Optical Surveillance Reflection Light Probe Binary Detection

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Solution Overview

Problem

Existing optical surveillance methods struggle with robust detection of objects, especially those with specular or multi-specular surfaces, as they are heavily dependent on the surface condition of the object, leading to inaccurate position information due to high-contrast effects.

Innovation Solution

A method using two light receivers with separate detection zones and logical signal processing, where each receiver generates binary output signals based on whether the center of gravity of reflected light falls within its zone, allowing for independent evaluation and logical combination to produce an object detection signal, eliminating the need for identical displacement compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If two position-sensitive receiving elements are arranged symmetrically to compensate for high-contrast object effects, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveposition information accuracyVSAvoidreceiver arrangement complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the detection task into two independent binary evaluation stages: first evaluating each light receiver independently to determine presence/absence, then combining results logically. This segmentation avoids the complexity of symmetric arrangements while maintaining robustness against surface condition variations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts the essential detection function from complex symmetric arrangements by using only two light receivers with binary evaluation. The position information is extracted only as presence/absence data, eliminating the need for complex position compensation mechanisms.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If binary output signals with logical combination are used instead of position information, then reliability of object detection is improved, but measurement precision is reduced

Engineering Contradiction:
Improvedetection robustnessVSAvoidposition information accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses simple binary presence/absence detection instead of precise position measurement, analogous to using a simple, reliable indicator rather than a complex measurement instrument. This binary approach is sufficiently robust for detection purposes while avoiding the complexities of precise position measurement.

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

Solution Approach 2:

The patent replaces the mechanical/physical system of position-sensitive detection with a logical/electronic system of binary signal combination. This substitution achieves robust detection through logical operations rather than precise physical measurement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 provides a more robust and less surface-condition-dependent object detection, effectively identifying objects with critical surfaces by ensuring accurate presence or absence signals regardless of surface quality, even in scenarios where residual reflection is insufficient for triangulation.

Implementation Method 1

light is sent through a transmission optics into the surveillance area. The light is reflected or re-emitted back from an object that may be located in the surveillance space

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

Depending on whether the object is closer or further away from the transmitter/receiver arrangement, the light that is reflected back or emitted back hits the light receiver at a different point according to the triangulation principle

Methodology Applied
Scientific EffectTriangulation: Parallax

Implementation Method 3

The two detection zones can be formed, for example, by one or more elements of a row of photodiodes. The output signal of a light receiver can be, for example, the difference in the photo currents that are supplied by the two detection zones

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP2434311B1Method for optical monitoring of a surveillance area and reflection light probe
Publication Date: 2014.07.16 SICK AG
  • EP2434311B1 patent drawingFigure 1

AI summary

The invention relates to a method for the optical monitoring of a monitoring area, in which light is sent into the monitoring area and light reflected or remitted from the monitoring area is detected by a first and a second light receiver, each having two spatial detection zones for the sensing area and the background area of ​​the monitoring space. According to the invention, a first output signal of the first light receiver is generated depending on whether the center of gravity of the reflected/remitted light is located in the first or the second detection zone of the first light receiver, wherein the first output signal can only assume one of two possible states.A second output signal from the second light receiver is generated depending on whether the center of gravity of the reflected/remitted light is located in the first or the second detection zone of the second light receiver, whereby the second output signal can only assume one of two possible states. The first and second output signals are logically combined to generate an object detection signal. The invention further relates to a photoelectric sensor with which the method according to the invention can be carried out.