Abstract:
Promotional codes are printed using thermochromic inks in a manner that conceals the codes until a beverage or other article is cooled sufficiently to reveal the codes.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Application No. 61/889,447 filed Oct. 10, 2013, and is a continuation-in-part of International Application No. PCT/US2012/051941 filed Aug. 22, 2012 which claims priority to U.S. Provisional Application No. 61/526,211 filed Aug. 22, 2011. 
     
    
     BACKGROUND 
       [0002]    Printed articles of manufacture may contain hidden codes or other indicia that may be used to redeem promotional materials or other valuable things. By way of example, a state lottery may be conducted using printed cards that utilize a plasticized ink to cover an area of the card stating a cash amount that may be revealed by scratching off the plasticized ink. A bottled soft drink may be sealed with a crown, the inside of which contains a promotional code that is redeemed by use of the Internet. A candy bar wrapper may also have an interior surface bearing this type of code, which is revealed only after the candy bar is unwrapped. Promotional indicia may be printed on bars of soap as taught in U.S. Pat. No. 7,743,704. 
         [0003]    Thermochromic inks are not generally regarded as being useful in the variable printing of promotional or other codes. This is because thermochromic inks contain thermochromic pigments in the form of microcapsules that are typically melamine-formaldehyde microcapsules, for example, as taught by U.S. Pat. No. 5,591,255 issued to Small et al., which is hereby incorporated by reference to the same extent as though fully replicated herein. These microcapsules range in size with particle diameters from 0.5 to fifteen microns. These particle sizes may not work well with individually configurable printing systems, such as ink jet printing. 
       SUMMARY 
       [0004]    The present disclosure overcomes the problems outlined above and advances the art by providing methods and apparatus for variable printing of promotional or other codes using thermochromic inks. 
         [0005]    In one embodiment, label is provided that supports variable printing of codes using thermochromic ink. A background may be printed using a background ink having a first color. A thermochromic ink is printed to overlay the background ink, and there is adopted a means for concealing a code that is revealed when the thermochromic ink undergoes a color transition. This means may be, for example according to one embodiment, a code printed over the background ink, the code being printed with an ink that matches the background ink. The thermochromic ink is colorless at room temperature and exhibits a color change upon sufficient cooling to reveal the code. 
         [0006]    In one embodiment, the means for concealing may be a code printed in thermochromic ink over the background ink. The code is printed with an ink that is colorless at room temperature and exhibits a color change upon sufficient cooling to reveal the code. 
         [0007]    In one embodiment according to these instrumentalities, a label is provided to supports use of variable printing of matrix codes using thermochromic ink. A first matrix code is printed using a first thermochromic ink that is colorless until cooled to a first predetermined temperature which renders the first matrix code visible in a first color. A second matrix code printed using a second thermochromic ink that provides a second matrix code when cooled to a second predetermined temperature which renders the second matrix code visible in a second color. The first thermochromic ink and the second thermochromic ink are clear at normal room temperature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  shows a system for variable printing of thermochromic codes according to one embodiment; 
           [0009]      FIG. 2  shows a label that has been partially printed using the system of  FIG. 1 ; 
           [0010]      FIG. 3  shows a label that has been completely printed using the system of  FIG. 1 ; 
           [0011]      FIG. 4  shows the label of  FIG. 3  adhered to a beverage bottle; 
           [0012]      FIG. 5  shows a label in successive stages of printing according to a laser ablation embodiment; 
           [0013]      FIG. 6  shows a label in successive stages of printing according to an ink overlay embodiment; 
           [0014]      FIG. 7  shows a label in successive stages of printing according to an ink overlay embodiment, where  FIG. 7A  shows an expanded portion thereof; 
           [0015]      FIGS. 8A and 8B  show a label in successive stages of printing according to a two dimensional matrix overlay embodiment. 
           [0016]      FIG. 9  is a plot showing a rate of color change versus temperature in a conventional thermochromic ink. 
           [0017]      FIG. 10  is a plot showing a rate of color change versus temperature in a conventional thermochromic memory ink. 
           [0018]      FIG. 11  shows a patch that may be printed on a beverage can, label or packaging to provide thermochromic functionality of indicia according to one embodiment. 
           [0019]      FIG. 12  shows a patch that may be printed on a beverage can, label or packaging to provide reveal functionality of indicia according to one embodiment. 
           [0020]      FIG. 13  shows a patch that may be printed on a beverage can, label or packaging to provide reveal functionality of indicia according to one embodiment. 
           [0021]      FIG. 14  shows a patch that may be printed on a beverage can, label or packaging to provide reveal functionality of indicia according to one embodiment.  FIG. 13  shows a patch that may be printed on a beverage can, label or packaging to provide reveal functionality of indicia according to one embodiment. 
           [0022]      FIG. 15  shows a patch that may be printed on a beverage can, label or packaging to provide reveal functionality of indicia according to one embodiment. 
           [0023]      FIG. 16  shows beverage cans as they may appear differently due to the functionalities of thermochromic and photochromic materials combined for printing on a single can. 
           [0024]      FIG. 17  shows a beverage can as it may appear differently due to the functionalities of thermochromic and photochromic materials combined for printing on a single can. 
           [0025]      FIG. 18  shows a beverage can as it may appear differently due to the functionalities of thermochromic and photochromic materials combined for printing on a single can. 
