JP2002536202A - Substrate for printing - Google Patents

Abstract

A substrate for a security document such as a banknote, has physically formed therein identification features which are invisible to the eye but are repetitive so as to be detectable, after scanning, by computer. The features may be arranged in a 2D matrix and be spaced at regular intervals over the substrate. The physical features may be formed by embossing, surface treatment of lacquered papers, impregnation, laser treatment or watermarking. The features enable banknote verification and determination of denomination. Reproduction of the document by printing may be inhibited by subjecting the image data signals to an algorithm which serves as a second control to downgrade or inhibit reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION

The present invention relates to a substrate, mainly paper, and more particularly to a method of modifying a substrate to be suitable for use in printing security documents.

[0002]

BACKGROUND OF THE INVENTION

It is known to scan a document to be printed and convert the image into digital data for supply to a computer. Using this digital image data, a copy of the original document can be printed using a laser jet or inkjet printer, in which case an imaging device (usually a scanner)
, Computers and printers act as copiers. By editing or manipulating the stored data using graphics software, the final print can be a very accurate reproduction of the original. In addition, this data can be sent to a remote location, e.g., via the Internet or by modem and telephone lines, or stored on a disk or other memory device for future use; May be used to forge security documents such as ID cards and the like.

[0003]

[Prior art]

Methods are known for altering a substrate so that a real substrate can be identified and distinguished from a counterfeit substrate. Typically, these methods involve marking a real substrate with a material that fluoresces under ultraviolet light or emits light only in certain regions of the visible spectrum, or includes a magnetic material or infrared absorbing dye. Or including a large watermark in the form of a picture or barcode on or in the substrate.
All of these methods involve significant changes in the substrate (such as a watermarking method) or special materials that usually require a special detector to determine if the substrate of any document is genuine. Needs to be included. Such methods tend to be expensive, and the effects are usually easily visible to the naked eye, and it is not impossible to change paper and other substrates in a similar manner to disrupt the verification process.

[0004]

[Object of the invention]

One object of the present invention is to provide a special substrate on which a security document can be printed that has features that are not reproduced on a photocopier but can be detected using a computer or other data processor-based imaging system. is there. However, since the computer system or copier can be arranged to reject processing of the image upon detection of the feature, the feature is typically provided with an unprotected copy of the image data signal obtained from such a system. It will not be played by a machine or printer.

[0005]

Summary of the Invention

According to one aspect of the present invention, the substrate on which the security document is printed includes a plurality of physical features on its surface, the features generating an image data signal at the output of the optoelectronic device when illuminated and imaged. The substrate is further characterized by the following.

[0006] 1. By selecting the contrast between the feature and the rest of the substrate surface, the image data signal corresponding to that feature is substantially derived from the image data signal relating to the rest of the substrate surface and / or the background noise signal at the output of the optoelectronic device. Make it indistinguishable, and thus invisible to the naked eye,
Further 2. This feature is repeated at least over a portion of the surface area of the substrate such that the time or position of the signal for each feature has at least one fixed relationship to the signal for the other of said features. Whereby the computer device to which the image data signal is supplied can be programmed to identify whether said at least one fixed relationship feature signal is present in the data, Can help with identification.

This feature may be repeated at regular intervals. Each of the physical features may have similar properties as each of the other features on the surface.

[0008] The same type of document may be printed on a substrate having similar features having a similar fixed relationship across the surface of the substrate. Thus, for example, one type of banknote may be printed on a substrate having a particular type of surface features and one or more particular spacings.

The spacing may be chosen to be constant in one direction only, or to vary according to a special known pattern.

[0010] Similar or different regular intervals may be selected for features in another direction having a particular spatial relationship with respect to the first direction, eg, perpendicular to the first direction.

In a preferred example, the features are arranged in a 2D matrix on the substrate surface. The presence of such features on the substrate surface constitutes a first sign of the substrate, whereby the substrates can be distinguished from a substrate that does not contain said features or can be distinguished from one another depending on the choice of features.

