Elongated Laser Beam Bar Code Reader for Damaged Symbols
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Solution Overview
Problem
Current bar code symbol reading systems face challenges in achieving enhanced signal-to-noise ratio (SNR) performance when reading poor quality or damaged bar codes, particularly with elongated laser beams, as the optimization of beam elongation ratio (ER) for improved SNR has not been adequately addressed.
Innovation Solution
The implementation of a bar code symbol reading system utilizing an extremely elongated laser beam with an elongation ratio greater than 4.5, achieved through the use of a curved mirror or cylindrical lens, to enhance SNR performance by averaging out defects in bar code symbols during scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elongated laser beam is used to scan bar code symbols, then the signal to noise ratio (SNR) performance is improved by averaging out spatial noise, but the beam elongation ratio (ER) optimization is insufficient for reading poor quality and damaged bar codes
Solution Approach 1:
The patent applies parameter changes by systematically varying the beam elongation ratio (ER) from conventional values (1-4.5) to extreme values (greater than 4.5). This parameter optimization enables the laser beam to achieve enhanced SNR performance while maintaining the capability to read poor quality and damaged bar code symbols across the working range, directly resolving the insufficiency in ER optimization
2Reliability
If the laser beam is made extremely elongated with ER > 4.5, then the reading capability of poor quality and damaged bar codes is enhanced, but the device complexity increases due to additional optical elements
Solution Approach 1:
The patent applies local quality by modifying only the specific optical components needed to achieve extreme beam elongation (cylindrical lens or curved mirror) while leaving the rest of the laser scanning system unchanged. This localized modification approach enhances reading capability for damaged bar codes without requiring complete system redesign, thereby limiting the increase in overall device complexity
3Device complexity
If conventional elongated laser beams are used, then the system maintains simple optics, but the SNR performance is insufficient for damaged bar code reading
Solution Approach 1:
The patent resolves this contradiction by changing the beam elongation ratio parameter to extreme values (ER > 4.5), which provides the necessary SNR enhancement for damaged bar code reading. The parameter change is achieved through simple optical modifications (cylindrical lens or curved mirror) that maintain relative system simplicity while dramatically improving SNR performance
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 improves the SNR performance of bar code symbol reading systems, enabling effective reading of poor quality and damaged bar codes across the working range, including at the point of highest resolution, by maintaining extreme elongation at the beam waist.
Implementation Method 1
The use of a curved mirror or cylindrical lens to elongate the laser beam in the cross-scan direction to achieve an elongation ratio greater than 4.5
Implementation Method 2
enhance SNR performance by averaging out defects in bar code symbols during scanning
Data Source
AI summary
The system includes a housing having a light transmission window and produces an extremely-elongated laser beam having an elongation ratio (ER) that is defined as greater than 4.5 for any point within the working range of the laser scanning bar code symbol reading system. A laser scanning mechanism is provided for scanning the extremely-elongated laser beam out the light transmission window and across a scanning field defined external to the housing, in which a bar code symbol is present for scanning by the extremely-elongated laser scanning beam.