Non-imaging Light Collector Array for Extended Range Barcode Scanning
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Solution Overview
Problem
Laser scanners using non-imaging light collectors are limited to short ranges due to the difficulty in collecting sufficient reflected light at longer distances and are affected by ambient noise, requiring larger photodetectors and wider scan angles to read bar codes effectively.
Innovation Solution
An electro-optical scanner with a two-dimensional array of non-imaging light collectors, where the total area of the entrance apertures is greater than 50% of the target-facing surface, and a corresponding array of photodetectors positioned at the exit apertures, configured to match the scan angle and reject ambient light, enhancing light collection and concentration for extended range scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If non-imaging light collectors are used to collect reflected light, then light concentration onto photodetector is improved, but working range is limited to short distances
Solution Approach 1:
The patent divides the light collection system into an array of multiple non-imaging light collectors instead of using a single collector. Each light collector in the array concentrates light onto a corresponding photodetector, and the combined effect of multiple collectors enables effective operation at extended ranges while maintaining light concentration capability.
Solution Approach 2:
The patent transitions from a single-point light collection approach to a two-dimensional array of light collectors. This dimensional expansion allows the system to capture light from a broader angular range and increase the total light-gathering area, thereby extending the working range while maintaining concentration efficiency.
2Illumination intensity
If larger photodetectors are used to increase light collection area, then light collection capability is improved, but capacitance increases and noise increases
Solution Approach 1:
The patent segments the photodetector array into multiple smaller photodetectors, each paired with a corresponding light collector. This segmentation allows each photodetector to remain small (minimizing capacitance and noise) while the array of collectors provides sufficient total light collection area through distributed light concentration.
Solution Approach 2:
The non-imaging light collectors act as intermediaries between the reflected light and the photodetectors. These light collectors concentrate and direct light onto the photodetector active regions, enabling small photodetectors to effectively collect sufficient light without requiring large photodetector areas that would increase noise.
3Ease of operation
If wider scan angles are used to read bar codes at short range, then reading capability is improved, but ambient light interference increases
Solution Approach 1:
The patent assigns specific collection angles to individual light collectors in the array, with each collector optimized for a particular angular range. This local optimization allows the system to maintain narrow individual collection angles (reducing ambient light interference) while the collective array provides the necessary scan angle coverage for effective bar code 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 enables extended working range laser scanning with smaller photodetectors, improving signal-to-noise ratio and reducing ambient light interference, allowing for effective decoding of bar codes at longer distances with a compact scanner design.
Implementation Method 1
The elements or features of a bar code, e.g., black bars and white spaces of a UPC bar code, absorb and diffusely reflect the laser beam light
Implementation Method 2
non-imaging light collectors have been utilized in laser scanners to facilitate reading of bar codes... collect and concentrate light on a photodetector
Implementation Method 3
each photodetector in the array of photodetectors positioned at the exit aperture of a respective light collector of the array of light collectors to receive concentrated light from its respective light collector and generating an output electrical signal corresponding to an intensity of the concentrated light received by the photodetector
Implementation Method 4
The laser scanner generates a beam of light, typically a laser beam, which is repeatedly scanned across a target bar code
Data Source
AI summary
An extended working range electro-optical scanner (10) for reading a target bar code (100). The scanner (10) includes a scan engine (20) including a beam assembly (30) for repetitively directing a beam of light (SB2) at a scan angle (β) across the target bar code (100); an array of non-imaging light collectors (40) for collecting and concentrating reflected light from the target bar code (100), each light collector (40a-h) of the array of light collectors (40) having an entrance aperture (44) and an exit aperture (46) and wherein a total area of the entrance apertures (44) of the array of light collectors (40) is greater than 50 percent of a total area of a target-facing surface of the scan engine; and a corresponding array of photodetectors (60), each photodetector (60a-h) in the array of photodetectors (60) positioned at an exit aperture (46) of a respective light collector (40a-h) of the array of light collectors (40) to receive concentrated light from its respective light collector (40a-h) and generating an output electrical signal corresponding to an intensity of the concentrated light received by the photodetector (40a-h).