U.S. patent application number 12/734971 was filed with the patent office on 2011-02-24 for colour-management.
Invention is credited to Andreas Ihme.
Application Number | 20110041712 12/734971 |
Document ID | / |
Family ID | 39745530 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110041712 |
Kind Code |
A1 |
Ihme; Andreas |
February 24, 2011 |
COLOUR-MANAGEMENT
Abstract
The invention presents a 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, 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, 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 and which changes the
ratio of the amounts of ink pigments therein. The ink mixtures (11,
31) used in the method are provided by different ink mixing devices
(16, 24).
Inventors: |
Ihme; Andreas; (Lengerich,
DE) |
Correspondence
Address: |
JACOBSON HOLMAN PLLC
400 SEVENTH STREET N.W., SUITE 600
WASHINGTON
DC
20004
US
|
Family ID: |
39745530 |
Appl. No.: |
12/734971 |
Filed: |
February 8, 2008 |
PCT Filed: |
February 8, 2008 |
PCT NO: |
PCT/EP2008/000992 |
371 Date: |
June 7, 2010 |
Current U.S.
Class: |
101/171 ;
101/211 |
Current CPC
Class: |
B41F 31/005 20130101;
B01F 13/1072 20130101; B01F 13/1055 20130101; B41F 33/0045
20130101 |
Class at
Publication: |
101/171 ;
101/211 |
International
Class: |
B41M 1/14 20060101
B41M001/14 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 6, 2007 |
DE |
10 2007 059 175.8 |
Dec 6, 2007 |
DE |
10 2007 059 176.6 |
Dec 6, 2007 |
DE |
10 2007 059 177.4 |
Claims
1. 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, 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 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 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).
2. Method according to the preceding claim wherein the first ink
mixing device (16) is an ink kitchen (16), which is used for the
supply of ink (11) for a first number (N) of printing presses (2),
the second ink mixing device (24) is a decentralized mixing device
(24), which is used for the supply of ink (11) for a second number
(M) of printing presses (2), and the first number (N) of printing
presses is greater than or equal to the second number (M) of
printing presses (2).
3. Process according to the preceding claim, wherein the second
decentralized mixing device, which is used for the supply of ink
for the second number (M) of printing presses, is assigned to a
single printing press.
4. Process according to claim 1, wherein the composition of the ink
mixture is controlled or closed loop controlled at least two
printing presses (2) and at least one of the ink mixing devices is
moved between at least two printing presses for providing these
printing presses with ink mixtures.
5. Process according to the preceding claim, wherein the ink mixing
device, which is moved between at least two printing presses (2)
for providing these printing presses with ink mixtures, feeds
different ink components to an ink supply system (61) of a colour
deck (8) of the printing press (2) and wherein these ink components
mix up only within said ink supply system (61).
6. Process according to claim 1, wherein at least one of the
measurements, with which actual optical values (I) are obtained, is
a densitometrical measurement, that takes measurements of the light
intensity (L) only inside first selected wavelength ranges (51)
which are part of the transparent parts (TB) of the respective ink
mixture.
7. Process according to claim 1, wherein estimated values with
respect to the light intensities (L) in second selected wave length
ranges (53) which differ from the first wavelength ranges (51) and
in which the light intensity is not measured are deduced or
extrapolated from the densitometric measurement.
8. Process according to the preceding claim, wherein for said
estimation the optical values (50) are taken into account, which
have been the result of prior measurement of light that interacted
with the used ink (11) or the used ink components.
9. Process according to claim 7, wherein for said estimation at
least parts of a curve (50) are taken into account, whereas the
curve (50) reflects the spectral intensity (L) of the remitted
light (7), that is the result of the interaction of light with the
used ink (11) or with the used ink components in a wave length
range.
10. Process according to claim 7, wherein the densitometric
measured values underlie the production of a correction mixture
(31).
11. Process according to claim 7, wherein at least one of the
measurements to obtain actual optical values (I) is a
spectral-photometrical measurement that comprises measurement of
light intensities (L) in all wavelength ranges (51, 52) of the part
of the transparent part of the respective ink mixture.
12. Process according to the preceding claim, wherein the
spectrophotometric measured values are the basis for the production
of basic mixtures (21).
13. Process according to claim 11, wherein the spectrophotometric
measured values are taken as a basis for re-checking the quality of
the densitometrical measurement and/or of said estimation.
14. Process according to claim 1 wherein for the supply of said
correction mixture (31) less different kinds of basic inks (26) are
used than for the production of the basic ink mixture (21).
15. Process according to claim 1 wherein at least at one of the
following devices measurements of the mass of the ink and/or the
volume of the ink are performed and wherein said measurements are
taken into account at the creation of the ink mixture: at ink
containers (18) of the centralized ink kitchen (16) at ink
repositories (10) of at least one printing press (2) at ink
repositories (25) of the decentralized mixing device.
16. Mixing device for supplying of ink mixtures for at least one
printing press (2), comprising at least two ink repositories and a
dosing device, characterized in that the mixing device further
comprises means for movement--preferentially wheels.
17. Mixing device according to the preceding claim, wherein a
control and evaluation device (23) is provided.
18. Mixing device (24) according to the preceding claim, wherein at
least a part of said dosing device (13, 38, 28) of the mixing
device is controllable by said control and evaluation device.
19. Mixing device (24) according to the preceding claim, further
comprising interfaces (30) to external control components (3, 19),
which can be used to submit data relating to the ink mixtures (11,
31) which are needed by the at least one printing press (2).
20. System (1) for controlling the composition of a ink mixture for
at least one printing press (2), which 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 of said printing
press, and which comprises components, with which a corrective ink
mixture is creatable on the basis of deviation of the actual
optical values (I) from optical reference values (S), whereas said
corrective ink mixture can be added to the ink mixture 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).
21. 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 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 from the optical
measuring device and with measured values from the ink mass
determination device and which can be used to determine the optical
deviation that is the deviation of the actual optical values from
the optical reference values (S), which are available a light
intensity values (L) of selected wavelength ranges, and which
control and evaluation device can be used to determine 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).
22. Printing press (2) according to the preceding claim, wherein a
device for measuring the viscosity of the ink contained in the ink
supply system is provided.
23. Printing press (2) according to the preceding claim, wherein a
connection line for the transfer of measured values from said
device for measuring the viscosity to the control and evaluation
device (3) is provided.
24. Printing press (2) according to claim 1, wherein with the
control and evaluation device (3) the composition of the ink
contained in said ink supply system after at least one ink
correction process is computable on the basis of the values from
said ink mass determination device and preferably from the device
for measuring the viscosity of the ink as well as on the basis of
the quantity and the composition of the corrective ink.
25. Printing press (2) according to the preceding claim, wherein a
memory device for recording the composition of the ink after at
least one in correction process is provided.
26. Printing press (2) according to claim 1, wherein with the
control and evaluation device (3) the mass of the ink is estimated,
which ink is contained in at least a part of that parts of said ink
supply system, which is not available for measuring the mass of the
ink by the ink mass determination device.
27. Printing press (2) according to the preceding claim, wherein
the volume of at least a part of ink supply system (61), in which
no measurement of the mass of the ink by the ink mass determination
device is possible, is known by the control and evaluation device
and wherein said control and evaluation device performs said
estimation on the basis of said volume.
28. Printing press (2) according to claim 1, wherein an optical
measuring device is provided for recording densitometrial
measurements, which base on the measurement of the light intensity
(L) in first selected wavelength ranges (51).
29. Printing press (2) according to the preceding claim, wherein
with the control and evaluation device (3) estimated values with
respect to the light intensities (L) in second selected wavelength
ranges (52) which differ from the first wavelength ranges (51) and
in which the light intensity is not measured are deduced from the
densitometric measurement (51).
30. Printing press (2) according to the preceding claim, wherein
optical values (50) are known by the control and evaluation device
(3), wherein said values (50) result from an interaction of light
with the used ink of the used ink components and wherein these
values can be taken into account for said estimation.
31. Printing press (2) according to claim 29, wherein estimated
values are considered by the control and computing device in order
to compute the mass and the composition of the corrective ink.
32. Printing press (2) according to claim 29, wherein the optical
values, which can be taken into account by the control and
evaluation device, comprising at least parts of a curve (50) which
reflects the spectral intensity (L) of the remitted light (7) that
is the result of the interaction of light with the printed colour
or with the printed colour components in a wavelength range.
33. Printing press (2) according to claim 1, wherein a memory
device is provided which is adjusted to save optical measured
values (50) and/or ink formulas and/or ink compositions and a
control and evaluation device (3) is provided which is adjusted to
take into account said saved values during the execution of a later
printing job.
