Label for receiving indicia having variable spectral emissivity values

Labels that are conducive to the detection of bar-codes and other indicia having varying spectral emissivity values are provided. The labels include a substrate, a background layer, a thermally conductive layer and an adhesive layer. The background layer is preferably similar in visual appearance to the indicium that the label is to receive. Meanwhile, the thermally conductive layer is made from a material with high thermal conductivity that is used to substantially equalize the temperature across the label surface, thereby enabling a faster and cheaper detection of transitions of differential emissivity on the indicium surface. The adhesive layer is used for attaching the label to a document or other product.

BACKGROUND OF THE INVENTION

This invention relates to labels. More particularly, this invention relates to secure, machine readable labels that are conducive to the detection of bar-codes and other types of markings, or indicia, that have varying spectral emissivity values.

Various marking techniques have been used for identification and authentication purposes. For example, machine-readable codes (e.g., bar-codes) and other types of indicia have been used to attach important information to documents and other types of products such as clothing, accessories and the like. The information provided by these machine-readable codes has typically included the origin, authorship, history, ownership and/or other features of the product to which the code is attached. In the case of envelopes or packages to be mailed, for example, bar-codes have been used to provide evidence of proper postage paid. Meanwhile, for example, pricing information has been embedded in bar-codes used in the case of retail product labeling.

As protection against counterfeiting has become an increased concern, moreover, the use of various types of “invisible” marking techniques has became much more prevalent. For example, indicia that uses ultraviolet (UV) and infrared (IR) inks have become widely used. One benefit of using these types of inks is that they are typically not visible when illuminated with light in the visible spectrum (i.e., about 400-700 nm), but are visible when illuminated with light in the UV spectrum and IR spectrum, respectively. Thus, as with the other types of “invisible” indicia, an individual is unable to tell whether the product contains a security mark by merely looking at the product with the naked eye. Similarly, magnetic materials which are detected through their perturbation of a magnetic field have also been used.

Despite the early success of the above-described types of indicia, they have become more vulnerable to copying, alterations and counterfeiting as a result of technological advancements. For example, indicia using UV ink are easily detected through the interaction of the ink with radiation. In addition to mere detection, moreover, indicia using UV inks have proven to be susceptible to copying, alterations and counterfeiting (e.g., through the use of conventional office products).

An alternate type of indicium that is more related to the present invention is disclosed in commonly owned, co-pending U.S. patent application Ser. No. 10/355,670, filed Feb. 1, 2003, entitled “Information Encoding On Surfaces By Varying Spectral Emissivity,” which is hereby incorporated by reference in its entirety. This type of indicium is implemented by modifying a surface such that it has varying emissivity values, where emissivity is the ability of the given surface to emit radiant energy compared to that of a black body at the same temperature and with the same area. For example, at least two patterns that differ in spectral emissivity by known amounts are used to form a machine-readable code or other type of marking that can be detected (and/or decoded) through the use of a scanner (e.g., a laser spot scanner or an active laser pyrometer) that is capable of detecting emissivity differentials. In general, these patterns are preferably indistinguishable from their surroundings. Moreover, even when visible, the emissivity values of the patterns are not subject to duplication by standard office equipment. As such, they are less susceptible to counterfeiting, and can be used more reliably for identification and authentication purposes.

Current labels that may receive bar-codes or other types of markings (e.g., those types of markings described in U.S. patent application Ser. No. 10/355,670), however, are often not adequate. For example, the color and the patterns of the inks used in making a marking are often visible to the naked eye when applied to current labels. As such, it becomes extremely difficult to provide a document or other product with a hidden security marking.

Additionally, current labels are not designed to enable fast, accurate and cheap detection of transitions of differential emissivity for a marking that uses varying spectral emissivity values. For example, the presence of temperature variations along the surface of existing labels often makes the use of more expensive and time consuming scanning equipment necessary given that, in this case, measuring levels of radiated thermal energy alone may not be sufficient to obtain accurate measurements of emissivity values. Additionally, such temperature variations also increase the likelihood that the detection of transitions of differential emissivity will be subject to errors.

In view of the foregoing, it is an object of this invention to provide a machine readable label for receiving indicia having variable spectral emissivity values that alleviate the above and other problems associated with existing labels.

