Inking system with embedded colour correction
AssigneeBobst Firenze S.R.L.
InventorFederico D'Annunzio
Life of this patent
Estimating the term…
Abstract
The present invention concerns an inking for a flexographic or a rotogravure press. The inking system uses a very small amount of ink coupled with an ink source made of two tanks with two different inks. Thanks to feedback given by measuring the output directly on the printed support, the system mixes the ink in the optimal proportions to ensure an optimal printing quality at any time. It can compensate any effect due to environmental changes like the humidity or the temperature. This system, coupled with a seven colours press allows for the replacement of spot colours in most cases thereby saving times and costs.
Claims20
An inking system for a rotary printing unit and for the adjustment of printing parameters, the rotary printing unit being configured to print on a printing support, the inking system comprising:
- an inking cylinder and an etched cylinder arranged to retain ink between them in a nip area and configured to turn in a same direction;
- a doctor blade having a lowest end positioned on the etched cylinder above ink in the nip area to remove excess ink from a top surface of the etched cylinder;
- an ink source comprising two tanks for storing ink and suitable for drawing ink from the two tanks in configurable amounts;
- a sensor configured to obtain a measured value of the printing parameters on the printing support;
- control means adapted to compare the measured value of the printing parameters with a target value;
- wherein the ink source is configured to be operatively connected to the control means whereby, when the measured value of the printing parameters differs from the target value, the ink source is activated by the control means to provide ink from the two tanks in corrected relative amounts to the nip area.
A method for supplying ink for an inking system for a rotary printing unit configured to print on a printing support, the inking system including an inking cylinder and an etched cylinder arranged to retain ink between them in a nip area, the method comprising:
- rotating the inking cylinder and the etched cylinder in a same rotational direction;
- measuring at least one printing characteristic on the printing support at the output of the printing unit using a sensor;
- and
- when the measured at least one printing characteristic does not match a target predefined value,
- computing a corrected mixture of ink and drawing the corrected mixture from an ink source, and
- delivering said corrected mixture to the nip area between the etched cylinder and the inking cylinder.
An inking system for a rotary printing unit and for adjustment of printing parameters, the rotary printing unit being configured to print on a printing support, the inking system comprising:
- an inking cylinder and an etched cylinder arranged to retain ink in a nip area, the nip area being defined as a volume between the inking cylinder and the etched cylinder in a vicinity of a contact point of the inking cylinder and the etched cylinder, the inking cylinder and the etched cylinder turning in a same rotation direction;
- an ink source comprising two tanks for storing ink and suitable for drawing ink from the two tanks in configurable amounts;
- a sensor configured to obtain a measured value of the printing parameters on the printing support;
- and
- a control system configured to:
- compare the measured value of the printing parameters with a target value;
- determine a volume of ink present in the nip area based on a printing speed;
- and
- when the measured value of the printing parameters differs from the target value, control the ink source to provide ink from the two tanks in corrected relative amounts directly to the volume of ink in the nip area between the inking cylinder and the etched cylinder, wherein the corrected relative amounts of ink are based on the determined volume based on the printing speed.
Dependencies are inferred from the claim text.