34. 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 wherein said actual optical values (I) are
intensity values of light in selected wavelength range and wherein
the light has undergone an interaction with at least parts of the
print image 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 by using an ink mass
determination device feeding the values from the optical measuring
device (4, 54) and from the ink mass determination device to a
control and evaluation device (3), determining the optical
deviation .DELTA.K, 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, 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.
35. Method according to the preceding claim, wherein different
printing jobs are performed sequentially with said printing press
(2), wherein an equal optical reference value (S) with regard to at
least one colour underlies at least at two of said different
printing jobs for at least one colour and wherein measured values
(50) and/or ink formulas of a former of said at least two different
printing jobs are taken into account for supplying of the ink
mixture for a later one of the at least two printing jobs.
36. Method according to the preceding claim, wherein for supplying
of said ink mixture for a later of the at least two printing jobs
measured values (50) are taken into account and wherein one of
these measured values (50) is the deviation (.DELTA.K), which has
resulted from the former of the at least two different printing
job, when it was printed with an ink mixture, which was used for
the attainment of the optical reference value (S).
37. 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 reflect at least one former
(.DELTA.K.sub.1) and one later (.DELTA.K.sub.2) deviation, both
(.DELTA.K.sub.1, .DELTA.K.sub.2) 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.
38. Method according to claim 1, wherein the deviations (.DELTA.K,
.DELTA.K.sub.1, .DELTA.K.sub.2) and the optical reference value (S)
are determined in coordinates of a colour space, wherein a
difference chromaticity coordinate (D) is determined by subtract
the deviation from the reference chromaticity coordinate (S) in a
vectorial manner and wherein a resulting ink formula is computed by
the control and computing device on the basis of the difference
chromaticity coordinate (D).
39. Method according to claim 1, wherein in addition to the optical
measured values (50) the composition and/or formulas of the ink
mixtures, which led to the deviations (.DELTA.K, .DELTA.K.sub.1,
.DELTA.K.sub.2) of said optical measured values (I) from the
optical reference values (S), are taken into account.
40. Method for controlling the composition of an ink mixture (11,
31) for at least one printing press (2), in which actual optical
value (I) of light are obtained, whereat the light has interacted
at least with parts of the printing picture, which is generated by
the printing press on the printing substrate using an ink mixture
which is provided by an ink supply system and in which, due to the
deviation of the actual optical value (I) from optical reference
values (S), a corrective ink mixture is created, which is added to
the ink mixture which is provided by the ink supply system and
which changes the ratio of the amounts of ink pigments therein,
characterized in that first actual optical values are obtained
inline, that is at running and just printed printing substrate,
wherein these actual optical values are densitometrical values.
41. Method according to the preceding claim, 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 is not
measured are deduced from the densitometric measured values
(51).
42. Method according to the preceding claim, wherein for said
estimation the optical values are taken into account, which have
been the result of prior measurement of light that interacted with
the used ink or the used ink components.
43. Method according to claim 41, wherein for said estimation at
least parts of a curve (50) are taken into account, whereas the
curve (50) reflects the spectral intensity (L) of the remitted
light (7), that is the result of the interaction of light with the
used ink or with the used ink components in a wavelength range.
44. Method according to claim 41, wherein also second actual
optical values are obtained by a spectrophotometrical measurement,
whereat the spectrophotometrical measurement bases on measured
value of the light intensity (L) in all wavelength ranges (51, 52)
of the part of transparent part of the respective ink mixture.
45. Method according to the preceding claim, wherein the
spectrophotometric measurements underlie the generation of basic
mixtures (21).
46. Method according to claim 44, wherein the spectrophotometric
measurement are taken as a basis for re-checking the quality of the
densitometrical measurement and/or of said estimation.
47. Method according to claim 1, wherein the second actual
spectrophotometrical measured value is acquired offline, that means
at the printing substrate, which is located outside the printing
process.
48. System (1) for controlling the composition of a ink mixture 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 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 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 characterized in that the first actual
optical values (I) can be obtained inline, that is at running and
just printed printing substrate, wherein these actual optical
values (I) are densitometrical values.
49. System (1) according to the preceding claim, wherein 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 is not measured,
can be deduced from the densitometric measured values (51).
50. System according to claim 1, wherein the control device (3) of
the at least one printing press (2) is adjusted so that it
determines the composition of a corrective ink mixture and the
basis of the actual optical values (I)
51. System according to the preceding claim, wherein the control
device (3) of said printing press is adjusted for the determination
of the corrective ink mixture and wherein at least one ink mixing
device (16, 24) is provided, which, on its part, is equipped with a
control device (19, 23), that is adjusted for the determination of
the basic ink mixture.
52. System according to the preceding claim, wherein the at least
one ink mixing device (16, 24) is the central ink mixing device
(16).
53. System according to claim 1, wherein 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 to a central
and/or decentral ink mixing device (16, 24).
54. System, device or machine according to claim 1 which refer to a
system, device or machine.
55. Method or process according to claim 1 which refer to a method
or a process.
Description
[0001] The invention relates to a method for the control of the
chemical composition of a colour mixture at least one printing
press, a mixing device for an ink mixture as well as a system for
the control of the chemical composition of the ink mixture at least
one printing press as well as an apparatus and a method for the
determination of the ink mass and the viscosity at a printing press
for colour control as well as a method and a system for the
extrapolation of densitometric measured values in not measured
wavelength ranges at a printing press.
[0002] In printing presses printing ink is used which usually
consists of different chemical components.
[0003] In most cases pigments, for example organic chromophores,
which absorb wavelength ranges of the light and consist of a
combination of carbon, oxygen and nitrogen and which are printed on
a substrate such as a web, are decisive for the colour impression
of the human viewer. The colour impression can be influenced or
provided also by polymers. Among them the so called long chain
hydrocarbons are the most important ones. The polymer chain
contains chromophore groups, which provide for the required colour
impression, after the cross-linking process of the polymers.
[0004] In many printing inks several of these colouring materials
are included. Hence the colour impression of the viewer of a
printing picture printed with such an ink is affected by several
optically active components. The printing substrate and the solvent
of the ink, which provides the main part of the volume of the ink,
has further influence on the colour impression of the viewer.
[0005] According to the state of the art the chemical composition
of printing ink is determined in central facilities ("ink kitchen")
of print officering plants. The ink is usually mixed according to
so-called ink formulas, which indicate the ink composition. After
the initial mixing process the ink is brought to ink reservoirs of
printing presses. The printing presses print with the ink.
[0006] It is also known how to take different kinds of measurements
which concern the printing pictures. For example optical measuring
instruments, which the person skilled in the art calls
"densitometer" or "spectral-photometer", analyze light, which has
interacted with the printing picture. The interaction between light
and substrate usually comprises a reflection or a transmission of
the light. Light which interacted with the printing picture (above
all reflection or transmission are relevant in connection with the
present disclosure) is called "remitted light" in the present
publication.
[0007] Densitometers as well as spectral-photometers measure the
intensity of light L (the remitted light) in a certain or
respective spectral region. In the case of a "densitometrical"
measurement different narrower spectral regions of the visible
light (e.g. nine spectral regions) are measured. In most cases
there are unmeasured gaps (spectral regions without measurements)
between these narrower spectral regions.
[0008] The densitometer comprises several colour filters, which
limit the light spectrum to a printed colour relevant for the
measurement. Usually, four colour filters for the printing colours
cyan, magenta, yellow and black are used. Behind each colour filter
there is a photoelectric sensor (photodiode). The densitometer is
used mainly for quantitative measurements of the colour density
(full tone density). During the measurement light is radiated on a
printed area and the remission and/or transmission value of the
light is measured often with a photoelectric sensor (photodiode)
after passing a colour filter. The measured values are used to
detect optical deviations of the printed measuring area from a
"colour standard". Among the optical features monitored are colour
deviation, colour depth of shade, contrast etc.
[0009] The more significant "spectrometric" measurement usually
contains measured values which cover the whole spectrum of visible
light. This broad spectral region is measured for example by 36
sensors with narrower spectral ranges.
[0010] Hence, the corresponding sensor, the spectral-photometer,
has the capacity to measure remission values of light in a spectral
region which covers the whole spectrum of the visible light. The
respective light has been reflected by the measuring area (usually
a printed substrate). Usually the measuring area is lit up with
suitable--in this case white--light.
[0011] Thus, the spectral-photometer measures the remission degree
of the sample (in percent) over the visible spectral range of the
light (approx. 400 to 800 nm). Usually, the measured values are
used to calculate the coordinates of the measured colour in a
colour space with a suitable software. The coordinates define the
so-called chromaticity coordinates of the colour.
[0012] The patent application EP 0,228,347 A1 discloses a control
method for the colour transfer onto a printing substrate, which
uses densitometrical colour measurement instead of a spectral
colour analysis. Measuring the spectral distribution of the colour
permits a very precise computation of corrective measures with
regard to the basis formulation of the ink. In this context a
suitable software can be used. However, the method shown in EP
0,228,347 A1 has some drawbacks. Usually, the use of that method
requires several correction cycles until the desired colour
impression is reached due to the ink corrections.
