Sheet inverter and method for inverting a sheet

1. A sheet inverter having two spaced apart sheet transport units and a rotation device, the rotation device supporting the sheet transport units in a rotatable manner about a common axis of rotation, the sheet transport units each comprising:

at least one transport element, which provides a direction of transport that extends parallel to the axis of rotation;

a controllable drive unit for driving the transport element; and wherein the rotation device is adapted to move the sheet transport units in an alternating manner between an input position and an output position, wherein the sheet transport unit in the input position is aligned with a transport unit arranged upstream to the sheet inverter and the sheet transport unit in the output position is aligned with a transport unit arranged downstream from the sheet inverted, wherein the axis of rotation extends centrally between the sheet transport units.

2. The sheet inverter according to claim 1 , wherein the sheet transport units each have a transport length which is equal to the maximum length of a sheet to be received.

3. The sheet inverter according to claim 1 , wherein the upstream transport unit is arranged on a first end of the sheet inverter and the downstream transport unit is arranged on the opposite end of the sheet inverter in the direction of transport.

4. The sheet inverter according to claim 1 , wherein the at least one transport element is at least one rotating transport belt having a flat transport section.

5. The sheet inverter according to claim 1 , wherein the at least one rotating transport belt is a suction belt and/or statically chargeable belt, and wherein a suction unit and/or a device for statically charging and discharging the transport belt is provided.

6. The sheet inverter according to claim 1 , wherein the sheet transport units each comprise two rotating transport belts which are synchronously drivable and which are also symmetrically arranged with respect to a longitudinal central plane of the sheet inverter.

7. The sheet inverter according to claim 1 , wherein the sheet transport units comprise at least one guide surface laterally adjacent to the transport elements, which guide surface is at the same level as the transport plane of the transport elements.

8. The sheet inverter according to claim 7 , wherein the sheet transport units each comprise at least one guide element, which is arranged opposite to the guide surface.

9. The sheet inverter according to claim 1 , comprising a control unit for controlling the drive speed of the feed transport unit.

10. A method for inverting sheets, in which at least one first sheet is received and transported in a direction of transport by a first sheet transport unit located in an input position, wherein the first sheet transport unit, while it has received the at least one first sheet, is rotated around an axis of rotation which extends parallel to the direction of transport into an output position, and wherein the at least one received sheet is transported and output in the direction of transport or in the opposite direction, wherein while the first sheet transport unit is rotated from the input position to the output position, a second sheet transport unit is rotated from the output position to the input position in order to receive at least one second sheet in said input position, while the first sheet transport unit outputs the at least one first sheet.

11. The method of claim 10 , wherein the transport speeds of the sheet transport units are individually controlled in the respective positions in accordance with a predetermined profile.

12. The method of claim 11 , wherein the transport speed when receiving the at least one sheet increases towards the end of the movement and when outputting the at least one sheet is initially higher than later.

13. The method according to claim 10 , wherein receiving and outputting the sheet occurs in the same direction.

14. A sheet inverter having two spaced apart sheet transport units and a rotation device, the rotation device supporting the sheet transport units in a rotatable manner about a common axis of rotation, the sheet transport units each comprising:

at least one transport element, which provides a direction of transport that extends parallel to the axis of rotation;

a controllable drive unit for driving the transport element; and wherein the rotation device is adapted to move the sheet transport units in an alternating manner between an input position and an output position, wherein the sheet transport unit in the input position is aligned with a transport unit arranged upstream to the sheet inverter and the sheet transport unit in the output position is aligned with a transport unit arranged downstream from the sheet inverted, wherein the drive units of the sheet transport units are independently controllable.

15. The sheet inverter according to claim 14 , wherein the sheet transport units each have a transport length which is equal to the maximum length of a sheet to be received.

16. The sheet inverter according to claim 14 , wherein the upstream transport unit is arranged on a first end of the sheet inverter and the downstream transport unit is arranged on the opposite end of the sheet inverter in the direction of transport.

17. The sheet inverter according to claim 14 , wherein the at least one transport element is at least one rotating transport belt having a flat transport section.

18. The sheet inverter according to claim 14 , wherein the at least one rotating transport belt is a suction belt and/or statically chargeable belt, and wherein a suction unit and/or a device for statically charging and discharging the transport belt is provided.

19. The sheet inverter according to claim 14 , wherein the sheet transport units each comprise two rotating transport belts which are synchronously drivable and which are also symmetrically arranged with respect to a longitudinal central plane of the sheet inverter.

20. The sheet inverter according to claim 14 , wherein the sheet transport units comprise at least one guide surface laterally adjacent to the transport elements, which guide surface is at the same level as the transport plane of the transport elements.