CA2045580C - Nonreplicable document and method for making same - Google Patents

Abstract

A method and product resulting from application of the method for making the images in nonreplicable documents. Documents that cannot be replicated by known copying machines or other replicating devices are produced according to the invention method. All of the methods disclosed herein are instructive for making the images and art work on such documents by forming lines into various patterns in a manner imitative of intaglio or gravure printing. The pitch (d) of the document (30) lineations (32) is deliberately selected so as to vary minutely from the pitch (p) of the scanning trace (36) of various copying machines such as photocopiers, video opticons, and the like. The variation in pitch (d) may be obtained by deliberately manufacturing the document with the desired pitch or, subsequent to the image placement therein, altering the dimensions or geometry of the document so as to effectively alter its pitch parameter.

Description

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0 9~/08046 - 1 ~ P~r/ US90/0022 1 N5:~N~us~LIcABLE DOCUMENT ANI) ~ OI;~ FOR MA~IN(; SAME
BACKGROUND OF T~IE I~irVENTION
Field of the Invention This invention relates generally to bogus or counterfeit document detection methods and, parti.cularly to the method for printing or otherwise making a product document that will be nonreplicable by any sCAnn~ng-type copying device such as a copying machine, video opticon, and the like.
Discussion of the Prior Art Many methods have been employed, as well as myriad machines, in order to veriLy the authenticity of documents such as bank notes, checks, licenses and identification pictures. Currency, security and other valuable documents are, in most cases, printed or lithographed onto high quality media such as silk, rice paper or high content rag paper.
The printing may be black and white or color and most often employs one of two printing processes--- line intaglio or gravure (rotogravure). The first, intaglio, is a process widely used in the production of bank notes, securities, stamps and engra~ed documents. The distinctive sharpness of fine lines and readily discernable dif~erences in ink t~ickness that the process produces make it a preferred technique for production of bank notes and securities. The gravure pattern is similar to tha~ of intaylio with the ,~
exception being that rather th~ ine channels appearing between lines, the yravure etching consists of extremely small square - like cells laid out in a grid array. In both . . . . . . .
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of these methods of printing, the ink is helcl within the li~e troughs or square wells and transferred to the print media, under high mechanical pressures, by capillary movement. The gravure printing process is generally used for catalogs, magazines, newspaper supplements, cartoons, floor and wall coverings, textiles and plastics.
Other methods such as the Dultgen half tone intaglio process and the Henderson process (often referred to as direct trans~er or inverse half tone gravure) are o~ten used in place of the gravure but do not distinguish significantly over the previously described procasses relative to the grid-like orientation of lines and dots (formed when the square-type wells are used). Since the purpose of the instant invention is to provide methods and a product made from such methods for preventing replication of any important document, in black and white or color, the remaining portion of this dlisclosure shall concantrate more heavily on intaglio printed -surfaces rather than gravure or its variations. Further, most discussion will be confined to intaglio because a general disclosure relating to lin~ printing would necessarily include dot printing as well since, by the inventor's definition, a dot is merely a line of short length, its length being equivalent to its width. Thus, the sguare-type well or dot of he gravure printing process may be likened to the intaglio wh~r ~ two sets of parallel lines or lineations, one ortho~ to the other, are employed.