[0013] Therefore, the objective of the present invention is to
suggest a system and a method which allows a faster adjustment of
the printing picture than on prior art printing presses.
[0014] The invention is characterized by each of the patent claims
1, 16 and 20.
[0015] EP 0 228 347 A1 shows a method for the closed loop control
of the ink composition without measuring the ink viscosity. This
causes error in the colour impression after a long printing
time.
[0016] The second objective of the present invention is to suggest
a system and a method for measuring the viscosity of the printing
ink during the printing and ink correction process.
[0017] This objective is attained by patent claims 21 and 34.
[0018] The time periods required for taking measurements with a
spectral-photometer are not desired.
[0019] Therefore, the further problem to be solved by the present
invention is to minimize the time required for the
measurements.
[0020] The problem is solved by extrapolate densitometrically
measured values so as to imitate spectral photometric values.
Patent claims 40 and 48 recite the solution of this problem.
[0021] Advantageously, densitometrically measured values can be the
basis for determining an ink composition. The measured
densitometric values can be extrapolated in such a way that they
provide information as to not measured spectral areas. The quality
the values gained by the aforementioned extrapolation can be
checked by a comparison with (generic) spectral photometric values.
The respective spectral photometric values gain be gained from time
to time and compared with extrapolated values applicable for the
same moments of time
[0022] It is advantageous to use at least two ink mixing devices
for the ink correction on a printing press. One of these ink mixing
devices can be placed nearer to the printing press than the other
one. Moreover at least one of the aforementioned ink mixing
apparatuses can be provided with prospective corrective mixtures
which have already been mixed in advance.
[0023] With regard to the present invention it is useful to make a
difference between central mixing devices (generally called ink
kitchen or central ink kitchen) and decentralized mixing devices.
Usually, a centralized ink mixing device will deliver ink to more
printing presses than a decentralized one. A mixing device
comprises at least two ink containers containing ink compositions,
preferably however basic inks. A mixing device can supply ink
components from its containers. This dosing operation can be
controlled by weighing the ink bucket. The mixing operation can be
accomplished in an ink container like the ink bucket of the
printing press or even later by the ink pipe system of the printing
press.
[0024] A mixing device can also be mobile. In this case, its above
mentioned components are moved together with the entire device. If
the mixing device is mobile and has several dosing cocks and/or
gutter-pipes for ink mixtures and basic inks, the ink bucket of a
printing press can receive ink from varied dosing tap whereby the
mixing device can be moved in such a way that the dosing tap is in
a filling up position to the ink bucket.
[0025] Decentralized mixing devices can contain fewer basic inks
or, more general, fewer ink containers than the centralized mixing
devices. Therefore, it is favourable if a decentralized mixing
device contains at least 11 basic inks. A further container can
contain solvents. Additionally the central mixing device often also
contains decoration inks and the like.
[0026] The mobility of a decentralized mixing device can be
permitted by movement means such as wheels. A mobile decentralized
mixing device can be provided with drives, auxiliary drives and
steering or remote steering devices. It can also be equipped as a
rail-mounted vehicle.
[0027] A preferred decentralized mixing device comprises pumps for
transferring ink by means of ink pipes to an ink bucket. After
receiving a quantum of corrective ink the bucket contains the
corrective ink composition. It is most advantageous if this ink
bucket stands on a ink mass determination device, e.g. a scaling or
a weighing device, which measures the mass of the corrective ink
composition. This scaling device can compute the exact delivery
quantity (delivery volume) of the individual ink containers as an
additional control for the composition and mass of the corrective
ink composition. If the decentralized mixing device comprises
dosing means, and if the control device of the decentralized mixing
device is connected with the metering unit by a data line, it is
possible to monitor the corrective ink quantity in the ink
bucket.
[0028] A further preferential decentralized mixing device comprises
replaceable cartouches of basic ink. The form and the connections
of the respective ink cartouches are standardized, so that these
can be exchanged quickly. Advantageous decentralized mixing devices
comprise a compressed air mechanism. Compressed air can be used to
press the basic ink out of the ink cartouches by applying pressure.
In addition, compressed air can be used to clean the ink line or
pipe system and the decentralized mixing device (ink pipes) by
applying ("free-blowing") compressed air (without ink addition) to
the ink pipes.
[0029] It is also favourable if the decentralized mixing device
comprises an ink analysis device. Such a device can comprise a
spectral-photometer or a densitometer for receiving optically
measured values of the printing substrate. In addition, the ink
analysis device includes a control device, which is equipped with
an ink correction software or ink formulation software. Thus the
decentralized ink mixing device can make a correction on printing
machines. Such a decentralized mixing device equipped with all
favourable characteristics can also be called mobile ink correction
and analysis device.
[0030] A ink mass determination device can determine the mass of
the ink at least in a part of the ink pipe system. An ink pipe
system of a printing press transports the ink from an inlet place
to the printing substrate. The ink pipe system usually comprises a
bucket-like ink reservoir to which ink is supplied. Furthermore
pipes could be part of the ink pipe system. At least a part of the
pipes transports ink from the ink reservoir to other ink containers
or pipes.
[0031] Most ink decks contain ink containers which are often known
as ink troughs or doctor blade chambers. Particularly gravure and
flexographic printing presses comprise such containers which
transport ink to rollers which take part in the printing
process.
[0032] In flexographic printing presses the ink is often
transferred from a doctor blade chamber to an anilox roller which
delivers the ink to the printing plate cylinder. The printing plate
cylinder transfers the ink to the printing substrate. All
aforementioned reservoirs, containers, pipes and rollers which
transport ink to the printing substrate are in the following called
in their entirety ink pipe system or ink supply system. Therefore,
an individual ink pipe system is assigned to each colour of a
multi-colour printing press.
[0033] An exact measurement of the mass or volume of the ink at
each printing deck is complicated. However, it is feasible to
measure the mass or volume of the ink in the reservoirs and/or
containers by weighing the respective member as whole or by a
measurement of the volume (fill load of the ink in a reservoir). In
most cases, such a measurement will be accomplished with respect to
the ink bucket which is essentially the most important ink
reservoir. Such a measurement seems to be possible even in an ink
tray or in a doctor blade chamber. However, the vibrations of the
printing process have to be taken into account in this context. It
is favourable to estimate the mass or volume of ink contained in a
part of the ink pipe system. The estimation can be based on the
overall volume of the respective part of the ink pipe system.
[0034] A literal (additional) measurement of the ink mass and/or a
measurement of the ink volume (fill level) can be accomplished in
the bigger ink reservoirs or containers of the respective ink pipe
system. In most cases, the mass or volume of ink in an ink pipe
system will be detected on the basis of estimates and measurements.
In this way the mass of the ink existing in the ink pipe system (or
in parts it) can be identified very exactly with reasonable
effort.
[0035] These mass or volume values are supplied to the control and
evaluating device of a printing press. In view of the data
transmitting opportunities which are available for the man skilled
in the art, the exact position of the control and evaluating device
(on the press or in a certain distance) seems negligible or at
least of minor importance. The same notion applies to the position
of the hardware which provides for the "intelligence" of the
control and evaluation device. In any case, it is important that
the device is provided with a preferably electrical or electronic
data link to the measurement and control components of the printing
press. (At least with the ones mentioned in this printed
publication). It is advantageous, if such a link provides for the
possibility to control and to exchange data with different
functional units of the printing press. In this case the control
and evaluation device is deemed to be part of the printing
press.
[0036] The control and evaluation unit can determine the deviation
of the optical actual values measured by the optical measured
device and the optical reference values which are stored in the
device as light intensity values in a certain wavelengths
range.
[0037] The optical measuring devices can comprise spectral
photometers which provide for a very precise calculation of the
correction recipe or correction formula by means of a favorably
suited software. Moreover, densitometric measuring values can build
the basis for the preparation of a corrective ink composition.
These measuring values can be extrapolated in such a way that they
permit to give estimations on the light intensity in non measured
spectral ranges. On occasion, the quality of the densitometrical
measuring values and estimation and/or extrapolation can be checked
by means of spectral photometrical measuring values.
[0038] Favourable embodiments of control and evaluation devices
will convert the optical measuring values determined by the optical
measuring devices to colourmetric values at an earlier or later
date of the evaluation. The same applies to optical actual values
and setpoints.
[0039] Colourmetric measuring values are closely related to the
visual impression a human viewer gains of the printed image. Hence
the deviation of the colour of the printed image can be expressed
by a numeric value. The setpoint which should be reached during the
printing process can be expressed by means of a "numerical value"
(often called "chromaticity coordinate").
