WO1996038307A1

WO1996038307A1 - Films, printing forms and producing process thereof

Info

Publication number: WO1996038307A1
Application number: PCT/HU1995/000018
Authority: WO
Inventors: Tamás DÉTÁR; Tamás SZILÁGYI
Original assignee: Detar Tamas; Szilagyi Tamas
Priority date: 1995-05-30
Filing date: 1995-05-30
Publication date: 1996-12-05
Also published as: AU2573195A

Abstract

Subject of the invention is a process of making films and printing forms to be used for the manufacture of special prints, mainly securities. The subject of the invention is also the films and printing forms which are produced by the process of this invention. These are produced by forming a pattern on a carrier, then copying it by laser scanner and fixing it on film per colour, developing the film and making a print thereof, then making a sensitized printing form of the developed and controlled film. The process is characterized by producing, on a transilluminatable carrier, an optical grating as a special original, containing faults made deliberately and consisting of points with irregular contours and then by copying the so-produced optical grating with a laser scanner coded in the well-known way.

Description

FILMS, PRINTING FORMS AND PRODUCING PROCESS

THEREOF

Subject of the invention is a process of making films and printing forms to be used for the manufacture of special prints, mainly securities.

The subject of the invention also the films and printing forms which are produced by the process of this invention.

The production of securities usually involves the application of special typographical processes.

The development of typhographical technology and of photocopying on typographical level has enabled the production of coloured copies of banknotes or securities almost perfectly identical to the originals, which may give rise to absuses. Safety-papers with water-mark or containing special metal tlueads, with individual graphical elements, colour embossing or UV-generated paint and special perforations are to protect against the copying of securities.

Such special processes are expounded in the technical book: Nyomda az irόasztalon (Printing press on the writing desk) by T. Kolossa, T. Szilagyi, Editoprint, Budapest, 1990.

Typographical processes for the production of printing plates are well-known from technical literature.

One of the types of the printing processes is planography which includes offset printing. With this technology the graphical and non-graphical elements lie approximately in the same plane on the printing form.

Printing forms are made in the following steps. The first step is the formation of the text or figure and its recording on a magnetic plate or other carrier, such as film or paper.

The text or figure on the carrier is copied on a film by means of scanners, preferably laser scanners. The separated colour films are then developed, generally by means of an automatic developer.

The data are thus recorded on the films.

It is advisable to make control prints of the data recorded.

The above process is called cromalin process which has been elaborated by the Du Pont Company.

The process is usually repeated four times in accordance with to the colours used.

The ready review of the above steps can be found in the following technical books: Peter -Szilagyi: Ofszettechnolόgia (Offset technology) Teclinical Publishing

House, Budapest, 1978., pages 158-165, 165-170, 177-182/ and

Szilagyi: Korszeru Ofszettechnolόgia (Up-to-date offset technology). Editoprint,

Budapest, 1991., pages 1-62, 11 1-116, 121-123, 150-151.

A printing form is made of the controlled and approved films. The film is then put on a metal plate with a ligh-sensitive coating, preferably on an aluminium plate. It is lighted by a halogen lamp and the light-sensitive surface of the coating which has not suffered any change is then removed and the printing form fixed.

The processes known are desribed in detail in the books "Technologie des Offsetdrucks" (Verlag Beruf u. Schule, Itzehoe, 1989., S. 20-33, 76-82, 84-87,

95) and Werner: Standandisierte Mehrfarben Offsetdruck (Polygraph Verlag,

Frankfurt, 1982., S. 21-23). The aim of the above processes is to make a printing form by which prints close to the original can be prepared. Any number of identical copies can be made of these prints by photocopying.

The patent description EPO 273 526 describes a process for the production of security papers e.g. bonds, shares.

The essence of the process is that a so-called "moire" pattern is brought about by using superposed gratings shifted in relation to each other. Close copying of the moire is very difficult on ordinary photocopiers. The disadvantage of the process is that moire on the securities offers a disturbing sight, moreover it can be closely copied on special photocopiers, so it does not offer full protection against forgery.

We have set ourselves the aim to develop a process in which special films or printing forms are made, the prints from which cannot be made conform to the original if photocopied.

The essence of the process in the invention is that if we produce a special optical grating containing faults made deliberately and copy it with a laser scanner having a certain resolving capacity, we are able to produce a film and then a printing form, the prints made from which cannot be photocopied so as to be identical with the original.

The "optical grating" as generally known consist of elements with regular contours equally spaced between each other, for istance of points and point intervals.

Such an optical grating can be readily copied on carriers (e.g. films) by means of the electronic scanners used in our days since the copying of such "regular" optical gratings is effected by the help of a factory-made scanner program. If light is let through the points with regular contours of the regular grating, the light dispersion behind each grating point will be of equal intensity and direction, and so a pattern consisting of regular points will appear on the carrier, e.g. a film or sensitized plate.