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~90/08046 PCr/~lS90/00271 After an intense, exhaustive search of the literature and patents on file at the United States Patent and Trademark Office, the instant inventor turned from the more current methods and machines for document verification and devised the instant invention product and the methodology for its preparation. The philisophical moti~ation for the instant invention is twofold: first, in order to determine whether a document is counterfeit, it is not necessary to determine its authenticity -- one only has to prove that a single element of the document is bogus; and second, a labored e~in~tion in order to determine a singular bogus element would be conducted best if the document were to contain within itself the means that would preYent its replication. In order to achieve these two objectives, it was necessary for the instant inventor to blend his skill in printing with the knowledge of optics that is readily available to one of ordinary skill. Accordingly, andi being long familiar with the phPnr enon of moire that often occurs in printing, he re~oned that what had always occured as a problem could be turned to the advantage of society in the elimination of the counterfeiting of face - value documents. For the edification of the reader it will suffice to say that the moire is a serious problem in color ~ep~uction. It is the occurance of an interference patte~n caused by the over printing of the screens in colo ~ tes ~sim1lar ef~ects can be observed by superimposing two pieces of a fine grid network such as-window screening). Indeed, the technigue of ' " ~ - .
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WO 90/0804fi P~VS~0/~)0221 2~5~80 rotating half tone screens, when making the negatives for aprinting plate, has been developed in order to avoid the moire interference. Often it appears as the geometrical desiyn that results when a set of straight or curved lines is superposed onto another set. If a grating design, made of parallel black and white bars of equal width, is superposed on an identical grating, moire fringes will appear as the crossing angle is varied from about one second of arc to about 45 degrees. The pattern will consist of equispaced parallel fringes; but, if two gratings of slightly different spacing are superposed, fringes will appear (known as "beat"
fringes) which shift positions much faster than does the displacment of one grating with respect to the other.
Finally, it has been noted that a different kind of moire pattern results when two families of curves of different colors are superposed --fringes of a third color are produced. IAn application o~ the use of the moire phPn snon is disclosed in U.S. Patent No. 3,109,239, issued to the instant inventor and titled SCREEN ANGLE INDICATOR~ This disclosure reveals a method that is used to locate, view and visually align the angle o~ half tone screens without the aid of magnification. The screen half tone which is to be read is placed over a screened 360 degree or 90 degree protractor which contains five half tone screens of about 60~ in value 2 1/2 degrees to the right and 2 ~/2 degrees to the left at angles of 45 degrees, 60 degrees, 75 de~rees, 90 degrees and 105 degrees. When the screen is turned within 5 degrees of a '. ' ~ ~ , : - . . . . .
' 2 ~ ~ ~ 3 ~0 YO90/0~046 Pc~/usso/oo22 predetermined angle, a moire interference pattern begins to visually form and, as the screen comes closer, a much darker and larger moire pattern becomes visible. When the screen reaches the exact angle to be located, the moire pattern appears greatly englarged and, in fact, turns either black or white. Any misalignment appears as an enlarged moire or secon~ry pattern; thus the screen an~le indicator crea~es magnified images by interference in order to identify and locate or position a half tone screen at a given angle. It became apparent to the instant inventor, therefore, that the moire pattern, rather than as an indicator which is gradually rPmoved from an image, may also be used as an indicator of some perhaps latent defect in a document. More appropriately, there had to be some way in which a patter~
could be included in an image by printing it in a selected pattern. Then, when the image was viewed through a superposed grid, such as previously disc~ssed, a moire pattern would be observed according to the degree in which the patterns interferred with each other. Moreover, if one were to reduce the moire apparatus to its simplest form, that is, such as viewing some backy,o~l~d through the common parallel-stake snow fence (suggested by the previous description of parallel black grid lines spaced by parallel white or clear areas of e~ual width), and if the pattern over which it i~ superposed is form ~ f lines and dots that are equally spaced ~rom each other (whether parallel or curvilinear), but a fraction off the pitch (or spacing) of : . , ., :