[0040] Owing to computed deviation of the colour and the weight of
the related ink in the press, the device calculates the mass and
the composition of the ink to be added in order to reach the
modification required. Here, the control and evaluation device
knows about the basic inks contained in each ink mixing and
weighing device and their effect on the light interacting with
these inks.
[0041] Favourably, the device does also know the effect of the
printing substrate actually handled at the printing press on the
remitted light.
[0042] By means of a software installed in the control and
evaluation device, the required values regarding mass and
composition of the ink can be determined. The control device of the
printing press is adjusted (i.e. programmed) in such a way that it
can determine the composition of the correction ink mixture owing
to the optical actual values and the ink mass values which are
transmitted to the control device as a signal and/or a data package
by the corresponding measuring devices. For this purpose, the
control device is equipped with interfaces permitting the control
device to transfer data regarding the composition of an ink mixture
to a central and/or decentral ink mixing device.
[0043] Such computed results (of the control device comprising of
the suitable software) acquired on the basis of colourmetrical set
points can form the basis of the basic recipe. When determining and
using the control recipes, the measurements mentioned before are
used for a control operation. During this operation the actual
values approach in one or several (iterative) steps to the
setpoints.
[0044] The determination of the ink mass in the ink circuit or
parts of it is very suitable to control how much ink (of the ink
mixed according to the basic recipe) is still on the press. At
least the part of the overall ink volume which has not yet been
transferred to any of the rollers (i.e. the ink in the pipeline,
reservoirs and containers) becomes a component of a resulting ink
composition. Therefore this part of the ink volume is important for
the effect of this ink on the light. Hence, the entire mass
measuring endeavour is very important.
[0045] The facts mentioned before show that it can be favourable to
only measure or estimate the mass of those parts of the overall ink
volume which is not yet at the rollers (ink transport rollers like
anilox rolls and pressure plate cylinder).
[0046] Additionally to the measuring and/or estimation of the ink
quantity, the measuring of the viscosity of ink in the ink piping
system is favourable. As already mentioned before, the ink consists
of several ingredients or components. Most importantly the colour
pigments and the solvents are to be mentioned. The characteristics
of the ink splitting and evaporation differ in all ingredients of
the ink (between the different pigments and between the pigments
and the solvents) so that their composition is altered during the
handling of an ink portion. Generally, the major differences exist
between solvents and pigments. So the portion of the solvent in the
ink can diminish considerably due to evaporation. This effect has
significant influence on the ink density and on the effect of the
ink to the light. A measurement of the viscosity does generally
permit a suitable conclusion as to the concentration of the ink
ingredients in the ink. Therefore, suitable corrective inks can be
mixed with higher accuracy. These corrective inks are to be added
to the ink volumes on the printing press.
[0047] As already mentioned, the steps mentioned above permit the
determination or at least the suitable estimation of the quantity
and composition of ink which is present on a printing press. On a
printing press according to the invention this also applies when
the first or already several portions of corrective ink of perhaps
different compositions have been added. The monitoring of the ink
composition is possible because the control and evaluation device
has the relevant information on the quantity and composition of
this corrective ink. It can be advantageous to save these
information.
[0048] By addition of the ink ingredients supplied and still
existing on the printing press and perhaps by checking the weight
and the viscosity, the control and evaluation device can keep
monitoring the mass and composition of the resulting ink.
[0049] As a result, it is possible to register and memorize with
which ink composition the printing has taken place at which date.
Furthermore, this original or resulting ink composition can be put
into direct relation to the (at this time) values (actual optical
values) measured at the printing substrate.
[0050] Thus, the operator can, gain something like a protocol of
the development of the ink compositions and the individual printing
results attained with certain ink compositions.
[0051] By the mixing of ink according to the dedicated resulting
recipes, the operator can specifically repeat those ink
compositions which have led to good results. Therefore, good
results can be repeated to a large degree by the same operation. It
has to be mentioned that a resulting recipe can be computed by an
analysis of the resulting ink composition and that it is favourable
to have the suited software installed at the control and evaluation
device. As mentioned above, the control and evaluation device
"knows" the quantity and composition of the corrective inks, and
advantageous control and evaluation devices save them. Thus, the
control and evaluation device can--as also mentioned before--keep
monitoring and hence controlling the mass and composition of the
resulting ink by addition of the added ink compounds. An additional
control of the weight and the viscosity has further benefits. As a
result the control and evaluation device can allocate assign to
measured actual optical values.
[0052] From a resulting ink composition at a certain time, the
resulting ink recipes can be determined stating how the said
resulting ink composition can be "directly" reached (e.g. as basic
recipe) by means of an ink composition. So the required
chromaticity coordinate can be gained "without detour".
[0053] Generally, it is useful to save the used recipes (especially
basic recipes, correction recipes). The respective measurements
(especially optical, advantageously also mass and viscosity) can be
saved, too.
[0054] Moreover, it is favourable to repeat several of the
measurements mentioned before within certain intervals.
[0055] It has already been stated that the use of the knowledge
gained on already used recipes (basic recipe, correction recipe,
resulting measured optical values) and especially of those recipes
leading to the resulting ink compositions can be favourable.
[0056] However, alternatively one can proceed as follows:
[0057] The deviations of the colour metrical setpoints from the
colour metrical actual values which have been recorded under a
printing process have also been saved. Often these values are named
as .DELTA.K. The different deviations measured until a satisfying
result has been reached are summated and added to the setpoint. By
means of the ink mixing software or ink formulation software
installed at the control and evaluation device, a basic recipe is
prepared which is optimized in order to reach the resulting
(sum-)chromaticity coordinate and not the set chromaticity
coordinate. The ink produced according to this "bypass recipe" is
used for the start up of the printing process.
[0058] The procedures mentioned for the use of a resulting ink
recipe or the bypass recipe are especially suited if the other
process parameters of the different orders (individual print jobs)
are mostly constant. These process parameters comprise the
following issues:
[0059] Same printing press, same anilox roll, same temperature
etc.
[0060] In the present publication the phrase "process for the
operation of a printing press" is used to refer to a process to
work off a single print job as well as a process for the sequential
work off of several print jobs. As a consequence, the phrase
"operation of a printing press" does also comprise the change-over
between two print jobs.
[0061] If several print jobs should effect the same colour
impression and/or the same setpoint (chromaticity coordinate) in a
colour space, it is favourable to rely on "experiences" from former
print jobs with the same colour setpoint. This finding applies even
if two different print shops to be accomplished by multi colour
printing presses have only one colour setpoint in common.
Especially the measuring values from these former print jobs belong
to useful "experiences". The ink compositions and the respective
ink recipes, corrective recipes and the resulting ink recipes can
also be mentioned in this context.
[0062] Especially with regard to the measuring values, the
deviations of the colour metrical actual values from the colour
metrical setpoints resulting from former printing jobs are
interesting. This notion applies especially with regard to the
values gained at the beginning of the printing job, when the
control system optimizes the printing picture by adding corrective
ink compositions to the ink volumes which are already on the
press.
[0063] As already mentioned before, it is possible to calculate ink
recipes (how do basic colours influence the light) by means of
preset colour metrical setpoints as well as by means of information
regarding the colour values of the basic colours by means of which
the chromaticity coordinate based can be calculated relatively
exactly. In order to make such calculations, the control unit of a
printing press can be equipped with a colour calculation software
(colour recipe software). The deviation of a chromaticity
coordinate which develops if the ink mix based on the recipe
calculated is used for impression setting (at the beginning of the
printing job) permits a whole set of conclusions on the calculation
method itself and on the process parameters.
[0064] Therefore, it is favourable to save the deviation and the
process parameters of such printing processes. Especially the
deviation is very interesting or significant. If one or more
correction cycles are required to reach the desired chromaticity
coordinate (colour metrical setpoint of a colour) with sufficient
accuracy, the further deviations (.DELTA.K.sub.1, .DELTA.K.sub.2
etc.) are interesting or significant, too. The different deviations
can be transferred into the coordinates of an ink area and be
summated by vectorial addition to a total deviation (.DELTA.K).
[0065] If data on a further (earlier) print job on the same
printing machine with at least one equal setpoint (e.c.
chromaticity coordinate) is at hand
the total deviation (of the earlier printing job) can be deducted
from the set point (chromaticity coordinate). Then, the difference
chromaticity coordinate (D=S-.DELTA.K) is delivered to the Ink
Formulation Software instead of the actual set point chromaticity
coordinate.
[0066] In case of a measurement of the mass of the ink existing at
the printing press it is possible to determine exactly in the way
mentioned before which deviation was measured when a certain ink
composition was converted by the printing press. It is
advantageous, if the control components of a printing press (press
operating system etc.) are adjusted in such a way that they can
execute the procedure. This adjustment is the result of the
installation of software components on the respective hardware
components.
