Method and a system for the extrapolation of densitometric measured values in not measured wavelength ranges at a printing press

Method for controlling the composition of an ink mixture (11, 31) for at least one printing press (2)

• in which actual optical values (I) of light (7) are obtained, whereas the light has interacted at least with parts of the printing picture (9), which is generated by the printing press (2) on the printing substrate (6) using an ink mixture which is provided by an ink supply system (61)
• in which, due to the deviation of the actual optical value (I) from optical reference values (S), a corrective ink mixture (31) is created, which is added to the ink mixture which is provided by the ink supply system (61) and which changes the ratio of the amounts of ink pigments therein,
• and in which first actual optical values (I) are obtained inline, that is at running and just printed printing substrate (6), wherein these actual optical values (I) are densitometrical values,
• characterized in
• that estimated values with respect to the light intensities (L) in second selected wave length ranges (52) which differ from the first wave length intervals (51) and in which the light intensity (L) is not measured are deduced from the densitometric measured values (51),
• that the method for controlling the composition of an ink mixture (11, 31) for at least one printing press (2) works with the aid of a central and a decentral ink mixing device (16, 24)
• and that the control device (3) passes data about the composition of the ink mixture (21, 31) to the decentral ink mixing device (16, 24).

System (1) for controlling the composition of an ink mixture (11, 31) for at least one printing press (2),

• in which (1) actual optical values (I) of light (7) are determinable with the aid of an optical measurement device (4) and
• in which due to the deviation of the actual optical values (I) from the optical reference value (S) at least one corrective ink mixture (31) is creatable, which can be added to the ink mixture contained in the ink supply system (61) of the printing press (2), so that there the ratio of the quantities of the ink pigments can be changed
• that the first actual optical values (I) can be obtained inline, that is at running and just printed printing substrate (6),
• wherein these actual optical values (I) are densitometrical values,
• characterized in
• that estimated values with respect to the light intensities (L) in second selected wave length intervals (52), which differ from the first wave length intervals (51) and in which the light intensity (L) is not measurable by the first optical measuring device (4), can be deduced from the densitometric measured values (51),
• that the system comprises a central and a decentral ink mixing device (16,24),
• and that the control device (3) is provided with interfaces (29), which permit the control device (3) to pass data about the composition of the ink mixture (21, 31) to the decentral ink mixing device (16, 24).

Printing press (2), comprising

• at least one ink supply system (61), with which ink can be transferred from an inlet point (10) to the printing substrate,
• at least one optical measuring device (5, 8) for measuring actual optical values (I) of light, in which the actual optical values (I) are from light of selected wavelength ranges (51, 53) and in which the light has interacted with at least parts of the printing picture,
• characterized in that
• the printing press (2) further comprises
• an ink mass determination device (12) for determining the weight of at least parts of the ink which is located within an ink supply system
• a control and evaluation device (3) which can be provided with measured values (I) from the optical measuring device (12)
• and with measured values from the ink mass determination device and which can be used to determine the optical deviation (ΔK), that is the deviation of the actual optical values (I) from the optical reference values (S), which are available as light intensity values (L) of selected wavelength ranges,
• and which control and evaluation device (3) can be used to determine on the basis of the optical deviation (ΔK) and the values from the weighing devices (12), how much corrective ink having a determined composition is fed to the printing press (2) in order to approximate the actual optical values (I) to the optical reference values (S).

Method for the operation of a printing press (2), comprising the steps of:

• transferring ink from an inlet point (10) to the printing substrate (6) via at least one ink supply system (61)
• measuring actual optical values (I) of light by at least one optical measuring device (4, 54) wherein said actual optical values (I) are intensity values of light in selected wavelength range (51, 52)
• and wherein the light has undergone an interaction with at least parts of the print image (9)
• characterized in that
• the method further comprises the steps of:
• measuring and/or estimating the mass of the ink contained in said at least
• one ink supply system (61) by using an ink mass determination device (12)
• feeding the values from the optical measuring device (4, 54) and from the
• ink mass determination device (12) to a control and evaluation device (3),
• determining the optical deviation (ΔK), that is the deviation of the actual optical values (I) from the optical reference values (S), which are also available as light intensity values (L) of selected wavelength ranges (51, 53), by said control and evaluation device (3) and
• determination on the basis of the optical deviation and the values from the weighing devices (12), how much corrective ink having a determined composition is fed to the printing press (2) in order to approximate the actual optical values (I) to the optical reference values (S) by said control and computing device.

Method according to the preceding claim, wherein

• at least two measured values (50) are taken into account and
• wherein said at least two measured values (50) reflect at least one former (ΔK1) and one later (ΔK2) deviation,
• both (ΔK1, ΔK2) having occurred at an adjustment of the reference value (S) of a printing ink (11) during a former printing job, when is was printed with a former ink mixture and with a later ink mixture,
• wherein said later ink mixture was corrected in comparison with the former ink mixture.

Method for controlling the composition of an ink mixture (11, 31) for at least one printing press (2),

• in which actual optical values (I) of light (7) are obtained, whereas the light (7) has interacted at least with parts of the printing picture (9), which is generated by the printing press (2) on the printing substrate (6) using an ink mixture which is provided by an ink supply system (61)
• and in which, due to the deviation of the actual optical value from optical reference values (S), a corrective ink mixture (31) is created, which is added to the ink mixture (11) which is provided by said ink supply system (61) and which changes the ratio of the amounts of ink pigments therein,
• characterized in that
• the ink mixtures (11, 31) used in the method are provided by different ink mixing devices (16, 24).

System (1) for controlling the composition of a ink mixture for at least one printing press (2),

• which (1) comprises at least one optical measuring device, which can record actual optical values (1) of light, whereby the recordable light has interacted at least with parts of the printing picture (9), that is creatable on a printing substrate by at least one printing press (2) using an ink mixture which is provided by an ink supply system (61) of said printing press (2), and
• which comprises components, with which a corrective ink mixture (31) is creatable on the basis of deviation of the actual optical values (I) from optical reference values (S), whereas said corrective ink mixture (31) can be added to the ink mixture (11) which is provided by the ink supply system (61) in order to change the ratio of the amounts of ink pigments therein (61)
• characterized in that
• the system comprises at least two different ink mixing devices (16, 24), each usable to supply ink mixtures (11, 31).