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- , - .: -WO 90/OB046 P~'F/US90/00721 the overlain grid, the observer would be deprived of a high percentage of the background field of vision. Thus, the background image, if formed of the line and dot printed grid, would be rendered nonreplicable to any apparatus being used to record the view. It is this part:icular aspect of ~oire pattern creation that is used by the instant inventor to create this invention. Further, he also recognized that because the modern copy machine, whether it be a standard color tone copier or a laser printer, scanned the imaye to be copied with a fixed-pitch scanning system, it was unnecesary to devise overlay grid means. In ~act, the modern replicator contains such a grid in the fixed - pitch, parallel scan format that is used to view the image to be replicated.
When apprised by friends, who dealt in the ~ieid of secure documents and negotiable instruments, that the advent of the color copier had almost overnight imbued the a~ateur counterfeiter with t~e ability to reproduce such documents as currency notes, travelers checks, and the like, it became readily apparent to the instant inventor that conventional means of document authentication would be insufficient to stop an almost exponential increase in the preparation of bogus documents. For example, with but minor skill and manipulation of con rols, a modern color copier, especially of the laser type, can make a mos~ credible reproduction of United States Bank Notes, trave ~ s checks, drivers' licenses and identification cards. So good are the replicas, that department store clerks, grocery clerks, bank tellers, change . ~ .

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090/08046 PCT/US90/002~1 machines, and a host of others have been duped by the introduction of these replicated documents into the market place. Major efforts o~ others attempt.ing to solve this problem at costs totaling seYeral mi:Llion dollars have all been unsuccessful. In particular, no-one hereto~ore has found a way to provide an original banknote or important document which embodies the two often-sought features of a copy-proof instru~ent; for example, one which to the unaided ~ eye is both indistinguishable from a prior (genuine) item and which is capable only o~ obviously bogus copier replication.

SUMMA~Y OF THE INVENTION
The problem posed by copier replication has been solved by this invention, which is based upon the serendipitous discovery and novel concepts described below. Consequently, it is now possible, for the first time, to produce legal tender paper currency, genuine travelers cheques, original postage stamps, government issued food StampS, important documents or certificates and the like, which to the naked eye are indentical to prior items of the same kind but, ln fact, have characteristics which reveal copier (especially color3 replications to be obvious countPxfeits.
The instant inventor in the course of sea~ching for a solution to this problem accidentally disco~ered that a color copie~ replication of an original.jtravelers cheque cannot .,~
itself be used to produce a cl~ly matching copy. Actually, it was found, surp:risingly, that no matter how the color copier was adjustefl to eliminate blemishes or defects .
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apparent to the casual observe~, the copies made from the first copy always had such prominent tell-tales, in on~ form or another.
On the basis of his knowledge and skill as an expert in the printing art and the science of optics, the instant inventor recognized that in this discovery he had the key to solving the copier replicatinq problem. Thus, he conceived the idea of using the bane of the printer to the advantage of the counterfeit preventor. ~e would use the moire effect to reveal the bogus color copy of a ~enuine banknote, for example, by producing the note image lineations in mismatch to the scanner of a color copier. The mismatch would be slight and not noticeable to the naked eye and thereby both basic requirements, which no one else was ever able to meet, could be totally satisfied. Moreover, the cost of producing such counterfeit-proof certificates need not be substantial.
The instant invention is there~ore conceived to counteract a specific illegal threat, withou~ having to resort to legislative acts which would in soms way hinder the technological growth and re~;n~ ~nt of the photocopy r~chi~e industry, and its most not~worthy products. It consists in a product, a ~ace-valued document (generally/ but not always printed1 that cannot be replicated by any known color copying system. The instant inventive method succinctly instructs the reader in both ways of prod~ ng the product and in a correlative method for dete~ in~ng whether a suspected document is a counterfeit that has been made fxom a noncopy-, .
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_g_ protected, authentic document which does not contain thenonreplicability factor inculcated by the present disclosure.
The basic method of counter~eit prot:ection teaches the inclusion of lines, dots and/or swirls embodied and integrally formed into art, pictures and other forms of images. The grid lines are made so as to differentiate minutely in vertical and/or horizont:al pitch from the linear grids employed by the scanning mechanisms of the machines used to replicate these black - white or colored documents.
Generically, such scanning replicators are typically black and white optical reproduction systems, such as office copiers, color copiers, and opticons that are used in conjunction with video systems. Subclassed in this generic group are the new and increasingly common, laser color and black and white optical reproduction systems. After creation of the authentic document, that is, one including the grid lines of predetermined pitch, the primary method of counterfeit protectlon, as well as the product thereof, have been realized. Any attempt at imitation or replication by means of a S~nni ng-type copier will result in the g~neration of inteference patterns and tones which are readily ernable (by the untrained and naked eye3 from the original ~or authentic~ document ln that the aesthetics of the do~ nt are distorted, omit~ed or otherwise completely destroyed in the replication. ~ erally; the dark tones of the authentic do~I ?~t will COpy darker, while the blurred or light to medium tones will copy lighter, whiter or completely - . .