[0067] Further details and examples are provided by the dependent
patent claims and the following description of the figures.
[0068] The individual figures show:
[0069] FIG. 1 A system for the supply of ink compositions
[0070] FIG. 2 A mobile (decentral) mixing device
[0071] FIG. 3 A further embodiment of the mobile decentral mixing
device
[0072] FIG. 4 An colour deck of a central cylinder flexo printing
press
[0073] FIG. 5 The distribution of the spectral light intensity of a
colour
[0074] FIG. 6 The distribution of the spectral light intensity of a
colour
[0075] FIG. 7 The distribution of the spectral light intensity of a
colour
[0076] FIG. 8 The distribution of the spectral light intensity of a
colour
[0077] FIG. 9 A vector addition in a colour space E
[0078] FIG. 10 A vectorial calculation of the set chromaticity
coordinates S in the colour space E
[0079] FIG. 11 A further system for the supply of an ink
composition
[0080] FIG. 12 A further embodiment of a mobile local mixing device
(colour correction and analysis equipment)
[0081] FIG. 1 discloses a system 1 for the supply of an ink
composition for printing on a printing substrate 6. System 1 also
provides for a possibility for correction of the ink composition.
The respective correction can also be accomplished during the
printing operation.
[0082] The printing press 2 comprises a control device 3 which is
connected via the control line 5 with an optical measuring device 4
which analyses the actually printed printing substrate 6. The cone
of light 7 signifies the light reflected by the printing substrate
6 which has interacted with the printing substrate. Only one colour
deck or printing deck 8 of the printing press is shown.
Notwithstanding this fact, the printing press 2 can possess of an
arbitrary quantity of colour decks. In case of a plurality of
printing decks, there are different methods to check the printing
picture by means of the measuring device. First of all special
printing marks can be examined. Those marks are printed into
distinctive areas of the printing substrate and/or the printing
picture. On the other hand, specially chosen areas of the printing
picture which are provided with one dominant colour can be checked.
However, during the impression setting process it is also possible
to check each individual colour sequentially.
[0083] The colour deck 8 of the printing press 2 is provided with
ink 11 from the ink bucket 10. The weight of the ink bucket 10 can
be checked by the weighing device 12. The weighing device can
transfer data on the ink mass via the control line or data line 14
to the control device 3. The ink quantity in the rest of the ink
supply system of the printing press can be estimated.
[0084] The ink lines 13 supply the ink to the colour deck 8. The
ink flow is controlled by the ink valves 15.
[0085] After the corresponding adjustment of the control device 3
(by an application of a suitable software) it 3 can record the ink
mass 11 in the ink bucket 10 continuously. Furthermore, it can
record the measuring values of the optical measuring device 4 and
allocate the optically recorded measuring values and the mass
values to each other. As long as the control device 3 "knows" the
composition of the ink on the printing press, it 3 is always able
to allocate which ink composition was used when certain colour
values in an colour space E were recorded at a certain time.
[0086] Additionally the viscosity measurement device 22 has to be
mentioned. This device 22 continuously measures the viscosity of
the ink at the printing press. Especially in gravure printing and
flexo printing machines the relation of the solvents in the ink and
the colour pigments may change during the printing process or
printing job. This effect can be attributed to different
vaporization characteristics of pigments and solvents. Such a
development can be observed sufficiently by the measurement of the
viscosity as solvents considerably diminish the viscosity in
general. If the viscosity measuring device 22 transfers its
measuring values to the control device 3 of the printing press
2--or another control device like the control device 19--in some
way, the respective control device has values regarding the actual
chromaticy coordinate at the printing substrate 6, the weight of
the ink 11 on the press 2 as well as of its 11 viscosity. Owing to
these measured values, the respective control system can provide
for a good survey on the composition and quantity of ink on the
press.
[0087] In general at the beginning of a printing process ink
compositions 21 for the diverse colour desks 8 are prepared or
mixed in the central ink kitchen. In this central ink kitchen there
are inks 17, mainly basic inks which are stored in suitable
reservoirs 18. In the embodiments shown these ink reservoirs 18 are
equipped with weighing devices 12. Alternatively, the volume of the
inks 17 can be measured by means of filling-level meters. The
weighing devices 12 and/or filling-level meters can transfer their
measuring values to the control device 19 of the central ink
kitchen 16 via a control line 14.
[0088] This control device 19 controls the composition of the inks.
In calculating ink recipes which are the basis of ink compositions
operators or control devices strive to reach the chromaticy
coordinate (setpoint) as exactly as possible. Based on the
information on the actual and desired chromaticy coordinate and on
the optical characteristics of the ink in the ink reservoirs 18 of
the ink kitchen 16 it is possible to calculate a recipe for
corrective ink composition for reaching a certain chromaticy
coordinate (setpoint) S. For this purpose, information on the
optical characteristics of the printing substrate is favourable.
The calculation mentioned can be accomplished by suitable software
programs. This software can be installed on the control unit 19 so
that this control unit 19 is adjusted for the calculation of an ink
recipe for attaining a colour setpoint S.
[0089] As already mentioned, the printing process starts in general
with the preparation of a basic ink composition in the central ink
kitchen. The ink is mixed according to a basic recipe, which can be
calculated for certain chromaticy coordinate setpoints in the
manner mentioned before. However, the basic ink compositions can
also be defined by the producer of the ink. This basic ink mixture
21 is transported to the printing press 2 in a reservoir 20.
Alternatively the ink can be conduced in a pipeline which is not
shown. The printing process starts with the basic ink mixture
21.
[0090] The printing images 9 are checked by means of the optical
measuring device 4. The measuring values often differ from the
chromaticy coordinate S by a certain value .DELTA.K. This fact is a
considerable drawback. Especially the printing on substrates for
packages requires high accuracy in this respect. In this area, the
flexo printing and gravure printing presses are the most common
printing machines; offset printing presses are also used.
Therefore, the printing press 2 can be a gravure-, flexo- or offset
printing press.
[0091] After computing the deviation .DELTA.K of the actual value
of the ink area from the setpoint of the chromaticity coordinate S,
it is possible to decide on the corrective measures. The aim is to
reach a higher compliance between actual value I and setpoint S.
However, this is especially difficult during the continuing
printing operation of a print job. The embodiment of the system 1
shown in FIG. 1 is provided with a decentralized ink mixing device
24 in addition to the central ink kitchen 16. The ink kitchen 16
can be allocated to several printing presses of a print office.
This ink mixing device 24 can be exclusively allocated to a single
printing press. In this case it can be combined or attached to the
machine frame of the respective printing press. However, such an
ink mixing device can also be designed for the provision of ink and
preferably corrective ink for several machines. In order to do
this, this unit 24 can be mobile, e.g. the entire unit can be moved
on wheels 34.
[0092] The decentral ink mixing device 24 comprises preferably 11
reservoirs with so-called primary and/or basic ink and a further
reservoir containing solvents.
[0093] FIG. 1 shows that the ink mixing device itself 24 contains
basic ink for correction 26, ink reservoirs 25, weighing devices 27
as well as ink lines or ink pipes 13 and ink valves 28. In general,
the decentral ink mixing device 24 stores smaller ink quantities
and a smaller numbers of different ink than the central ink kitchen
16. In this embodiment, a control device 23 is allocated to the
decentral ink mixing device 24. This control device 23 can control
the ink mixing or ink correction process by means of the
decentralized ink mixing unit 24. Therefore the control device 23
can actuate the of the ink valves 28 or other devices of the
decentralized ink mixing unit 24. Information regarding the
composition and quantity of correction ink can be sent to this
control device 23 via the control line 14, the intersection 29 and
the interface 30. Based on these information an ink recipe is
created, and the decentral ink mixing device 24 provides for a
corrective ink mixture for the printing press. This procedure is
symbolized by the arrow 31.
[0094] The correction ink can again be brought to the printing
press by using a movale reservoir. With regard to the basic ink
composition 21 this kind of transport is symbolized by the
reservoir 20 and the arrow 32. The supply of corrective ink from
the decentralized ink mixing device 24 to the printing press is
symbolized by the arrow 31. Again, an alternative transportation
method could make use of a piping system which is not illustrated.
If a mobile decentral mixing device 35 is used the device itself
can be brought to the ink buckets 10 of the printing press 2. Then
the corrective ink can be directly filled into the ink bucket 10 by
means of a discharge tap.
[0095] It has to be mentioned that the dots between the colour
reservoirs 18 and 25 denote the number of reservoirs 18 and 25 can
be bigger than shown in FIG. 1. In general, N basic colours 17 will
be available in the central ink kitchen while at least M colours 26
should be stored in a decentral unit.