The second sign of the substrate may be achieved by introducing changes to the matrix, such as by removing features from specific locations in such a regular matrix.

[0013] For example, all fourth features along each of the third lines may be omitted. Preferably, the security document is encoded using both the first and second codes.

[0014] Additionally or alternatively, a second code may be provided when the matrix is formed from features having two unique properties, instead of omitting features at specific locations in the matrix. , One type of feature is placed at one set of locations in the matrix, and the other type of feature is placed at another location in the matrix. In a simple example, the set of features may be generally circular, and the scattered features that generate the second code may have different shapes that are easily distinguishable, such as rectangles or triangles. .

The sign of the substrate may be selected by selecting the spacing between features, or by selecting features having particular characteristics, such as identifiable shapes in the image data signal associated therewith, and / or such features may be Replacing the first property at selected points of the regularly occurring matrix with other features having a second different property;
There are almost a myriad of possible combinations and permutations available to encode a security document substrate, as can be achieved by omitting features at certain points in the matrix.

Thus, the present invention not only allows a reliable method for the identification of security documents to easily detect counterfeits which are not printed on a suitable substrate, but also, for example, different types of security documents. Banknotes, checks from different banks,
Each of the individual types of security documents, such as passports issued by different establishments, and the like, may be provided, if desired, with a particular first and / or second selected for the substrate on which they are printed. It can be uniquely identified by a code.

Image analysis to identify regular patterns and / or dropouts in regular patterns, and / or the presence of detectable feature shapes or other visually distinguishable features in an image Techniques are readily available and known, and image data can be checked and verified by using high-speed processors such as DSPs and the like, or can be done virtually instantaneously when scanning documents.

Preferably, the selection of the physical features for encoding the surface of the substrate provides a first code that does not appear in the electrostatic image of the photocopier. This means
Attempts to duplicate the original by photocopying ensure that only copies containing the printed content of the document are produced, unless the substrate on which the original is duplicated contains the correct physical symbols on its surface.

When a second code is present, any change in the first code that makes up the second code can be distinguished by the naked eye or picked up by a photosensitive device such as used in photocopiers. More preferably, it is difficult.

Preferably, the physical feature code is in the form of a repeating pattern. This identification feature does not affect or aesthetically impair the appearance of the security document (e.g., banknotes), so in the case of banknotes, existing identification printed on an uncoded substrate It is permissible to introduce new banknotes provided on the substrate according to the invention together with the banknotes. Because, if the general appearance of the document is invariant to the naked eye, old but authenticated banknotes that do not include the physical feature codes on the substrate surface provided by the present invention were printed on the encoded substrate This is because it looks like a banknote.

Examples of physical feature codes of a substrate as described above include embossing with an inkless intaglio, or embossing a surface with a calendar during the manufacture of the substrate.

In any substrate, two or more different encoding techniques may be combined.

According to the present invention, a security document is printed on a surface of a substrate for printing the security document.
The second pattern is recessed and / or grooved according to the first pattern encoded therein, whereby the image data signal obtained by scanning the document is subjected to the first mathematical algorithm by a suitable mathematical algorithm. The object is to make a security document printed on such a substrate identifiable by determining whether a second pattern can be found in the image data signal associated with the pattern.

The pattern may be encoded to generate multiple repetitions of the code on the substrate.

The encoded pattern may not extend over the entire surface of the substrate forming each document, but may only extend over selected areas aligned with a particular printed area of the substrate, and According to another aspect, the print area is selected to facilitate detection of changes in the substrate surface during scanning and conversion of the image to an image data signal.

Redundancy caused by multiple iterations can be advantageously used because multiple similar iterations increase the detectability of the code by increasing the effective signal-to-noise ratio. This, in combination with the selection of a particular area of the printed area of the final document upon which the repetition is placed, facilitates the data processor detecting the presence of a substantially invisible pattern in the data signal resulting from the scan.