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WO90/08046 2 ~ 1 o- YCT/US90/002~1 disappear. Any attempt by the counterfeiter to eliminate the . patterns and dlstortions in the replicated copy, by color correction or by angular movements of' the faulty replication, will result in intensifying the a~orementioned lightening and darkening effects; and it will cause secondary patterns, latently embedded in the original, to appear visible, thus rendering the replication or counterfeit as an obvious bogus document.
A corollary to the primary method for,making a non-replicable image is also inculcated ~y this disclosure. In cases where a counterfeit copy has been successfully made, say from an authentic document which has not been copy protected by the above mentioned method, and the method of replication has employed a scanning-type replicator or copy machine, the counterfeit document, no matter aesthetically pure it may appear to the naked eye, nonetheless contains included lines that already differentiatelminutely in vertical and/or horizontal pitch from the authentic document's print format. In other words, the counter eit copy now contains the seeds for its own deteetion if the instant inventor's correlatlve me~h~logy is then applied.
Such detection requires that the euspected counter~eit copy be first viewed and recorded by means o~ a sC~n~;~g and imaging device ~uch as,a copy -ch;ne, a television opticon, or the like; and after such reco ~ing, comparing an authentic species of the original document with the recording of the suspected counterfeit and detel i~; ny if the record of the . .. ,. :
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O9~/0~046 P~l/~S~0/00~21 suspected counterfeit reveals moire distortions relative to the authentic species. If so, the e~amining party will be able to confirm that the suspect document is indeed a counterfeit.
Regressing briefly to the "snow fence" effect ~that was m~ntioned in th~ Description of the Prior Art), an alternative method of employing the nnoire effect is also herein disclosed. A moire-distorted pattern is replic~ted quite readily if document imaging is realized by usiny a rather high number of lineations relative to the replicator scan line frequency. The notion here is that the "snow-fence" slats (i.e., the spaces between the replicator scan lines) obstruct more of the authentic image, thus distortin~
the replica. This i5 most noticable in color counterfeiting.
With the means taught herein, of producing a non-replicable document of the instant invention, as well as means for detecting a bogus copy of an authentic document not so protected, financial entities and government ins~ ntalities are now relieved from the potential counterfeit onus that was inadvertently placed upon them by the ad~ent o~ accurate and sophisticated replication ~yst~ms.
From the ~oregoing, and in ~iew o~ the detailed description set forth below~ it will be understood that ~his invention has both ~ethod and article of manufacture or product aspects. Further, in it~ method aspect this invention comprises the step of producing an electro-optically nonreplicable original certi~icate by providing on ~ . ., - ,. , - , . : .
, . . ~ , WO ~/08046 P~/U~9~/0~221 2 ~ 12-a matte a lineate pattern of visible image-defining lines which are of predetermined moire-producing pitch relative to an electro-optic copy machine scan protocol. Otherwise expressed, this method includes the preliminary step of dete~ ;ning the pitch of an electro-optic copy ~chine sc;lnner, In its article of manufacture or product aspect this invention then, likewise briefly stated, is an electro-optically nonreplicable original certificate which bears an image defined by a plurality of lines of predetermined moire-producing pitch relative to the scan lines or pattern of an electro-optic copy ~Chi ne .
Further defined in preferred embodiments this aspect of the inven~ion takes the form of a multicolor certificate such as a travelers cheque, banknote, food stamp, postage stamp, or other go~ernment or privat~ organization official issue.
As used herein and in the append~ claims th~ terms "general" "original" "legitimate" "legal" "legal tender"
"first run" and "authorized" meand and intend noncounterfeit issue. Also, the term "matte" designates or describes the paper cloth, parchment or other sheet material or tls~ue o~
which b~n4notes, traY~lers ~heques, po~tage stamps, o~ficial ~_ srts and certificates and the like are mad~.
RIEF D~S~TP~ION ~ T~ DRAWI~GS
Of the Drawings:
: Figure la is thé pattern of lines, dots and swirls of an intaglio or gravure print;

