Optical Barcode Sensing With Tolerance and Least-Deviation Decoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical sensors struggle to reliably detect 4-width barcodes due to contamination, damage, or variations in printing widths, leading to misreads.
Innovation Solution
An optical sensor with an evaluation unit that uses a decoding table to compare edge-to-edge distances with predefined tolerance limits and applies a method of smallest deviations to assign code elements, ensuring accurate barcode recognition even in disturbed signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional barcode detection methods are used, then the detection process is simple and fast, but the reliability of barcode detection deteriorates due to contamination, damage, or printing variations
Solution Approach 1:
The patent implements a dynamic evaluation process that adapts between two modes: a fast first evaluation using simple tolerance limits for clear barcodes, and a more complex second evaluation using deviation methods for disturbed barcodes. This dynamic switching maintains reliability while optimizing processing efficiency based on actual barcode quality.
Solution Approach 2:
The patent applies partial action by implementing a two-stage evaluation process where the more complex deviation method is only applied when necessary (when the first evaluation fails), rather than always using the most complex method. This ensures high reliability while avoiding unnecessary computational overhead for clear barcodes.
2Reliability
If tolerance limits are used for robust detection, then detection robustness improves, but measurement precision deteriorates due to ambiguous assignments
Solution Approach 1:
The patent performs a preliminary evaluation using simple tolerance limits before applying the more precise deviation method. This preliminary action quickly identifies clear barcodes that don't need complex analysis, while reserving precise deviation-based assignment for cases where robustness is needed, thus balancing both precision and robustness.
Solution Approach 2:
The patent introduces a hierarchical evaluation structure where the first evaluation (tolerance limits) acts as an intermediary filter. Clear cases are resolved by this intermediary layer, while only ambiguous or disturbed cases proceed to the second evaluation (deviation method), thus maintaining precision where possible and providing robustness when needed.
3Measurement precision
If a strict matching procedure is used, then measurement precision is maintained, but detection reliability deteriorates when barcodes are contaminated or damaged
Solution Approach 1:
The patent dynamically switches between strict matching (first evaluation with tolerance limits) and flexible matching (second evaluation with deviation methods) based on barcode quality. This dynamic approach maintains precision for clear barcodes while ensuring reliability for disturbed barcodes by adapting the matching strictness to the actual signal quality.
Solution Approach 2:
The patent converts the harmful effect of contamination and damage into a manageable condition by implementing a two-stage evaluation. When distortion is detected in the first stage, the system transitions to the second stage which is specifically designed to handle disturbed signals, thus turning the previously harmful situation into a solvable problem with appropriate methodology.
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
Enhances error reliability and insensitivity to barcode contamination or damage by accurately assigning code elements using edge-to-edge distance comparisons within tolerance limits and least-deviation methods.
Implementation Method 1
An optical sensor (1) for detecting 4-width barcodes with a light-emitting transmitter unit (4, 8), a light-receiving receiver unit (5, 9)
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to an optical sensor (1) for detecting 4-width barcodes, comprising a light-emitting transmitter unit (3), a light-receiving receiver unit (3), and an evaluation unit (6) in which the received signals from the receiver unit are evaluated. Each barcode (7) has a sequence of code elements with elements of predetermined widths, the widths of the elements of the code elements of each barcode (7) being stored in the evaluation unit (6) in the form of a decoding table. In the evaluation unit (6), a digital signal is generated from the received signals of the receiver unit, with edge positions of code elements being detected by changes in the signal states of the digital signal.A sequence of edge-to-edge distances (ei) formed by the spacing of adjacent edge positions is assigned to a code element if this sequence of edge-to-edge distances (ei) corresponds to the widths of the elements of that code element within predefined tolerance limits. A barcode (7) is considered recognized if a sequence of edge-to-edge distances (ei) can be assigned to each code element of the barcode (7). A barcode (7) is also recognized if, using a method of least deviation of the edge-to-edge distances (ei) with respect to the widths of the elements of the code elements of a barcode (7), at least one code element can be assigned to the sequence of edge-to-edge distances (ei), and if the remaining code elements can each be assigned to a sequence of edge-to-edge distances (ei) by the fact that the respective edge-to-edge distances (ei) correspond to the widths of the elements of the respective code element within predefined tolerance limits.