Multi-beam Light Barrier Beam Folding Mirror Lens

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Solution Overview

Problem

Multi-beam light barriers face a challenge in achieving long ranges while maintaining a compact housing size, as longer focal lengths and larger apertures increase the housing size and installation space requirements, and beam folding with prisms is costly and inefficient at steeper angles.

Innovation Solution

A multi-beam light barrier design that uses a mirror for beam deflection, with a lens extending more in the housing's longitudinal direction than transversely, allowing for increased focal length without increasing housing size, and incorporates a printed circuit board and intermediate screen to manage light reflections, enabling efficient beam folding and reduced manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If long focal lengths and large apertures are used to increase range, then range is improved, but housing size increases

Engineering Contradiction:
ImproverangeVSAvoidhousing size
Core Design Contradiction:
Length of stationary objectVSVolume of stationary object

Solution Approach 1:

The patent introduces a beam folding mechanism that changes the optical path from a straight linear arrangement to a folded path within the housing. The light beam is reflected multiple times inside the housing, allowing the effective optical path length to exceed the physical housing dimensions. This enables long focal lengths to be achieved without proportionally increasing housing volume.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Length of stationary object

If beam folding with prisms is used to extend range, then range is improved, but manufacturing cost increases

Engineering Contradiction:
ImproverangeVSAvoidmanufacturing cost
Core Design Contradiction:
Length of stationary objectVSEase of manufacture

Solution Approach 1:

The patent replaces expensive precision prisms with simpler, cheaper reflective surfaces. These can be standard mirrors or even reflective coatings applied to internal housing surfaces, significantly reducing manufacturing costs while achieving the same beam folding effect. The solution uses readily available components rather than specialized optical elements.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Length of stationary object

If beam folding with prisms is used to extend range, then range is improved, but efficiency decreases at steeper angles

Engineering Contradiction:
ImproverangeVSAvoidlight loss
Core Design Contradiction:
Length of stationary objectVSLoss of energy

Solution Approach 1:

The patent extracts the beam folding function from complex prisms and implements it using simple reflective surfaces with controlled angles. By carefully designing the reflection angles and using anti-reflective coatings where appropriate, the system minimizes light loss at each reflection point, maintaining high efficiency even with multiple reflections required for steep angle beam folding.

Inventive Principle:
Principle #2Taking out (Extraction)

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 solution allows for a compact, cost-effective multi-beam light barrier with extended range capabilities, optimizing installation space and reducing manufacturing costs while maintaining robustness and precision in opto-mechanical alignment.

Implementation Method 1

at least one mirror (16) which is arranged as a deflection unit for the transmitted light beams (6) and/or received light beams (10) at a distance in front of the transmitting element (8) and/or receiving element (12)

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

each with a lens (14), which is arranged in front of the transmitting element (8) and/or receiving element (12)

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3324218B1Multi-beam light barrier
Publication Date: 2019.08.28 SICK AG
  • EP3324218B1 patent drawingFigure 1~2
  • EP3324218B1 patent drawingFigure 3~5
  • EP3324218B1 patent drawingFigure 5.1

AI summary

Multi-beam light barrier (1) for detecting objects (2) in a monitoring area (3) comprising at least one housing (4) with a housing longitudinal axis (5), with at least one transmitter module (7) emitting a transmitting light beam (6) with a transmitting element (8) and with a control unit (9) for controlling the transmitter module (7) and/or at least one receiver module (11) receiving a receiving light beam (10) with a receiving element (12) and with an evaluation unit (13) for generating an object detection signal depending on received signals present at the output of the receiver module (11), with a lens (14) in each case, which is arranged along the beam path in front of the transmitting element (8) and/or the receiving element (12), with a circuit board (15) on which the transmitting elements (8) and/or receiving elements (12) are arranged,wherein at least one mirror (16) is arranged as a deflecting unit (19) for the transmitting light rays (6) and/or the receiving light rays (10) at a distance in front of the transmitting element (8) and/or receiving element (12), wherein the mirror (16) is arranged along the beam path (21) between the lens (14) and the transmitting element (8) or between the lens (14) and the receiving element (12), and the lens (14) has a larger extent in the direction of the longitudinal axis (5) of the housing than transversely to the longitudinal axis (5) of the housing.