Patent ID: 7712735

Claim:
An unstacker device for unstacking flat objects, which device comprises a motor-driven feed magazine controlled so as to move flat objects in a stack and on edge facing an unstacking head provided with a motor-driven drive having a perforated belt and a suction chamber, which motor-driven unstacking head drive is actuated so as to separate a current first object from the stack and so as to eject it in a direction that is transverse to the direction in which the stack of flat objects is moved, in which device the motor-driven unstacking head drive is actuated and stopped each time a current object is unstacked, and the stack of flat objects is straightened up in the magazine in response to detection of signals delivered by a plurality of sensors disposed in the unstacking head, a first sensor being disposed to detect presence of a bottom portion of the current object facing the unstacking head, a second sensor being disposed to detect presence of a first intermediate portion of the current object facing the unstacking head, said first intermediate portion being situated above said bottom portion of the current object, wherein a third sensor is disposed to detect presence of a second intermediate portion of the current object facing the unstacking head, said second intermediate portion being situated above said first intermediate portion of the current object, said sensors being disposed in the unstacking head in a manner such as to deliver signals indicating that said current object is presented appropriately relative to the unstacking head, wherein said unstacker device further comprises a control unit connected with said sensors, said control unit being programmed for actuating the drive of the unstacking head so as to separate a current first object from the stack if the signals indicate that the current object is presented appropriately and for stopping the drive of the unstacking head if the signals indicate that the current object is presented inappropriately.