In order for the document identification system to work, the signature of the document is specified, for example, by optically scanning the document to produce a computer-handleable image data signal, or specialized imaging and image analysis to perform this function. It must be readable by using the device.

[0028] The invention also resides in a security document substrate adapted to be identifiable, such as by having a detectable surface feature therein for enabling such identification.

The invention also resides in a security document when printed on a substrate as described above.

A first application of the invention is in the production of security documents to prevent or degrade the reproduction of such security documents using a scanning process that converts the images into image data signals for controlling the printing process. In treating the surface of the substrate as described above for use, a second control is introduced when the surface code is detected by subjecting the image data signal to an appropriate algorithm, and the second control is a printing control. By reducing or preventing the quality of the process, a copy of the original document or its good quality is prevented.

A second application of the invention resides in a document verification method by scanning a document and converting optical information into electrical signals using a photosensitive device, wherein one or more are used for recognition purposes. A data processor is programmed to look for information in the electronic signal that encodes the further surface and generates a confirmation signal to verify the document when it is detected in image data obtained from imaging and scanning the document And vice versa.

The present invention may also be used to validate a document by checking that one or more patterns of one or more particular features are present in the document, the computer-based document. A scanning device is provided.

Thus, for example, banknote validators associated with cash boxes at stores, banks and post offices can be provided at relatively low cost, and it is possible to verify the publicly offered banknotes at the point of transaction before receiving them. .

In the case of currency notes, determining which type it is may be of further interest, and when more than one source organization is involved, which organization is It may be advantageous to determine whether a bill has been issued. This type of computer-based document checking function can be used as a bill acceptor, can be used in a bill changer, and can be used by a blind person to find out which bank note he owns. it can.

[0035]

[Description of different encoding techniques]

Surface treatment of a substrate according to the present invention includes any technique for visualizing lighter and darker areas on the surface of a processed sheet of a substrate when illuminated for scanning.

[0036] Either or both of the first and second codes may be in the form of a repetitive pattern that is distinguishable under appropriate lighting to provide detectable content in the digital signal obtained by scanning. You may.

[0037] (1) embossing in the first technique of carrying out the present invention, the substrate may be embossed during its manufacture. This is typically done in the production of paper or sheet plastic by a process known as a calender, which passes through a high pressure nip between two steel rollers in order to smooth the material sufficiently for printing. By forming a depression in one or both of these rollers, the paper or plastic substrate is pressed in between, forming an embossing pattern corresponding to the depression. By suitably encoding the embossed features, the substrate is encoded as required in the present invention and can be detected by suitable illumination and converted to a digital data signal by a scanner for analysis by a data processor. Become like

(2) Surface Treatment of Lacquer Paper When a resin or lacquer or other material is mixed with paper or plastic substrate material to provide a smooth surface for printing, the actual surface of the substrate has a security document on it. The encoded structure is smooth enough to accept printing ink to make it printable, but also includes fine patterns in less smooth areas that would be less likely to accept printing ink. Can be formed on the surface.

(3) In order to impregnate with a fluid such as an impregnating resin or a lacquer, a selected region of the substrate exhibits a repetitive pattern, and the optical absorption or reflectance characteristic or the optical density of the substrate is sufficiently changed. The surface may be modified by a technique that makes it possible to distinguish between impregnated and non-impregnated areas under incident light during scanning for digitization.

(4) Printing is performed by etching the surface of the laser processing substrate with a laser beam (
Or await the printing) on the surface. This technique lends itself to the creation of very fine patterns on the surface of the substrate, and the laser beam can be adjusted very precisely so that, with or instead of the spacing edge or thickness, or instead, the depth of any such grooves or cavities. Can be used to introduce the adjustment of the height.

(5) Watermarking Watermarking changes the thickness and / or texture of a substrate, which changes can be made visible under incident light to form the first and / or second codes of the present invention. Can be used. This can be formed in two ways.