[0096] Moreover, in the central ink kitchen 16 individual pigment
reservoirs can be provided which contain pigments for the
individual basic inks 17. By a mixing of the pigments of the basic
inks with solvents and further additives which are not described in
detail, basic inks 17 can be produced in the central ink kitchen
16.
[0097] Useful information can be exchanged if the control devices
3, 19 and 23 are linked so as to exchange data. Data gained by
measurement and/or estimation of the quantity of the ink 11 at the
printing press 2, by observation of the ink composition which can
be accommodated by optical measurements at the printing substrate 6
and/or by the measurements of its 11 viscosity, enable intelligent
devices such as the different control unites 3, 19, and 23 to
monitor the composition of ink at a given point in time T before
quantities of corrective ink are added to the basic ink.
[0098] By addition of a quantity and composition of correction ink
known by at least the control device 23 of the decentral ink mixing
device 24, the composition of the ink 11 at the press 2 is
considerably changed. After the first correction, this composition
can be calculated as correct as possible by an addition of the
quantities of the individual ink ingredients of the ink 11 at the
press 2 and the corrective ink 31.
[0099] This method can also be applied after several of such
correction steps. Therefore, it is possible to determine relatively
correct which ink mixture has generated which colour metrical
actual value I after an arbitrary number of correction steps. This
information is very useful if follow-up orders for further printing
jobs shall be printed with the same or similar colours (to be
determined by a comparison of chromaticity coordinates).
[0100] FIG. 2 discloses a decentral mobile ink mixing device 35
which could replace the decentral colour mixing unit 24 in FIG. 1.
The other reference 35 has been chosen for the mobile ink mixing
device to stress that the ink mixing device 35 is mobile while the
ink mixing device 24 in FIG. 1 may be stationary, too. However; the
functional components of the two mixing devices 24 and 35, the ink
reservoirs 25, the control line 14, the ink pipe 13, the control
device 23, the ink valve 28 and the interface 30 are referred to
with the same numerals. The functional components mentioned above
are supported by the frame and/or the rack 33 which is movable on
the wheels 36. Additionally, the brackets 34 show that the
functional components mentioned above are carried by the frame. The
decentral mobile unit 35 can be driven from one printing press to
printing press and can dispense corrective ink there. Thus, the
decentral mobile unit is able to dispense special portions of ink
which are stored in diverse ink reservoirs 25, to prepare a
corresponding composition of corrective ink and to dispense the ink
through the ink lines 13.
[0101] The mixing process of the different ink components can take
place in a non-shown mixing device of the decentral mobile unit 35.
However, the mixing can also take place in the ink bucket 10 of the
printing press 2. The control unit 23 receives information
regarding the corrective ink required. In the embodiment disclosed
in FIG. 2 the data exchanged is enabled by connecting the interface
30 of the decentral mobile ink mixing device to the interface 37 of
the printing press 2 which is to get the corrective ink. Via the
aforementioned interfaces, the control device 3 of the printing
press 2 informs the control device 23 of the decentral ink mixing
device 35 which deviations .DELTA.K at the printing substrate 6
have occurred and which colour composition was used during that
time. The control device 23 of the decentral ink mixing device 35
is provided with a "colour recipe software" in such a way that it
can calculate the composition and quantity of the colour mixture
which can be used for correction. This control unit 23 also "knows"
which quantities of corrective inks with which optical
characteristics are contained in the reservoirs 25 of the mobile
decentral mixing device 35. If a ink for adjustment of a correction
mixture is missing, because it is used up or did never exist from
the beginning, the control device 23 sends a corresponding
signal.
[0102] For the whole closed loop control purpose which is described
above, it is favourable to provide also data on optical
characteristics of the printing substrate 6 to the control device
23.
[0103] The above mentioned lines describe a very "intelligent"
control device 23. However, the data links between the control
devices 3, 19 and 23 in FIG. 1 show that each of the control
devices can be adjusted or programmed for the control of the
aforementioned method steps. The precondition is that the
respective control device has the necessary hardware capacity and
that the data lines 14 between the control devices 3, 19, 23 are
designed for a sufficient data transfer. The interfaces 30 and 37
may be Ethernet interfaces. However, it is favourable--especially
referring to the mobile decentral unit 35--if necessary information
is sent via radio or mobile phone frequencies (like UMTS, WLAN, IR
etc.). In the latter case, the control device 23 can be
continuously provided with information and the docking of the
interfaces 30, 37 is not required.
[0104] In most cases, the decentral ink mixing devices 24 and 35
will only provide for corrective ink compositions. However, as an
exception they will also provide for a basic ink mixture 21 (e.g.
for setting impression). One reason for such a use of an decentral
ink mixing device 26, 35 can be the provision of relieve for the
central ink kitchen 16.
[0105] In view of the conception or definition of the decentral
colour mixing devices 24, 35 one has to state that these devices
will in any case provide for colour and/or ink quanta. However,
there is no absolute need, that an actual mixing procedure of
different ink components our of a basic ink composition takes place
at these decentral ink mixing devices 24 and 35. There is a
possibility that the decentral mixing device provides for different
ink components which are filled in the ink buckets 10 of the
printing presses 2 concerned. Hence, the actual mixing
procedure-would take place in this bucket 10.
[0106] Especially with regard to the decentral ink mixing devices
24 and 35 it is advantageous if the reservoirs or ink pipes 13 of
the decentral ink mixing devices 24 and 35 are not provided with
already mixed corrective ink. The already mixed corrective ink will
inevitably contaminate the colour compositions for further jobs.
Therefore, it is advantageous to arrange the ink line 38 leading,
also mixed ink in the decentral ink mixing unit 35 in such a way
that it can be exchanged or easily cleaned.
[0107] In FIG. 3, a further embodiment of a mobile decentral ink
mixing unit 35 is disclosed. This unit 35 is provided with ink
pipes 38 which are downpipes 38. Each individual downpipe only
conducts ink 24 from only one ink reservoir 25. In most cases,
eleven colour reservoirs 25 are provided for the basic inks 24 and
a further reservoir 25 for the solvents. Each of these downpipes 38
has a ink valve 28 which can be controlled by the control device 23
via the control lines 14. The control device 23 checks also the
weight of the inks 26 by means of the weighing equipments 27. The
interface 30 is an antenna which is used for radio and/or (mobile
phone-) reception. The fixation of the different functional
components to the frame 33 is symbolized with the brackets 34 and
the mounting plate 39. The mobile unit 35 is moved to the ink
bucket 10 of a printing press 2 in such a way that successively one
or more downpipes 38 reach their filling position to the ink bucket
10 and the ink quantities are dispensed as calculated by the
control unit 23.
[0108] A solvent tank can also be part of such a mobile decentral
ink mixing unit 35. However, it is advantageous if such a tank is
directly at the printing press 2 and if solvent is put into the
corresponding ink bucket 10 if the viscosity sinks. In a system
like the one shown in FIG. 1 the control unit 3 of the printing
press (generally, this teaching is applicable for multi-colour
printing presses, therefore, there are often several ink buckets 10
at the printing press 2) can control the ink viscosity and provide
for a signal to add solvent to the ink when necessary.
[0109] In FIG. 4, a colour deck 8 of a central impression cylinder
flexo printing, press is shown. Machines of this kind are often
used in the packaging printing business. They are often provided
with eight to twelve of such colour decks 8. The scope of the
functional components of the colour deck 8 is indicated by the
rectangle 44. The application of the teaching of the present
printed publication to such a central cylinder flexo printing press
is advantageous. FIG. 2 shows the ink supply from the ink reservoir
which receives the ink from outside of the printing press--in this
case the ink bucket 10--to the printing substrate 6.
[0110] The ink pipes 13 are connect to the ink bucket 10 and the
doctor blade chamber 40. One of the ink pipes transfer ink to the
doctor blade chamber (as indicated by arrow 46) and the other one
13 conducts ink from the doctor blade chamber 40 back to the bucket
10 (as indicated by arrow 46). The ink circulation in the ink lines
13 of the printing press from and to the bucket 10 is often called
ink circuit. This phase--however--has a certain potential of being
misunderstood: The reason is that at least the ink which is printed
does never return.
[0111] Ink is sent from the doctor blade chamber to the doctor
blade 41 which turns in the direction of the arrow C. The doctor
blade 41 dispenses the ink to the cliche 43 of the cliche roll 42
which turns into the direction of the arrow B. By means of the
cliche, the printing substrate 6 is printed while it runs through
the printing nip 48 defined by the cliche roll 42 and the
impression cylinder 45.
[0112] The printing substrate is supplied in the rotating direction
A of the impression cylinder, passes the idler roller 49, is lifted
by the impression cylinder 45 and checked by the optical measuring
device 4. The cone of light 7 represents the light reflected by the
print image 9.
