Ink flow rate indicator

Details Ink flow rate indicator Ink flow rate indicator

1998-05-27

2001-11-20

Asher, Kimberly (Department: 2854)

Printing

Processes

Plural impressions on single article

C101S366000, C101S183000, C101S210000, C101S211000

Reexamination Certificate

active

06318266

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to control of the ink flow of a printing press.
BACKGROUND OF THE INVENTION
The prior art printing process is illustrated in
FIG. 1
to which reference is now made. Each individual color page to be printed is prepared on a pre-press device
10
. When the designer finishes designing the page, the pre-press device
10
creates four digitized versions
12
of the page, one for each of the four color separations cyan, magenta, yellow and black (C, Y, M, and K). The digitized versions of the page will be known herein as “separation files”
12
.
When the designer has finished preparing all of the pages of the printed publication (magazine, newspaper, brochure, etc.) to be printed, he provides the separation files
12
for the entirety of pages to an imposition device
14
(such as provided within the WHISPER I/O Station manufactured by Scitex Corporation Ltd. of Herzlia, Israel) which “imposes” the pages into “signatures”
16
. Each signature typically has press marks
18
and eight pages on it where the order that the eight pages are laid out is a function of how the printing press will fold the press sheet after printing. The imposition device
14
produces four data files of the signature, one for each color separation.
The four files representing the signature
16
are provided to a film plotter
20
(such as the DOLEV 800 plotter manufactured by Scitex Corporation Ltd.) which plots each version of the signature
16
onto a film. The result are films
22
of the separations of the signature
16
. Blue-line proofs
26
are provided by blue line proofer
26
from films
22
. Blue-line proofs
26
is a blue and white print of the signature
16
and is utilized to ascertain that the text is correct, that the placement of the various elements of the pages are correct and aligned and that the general impression of the pages is correct. If it is not, the designer needs to make changes at the pre-press device
10
and the process needs to be repeated.
To determine whether or not the colors to be printed are the desired colors, the films
22
are sent to a Chromalin proofer
26
as produced by Dupont, Delaware, USA for producing a color CHROMALIN proof
29
. The film creation process is repeated if the colors are in any way unacceptable.
If the blue-line proof
26
and the color chromalin
29
indicate that there are no problems, the films
22
are provided to a printing press
30
for printing. Each film
22
is utilized to create a press plate and the press plates are placed on separate inking units of the press, onto which the ink of the proper color (cyan, magenta, yellow or black) will be spread.
Since the color varies widely across a page and across a signature, each press inking unit is divided into a plurality of “zones” where each zone has a separate ink flow regulator
32
, known as a “zone valve”. Each zone valve ensures that the amount of ink which is spread across its zone is compatible with the amount of color desired.
Usually, a press operator initially sets the zone valves
32
by looking at the colors in the Chromalin proof
29
. He then prints one sheet with the initial settings, to view the final result. If the colors are smeared in one zone, there is too much ink available and he will have to adjust down the zone valve
32
for the problematic zone. Similarly, if the color is too light, he will have to open up the zone valve
32
. The printing process is repeated for another sheet until the desired affect is achieved. After that, the printing press is operated with only spot checks to determine that the ink flow in each zone remains correct.
The Heidelberg Speedmaster 72 printing press, manufactured by Heidelberg Druckmaschinen AG of Germany, has a plurality of zone valves
32
(or fountain keys) which can be controlled directly or remotely. Presses may have 8 to 30 such zone valves.
It will be appreciated that, if the density of a given color is consistent across the zone, the setting for the zone valve
32
is straightforward. However, if the density of the color varies widely over a zone, it is difficult for the press operator to determine how much ink flow to provide.
U.S. Pat. No. 5,128,879 describes a method and apparatus which acquires the zone valve states and adjusts them automatically. The settings of the zone valves are calculated from the color density values provided in the page initially created by the pre-press devices
10
. The calculated zone valve settings are forwarded directly to the printing press, without intervention of the press operator.
European Patent Publication 495563 A2 describes an integrated computerized system for use in printing assigned to the common assignees of the present invention. The disclosure of its U.S. counterpart, allowed application No. 07/650,249 now U.S. Pat No. 5,875,288 is incorporated herein by reference. The system includes apparatus for providing and digitally storing at least one digital representation of at least one page. The digital representation is imposed and arranged in accordance with a desired plate layout to define a plate image. Press set-up apparatus then extracts the digital representation and providing press set-up data to a printing press.
SUMMARY OF THE PRESENT INVENTION
This invention is useful in printing presses which are manually (or remotely) controlled. It is an object of the present invention to provide the press operator with positive indication of the initial setting for the printing press zone valves. This is achieved by creating a proof which provides, in addition to a proof of the signature (placement, text, graphics), ink density indications for each zone of each color separation.
According to a preferred embodiment of the invention, there is provided a method for providing indications for conditioning or presetting ink flow valves of at least one inking unit of a printing press. The printing area of the inking unit is divided into a multiplicity of inking zones each supplied by one ink flow valve in order to prescribe a predetermined rate of ink flow for each ink zone in said at least one inking unit. The method includes determining by calculating, from a digital image being processed for printing, a representative ink density value for each ink zone and for each color separation and furnishing the ink flow valves respectively with the values for regulating the flow in the ink zones.
The ink density indications can be provided in any way. In one embodiment, the ink density indications are provided in strips, one per ink color, below the signature. The strips are divided into sections, one per zone, and each section has both a listing of the ink density of the zone and a swatch of ink having the average color density.
Moreover, in accordance with the preferred embodiment of the present invention, the representative ink densities are determined by dividing the image to be printed into a plurality of image zones associated with the inking zones of the press and determining a representative ink density of each ink color in each image zone. The operator is typically furnished with a reproduction of the representative ink densities as color proofs or alternatively on paper.
Furthermore, in accordance with the preferred embodiment of the present invention, the reproducing of the representative ink densities includes the step of creating color strips of the representative ink densities. The color strips have strip zones each of which is associated with one of the image zones. The strip zone has the representative density of the associated image zone. Numerical indications of the representative ink densities can be included. The step of reproducing can include the step of plotting the representative ink densities on a color proof or onto color separation films from which a color proof is produced.
Furthermore, in accordance with a second preferred embodiment of the present invention, there is provided a method of setting the amount of ink flow for each zone valve of a printing press for an image to be printed. The method includes

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