Barcode Illumination Assembly Using Segmented Window for Distance Adaptation
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Solution Overview
Problem
Barcode readers face challenges in maintaining appropriate illumination levels across varying working distances, especially at the far reaches of their operable range, due to the directional nature of the illumination light, which can result in diminished performance.
Innovation Solution
The illumination assembly includes a lens with freeform polynomial surfaces that redirect and collimate the illumination light, combined with a window that splits the light into two portions with different divergence angles, ensuring adequate illumination across both near and far working distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a directional illumination light is used in barcode readers, then the illumination intensity is sufficient at near working distances, but the illumination intensity diminishes at far working distances
Solution Approach 1:
The window is divided into two distinct portions: a first window-portion with a first divergence angle (at least 25 degrees along the first plane) for far working distances, and a second window-portion with a second divergence angle (at most 20 degrees along the first plane) for near working distances. This segmentation allows the illumination assembly to provide appropriate illumination intensity across the full range of operable distances by directing different portions of light through different window portions.
Solution Approach 2:
Different portions of the window are assigned different optical properties (divergence angles) to serve different functional requirements. The first window-portion provides wider divergence for far distances where light needs to spread more, while the second window-portion provides narrower divergence for near distances where concentrated illumination is needed. This local differentiation of optical characteristics resolves the contradiction between near and far working distance performance.
2Adaptability or versatility
If the illumination light is collimated for far working distances, then the illumination is adequate at far ranges, but the divergence is insufficient for near working distances
Solution Approach 1:
The window is segmented into two portions with different divergence characteristics. The first window-portion provides wider divergence (at least 25 degrees along the first plane) suitable for near working distances, while the second window-portion provides controlled divergence (at most 20 degrees along the first plane) suitable for far working distances. This segmentation enables the system to adapt to both near and far ranges effectively.
Solution Approach 2:
The illumination assembly dynamically adapts to different working distances by utilizing different window portions based on the required divergence. The system transitions between using the first window-portion for near distances requiring wider divergence and the second window-portion for far distances requiring more collimated light, providing dynamic adaptability across the full operable range.
3Device complexity
If a single divergence angle is used for the illumination light, then the device structure is simple, but the illumination performance varies across different working distances
Solution Approach 1:
The window is divided into two portions with different divergence angles to optimize illumination performance across varying working distances. While this increases structural complexity compared to a single-window design, it significantly improves reliability by ensuring consistent illumination performance whether the barcode reader is used at near or far distances. The segmented approach resolves the trade-off by providing distance-appropriate illumination characteristics.
Solution Approach 2:
Different regions of the window are assigned different optical properties (divergence angles) to match the specific requirements of different working distances. The first window-portion serves near distances with wider divergence, while the second window-portion serves far distances with narrower divergence. This local differentiation improves overall system reliability across the full operable 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 provides enhanced illumination patterns with a higher radiant intensity in the horizontal direction and controlled divergence, effectively illuminating targets across the full range of a barcode reader's operable distance, improving decoding accuracy.
Implementation Method 1
a lens positioned within the first path of the illumination light, the lens configured to redirect the central axis resulting in a redirected central axis and propagate the illumination light along a second path
Implementation Method 2
the first window-portion being configured to propagate a first portion of the illumination light along a third path, the first portion of the illumination light being a portion of the illumination light that impinges on the first window-portion, the third path having a divergence angle of at least 25 degrees along the first plane
Implementation Method 3
the second window-portion configured to propagate a second portion of the illumination light along a fourth path, the second portion of the illumination light being a portion of the illumination light that impinges on the second window-portion, the fourth path having a divergence angle of at most 20 degrees along the first plane
Data Source
AI summary
At least some embodiments of the present invention are directed toward optical arrangements for use in providing illumination light emitted by a barcode reader. In some embodiments, the arrangement includes an illumination source, a lens positioned within the path of the illumination light emitted by the illumination source where the lens is operable to collimate the light and redirect its central axis, and a window positioned within the path of the redirected and collimated light where the window is operable to alter the illumination light such that the resulting illumination light beam has a height-to-width ratio of less than 8 to 25.