Printing – Rolling contact machines – Rotary
Reexamination Certificate
1999-08-24
2001-06-12
Colilla, Daniel J. (Department: 2854)
Printing
Rolling contact machines
Rotary
C101S177000, C101S178000
Reexamination Certificate
active
06244176
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a printing apparatus for continuously printing a seamless continuous pattern on wall paper, corrugated cardboard, color wrapping paper, face steel plate, etc.
The conventional offset printing is performed by rotating in mutual contact a plate cylinder, a blanket cylinder and an impression drum.
FIG. 1
shows a concept of sheet-fed offset printing machine. As shown in the drawing, the offset printing machine includes a plate cylinder
1
, a blanket cylinder
2
and an impression cylinder
5
. The plate cylinder
1
is formed of an aluminum cylinder having a thin aluminum sheet wound thereon as a printing plate. A photosensitive resin layer having a compatibility with an ink is formed on the thin aluminum sheet. A rubber blanket sheet (not shown) is attached to the blanket cylinder
2
by a metal fitting bar. An oil-resisting surface rubber layer for performing an ink transfer is formed on the rubber blanket sheet.
A groove
3
is formed on each of the plate cylinder
1
and the blanket cylinder
2
, with the result that a blank portion in which the printing is not performed is formed on a printing medium
4
such as a paper sheet. The impression drum
5
serves to transfer in a predetermined direction the printing medium
4
held between the blanket cylinder
2
and the impression cylinder
5
. An ink is supplied from an inking device
6
consisting of a plurality of rolls
6
a
,
6
b
,
6
c
,
6
d
,
6
e
and
6
f
onto the plate cylinder
1
.
The rubber blanket for the conventional offset printing machine is prepared in a length of several hundred meters and, when used, the long rubber blanket is cut to meet a required machine size. In general, the rubber blanket is prepared by bonding
2
to
4
woven fabric sheets with a rubber paste, and the surface rubber layer is heated in a vulcanizer for the vulcanization. Then, the surface rubber layer is polished to have a required thickness, thickness uniformity and surface roughness.
FIG. 2
exemplifies an offset rotary press including a plurality of units. Each unit comprises a pair of blanket cylinders
12
having a web paper
14
held therebetween, plate cylinders
11
positioned in contact with the blanket cylinders
12
, inking devices
13
for supplying an ink to these plate cylinders
11
, and dampening units
15
. Printing can be performed on both side of the web paper
14
simultaneously. If the paper sheet
14
is passed through four units continuously, four color printing can be performed on both surfaces of the paper sheet
14
. The particular offset rotary press is widely used for the printing of news paper advertising paper sheets, etc.
A printing plate and a rubber blanket are mounted in the form of a sheet to each of the plate cylinders and the blanket cylinders in the case of the offset rotary press, too, with the result that a blank portion in which the printing is not performed is formed in a width of about 10 mm. Also, the thickness of the printing paper sheet used is limited to about 0.1 mm or less, making it impossible to carry out the printing on a corrugated cardboard or a steel plate.
FIG. 3
shows a concept of a flexographic press. The flexographic press comprises mainly an ink pan
21
housing an ink, a rubber roll
22
having a part thereof dipped in the ink housed in the ink pan
21
, an anilox roller
23
having fine cells formed on the surface, a doctor blade
24
for removing an excess ink, an plate cylinder
26
positioned adjacent to the anilox roller
23
and having a flexographic printing plate
25
formed on the surface, and an impression cylinder
28
. A printing medium
27
such as a corrugated cardboard or a plastic film is held between the plate cylinder
26
and the impression cylinder
28
.
In the flexographic press, an ink is supplied from the rubber roll
22
to the anilox roller
23
, and an excess ink is removed by the doctor blade
24
such that a required amount of the ink is supplied to the flexographic printing plate
25
. Further, the ink is transferred from the flexographic printing plate
25
onto the printing medium
27
so as to finish the printing operation. In the flexographic printing, the printing plate is prepared by forming a manual or laser engraving on a soft and elastic material such as a rubber plate or a photosensitive resin plate. However, the flexographic printing is far inferior in the printed image quality to the offset printing.
The printing plate for the offset printing is prepared by coating an aluminum plate with a lipophilic (compatible with ink) photosensitive resin, followed by exposing the photosensitive resin layer to light through a negative film so as to fuse the non-image portion. As a result, the non-image portion is exposed to the outside so as to be made hydrophilic. The most excellent image quality can be obtained by the offset printing among the various printing techniques available nowadays partly because the image quality is determined by the magnitude and area ratio of the dot and partly because the ink is transferred to the printing medium such as a paper sheet through a rubber blanket. In the offset printing, the rubber blanket is said to be the most important factor for determining the quality of the printed image.
Recently, a blanket in which a porous rubber layer is interposed as a compressible layer between adjacent woven fabric sheets is mainly used in the printing field. The entire thickness of the blanket generally falls within a range of between 1 mm and 2 mm, and the actual thickness is determined to meet the specification of the printing machine.
In the ordinary offset printing machine, the printing is performed successively with inks of four colors, i.e., black, cyan, magenta and yellow, by four units so as to obtain a colored print. In the conventional offset printing machine, however, a groove is formed in each of the plate cylinder and the blanket cylinder for attaching a sheet-like printing plate and blanket to these cylinders. It follows that the size of the print is limited. For example, it is impossible to print a continuous pattern on a large and thick printing medium such as a wall paper sheet wrapping paper or a face steel plate.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention, which has been achieved as a result of an extensive research made in an attempt to overcome the above-noted difficulties inherent in the conventional offset printing, is to provide a printing apparatus which permits printing a continuous pattern on a large and thick printing medium by transferring in a superposed fashion images of multi-colors onto the same blanket so as to achieve printing on the printing medium in a single operation.
According to one embodiment of the present invention, there is provided a printing apparatus comprising a driving roll, a supporting roll, an endless offset blanket stretched between the driving roll and the supporting roll, a plurality of plate cylinders for transferring inks having a plurality of different colors onto the endless offset blanket, a plurality of first impression drums arranged to have the endless offset blanket held between the first impression drums and the plate cylinders, ink supply means for supplying the inks of the plural colors to the plate cylinders, and a second impression drum positioned to push the supporting roll and to have a printing medium held between the supporting roll and the second impression drum, the inks of the plural colors transferred onto the endless offset blanket being printed on the printing medium in a single operation.
In the present invention, a continuous pattern can be printed on a large and thick printing material by transferring images consisting of a plurality of different colors onto the same blanket.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of
Onuki Akio
Sonobe Saburo
Colilla Daniel J.
Kinyosha Co., Ltd.
Lackenbach Siegel Marzullo Aronson & Greenspan
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