Direct Part Marking Code Reading with Surface-Adaptive Illumination
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Solution Overview
Problem
Conventional DPM readers face challenges in discerning DPM symbols under varying lighting conditions due to specular reflections and loss of contrast, especially when symbols are not in contrasting colors with the background, and illumination can exacerbate these issues.
Innovation Solution
An optical symbol reading system with an image sensor, color-sensing system, and illumination system that autonomously adjusts illumination parameters based on surface characteristics, including color, distance, and orientation, using a surface-profiling system to enhance symbol detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If illumination is added to improve visibility of DPM symbols, then symbol detection capability is improved, but specular reflections increase which drown out the symbol or saturate the image sensor
Solution Approach 1:
The system performs preliminary assessment of surface characteristics (color, distance, orientation, reflectivity) using color-sensing and surface-profiling systems before activating the illumination system. This allows the control circuitry to pre-determine optimal illumination parameters and capture settings, adjusting them in advance to prevent specular reflections from saturating the sensor while ensuring adequate symbol visibility.
Solution Approach 2:
The illumination system includes multiple sets of photo emitters that can be selectively activated based on assessed surface characteristics. The control circuitry dynamically adjusts illumination parameters (intensity, color temperature, activation of specific emitter sets) according to the measured surface properties, changing parameters in real-time to optimize symbol detection while minimizing harmful specular reflections.
2Illumination intensity
If illumination intensity is increased to improve symbol visibility, then symbol discernment is improved, but contrast between symbol features and background is reduced
Solution Approach 1:
The system applies different illumination qualities to different local conditions by selecting specific sets of photo emitters based on assessed surface characteristics. For surfaces with high reflectivity or specific colors, the system activates emitters with complementary color characteristics or lower intensity, while for darker or less reflective surfaces, it activates emitters providing higher intensity or different spectral content, creating locally optimized illumination quality for each surface type.
Solution Approach 2:
The illumination system utilizes multiple sets of photo emitters that can produce different color characteristics. The control circuitry selects and activates specific emitter sets based on the assessed color of the target surface, using color theory to choose illumination colors that maximize contrast between the DPM symbol and background. For example, illuminating a red surface with blue-rich light enhances contrast for dark symbols on red backgrounds.
3Ease of operation
If reading distance is increased to improve operator safety or ergonomics, then operator protection is improved, but measurement precision of surface characteristics and symbol reading deteriorates
Solution Approach 1:
The system replaces the need for close physical proximity with optical and electronic measurement systems. Color-sensing systems, surface-profiling systems using time-of-flight or phase-shift measurement, and multiple cameras capture surface characteristics and symbol information from greater distances. Electronic signal processing and image processing algorithms then extract precise measurements and read symbols accurately, substituting mechanical proximity requirements with remote sensing capabilities.
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 system effectively reads DPM symbols by optimizing illumination and image capture settings, improving symbol discernment and reliability under diverse conditions.
Implementation Method 1
an illumination system including a plurality of sets of photo emitters that are operative to produce various types of illumination based on illumination parameters
Implementation Method 2
a portion of the emitted light is reflected from any object of interest present in the target area and received by the image sensor and the color-sensing system
Implementation Method 3
a surface-profiling system that is distinct from the image sensor, and is arranged to measure distance to multiple points of at least one surface in the target area
Data Source
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AI summary
An optical symbol reading system comprises an image sensor operative to capture an image of a target area, a color-sensing system sensitive to certain colors in the visible spectrum, an illumination system operative to produce various types of illumination based on illumination parameters, and a surface-profiling system arranged to measure distance to multiple points of at least one surface in the target area. The illumination system, the image sensor, and the color-sensing system are arranged such that emitted light from the illumination system, in accordance with a selected type of illumination, is directed towards the target area while a portion of the emitted light is reflected from any object of interest present in the target area and received by the image sensor and the color-sensing system. The type of illumination is selected based on output from the color-sensing system and the surface-profiling system.