In the method of producing a fourdrinier paper, when forming it, a wet paper is embossed using an embossing roller, whereby a mark corresponding to the embossing is stamped on the paper. By forming the embossments in a suitable repeating pattern extending over the area of the web, the paper can be encoded with a watermark pattern.

A second technique for forming a watermark uses a so-called cylinder molding method. In this method, a watermark is formed by a cylindrical wire mesh engraved with "molding" in the form of an image. Increase or decrease the amount of fiber on the mesh mound during paper manufacture, where the thicker paper gives a darker effect when seen in transmission, and thinner areas are seen in transmission Sometimes thinner. However, since both types of watermarks are only visible in the incident light, this can be used to provide the background code required by the present invention.

According to the present invention, a pattern may be applied to the surface of a substrate, especially a paper substrate, using any of the watermarking techniques, which pattern is substantially insensitive to the naked eye,
It is shown as a low contrast pattern when exposed to incident light as the document is positioned for scanning and digitization.

The techniques described so far provide a surface-encoded substrate that can then be printed to form a security document. However, some coding techniques, such as embossing, may be applied after some or all of the document has been printed.

For example, embossing may be applied after the title or other text, or in the case of an ID document, for example, personal data is printed on a flat substrate, and the surface code is formed as a post-print step. You.

Embossing encoding can be achieved while printing at least some areas of the document. Thus, surface encoding may be provided to the document by so-called "blind" intaglio printing or intaglio printing with colorless ink. In such a method, the image is printed using a plate containing the engraved areas, some of the engraved areas are filled with ink, and some are left empty in the case of blind intaglio printing. The ink is transferred to the substrate by pressing the appropriately inked engraving plate against the substrate under high pressure. The substrate may be embossed with the engraved image under applied pressure, and some of the substrate surface may be printed and other portions may simply be embossed.

[0048]

[Explanation of the embodiment]

The process for physically forming the identifying features on the substrate of the manufacturing banknote (or other security document), in this case embossing, will be apparent from FIG. 3 without further explanation.

The resulting substrate is shown in FIG. 1, where in fact the identifying features, in this case the repeating barcode pattern, are invisible to the naked eye.

The banknotes are conventionally printed on a substrate and the results are shown in FIG. In practice, the discriminating feature is invisible to the naked eye, so it does not detract from aesthetics and does not affect the design freedom of the banknote image. It is noted that the banknote design may be printed either before or after the identifying features are physically formed in this case by embossing (FIG. 3).

The detection computer-based device can detect the aforementioned signature in various ways, two of which are described below.

An encoded document is converted to digital form when scanned by a computer. This typically means that the image is analyzed into red, green and blue channels for each pixel or pixel. Pixel colors are assigned values on a scale of 0 to 255 (8 bits) in each of their channels, typically with maximum brightness assigned to the value 255 and “colorless” assigned to the value 0. That is, bright white is represented by all three channels having the value 255, and black is represented by zero intensity having the value 0.

When a real image, such as a printed banknote, is scanned into the system, most pixel values are located in the central area, eg, between 230 for the paper background and 40 for the darkest print. The pixels associated with the embossed code are affected by the shadows from the embossment created by the illumination at the detector. Generally they are in a band close to the paper background value.

For example, if the embossing is shallow, the shadow is light and lies mainly within a band of 20 gray scale values relative to the paper background value.

All values between a value slightly lower than the paper value (eg 228 in this example) and the lowest value for the coding band (eg 210 in this example) are set to 10 or 0. Reset to the value (almost black) and 21 in this example.
Resetting all other values between 0 and 0 to 230 (in other words, the same color as the paper background) is easy for computer programs.

