Inking device and corresponding adjustment method

Abstract

An inking device of a printing unit includes an ink reservoir, an ink film pick-up roller which has a shaft, and an inking roller having a shaft.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from a reading of the following description, given purely by way of example and with reference to the appended drawings, in which:

FIG. 1 is a schematic side view of a printing unit according to the present invention;

FIG. 2 is a perspective view of a portion of an inking device according to the present invention;

FIG. 3A is a schematic top view of an inking device according to a first embodiment of the present invention;

FIG. 3B is a schematic top view of an inking device according to a second embodiment of the present invention;

FIGS. 4A to 4C are charts illustrating parameters when inking devices according to the present invention are used.

Claims

1. An Inking device of a printing unit comprising: a reservoir of ink,an ink film pick-up roller having a first shaft,an inking roller defining a printing width and being capable of transferring ink from the ink reservoir to the ink film pick-up roller, the inking roller having a second shaft, anda detector capable of evaluating the actual distance between the inking roller and the ink film pick-up roller within the printing width and/or of detecting an angular displacement of the first and second shafts relative to each other and providing an output signal representing the angular displacement.

2. The inking device as recited in claim 1 further comprising a controller capable of angularly displacing the second shaft relative to the first shaft, and the controller being capable of reducing the angular displacement as a function of the output signal.

3. The inking device as recited in claim 1 further comprising a controller capable of positioning the ink film pick-up roller relative to the inking roller as a function of the output signal.

4. The inking device as recited in claim 1 wherein the detector includes at least one sensor capable of indicating a density of the ink printed on a medium to be printed in at least two different locations over the printing width.

5. The inking device as recited in claim 1 further comprising at least two screws for adjusting a thickness of the ink on the inking roller.

6. The inking device as recited in claim 5 wherein the detector is capable of detecting the position of the adjustment screws.

7. The inking device as recited in claim 6 wherein the detector is capable of detecting the position of at least one of the adjustment screws corresponding to a lithographic offset value.

8. The inking device as recited in claim 7 includes a memory storing a value which represents a lithographic offset position when the shafts of the inking roller and pick-up roller are parallel.

9. The inking device as recited in claim 1 wherein the controller includes a first motor and a first transmission capable of transmitting a driving action of the first motor into an angular displacement of the first shaft relative to the second shaft.

10. The inking device as recited in claim 9 wherein the controller includes a second motor and a second transmission capable of transmitting a driving action of the second motor into an angular displacement of the first shaft relative to the second shaft.

11. The inking device as recited in claim 9 wherein the first transmission is capable of displacing one end of the pick-up roller radially relative to the second shaft.

12. The inking device as recited in claim 1 wherein the controller includes a manual controller.

13. The inking device as recited in claim 12 wherein the manual controller includes a micrometer screw

14. A method for adjusting the inking device as recited in claim 1 comprising the following steps: determining the actual distance between the ink film pick-up roller and inking roller at least at two points of the printing width and/or determining the actual angular displacement of the first shaft and second shaft relative to each other; anddisplacing the first shaft relative to the second shaft by reducing the actual angular displacement and/or by modifying the relative radial position of the first shaft relative to the second shaft.

15. The method as recited in claim 14, further comprising: verifying whether the actual angular displacement is greater than a threshold displacement and/or verifying whether the actual distance is greater than a threshold distance; andimplementing the displacing step only when the actual angular displacement is greater than the threshold displacement and/or when the actual distance is greater than the threshold distance.

16. The method as recited in claim 14 the following steps: after the displacing step, determining a lithographic offset value of at least one adjustment screw; andstoring the lithographic offset value determined in this manner in a memory.