Optical Sensor UV Detection Transparent Objects

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Solution Overview

Problem

Existing optical sensor devices and methods for detecting transparent objects are unreliable due to low Fresnel reflections under perpendicular light incidence, leading to weak signal components and interference from factors like dirt and temperature fluctuations, and oblique alignment increases installation space and causes glare reflections.

Innovation Solution

The use of a sensor device with a transmitted light beam containing ultraviolet radiation and a receiving unit insensitive to UV, combined with a wavelength converter that absorbs UV radiation and emits light with a longer wavelength, allowing for reliable detection of transparent objects by eliminating direct reflections and providing clear switching points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If perpendicular light incidence is used for detecting transparent objects, then the signal component is weak due to low Fresnel reflections, but aligning the sensor at an angle increases Fresnel reflections and improves detection reliability

Engineering Contradiction:
Improvedetection reliabilityVSAvoidsignal strength
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the wavelength parameter of the transmitted light beam from visible light to ultraviolet radiation. Transparent objects absorb UV radiation strongly, creating high attenuation and clear switching points for detection, eliminating the need for oblique alignment while maintaining detection reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of UV absorption by transparent objects into a beneficial detection mechanism. The strong attenuation of UV radiation by transparent objects, which would normally be a loss, becomes the basis for reliable detection with clear switching points

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If oblique alignment is used to increase Fresnel reflections, then detection reliability improves, but installation space increases and glare reflections occur at edges

Engineering Contradiction:
Improvedetection reliabilityVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent changes the wavelength parameter from visible light to ultraviolet radiation, allowing perpendicular alignment instead of oblique alignment. This reduces the installation space required while maintaining detection reliability through strong UV attenuation by transparent objects

Inventive Principle:
Principle #35Parameter changes

3Reliability

If oblique alignment is used to increase Fresnel reflections, then detection reliability improves, but glare reflections occur at edges leading to false triggering

Engineering Contradiction:
Improvedetection reliabilityVSAvoidglare reflections
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the wavelength from visible light to ultraviolet radiation. Transparent objects absorb UV radiation strongly, eliminating glare reflections that occur with visible light at oblique angles, thus preventing false triggering while maintaining detection reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the strong absorption of UV radiation by transparent objects, which causes signal loss in traditional systems, into a beneficial effect that eliminates glare reflections and provides clear switching points for reliable detection

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Measurement precision

If visible light is used for detection, then the receiving unit can detect the light beam, but transparent objects cause weak signals due to high transmission

Engineering Contradiction:
Improvesignal detection capabilityVSAvoidobject perception reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent changes the wavelength parameter of the light beam from visible light to ultraviolet radiation. Transparent objects absorb UV radiation strongly, transforming the high transmission problem into high attenuation, which provides reliable detection signals

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

This approach enables reliable detection of transparent objects, such as plastic bottles or foils, by utilizing the high attenuation of UV radiation, reducing interference and ensuring accurate object perception with defined switching points, even at high transport speeds.

Implementation Method 1

a wavelength converter, which is designed to at least partially absorb the transmitted light beam and, due to the absorption, to emit the received light beam with a wavelength greater than ultraviolet radiation

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

the wavelength converter, which is designed to at least partially absorb the transmitted light beam and, due to the absorption, to emit the received light beam with a wavelength greater than ultraviolet radiation

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 3

transparent objects, in particular made of plastics, absorb ultraviolet radiation, also called ultraviolet light or UV light or black light, to a very great extent

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 4

a receiving unit that is designed to receive a received light beam

Methodology Applied
Scientific EffectPhotoelectric Effect: Photoelectric Effect

Data Source

PatentEP3029493B1Optical sensor device, assembly with the same and method for perception of transparent objects
Publication Date: 2021.06.16 BAUMER ELECTRIC AG
  • EP3029493B1 patent drawingFigure 1

AI summary

The present invention relates to an optical sensor device (2) for object detection, in particular for the detection of transparent objects (4), comprising a transmitter unit (5) configured to emit a transmitting light beam (S) and a receiver unit (6) configured to receive a receiving light beam (E). The invention further relates to an arrangement (1) for object detection, in particular a light barrier arrangement for the detection of transparent objects (4). The invention also relates to a method for object detection, in particular for the detection of transparent objects (4), wherein a transmitting light beam (S) is emitted by a transmitter unit (5) and a receiving light beam (E) is received by a receiver unit (6).In order to be able to reliably perceive particularly transparent objects (4), the invention provides that the transmitting light beam (S) contains ultraviolet radiation and that the receiving unit (6) is insensitive to ultraviolet radiation in the receiving light beam (E), or that the transmitting light beam (S) is at least partially absorbed by the wavelength converter (3) and, due to the absorption, the receiving light beam (E) is emitted with a wavelength greater than ultraviolet radiation.