Dual Illumination Optical Reader for Near-Far Field Readability
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Solution Overview
Problem
Optical reading devices face challenges in efficiently reading data from both near and far field positions due to variations in illuminance and field of view, which affect the accuracy and tolerance of hand motion during scanning.
Innovation Solution
The optical reader employs a dual illumination system with a first illumination source providing a brighter field at a distance and a second source with a more compressed field, combined with an image sensor array and processor for decoding information, ensuring adequate illuminance and field coverage for both near and far targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single illumination source is used, then the device complexity is reduced, but the illuminance uniformity across different distances deteriorates
Solution Approach 1:
The illumination system is segmented into multiple illumination sources, each optimized for specific distance ranges. This allows the system to provide appropriate illuminance for both near and far field targets without requiring a single complex adjustable source, thereby resolving the contradiction between device simplicity and illumination uniformity.
Solution Approach 2:
Different illumination sources are positioned and configured to provide localized illumination optimization for specific spatial zones (near field vs. far field). Each source has tailored characteristics (intensity, beam angle, position) suited to its designated operating range, achieving uniform illuminance across varying distances while maintaining reasonable system complexity.
2Adaptability or versatility
If the field of view is expanded to cover both near and far targets, then the adaptability is improved, but the measurement precision deteriorates
Solution Approach 1:
The optical system dynamically adjusts its effective field of view and focus characteristics based on the target distance. By switching between different illumination sources and corresponding imaging configurations, the system maintains optimal precision for the current reading distance while preserving adaptability across the full range of operating distances.
Solution Approach 2:
The system changes key optical parameters (illumination intensity, field of view angle, focal length) depending on the operating distance. This allows the measurement precision to be optimized for each distance range while maintaining overall system adaptability, resolving the contradiction between fixed precision and variable range.
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
This configuration enhances readability at varying distances, improves hand motion tolerance, and allows for efficient decoding of information-bearing indicia, regardless of the target's proximity to the reader.
Implementation Method 1
an image sensor array for converting light from a target into output signals representative thereof
Data Source
AI summary
An optical reader comprises: a first illumination source for projecting a first illumination field on a target; a second illumination source for projecting a second illumination field on a target; an image sensor array for converting light from a target into output signals representative thereof; and, a processor for decoding information from information bearing indicia within the target derived from the output signals; and, wherein the illuminance of the first illumination field on the target at a distance D from the first illumination source is greater than the illuminance of the second illumination field on the target at the distance D from the second illumination source.