Barcode Scanner Direction Tracking via Video Transition Counting
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Solution Overview
Problem
Bar code scanners face difficulties in determining the direction of moving items, leading to issues like double scanning and reduced throughput, due to ambiguous readings and the need for additional hardware or continuous bar code visibility.
Innovation Solution
The method involves sensing video transitions in a pair of scan planes, counting these transitions, and comparing them to a threshold to determine if the item intersects the planes, with subsequent samples used to evaluate the direction of movement, thereby eliminating duplicate scans without requiring long time-outs or additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively long delay is required between good reads of bar code label on identical items to avoid multiple read problem, then duplicate scans are eliminated, but scanning throughput is reduced
Solution Approach 1:
The patent replaces the mechanical time-delay system with an optical sensing system. Instead of using temporal separation (time delays) to prevent duplicate scans, the invention uses spatial separation through multiple scan planes to detect item direction and position, allowing real-time duplicate elimination without throughput penalty
Solution Approach 2:
The patent introduces video transition information as an intermediary to determine item direction. By sensing light reflections from packaging graphics and analyzing transition patterns across multiple scan planes, the system obtains directional information without requiring time delays or additional hardware gates
2Reliability
If item gates utilizing LED and photocell pair are used to detect item entering and exiting scan zone, then duplicate scan problem is addressed, but additional hardware cost is increased
Solution Approach 1:
The patent makes the existing laser bar code scanner multi-functional by enabling it to perform both bar code reading and item direction detection using the same laser beam and photodetector. The scanner simultaneously collects video transition information from packaging graphics while reading bar codes, eliminating the need for separate LED-photocell gate hardware
Solution Approach 2:
The patent merges the functions of bar code scanning and item detection into a single system. By processing video transition data from the same optical path used for bar code reading, the invention combines two previously separate functions (bar code detection and item presence/direction detection) into one integrated scanner
3Measurement precision
If motor positional information is used to determine bar code location and item exit from scan zone, then scan zone monitoring is achieved, but continuous bar code visibility is required which does not happen on many scans
Solution Approach 1:
The patent changes the detection parameter from bar code pattern recognition to video transition counting. By sensing light reflections from packaging graphics and counting transitions between light and dark regions, the system obtains item presence and direction information without requiring the bar code to be continuously visible or readable
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 effectively determines the direction of moving items, reducing double scanning and improving scanning throughput by accurately distinguishing between new and previously scanned items, even when they have the same bar code label, without the need for additional hardware or continuous bar code visibility.
Implementation Method 1
The reflected light returns along the incident path and is focused onto a photodetector. The photodetector converts this collected light energy into an electrical signal.
Implementation Method 2
The light beam is generated by a laser, usually a laser diode, and associated optics.
Implementation Method 3
Bar code scanners typically operate by using a motor and pattern mirrors to scan a light beam across a label surface
Data Source
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AI summary
Methods, computer readable medium, and apparatus for tracking the direction of a moving item by laser bar code scanners are disclosed. In particular, the method includes the following steps at a first sample in time. Those steps include sensing video transitions reflected off packaging graphics of the moving item by a pair of scan planes, counting the number of video transitions sensed by each scan plane of the pair of scan planes, and determining if the moving item intersects each of the scan planes by comparing the counted number of video transitions for each scan plane of the pair with a predetermined threshold at the first sample. At a second sample in time, the above steps are repeated and the method includes the additional step of evaluating the direction of movement of the moving item from changes observed from the first sample and the second sample.