SUMMARY OF THE INVENTION

These and other objects of the present invention are accomplished in accordance with the principles of the present invention by providing a label that enables placement of hidden indicia having varying spectral emissivity values and that is conducive to the detection of transitions of differential emissivity.

The labels constructed in accordance with the principles of the present invention include a substrate, which can be either separately attached to, or a part of, the document or product to which the label is to be used with. Additionally, the labels also include a background layer and a thermally conductive layer. The background layer is preferably similar in visual appearance to the indicium that the label is to receive, such that the indicium is indistinguishable from the remainder of the label and/or the document or other product that the label is being used with.

The thermally conductive layer, meanwhile, is made from a material with high thermal conductivity, and is used to substantially equalize the temperature across the label surface. In this manner, the labels are resistant to temperature variations and thereby facilitate the faster and cheaper detection of transitions of differential emissivity on the indicium surface.

Moreover, in various embodiments of the present invention, the label includes an adhesive layer for attaching the label to a document or other product. Meanwhile, in other embodiments in which the substrate is a part of the document or the product, for example, the adhesive layer is not necessary.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a cross-sectional side view of one embodiment of a secure, machine readable label100constructed in accordance with the principles of the present invention. As explained in greater detail below, label100may be applied to a document or other product, and is adapted to receive and facilitate the detection of invisible (or visible) indicia having variable spectral emissivity values.

Label100includes substrate110, thermally conductive layer120, background layer130and adhesive layer140. Substrate110can be made, for example, from paper, plastic, tyvec, a metallic film or a metallic foil. Persons skilled in the art will appreciate, however, that substrate110can be made from any suitable material, and that the invention is not limited in this manner.

Substrate110can be either physically separate from, or integral to, the document or product to which label100is applied. For example, in various embodiments of the present invention, substrate110may be manufactured separately from the document or product(e.g., label110can be completely constructed prior to its application to a document or other product).

It is also contemplated that, in alternate embodiments of the present invention, substrate110of article100can be manufactured together with, or a part of, the document or product it is to be used with (in which case, as explained below, adhesive layer140may not be necessary). For example, the material from a paper document or a mail piece (e.g., a mailing envelope). may be used as the substrate of label100.

As described above, label100also includes thermally conductive layer120. Thermally conductive layer120can be made from, for example, a metallic foil or a layer of metallic ink. In a preferred embodiment, thermally conductive layer120includes a 0.5 mil adhesive-backed copper foil. It will nonetheless be understood that thermally conductive layer120can be made from any material with high thermal conductivity.

The purpose of thermally conductive layer120is to substantially equalize the temperature of label100across the surface of background layer130(or, when background layer130is not present, the surface of the applied indicium having variable spectral emissivity values). In particular, label100is intended to simplify the detection and scanning process of the indicium applied to label100by equalizing the temperature of the scanned area. Namely, by equalizing the surface temperature of label100, thermally conductive layer120ensures that apparent differences in surface temperature as detected by a pyrometer, or other thermal sensor arrangement, are in fact differences in thermal emissivity and therefore contain information that is intended to be conveyed by the indicium that is applied to label100.

Thermally conductive layer120can be applied in advance to substrate110. Alternatively, thermally conductive layer120can be applied just prior to, or substantially simultaneously with, the application of an indicium onto label100. For embodiments of the present invention in which thermally conductive layer120is applied substantially simultaneously with an indicium to substrate110, thermally conductive layer120can be, for example, a layer of ink with high metallic content. For example, thermally conductive layer120can be an ink with high copper content, which after drying preferably leaves a layer of 85% or more pure copper.

Moreover, persons skilled in the art will appreciate that, although thermally conductive layer120is shown to reside on top of substrate110inFIG. 1, the invention is not limited in this manner. In particular, thermally conductive layer120can also be applied below substrate110(e.g., between substrate110and adhesive layer140, if present). Additionally, when transparent, thermally conductive layer120can be located on top of background layer130(if present), or alternatively, on top of the printed indicium (not shown inFIG. 1). An example of this embodiment of the present invention would be an indium-tin-oxide ink layer placed on top of background layer130, or on top of (or around the boundary of) the indicium applied to label100.

