Quality control device

1. A device for quality control of an imprinted sheet comprising:

a movable gripper adapted to pull a sheet in a sheet conveying direction at a first speed;

a CCD camera;

a belt supported for movement in said sheet conveying direction at a second speed;

a motor for driving said belt;

a drive motor control for regulating said motor to move said belt so that said second speed is not greater than said first speed; and

means for sensing a pulling force exerted by said movable gripper on the sheet, said drive motor control regulating said second speed of said belt to not exceed a threshold value of said pulling force.

2. The device of claim 1 further including a suction box having a suction surface and wherein said belt is movable over said suction surface.

3. The device of claim 2 wherein said belt is an endless belt and further including first and second guide rollers spaced about said suction box and supporting said belt looped around said suction box.

4. The device of claim 1 wherein said CCD camera is a planar camera.

5. The device of claim 1 further including a conveyor chain, said gripper being guided by said conveyor chain, said belt being driven by said conveyor chain.

6. The device of claim 5 further including a chain wheel, said chain wheel being in engagement with said conveyor chain, at least one guide roller for said belt, and a drive mechanism between said chain wheel and said at least one guide roller.

7. The device of claim 6 wherein said chain wheel has a pitch circle diameter, said drive mechanism has a transmission and said at least one guide roller has an exterior diameter, said pitch circle diameter, said transmission ratio, said belt thickness and said exterior diameter being selected such that a speed of said belt is no greater than a track speed of said gripper.

8. The device of claim 1 further including carriers on said belt, and wherein said gripper includes a track, said carriers being in engagement with said track of said gripper.

9. The device of claim 1 wherein said sheet conveying direction is vertical.

10. The device of claim 1 further including a sheet feeder and a printing group of a sheet-fed rotary printing press and wherein said device is located between said printing group and said sheet feeder.

11. A device for quality control of an imprinted sheet comprising:

a movable gripper having a first speed and adapted to pull a sheet in a sheet conveying direction;

a CCD camera; and

a belt supported for movement at a second speed no greater than said first speed in said sheet conveying direction, said sheet conveying direction being vertical.

12. The device of claim 11 further including a suction box having a suction surface and wherein said belt is movable over said suction surface.

13. The device of claim 12 wherein said belt is an endless belt and further including first and second guide rollers spaced about said suction box and supporting said belt looped around said suction box.

14. The device of claim 11 wherein said CCD camera is a planar camera.

15. The device of claim 11 further including a drive motor for said belt.

16. The device of claim 15 further including a drive motor control device adapted to regulate said motor to drive said belt at a first speed and further wherein said gripper has a second speed, said first speed being no greater than said second speed.

17. The device of claim 16 further wherein said gripper exerts a pulling force on a sheet and wherein said drive motor control device regulates said belt speed whereby a threshold of said pulling force is not exceeded.

18. The device of claim 11 further including a sheet feeder and a printing group of a sheet-fed rotary printing press and wherein said device is located between said printing group and said sheet feeder.

19. A device for quality control of an imprinted sheet comprising:

a movable gripper adapted to pull a sheet conveying direction;

a CCD camera;

a belt supported for movement in said sheet conveying direction, said sheet conveying direction being vertical; and

carriers on said belt, said gripper including a track, said carriers being in engagement with said track of said gripper.

20. The device of claim 19 further including a suction box having a suction surface and wherein said belt is movable over said suction surface.

21. The device of claim 20 wherein said belt is an endless belt and further including first and second guide rollers spaced about said suction box and supporting said belt looped around said suction box.

22. The device of claim 19 wherein said CCD camera is a planar camera.

23. The device of claim 19 further including a drive motor for said belt.

24. The device of claim 23 further including a drive motor control device adapted to regulate said motor to drive said belt at a first speed and further wherein said gripper has a second speed, said first speed being no greater than said second speed.

25. The device of claim 24 further wherein said gripper exerts a pulling force on a sheet and wherein said drive motor control device regulates said belt speed whereby a threshold of said pulling force is not exceeded.

26. The device of claim 19 further including a sheet feeder and a printing group of a sheet-fed rotary printing press and wherein said device is located between said printing group and said sheet feeder.

27. A device for quality control of an imprinted sheet comprising:

a movable gripper adapted to pull a sheet in a sheet conveying direction;

a track for said movable gripper;

a CCD camera;

a belt supported for movement in said sheet conveying direction;

a drive motor for said belt; and

carriers on said belt, said carriers engaging said track of said grippers.