Tapered Lens Pipe Illumination for Barcode Readers
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Solution Overview
Problem
Conventional barcode readers with long-range capabilities pose an eye safety risk due to peak irradiance in discrete light spots, which can cause retina damage, as the light beams have high irradiance peaks resulting from the configuration of the optical system.
Innovation Solution
A barcode reader design featuring a light source larger than the input aperture of a tapered lens pipe, combined with reflectors to increase efficiency and distribute irradiance evenly, producing a rectangular light beam with reduced peak irradiance by a factor of seven or more, ensuring eye safety while maintaining high efficiency for reading machine-readable indicia at long distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-power LED light sources are used for long-distance barcode reading, then reading capability at long range is improved, but peak irradiance in discrete light spots increases causing eye safety risks
Solution Approach 1:
The light beam is segmented into multiple discrete spots that are then redistributed across a broader area through the lens pipe, transforming concentrated high-irradiance spots into a distributed homogeneous pattern that maintains reading capability while reducing peak irradiance
Solution Approach 2:
The optical system transitions the light distribution from a one-dimensional concentrated spot pattern to a two-dimensional homogeneous rectangular pattern, spreading the light energy across both horizontal and vertical dimensions to reduce peak irradiance while maintaining overall illumination levels
2Device complexity
If conventional optical system configuration is used, then device complexity is reduced, but peak irradiance creates harmful effects on the retina
Solution Approach 1:
The lens pipe acts as an intermediary optical element between the LED light source and the target barcode, transforming the light distribution pattern and eliminating direct line-of-sight concentrated beams that cause retinal damage while maintaining reading functionality
3Productivity
If light beam irradiance is increased for long-range reading, then reading efficiency is improved, but eye safety is compromised due to high peak irradiance
Solution Approach 1:
The system changes the spatial distribution parameters of the light beam, transforming concentrated high-irradiance spots into a homogeneous distributed pattern, which reduces peak irradiance by a factor of seven or more while maintaining overall irradiance levels necessary for efficient long-range reading
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 a high-efficiency, eye-safe illumination system that reduces peak irradiance significantly, preventing eye injury while maintaining the overall irradiance level, allowing for precise and safe reading of barcodes at extended ranges.
Implementation Method 1
A lens pipe having a tapered shape extending from a first end to a second end, where the first end defines an input aperture
Implementation Method 2
A projection lens may be disposed in front of the second end of the lens pipe, and be configured to project the light from the illumination source that enters the input aperture of the lens pipe substantially along an optical axis defined by the projection lens
Data Source
AI summary
A system and method of imaging barcodes may include generating a first light beam from an illumination surface having first dimensions. The first light beam may be directed into an input aperture of an optical component to form a second light beam. The input aperture has second dimensions, where the first dimensions are at least as large as the second dimensions. The second light beam having irradiation spatially distributed across the second light beam may be projected to read a machine-readable indicia.