Abstract:
A labeling method for marking a product with invisible information. The label includes a removable laminate formed from a light transmissive layer, and a light transmissive adhesive that detachably affixes the label to a product. The label includes an invisible marker that contains information, detectable by light of selected wavelength. The amount of marker selected is sufficient to allow information in the marker to be detected only when the laminate is affixed over a surface with a selected optical background. The label laminate is removed from the surface of the product and affixed to a surface having the selected optical background and is exposed to light that renders the information in the marker detectable. The method allows covert information in the label laminate to be reliably detected and read with the use of minimal quantities of marker material.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention generally relates to a security label and method of labeling, and is specifically concerned with a detachably removable label laminate that requires the incorporation of only a very small percentage of marker material to reliably store and relay invisible information useful in authenticating and identifying a product. 
       BACKGROUND OF THE INVENTION 
       [0002]    If goods are not genuine, then product counterfeiting has occurred. If goods have been diverted from their intended channel of commerce by, for example, entering into a country where the goods are prohibited by contract or by law, then the goods have been subject to product diversion. 
         [0003]    Product counterfeiting occurs on artworks, CDs, DVDs, computer software recorded on CDs or diskettes, perfumes, designer clothes, handbags, briefcases, automobile and airplane parts, securities (e.g., stock certificates), identification cards (driver&#39;s licenses, passports, visas, green cards), credit cards, smart cards, and pharmaceuticals. According to the World Health Organization, more than 7% of the world&#39;s pharmaceuticals are bogus. This percentage is higher in some countries, such as Colombia, where up to 40% of all medications are believed to be fake. Until recently, the percentage of bogus medications in the United States has been virtually negligible due to a tightly controlled regulatory system has made it extraordinarily difficult for counterfeiters to sell or distribute suspect medications. However, the recent explosion of Internet drug sales from other countries and increasingly sophisticated counterfeiting techniques have substantially increased the amount of fraudulent drugs entering the United States. 
         [0004]    Product diversion has also occurred on many of the aforementioned goods. Such diversion could result in the sale and distribution of goods which do not comply with the product specifications required in the markets they are sold. For example, motorcycles intended to be sold without catalytic converters in a region with lower air pollution standards might be diverted to a region which does require such catalytic converters. Other negative effects include price inequities in certain markets, loss of exclusivity by some manufacturers or distributors, and damage to the goodwill, patent rights, and trademark rights of the manufacturer. Such diverted goods are sometimes referred to as “gray market” goods. Since the goods are genuine, it is sometimes difficult to determine whether the goods have been improperly diverted. This is especially true for a variety of goods such as, for example clothing, pharmaceuticals, and cosmetics. 
         [0005]    Labels for authenticating the origin and intended market of a good are known in the prior art. Since the persons who counterfeit or divert goods are also inclined to counterfeit such authenticating labels, label structures incorporating covert, authenticating data have been developed. An example of such a label includes both visible data, such as a printed trademark, a manufacturing serial number, or human readable product information, and invisible information which can authenticate the label as one which originated with or under the authority of the manufacturer. Such labels use an invisible marker material which is incorporated in the label. The data stored in the marker becomes readable when the label is exposed to light of a particular wavelength. 
       SUMMARY OF THE INVENTION 
       [0006]    While prior art labels incorporating invisible markers can provide authentication and identification data for a good, the applicants have observed a number of shortcomings associated with their use and manufacture. For example, the data in invisible, optically detected markers cannot be reliably detected or read when printed or placed over black text because of the black text&#39;s light absorption at ultraviolet, visible and infrared wavelengths. Reliable detection and reading of such data over specularly reflective backgrounds, such as silver foil, is similarly difficult because of light scattering. Detection over colored backgrounds is problematical because of the absorption of various wavelengths. Sometimes, the noise in the data signal caused by black text or specular reflection or colors can be compensated for by increasing marker levels to increase the strength of the signal. However, such a solution is expensive, as marker materials (which are often formed from rare earth metals) typically cost about between $1 and $10/gram. Since such prior art labels already require the invisible marker material to constitute as much as 5% of the weight of the label component that they are imbedded in, further increases in the use of such an expensive material is undesirable. Moreover, any substantial increase in the proportion of such marker material compromises the invisibility of the marker and/or detectability of the marker by non-optical means and can also adversely change the physical characteristics of the material that it is imbedded in. High marker concentrations can lead to a change in properties (viscosity, opacity, adhesion etc) of the materials that function as carriers. In addition, the final label/laminate system with high security marker concentrations may appear cloudy or stained depending on the marker and technique employed. Detection and ultimately unauthorized replication (counterfeit) risks increase with high marker loads. 
         [0007]    The invention is an improved label and labeling method that substantially reduces the amount of marker material necessary to reliably store and relay invisible product data. To this end, the label of the invention comprises a laminate that includes a light transmissive layer of sheet material, a light transmissive layer of adhesive that detachably affixes the sheet material over the surface of a product, a product package or a label substrate, and an amount of invisible marker incorporated into the sheet material or adhesive that contains invisible information detectable by light having a selected wavelength. The amount of marker selected is sufficient to allow information in the marker to be detected only when the laminate is affixed over a surface that provides a selected optical background that maximizes the detectability of the marker. In the preferred embodiment, the selected background is a white background. The ability of the label laminate to be removed from the surface of a product, a product package or a label substrate and positioned over such a background eliminates the optical interference associated with most backgrounds and greatly reduces the amount of marker material required for reliable detection a reading. For example, in contrast to the 5 weight percent quantities of marker material used in the prior art, the label laminate of the invention requires a quantity of marker material of only between about 0.01 and 0.001 percent by weight or less. 