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2 ~ d /0 ~/080~6 PCT/US90/0~221 Figure 1b is a grid overlay;
Figure lc is the view of Figure la through the grid overlay of Figure lb;
Figure 2a is an intaglio print of horizontal, equidistantly spaced lines;
Figure 2b is the scann~ n~ pattern of a replicating machine;
Figure 2c is a mapping of Figure 2a produced by the ~can lines of Figure 2b;
Figure 3a is an illustration of the print pattern of a ~amiliar printed image;
Figure 3b is the moire skewing of the Figure 3a print pattern;
Figure 3c is a blurring or defocusing of the Figure 3b pattern in antioipation of reconstruction; and Figure 3d is the screened image of Figure 3c in preparation for reprinting.
DETAILED DESCRIPTION OF THE P~RED EMBODIMENT
By use of Figures la through 2c, the reader shall now be instructed in the method of producing the nonreplicable image o~ the instant invention.
Referri~g particularly to Figure la, there is depicted therein a typically printed pa~tern l0 consisting of various lines 12, dots 1~ and ~wirls 16. ;.7Those of ordinary ~kill will readily understand that s~cl an image may be printed in intaglio or gravure (more Ir_ ~ 1y rotogravure) and adaptations of these processes. Further, any process of .

Wo90/0~46 %~ ~5~?g~ -14- PCr/US90/0022l manufacture which represents vi~ible images by periodically spaced lines, dots or swirls, whether or not printed, (say included by fibre or stai~ patterns) will produce a product giving satisfactory moire results. Methods of etching, photo engraving and plate manufacture are beyond the scope of the instant disclosure and shall no lon5~er be referred to within this t~xt.
A grid overlay is revealed in Fiyure lb consisting of an a~ray of parallel, equally spaced black stripes oriented orthogonal to a similar pattern of black stripes 18. The grid of Figure lb is analogous to the earlier mentioned snow ~ fence pattern through which one might view a background image. When the Figuxe lb pattern is overlain the Figure la printed pattern, a distortion 20 in the Figure la pattern results as shown in Figure lc. The instant inventor defines the Figure lc pattern as a type of moire distortion pattern resul~ing from a mapping of the Figure la pattern by the function of the Figure lb grid overlay. Those of ordinary skill will also recognize that, were the function to be re~ersed, that is, if the grid lines 17', lg' o~ Figure lb . were ~o become the areas of image transmittal (rather than obstruction), and th~ areas denoted k to be areas of obstruction or opacityj the Figure lc map would depict the compliment of the illustration 20~actually show~. It can also be readily seen that the en~ire grid of Figure lb is not required in order to obtain the d2sired results of Figure lc.
The vertical portions 19 of the overlay grid a~e not . . .

