Document Size Detection in Image Scanners
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Solution Overview
Problem
Existing image reading apparatuses face challenges in accurately detecting document sizes, particularly with curled or folded documents, leading to false size detection and impaired user convenience due to incomplete or excessive image data generation.
Innovation Solution
The apparatus employs a dual identification system, where a first identification unit determines the document size before conveyance and a second unit confirms it during conveyance, allowing for different control actions based on size discrepancies to ensure accurate reading processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If error processing is performed every time false size detection occurs, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system changes the error handling parameter based on the type of size discrepancy detected. When the detected size is larger than actual (reading area exceeds document), no error processing is performed. When the detected size is smaller than actual (image data incomplete), error processing is executed. This conditional parameter change resolves the contradiction by adapting the strictness of error handling to the specific detection scenario.
2Device complexity
If document size is detected using presence/absence sensor, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The detection process is segmented into two independent stages: (1) presence/absence detection using simple sensors to determine if a document exists and its apparent size, and (2) verification through reading control that compares detected size with actual reading area. This segmentation allows using simple sensors while achieving precise measurement through the combined two-stage approach.
Solution Approach 2:
The reading control unit provides feedback by comparing the document size detected by the presence/absence sensor with the actual reading area. This feedback mechanism allows the system to identify false detections (when detected size differs from actual size) and handle them appropriately, thereby improving measurement precision without increasing sensor complexity.
3Reliability
If reading area is set larger than actual document size, then reliability is improved, but loss of substance increases
Solution Approach 1:
The system applies partial action by adjusting the reading area precisely to match the detected document size rather than always using a fixed large reading area. The reading control unit modifies the reading parameters based on the detected document dimensions, performing exactly the necessary reading action without excessive coverage, thus eliminating unnecessary data generation while ensuring complete capture of the actual document.
Data Source
AI summary
An image reading apparatus includes a reading unit that reads an image on a document, a document conveyance unit that conveys the document to the reading unit, a first identification unit that identifies a size of the document before the document begins to be conveyed, a reading control unit that controls the reading unit to read the document, based on the size identified by the first identification unit, and a second identification unit that identifies a size of the document after the document begins to be conveyed, wherein the reading control unit performs control to, in a case where the size identified by the first identification unit is smaller than the size identified by the second identification unit, cancel reading processing, and in a case where the size identified by the first identification unit is greater than the size identified by the second identification unit, continue the reading processing.