METHOD AND APPARATUS FOR DETECTING OBSTACLES FOR ELECTRIC SHUTTER

摘要

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting obstacles for an electric shutter by detecting the electric current value or the rotational frequency of a mortar provided in the electric shutter. SOLUTION: In a method of detecting obstacles in an electric shutter, the electric current value or the rotational frequency of mortar 4b in the winding-up process of a shutter body 1 from the lowest winding point Sb to the highest winding point Sa and also the winding-down process from highest winding point Sa to the lowest winding point Sb are respectively measured in advance in condition that there are no obstacles both in the shutter body 1 and a winding drum 2. A winding-up control value and a winding-down control value are determined in accordance with the measured values. The apparatus recognizes the existence of obstacles in case that the measured value of the electric current value or the rotational frequency of mortar 4b in a practical operation surpasses the predetermined winding-up control value or the winding-down control value.