Polarized Illumination for Shiny Surface DPM Decoding
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Solution Overview
Problem
Imaging-based barcode scanners face difficulties in reading Direct Part Marking (DPM) indicia on shiny surfaces, as existing scanners are large and cumbersome due to the need for a diffusive surface to enhance contrast, which complicates aiming and reduces portability.
Innovation Solution
The use of polarized illumination and a second linear polarizer to prevent at least 80% of onetime scattered light from entering the imaging lens, allowing for effective imaging and decoding of DPM indicia on shiny surfaces while minimizing the size of the scanner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diffusive surface is added to enhance contrast for reading DPM indicia on shiny surfaces, then the contrast and readability of the indicia is improved, but the device size increases and portability is reduced
Solution Approach 1:
The patent changes the optical parameters of the illumination light by using polarized light instead of conventional omnidirectional light. This parameter change allows the system to achieve high contrast on shiny surfaces without requiring a diffusive surface, thereby maintaining a compact scanner design. The polarized illumination selectively enhances the reflected light from the indicia while suppressing specular reflections from the shiny surface.
2Measurement precision
If a diffusive surface is used to improve contrast, then the imaging quality of DPM indicia is enhanced, but the device complexity and ease of operation are worsened due to complicated aiming requirements
Solution Approach 1:
The patent employs polarized illumination as a parameter change that simplifies the imaging process. The polarized light naturally suppresses specular reflections from shiny surfaces, eliminating the need for complex diffusive surfaces and complicated aiming procedures. This makes the scanner easier to operate while maintaining high imaging quality.
3Device complexity
If conventional illumination is used without polarization, then the device structure is simpler, but the ability to read DPM indicia on shiny surfaces is insufficient
Solution Approach 1:
The patent introduces polarized illumination as a parameter change that significantly improves the decoding capability on shiny surfaces. The polarized light interacts differently with the shiny surface and the indicia, creating sufficient contrast for reliable reading. This relatively simple modification to the illumination parameter achieves robust performance without requiring complex system changes.
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 enables efficient decoding of DPM indicia on shiny surfaces with reduced scanner size, improving portability and ease of use by filtering out unwanted light, thus enhancing the scanner's functionality and usability.
Implementation Method 1
generating a polarized illumination light by passing light from an illumination light source through a first linear polarizer
Implementation Method 2
detecting light scattered from the DPM indicia through a second linear polarizer while preventing at least 80% of onetime scattered light caused by the target object from entering the imaging lens arrangement
Data Source
AI summary
A method of decoding a Direct Part Marking (DPM) indicia. The method includes: (1) generating a polarized illumination light; (2) illuminating the DPM indicia with the polarized illumination; (3) detecting light scattered from the DPM indicia through a linear polarizer with an imaging sensor while the DPM indicia is illuminated by the polarized illumination to capture an image of the DPM indicia though an imaging lens while preventing at least 80% of onetime scattered light caused by the target object from entering the imaging lens; and (4) processing the image of the DPM indicia to decode the DPM indicia.