ARTICLE, PROTECTED AGAINST FORGERY USING A COLOUR COPIER BACKGROUND AND SUMMARY OF THE INVENTION Counterfeiting of important documents has become easier to do effectively with the development of sophisticated analog copiers, and digital reproduction equipment, such as digital copiers like the Canon 700, and digital scanners. Numerous attempts have been made over the years to develop security documents that are difficult, or impossible, to reproduce utilizing this sophisticated technology. Examples of such attempts that have been successful to one extent or the other are shown in U. S. patents 4,227,719 and 4,582,346. Another more recent attempt, designed specifically for digital reproduction equipment, is U. S. patent 5,772,249 which teaches using parallel straight lines having a modulation of the spacing between the lines according to a non-progressive modulation function, and with the width of the lines modified so that the ratio of the width of the stroke of a line to its spacing with the following line is equal to a particular constant ratio. The techniques discussed in the background of the 5,772,249 patent talk about security documents with non-parallel lines with a varying spacing and width, or parallel lines distorted with respect to the width and/or shape of a stroke. The actual execution of such security documents, even if successful, can be complicated.

According to the invention a security document is provided that is simple compared to the most recent efforts for avoiding successful copying utilizing digital reproduction equipment, such as digital copiers and scanners, yet is effective.

According to the present invention it has been found that when wavy lines are used that the lines may have a substantially uniform spacing and a substantially uniform width, yet when an attempt is made to scan or copy the document utilizing conventional analog or digital reproduction equipment, at least one of pixeling and discoloration occurs in the resulting document due to the moire effect [the moire effect is the creation of a geometric pattern that is a distortion of a true reproduction; in conventional printing it is often caused when two screened images are superimposed at certain angles, for example when making a half tone from a half tone image]. Thus by providing a simple pattern on all or part of the substrate (such as a paper document like a title, check, etc.) effective counterfeiting prevention or minimization can be provided.

According to one aspect of the present invention a security document is provided comprising: A substrate having a face. A pattern of substantially wavy lines having a subtantially uniform spacing between the substantially wavy lines, the pattern disposed on the substrate face on at least a portion thereof. And, the substantially wavy lines being configured and spaced so that upon analog or digital reproduction thereof at least one of pixeling and discoloration occurs in the resulting reproduction due to the moire effect.

In the security document, the substrate may be paper, plastic, or any other material that is printable and is typically used for security purposes. Also the substrate face typically has indicia imaged thereon which indicates that it is a bank check; bank note; stock certificate; title to real or personal property; marriage, birth, or death certificate; bond; or loan document, etc.

The wavy lines typically have a substantially uniform (within a line, and from line to line) width, and that width is typically between about. 0005-. 003 inches. The substantially uniform spacing between the substantially wavy lines is typically between about. 010-. 035 inches. In the preferred embodiment the substantially wavy lines are substantially continuous lines of ink or toner, but they may be made up of a series of dots, dashes, or like patterns.

Typically the substantially wavy lines have peaks and valleys of substantially uniform spacing, for example they may define substantially sinusoidal curves. The substantially uniform spacing between the peaks and valleys is typically about twice- twenty times the spacing between the substantially wavy lines. Also the substantially wavy lines may have a frequency of peaks and valleys that is about one-six inches, and a distance from the peak of one line to the next valley of that line of about. 05-one inches. Typically the at least one of pixeling and discoloration occurs at the peaks and valleys.

The pattern may be provided substantially only at a portion of the substrate face where there is indicia indicating that a signature should be applied. Alternatively the pattern may be over more than about 60% of the substrate face, e. g. even substantially the entire substrate face. In one embodiment some of the peaks and valleys are discontinuous portions of the substantially wavy lines that collectively provide indicia indicating unauthorized reproduction; and further comprising a background pattern on the substrate face at the discontinuous portions of the lines so as to substantially

camouflage the discontinuous nature thereof to the naked human eye in the security document before reproduction thereof.

The substantially wavy lines may be a color other than black or white, virtually any other color, and the pixeling and/or discoloration are even more pronounced where the lines are a color other than black or white.

According to another aspect of the present invention there is provided a method of producing a clearly denoted counterfeit document using a substrate having a face, comprising: (a) Imaging on at least a portion of the substrate face a pattern of substantially wavy lines having a substantially uniform spacing between the lines, and the lines having a substantially uniform width, so that upon analog or digital reproduction thereof at least one of pixeling and discoloration due to the moire effect results. And, (b) passing the substrate from (a) into an analog or digital reproduction device to create a counterfeit document having at least one of readily visible pixeling or discoloration.

