A system architecture that it is possible to set up print media production systems based on non-impact printing technologies. Such systems enable the entire printed product to be produced in-line. With non-impact printing technologies it is of fundamental importance that the print image is already dry after the print (as described for electrophotography with subsequent fixing or ink jet processes using special drying techniques or using hot-melt ink). In this way, finishing (collating, stitching and folding) can be done in-line, thereby making the intermediate storage of printed sheets superfluous.
A printing system that Printing Systems based on Non-Impact delivers a completely finished brochure copy by copy. The printing process is digitally controlled and a data file contains all the text, image, and graphics information to be printed page by page. Additions or modifications of this file are still possible shortly before printing starts, for example via the connected flatbed scanner. This production system could be summed up as a “data in-product out” system.
If printing systems based on non-impact technologies
are to be used, a full description of the printed product
is required in digital form.
The combination of text and images to form a Printing Systems based on Non-Impact page
occurs during the page “make-up”. In the production
of conventional printing plates the complete page is
put together manually by repro experts from text and
images that exist mainly as cut films.
The films are placed on a carrier sheet, adjusted for
position, and fastened in place. The quality of the print
depends directly on the precision and care of the makeup.
Register errors caused at this stage are unlikely to
be able to be compensated for later in the print. Film
stripping is carried out on a light table (see also fig.
1.2-24). Its work surface consists of a glass plate that is
illuminated from below Printing Systems based on Non-Impact with diffuse white light. Two
steel rulers at exact right angles, which may be moved
in parallel, are used to ensure accurate stripping.
In preparation for the stripping a millimeter sheet is
first placed on the light table with the carrier sheet on
top and fastened with adhesive tape. The carrier sheet
is a plastic film that is dimensionally stable, insensitive
to moisture, crystal clear, clean, and free of scratches
and should be as resistant as possible to build-up of
electrostatic charge. Polyester film with a thickness of
0.15 mm has proved useful for this purpose. Medium
and large-format assembly work (e.g., sheet assembly)
makes use of 0.3 mm Printing Systems based on Non-Impact film.
The several films are always mounted with the coating
facing uppermost so that during subsequent copying
exposure occurs coating to coating to avoid undercutting.
This means that for an offset plate wrong-reading
film copies must be produced. The films for text
and image are placed in the correct position according
to the layout and attached to the carrier sheet with liquid
adhesive or adhesive tape. In addition the films
must be cut to the required size without burring, using
for example a scalpel and a glass base or a film cutter.
The films on the carrier sheet must not overlap since
intimate contact between the film Printing Systems based on Non-Impact and the printing
plate will be affected by the thicker overlapping layers
of film during subsequent copying leading to undercutting during exposure of the plate and an imperfect copy (undercutting) (fig. 3.1-38).
Offset printing employs mainly positive printing
plates (see sec. 220.127.116.11). These require a wrong-reading
positive film assembly, during which difficulties may
occur due to the cut edges of the film, particles of dirt,
or dust as well as scratches and the edges of the adhesive tape, which act as image areas during platemaking by increased light absorption.
Adhesive tapes for fastening the film securely to the
carrier sheet are single-sided adhesive strips of 0.05
mm Printing Systems based on Non-Impact thickness. Crystal clear or light blue transparent
adhesive tapes are used for positive assembly. Despite
their thinness, they still disrupt the direct contact between the film and the printing plate during platemaking, which may lead to undercutting. Adhesive tapes must therefore only be placed on an image-free margin on the film that is sufficiently wide; there should be a minimum of 5 mm between the edge of the image and the tape. The adhesive strips must also be cut burr-free.
If there is insufficient space available the film must be
attached to the carrier sheet with a liquid adhesive Printing Systems based on Non-Impact or a
The assembly of multicolored images must be carried
out with particular care as imprecision translates directly into register errors. In particular, errors of parallax caused by registering the color separations when viewing from an angle must be avoided. It is possible to improve precision during assembly by using a magnifying glass (pocket lens) or a microscope, which enlarges the image element under scrutiny and automatically provides a vertical viewing angle.
Two technologies have become established in the assembly of color separations:
• Guide assembly. A guide assembly is first produced
with the separation films of the color having the
clearest visible details Printing Systems based on Non-Impact. It acts as a base for all of the
other separations that are each mounted on other
carrier sheets. The contrast between the guide assembly
and the separation being worked on is improved if a matte film is placed in between to make the guide assembly appear gray.
• Blue key. Better registration is achieved by this
process. A positive or negative blue key is produced
from the guide assembly on precoated light-sensitive
plastic film. The light-sensitive coating is dyed
blue or bluish red; the dye is transparent to the
copy light. The separation is mounted on this film.
Cut edges and minor imperfections during Printing Systems based on Non-Impact positive
platemaking are exposed away by placing a dispersion
sheet/foil in between (fig. 3.1-39).
Negative assembly (i. e., ink-carrying/image areas appear light in the film) is frequently used in newspaper production. Dark brown or black adhesive tape is used to mount the negative films on the carrier sheet. The whole assembly area is covered with a backing sheet that is transparent on the light table but opaque to the UV-containing copy light. The backing sheet is cut away in all the image areas, which means there are no defects caused by cut edges or dust as may occur during positive Printing Systems based on Non-Impact platemaking. An imperative for negative assembly is that the image areas are perfectly transpar- ent (D2.5).
