Counterfeit Deterrent Features for the Next-Generation Currency Design (1993) / Chapter Skim
Currently Skimming:
4 Description and Assessment of Deterrent Features
4 Description and Assessment of Deterrent Features
Pages 39-86
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 39... ...
The last section is a summary of the recommendations. Discussion of two types of visible deterrent features is contained within this chapter: passive and active.
|
From page 40... ...
Many of the counterfeits are detected at points of transaction by having a wrong "feel." This distinctive paper, in combination with intaglio printing, provides significant counterfeit deterrence at a moderate cost. The BEP requires strict control of currency paper to ensure that it is not available to potential counterfeiters.
|
From page 41... ...
For example, the high pressure applied to the ink when the printing plates are pressed against the paper during intaglio printing forces ink into the spaces between the paper fibers, beyond the edges of printed lines. In letterpress printing, the pressure between the plate and the paper tends to squeeze ink to the edges of the raised characters, leaving an obviously thicker layer of ink along the boundaries.
|
From page 43... ...
However, the intaglio printing equipment employed by the BEP has several limitations that prevent some potential deterrent features from being incorporated. For instance, those counterfeit-deterrence features that depend on accurate registration of printed features between the front and back sides of the note would not be possible to produce on the existing intaglio equipment, even assuming ideal conditions.
|
From page 44... ...
The Federal Reserve banks are designated by a letter and a corresponding numeral. The first character of the serial number is a letter that designates the Federal Reserve Bank and matches the letter in the Federal reserve seal.
|
From page 45... ...
The microprint is at the limit of resolution of the intaglio printing process; therefore, it will not be possible to use intaglio microprint to deter reproduction by higher-resolution copiers and printers. Color The light-green tint of authentic currency paper is difficult to reproduce and is one feature distinguishing this paper from commonly available paper.
|
From page 46... ...
An assessment of the generic types of substrate-based features follows. Laminated Substrates The ability to produce currency paper by joining two half-thickness sheets with or without a very thin plastic interleaf provides many possibilities for the introduction of deterrent features to the substrate James River, 1993~.
|
From page 47... ...
It also makes it relatively easy to introduce transparencies. The plastic may itself incorporate various additives and deterrent features.
|
From page 48... ...
However, it is highly effective against the casual photocopy, which does not copy the thread. Two enhancements to polyester security threads have been incorporated in foreign currencies.
|
From page 49... ...
Among them are planchettes, enhanced fibers, optical fibers, taggants, and particles with special properties. The enhancements for fibers and planchettes include: optically variable iridescence, dichroism, metamerism, microprinting, fluorescence, and phosphorescence.
|
From page 50... ...
They eclucat~on ot the general public would be required to render may, however, prove quite useful for point-of-sale devices, machine readability, and forgery detection sensors that could be built into copiers (see Counterfeit Deterrence Incorporated in Copiers and Printers later in this chapter)
|
From page 51... ...
As an alternative approach, the dipoles could possibly be printed on the paper with metallic ink; this approach would require further study to assess the printing resolutions and methods required, lon~term durability, etc. However, the committee is not aware of any currency development effort on this feature.
|
From page 52... ...
, who would be forced to make many plates and skillfully maintain precise registration while using several different inks. But printing fully multicolored notes on the existing intaglio printing presses is not a short-term possibility, since the BEP has a restricted number of additional ink fountains available on the current intaglio press equipment with which to apply other colors.
|
From page 53... ...
There are specialized line designs that show abnormal patterns when reproduced on color copiers; this effect is enhanced when subtle color patterns are used (Haslop, 1993a)
|
From page 54... ...
The various specialty inks that have potential for deterrence include: · color-shifting (optically variable) inks; · metameric ink pairs; · photochromic inks; · photoluminescent inks; · transparent or absorbing infrared inks; and · reflective inks.
|
From page 55... ...
An unaided eye will observe this effect as a color change as the viewing angle is changed. A color copier or scanner can copy a document only at one fixed angle relative to a document's surface.
|
From page 56... ...
~ Color-shifting ~ Pigment - Substrate MgF2 ~AI~//////////// MgF2 FIGURE 4-6 Cross-section of color-shifting pigment. The intaglio inks with color-shifting thin-film flakes that are currently available produce a readily observed color change versus viewing angle under conditions of normal illuminat~on.5 The colors that are observed at normal incidence and 45° relative to the surface normal depend on the thin film thickness.
|
From page 57... ...
A brief description of the fabrication process will illustrate the difficulty in reproducing color-shifting inks. Ultrathin films are initially deposited on a flexible planar substrate in high vacuum using electron-beam or sputtering-deposition techniques.
|
From page 58... ...
However, the previous evaluations of metameric inks have judged their color changes to be too subtle to be an effective deterrent. Since the last committee report, there is no new evidence to suggest that this situation has changed.
|
From page 59... ...
Infrared inks are a potential source of covert anticounterfeiting features. Because they can not be duplicated by a color copier, they may provide an additional deterrent to augment
|
From page 60... ...
This wavelength range is compatible with a variety of inexpensive infrared light emitters and detectors, so detection technology is readily available to exploit the signature of infrared dyes on currency.6 For example, semiconductor lasers based on GaAlAs emit infrared laser light at wavelengths of 780-840 nm. These diodes are the same ones used in laser printers.
|
From page 61... ...
These phthalocyanine infrared inks are known for their heat resistance. Moreover, in tests of photochemical stability, the phthalocyanine dyes were very robust.7 These infrared dyes can potentially provide useful and reliable anticounterfeiting measures as both overt and covert deterrent features.
|
From page 62... ...
FIGURE 4-9 Digital image produced by a sampled Fresnel zone plate. these systems would produce the low-frequency moire fringe pattern but not the highfrequency grating pattern.
|
From page 63... ...