         [0008]    The invisible information incorporated in the marker may be as simple as the presence of the marker, or it may take the form of a specific pattern formed by the marker. Examples of such patterns include one and two-dimensional bar codes capable of storing information in digitized form, as well as herringbone, alphanumeric and other repetitive patterns and patterns formed from varying densities of marker material capable of storing information in analogue form. 
         [0009]    Marker in particulate form may be mixed directly with the material used to form the sheet material layer and/or the adhesive layer, or positioned between these two layers. A pattern of marker may also be printed on a surface of the sheet material layer or the adhesive layer by an ink or varnish containing fine particles of the marker. Any number of printing techniques may be used to print the marker on one of the surfaces of the label laminate, including thermal transfer, electro-photographic, flexography, gravure, offset, and inkjet. 
         [0010]    The label may further include a label substrate that the layer of adhesive of the laminate detachably affixes the sheet material layer to, wherein the optical background provided by the surface of the label substrate interferes with the readability of the data contained within the marker. The background provided by the label substrate may be selected to conceal any visible traces of the existence of a marker on the laminate or to make detection of the marker difficult if not impossible, even when the label laminate is exposed to light of the selected wavelength that renders the information incorporated into the mark readable. The label substrate may also contain visible graphics or product information. 
         [0011]    The marker may be a fluorescent or phosphorescent material, and the selected wavelength that the marker is exposed to may be the excitation wavelength of the fluorescent or phosphorescent material. The selected excitation wavelength may be within the ultraviolet, visible or infrared range. While the light emitted by the fluorescent or phosphorescent marker material will be a different wavelength than the excitation wavelength, the emitted light may also be within the ultraviolet, visible or infrared range. When the emitted light is in the visible range of wavelengths, the detection of the information incorporated in the marker may be readable by the unaided human eye or it may be machine-readable. The marker may also be a material that absorbs an ultraviolet or infrared wavelength, and the selected wavelength may be the wavelength that is absorbed by the marker. In such an embodiment, detection of the information would be by a reading device capable of “seeing” the dark patterns generated when the marker was exposed to the absorbed ultraviolet or infrared wavelength. Two or more markers with different excitation or absorption wavelength properties may be incorporated, imbedded, or printed onto one of the label laminate components to render counterfeiting of the label laminate more difficult. 
         [0012]    Finally, the invention also encompasses a method for labeling products and product packages with invisible information. This method generally comprises the steps of (1) providing a layer of light transmissive sheet material with a light transmissive layer of adhesive that detachably affixes the sheet material layer to a surface; (2) providing an amount of invisible marker to either the sheet material or the adhesive that contains invisible information that is detectable by light having a selected wavelength, wherein the amount of marker selected is sufficient to allow information in the marker to be detected only when the laminate is affixed over a surface that provides a selected optical background; (3) detachably affixing the layer over a surface of one of a label substrate or product or product package; (4) removing the label laminate from the surface of one of a label substrate or product or product package and placing it over a surface having the selected optical background; and (5) exposing said marker with light having the selected wavelength and detecting the emitted light containing the information. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is side cross sectional view of one embodiment of the label laminate of the invention adhered to a product or product package that includes a label substrate with carbon black printing thereon, wherein the invisible marker is printed in a pattern on the upper surface of the light transmissive sheet material of the laminate; 
           [0014]      FIG. 2  is a second embodiment of the invention which is structurally identical to the embodiment of  FIG. 1  with the exception that the invisible marker is dispersed in the material forming the light transmissive sheet material of the laminate; 
           [0015]      FIG. 3  is a third embodiment of the invention which is structurally identical to the embodiment of  FIG. 1  with the exception that the invisible marker is dispersed in the material forming the adhesive layer of the laminate immediately beneath the light transmissive sheet material of the laminate; 
           [0016]      FIG. 4  is a fourth embodiment of the invention which is structurally identical to the embodiment of  FIG. 3  with the exceptions that the invisible marker is backside printed in the material forming the adhesive layer of the laminate immediately beneath the light transmissive sheet material of the laminate, and the label substrate has no carbon black printing thereon; 
           [0017]      FIG. 5  illustrates a label laminate consisting of the light transmissive sheet material and layer of adhesive that have been peeled off of the label substrate illustrated in  FIG. 1  and affixed to a non-interfering optical background; 
           [0018]      FIG. 6  illustrates the exposure of the label laminate illustrated in  FIG. 5  to light having a wavelength that excites or is absorbed by the marker printed on the top surface of the sheet material; 
           [0019]      FIGS. 7A-7D  illustrate the method of the invention with the label laminate in plan view, including the steps of peeling off the label laminate from a label substrate having optically interfering carbon black printing, affixing the peeled off laminate to an optically non-interfering background, and exposing the laminate to a wavelength of light that excites or is absorbed by the marker printed on one of the layers of the laminate to expose a two-dimensional bar code; 
           [0020]      FIG. 8  illustrates the relative angular orientation a of an illumination source of incident light and the optical detection component of the marker-reading device described with respect to Example 1; and 
           [0021]      FIGS. 9A and 9B  are a cross-sectional view and top view, respectively of an optical component holder for the marker-reading device described with respect to Example 1. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0022]    With reference to  FIG. 1 , wherein like numerals designate like components throughout all of the several figures, a first embodiment of the label  1  of the invention comprises a label laminate  2  formed from a layer of light transmissive sheet material  3  and a layer of adhesive  5 . 
