Barcode Reader Adaptive Threshold Evaluation
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Solution Overview
Problem
Conventional barcode readers struggle to recognize barcodes within a large depth of field due to varying light beam focus, leading to asymmetrical signal profiles and incorrect detection of minima with positive values, which prevents accurate decoding.
Innovation Solution
An adaptive threshold evaluation method is employed, where threshold values are dynamically adjusted based on the differentiated received signal profile, allowing for reliable detection of minima and maxima, even when the light beam diameter exceeds the barcode element width, by using initial and changed threshold values to filter out noise and ensure accurate barcode decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed threshold values are used for minimum and maximum detection, then noise filtering is improved, but the ability to detect barcodes across varying depths deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from fixed threshold values to dynamically adjusted threshold values that adapt to the received signal profile. The evaluation unit determines threshold values based on the actual signal characteristics, allowing the system to maintain reliable noise filtering while adapting to varying depth conditions. This dynamic adjustment enables the code reader to accurately detect minima and maxima across different depths without requiring manual threshold reconfiguration.
Solution Approach 2:
The patent implements parameter changes by modifying the threshold values based on the received signal profile characteristics. The evaluation unit analyzes the signal and adjusts threshold parameters accordingly, transforming the static thresholding approach into a adaptive parameter adjustment mechanism. This allows the system to maintain optimal noise filtering performance while accommodating variations in light beam focus across different depths.
2Measurement precision
If light beams are focused at a fixed reading distance, then measurement precision is improved, but the depth of field range deteriorates
Solution Approach 1:
The patent applies feedback by having the evaluation unit continuously analyze the received signal profile and adjust threshold values based on the actual signal characteristics. This feedback mechanism allows the system to compensate for focus variations across different depths, maintaining measurement precision without requiring the light beams to be perfectly focused at a single fixed distance. The adaptive thresholds provide real-time compensation for depth variations.
3Measurement precision
If the diameter of transmitted light beams is made smaller than code element width, then measurement precision is improved, but the depth of field deteriorates
Solution Approach 1:
The patent resolves this contradiction by implementing dynamic threshold adjustment that adapts to the actual light beam diameter and signal characteristics at different reading distances. The evaluation unit analyzes the received signal profile and adjusts threshold values accordingly, allowing the system to maintain precise transition detection even when the light beam diameter varies with depth. This dynamic adaptation eliminates the need for fixed geometric constraints on light beam size.
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 method enables barcode readers to function effectively across a broader depth of field without design optimizations, ensuring reliable barcode recognition by adaptively adjusting thresholds to account for varying signal amplitudes and noise, thereby expanding the reader's usable range.
Implementation Method 1
The transmitted light beams are reflected by a barcode located within the sample area and directed to the receiver as received light beams
Implementation Method 2
The received light beams, and consequently the received signals at the receiver's output, exhibit amplitude modulation corresponding to the barcode's contrast pattern
Data Source
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AI summary
The invention relates to a method for detecting barcodes (B) using a code reader (1) comprising a transmitter (5) emitting light beams (4), a deflection unit, and a receiver (7) onto which the transmitted light beams (4) reflected back from a barcode (B) strike as received light beams (6). The transmitted light beams (4) periodically scan a sampling area within each scan using the deflection unit. The code reader (1) has an evaluation unit in which received signals at the output of the receiver (7) are evaluated according to the following process steps for detecting barcodes (B): • Generation of the differentiated temporal received signal profile for each scan, • Determination of final pairs of minima and maxima for each scan from this received signal profile using adaptive threshold evaluation.• Decoding the barcode (B) using the determined final pairs of minima and maxima for the respective scan.