner guide includes front and rear guides positioned at document edges, while the center guide includes side guides positioned at document center. This segmentation allows selective activation of appropriate guide elements based on document type, enabling high alignment precision for both long and standard documents without requiring a single complex unified structure.
2Device complexity
If document inclination detection is performed at a single position, then the device complexity is reduced, but the measurement precision of inclination angle deteriorates
Solution Approach 1:
The patent places detection sensors at multiple specific positions: front edge detection sensors at the leading edge, rear edge detection sensors at the trailing edge, and intermediate position sensors along the document path. Each sensor location provides localized inclination measurement data. This multi-position arrangement improves overall inclination measurement precision by capturing variation across the document rather than relying on a single measurement point, while keeping each individual sensor simple.
3Device complexity
If the document conveyance path is fixed, then the device complexity is reduced, but the adaptability to different document lengths deteriorates
Solution Approach 1:
The conveyance path is designed with dynamic adjustability through movable guide members and adjustable sensor positions. The corner guide and center guide can be selectively activated based on detected document length. For long documents, the corner guide engages to provide an extended conveyance path suitable for maintaining alignment over greater distances. For standard documents, the center guide operates with a shorter effective path. This dynamic reconfiguration enables the fixed physical structure to adapt to variable document lengths.
4Productivity
If image reading is performed without inclination correction, then the processing speed is increased, but the manufacturing precision of image output deteriorates
Solution Approach 1:
The system performs preliminary inclination detection and correction before the main image reading and processing operations. Detection sensors measure document inclination at multiple positions along the conveyance path, and correction mechanisms adjust the document orientation or compensate for inclination in the captured image data before final processing. This preliminary correction ensures high image output quality without significantly impacting overall processing speed, as the correction is integrated into the conveyance and reading workflow rather than being a separate post-processing step.
Data Source
AI summary
An image reading device includes: a supplying tray on which a document is placed; a document conveyer that successively conveys the document placed on the supplying tray toward a reading position; a plurality of detection sensors that are disposed in a plurality of positions in a width direction intersecting a conveyance direction of the document, and detect a front edge of the document in the conveyance direction when the document is placed on the supplying tray; and a document reading portion that reads an image on the document passing the reading position, and generates an image signal.