Tapered Diffuser for Handheld Symbology Reader Illumination
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Solution Overview
Problem
Current image acquisition devices for reading industrial identification codes face challenges in providing effective illumination, particularly on irregular surfaces and specular surfaces, where bright field illumination can scatter and obscure images, and non-directional diffuse illumination is difficult and costly to achieve.
Innovation Solution
A handheld reader with a tapered translucent diffuser converts bright field illumination into non-directional diffuse illumination, and optionally combines it with low-angle dark field illumination using passive or active light pipes, allowing for selective or simultaneous illumination modes to enhance image contrast and clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If bright field illumination is used to illuminate barcodes on flat surfaces, then illumination intensity is improved, but image contrast deteriorates on irregular and specular surfaces due to scattering
Solution Approach 1:
The illumination system is segmented into multiple independent light sources positioned at different angles, allowing selective activation of bright field or dark field illumination modes depending on surface characteristics, thereby maintaining both high illumination intensity and reliable image contrast across different surface types
Solution Approach 2:
The system dynamically switches between different illumination modes (bright field, dark field, and combined modes) based on detected surface properties, enabling adaptive optimization of both illumination intensity and image contrast for varying barcode substrates
2Reliability
If dark field illumination is used to illuminate barcodes on irregular surfaces, then image contrast is improved, but illumination intensity decreases due to low incidence angle requirements
Solution Approach 1:
The system merges dark field illumination with supplemental bright field illumination sources, combining the high contrast advantage of dark field with the high intensity advantage of bright field to achieve both improved image contrast and sufficient illumination intensity simultaneously
3Reliability
If non-directional totally diffuse illumination is used to illuminate barcodes on specular surfaces, then image contrast is improved, but device complexity and cost increase due to requiring surrounding light tents
Solution Approach 1:
The patent transitions from two-dimensional surface illumination to three-dimensional volumetric diffusion by introducing a translucent diffuser medium that surrounds the optical axis, creating uniform non-directional illumination from multiple directions without requiring complex external light tents, thereby achieving high image contrast with simplified device structure
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 high contrast images of symbols and barcodes on various surfaces by ensuring uniform diffuse illumination and low-angle dark field illumination, improving image acquisition on both flat and irregular surfaces without the need for costly lighting setups.
Implementation Method 1
The tapered diffuser converts bright field illumination into totally diffused non-directional illumination
Data Source
AI summary
A hand held industrial identification symbol reader projects diffuse illumination onto a region of interest to produce high contrast images of symbols. The diffuse illumination is particularly well suited for producing images of symbols that are marked directly on objects. The diffuse illumination is created through the use of an optically translucent diffuser having a generally tapered shape that distributes diffuse illumination throughout the field of view of the reader. The diffuse illumination can be supplemented with dark field illumination using selectively actuated illumination sources.