Induced moire (i.e., moire patterns due to aliasing in a sampled image system) has been used as a counterfeit-deterrent feature in various forms since the late 1970s for document security (Wicker, 1991; Canadian Banknote Company, 1966; Kendrick andJefferson, Ltd.
|
From page 64... ...
This indicates that the sampling registry was probably not the same for all the colors in the copier. In fact the latest approach in color copiers is to use color filter arrays in front of the imaging array; this automatically results in a different sampling registry for each color.
|
From page 65... ...
. This is below the practical resolution limit of intaglio printing.
|
From page 66... ...
Latent Images In the context of counterfeit-deterrent methods, the term "latent image" is used to refer to the method in which the variation surface-relief pattern of the ink obtained with the intaglio printing process is used to produce a different image when the image viewing angle is changed.~° Normally, the latent image is observed at large angles with respect to the surface normal, that is, at near grazing incidence. Several countries currently utilize latent images in their currency.
|
From page 67... ...
Post-Printed Optically Variable Devices Post-printed optically variable devices are those that are added after all other printing operations have been completed. They include diffraction-based devices-holograms, kinegrams, and pixelgrams; multiple diffraction gratings; thin-film devices; and hot-stamped metallic
|
From page 68... ...
Holograms are widely used as counterfeit-deterrent features for security documents and credit cards. The striking image that can be produced by a hologram provides a good overt security feature.
|
From page 69... ...
(See Rana7om Pattern/Encription Counterfeit Deterrence Concept.J The use of holograms for document security has been investigated extensively (American Bank Note Company, 1984; Battelle Columbus Laboratories, 1983, 1985, 1990; Bander, 1984; Church and Littman, 1991; Collins, 1986; Pagan, 1990, 1991; Martin, 1983~. A major shortcoming is the hologram's lack of durability under even normal usage when placed on a flexible substrate.
|
From page 70... ...
A pixelgram master typically contains over 10 gigabytes of binary data, and it takes between 10 to 20 hours to write a 20-mm by 26-mm pixelgram. Available optical effects include a positive/negative flip; switch on/off effects; specific color flips; and movement effects.
|
From page 71... ...
Multiple-Difffaction Gratings A diffraction grating is an optically variable device that consists of a series of finely spaced parallel grooves. Diffraction gratings can be formed on a wide variety of substrate materials, including metals, glass, polyesters, and polymers (or plastics)
|
From page 72... ...
ink. Color-shifting inks, discussed earlier in this chapter, exhibit the same type of color shift with angle observed the large-area TFIFs but at a lower apparent intensity, since the optically variable pigment is suspended in ink.
|
From page 73... ...
Embedded Zero-Order Diffraction Gratings Embedded zero-order diffraction gratings represent a new type of microstmcture device that may prove to be useful as a counterfeit-deterrent feature. The optical characteristics are similar to those of a thin-film interference filter in that striking color shifts are produced as the structure is rotated or tilted.
|
From page 74... ...
Random Pattern/Encryption Counterfeit-Deterrence Concept Implementation Using Two Visible Features This system has the potential to provide a very high degree of authentication of banknotes that even the determined professional counterfeiter cannot defeat. It does require the use of an automated reader.
|
From page 75... ...
A higher level of authentication could be implemented at the Federal Reserve banks, and possibly other locations, using automated high-speed readers. For example, if the fiber-optic pattern described above were implemented, the existence of the fibers themselves could easily be detected visually at points of sale.
|
From page 76... ...
Currency Recognition System One manufacturer of advanced color copiers has developed and installed in its latest copiers, a first-generation system to automatically identify an attempt to copy certain banknotes (lsujita, 1993~. If the equipment detects a forgery attempt, it prints a black or blank copy and can be programmed to then shut down until it is reset by a repairman.
|
From page 77... ...
This committee did not receive any information as to the efficiency of the process against simple countermeasures. Since the print engines in color copiers will also function as computer-driven output devices, it is not clear what degree of protection will be provided by the forgery detection feature in computer printers.
|
From page 78... ...
Obvious and intuitive special features such as holograms may have defeated color copiers and other forms of electronic printing but could be relatively easy for proficient counterfeiters to simulate otherwise. They may even be counterproductive in the sense that they may reduce the practical life of the note or focus attention on a single feature of the note.
|
From page 79... ...
Thus it would seem there are obvious avenues for greater sharing of experience and for a collective approach to research in detection and deterrence in the future. RECOMMENDATIONS Although there are many new features that can be used to deter counterfeiters, the BEP should continue to utilize intaglio printing, the security thread, and the current substrate material as methods of deterrence against "classical" printing technologies and present day reprographics.
|
From page 80... ...
Longer-term plans for advanced deterrents Listed in alphabetical order) should include adclitional development and understanding of the following features: · diffraction-based holograms and related devices; · embedded zero-order diffraction gratings; laminated paper substrates with selected features; · metallic or specular woven security features;
|
From page 81... ...
These may involve synergistic combinations of visible and hidden covert features that could be related in some way, such as through a public key encryption system. The Department of Treasury should encourage U.S.
|
From page 82... ...
1987a. Thin Film Optically Variable Article and Method Having Gold to Green Color Shift with Angle and Method.
|
From page 83... ...
1991. Machine Reading of Visual Counterfeit Deterrent Features and Summary of U.S.
|
From page 84... ...
Haslop, Thomas De La Rue Company, on international experience with counterfeit deterrence features to the Committee on Next-Generation Currency Design. March 1993.
|
From page 85... ...
1990. Optically variable films, pigments, and inks.
|
From page 86... ...
1990. Optically variable films, pigments, and inks.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.