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required; indeed, the relative easP by wh.ich a horizontal grid overlay may be realized in the scanning-type replicating r-chine (or instrument) lends itself wonderfully to its use in this invention. The solution o~ l:he problem to the counterfeiting of printed documents ]Lay in a form of reverse engineerin~ wherein the recognition of a yrid form of sC~nn~ ng in all replicating de~ices, and a knowledge of the moire effect, led the instant inventor to reason that a distorted image would result any time a grid-like scanning pattern failed to map any discrete part of an authentic ~ document into its replica. If, for example, the horizontal lines 17 of Figure lb were the nonscanned areas in a copy machine sCAnning protocol, and the interstitial or "see through" reas corresponded to the actual scanning lines, the illustration of Figure lc would in reality be the resultant replica or counterfeit. It can be readily seen that, to the naked eye, there might be very little distinction between the authentic and the co~nterfeit documents; however, if the Figure la print were arranged cleverly so as to ensure that the greater part of the image was not picked up by the .S~nni ng protocol, the resulti~g oopy would be highly distorted, full o~ moire interferenc~ pattexns and significant omission~. By this reasoning, the ~nstant inventor devised the invention which is now succintly described with the aid of Figur~ ~ 2a through 2c.
For the purposes of clarity, the pitch between printing lines and dots or between sc~nning lines of a replicating .

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WO90/080q6 PCT/US90/00~21 device shall be termed ~ in the case of the printing, and pin the case of the scanner. Turniny now to Figure 2a, there is depicted a typical intaglio printing 30, much like the printing of Figure la, but less stylized. The lines 32 axe separated by the pitch distance d; thus, they are parallel and equispaced. Figure 2b represents the sc~n~ing pattern 34 of a~y specifically identified replicatin~ device such as a color copying machine, laser scanner or television opticon.
Scanning on a very carefully controlled frequency, the scan lines 36 are parallel and have a constant pitch p. The very nexus of this invention demands that d be minutely more or less than p, say from half the scan line width up to 50% of p. With an appropriate choice of d incorpoxated into the printed image as exemplified in Figure 2a, the sc~nning of Figure 2b maps tXe printing into the replicated copy 38, shown in Figure 2c. At an arbitrary point where a scan line 36 is superposed directly on a print line 32, the replication 37 will be exact. However, thereafter and if the print pitch d is properly selected, there will be a greatly dj i ni shed frequency of overlap and the authentic pattern, to a great extent, will be lo~t. This is shown clearly in Figure 2c by the coincidence o~ print lines 32' and S~A~ning lines 36'.
It be~c e,s apparPnt to the reader what the writer m~ant by the above statement " d be minutely more or less thAn p", ~or the mapping essence of ~i~ur ~ 2c would be realized if d were less than p , instead of the indicated relationship shown in Figures 2a and 2b. The only dif~erence would be the - . ~ : -. . . . .

