| 摘要 |
<p>The present invention relates to an apparatus for detecting any abnormality in a cage of an elevator, characterized by comprising a transmitter which continuously transmits an ultrasonic wave inwardly of the cage of the elevator, a receiver which receives an ultrasonic wave retrogressing in such a manner that the ultrasonic wave transmitted from said transmitter is reflected by an object within the cage, and a processing circuit which detects the rate of movement of the object within the cage on the basis of a magnitude difference between frequencies of the ultrasonic waves of said transmitter and said receiver and which decides that an abnormality has occurred in the cage when the difference frequency has become at least a preset value.</p> |
