Double Ray Laser Lighting Grid for Crosstalk Reduction

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Solution Overview

Problem

Existing light grids for contactless object detection in surveillance areas face issues with optical crosstalk, requiring a large number of light transmitters and receivers, leading to increased production costs and longer inspection times due to sequential activation of light beams, which compromises detection capability and reaction time.

Innovation Solution

Implementing a double light beam arrangement where two adjacent light transmitters form a pair with one light receiver or one light transmitter pairs with two adjacent receivers, allowing for separate activation of light beams with distinct spectral or polarization properties, and using pupil division to ensure non-interfering optical paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a large number of light transmitters and receivers are used to ensure detection capability, then the detection capability is improved, but the production costs increase

Engineering Contradiction:
Improvedetection capabilityVSAvoidnumber of light transmitters and receivers
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent combines multiple light beams into a single common optical path by merging adjacent light transmitters or receivers. This allows multiple detection channels to share common optical components (lenses, filters, detectors), reducing the total number of components while maintaining detection capability across the entire monitoring area.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent designs optical components to serve multiple functions simultaneously. A single light transmitter can generate multiple light beams for different detection channels, and a single receiver can detect light from multiple transmitters. This multi-functionality reduces the overall component count while preserving detection capability.

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

2Reliability

If light transmitters and receivers are activated sequentially in pairs to avoid optical crosstalk, then optical crosstalk is eliminated, but the inspection time increases

Engineering Contradiction:
Improveoptical crosstalk eliminationVSAvoidinspection time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent employs periodic activation of light transmitters and receivers in a cyclic sequence rather than strict sequential pairing. By organizing multiple transmitters and receivers into synchronized groups that activate in periodic cycles, the system eliminates optical crosstalk through temporal separation while reducing total inspection time through parallel processing of multiple detection channels within each cycle.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent implements dynamic control of light beam activation, where the activation pattern adapts based on detected objects or priority levels. High-priority detection zones can trigger immediate responses while maintaining crosstalk avoidance, and the system dynamically adjusts activation sequences to minimize inspection time while preserving reliability.

Inventive Principle:
Principle #15Dynamics

3Area of stationary object

If the distance between light transmitters and receivers is increased, then the coverage area is expanded, but optical crosstalk increases

Engineering Contradiction:
Improvecoverage areaVSAvoidoptical crosstalk
Core Design Contradiction:
Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent addresses optical crosstalk by introducing spectral dimension separation. Different light beams are assigned different wavelengths or frequency ranges, allowing transmitters and receivers to operate simultaneously without interference. This spectral dimensionality enables expanded coverage distances while maintaining signal discrimination and eliminating crosstalk through wavelength-specific detection.

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

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 reduces the number of light emitters/receivers needed without compromising detection capability, lowering production costs and shortening inspection times while minimizing the risk of optical crosstalk.

Implementation Method 1

several light transmitters are arranged next to one another on one side of the monitored area and several light receivers are arranged next to one another on the opposite side of the monitored area. The light transmitters and light receivers are activated in pairs, sequentially and cyclically by a control unit, so that the monitoring area is penetrated by a plurality of light beams

Methodology Applied
Scientific EffectLight propagation: Light

Implementation Method 2

a possible object within the monitored area then interrupts the light path from a light emitter to a light receiver

Methodology Applied
Scientific EffectPhotodetection: Photoelectric Effect

Data Source

PatentEP2144091B1Double ray laser for lighting grid
Publication Date: 2011.03.09 SICK AG
  • EP2144091B1 patent drawingFigure 1~2
  • EP2144091B1 patent drawingFigure 3~4

AI summary

The method involves arranging light transmitters (1-5) next to each other at an edge (A) of a monitoring area (U), and arranging light receivers (41, 42) next to each other at another edge (B) of the area. The area is permeated with light beams (21-25) that are parallel to each other. Two adjacent light transmitters with one light receiver or two adjacent light receivers with one light transmitter form a dual light beam arrangement. Light beams of the arrangement are separated by the unit or activated together, and exhibit optical beam characteristics that do not affect each other. An independent claim is also included for an optoelectronic sensor designed as a lighting grid for contactless detection of an object with a monitoring area, comprising an optical filter.