It is also contemplated that thermally conductive layer120be excluded from label100in various embodiments of the present invention. For example, when label100receives indicia having relatively large emissivity differentials, the need for a substantially equalized surface temperature is reduced. In these cases, or in cases where substrate120provides adequate equalization of surface temperature, for example, thermally conductive layer120may not be necessary. Additionally, thermally conductive layer120can also be incorporated into background layer130(which is described below) by using a material that has both the desired thermal and optical properties.

As described above and shown inFIG. 1, label100further includes background layer130. In various embodiments of the present invention, the indicium applied to label100is situated on top of background layer130. For this reason, background layer130preferably has a visual appearance that is identical to, or at least substantially similar to, that of the indicium that is applied to label100. In this manner, the optical properties of background layer130can prevent the applied indicium from being recognized or observed by the naked eye. Namely, the applied indicia and background layer130appear to the eye as a featureless area of uniform color and appearance with no discernable features.

It will be understood that, in various embodiments of the present invention, background layer130may be excluded. For example, in cases where the applied indicium has similar optical properties to substrate120, background layer130may not be necessary to “hide” the indicium. Furthermore, it is also contemplated that label100receives an indicium that remains resistant to both copying and alteration by standard office equipment, but that is nonetheless recognizable by a casual observer (e.g., when label100is designed to serve as an overt deterrent to counterfeiting).

As is the case with thermally conductive layer120, background layer130can be integral to substrate110(e.g., background layer130can be manufactured together with, or a part of, substrate110). Moreover, background layer130can be applied well in advance, just before, or substantially simultaneously with the application of the indicium onto label100. Background layer130can also be applied around the edges (and/or in between any open gaps) of the applied indicium in accordance with the principles of the present invention, rather than underneath it.

Finally, as shown inFIG. 1, label100includes adhesive layer140. Adhesive layer140can be any suitable type of material that can be used to affix label100to a document or other product. For example, adhesive layer140can be a gum or pressure sensitive glue backing. Moreover, adhesive layer140can have a peel off plastic layer (not shown) that is removed immediately prior to the application of label100to the surface of a document or other product.

Instead of being applied to the surface of a document or other product, for example, label100can also be integrated into (i.e., manufactured as part of) the document or other product with which it is to be used. In this case, adhesive layer140may not be necessary. Additionally, it will be understood that, even when label100is not integrated into the receiving document or product, label100may be applied by some means other than adhesive layer140. For example, label100may be sewn to the document or other product that it is to be used with, or attached by any other suitable method. The invention is not limited in this manner.

FIG. 2is a cross-sectional side view of label100to which indicium250is applied (e.g., printed) in accordance with the principles of the present invention. It will be understood that, although indicium250is applied on top of background layer130in the embodiment of the present invention shown inFIG. 1, this is not mandatory. For example, as explained above, thermally conductive layer120can be located on top of indicium250. The invention is not limited in this manner.

As shown inFIG. 2, indicium250includes a pattern of areas of varying emissivity251and252. Although a particular pattern is shown inFIG. 2, persons skilled in the art will appreciate that indicium250may take the form of any suitable bar code (e.g., code 39 or PDF-417) or other machine readable code. Moreover, it should also be appreciated that indicium250does not necessarily include a machine-readable code, and may, for example, also include a human readable character or symbol.

To achieve patterns251and252, indicium250uses two or more inks which preferably has a different spectral emissivity value than background layer130, although this is not mandatory. The inks may be, for example, a black colored carbon-black ink and a black colored inorganic ink (preferably ink jet printing is used for both inks). In a preferred embodiment, indicium250is printed with a hot melt inkjet printing system and contains, for example, code 39 bar-code information. However, printing may be accomplished through any suitable method, including offset, ink jet, xerographic or press.

The inks used to make indicium250may be composed of, for example, a suitable carrier liquid containing a suspension, solution, or other composition of pigments and other materials of known spectral emissivity in either the total electromagnetic spectrum, or in a given portion of the spectrum. Carrier liquids may be based on water or hydrocarbon, including liquids such as alcohol, ethylene glycol, or others known in the ark of ink making. Furthermore, examples of materials with known emissivity values that are readily adapted to conventional printing processes include carbon, cobalt, copper, gold, manganese and silver.