[0113] For the purpose of weighing or determination of the ink mass
and/or the ink volume of the corresponding ink at the printing
press FIG. 4 only shows one device: the weighing device 12 controls
the weight of the bucket 10. The ink pipes 13 could also be
weighed. However, it seems to be more useful to determine their
volume and to estimate or to calculate the volume of the ink in the
pipes. The doctor blade chamber 40 contains significant ink volumes
and could also be weighed. However, owing to the vibrations in the
colour deck there is no weighing device so that the moving takes
place analogue to the determination of the volumes in the ink
lines.
[0114] In the broadest sense, the ink at the rollers 41, 42 and/or
the cliche also belongs to the ink contained in a ink supply
system. However, only a fraction of the ink which once has been on
one of the rollers returns to the bucket 10 so that the volume of
this ink must not or needs not be considered for the purposes of
calculating the ink composition before or after adding corrective
ink volumes.
[0115] FIGS. 5 and 8 show the distribution of the spectral light
intensity of a chosen ink. A special ink or colour mixture
generates a characteristic distribution of the spectral intensity
of light which has an interaction with the colour and/or with the
printing substrate 6 printed with the ink. The curve (graph) 50
shows an example of such a sequence or distribution. A colour which
causes such a spectral intensity sequence of the reflected light
will generate a mainly blue impression to the viewer as the
intensity maxima of the curve 50 are within the range 380 to 550
nm.
[0116] The FIGS. 5 to 8 disclose the wavelength in nanometer (nm)
at the horizontal axis against the light intensity L in arbitrary
units on the vertical axis.
[0117] The areas 51 represent measuring values in the first chosen
wavelength areas. Measuring values in relative discrete areas are
caused by using measuring devices with a sensitivity depending on
wavelength. Suited or feasible semi-conductor components are known.
Often, they are equipped with filters for certain wavelength
ranges. In other cases only light from limited wavelength areas
blasts so that also only reflected light can be measured in these
areas. FIG. 5 shows that only a fraction of the spectrum is covered
by measurements. This is typical if so-called densitometric
measurements are taken. In these cases, light of nine or less of
the first chosen wavelength ranges which are of the whole spectral
range of the visible light (approx. from 380 to 780 nm) (in FIG. 5
only three in the range between 380 and 550 nm for demonstration)
is measured. It is decisive for the definitions provided by this
publication that wide areas 52 of the spectrum of the visible light
are not examined by these densitometric measurements. For the
purposes of this publication, these areas are also called "second
chosen wavelength ranges (52)" or "gaps (52)". They must be
distinguished from other wavelength ranges in which the light
intensity L is not measured. This is one of the reasons why such
measurements are only used for the control of the ink transfer to
the printed web according to the state of the art. The thickness of
the ink film transferred to the printing substrate can be modified
by a modification of the impression of the rollers which take part
in the printing process (especially in flexo printing presses), by
the adjustment of duct-adjusting screws (offset print) or by the
modification of the solvent contents of the ink.
[0118] Up to now, a modification of the mixing relation of
different colour pigments to each other (in an ink mix 11, which is
used in a colour deck 8) owing to such densitometric measuring
values is not known. In order to alter or re-adjust this mixing
relation of diverse ink pigments to each other (modification of the
basic recipe or modification of the ink composition on the press by
addition of correction colour), so called spectral photometric
measurements are required. FIG. 6 clarifies the nature of such
measurement. Additionally to the small number of first chosen
spectral areas 51, additionally chosen measuring areas 53 are
shown. Sometimes, kinds of chosen ranges overlap the whole range to
be measured spreading from 380 to 550 nm. Spectral photometrical
measurements, often have no "gaps" 55 or 52 between the chosen
ranges 51 and 53. In this case, the gaps 55 in FIG. 6 are only for
demonstration.
[0119] The spectral sensitivity areas 56 of the channels of a
spectral photometer 54 are shown on the lower horizontal axis 57.
The continuous string of sensitivity ranges (no gaps between those
areas) characterizes such a measurement (FIG. 8). Such spectral
sensitivity ranges can be limited to a spectrum of 10 nm allowing
conclusions concerning the intensity of the reflected light with
the respective resolution. In this case 30 to 40 channels would be
required to cover the whole spectral range of the visible light. A
semi-conductor sensor (e. c. photodiode)--in some cases provided
with an optical filter and/or other optical devices--has to be
assigned to each channel. The evaluation of the measuring results
requires the handling and processing of huge data quantities. Hence
huge calculation capacities are required. Therefore, it is
advantageous to extrapolate from densitometric measuring values to
spectral photometrical measuring values and to use the values
gained by the extrapolation also for the modification and/or
correction of the mixing relation of diverse ink pigments to each
other in an ink composition or a recipe. With the measuring values
of the I light intensity L in the first chosen range 51 at hand, a
first favourable step is to extrapolate to a light intensity L in
at least one wavelength range 52, 55 in which no measured values
have been taken. The extrapolated values are used for correction of
the pigment relation in the ink, perhaps together with the
measuring values.
[0120] This undertaking can be executed more reliably if the
"normal" sequence or distribution of the spectral light intensity L
of an ink or an ink mixture (at least exceeding a wavelength range)
which is shown in the figures by the curve 50 is known. Even
individual optical values (of very discrete or narrow spectral
areas) with respect to the normal distribution of spectral light
intensity L may be very useful.
[0121] In appropriate cases this process can be successfully used
to apply a densitometric measurement which measures the spectral
light intensity L--e.g. in only nine primarily chosen areas 51--for
the extrapolation of a complete spectral photometrical measurement
which is e.g. shown in FIG. 6 (if the gaps 55 are disregarded).
[0122] In FIG. 7 there is only one gap 52 within the whole
measuring range which extends from 380 to 550 nm. An extrapolation
within the range of this gap is also possible.
[0123] FIG. 8 clarifies the position of the graph 50 within the
whole spectrum of the visible light. Moreover FIG. 8 shows the
lower horizontal axis 57 which shows the continuous succession of
the spectral sensitivity areas 56 of a spectral photometer 54.
[0124] In the FIGS. 5 and 8 the lucency area or range of the
printed ink or colour is shown by the double arrow TB. The colour
reflection characteristic of the colour mixture is shown by the
graph or curve 50. The graph 50 describes the intensity sequence of
the reflected light in the ranges of the spectrum in which the
respective ink mixture possesses a detectable degree of reflection.
For the operator of a printing press, such a detectable degree of
reflection might be a degree of reflection which is still visible
for the viewer. As far as such a minimum degree of reflection can
be quantified across the whole spectrum of light in a uniform way,
it lies beyond 5%, however favourably beyond 2%. Within the lucency
range or area TB, the printed ink has a higher reflection degree,
i.e. the colour pigment layer transmits more light to and/or
through the printing substrate on reflection and/or
transmission.
[0125] For the purpose of the present publication it has to be kept
in mind that an extrapolation of an intensity sequence or
distribution of reflected light 7--as shown by means of the graph
50--can also be accomplished by means of a smaller quantity (three
in this case) for primary wavelength areas in which the measurement
takes place. One example concerns measurements taken with respect
to measuring areas 51 outside the lucency range TB of a certain
printed ink. For the purpose of correction of the composition of a
ink mixture 11 such measuring values can be omitted completely.
[0126] FIG. 9 shows the situation in an colour space E. Starting
from an origin O, which generally represents the desired colour on
the printing substrate, a colour mixing software which is installed
into a control device 3, 19, 23 calculates an ink recipe which
rules the composition of an ink 21 which is composed in a ink
kitchen 16. By means of this ink composition the operators of the
press desire to attain a cromacy coordinate (setpoint) S in a
colour space (e.g. LAB, XYZ, LUV, LCH). The control device 3, 19,
23 is provided with relevant information on the colour metrical
characteristics of the basic ink and the printing substrate as well
as the cromacy coordinate of said setpoint S in a colour space.
These information is the basis of the recipe to be prepared. The
mentioned ink mixture 21 is used for impression setting at the
beginning of the printing process. Measured values taken by an
optical sensor 4 reveal that the printed web has gained a colour
characterized by the actual cromacy coordinate (in spite of using
the ink mixture 21). There is a deviation .DELTA.K between the
actual cromacy coordinate I and the setpoint S. This deviation is
vectorially indicated by the value .DELTA.K. Conventionally the
scalar ".DELTA.E" is used which is the norm or magnitude of the
vector .DELTA.K in this case. However, the vector .DELTA.K is
better suited for the following purposes.
[0127] Some time after the above mentioned print job is completed,
a further one is going to be executed at the same printing press.
Both printing jobs or printing orders require the machine user to
produce a printing picture with the same setpoint S with the same
colour deck. Advantageously, the ink mixtures 21 as well as the
deviation .DELTA.K of the earlier print job have been saved for
this purpose.
