US 7,741,595 B2Granted

Light grid for detecting objects in a monitored zone

AssigneeLeuze Lumiflex GmbH & Co. KG

InventorsLutz Lohmann, Gennadiy Tkach, Joachim Koperski

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Abstract

A light grid detects includes a number of light emitting transmitters. The transmitted light rays of the individual transmitters are imprinted with a code that characterizes the transmitted light rays. The transmitters are activated cyclically and successively. Corresponding receivers aligned with the transmitters form transmitter/receiver pairs. The receivers are activated continuously for reception of the transmitted light rays. An evaluation unit coupled to the receiver outputs generates an object detection signal in dependence on the signals received at the receiver outputs. The received signals are conducted in parallel to evaluation unit inputs. Only the received signals associated with the active transmitter are recorded and stored in the evaluation unit by muting the inputs onto which the signals received by the remaining receivers are conducted. The correctness of the codes transmitted by the transmitters and their sequence are checked in the evaluation unit by evaluating the stored received signals.

Claims18

Dependent claims

A method for detecting objects within a monitoring zone of a light grid including a predetermined number of transmitters transmitting light rays, a corresponding number of receivers respectively aligned with the transmitters, each aligned transmitter and receiver forming a beam axis each receiver having a receiver output and producing a received signal at the output, and an evaluation unit for generating an object detection signal in dependence on the received signals, wherein the received signals are coupled to separate, parallel inputs of the evaluation unit, the method comprising:

cyclically activating the transmitters, one after another;
impressing characterizing codes on the transmitting light rays of the individual transmitters;
simultaneously activating the receivers such that only the received signal from the receiver corresponding to the activated transmitter is recorded and stored in the evaluation unit by muting the inputs of the evaluation unit to which the received signals from the remaining receivers are coupled;
verifying the correctness of the codes impressed on the transmitting light rays by evaluating the stored received signals in the evaluation unit;
and
verifying the sequence of received transmitting light rays by evaluating the stored received signals in the evaluation unit.

3 more elements

Dependencies are inferred from the claim text.