Printing – Intaglio – Processes
Reexamination Certificate
2000-06-08
2001-12-11
Eickholt, Eugene (Department: 2854)
Printing
Intaglio
Processes
C101S181000, C101S182000, C101S219000, C101S225000, C101S247000
Reexamination Certificate
active
06327975
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a web-fed printing press having at least two printing units in a row for printing an image whose dimension in the longitudinal direction of the web is longer than the circumference of the plate cylinder of each unit. The invention also deals with a method of printing such images on the web without intervening blanks between the printed images.
Printing firms are sometimes requested by clients to produce printings as large as, say, from 70 inches (1778 millimeters) to 90 inches (2286 millimeters) in top-to-bottom dimension (i.e., dimension determined by the circumference of the printing cylinder, or dimension in the longitudinal direction of the web on which the printings are made). For offset printing of such large images, the most widespread conventional practice has been to prepare and keep in stock an assortment of outsize plate cylinders, as well as blanket cylinders to match, with a diameter of 23.6 inches (600 millimeters) and thereabouts, for various sizes of printings to be made. Such outsize cylinders have been interchangeably mounted to printing presses as the need arises.
This conventional practice is objectionable by reason of the outsize plate cylinders and blanket cylinders themselves and, of course, of the presses of matching size required by such cylinders. All such equipment demand inordinately high costs for manufacture, installation, operation, and storage.
Another known method involves the use of a relief or letterpress printing plate in the form of an endless belt running over a plate cylinder and a guide roller or rollers. The plate cylinder is, in fact, a sprocket having teeth for positive engagement in series of perforations formed in the side margins of the endless belt. The elongate image is imprinted from the belt on to the web running against an impression cylinder.
The relief printing belt does, however, possess the weakness of being not so satisfactory in the quality of printing as that by offset printing. The printings made by this prior art method is also unsatisfactory in positional accuracy as the plate takes the form of an endless belt and is driven by the sprocket. The service life of the printing belt is questionable, too, by reason of the presence of the perforations in its side margins.
The listed drawbacks of the two foregoing devices are altogether absent from a more advanced printing system according to Japanese Unexamined Patent Publication No. 63-189633. This patent application suggests use of two or more printing units in serial arrangement for printing on a web running successively therethrough. As the printing units prints different sections of an image at prescribed spacings on the web, the image sections provide in combination the image of any desired top-to-bottom dimension up to the sum of the circumferences of all the plate cylinders in use.
This third prior art approach, though definitely more favorable than the first two, has its own shortcomings. It had, first of all, limitations in the top-to-bottom dimension of the printings to be made. Since the plate cylinders of all the printings units were in constant rotation at the same peripheral speed as the running speed of the web, the spacings left unprinted by each printing unit were each equal to the circumference of each plate cylinder, or to an integral multiple thereof. The top-to-bottom dimension of each image thus printed, constituted of the sections printed by the respective units, was therefore limited to the total of the circumferences of all the plate cylinders if no blanks were to be left on the web.
If, on the other hand, images were to be printed whose top-to-bottom dimensions were less than the total of the circumferences of the plate cylinders, blanks were unavoidably created between the printed images on the web, each blank being equal to the difference between the total circumferential dimension of the plate cylinders and the image dimension in the longitudinal direction of the web. The blanks are nothing less than a waste of paper. Moreover, they necessitated the additional post-printing operations of cutting off the blanks and disposing of the cuttings.
SUMMARY OF THE INVENTION
The present invention has it as an object to produce printings of practically any desired top-to-bottom dimension on a continuous web of paper or the like without creation of intervening blanks.
Speaking generally, the invention is applicable to a variety of printing presses built on different operating principles typically including offset printing. In offset printing, as is well known, the inked image is first printed on a blanket cylinder, from which the image is offset or transferred to the web running against an impression cylinder. In most other types of printing presses, however, the image is printed directly from the plate cylinder to the web also running against an impression cylinder. Therefore, in the following summary of the invention and in the claims appended hereto, the term “printing cylinder” will be used to refer both to the blanket cylinder of offset printing and to the plate cylinder of other printing principles.
Briefly stated in one aspect thereof, the present invention concerns, in a web-fed rotary printing press, a method of printing elongate images on a continuous web of paper or like material. The method presupposes use of a first printing unit wherein a first printing cylinder coacts with a first impression cylinder for printing on the web a first image portion having a first dimension, in the longitudinal direction of the web, that is not more than the circumference of the first printing cylinder, and a second printing unit wherein a second printing cylinder coacts with a second impression cylinder for printing on the web a second image portion having a second dimension, in the longitudinal direction of the web, that is not more than the circumference of the second printing cylinder.
The first printing unit prints the first image portion on the web at prescribed spacings, by moving the first impression cylinder away from the first printing cylinder each time one first image portion is printed. The second printing unit prints the second image portion on the spacings left on the web by the first printing unit, also by moving the second impression cylinder away from the second printing cylinder each time one second image portion is printed.
Perhaps according to a most pronounced feature of the invention, the printing cylinder of each printing unit is rotated, while each time the associated impression cylinder is held away therefrom for creation of a space on the web, at a variable speed through an angle necessary for causing the first or the second printing portion to be printed at the required spacings.
Thus, each printing cylinder may be driven, when the impression cylinder is held away therefrom, faster or slower than when the impression cylinder is urged against the same via the web, and in relation to the traveling speed of the web. Such a variable speed rotation of the printing cylinder makes it possible for each printing unit to print the image portion at any desired spacings, which are to be, or have been, filled by the image portion printed by the other printing unit. Images can thus be printed on the web without intervening blanks. Being comprised of the first and the second image portion, each image can be of a greater dimension in the longitudinal web direction than the circumference of the printing cylinder of either printing unit, up to the sum of the circumferences of the printing cylinders of both printing units.
Another aspect of the invention concerns a printing press constructed for carrying the above summarized method into effect. All the necessary means according to the invention, including the variable speed motors for driving the printing cylinders, can be compactly and inexpensively built into a printing press of otherwise familiar construction.
The above and other objects, features and advantages of this invention and the manner of achieving them will become more apparent, and the
Eickholt Eugene
Miyakoshi Printing Macinery Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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