When making a printing form from the film, and the prints with the printing forms, the regular grating pattern on the print is maintained and can be reproduced by photocopying.

Our invention, however, implies that - contraty to the above - an optical grating is produced in which the contours of the grating points are not regular (circular) but deformed, amorphous.

Moreover, the optical grating used in the invention contains also "faults" made deliberately, i.e. some of the points with amorphous contours are left out. So at these so-called faulty places the distances between the points and point intervals are unequal.

The essence of the present invention is that if a light beam is not let through a regular optical grating, but through an optical grating containing points with irregular contours and also faults, then the light dispersion behind these grating points will be of irregular intensity and direction.

This irregular dispersion causes a light interference behind the grating. The light beam altered through the interference produces then a pattern with an irregular layout on the carrier (film) positioned behind the grating. This irregular pattern, however, is an unstable grating, for it will desintegrate if relighted.

Lighting (e.g. in photocopying) actually causes a new interference and the paltem disintegrates in a different degree, so the copy will differ from the original print. Thus the patterns obtained from the fihns by printing with the help of printing forms as described in the invention cannot be counterfeited by photocopying, which makes them best suited for the production of bonds and various securities. Subject of the invention is therefore a process for tlie making of films and of printing forms tliat can be used for special prints, mainly for securities, by way of producing a pattern on the carrier, copying the pattern with a scanner and fixing each colour on a film, developing the film and making a print hereof, and then making a sensitized printing form of the developed and controlled film.

The process is characterized by producing, on a transilluminatable carrier, an optical grating as a special original, containing faults made deliberately and consisting of points with irregular contours, and then copying tlie so produced optical grating with a laser scanner coded in the well-known way. It is recommended to copy the special optical grating used in tl e invention by means of an argon-ion laser scanner of 2000-8000 dpi resolving power.

Tl e subject of the invention are also the films and printing forms which are produced by the process according to this invention.

The advantages of tlie process as described in the invention are the following: Securities can be made by an economic, simple process precluding copying. Owing to the wide range of possibilities for the location of faults made deliberately the number of variations of the "grating codes" recorded on films is almost indefinite.

The "grating codes" can be preserved if fixed on films and later they can be identified with certainty.

In the process described in the invention tl e points of tl e optical grating can be of any density, however, the size of the points must be larger than that of tlie separation pixel of tlie laser scanner.

In our process copying by laser scanner is done in a size no smaller than what is well discernible. We illustrate the process described in the invention with the following examples:

Example 1.

An opatical grating is brought about with 80 lines/cm grating density. 5 faults are located sporadically on tlie optical grating.

The optical grating is copied by means of an S-605 type Dainippon Screen argon-ion laser scanner with 7000 dpi separation in two machine revolutions.

A signal generator is connected to the scanner by means of which six laser beams draw a grating-point on the Fuji Is 5000 type film used. The repetition of the process is ruled out as the program adjusting switches of the appliance are in a position in which recording is not done in a regular, coded way but by chance.

The film is developed in a Dainippon F 305 type developer with the developing agents of tlie Fuji-Grandex system.

The special original produced in this way is copied on a film with the above scanner by coding in the known way, after wliich tlie film is developed according to the above.

A control print is made of tlie film developed using tl e Cromalin process of the

Du Pont Company.

The method used is to laminate the film by the help of tlie White Line Laminator equipment, then coat it with a toner by means of ATM V. paint duster and apply a closing foil of Top Coat Laminate brand, thus obtaining a sandwich structure which is then lighted by UV light.

The coat subjected to lighting is then removed from tl e sandwich structure.

A film is produced of each colour and these are then copied on each other for making the print.

The print is compared with the original and corrected if necessary.

The printing foπn is made from a 0,4 mm thick sensitized plate. The controlled film is placed on it and is lighted by a metal halogene lamp of 300-550 ran emission spectrum. The plate is developed in a water-alkaline developer, then rinsed and dried.

The printing form filled with paint is suitable for offset printing. ^• We print shares with the printing forms thus made.

On the surface of the shares the points of the optical grating can well be discerned with a magnifier.

The shares are put into a photocopier and photocopied for testing. When examining the copy with a magnifier it can be established tliat tlie copy does not contain the grating points visible on the original share.

Example 2. We proceed in every respect according to point 1. but use 8000 dpi separation for the argon-ion laser scanner.

Claims

What is claimed:

1. Process for making films and printing forms used for the production of special prints, mainly securities by foπning a pattern on a carrier, then copying it by laser scanner and fixing it on film per colour, developing the film and making a print thereof, then making a sensitized printing foπn of tlie developed and controlled film, characterized by producing, on a transilluminatable carrier, an optical grating as a special original, containing faults made deliberately and consistmg of points with irregular contours and then by copying the so produced optical grating with a laser scanner coded in the well-known way.

2. Process according to claim 1. characterized by copying with an argon-ion laser scanner of 2000-8000 dpi resolving power.

3. Films and printing forms characterized that they are produced by tlie process according to claim 1.