Patent ID: 8037922

Claim:
A device for operating a movable closure in travel between limit positions, the device including an apparatus for monitoring motion of the movable closure between said limit positions, the apparatus comprising: an absolute position encoder for identifying whether the closure is in one of a plurality of sectors of travel between the limit positions, the absolute position encoder arranged for rotation with the movable closure; a relative position encoder for monitoring the speed and relative position of the closure, the relative position encoder arranged to convert rotational motion into a sequence of pulses; and an encoder drive for operatively coupling the relative position encoder and the absolute position encoder to the closure, such that during operation there is a fixed relationship between motion of the closure and movement of both encoders; wherein the absolute position encoder includes an adjustment assembly comprising a first element arranged always to rotate with the absolute position encoder and a second element arranged always to rotate with the relative position encoder, the first element being selectively adjustable in rotational position relative to the second element to allow adjustment of the position of the absolute position encoder without movement of the encoder drive or the relative position encoder; and wherein the device further comprises a gear assembly for transferring drive torque to the movable closure and the adjustment assembly does not form part of the gear assembly.