Image Scanner Document Alignment Detection
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Solution Overview
Problem
Image scanners face challenges in accurately detecting documents that are improperly aligned on the document table, leading to erroneous determination of document presence or absence due to misalignment, causing incorrect stopping of the scanning process.
Innovation Solution
The image scanner employs a controller to detect document leading edges and side edges, define middle and side areas, and apply specific ending processing based on document alignment, determining whether the document has a rectangular shape to accurately end the reading operation regardless of alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the image scanner uses a fixed threshold based on white document background color strength to detect document presence, then the detection speed is fast, but the reliability deteriorates when documents are misaligned
Solution Approach 1:
The patent segments the document detection area into multiple regions (first detection area, second detection area, third detection area) along the sub-scanning direction. By dividing the detection task into multiple zones, the system can identify documents even when they are misaligned, as at least one region should contain document content. This segmentation approach maintains fast processing while improving reliability for misaligned documents.
Solution Approach 2:
The patent changes the detection parameters dynamically based on the detected document characteristics. When document color strength varies in different regions, the system adjusts the threshold determination method - using maximum color strength for skewed documents and average color strength for non-skewed documents. This parameter adaptation allows accurate detection across various document alignment conditions.
2Productivity
If the image scanner stops reading when color strength changes from white background, then the reading process is efficient, but the reliability deteriorates due to false stopping on misaligned documents
Solution Approach 1:
The patent performs preliminary detection of document leading edges and side edges before completing the reading operation. By detecting the document boundaries in advance using the line sensor, the system can determine the complete reading area and adjust the reading process accordingly. This preliminary action prevents false stopping and ensures complete document capture even when misalignment occurs.
Solution Approach 2:
The patent implements feedback by continuously monitoring color strength changes during the reading process and using this information to adjust reading termination. The system compares color strength at different positions and uses this feedback to determine when to stop reading, preventing premature termination on misaligned documents while maintaining efficiency on properly aligned ones.
3Device complexity
If the image scanner uses a simple single-point detection method, then the device complexity is low, but the adaptability deteriorates for different document alignment configurations
Solution Approach 1:
The patent segments the detection function into multiple independent detection points (first, second, and third detection points) positioned at different locations. This segmentation allows the system to handle various document alignment configurations without increasing overall complexity, as each detection point operates independently and the results are combined to determine document presence and boundaries.
Solution Approach 2:
The patent adds a spatial dimension to the detection method by positioning multiple detection points at different locations along the sub-scanning direction. Instead of using a single point, the system uses a distributed detection array that captures document characteristics from multiple perspectives, enabling adaptation to various alignment configurations while maintaining manageable complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables successful reading of documents even when placed with leading edges parallel or not parallel to the main scanning direction, ensuring accurate detection and processing of documents with different alignment configurations.
Implementation Method 1
a reader including a line image sensor extending along a main scanning direction, the reader configured to read an image using the line image sensor
Data Source
AI summary
A controller executes area defining processing for defining a middle area and two side areas, and ending processing. In a case where the document leading edge extends parallel to a main scanning direction, the controller executes the ending processing for non-skewed document. In a case where the document leading edge does not extend parallel to the main scanning direction, the controller executes the ending processing for skewed document. In which, the controller determines, in the middle area and the side areas, first, second, and third change positions, respectively, at each of which a type of a target read image data line changes from document data to document cover data, determines, based on the first change position and the second change position, whether a document has a rectangular shape, and ends the reading operation based on the third change position and the determination result as to the document shape.