PURPOSE: To determine the absolute position of an elevator cage by using two ultrasonic converters and measuring the elapse time until one converter receives other response signal from transmission.
CONSTITUTION: The measurement of a position is started by the start signal of a cage control unit 10 and the ceiling converter 7 attached to a ceiling 4 transmits a probe signal 19 to the cage converter 12 attached to the roof of a cage 1. When the converter 12 receives the probe signal 19, a remote echo 22 is delayed in order to avoid the ultrasonic echoes from the walls 5, 6 of a lift passage to transmit a response signal 20 of the same amplitude and the same frequency. The converter 7 receives the signal 20 to generate a stop signal. A time and distance detection circuit 11 responds to a start signal and a stop signal not containing the near echo 21 from a lift rope due to a ceiling converter circuit 8 to measure the running times of the signals 19, 20 and the running times are multiplied by those speeds to calculate the distance between the converters 7, 12. By this constitution, the absolute position of the cage 1 is determined.
KURAUSU DEISHIYUTEREERU
RORUFU EEBERUHARUTO HANICHIE