Since manual registration of four-color images is dif-
ficult in negative assembly and is therefore fraught with greater errors, it is used predominantly for single-color work. It is advantageous to copy the images during a second stage in exposure onto a plate that has already been exposed with the text and graphics. The image areas are blackened out in the text film copy and the plate at first remains unexposed in these areas during copying. Alternatively, the non-image areas of Printing Systems based on Non-Impact the image film copy are black in order not to destroy
the already exposed areas of text by a double exposure.
For quality control a blueprint proof is produced
from each finished assembly,which is used to check the
position, completeness in all color separations, and the
text and image. These checks should be carried out very carefully as changes to the assemblies during the makeup stage may be made without a great deal of extra time, or financial or personal expenditure. 18.104.22.168 Sheet Assembly
If the ready made-up films (text and images are put together
in the correct position) are available for all pages
(full Printing Systems based on Non-Impact-page film), such as in the form of manually created
assemblies or as electronically made-up full-page
films output by the imagesetter, they must be mounted
as a full-sheet size film, corresponding to the sheet
to be printed. The positioning of the full-page films in
sequence and orientation as well as the precise location
of the individual pages on the sheet must be established
by taking into account the following list of points (in
addition other control and editing elements must be
added to the assembly):
• printing process (halftone film copy for autotype
printing processes, continuous-tone copy for variable
depth gravure printing; right-reading film for
direct Printing Systems based on Non-Impact printing processes, wrong-reading for indirect;
positive film for positive-working plates, negative
film for negative plates),
• type of printing press (gripper edge for sheet-fed
machines; pin edge, roller gaps, register marks,
transverse register balance of stretching due to humidity for web-fed machines),
• print format of the press used,
• method of turning the sheet for printing on both
sides (work and tumble with sheet-fed presses
equipped with a perfecting unit; work and turn or
work and tumble with sheet-fed presses without
perfecting unit; simultaneous printing on both
sides with presses equipped with blanket-to-blanket
• imposition diagram of the Printing Systems based on Non-Impact folding machine or
• method of binding the whole printed product (allowance in the inside margin for cutting off the
folds in adhesive binding),
• method of finishing (overfold for gathering or inserting drum processing in the dispatch room),
• direction of paper travel (long grain, short grain
paper for sheet-fed presses, see fig. 1.5-3, portrait or
landscape formats for web presses),
• position of the folded sheet in the end product
(arrangement of page numbers, e.g., one to thirty
two on the first sheet as well as on the pages for the
• number of colors per side of sheet,
• auxiliary marks (registration marks, trimming
marks, folding marks, allocating marks Printing Systems based on Non-Impact, register
marks, signature line, color identification, ID
• control patches (print control strips crosswise to
the print direction over the total width of the sheet,
copy control wedges on a non-printing area of the
Other specifications must be observed according to the
This makes sheet assembly stand out as an information- gathering point of central importance for achieving trouble-free results. Although the handling of each individual stage is almost identical to page assembly, the content is much more comprehensive.
The first step in producing a sheet assembly [3.1-7,
3.1-12] is to draw a layout sheet containing the correct
measurements (fig. 3.1-40). It is Printing Systems based on Non-Impact the same format as the
sheet with an additional border and is made of dimensionally
stable transparent material/paper. If we take a
layout sheet for a sheet-fed offset press as an example,
after positioning on the light table parallel to the axes
and fastening with adhesive tape, the sheet format,
gripper edge, the beginning of the print, and the center
line are marked in. The data required for this are in
the documentation referring to the press or may be obtained from the job itself.
According to the measurements given in the imposition
diagram (which should be checked in each case
with the aid of a Printing Systems based on Non-Impact hand-made folded sample) the exact
outlines of all of the pages to be accommodated on the
top surface of the sheet must be accurately drawn, in
reverse (wrong-reading). These include the distances
between the pages taking into account allowances for
folding and trimming. The page number must be
entered in the bottom outside corner of each page.
This clearly indicates the position and orientation
(upright or upside-down) of each page. After marking
in the position of the control elements and auxiliary
marks, the layout sheet is complete. Cut and fold marks
should be designed so that they cannot be confused
during the finishing process and so Printing Systems based on Non-Impact that they cannot be
seen on a final print that has been badly trimmed.
Color control bars should be placed in the border so
that they can be trimmed away from the print. The
space for the sheet signature, the ink description and
the ID number must be marked.
For the reverse side of the sheet the layout sheet should
be marked according to the same considerations while
taking account of the type of inversion to be used. Hence two layout sheets must be produced for each sheet.
For the sheet assembly the layout sheet is accurately
positioned and fastened on the light table – if Printing Systems based on Non-Impact necessary
with a millimeter grid placed underneath. A carrier
sheet/assembling film is placed and positioned above.
The completely assembled films for the individual pages are registered on the layout sheet and stuck down. As with page assembly, sheet assembly of process color sets is carried out either using guide assembly technology or with a blue key.