Additionally, in accordance with the principles of the present invention, the inks used for indicium250preferably have the same or very similar visual appearance (e.g., apparent brightness, color and texture) as that of background layer130. In this manner, indicium250is invisible to the naked eye, but readable by means of a scanner that is capable of detecting transitions of differential emissivity. Moreover, even if indicium250is visible to the naked eye, and/or capable of being copied by standard office equipment and scanners, the information contained in the variable emissivity code will not be so readable or capable of being copied. In particular, while copying a label100that uses a visible indicium250by conventional office equipment may appear to achieve the result of a copy that is similar to the original, the copy will nonetheless lack the required transitions of differential emissivity to maintain the information (or symbol) of indicium250.

It will be understood that the inks used for providing indicium250can be printed or applied in any suitable manner to label100. For example, these inks can be printed in complementary patterns in a single pass, such that the whole area of the mark is covered with one or the other ink. Alternatively, for example, a first ink can be printed over the whole area, allowed to dry, and then a second ink can be printed in the pattern on top of the first ink. Regardless of the manner of application, in a preferred embodiment, the indicium appears to be a solid pattern (e.g., a solid black marking) in the visible spectrum, but reveals pattern in a selected invisible range in which the two inks have a known emissivity differential.

It should also be understood that it is not mandatory for indicium250to be continuous across the surface of background layer130. For example, indicium250may includes gaps, or spaces, in between the areas of varying emissivity251and252. In this case, for example, the emissivity value of background layer130can be used as part of the pattern (i.e., to add additional transitions of differential emissivity). Moreover, it will also be understood that indicium250may include only a single ink, in which case the emissivity value of background layer130could be used in conjunction with the emissivity value of indicium250to form the pattern of varying emissivity. The invention is not limited in this manner.

FIG. 3is a top-view of the label shown inFIG. 2which better illustrates the varying emissivity values of indicium250as detectable by a suitable scanner. As can be seen fromFIG. 3, label100also includes an optional brand identification marking360that can be applied to label100. It will be understood that marking360can be applied to any suitable location (e.g., on top of thermally conductive layer120if present) and in any suitable manner (e.g., by using an adhesive layer similar to adhesive layer140, or being integral to label100). Marking360provides visible writing that, for example, identifies the manufacturer of label100to an observer of label100. Alternatively, mark360may identify the manufacturer of the document or product for which label100is being used. Persons skilled in the art will appreciate that the invention is not limited by the location or information content of marking360, which may or may not be present in various embodiments of the present invention.

FIG. 4is a top-view of the label shown inFIG. 2which illustrates the visible appearance of the label to a naked eye. In particular, as shown inFIG. 4, background layer130and indicium250appear to be a featureless area of uniform color and appearance with no discernable features. In this manner, whether it is a bar-code or other type of mark or symbol, indicium250will not be observable by the naked eye. In fact, the presence of any marking at all will likely not be known by an observer who is unfamiliar with the technology of the present invention.

It will be appreciated that, when “hiding” the presence of indicium250is not a concern, label100can be constructed such a naked eye can detect the patterns of indicium250. Accordingly, in various embodiments of the present invention, for example, it is possible that background layer130and indicium250will not appear to be a featureless area of uniform color, but rather, have discernable features that serve to deter counterfeiters of a product.

Unlike indicium250of label100described above, however, indicium550of label500shown inFIG. 5makes use of varying emissivity values as influenced by surface texture. In particular, the outermost layer (e.g., a background layer as described above) of label500is imprinted to create indicium550having areas of varying surface roughness551and552. These areas can be created in any suitable manner. For example, areas551and552can be created by embossing with an electromechanical dot matrix printer (e.g., the Epson MX-80). This can be done without ink, as shown inFIG. 5, or, as explained below, with ink formulated to fix and retain the surface texture. Alternatively, raised printing can be created by means of high resolution ink jet printing which can print areas of varying dot density patterns using an ink formulated for raised lettering as known in the art. Optionally, a label with a metallic film surface can be embossed with different textures for this embodiment of the invention. It will be understood that while indicium550is shown to be located at the top layer of label500, the invention is not limited in this manner.

