Cascading Optical Units Gap-Free Light Curtain

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Solution Overview

Problem

Conventional light curtains often leave gaps in the protective field when cascading optical units, leading to potential safety hazards and increased costs due to complex and expensive arrangements.

Innovation Solution

The solution involves arranging radiation emitting and receiving elements within an elongated support element forming an outer housing of the optical unit, allowing abutting assembly without gaps, using end caps for precise alignment and mechanical fixing, and incorporating plug-in units for electrical connection, enabling seamless cascading of optical units without gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical units are cascaded using cables and plug connectors at end portions, then electrical connection is achieved, but a significant area remains unguarded in the region where two optical units are joined together

Engineering Contradiction:
Improveprotective field continuityVSAvoidconnection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the cable exit position with the radiation emitting/receiving elements by positioning the cable exit at the end portion of the housing that coincides with the location of outermost radiation elements. This integration eliminates the gap between optical units when cascaded, ensuring continuous protective field coverage while maintaining electrical connection functionality.

Inventive Principle:
Principle #5Merging (Combining)

2Area of stationary object

If conventional cascading arrangements are used to cover larger areas, then coverage area is increased, but gaps appear in the protective field at joining regions

Engineering Contradiction:
Improveprotected areaVSAvoidprotective field continuity
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The patent applies local quality by positioning the cable exit specifically at the end portion of the housing where the outermost radiation elements are located. This localized positioning ensures that when optical units are cascaded, the cable exit region aligns perfectly with the radiation element region, creating continuous coverage at the joining areas while maintaining the overall extended coverage capability.

Inventive Principle:
Principle #3Local quality

3Area of stationary object

If optical units are arranged in series to protect larger areas, then coverage is extended, but alignment precision deteriorates

Engineering Contradiction:
Improveprotected areaVSAvoidalignment precision
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent creates universal end portions of the housing that serve multiple functions: they provide structural support, ensure precise alignment when cascaded, and position the cable exit at the optimal location for continuous coverage. This standardized multi-functional design allows optical units to be reliably cascaded in series to extend coverage area while maintaining consistent alignment precision across all joining points.

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 approach ensures a continuous, gap-free light screen with accurate alignment and synchronization, compatible with existing assemblies, providing comprehensive protection without extensive integral housings and reducing costs.

Implementation Method 1

The LEDs transmit modulated infrared light beams along separate parallel channels to the PTs at the receiver bar

Methodology Applied
Scientific EffectLight transmission: Light

Implementation Method 2

If one or more beams are blocked from penetration by an opaque object, such as the operator's arm, a control circuit shuts down the machine

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3051320B1Cascading of optical units of a light curtain
Publication Date: 2018.11.28 ROCKWELL AUTOMATION SAFETY
  • EP3051320B1 patent drawingFigure 1
  • EP3051320B1 patent drawingFigure 2
  • EP3051320B1 patent drawingFigure 3

AI summary

The present invention relates to light curtains, in particular safety light curtains, for monitoring a protective field. Furthermore, the present invention relates to optical units which are part of such a light curtain. According to the present invention, an optical unit (105) comprises a plurality of radiation emitting and/or radiation receiving elements (116, 118, 120) for transmitting and/or receiving radiation beams forming said light curtain (100), and an elongated support element (160) forming an outer housing of said optical unit, said support element having two opposing peripheral regions which are formed to allow an abutting assembly with another identical optical unit. Said radiation emitting and/or radiation receiving elements are arranged within said support element to form a row, and wherein at least one peripheral one of said radiation emitting and/or radiation receiving elements is located directly adjacent to an outer wall of at least one of said peripheral regions of the support element.