Self correcting infrared intrusion detection system

A system for detecting intrusions within a monitored space, said system comprising:

• a plurality of spaced apart transmitter stations for radiating signals across said space;
• a plurality of spaced apart receiver stations for detecting the presence or absence of signals radiated by said transmitters;
• circuit means for sequentially activating said transmitter stations and sequentially polling said receiver stations to monitor a plurality of beams across said space, wherein the interruption of a beam generally indicates an intrusion;
• and,
• means for determining and marking out inoperative beams so that said system continues to function and monitor said space even though particular beams normally established by said system have ceased at least temporarily.

An intrusion detection system for elevators comprising a pair of sliding doors with an elevator car entrance way disposed therebetween, said system comprising:

• a plurality of spaced apart transmitter circuits adapted to be secured to a first one of said doors, each transmitter circuit comprising at least one infrared transmitter station for radiating modulated light across said entrance way toward the other door;
• a plurality of spaced apart receiver circuits adapted to be secured to said other door, each receiver circuit comprising at least one receiver station for detecting the presence or absence of modulated infrared signals;
• micro controller means for sequentially activating said receiver stations and said transmitter stations to establish and monitor a plurality of through beams extending between said doors, said micro controller means interconnected with each of said transmitter circuits through a transmitter bus and to each of said receiver circuits through a receiver bus;
• and,
• means for establishing a long beam pattern or a short beam pattern, and operable to switch between said long and short beam patterns depending upon the spacing of said doors.

An intrusion detection system for elevators comprising a pair of sliding doors with an elevator car entrance way disposed therebetween, said system comprising:

• a plurality of spaced apart, transmitter circuits adapted to be secured to a first one of said doors, each transmitter circuit comprising at least one infrared transmitter station for radiating modulated light across said entrance way toward the other door;
• a plurality of spaced apart, receiver circuits adapted to be secured to said other door, each receiver circuit comprising at least one receiver station for detecting the presence or absence of modulated infrared signals;
• micro controller means for sequentially activating said receiver stations and said transmitter stations to establish and monitor a plurality of through beams extending between said doors, said micro controller means interconnected with each of said transmitter circuits and said receiver circuits;
• wherein said micro controller means determines and marks out those transmitter stations and/or receiver stations which are at least temporarily inoperative, so that said system continues to function and monitor said doors even though certain beams have been semi-permanently obstructed.

A method for monitoring a space and detecting intrusions therewithin, said method comprising the steps of:

• sequentially radiating signals across said space with a plurality of transmitters;
• sequentially sensing for said signals with a plurality of spaced apart receivers disposed along an opposite side of said space;
• determining the presence or absence of an intrusion in accordance with the establishment or blockage of beams between said transmitters and receivers;
• and,
• executing either a long beam pattern or a short beam pattern depending upon the width of said space.

An intrusion detection method for monitoring a space such as the area between elevator doors and for and detecting intrusions therewithin, said method comprising the steps of:

• establishing a redundant number of beam pathways across said space;
• determining the presence or absence of an intrusion in accordance with the blockage of said beam pathways;
• periodically testing for inoperative beam pathways;
• and,
• marking out inoperative beam pathways without disturbing said determining step.

An intrusion detection method for monitoring a space such as the area between elevator doors and for and detecting intrusions therewithin, said method comprising the steps of:

• sequentially radiating signals across said space with a plurality of transmitters;
• sequentially sensing for said signals with a plurality of receivers;
• determining the presence or absence of an intrusion in accordance with the establishment or blockage of beams established between said transmitters and said receivers;
• periodically testing for inoperative receivers and transmitters;
• and,
• at least temporarily marking out inoperative transmitters and/or receivers without disturbing said determining step.