Mail Double-Feed Detection Using Multi-Angle Line-Scan Imaging
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Solution Overview
Problem
Automated sorting machines often experience double feeds due to misidentification of special mail types, leading to increased sorting machine jams and incorrect delivery of mail items, with existing double-feed detection methods failing to accurately distinguish between single and double feeds in such cases.
Innovation Solution
The implementation of an electronic line-scan camera with its optical axis transverse to the transport direction, allowing simultaneous viewing of the bottom edges and sides of mail pieces, either through additional cameras or angled optics, to compare scanned images with predetermined characteristics for accurate double-feed detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a line-scan camera is used to detect double feeds by looking up at the base of mail items, then double-feed detection is achieved, but false-doubles occur with special envelope types causing incorrect identification
Solution Approach 1:
The patent transitions from a single-dimensional bottom-view detection approach to a multi-dimensional detection system by adding side-view capability. The camera system now captures images from both the bottom base and the side of mail items, creating a two-dimensional view that enables accurate distinction between single and double feeds, especially for special envelope types that cause false-doubles with bottom-view alone.
2Reliability
If additional cameras or angled optics are added to view the side of mail pieces, then false-double rate is reduced, but device complexity increases
Solution Approach 1:
The patent makes the camera system multi-functional by enabling a single camera to capture both bottom-base views and side views of mail items. This is achieved through strategic positioning and optical configuration where the same camera apparatus serves dual detection purposes, eliminating the need for separate dedicated cameras for each view angle and thus reducing overall system complexity.
3Reliability
If simultaneous side and bottom edge viewing is implemented, then double-feed detection reliability is improved, but measurement and detection difficulty increases
Solution Approach 1:
The patent segments the detection task into distinct functional components: capturing bottom-base images, capturing side images, and then processing these separate image sets independently before integrating the results. This segmentation allows the system to handle the complexity of multi-angle detection by breaking it down into manageable stages, where each stage processes specific visual information before the results are combined for final double-feed determination.
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
This approach significantly reduces false-double feed detections, ensuring accurate sorting by providing a more comprehensive view of mail pieces, thereby minimizing errors and improving the reliability of double-feed detection systems.
Implementation Method 1
an electronic line-scan camera with its optical longitudinal axis transverse to the transport direction of the mail pieces whereby a scan of the bottom edges of the mail pieces through an aperture in the base place is obtained
Implementation Method 2
means are provided for simultaneously viewing the side of a piece of mail adjacent the bottom edge simultaneously with the bottom edges
Data Source
AI summary
This invention relates to a method of detecting double-feed of email items (10,12) that allows difficult mail types to be processed correctly, wherein simultaneous views are taking of both the sides and bottom of mail items and these views are processed to determine whether or not double feed has occurred. This can be achieved using either two cameras or a single camera (16,2) with additional optics.