Annular Light Guide Illuminator for Optical Scanner

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Solution Overview

Problem

Conventional optical scanners face challenges in providing homogeneous and sufficient light intensity for illuminating a zone on an item's reflective surface, leading to issues with stray light and 'hot spots' that degrade image quality, especially on curved surfaces.

Innovation Solution

An annular light guide illuminator is used, which guides light without internal reflection and features a tapered exit surface to minimize stray light, ensuring uniform illumination and enhancing contrast by concentrating light on the target zone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional light sources are used to illuminate the zone, then sufficient light intensity is provided, but stray light and hot spots are generated that degrade image quality

Engineering Contradiction:

Improvelight intensityVSAvoidstray light

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The illumination system is segmented into multiple LED light sources arranged in a specific pattern, with each LED contributing to different regions of the illuminated zone. This segmentation allows for distributed illumination that reduces hot spots and stray light while maintaining sufficient overall light intensity for marking detection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the illumination system are designed with different characteristics - the LED arrangement and optical elements are configured to provide uniform illumination quality across the target zone, minimizing areas of excessive brightness (hot spots) and stray light while ensuring adequate illumination for contrast detection.

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If conventional illuminators are used, then light delivery is achieved, but non-uniform illumination with hot spots occurs on reflective surfaces

Engineering Contradiction:

Improveillumination uniformityVSAvoidillumination uniformity

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The illumination system uses multiple segmented LED sources rather than a single conventional illuminator, allowing each segment to contribute to different portions of the illuminated area. This enables more uniform light distribution across reflective surfaces by eliminating concentrated hot spots.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The LED array is arranged in a two-dimensional pattern rather than using a conventional point-source illuminator, distributing light delivery across multiple spatial dimensions. This dimensional approach to illumination creates more uniform lighting on curved and reflective surfaces by eliminating single-point concentration effects.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of operation

If hand-held scanner design is implemented, then portability is achieved, but stable illumination control becomes more difficult

Engineering Contradiction:

ImproveportabilityVSAvoidillumination stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The illumination system incorporates controllable LED elements that can be dynamically adjusted in intensity and activation patterns. This dynamic control allows the portable scanner to maintain reliable and stable illumination conditions despite movement, by adapting the light output to compensate for changing distances and angles to the target surface.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system can change illumination parameters such as LED current, voltage, and individual LED activation states to maintain consistent illumination quality. These parameter adjustments ensure reliable operation of the hand-held scanner across varying operational conditions, distances, and surface orientations.

Inventive Principle:

Principle #35Parameter changes

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 annular light guide illuminator effectively reduces stray light and enhances marking detection by providing homogeneous illumination, improving contrast and readability of markings on both flat and curved surfaces.

Implementation Method 1

an annular light guide illuminator (10) for illuminating a zone (17) on a reflective surface, comprising: a light source (11) for generating light; an annular light guide (13) for guiding said light without internal reflection

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

an exit surface (16) for refracting light toward said zone (17)

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentEP2414987B1Annular light guide illuminator and optical scanner

Publication Date: 2017.06.28 SICPA HOLDING SA

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AI summary

The disclosed annular light guide illuminator (10) is operable to guide light from its entry surface (12) to its exit surface (16) for illuminating a zone (17) at its distal end (19), and comprises a truncated-cone-shaped inner cavity (18) of which base opens onto said distal end (19), and of which truncated summit (20) opposite to said base opens onto an inner hole portion (21) for back transmitting light reflected/emitted from said zone. An optical scanner implementing said illuminator is also disclosed.