[0128] The following arithmetic examples of the vector diagrams in
FIGS. 9 and 10 should be executed in a uniform colour space, e.g.
in the LAB colour space.
[0129] In the present example, the value -.DELTA.K is vectorally
added to the set ink area S. This results in the point or vector S'
which presents an auxiliary point in the colour space. It is
favourable to indicate the auxiliary point S' of the control device
3, 19, 23 as set ink area instead of the setpoint S. Then, the
control device 3, 19, 23 calculates a ink recipe which is
ascertained to reach the auxiliary point S' but at which the
setpoint S can be easily reached.
[0130] In more complicated cases several deviations .DELTA.K,
.DELTA.K.sub.1, .DELTA.K.sub.2, .DELTA.K.sub.3 can be used in the
same way in order to determine the auxiliary ink point S'. The
auxiliary point S' can be determined according to the following
formula:
{right arrow over (S)}'={right arrow over (S)}-.DELTA.{right arrow
over (K)}
.DELTA.{right arrow over (K)}=|.DELTA.{right arrow over
(K)}|({right arrow over (S)}-{right arrow over (I)})
[0131] FIG. 10 provides for a corresponding sketch.
[0132] FIG. 11 shows another example of a system 1 for the
preparation of an ink composition--and if necessary for the
preparation of corrective ink compositions. FIG. 11 has very much
in common with figure. Therefore the same numerals refer in both
figures to the same devices. As a result the following description
is confined to an explanation of differences between the figures
and/or systems. Unlike FIG. 1, FIG. 11 additionally provides for a
station 60 for the spectral photometrical examination of components
of the printing substrate 6 or the printing picture 9. This station
comprises a spectral photometer 54 which analyses parts of the
printing substrate 58 and which takes measurements as described
with regard to FIGS. 6 and 8.
[0133] Usually, the components of the printing substrate are not
analysed in an inline process with a spectrometer. This is to say
that there is--according to the state of the art--no spectral
examination when the printing press 2 is running (=running printing
substrate or printed web). In this case an enormous data quantity
would arise during a short period of time to ensure a measurement
with a certain quality. However, especially in view of the teaching
of the present publication it is advantageous to also measure
inline (running printing substrate 6, running press 2) with a
spectral photometer.
[0134] However, in view of the disclosure in the FIGS. 5 to 8,
densitometrical measuring values gained by the optical measuring
device 4 can be extrapolated so as to replace spectral
photometrical measuring values. On this basis, corrective recipes
or corrective ink compositions for one of the two mixing devices 16
and 24 can be gained (in fact central ink kitchen 16 and decentral
mixing device 24).
[0135] In most cases, two control circuits will be formed by the
said devices 16 and 24 and the other relevant components of the
system 1:
[0136] The impression setting is effected while using the ink
composition 21 prepared in the central ink kitchen 16. The recipe
which is the basis of this ink composition 21 can be set forth by
the buyer of the printed articles or by the manufacturer of the
ink. However, it can also be gained by an optically analyzing a
first model of the printing picture.
[0137] With respect to the analysis of the model the operator
should prefer the use of a spectral photometer 54 over a
densitometer.
[0138] The ink composition 21 which has been prepared according to
the recipe is transported to the printing press 2 and filled into
the ink bucket 10. The impression setting process is started with
this ink composition. (In some printing processes there is no need
for impression setting, so in these cases the start up of the
normal printing process starts). The resulting ink values are
measured on the running printing substrate 6. If the optical
measuring equipment 4 is a densitometer, its measuring values are
approximated in such a way that the results of the approximation or
extrapolation can be re-used at least in certain wavelength ranges
of the reflected light like spectral photometrical measuring
values. The measuring values are approximated in the spectral
ranges 52 of the reflected light 7. In these spectral ranges the
intensity of light has not been measured. The measured and the
extrapolated values are used for the evaluation of the actual ink
values. If this actual ink value lies within a target area around
the setpoint in the respective (preferably uniform) colour space
(which often is disclosed as a circle and/or a ball with a certain
radius which has the length .DELTA.E.sub.Set), there is no urgent
need to stop the printing operation. In any case a corrective
colour composition 31 is prepared which is also added to the ink
bucket 10. In most cases, this corrective ink composition 31 is
prepared by the decentral ink mixing device 16.
[0139] In regular or irregular intervals a further additional
measurement of the actual ink value I can be taken by the spectral
photometer 54. One good way to take such a measurement is to wait
for the inevitable exchange of a web storing or web winding roll
(or by taking off of a sheet in case of a sheet fed printing press)
printing substrate 58 can be retained and investigated in the
station 60. Especially in the case that during an offline
measurement (the printing substrate 58 is outside of the printing
press 2) an area of the printing substrate 58 can be precisely
analysed (e.g. by a spectral photometer), so that, the function of
the densitometer and the quality of the approximation can be
checked.
[0140] In FIG. 11, the arrow 59 symbolizes the transport of the
printing substrate 58 (which could be a part of a printed web or a
single sheet) into the station 60. The spectral photometer 54 is
connected to the other intelligent components of the system via the
control or data line 14 in a very sophisticated example of such a
station. It is also feasible if the spectral photometer is only
connected with the control device 19.
[0141] FIG. 12 shows a further embodiment of a decentralized mixing
device. In FIG. 12 the same or the functionally equivalent
components are marked with the same reference signs or numerals as
in FIGS. 2 and 3. In FIG. 12 additional, ink lines 64 are provided
which transport the basic ink 26 to the ink bucket 10. In order to
do this, the ink reservoirs 25 are filled with compressed air which
is conducted through a compressed air line which is not shown. The
ink bucket 10 is placed onto a weighing device 62. The measured
values (weight or mass of the corrective ink 31) are sent to the
control device 23 via a suitable data line.
[0142] Furthermore, the decentralised mixing device comprises an
ink analysing system 61 which contains an optical measuring
equipment 54. The measuring equipment takes optical measuring
values of the printing substrate 9 and sends them to the control
device 23. An ink mixing device 35 which comprises such an
equipment can also be named in its entirety as colour correction-
and analysis device. This colour correction- and analysis equipment
can accomplish a colour correction at printing presses which do not
comprise an optical measuring equipment for measuring colour values
on the printing substrate.
TABLE-US-00001 List of reference signs/numerals 1 System for supply
of an ink mixture 2 Printing press 3 Control and evaluation device
4 Optical measuring device 5 Control line, data line 6 Printing
substrate 7 Cone of light, light 8 Print work/colour deck 9 Print
image 10 Ink bucket, ink container, ink repository 11 Ink 12
Weighing device, ink mass detection device 13 Ink line, ink pipe 14
Control line, data line 15 Ink valves 16 (Central) ink kitchen 17
Ink (basic ink) 18 Reservoir for the inks 17 19 Control device 20
Reservoir for the basic ink mixture 21 21 Basic ink mixture 22
Viscosity measuring device 23 Control device of a (decentral) ink
mixing device 24 (Decentral) ink mixing device 25 Ink reservoir of
the (decentral) ink mixing device 26 Basic ink for correction with
a (decentral) ink mixing device 24 27 Weighing device of a
(decentral) ink mixing device, ink mass determination device 28 Ink
valve of a (decentral) ink mixing device 24 29 Intersection 30
Interface 31 Arrow "Transport of the correction ink mixture at the
printing press"/Corrective ink 32 Arrow "Transport of basic ink
mixture to the printing press" 33 Frame of mobile unit 34 Brackets
of mobile unit 35 Decentral, mobile colour mixing device 36 Wheels
37 Interface of the printing press 38 Downpipes 39 Mounting plates
40 Doctor blade chamber 41 Anilox roll 42 Cliche roll 43 Klischee
44 Rectangle 45 Impression cylinder 46 Arrow (ink supply direction)
47 Arrow (ink supply direction) 48 Printing nip 49 Idler roller 50
Curve/graph, optical values 51 First chosen areas or first selected
ranges 52 Not measured (wavelength)-areas ("gaps") or ranges 53
Additionally chosen measuring ranges 54 Spectral photometer 55
(Illustrating) Gap between measuring ranges 56 Spectral sensitivity
range of a "channel" of a spectral photometer 57 "Lower horizontal
axis" 58 Section of the printing substrate 59 Arrow "Transport
of/Information regarding section of the printing substrate" 60
Station for spectral photometrical test 61 Ink supply pipeline,
pipe, or piping 62 Weighing equipment of the decentral ink mixing
device 63 Decentral (mobile) colour analysis device of the
decentral ink mixing device 64 Ink lines of the decentral ink
mixing device, ink pipe of the decentral ink mixing device S
Chromaticity coordinate, ink setpoint, I Actual colour value S'
Auxiliary colour value K Correction vector O Origine TB Lucent
range, transparent area L Intensity D chromaticity coordinate
* * * * *