         [0023]    The light transmissive sheet material  3  is preferably transparent, and may be a flexible film formed from an, extrudible polypropylene resin such as bi-axially oriented polypropylene (BOPP). Such film has good clarity, resistance to UV light, excellent chemical and abrasion resistance, and a smooth surface. Polyester and polyolefin films may also be used. Film thickness preferably ranges from 0.5 to 2 mil, although smaller and greater thicknesses are also within the scope of the invention. Specific examples of films which may be used to form layer  3  include THERMLfilm, Select 10852, 1 mil, available from Flexcon located at www.flexcon.com, and 2 mil clear BOPP sold by Fasson Roll North America located at www.fasson.com, and Fasclear 350, 3.4 mil polyolefin film also available from Fasson Roll North America. 
         [0024]    The light transmissive layer of adhesive  5  can be any one of a number of transparent pressure sensitive adhesives (PSAs), including alkyl (meth)acrylate based adhesives and latex based adhesives, and is preferably transparent. A specific example of such an adhesive is 3M Fastbond™ Pressure Sensitive Adhesive 4224NF (Clear) available from 3M Company located in Minneapolis, Minn. Film thickness of the adhesive layer  5  preferably ranges from 0.5 to 2 mil, although smaller and greater thicknesses are also within the scope of the invention. While both the layer of transmissive sheet material  3  and the layer of adhesive  5  are preferably transparent, they may also be translucent. 
         [0025]    The label laminate  2  also includes an invisible marker  7  that contains information. In the case of the first embodiment label  1  illustrated in  FIG. 1 , the marker  7  is formed from a particulate marker material that is mixed with a carrier (such as a clear, flexible varnish) to form a transparent ink. The transparent ink is then printed in a pattern  9  on the upper surface of the layer of transparent sheet material  3 . The pattern can be alpha numeric, geometric (such as a herringbone pattern), a logo, a geometric shape, or a linear or two-dimensional barcode. Printing may be accomplished by thermal transfer, flexography, gravure, offset, and inkjet. Materials used as markers may be of a light emissive type, a light reflective type, or a light absorptive type. In all cases, the marker material is illuminated with light from an incident light source which may have a UV wavelength (250-400 nm), a visible wavelength (400-700 nm) or IR wavelength (700-2000 nm). The marker  7  will emit, reflect, or absorb light, ideally in a contrasting manner with respect to the background. Thus the resulting marker image signals can appear either higher or lower in intensity as compared to the background. Given an appropriate imaging device, or reader, one can detect both the presence of the marker  7 , and any information-containing pattern  9  the marker  7  is arranged in, and thus verify its authenticity by virtue of contrasting marker image signals as compared to the background. 
         [0026]    The label  1  further includes a label substrate  11 . The label substrate  11  is preferably the same size and shape of the label laminate  2  such that the outer edges of the label laminate  2  are concealed when it is removably affixed to the upper surface of the label substrate  11  via the layer of adhesive  5 . The substrate may be formed from any one of a number of paper or plastic sheet materials and preferably provides a background which conceals the presence of the marker  7 . Such concealing backgrounds include specular (i.e. metallic or glassy) backgrounds, variable ink backgrounds and hologramic backgrounds for the printed information  13 . The label substrate  11  may have printed information  13  on its upper surface that provides optical interference that further impairs both the detection and the reading of the information in the marker  7 . Such printed information  13  may be printed in a visible, dark saturated color ink or carbon-black based ink or a combination of both. The combination of the light absorptive properties of the printed information  13  and the light scattering properties of the upper surface of the label substrate  11  renders the marker  7  difficult, if not impossible to detect either visually or with a specialized light source. 
         [0027]    Finally, the label  1  includes a second layer of adhesive  15  for affixing the label  1  to the surface  17  of either a product or a product package. The layer of adhesive  15  may be either permanent or temporary and need not be transparent or light transmissive. Any one of a number of commercially available adhesives may be used to form the second layer of adhesive  15 . 
         [0028]      FIG. 2  illustrates a second embodiment of the label  20  of the invention which is structurally the same as the first described embodiment of label  1 , with the exception that the marker  22  is uniformly distributed throughout the material forming the transparent transmissive sheet material  3 . In this embodiment, authenticity of the label is determined by the detected density of the marker  22 . In a variation of this embodiment, a second marker  23  having different optical properties may be mixed in a preselected proportion with the marker  22 , and authenticity may be determined not only by detecting the presence of both markers  22  and  23 , but by determining whether their relative proportions correspond to the preselected proportions. 
         [0029]      FIG. 3  illustrates a third embodiment of the label  25  of the invention which is structurally the same as the first described embodiment label  1 , with the exception that the marker  27  is uniformly distributed throughout the material forming the layer of adhesive material  5 . While not specifically shown in  FIG. 3 , one or more second markers, each having different optical properties, may be mixed in with the first marker  27  in selected proportions such that authentication is achieved by optically determining if the relative proportions of the several markers correspond to the preselected proportions. 
         [0030]      FIG. 4  illustrates still another embodiment of the label  30  of the invention which is structurally the same as the first described embodiment label  1 , with the exception that the marker  32  is formed from a marker material that is mixed with a carrier (such as a clear, flexible varnish) to form a transparent ink which is then printed in a pattern  9  on the lower surface of the layer of transparent adhesive  5 . 
         [0031]      FIGS. 5 and 6  illustrate the operation of the label laminate  2 . Here, the label laminate  2  from the embodiment of the label illustrated in  FIG. 1  has been peeled off of the label substrate  11  and affixed, via the adhesive layer  5 , to a background surface  34  that optimizes the detectability and the readability of the marker  7 . Incident light  36  of a selected wavelength is applied over the surface of the marker  7 , resulting in reflected or emitted light  38 . Emitted light  38  may be the same or a different wavelength than the incident light  36 . When the marker  7  is formed from an emissive material which undergoes photonic excitation when exposed to light having a selected wavelength incident light  36 , the emitted light is of a different wavelength emitted light  38 . This emitted light  38  can be in virtually any wavelength including, UV, visible or IR. Again, with an appropriate imaging device, one can detect the presence of security marker via recognition of localized areas of emitted light  38 , and can further read the information incorporated therein. 
         [0032]    The following table summarizes the nature of incident and emitted wavelengths of light for emissive markers  7 : 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Wavelength (λ) Summary 
               
