Segmented Diffuser for Uniform DPM Illumination
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Solution Overview
Problem
Direct part marking (DPM) codes on reflective, non-planar surfaces like metal and glass are challenging to read due to lack of contrast, hot spots, glare, and specular reflections, which degrade the performance of traditional imaging readers, especially handheld devices, under variable lighting conditions.
Innovation Solution
A method and arrangement for uniform illumination using a diffuser with varying thickness and surface textures, combined with strategically placed illumination light sources and a light baffle, to minimize hot spots and glare while maintaining high light throughput, allowing for effective reading of DPM codes on reflective surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a bulk diffuser is used to evenly spread illumination light, then hot spots and glare are minimized, but light transmission efficiency decreases significantly
Solution Approach 1:
The bulk diffuser is segmented into multiple discrete diffusing elements arranged in an array. Each element is spaced apart from others, allowing light to pass through the gaps between elements. This segmentation maintains light transmission efficiency while still providing diffusion to reduce hot spots and glare, resolving the contradiction between uniformity and efficiency.
2Loss of energy
If illumination light sources are placed close to the diffuser to maximize light throughput, then light transmission efficiency increases, but hot spots on the diffuser become more intense
Solution Approach 1:
The diffusing elements are designed with specific local properties - they are translucent rather than transparent, and are arranged in a spaced array pattern. This local quality allows each element to diffuse light from nearby sources while the spacing between elements prevents concentration of light into hot spots, resolving the contradiction between throughput and hot spot intensity.
3Illumination intensity
If highly diffusive material is used to eliminate hot spots, then uniform illumination is achieved, but light transmission efficiency becomes extremely low
Solution Approach 1:
Rather than using a single piece of highly diffusive material, the solution segments the diffusion function into multiple discrete translucent elements spaced apart. This allows light to pass through the gaps between elements, maintaining high transmission efficiency while still achieving uniform illumination through the diffusion provided by each element.
4Ease of operation
If traditional imaging readers are used to read DPM codes on reflective surfaces, then reading capability is provided, but performance degrades due to hot spots, glare, and specular reflections
Solution Approach 1:
The array of spaced diffusing elements acts as an intermediary between the light sources and the DPM code on the reflective surface. This intermediary structure diffuses the illumination light to eliminate hot spots and glare before it reaches the code, while still allowing sufficient light transmission to illuminate the code uniformly for reliable reading by the imaging reader.
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 solution provides uniform background illumination, reducing hot spots and glare, and increasing light throughput, enabling reliable reading of DPM codes on complex surfaces without the need for extremely bright light sources, thus improving the decoding performance of DPM codes on reflective workpieces.
Implementation Method 1
A diffuser is operative for diffusing the illumination light en route to the indicia. The diffuser includes a plurality of diffusing elements adjacent the illuminator for diffusing the illumination light of greater intensity more than the illumination light of lesser intensity
Data Source
AI summary
Performance of an imaging reader for electro-optically reading direct part markings on workpieces is enhanced by uniformly illuminating the markings. An illuminator is operative for emitting illumination light of greater and lesser intensity toward the indicia. A diffuser is operative for diffusing the illumination light en route to the indicia. The diffuser includes a plurality of diffusing elements adjacent the illuminator for diffusing the illumination light of greater intensity more than the illumination light of lesser intensity.