Printing – Stenciling – Multicolor
Patent
1998-09-14
2000-08-29
Yan, Ren
Printing
Stenciling
Multicolor
101116, B41F 1504
Patent
active
061091723
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a screen printing machine comprising, for printing at least one first area in a defined color, an impression cylinder and a screen cylinder, and at least one second screen cylinder interacting with the same impression cylinder and being provided with means for printing at least one second area in a different color from that of the first area.
PRIOR ART
The use of screen printing machines comprising an impression cylinder and a screen cylinder for printing an area of a defined color is known. When it is desired to print juxtaposed or superimposed areas of another color, the first printing is dried and then the paper runs through a second machine comprising an impression cylinder and a screen cylinder for superimposed or juxtaposed printing of the second image in a color different from the first. Therefore in multicolor printing, there is one pass for each color after the ink of the previous printing has dried.
U.S. Pat. No. 3,934,502 discloses a screen printing machine comprising an impression cylinder and at least two screen cylinders interacting with the impression cylinder for the printing of at least two areas, each area being in a different color from that of the other.
U.S. Pat. No. 3,990,363 discloses a similar machine as the previous excepted that the printed areas are not superimposed and the second screen cylinder does not come into contact with the impression cylinder on the area printed by the screen cylinder.
With the concern to find means making security papers difficult to copy or counterfeit, various types of printing have been used on the same security paper including, inter alia, screen printing. Nevertheless, the printing of the various designs using different processes, and the intermediate drying which must take place, lengthen the time for printing the documents and problems of registration between the various printings make these printing operations tricky and increase the costs by the addition of equipment.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a machine for the screen printing of certain areas of a paper with at least two non-superimposed designs of different colors without having to run through an intermediate drying unit and using a relatively simple machine which is less voluminous than a multicolor screen printing plant used hitherto.
The screen printing machine according to the invention is organized so that the said second area is outside the first area, the second screen cylinder comprising at least one raised part on which a screen is arranged so the second screen cylinder does not come into contact with the impression cylinder on the area(s) printed by the first screen cylinder.
The advantages of the machine according to the invention are as follows: at least two non-superimposed areas in at least two different colors, which, on the one hand, makes intermediate drying between the two printings unnecessary and, on the other hand, results in a less voluminous machine, since only a single impression cylinder is used, and therefore a less expensive machine; printing images printed in succession by means of the same impression cylinder.
These results are, of course, obtained by virtue of the fact that the second area is printed by a screen cylinder provided with means for printing at least one second area of the paper which is not yet printed and does not touch the area already printed by the first screen cylinder. The means with which the second screen cylinder is provided comprise at least one raised part on which a screen is arranged. Thus, it is only the raised part or parts which come into contact with the impression cylinder on areas not printed by the first screen cylinder. Devices pushing the ink through the screen are provided inside the screen cylinder, these devices being preferably, but not exclusively, squeegees. The latter may be a conventional screen cylinder or, for example, like the one proposed in the applicant's European patent application No. 0723864. By avoidi
REFERENCES:
patent: 2445140 (1948-07-01), Hanington
patent: 3934502 (1976-01-01), Marino
patent: 3990363 (1976-11-01), Vertegaal
patent: 5247882 (1993-09-01), Zook et al.
De La Rue Giori S.A.
Yan Ren
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