             
          
           
               
                 Type 
                 Incident/Excitation 
                 Emitted 
               
               
                   
               
               
                 Represented by 
                 A 
                 B 
               
               
                 λ Wavelength Range 
                 UV-&gt;Visible-&gt;IR 
                 UV-&gt;Visible-&gt;IR 
               
               
                 Comparison 
                 A can be &gt; or &lt; B 
                 B can be &gt; or &lt; A 
               
               
                   
               
             
          
         
       
     
         [0033]    In the case where λB&lt;λA, an up-converting property of a security marker is utilized. Materials that exhibit this property include certain phosphors and organic dyes. Typically high power incidence radiation, such as obtained with laser sources is required to obtain an up-converted emission. Wavelength shifts include IR to shorter IR, IR to visible, visible to shorter visible. Examples of such materials include, anti-Stokes pigments “A274” (IR to green), “A225” (IR to red) available from Epolin, Inc., Newark, N.J. USA (www.epolin.com). In the case where λB&gt;λA, the emissive material is functioning in a down converting mode. Lower power light sources, such as light emitting diodes, incandescent and fluorescent bulbs can be used to excite down converted emission responses. Many dyes and phosphors exhibit this property. Wavelength shifts include UV to visible, visible to longer visible, visible to IR, IR to longer IR wavelengths. A few examples of such materials include “L-142, L-212, L-88”, (UV to visible) available from Beaver Luminescers, Newton, Mass. USA (www.luminescers.com). A variation on excitation emission utilizes the variation in temporal profile of the intensity of emitted light over time. The unique time signature of the marker  7  is thus confirmed. U.S. Pat. No. 6,996,252 provides an example of the use of decay time differences to verify authenticity of a document. All emissive materials can be verified by relative intensity decay measurement, with a reader designed to detect responses in the appropriate time regime. 
         [0034]    In the case where the marker  7  is light absorptive, both the incident  36  and the emitted light  38  will be of the same wavelength, the image signals resulting from differences in absorption of incident light  36 , and thus differences in diffuse reflectance of that incident light  36 . A properly designed and calibrated imaging device, or reader, will provide image information and will confirm or deny the presence of security maker. An example of a light absorptive marker  7  is FHI9072 from Fabricolor Holding, www.fabricolorholding.com. 
         [0035]      FIGS. 7A-7D  illustrate the method of the invention with the label  1  in plan view. As illustrated in  FIG. 7A , a label  1  such as that described with respect to  FIG. 1  is first adhered to the surface  17  of a product or product package. Such a label includes human readable printed information  13  in a carbon-based ink that is printed on a label substrate  11 . Label  1  further includes a transparent label laminate  2  that is adhered over the label substrate  11  via adhesive layer  5  and which is further dimensioned the same as the label substrate  11  so as to appear to be an integral part of the label  1 . The transparent label laminate  2  includes an invisible, digitized pattern  9  of marker  7  which is a two-dimensional bar code in this example. The “dark” squares of the two dimensional bar code are formed by digitized pattern of marker  7  distributed at a density of only between about 0.01 and 0.001 weight percent. The distribution density is dictated by the reading device sensitivity. In this example, label substrate  11  is aluminized so as to provide a shiny, specularly reflective background. The combination of the light absorptive carbon-black printed information  13  and the specular background provided by the surface of the label substrate  11  renders both the presence of the marker  7  in the laminate as well as the information embodied therein undetectable with all but the most sensitive detection devices. 
         [0036]    In the second and third steps of the method illustrated in  FIGS. 7B and 7C , the label laminate  2  is peeled off of the label substrate  11  and adhered, via the adhesive layer  5 , to a background surface  34  that provides an optimal optical background for the detection and reading of the marker  7  in the pattern  9 . In most cases, surface  17  will provide a white, diffusively reflecting background. 
         [0037]    In the fourth step of the method illustrated in  FIG. 7D , the label laminate  2  is exposed to incident light  36  of a selected wavelength from a light source  40 . 
         [0038]    Incident light source  40  may be simple illumination devices such as UV lights of varying form, (black lights, UV tubes, UV diode array “flashlights”), IR diode arrays, IR pens, visible LEDs, and laser diodes. When the emitted light  38  is both visible and human readable, the light source  40  may also constitute the reader  42 , as the information embodied within the marker may be gleaned from simple visual observation. When the emitted light  38  is either invisible to the human eye, or if the emitted light is visible, but the pattern  9  is machine readable only, then the combination of an incident light source  40  and a reading device  42  constitutes the reader, as both a light source  40  and a reading device  42  are necessary to read the information embodied within the marker  7 . 
       EXAMPLE 1  
       [0039]    Thermal transfer ribbon is prepared with a UV excitable material, UVXPBR. This particular material has the property of emitting red visible light after excitation with UV light, as described at www.maxmax.com. The UVXPBR is mixed with a clear resin (15% resin, 85% solvent, primary component 2-butanone) at a concentration of 1000 parts per million (ppm). This is accomplished by dissolving 0.03 g UVXPBR in 30 g resin solvent mixture and stirring to solution at room temperature. The resulting clear solution is hand coated on pre-slit 4″ wide thermal transfer ribbon with a number 4 Mier rod. Coated thickness after solvent evaporation is about 1 micron and the marker content in the resin is about 6667 ppm. Several hand coatings are completed in series and the ribbon is wound, coated side out, on a new 1″ core. 
         [0040]    The freshly prepared ribbon was threaded onto a Zebra model ZM400 thermal transfer printer. Along with this ribbon, 1″ round clear label laminates  2  produced by laminating a clear polyester base-liner label with Flexcon Thermlfilm select 10852 1 mil gloss polyester film are threaded into the printer. A data-containing pattern  9  consisting of 10×10 DataMatrix 2-dimensional bar code, with an edge length of 1.25 cm, was printed on the label laminate  2  via thermal transfer. 
         [0041]    The average marker surface density in a single square of the barcode, containing in the bar code area was 666.7 nanograms/cm2. The average marker density across the barcode area was about 360 nanograms/cm2 (since only about 46% of the bar code area was covered with marker). The average marker density across the 1″ round clear laminate  2  was 110 ng/cm2. 
         [0042]    The procedure described above was repeated, but with a marker level one-tenth that just described. This procedure produced label laminates  2  where the average marker surface density in a single square of the barcode, containing in the bar code area was 66.7 nanograms/cm2. The average marker density across the barcode area was about 36 nanograms/cm2 (since only about 46% of the bar code area was covered with marker). The average marker density across the 1″ round clear label laminate  2  was 11 ng/cm2. 
         [0043]    The resulting transparent label laminates  2  containing marker  7  at the two different levels were applied to four different optical background surfaces  34  to compare the detectability of the marker  7  and the readability of the data-containing pattern  9 . The first optical background was a white 3×5 card that had been treated with optical brightener. The second optical background was card stock that did not contain optical brightener. The third optical background was metallic poly sheeting, and the fourth optical background was black construction paper. 
         [0044]    The marker printed pattern  9  for the label laminates  2  containing marker  7  at the two different levels was detected and read over the four different backgrounds by three different methods. 
         [0045]    In the first method, incident light  36  was directed toward the surface of the label laminate  2  at an angle a of 45° and the resulting emitted light  38  was read at an angle of 90° as illustrated in  FIG. 8 . This was implemented by LEDs  45   a,    45   b  in combination with an optical component holder  47  as illustrated in  FIGS. 9A and 9B . Component holder  47  overlies and is centered over the pattern  9  printed on the label laminate  2 . The label laminate  2  in turn overlies an optical background surface  34  which is one of the four aforementioned sheet materials. This component holder  47  is constructed of plastic and is approximately 2 inches in diameter. LEDs  45   a,    45   b  are placed in alignment with two of the four angled holes  48 . The LEDs  45   a,    45   b  are oriented 90° degrees with respect to one another, 45° from the plane of the sample label laminate  2 , and 45° from the placement of the photodiode, as depicted in  FIG. 9A . The remaining two angled holes  48  for LEDs were left empty. The LEDs  45   a,    45   b  were Roithner (located in Vienna, Austria) part number UVLED375-10-30 LEDs operated with 20 mAmp drive current. A reader  42  in the form of an Ocean Optics USB2000 model fiber optic spectrometer with a photodiode, charge coupled device (CCD) was optically coupled with hole  50  in the component holder  47  via a fiber optic cable (not shown). 
         [0046]    In the first detection method, data was collected as a function of wavelength. The UVXPBR marker has a single emission at 614.26 nm and the intensity of the emission detected by the Ocean Optics spectrometer at this wavelength is reported in Table 1A as the marker signal. In Table 1A, it is clear that this emission was diminished when the clear label was read over a black or metallic background and enhanced over a white background. An enhanced signal was obtained when a white reading background was used and an optimum signal was obtained if the white background was itself non-emissive, in other words, if it did not contain optical brightener. (Optical brightener is added to most white paper to enhance appearance.) The signal enhancement was most noticeable at the higher marker level. The lower marker level, especially on black, gave signals close to the detection limit of the spectrometer. A blank measurement was made on a white Spectralon sample. This sample is highly, diffusely reflective. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
               