This procedure is usually very small, because it is not easily seen, and all printed and unmarked features, except for signs and very weak features associated with the design, which are not included in the design for aesthetic reasons. It has the effect of eliminating the design features. This procedure turns the embossed code itself black (see FIG. 4), which can be read by programs specially designed to recognize this code. As a simple example, when the code is a series of alphanumeric characters, such as letters and numbers, the data can be read using an optical property recognition program to determine whether it is a known code. Alternately, more sophisticated image detection techniques may be used, especially when the codes are of a more complex type, such as those used for digital watermarking. In some cases, it may be preferable to show only the sign (FIG. 5).

Alternatively, the embossed code can be extracted using a contrast enhancement routine such as that commonly known as “equalization”. This is shown in FIG. This type of routine sets the maximum value of pixels in each channel to 255, sets the minimum value to 0, and attempts to redistribute pixel values between the two evenly. This has the effect that the difference between the pixel value close to the paper background and the pixel value for the code increases, making it easier to recognize in an image recognition program or routine. This method has the disadvantage that the identification routine has to ignore any other design features that are not relevant to the code.

However, more sophisticated routines that recognize complex code patterns, such as those used for high-level code in complex images and patterns, may be used.

[Brief description of the drawings]

FIG. 1 illustrates a banknote substrate physically formed with bar code features that are in fact invisible to the naked eye.

FIG. 2 is a diagram showing a banknote image printed on a substrate.

FIG. 3 is a flowchart of a process for embossing barcode features on a substrate.

FIG. 4 is a diagram showing an image of a banknote represented by a computer code extraction routine.

FIG. 5 is a diagram showing an image of a banknote represented by a computer code extraction routine.

FIG. 6 is a flowchart illustrating one of the possible detection routines.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] December 8, 2000 (2000.12.8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Contents of correction]

[0005]

According to the present invention, a substrate on which a security document is printed includes a plurality of identifying features on its surface, the features generating a data signal at the output of the optoelectronic device when illuminated and imaged by scanning. This substrate is further characterized by the following.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Contents of correction]

(1) The contrast between the discriminating feature and the residue on the substrate surface is determined by converting the image data signal corresponding to the feature into an image data signal relating to the residue on the substrate surface and / or a background noise signal at the output of the optoelectronic device. And (2) repeating the feature at intervals over at least a portion of the surface area of the substrate, Programming the computer device to which the image data signal is supplied, such that, upon confirmation, the time or position signal for each feature has at least one fixed relationship to the signal for the other of said features. The at least one characteristic signal having a fixed relationship is You can identify whether present in over data may help identify the imaged document.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] March 17, 2001 (2001.3.1.17)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72 ) Inventor Stone, Robert George United States, 21042-4802, Maryland, Elliott City, Burnside Drive, 10214 F term (reference) 2H113 AA03 BB02 CA39 CA40 FA56 3E041 AA01 AA02 BA09 BB03

Claims (26)

