Virtual Scan Line Remapping for Barcode Reading Accuracy
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Solution Overview
Problem
Handheld imaging readers face challenges in accurately reading bar code symbols across extended ranges due to partial scanning, leading to 'short read' decoding errors, especially with symbologies having weak start/stop characters, which requires complex controller configurations and reduces productivity.
Innovation Solution
A solid-state imager with a programmed microprocessor that maps and remaps virtual scan lines to ensure complete coverage of the symbol, eliminating the need for decode restrictions by determining the orientation and extending the scan line to include all bars and spaces, thereby enhancing reading performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the virtual scan line is mapped across the symbol field, then the symbol can be read, but the scan line may be tilted or short causing short read decoding errors
Solution Approach 1:
The system analyzes the captured symbol image to detect the actual orientation and position of the symbol, then uses this feedback information to dynamically remap the virtual scan line. This closed-loop approach ensures the scan line aligns precisely with the symbol boundaries, eliminating tilted or short scan lines that cause decoding errors.
Solution Approach 2:
Before decoding the symbol, the system performs preliminary analysis of the captured image to determine the symbol's orientation and extent. Based on this preliminary assessment, the virtual scan line is pre-adjusted and remapped to ensure it will traverse the complete symbol, preventing short read errors before they occur.
2Reliability
If decode restrictions are applied to prevent short reads, then decoding reliability improves, but device complexity increases
Solution Approach 1:
The system performs self-correction by automatically detecting symbol orientation and remapping the scan line without requiring external intervention or complex decode restriction logic. The controller serves itself by adapting the scan line configuration based on real-time image analysis, eliminating the need for cumbersome redundancy checks and character validation restrictions.
3Measurement precision
If the operator manually adjusts the reader position multiple times, then the symbol can be successfully read, but productivity decreases
Solution Approach 1:
The system replaces the manual mechanical adjustment process with an automated optical-digital solution. Instead of requiring the operator to physically reposition the reader, the system uses image capture, digital analysis of symbol orientation, and software-based remapping of the virtual scan line to achieve accurate reading, dramatically improving transaction processing speed.
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 reduces short read decoding errors and enhances the responsiveness and reading performance of imaging readers by ensuring complete symbol traversal without requiring additional decode restrictions, improving the accuracy and efficiency of data capture.
Implementation Method 1
The imaging reader includes an imaging module having a solid-state imager with a sensor array of photocells or light sensors, which correspond to image elements or pixels in a two-dimensional field of view of the imager, and an imaging lens assembly for capturing return light scattered and/or reflected from the symbol being imaged, and for projecting the return light onto the sensor array to initiate capture of an image of the symbol as pixel data
Data Source
AI summary
An arrangement for, and a method of, enhancing performance of an imaging reader for imaging symbols to be read, include a solid-state imager supported by the reader and having an array of image sensors for capturing return light from a symbol as pixel data over a field of view, and a controller operatively connected to the imager, for mapping a virtual scan line in the field of view, for determining whether the virtual scan line extends entirely over the symbol, for remapping the virtual scan line as a remapped virtual scan line that extends entirely over the symbol upon determining that the virtual scan line extends partially over the symbol, and for decoding the pixel data that lies on the remapped virtual scan line.