A METHOD FOR DETERMINING A FULLY EXTENDED POSITION OF A SCREENING BODY OF A SCREENING DEVICE

摘要

A method for determining a fully extended position of a screening body (14) of a screening device (12) for a roof window. The screening device (12) comprises a control unit comprising a data storage device, an electric motor (18) comprising a tachometer (181), a roller tube (15), a screening body (14) and a first and a second spring element (164, 174). The method comprises the steps of driving the screening body (14) from a fully retracted position to a fully extended position, in which the spring elements (164, 174) are tensioned to a first tension level, T 1 , stopping the electric motor (18) at a point at which the spring elements (164, 174) are tensioned to a second tension level, T 2 , above the first tension level, T 1 , measuring the number of revolutions, R d , of the roller tube (15) necessary to drive the screening body (14) to the said position at which the motor (18) is stopped, storing the measured number of revolutions, R d , in the data storage device, measuring the number of revolutions, R b , of the roller tube, that a release of a tension corresponding to the difference, ”T, between the first tension level, T 1 , and the second tension level, T 2 , will cause the roller tube (15) to move back towards the fully retracted position, storing the number of revolutions, R b , in the data storage device, and calculating and storing in the data storage device a value R = R d - R b .