             
               
               
               
               
               
             
           
               
                 TABLE 1A 
               
             
             
               
                   
               
               
                 Detectability of Marker UVXBR Data at 614.26 nm for Label with 
               
               
                 Laminate in Example 1 with a Photodiode CCD Detector 
               
             
          
           
               
                   
                   
                   
                   
                 Relative 
               
               
                   
                 Marker Level 
                   
                 Signal 
                 signal 
               
               
                 Example 
                 in bar code 
                 Optical 
                 strength at 
                 strength at 
               
               
                 type 
                 area (ng/cm2) 
                 Background 
                 614.26 nm 
                 614.26 nm 
               
               
                   
               
             
          
           
               
                 High marker level 
               
             
          
           
               
                 comparison 
                   
                 Blank* 
                  0 
                 0 
               
               
                 comparison 
                 360 
                 1d - black 
                  83 
                 1 
               
               
                 comparison 
                 360 
                 1c - metallic 
                 234 
                 2.8 
               
               
                 invention 
                 360 
                 1a - white with 
                 567 
                 6.8 
               
               
                   
                   
                 optical 
               
               
                   
                   
                 brightener 
               
               
                 invention 
                 360 
                 1b - white no 
                 963 
                 11.6 
               
               
                   
                   
                 optical 
               
               
                   
                   
                 brightener 
               
             
          
           
               
                 Low marker level 
               
             
          
           
               
                 comparison 
                   
                 blank 
                  0 
                 0 
               
               
                 comparison 
                 36 
                 black 
                  20 
                 1 
               
               
                 invention 
                 36 
                 1a - white with 
                  ~50* 
                 2.5 
               
               
                   
                   
                 optical 
               
               
                   
                   
                 brightener 
               
               
                 invention 
                 36 
                 1b - white no 
                  79 
                 4 
               
               
                   
                   
                 optical 
               
               
                   
                   
                 brightener 
               
               
                   
               
             
          
         
       
     
