Elevator hatch door monitoring system

An elevator shaft door monitoring system which determines if any door to an elevator shaft at any floor along the elevator shaft is opened while an elevator cab is away from the door, comprising:

• at least two non-contact door monitors being provided at a floor, each door monitor being mounted in the shaft at a respective location generally opposite each door being monitored along the shaft, each such door monitor being directed at the respective door and detecting the opening of the respective door without direct contact therewith, whereby one door monitor monitors a hatch door at the floor and the other door monitor monitors the presence of the elevator cab, each door monitor produces an alarm signal whenever a respective door is being opened and the elevator cab is not at the floor where the door is being opened on the basis of a distance signal produced by each door monitor whereby the distance is determined from the respective door monitor to an object;
• a preprogrammed microprocessor for receiving the alarm signals and distance signals from each door monitor and indicating an alarm condition whenever an alarm signal is received;
• and
• a local area network connecting each monitor to the microprocessor whereby each door monitor has an interface circuit connected between it and the network.

An elevator shaft door monitoring system which determines if any door to an elevator shaft at any floor along the elevator shaft is opened while an elevator cab is away from the door, comprising:

• a plurality of non-contact door monitors, each door monitor being mounted in the shaft at a respective location generally opposite each door being monitored along the shaft, each such door monitor being directed at the respective door and detecting the opening of the respective door without direct contact therewith, and producing an alarm signal whenever the respective door is being opened and the elevator cab is not at the floor where the door is being opened;
• a control circuit for receiving the alarm signals from the door monitors and indicating an alarm condition whenever an alarm signal is received;
• an elevator shut down circuit wherein the alarm signal acts to operate the elevator shut down circuit and take the elevator out of service;
• and
• at least one of a smoke detector and fire detector, operation of at least one of said smoke and fire detectors acting to inhibit operation of the elevator shut down circuit.