Instead of imprinting indicium550, an alternate composition of the special inks described above can also be used in accordance with the principles of the present invention to create areas of varying surface roughness. For example, inks that dry or cure with a predetermined surface texture can be used in order to create a surface of predetermined transitions of differential emissivity. Such inks include, for example, those that comprise dense suspensions of colorants, pigments, or other particulate materials such as ferric oxide.

In addition, a combination of the methods used in connection with labels100and500is also possible. For example, the surface of a label according to the invention may be embossed or physically textured before inking, or an ink may be embossed after drying to produce a desired emissivity.

FIG. 6shows a mailing envelope670that uses a label100according to the principles of the present invention for the purpose of providing postage paid or other information. It will be understood by persons skilled in the art that another label according to the invention (e.g., label500) can also be used with envelope670without departing from the spirit of the present invention.

In one embodiment, the indicium (not shown in detail) of label100shown inFIG. 6may include a machine-readable code that is used, for example, as a postage meter indicium which simply contains information relating to funds paid for postage or other relevant information. In other embodiments, information pertaining to the originating address of the sender, the time and date of sending, and/or other pertinent information may be included in the indicium. Alternatively, for example, the indicium of label100shown inFIG. 6may serve as a “signature” mark, or symbol, that is designed to authenticate the identity of the individual or corporation sending the letter. In this case, it is contemplated that such a “signature” mark may be provided alone or in combination with postage paid or other relevant information. The invention is not limited by the particular information found in the indicium of label100used with mailing envelope670.

Persons skilled in the art will appreciate that label100may be attached to envelope670in any suitable manner. For example, if label100includes an adhesive layer140, then adhesive layer140can be used to attach label100to envelop670. Alternatively, a glue or other type of adhesive can simply be applied to the bottom of label100immediately prior to its application to envelope670. In yet other embodiments of the invention, label100may be constructed integral to envelope670. For example, it is contemplated that envelopes be mass produced having labels100integrated into the envelope material. In this case, for example, each envelope can be sold with a pre-paid postage indicium that permits a user to mail the envelope via first class mail for up to a predetermined weight. Moreover, it is also possible for the various layers of a label100or500to be applied individually to envelope670, at any time during or after the production of envelope670. The invention is not limited in this manner.

FIG. 7shows a carrying bag780that uses a label100for authentication or other purposes according to the principles of the present invention. It will be understood that label100shown inFIG. 7(which could be replaced with a label500without departing from the spirit of the invention) may include any suitable information (e.g., purchase price, manufacturer information, etc.).

Label100can be located in any suitable place on the surface (or in the interior) of bag780. For example, label100can be placed in an overt manner, such that counterfeiting may be deterred. In other embodiments, label100can be located such that label100is not readily observable (in which case the anticipation of a “hidden” label by potential counterfeiters may serve as an equally effective deterrent). Moreover, label100can be applied to bag780in any suitable manner. As with label100ofFIG. 6, for example, label100ofFIG. 7may be applied to bag780using adhesive layer140(if present), by being sewn onto bag780or constructed integral to bag780. It will also be understood that it is possible for the various layers of a label100or500to be applied individually to bag780, at any time during or after the production of bag780

Persons skilled in the art will appreciate that the labels described above in accordance with the principles of the present invention are provided as illustrations of the invention only, and that the invention is not limited by the specific configurations described above. For example, while labels100and500use specific types of indicium250and550, respectively, the invention is not limited in this manner. Rather, any suitable indicium (e.g., whether created using inks, areas of varying surface textures, or other means) may be used in conjunction with the labels described herein without departing from the spirit of the present invention. Additionally, while certain uses for labels100and500are described above, other uses are also within the scope of the invention. These other uses may include, for example, providing hidden coding of driver's licenses to distinguish authentic licenses from counterfeits, hospital identification tags and the like.

Moreover, it will also be understood by those skilled in the art that the various layers of a label according to the invention may be manufactured together, allowing the label to be applied as a single item to a document or other product. However, as explained above, it is also contemplated that some or all of these layers be applied individually to a document or other product, and that in certain embodiments, some of these layers be excluded (or combined with other layers). The invention is not limited in this manner.

The above described embodiments of the present invention are presented for purposes of illustration and not of limitation, and the present invention is limited only by the claims which follow.