In the method (a) may be practiced to produce substantially wavy lines having a substantially sinusoidal configuration with substantially regularly spaced peaks and valleys; and (a) and (b) may be practiced to produce at least one of pixeling or discoloration at the peaks and valleys. Also in the method, (a) may be practiced so that wherein some of the peaks and valleys are discontinuous portions of the substantially wavy lines so that the discontinuous portions collectively provide indicia indicating unauthorized reproduction upon the practice of (b); and further comprising (c) imaging a background pattern on the substrate face at the discontinuous portions of the lines so as to substantially camouflage the discontinuous nature thereof to the naked human eye in the security document before the practice of (b).

It is the primary object of the present invention to provide a simple yet effective technique for making it difficult to reproduce, without an indication of the counterfeit nature thereof, security documents even by utilizing digital reproduction equipment.

This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic perspective view of an exemplary embodiment of a security document according to the present invention;

FIGURE 2 is a schematic detail view of the relationship between a number of substantially wavy lines according to the present invention, greatly enlarged in size for clarity of illustration; FIGURE 3 is a view like that of FIGURE 2 only showing the lines with more pronounced peaks and valleys compared to the configuration of FIGURE 2, and showing what the lines look like after attempted reproduction on a digital copier; FIGURE 4 is a full size view of a portion of an embodiment of a security document according to the invention after digital copying thereof, showing the pronounced pixeling and/or discoloration at the peaks and valleys of the substantially wavy lines that occurs; and FIGURE 5 is a schematic enlarged detail view of a portion of another embodiment of a security document according to the invention where the substantially wavy lines forming the security aspects of the invention are configured so as to provide indicia of counterfeiting.

DETAILED DESCRIPTION OF THE DRAWINGS FIGURE 1 schematically illustrates an exemplary security document 10 practicing the present invention. The security document 10 comprises a substrate 11, such a piece of paper, imagable plastic, or the like, having a face 12 with indicia thereon. The indicia may include the name of the security document, such as the indicia 13, or like other indicia indicating what the security document 10 is. An incomplete list of the type of security documents, and the type of indicia 13, that may imaged on the face 12 include indicia indicating that the document 10 is a bank check; bank note; stock certificate; title to real or personal property; marriage, birth, or death certificate; bond; or loan document, etc. Any other suitable indicia, illustrated schematically at 14, such as a registration number, dates, values, company name, or the like, may be provided, and also a signature area with signature indicia, shown schematically at 15 in FIGURE 1, may be provided.

According to the present invention in order to minimize the possibility of effective reproduction of the document 10 it includes a security feature--illustrated schematically at 16 in FIGURE 1--a pattern of substantially wavy lines having a substantially uniform spacing between the lines. The pattern 16 is disposed on the face 12 on at least a portion thereof. In FIGURE 1 the pattern 16 is provided substantially

only at the portion of the document 10 having the signature indicia 15, but the pattern 16 may be provided at multiple places (either continuous or spaced from each other) on the substrate face 12, or may cover the majority, or more than 60%, of the face 12, including up to essentially the entire face 12.

FIGURE 2 is a greatly enlarged schematic representation of a part of the pattern 16 in which the wavy line 17 are more clearly visible. It should be understood, however, that in most security documents 10 the average person, using the naked eye, will not necessarily even be able to tell that there are wavy lines, but will just notice some sort of a pattern.

In the embodiment illustrated in FIGURE 2, the wavy lines 17 have peaks 18 and valleys 19 of substantially uniform spacing as indicated by the dimension 20, which corresponds to the frequency of the peaks 18. For example, as illustrated in FIGURE 2, the substantially wavy lines define substantially sinusoidal curves.

In the preferred embodiment according to the invention, the lines 17 have a substantially uniform width (for each line and from line to line) indicated by reference numeral 21 in FIGURE 2. That width 21 is typically between about. 0005-. 003 inches, for example about. 001 or. 002 inches. The substantially uniform spacing between the lines 17, is indicated by reference numeral 22 in FIGURE 2, is between about. 010-. 035 inches, e. g.. 02 inches,. 025 inches, or. 03 inches.

