Optoelectronic Sensor Transparent Light Guide Stray Light

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Solution Overview

Problem

Existing optoelectronic sensors face issues with asymmetrical light spots, which negatively affect detection properties, and require significant installation space and suffer from stray light loss due to mirror surfaces or boundary surfaces.

Innovation Solution

An optoelectronic sensor design featuring a transparent light guide that directs transmitted light to a reference receiver via an aperture, minimizing installation space and maintaining beam cross-section integrity, with the light guide based on total reflection and optionally including geometric or refractive structures, and integrated with a screen to prevent stray light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If mirror surfaces or boundary surfaces are used for light transmission, then light can be redirected, but installation space is increased and stray light is lost

Engineering Contradiction:
Improvestray light lossVSAvoidinstallation space
Core Design Contradiction:
Loss of energyVSVolume of stationary object

Solution Approach 1:

The patent combines the light guide function and aperture function into a single optical element. The aperture is integrated directly into the light guide structure, eliminating the need for separate mirror surfaces or boundary surfaces for light redirection. This merging reduces installation space while maintaining light transmission efficiency and reducing stray light loss.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light guide acts as an intermediary component that directs transmitted light to the reference receiver through total internal reflection at its boundaries, rather than using mirror surfaces. This intermediary structure minimizes installation space requirements while preventing stray light loss that would occur with traditional mirror-based approaches.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If existing decoupling methods are used, then light can be separated from the transmission path, but the light spot becomes asymmetrical affecting detection properties

Engineering Contradiction:
Improvelight spot symmetryVSAvoiddetection properties
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies local quality by creating a specific geometric structure within the light guide that selectively directs light. The aperture is positioned and dimensioned to allow only symmetric light paths to reach the reference receiver, while blocking asymmetric paths. This local structural feature ensures light spot symmetry is maintained, improving detection properties.

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If multiple separate components are used for light guiding and stray light prevention, then functions can be specialized, but device complexity and assembly are increased

Engineering Contradiction:
Improveassembly simplicityVSAvoidpart count
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent merges the light guide and aperture into a single integrated optical element. This combination reduces the total part count and simplifies assembly procedures, as fewer components need to be manufactured, handled, and assembled. The integrated design maintains specialized functions while reducing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The optical element serves multiple functions simultaneously: it guides light through total internal reflection, defines the aperture opening, and prevents stray light entry. This multi-functionality reduces the need for separate specialized components, thereby reducing device complexity and assembly complexity while maintaining manufacturing ease.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 design minimizes installation space, maintains beam integrity, reduces part count, and simplifies assembly, achieving precise and stable light spot detection with reduced stray light, enhancing the sensor's detection capabilities.

Implementation Method 1

the light guide based on total reflection

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3798686B1Optoelectronic sensor
Publication Date: 2022.04.06 SICK AG
  • EP3798686B1 patent drawingFigure 1
  • EP3798686B1 patent drawingFigure 2
  • EP3798686B1 patent drawingFigure 3~4

AI summary

Optoelectronic sensor (1) for detecting objects (2) in a monitoring area (3), comprising a light transmitter (4) for emitting transmitted light (5), a light receiver (6) for generating a received signal from transmitted light (5) reflected by objects (2) in the monitoring area, a control and evaluation unit (8) for determining information about objects (2) in the monitoring area (3) on the basis of the received signal, and an optical element (9) which is arranged in the beam path of the transmitted light (5) of the light transmitter (4) such that a part of the transmitted light (5) enters the monitoring area (3) as detection light, wherein the optical element (9) has a transparent light guide (10) which directs a part of the transmitted light (5) to a reference light receiver (11), and the optical element (9) has an aperture (12) with an opening (13) for the transmitted light (5).Optical element (9) which is arranged in the beam path of transmitted light (5) of a light transmitter (4) such that part of the transmitted light (5) enters a monitoring area (3) as detection light, wherein the optical element (9) has a transparent light guide (10) which directs part of the transmitted light (5) to a reference light receiver (11) and the optical element (9) has a diaphragm (12) with an opening (13) for the transmitted light (5).