An obstruction detection apparatus (44) is provided for use in closing a power driven vent, such as a window, that is located in an opening. The vent includes a first closing edge that moves as the vent is closed and the opening includes a second closing edge that is contacted by the first closing edge when the vent is in a fully closed position. The apparatus includes a detector (52) configured to detect an obstruction at points all along the second closing edge without requiring contact between the obstruction and the vent and to deliver a detection signal when an obstruction is detected. A controller (46) is connected to the detector for receiving the detection signal and delivering a corresponding alarm signal (48).
