Ink key control in a printing press including lateral ink spread, ink saturation, and back-flow compensation

A method for determining initial ink key control settings for a plurality of ink keys in a printing press wherein each of the plurality of ink keys controls the amount of ink supplied to a roller and then to a respective ink key zone on a substrate to print an image, the method comprising:

• determining a press model that relates image requirements to ink key control settings, the press model including a gain and a respective offset associated with each ink key;
• using the press model to calculate initial ink key control settings for a first print job using an initial gain and a respective initial offset for each ink key;
• obtaining final ink key control settings for each ink key after the first print job is satisfactorily completed;
• calculating an updated gain by multiplying the initial gain with a summation over a plurality of ink keys of the difference between the final ink key control setting and the respective initial offset and then dividing by the summation over the plurality of ink keys of the difference between the initial ink key control setting and the respective initial offset;
• using the press model to calculate an adjusted ink key control setting using the updated gain;
• calculating an updated offset for each respective ink key by obtaining the difference between the adjusted ink key control setting and the final ink key control setting and adding the initial offset;
• and
• using the press model to calculate initial ink key control settings for a second print job using the updated gain and the respective updated offsets for each ink key.

A method for determining initial ink key control settings for a plurality of ink keys in a printing press wherein each of the plurality of ink keys controls the amount of ink supplied to a roller and then to a respective ink key zone on a substrate to print an image, the method comprising:

• determining a press model that relates image requirements to ink key control settings, the press model including a gain, a ratchet setting, and a respective offset associated with each ink key;
• using the press model to calculate initial ink key control settings for a first print job using an initial gain, an initial ratchet setting and an initial respective offset for each ink key;
• obtaining a final ratchet setting and final ink key control settings for each ink key after the first print job is satisfactorily completed;
• using the press model to calculate re-scaled ink key control settings using the final ratchet setting;
• calculating an updated gain by multiplying the initial gain with a summation over a plurality of ink keys of the difference between the final ink key control setting and the respective initial offset and then dividing by the summation over the plurality of ink keys of the difference between the re-scaled ink key control setting and the respective initial offset;
• using the press model to calculate an adjusted ink key control setting using the updated gain and final ratchet setting;
• calculating an updated offset for each respective ink key by obtaining the difference between the adjusted ink key control setting and the final ink key control setting and adding the initial offset;
• and
• using the press model to calculate initial ink key control settings for a second print job using the updated gain and the respective updated offsets for each ink key.