DEFLECTION SENSOR

PURPOSE:To provide a deflection sensor which can sense the one-direction deflecting amount and rotational deflecting amount of a hanging tool quickly and accurately and which enables effective deflection stop control. CONSTITUTION:A deflection sensor is equipped with a target 4 hung down by a wire 2 and marked with a band-shaped marker 4a installed on the hanging tool 3 of a crane, a camera 5 installed upon a crane trolley 1 to photograph the motion of the marker 4a on the target 4, and an image processing device to make processing of the images photographed by the camera 5 from time to time. Using the output signal from this image processing device as a reference signal, the correlation function of two points apart a certain distance on the marker 4a is calculated from this reference signal and the output signals obtained at certain time intervals, and the one-direction deflecting amount and rotational deflecting amount are calculated using micro-spacing (h) of the points when the function maximizes, and from the calculating result, the max. deflecting amount of the hanging tool 3 is determined using a computing device.