         [0047]    In the second method of detection, no optical component holder  47  was used. Instead, the arrangement illustrated in  FIG. 7D  was used with the light source  40  and reader  42  oriented at an approximately 45° angle from the plane of the label laminate  2 . In this method, the reader  42  was a digital Nikon 995 camera having a CCD array which was placed on a tripod approximately 2.4 inches from the label laminate  2  to detect the marker pattern  9 . A 550 nm long pass filter was placed in front of the Nikon 995 camera to reduce noise in the signal. The light source  40  used to illuminate the label laminate  2  was a flashlight comprised of five 365 nm LEDs and with an output power of approximately 8 to 10 mW. Illumination and detection was conducted in a darkened room. Images of the pattern  9  comprised of the reflected and emitted light from the pattern  9  were captured using ISO800, 1-second exposures. Similar images were captured with no illumination from the light source  40 . The illuminated and non-illuminated images were subtracted from one another using ImageJ software, (www.rsb.info.nih.gov/ij). Examination of the subtracted image was used to determine marker detectability. The subtracted-image 2D barcode was read and decoded with software from Omniplanar (Subsidiary of Honeywell, www.omniplanar.com) although software from Labview (National Instruments Corporation (www.ni.com/labview)) could also be used. It is possible to visually detect the presence of the pattern  9  but not have a clear enough image of the pattern  9  to decode the barcode. The detectability and readability of the pattern  9  is tabulated in Table 1B as a function of the optical background behind the clear label laminate  2 . The marker was most detectable and most decodable on white, diffusively reflective backgrounds. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                 TABLE 1B 
               
             
             
               
                   
               
               
                 Detectability of Marker UVXBR Red Emission Using a Digital 
               
               
                 Camera with a 550 nm Long Pass Filter. Decodability Was Determined 
               
               
                 Using Standard 2D Bar Code Detection Software. 
               
             
          
           
               
                   
                 Marker Level 
                   
                 Detectability and 
               
               
                 Example 
                 in bar code 
                 Optical 
                 Decodability of Marker 
               
               
                 type 
                 area (ng/cm2) 
                 Background 
                 data 
               
               
                   
               
             
          
           
               
                 High marker level 
               
             
          
           
               
                 comparison 
                 360 
                 1d - black 
                 Mark was detectable but 
               
               
                   
                   
                   
                 not decodable 
               
               
                 comparison 
                 360 
                 1c - metallic 
                 Mark was detectable but 
               
               
                   
                   
                   
                 not decodable 
               
               
                 invention 
                 360 
                 1a - white with 
                 Mark was detectable and 
               
               
                   
                   
                 optical 
                 decodable 
               
               
                   
                   
                 brightener 
               
               
                 invention 
                 360 
                 1b - white no 
                 Mark was detectable and 
               
               
                   
                   
                 optical 
                 decodable 
               
               
                   
                   
                 brightener 
               
             
          
           
               
                 Low marker level 
               
             
          
           
               
                 comparison 
                 36 
                 black 
                 Not detected 
               
               
                 invention 
                 36 
                 1a - white with 
                 Mark was detectable but 
               
               
                   
                   
                 optical 
                 not decodable 
               
               
                   
                   
                 brightener 
               
               
                 invention 
                 36 
                 1b - white no 
                 Mark was detectable but 
               
               
                   
                   
                 optical 
                 not decodable 
               
               
                   
                   
                 brightener 
               
               
                   
               
             
          
         
       
     
         [0048]    In the third method of detection, the same orientation between the light source  40  and reader  42  was used as described with respect to the second method. Again, a flashlight comprised of five 365 nm LEDs and with a output power of approximately 8 to 10 mW was used to illuminate the label laminate  2  in a darkened room. However, emitted and reflected light from the label laminate  2  was examined by eye for each of the four background surfaces  34  of black, reflective, white plus optical brightener and white sheet materials. Results are summarized in Table 1C. In this method of detection, the black background was optimum for a readable barcode. This is because the human eye has difficulty distinguishing a weak red signal superimposed on stronger blue-white emissions from optical brightener. The metallic background also gave a sharper image, as perceived by eye, than the white substrates. This example demonstrates that the optimal background for reading may depend on the method of detection. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
             
               
               
               
               
             
               
             
               
               
               
               
             
           
               
                 TABLE 1C 
               
             
             
               
                   
               
               
                 Human Detectability of Red Emission from Marker UVXBR 
               
             
          
           
               
                   
                 Marker Level 
                   
                 Quality of 
               
               
                 Example 
                 in bar code 
                 Optical 
                 emissive red 
               
               
                 type 
                 area (ng/cm2) 
                 Background 
                 marker image 
               
               
                   
               
             
          
           
               
                 High marker level 
               
             
          
           
               
                 invention 
                 360 
                 1d - black 
                 Dim but sharp, sharper 
               
               
                   
                   
                   
                 than 1c 
               
               
                 invention 
                 360 
                 1c - metallic 
                 Dim but sharp 
               
               
                 comparison 
                 360 
                 1a - white with 
                 Obscured by 
               
               
                   
                   
                 optical brightener 
                 white-blue optical 
               
               
                   
                   
                   
                 brightener emission 
               
               
                 comparison 
                 360 
                 1b - white no 
                 Visible but obscured 
               
               
                   
                   
                 optical brightener 
                 by white-blue emission 
               
               
                   
                   
                   
                 of substrate 
               
             
          
           
               
                 Low marker level 
               
             
          
           
               
                 invention 
                 36 
                 black 
                 Barely detectable as 
               
               
                   
                   
                   
                 red blur 
               
               
                 comparison 
                 36 
                 1a - white with 
                 Not detectable 
               
               
                   
                   
                 optical brightener 
               
               
                 comparison 
                 36 
                 1b - white no 
                 Not detectable 
               
               
                   
                   
                 optical brightener 
               
               
                   
               
             
          
         
       
     
