| 摘要 |
<p>A rotor assembly for counting sheets in a stack has a support (18) on which is rotatably mounted a rotor (22) such that the rotor engages an edge region of the stack. The rotor has a plurality of helical transfer grooves (45) through which sheets are transferred one at a time from one side of the rotor to the other. A foot (21) bears on the rotor (12) and has a port which, as the rotor rotates, comes into and out of communication with further ports on the rotor each leading to a respective groove (45), whereby air is drawn in a timed relationship through the rotor to assist the transfer of sheets through the helical grooves (45). The rotor (12) is movable axially with respect to its support (18) and there is a detector arranged to detect the position of the foot (21) with respect to the support (18) thereby to give an output (31) indicative of the position of the rotor (12) with respect to the support (18).</p> |
