Printing – Print plate feeding or delivering
Reexamination Certificate
2000-07-25
2002-11-05
Colilla, Daniel J. (Department: 2854)
Printing
Print plate feeding or delivering
C101S415100
Reexamination Certificate
active
06474236
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a plate making apparatus using a plate material having flexibility. In addition, this invention relates to a printing method, a printing apparatus, and a packing sheet material for a printing plate material according to a planographic printing technique. Further, this invention relates to a plate material placement method and a plate material placement apparatus for placing a plate material on a plate cylinder of a printing apparatus or a plate making apparatus.
In a planographic printing printing apparatus, generally a printing plate is wrapped around a plate cylinder and is fixed mechanically and printing is executed in this state.
However, a planographic printing plate with an easy-to-handle material other than metal (for example, plastic film, paper, etc.,) as a support has a drawback in dimension stability. For example, the plate warps partially by the friction between a blanket cylinder and the plate during printing and print dimensions and print position accuracy relative to paper are impaired.
Therefore, hitherto the plate using a support material as described above has been limited to simple use for printing a small number of sheets not much requiring register accuracy of printed matter and has not been used for high-grade printing of multicolor and elaborate printing or full-scale printing using a large printing apparatus.
To solve such a problem, Japanese Utility Model Unexamined Publication No. Sho. 58-1046 (JP-A-58-1046U) proposes a method of bonding a plate material directly to a plate cylinder or a preparatory form plate using an acrylic or rubber both-sided adhesive sheet or spray adhesive, for example.
However, in such a method, the printing plate is strongly bonded to the plate cylinder, thus a new problem occurs, namely, the position of the printing plate on the plate cylinder cannot be finely adjusted or workability of discharging the plate after print, etc., worsens extremely.
On the other hand, plate making and print method by CTP (computer to plate) finding spreading use in recent years have advantages that dimension, position accuracy of an image (exposure) relative to a plate material is good and that registration in multicolor printing is easy as compared with conventional plate making and printing method (exposure step of plate material is contact exposure using a lith type film).
However, the planographic printing plate having the support made of a plastic film, paper, etc., as described above involves the problems as described above, thus the advantage that registration in multicolor printing is easy in the CTP is not used fully.
On the other hand, hitherto, various techniques for placing a plate material on a plate cylinder of a printing apparatus, etc., have been known.
FIGS. 23 and 24
show a printing plate placement apparatus
260
for placing a plate material on a plate cylinder of a printing apparatus.
FIG. 24
is an X arrow view in FIG.
23
and
FIG. 23
is a sectional view taken on line Y—Y in FIG.
24
.
As shown in
FIG. 23
, a plate cylinder
261
of a printing apparatus has a shape such that a part of a column is cut in an axial direction of the column and that a groove part
265
is made in a roughly flat plane of the cut end, which will be hereinafter referred to as flat face part
261
a
. Provided in the groove part
265
are a plate front clamp mechanism
262
for clamping the plate front of the front end of a printing plate
270
and a plate back clamp mechanism
263
for clamping the plate back of the rear end of the printing plate
270
. The clamp mechanism
262
(
263
) comprises a lower tooth
262
b
(
263
b
) with the top face forming roughly the same flat face as the flat face part
261
a
and an upper tooth
262
a
(
263
a
) being supported on the lower tooth for rotation and capable of clamping the plate front between the upper tooth and the top face of the lower tooth.
Peak parts
261
c
are formed between the flat face part
261
a
of the plate cylinder
261
and a curved surface part
261
b
. With some plate cylinders, peak parts may be formed between the lower tooth top face of clamp mechanism in place of the flat face part and curved surface part although not shown Normally, the portion where the flat face part
261
a
and the curved surface part
261
b
cross each other is rounded as a curved surface having a radius of 10 to 20 mm, but such a portion will also be called peak part in the specification.
As shown in
FIG. 24
, the lower tooth
262
b
of the plate front clamp mechanism is formed on the top with two positioning pins
264
spaced from each other in an axial direction of the plate cylinder
261
. Notches
266
are formed at the positions of the upper tooth
262
a
of the plate front clamp mechanism corresponding to the positioning pins
264
. Notches
271
are also formed at the positions of a plate front
270
a
of the printing plate
270
indicated by phantom lines in the figure corresponding to the positioning pins
264
.
By the way, needs for plate materials made of inexpensive and easy-to-handle material other than metal, such as plastic film or paper, which will be called flexible plate materials in the specification, have grown with recent small lots and versatility of print matter. However, since such plate materials are highly flexible, several problems occur when the plate material is placed on a plate cylinder.
For example, in the printing plate placement apparatus
260
, when the operator inserts the plate front
270
a
of the flexible printing plate
270
shown in
FIG. 24
between the upper tooth
262
a
and the lower tooth
262
b
of the plate front clamp mechanism while holding the plate back
270
b
of the printing plate
270
and abuts the plate front against the two positioning pins
264
, the plate front
270
a
may become deformed and be fixed in this deformed state. That is, in a plate cylinder on which a printing plate of a royal octavo or larger can be placed, the spacing between two positioning pins
264
becomes considerably wide and at the printing plate placing time, if the operator over pushes the flexible printing plate
270
even a little, the printing plate
270
becomes deformed so that the plate front
270
a
projects in the push direction from between the two positioning pins
264
. However, if the printing plate
270
is pushed insufficiently for avoiding such deformation, it cannot be positioned accurately.
As shown in
FIG. 23
, the flexible printing plate
270
is hard to be conformable to the outer peripheral surface of the plate cylinder
261
and tends to float up from the outer peripheral surface of the plate cylinder in the proximity of the peak part
261
c
formed between the flat face part
261
a
and the curved surface part
261
b
of the plate cylinder
261
.
To prevent such floating of the printing plate
270
, while strongly pulling the plate back of the printing plate whose plate front is clamped in the plate front clamp mechanism
262
, the operator rotates the plate cylinder and places the printing plate
270
thereon. At this time, however, the pulled part of the plate back of the flexible printing plate
270
is extended.
As in the example, the placeability of a flexible plate material on a plate cylinder is poor and it is difficult to always place a flexible plate material on a plate cylinder in a constant state. Therefore, if the flexible plate material is applied to multicolor printing (for example, four-color printing), etc., requiring a number of plate cylinders and accurate registration among the plate cylinders, an out-of-registration phenomenon occurs.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to solve the above-mentioned problem.
It is an object of the invention to provide a plate making apparatus which uses a planographic printing plate comprising a plastic film, paper, etc., as a support and reliably holds a plate material on a plate cylinder and accurately positions the plate material on the plate cylinder, thereby enabling multicolor planographic prin
Nakayama Takao
Naniwa Mutsumi
Sera Hidefumi
Colilla Daniel J.
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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