[Claims] 1. A substrate on which a security document is printed, the surface of which comprises a plurality of physical features, said features generating an image data signal at the output of the optoelectronic device when illuminated and imaged. B.) Selecting a contrast between the feature and the rest of the substrate surface such that the image data signal corresponding to the feature is substantially derived from the image data signal relating to the rest of the substrate surface and / or the background noise signal at the output of the optoelectronic device (Ii) repeating the features at intervals over at least a portion of the surface area of the substrate so that the time or position of the signal for each feature is At least one fixed relation to the signal about the other of The computer device to which the image data signal is supplied so as to be able to identify whether said at least one fixed relationship characteristic signal is present in said data, and to identify the imaged document A substrate, which can help. 2. The substrate according to claim 1, wherein said identification features are repeated at regular intervals. 3. The substrate of claim 1, wherein each of the physical features has similar properties to each of the other features on the surface. 4. The spacing of the discriminating features is selected to be constant in only one direction or to be varied according to a special known pattern, for example perpendicular to said first direction, The substrate according to any of the preceding claims, wherein similar or different regular spacings are selected for features in another direction having a particular spatial relationship with respect to the first direction. 5. The substrate according to claim 1, wherein the features are arranged in a 2D matrix on the substrate surface. 6. The substrate of claim 5, wherein the second sign of the substrate is achieved by introducing a change in the matrix, such as by omitting features from specific locations in the regular matrix. 7. The matrix is formed from features having two distinctive characteristics, one type of feature being located at a set of locations in the matrix and the other type being located at another location in the matrix. The substrate according to claim 5, wherein the substrate is provided. 8. The method according to claim 1, further comprising selecting a physical feature for encoding a surface of the substrate to provide a first code that does not appear in the electrostatic image of the photocopier. The substrate as described. 9. The substrate according to claim 8, wherein the physical characteristic code is in the form of a repeating pattern. 10. The physical feature code of the substrate includes embossing with an ink-free intaglio or embossing the surface with a calendar during manufacture of the substrate.
The substrate according to claim 1. 11. The substrate according to claim 1, wherein two or more different encoding techniques are combined in any substrate. 12. The identification feature is formed by making a depression and / or groove on a surface of a substrate for printing a security document according to the first pattern in which the second pattern is encoded. Scanning the document and applying an appropriate mathematical algorithm to the resulting image data signal to determine if a second pattern can be found in the image data signal associated with the first pattern. The substrate of claim 11, wherein the printed security document is identifiable. 13. The substrate according to claim 1, wherein the pattern is encoded to generate a plurality of repetitions of a code on the substrate. 14. The substrate according to claim 1, wherein the encoded pattern extends over a selected area that is aligned with a particular printed area of the substrate. 15. The printing area is selected to facilitate detection of substrate surface changes during scanning and conversion of an image to an image data signal.
5. The substrate according to 4. 16. The method according to claim 1, comprising any lighter and darker areas that are invisible to the naked eye, but are visible on the surface of the processed sheet of the substrate when illuminated for scanning. A substrate which has been subjected to a surface treatment according to item 1. 17. The substrate of claim 16, wherein the substrate is embossed during manufacturing to form an identifying feature. 18. A paper or plastic substrate material mixed with a resin or lacquer or other material to provide a smooth surface for printing, and the actual surface of the substrate printed thereon to enable printing of security documents. 17. The surface of claim 16, wherein an encoded structure is formed on the surface that is sufficiently smooth to receive ink, but also includes a fine pattern of less smooth areas that are less receptive to printing ink. Board. 19. In order for selected areas of the substrate to exhibit a repeated identification pattern by being impregnated with a fluid such as resin or lacquer, the optical absorption or reflectivity properties or optical density of the substrate can be modified sufficiently. The substrate surface is modified by such a technique that the area impregnated and the area not impregnated under incident light can be distinguished,
The substrate according to claim 16. 20. The substrate according to claim 16, wherein the surface is etched by the laser beam to create cavities or grooves in the surface to be printed (or to wait for printing). 21. A watermark is used to change the thickness and / or texture of the substrate, which change can be visualized under incident light and used to form the first and / or second codes. The substrate according to claim 16. 22. A security document substrate adapted to be identifiable by having detectable surface features therein according to any of claims 1 to 21 to enable such identification. 23. A security document printed on a substrate according to claim 1. Description: 24. A substrate on which a security document is printed, using a scanning process to convert the image into an image data signal for control of the printing process by surface treating for use in manufacturing the security document. A second control is introduced when surface codes are detected by preventing or degrading the duplication of such security documents and subjecting the image data signal to an appropriate algorithm, which reduces the quality of the printing process. Or a substrate that prevents or prevents this from replicating the original document, or at least its good quality. 25. A document verification method by scanning a document and converting optical information into an electrical signal using a photosensitive device, wherein a surface invisible to the naked eye in the electronic signal is used for recognition purposes. A data processor is programmed to look for encoded information and generates a confirmation signal to verify the document when said information is detected in image data obtained from imaging and scanning of the document, and vice versa. Method. 26. A computer-based adapted to verify a document by checking that one or more patterns of one or more particular features that are invisible to the naked eye are present in the document. Document scanning device.