       EXAMPLE 2  
       [0049]    A thermal transfer ribbon is prepared with A-225 up-converting IR excitable material available from Epolin, Inc. This particular material has the property of emitting green visible light after excitation with IR light, as described at www.epolin.com. The A-225 material is mixed with a clear resin (15% resin, 85% solvent, primary component 2-butanone) at a concentration of 1000 ppm. This is accomplished by mixing 0.03 g A-225 with 30 g resin solvent mixture and vigorously stirring to dispersion at room temperature. The resulting mixture is hand coated on pre-slit 4″ wide thermal transfer ribbon with a number 4 Mier rod. Coated thickness after solvent evaporation is about 1 micron and the marker content in the resin is about 6667 ppm. Several hand coatings are completed in series and the ribbon is wound, coated side out, on a new 1″ core. The freshly prepared ribbon is threaded onto a Zebra model ZM400 thermal transfer printer. Along with this ribbon, 1″ round clear labels, produced by laminating a clear polyester base linered label with Fasson 2 mil clear BOPP 7525/S4900, are threaded into the printer. Patterns  9  are printed on the label laminate  2  via thermal transfer. 
         [0050]    The resulting transparent label laminates  2  were applied to a series of optical background surfaces  34  including white 3×5 cards, metallic poly sheeting, and black construction paper. Each sample label laminate  2  was illuminated with a light source  40  in the form of a hand held infrared laser, and visually observed. Marked patterns  9  were visible and were green in color when viewed on the label applied to white 3×5 cards. By contrast, when freshly printed label laminates  2  were applied to metallic poly sheeting, green emission was not visually detectable. Similarly, no emission was visually detected when infrared laser light was applied to a label laminate  2  overlying black paper. 
         [0051]    This example illustrates that an invisible pattern  9  of marker  7  could be printed on a laminate that overlies a highly reflective or black surface, which could be either the surface of a label substrate  11  or the surface of a product or product package. Detection would be accomplished by removal of the marked label laminate  2 , affixing the laminate on white paper followed by illumination with IR light and visual detection with a human eye or a camera or other reading device  42 . 
       EXAMPLE 3  
       [0052]    In this example, an IR absorbing dye was dissolved in 2-butanone, then mixed into a removable acrylic adhesive mixture at a concentration of 5000 ppm. The dye used was FHI9072, described on www.fabricolorholding.com. The adhesive mixture was coated on 2-mil polyester film to a thickness of 1 mil., thus forming the adhesive layer  5  of a label laminate  2 . This resulted in a marker concentration of 12.5 microgram/cm2. The resulting label laminate  2  was then adhered over a polyester label substrate  11  and die-cut to shape. The resulting label  1  had no apparent visible colorations due to the IR dye. 
         [0053]    Detection of the dye was accomplished via IR reflectance. The light source  40  was a digital Nikon 995 camera modified to remove the IR filter that normally covers the CCD array. The reader  42  used was a digital Nikon 995 camera in which a 650 nm long pass filter was placed in front of the lens in order to reduce noise in the signal. The camera was placed in a tripod approximately 2.4 in from the sample. An array of 910 nm IR LEDs was used to irradiate the label laminate  2  in a darkened room. Images of the sample label laminate  2 , comprised of the reflected light from the sample, were captured using ISO800, 1-second exposures. When a marked laminate was applied over a black surface, all incident IR light is absorbed and no signal is detected. When the removable laminate/adhesive system was removed and applied to a white background, the IR reflectance scan indicated the presence of dye due to low reflectivity as compared to the black surface. 
         [0054]    These examples demonstrate the usefulness of detecting security markers by reading through a clear label placed over an optimal optical background. This invention can be applied to any type of emissive or reflective optical marker  7  and any type of detection system that measure reflected and/or emitted light. If more sensitive detection systems are used, the level of marker  7  used will be lower. If less sensitive detection systems are used, the concentration of marker  7  used will be higher. 
         [0055]    Some examples of detection systems are given in the following references: U.S. Pat. No. 7,030,371; EP Patent No. 1 043 681; U.S. Pat. No. 7,079,230; U.S. Pat. No. 6,184,534; and U.S. Pat. No. 5,959,296. Commercial devices which could be used as detection devices for this application include document examination and verification devices such as the VSC5000, VSC6000 and VSC4 sold by Foster and Freeman. Examples of emissive and absorptive dyes and pigments are also available on the websites of vendors Epolin (www.epolin.com), Fabric Color Holding Inc. (www.fabricolorholding.com/browse.php), Beaver Luminescers (www.luminescers.com/products.html), and LDP LLC dyes and pigments (www.maxmax.com/aSpecialtyInks.htm). 
         [0056]    Organic markers may be compounds of the following type: indanones, metal dithiolenes, oxazoles, thiazoles, thiodiazoles, thiazenes, triazoles, oxadiazoles, pyrazolines, oxinates, benzoxazinones, benzimidiazoles, benzthiazoles, phthalazines, thioxanthenes, triarylamines, triarylmethanes, tetraaryldiamines, stilbenes, cyanines, rhodamines, perylenes, aldazines, coumarines, spirooxazines, spiropyranes, cumene, anthranilic acids, terephthalic acids, bartituric acids, and derivatives thereof. Examples of inorganic emissive materials are given in U.S. Pat. No. 6,436,314 and in the reference T. Soukka et al., Journal of Fluorescence, Vol. 15, No. 4, July 2005. Examples of inorganic emissive materials containing rare earth elements are CaWO 4 :Eu; CaMoO 4 :Mn, Eu; BaFBr:Eu; Y 2 O 2 S:Tb; Y 2 O 2 S:Er, Yb; Y 2 O 2 S:Er; Y 2 O 2 S:Eu; Y 2 O 3 :Eu; Y 2 O 2 S:Eu+Fe 2 O 3 ; Gd 2 O 2 S:Tb; Gd 2 O 2 S:Eu; Gd 2 O 2 S:Nd; Gd 2 O 2 S:Yb, Nd; Gd 2 O 2 S:Yb, Tm; Gd 2 O 2 S:Yb, Tb; Gd 2 O 2 S:Yb, Eu; LaOF:Eu; La 2 O 2 S:Eu; La 2 O 2 S:Eu Tb; La 2 O 2 S:Tb; BaMgAl 16 O 27 :Eu; Y 2 SiO 5 :Tb, Ce; Y 3 Al 5 O 12 :Ce; Y 3 Al 2.5 Ga 2.5 O 12 :Ce; YVO 4 :Nd; YVO 4 :Eu; Sr 5 (PO 4 ) 3 Cl:Eu; CaS:Eu; ZnS:Ag, Tm and Ca 2 MgSi 2 O 7 :Ce. Examples of inorganic emissive materials that do not contain rare earth elements are: ZnS:Cu, ZnS:Cu, Au, Al; ZnS:Ag; ZnSiO 4 :Mn; CaSiO 3 :Mn, ZnS:Bi; (Ca, Sr)S:Bi; (Zn, Mg)F 2 :Mn; CaWO 4 ; CaMoO 4 ; ZnO:Zn; ZnO:Bi, and KMgF 2 :Mn. Examples of emissive dyes which can be used in the application are given in U.S. Pat. No. 6,514,617. Infrared absorbing and emitting dyes which can be used as markers for this invention are referenced in the following table of U.S. Pat. No. 7,068,356 (see below): 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 1D 
               