,JO90/0804S 2 ~ ll 5 ~ ~ ~cr/Us90/0o22l location of replica line 37, relative to the various pri~t lines 32' and scanner traces 36'. Replica line 37 would appear because, as shown in Figures 2a - 2c, scanner traces 36 would ~Isee~ only a smaller set (here for illustration, only one) onf print lines 32, thus transferring it only to the replica.
One of the most noteworthy attributes of the instant inYention is the inherent ability of the method and product to defy reconstruction of the authentic pattern. For example, those skilled in forms of decryption, that is reconstructing an authentic image by purposefully defocu~ing the lines and dots which form the composite image and then re~creening in preparation of a re-etchin~ would be ~rustrated in an attempt to retrieve an authentic document from the invention-skewed bogus copy. Referring to Figure 3a, there is shown an illustration 40 that app~ars on a f~miliar negotiable instrument that is not protected according to this invention. The detail 42 in Figure 3a is the representation of the pri~t pattern in oPe small portion of-the do~ ont. T ~i ately below this, at Figure 3b is the illustration 44 of what would be seen in thP same detail o~ a counterfeit protected document having a pattern typical of th~ instant inven~on used in its production. It may be readily discerned th~t the replicated pattern 46 bears strong resemblance to that shown in Fig~re 3a. In an attempt to . ~ , .
reproduce the pattern of 3a, the pattern in 3b is dellberately defocused or blurred 48 as depicted in Figure W090/08046 1'Cr/US90/00221 3c. After this blurring process, a counterf~liter would rescreen the image to prepare a new etched plate in order to reproduce an authentic looking dncument. Figure 3c illustrates the Figure 3b pattern as it would appear blurred.
Howe~er, were the counterfeiter now t:o screen the Figure 3c blurred pattern, the result would be the pattern 50 of Figure 3d. A cursory comparison of the Figure 3d 2attern 50 to the detail 42 of Figure 3a evidences the futility of such a technique, if applied to a document prepared according to the teachings of the instant invention. Generally speaking, the ~ Figure 3b rendering of the Figure 3a authentic document contains imaged areas that are anywhere from 35~ to 50%
reductions of the pristine image. Further, an attempt to replicate, on the offset press, the attempted reconstruction at Figure 3d will result in an image cont~in;ng an additional 50 to 75~ degradation in detail and hue.
To this point, the instant inventor has taught the invention in terms of varying the pitch distance between image lines so as to "detune" them or create a dissonance b~tween the print pattern in the document and the known ~reguency or pitch pattern of a sC~nning de~ice. That is not to say howe~er that an exacting print o~ such nature must always be had in order to embody the te~rhi~gs of the inYentor. A highly practical ~ethod is devised whereby the pitch in the printed document ma ~be arbitrarily varied, thereby acquiring the benefits of the instant invention.
This method is to simply change the ~; on~ion of lines and .
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O90/0804~ P~l'/U~90/002'1 ._19_ dots on a document so as to inherently vary the pitch between the various pattern elements. Accordinyly, the instant inventor suggests that, after a document of the type contemplated herein has been printed, the medium upon which it is printed be d~ en~ionally altered, generally by the application of heat. If performed on a suitable printing matte, the imprinted pattern will be subtly altered and the basic concept of the invention incorporated therein. It is recommended that a high quality, high rag content paper or a high quality rice paper such as is used in the printing of currency, be utilized.
The benefits of the aforementioned technique can be casually acquired by documents that are subjected to handling and indeed, those which have been counterfeited, especially since the toner application process of a color replicating device employs a matte-warping ~distorting) heat process of the typeldescribed above. A replication of such a distorted document, by either a color or black and white copier, or a scanning video opticon, will produce an image that ic literally full o~ moire distortions. Thus, it follows that if one attempts to copy or video scan a photocop~ counterfeit of an au~hentic document (color or black and white), the result i~ a severe moire - distorted image, because the heat of the counterfeiter's copier has distorted the copy matte, and thus the pitch of the authentic document's image lines, as taught by this disclosure.
Another metho~olo~ical corallary may be employed in ~, . ~' ' ' -: " , ' -. ' ~ ~' ' ~ , . ,...,, : :
.: . , WO ~/0~046 PCT/U~90/00221 ~ 20-cases where the scanning machine-replicator utilizes a scan line of greater than customary width. In such a situation, use of a document imaging process similar to that disclosed herein, but employing a much smaller lineation pitch (with a concr itant greater number of lineati.ons) is most efficacious. I~ the lineations exceecl 250 to the inch, the moire effect in the replica will be noticeable to the unaided eye, even with standard and unsophisticated copiers/replicators. This lineation frequency (250 lines/inch) is significantly higher than that used in the industry, today.
Myriad applications of the teachings in this disclosure are available to and may be made by those of ordinary skill and are limited only by the claims hereinafter appended.

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Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for making a copier counterfeit proof document comprising the steps of:
determining the locations of blind portions of a copier's scanning and copying pattern; and printing indicia onto the document so that said indicia will fall into said locations and thus be undetectable by said copier and result in a copy that is deficient in substantially all of said indicia printed onto said document.

2. A copier counterfeit proof document comprising indicia printed onto the document at a spatial frequency so as to fall principally within blind zones of said copier which blind zones are defined by the copying frequency of said copier.