Sheet-fed Scanner Background Light Source for Document Boundary Detection
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Solution Overview
Problem
Sheet-fed scanners face challenges in accurately distinguishing document images from background images due to the strip-shaped background, which lacks patterns and can have colors similar to the documents, leading to insufficient image precision and errors in processing.
Innovation Solution
A sheet-fed scanner with a background sheet that displays an intermittent variation background image using a background light source, allowing the scan module to capture stripe patterns with light and shade contrast, enabling precise identification of document boundaries and sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a strip-shaped background sheet is used in sheet-fed scanner, then the scanner has small volume and fast scanning speed, but the background sheet cannot have vein or pattern designed thereon, making it difficult to identify document boundaries when background color is similar to document color
Solution Approach 1:
The background light source emits light in periodic on-off cycles, creating intermittent light and dark stripes on the background sheet. This periodic illumination generates high-contrast vertical stripe patterns that enable accurate document boundary detection while maintaining the compact sheet-fed scanner structure.
Solution Approach 2:
The background sheet displays dynamic color changes between light and dark states through periodic illumination. The light stripes appear bright while dark stripes appear dim, creating strong visual contrast that facilitates precise document boundary identification even when document colors are similar to the background sheet color.
2Measurement precision
If a complete sheet of background sheet with vein or pattern is used, then background image can be easily identified, but the scanner becomes large in size and cannot automatically scan large volume of documents
Solution Approach 1:
Instead of using a static patterned background sheet that would require larger scanner volume, the patent employs periodic illumination to dynamically generate stripe patterns on a simple strip-shaped background. This enables high-precision background identification while maintaining compact size and automatic scanning capability for large volumes of documents.
Solution Approach 2:
The patent creates a virtual stripe pattern copy through light projection rather than using a physical patterned background sheet. The intermittent light signal from the background light source generates a copy of the stripe pattern on the background sheet, achieving the same identification function with reduced hardware complexity and smaller scanner volume.
3Reliability
If the background sheet color is too close to the scanned document color, then the document image and background image cannot be distinguished, but changing the background sheet color may not be sufficient when the document color varies
Solution Approach 1:
The periodic on-off illumination creates time-varying light and dark stripes that provide consistent high-contrast boundaries regardless of document color. This temporal modulation ensures reliable document-background distinction for documents of any color by creating artificial edge markers that are independent of the document's inherent color properties.
Solution Approach 2:
The background sheet undergoes dynamic color changes between light and dark states through periodic illumination. This creates strong contrast edges that are visible regardless of the document color, enabling reliable document boundary detection for documents of any color without requiring manual background sheet color adjustment.
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
The solution enables accurate identification of document images and backgrounds, improving image processing precision by generating scan data with stripe patterns, thus correcting size errors and skewness.
Implementation Method 1
The background light source faces towards the second surface to provide an intermittent light signal to the background sheet
Implementation Method 2
the scan module is disposed on another side of the scan channel, and captures a document image of the document and the intermittent variation background image to generate scan data
Data Source
AI summary
A sheet-fed scanner comprising a scan channel, a feeding unit, a transmitting unit, a background sheet, a background light source and a scan module is provided. The feeding unit is disposed at an inlet of the scan channel for feeding a document. The transmitting unit transmits the document to pass through the scan channel. The background sheet is disposed on a side of the scan channel, and has a first surface and a second surface. The first surface faces towards the scan channel. The background light source faces towards the second surface to provide an intermittent light signal to the background sheet, so that the background sheet correspondingly displays an intermittent variation background image on the first surface. The scan module is disposed on another side of the scan channel, and captures a document image of a document and the intermittent variation background image to generate scan data accordingly.