               
                   
                   
               
               
                   
                 Dye Name/No. 
                 Excitation 
                 Emission 
               
               
                   
                   
               
             
             
               
                   
                 Alcian Blue 
                 630 nm 
                 Absorbs 
               
               
                   
                 (Dye 73) 
               
               
                   
                 Methyl Green 
                 630 nm 
                 Absorbs 
               
               
                   
                 (Dye 79) 
               
               
                   
                 Methylene Blue 
                 661 nm 
                 686 nm 
               
               
                   
                 (Dye 78) 
               
               
                   
                 Indocyanine Green 
                 775 nm 
                 818 nm 
               
               
                   
                 (Dye 77) 
               
               
                   
                 Copper Phthalocyanine 
                 795 nm 
                 Absorbs 
               
               
                   
                 (Dye 75) 
               
               
                   
                 IR 140 
                 823 nm 
                 838 nm 
               
               
                   
                 (Dye 53) 
               
               
                   
                 IR 768 Perchlorate 
                 760 nm 
                 786 nm 
               
               
                   
                 (Dye 54) 
               
               
                   
                 IR 780 Iodide 
                 780 nm 
                 804 nm 
               
               
                   
                 (Dye 55) 
               
               
                   
                 IR 780 Perchlorate 
                 780 nm 
                 804 nm 
               
               
                   
                 (Dye 56) 
               
               
                   
                 IR 786 Iodide 
                 775 nm 
                 797 nm 
               
               
                   
                 (Dye 57) 
               
               
                   
                 IR 768 Perchlorate 
                 770 nm 
                 796 nm 
               
               
                   
                 (Dye 58) 
               
               
                   
                 IR 792 Perchlorate 
                 792 nm 
                 822 nm 
               
               
                   
                 (Dye 59) 
               
               
                   
                 1,1′-DIOCTADECYL- 
                 645 nm 
                 665 nm 
               
               
                   
                 3,3,3′,3′- 
               
               
                   
                 TETRAMETHYLINDODI- 
               
               
                   
                 CARBOCYANINE IODIDE 
               
               
                   
                 (Dye 231) 
               
               
                   
                 1,1′-DIOCTADECYL- 
                 748 nm 
                 780 nm 
               
               
                   
                 3,3,3′,3′- 
               
               
                   
                 TETRAMETHYLINDO 
               
               
                   
                 TRICARBOCYANINE IODIDE 
               
               
                   
                 (Dye 232) 
               
               
                   
                 1,1′,3,3,3′,3′- 
                 638 nm 
                 658 nm 
               
               
                   
                 HEXAMETHYL- 
               
               
                   
                 INDODICARBOCYANINE 
               
               
                   
                 IODIDE 
               
               
                   
                 (Dye 233) 
               
               
                   
                 DTP 
                 800 nm 
                 848 nm 
               
               
                   
                 (Dye 239) 
               
               
                   
                 HITC Iodide 
                 742 nm 
                 774 nm 
               
               
                   
                 (Dye 240) 
               
               
                   
                 IR P302 
                 740 nm 
                 781 nm 
               
               
                   
                 (Dye 242) 
               
               
                   
                 DTTC Iodide 
                 755 nm 
                 788 nm 
               
               
                   
                 (Dye 245) 
               
               
                   
                 DOTC Iodide 
                 690 nm 
                 718 nm 
               
               
                   
                 (Dye 246) 
               
               
                   
                 IR-125 
                 790 nm 
                 813 nm 
               
               
                   
                 (Dye 247) 
               
               
                   
                 IR-144 
                 750 nm 
                 834 nm 
               
               
                   
                 (Dye 248) 
               
               
                   
                   
               
             
          
         
       
     
         [0057]    This invention provides a solution to the problem of poor security marker signal response due to substrate optical interferences. Improved optical reading is accomplished by physical separation of a transparent label laminate  2  containing the marker  7  from the rest of the label  1 . Once separated, the security-marked label laminate  2  is transferred to a non-interfering optical background surface  34 , and an appropriate device  40 ,  42  reads the information contained in the pattern  9 . An indication of authenticity is obtained in a manner which requires only very small quantities of marker material. 
         [0058]    The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention. 
       Parts List  
       [0000]    
       
           1  label 
           2  label laminate 
           3  transmissive sheet material 
           5  layer of adhesive 
           7  marker 
           9  pattern 
           11  label substrate 
           13  printed information 
           15  second layer of adhesive 
           17  surface 
           20  label 
           22  marker 
           23  second marker 
           25  label 
           27  marker 
           30  label 
           32  marker 
           34  background surface 
           36  incident light 
           38  emitted light 
           40  light source 
           42  reader 
           45   a  LED 
           45   b  LED 
           47  component holder 
           48  angled holes 
           50  hole