While the frequency 20, and the distance from one peak 18 to the next valley 19, indicated generally by reference numeral 23 in FIGURE 2, may vary widely, under most circumstances the frequency 20 will be about one-half to one inch, and the substantially uniform spacing 23 between the peaks and valleys 18,19 will be between about twice and twenty times the spacing between the substantially wavy lines, e. g. between about . 05-one inches.

In the preferred embodiment, the lines 17 are substantially continuous lines of ink or toner, but the lines--as indicated for the line 17'in FIGURE 2--may instead be made up of dots, dashes, or like elements.

The lines 17 may be a color other than black or white, such green, blue, etc. In fact when the lines 17 are of a color other than black or white the pixeling or discoloration effect upon analog or digital reproduction may be enhanced.

FIGURE 3 is a view generally like that of FIGURE 2 only showing a distance 23 that is larger compared to that in FIGURE 2, and showing the pattern after attempted digital reproduction. That is the pattern 117 in FIGURE 3 shows the lines 17 in

FIGURE 2 after the pixeling and/or discoloration has occurred as a result of attempted digital reproduction. In FIGURE 3 the pixeling and discoloration that occurs, which is a result of the moire effect, is indicated by the dark bands 118,119 which occur in the vicinity of the peaks and valleys 18,19 from FIGURE 2.

FIGURE 4 shows how the discoloration and/or pixeling is perceived at a distance by a normal naked human eye, very visible bands being provided where the pattern 16 once existed, and clearly indicating to even a casual observer that there is something wrong with the reproduction of the pattern 16, indicating a counterfeit. The pixeling or discoloration typically tends to form at the peaks and valleys although depending upon the reproduction device (e. g. copier or scanner) and/or the angle of the original document is placed on the device, the pixeling or discoloration may occur at other locations.

The pattern 16 illustrated in FIGURES 1 and 2 is particularly suitable for the signature area where there is signature indicia 15 for a security document 10, although it may be applied over the majority of, up to all, of the face 12. However under some circumstances, especially where the pattern is to be provided over a large area of the substrate 12, a hidden word or hidden words may be provided within the pattern at one or more locations, such as the words"Void","Copy","No","Counterfeit", a"no"symbol (@), etc. This may be done, as illustrated schematically in FIGURE 5, by providing some of the peaks and valleys as discontinuous portions of the lines 17, as illustrated for the pattern 216 in FIGURE 5. That is the peaks and valleys of some of the lines 17 --as well as some other portions thereof, perhaps--are interrupted so as to spell out-- in the schematic illustration provided in FIGURE 5--the word"NO", or like indicia indicating something wrong with the document if visible. Under these circumstances, it probably is necessary in most instances to image a background pattern on the substrate face 12 at the portions of the lines 117 that are discontinuous and spell out the word"NO"so as to substantially camouflage the discontinuous nature thereof to the naked human eye in the security document 10 before reproduction thereof. In the embodiment illustrated in FIGURE 5 this background pattern or camouflage is in the form of a plurality of dots or short lines, or other like patterns, 26 which are too small to be resolved by the reproduction device, or are reproduced in a different manner than the lines 17, so that when pixeling and/or discoloration occurs upon reproduction the word"NO"is clearly visible to the normal human naked eye. It should be understood that because of the complex nature of these shapes and configurations that it is not

possible to accurately reproduce them in a patent drawing, but those of ordinary skill in the art will understand the particular nature of the discontinuities.

It will thus be seen that according to the present invention a security document 10 may be provided which has the appearance of being a completely normal document before attempted reproduction thereof, but once it is passed into an analog or digital reproduction device, such as a Canon 700 color copier, or a comparable scanner, pixeling and/or discoloration results so that it is readily apparent to the naked human eye--as illustrated in FIGURE 4--that the document is a copy, or void words, or like indications of unauthorized reproduction appear, such as those that occur upon reproduction of the embodiment illustrated schematically in FIGURE 5. Thus in a simple way an effective security document may be provided.

It is to be understood that all narrower ranges within each of the broad ranges above is also specifically provided herein. For example (only). 010-. 035 inches means . 017-. 028,. 02-. 03,. 022-0.35, and all other narrower ranges within the broad range.

While the invention has been herein shown and described in what is presently conceived to be the most practical and preferred embodiment thereof it will be apparent to those of ordinary skill in the art that many modifications may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent products and methods.