Patent ID: 7618040

Claim:
A gathering device for collating sheets, especially printed paper sheets, to form a sheet stack, comprising: a revolving body having an outer surface and being mounted to rotate about an axis, a drive unit for rotatably driving the revolving body, a feed device for feeding sheets to the revolving body at a feed rate, a device for generating a holding force to secure sheet stacks consisting of at least two sheets on the outer surface of the revolving body, said device for generating a holding force comprising an electrode arrangement having at least one electrode, and a voltage source connected to the electrode arrangement, said voltage source electrostatically charging an arriving sheet for generating a holding force fixing a sheet stack on the revolving body, a control mechanism which continuously detects the rotary position of the revolving body and which is able to alter the rotation of the revolving body so that an arriving sheet is secured flush with or at a predetermined distance from sheets already secured, a detection mechanism connected to the control mechanism for detecting the position of the sheets fed to the revolving body, said detection mechanism detecting a leading or trailing edge of a sheet to be received and/or a register mark arranged on the sheet and transmitting a corresponding signal to the control mechanism, wherein the control mechanism determines, in dependence on a first signal of the detection mechanism concerning a first arriving sheet and a second signal corresponding to the momentary rotary position of the revolving body, a NOMINAL rotary position of the revolving body, and further determines a correction value in dependence on a third signal of the detection mechanism concerning an additional arriving sheet, a substantially simultaneously detected second signal, and the previously determined NOMINAL rotary position, the control mechanism based on said correction value acting on the drive unit for the revolving body and/or the feed device in such a way that the revolving body takes up the NOMINAL rotary position when receiving the additional sheet.