           [0026]      FIG. 19  shows a bottle crown as it may appear differently due to the functionalities of thermochromic and photochromic materials combined for printing on a single crown. 
           [0027]      FIG. 20  shows a level indicator printed as a pilsner glass that combines thermochromic and photochromic materials. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    System  100  contains a roll  102  of material that is continuously unrolled to form a web  104 . The web  104  may be, for example, paper or plastic material adhered to a release layer from which may be produced selectively detachable adhesive labels, or a sheet of aluminum. Print stations  106 ,  108  apply ink to the passing web  104 . Print station  110  is for rotogravure printing as is known in the art. A laser station  112  is positioned for operations on the printed web  104 . An optional platen assembly  114 ,  116  is positioned for vertical strokes  118  to cut selected portions of the web  104  into detachable labels (not shown). The printed web  104  is rolled into a demountable spool  120  for later use. A programmable computer  122  governs operations of system  100 . 
         [0029]      FIG. 2  shows a label  200  that contains surface  202  with indicia including a promotional code  204  in area  206 . The promotional code  204  may be printed using thermochromic ink of any color, such as thermochromic ink that may be purchased on commercial order from Chromatic Technologies, Inc. of Colorado Springs, Colo. The area  206  may be left unprinted with ink or may be covered with ink that differs from the thermochromic ink of code  204 . The promotional code  204  and any ink optionally placed in area  206  may be printed, for example, using print head  106  (see  FIG. 1 ). As shown in  FIG. 3 , the area  206  and the code  204  (not shown) have been covered by ink  300 , as applied by print station  108  (See  FIG. 1 ). The print station  110  has applied additional ink to form indicia  302 ,  304 . The indicia  304  optionally provides instructions for use of the promotional code  204  at print station  110 , such as “Chill to Reveal.”  FIG. 4  shows the label  200  applied to a bottle  400 . 
         [0030]    The sequence of printing on area  206 , the promotional code  204  and the ink  300  may be provided in any combination. For example, in one embodiment, neither the ink on area  206  or the ink  300  are required. In one embodiment, indicia on the label  200  may consist only of the promotional code  204  and the top coat of ink  300 . 
         [0031]    The spool  120  shown in  FIG. 1  may contain a plurality of such labels  200 , each bearing a different promotional code  204  as directed by the programming of computer  122  (see  FIG. 2 ). The labels may be detached from spool  120  and applied to the bottles by automated equipment as is well known in the art. The spool  120  is not essential and the web  104  run for direct use at any downstream process. 
       Laser Ablation 
       [0032]    The promotional code  204  may be formed using laser ablation. One solution is to perform laser ablation of the ink. By way of example, screen printing may be used to cover entirely the area  206  of  FIG. 2  with a band of thermochromic ink that is colorless when warm and which exhibits a color change when chilled. This color change may be, for example, from clear to blue. The laser station  112  ablates unwanted portions of ink in area  206  to leave the promotional code  204  using the methodologies reported, for example, in United States Patent Publication No. US 2009/0128860 to Graushar et al., which is incorporated by reference to the same extent as though fully replicated herein. The laser wavelength, pulsing frequency and applied power may be tuned to accommodate a particular thermochromic inks. While some of the ‘clear’ thermochromic inks used in this application are undetectable, other inks may leave a residue that is slightly visible. In these circumstances the top coat  300  (see  FIG. 3 ) may be used to hide this residue. 
         [0033]    In one embodiment, the area  206  may be screen printed with a colored ink, such as a white ink, and topcoated with a thermochromic ink that is clear at normal room temperature. The thermochromic ink may be laser ablated to form code  204  while leaving intact the ink over area  206 . The thermochromic ink forming code  204  changes color when chilled to a predetermined temperature to contrast with the in on area  206 , for example, forming the code  204  in blue on the white background of area  206 . Ink  300  may seal or protect the code  204  and cover any ascertainable differences, such as a change in glossiness that might otherwise reveal code  204  to the naked eye even before the label is cooled to the predetermined color transition temperature. 
         [0034]    In another example,  FIG. 5  shows a label  500  at different stages of printing,  502  ( FIG. 5A ),  506  ( FIG. 5B) and 508  ( FIG. 5C ). A background area  504  is printed at stage  502 . This background may be, for example, a white or gray background. A thermochromic band  508  may be printed at stage  506  and laser ablated at stage  510  to form promotional code  512 . 
         [0000]    Direct Print over Thermochromic Band with Matching Background 
         [0035]    A thermochromic pigment is prepared as taught in U.S. Pat. No. 5,591,255, except the pigment is screened to eliminate larger particle sizes. By way of example, the pigment may be centrifuged to separate particles by density gradient, and/or passed through a polyester or nylon screen, such as those obtainable on commercial order from Miami Aqua-culture of Boynton-Beach Fla., or any other source of micron screens known to the art. The screening may eliminate particles of over a certain size, such as by eliminating particles over a size that would be problematic to ink jet printing. Generally, this should eliminate particles over about 5 microns in diameter. Preferably, the particles have a size less than 3 microns and this is most preferably less than 1 micron. The screened pigment may then be used as pigment in a conventional formulation for ink jet ink, for example, as taught in U.S. Pat. No. 5,207,824 issued to Moffatt et al., which is hereby incorporated by reference to the same extent though fully replicated herein. In preparing the ink, care is taken to select ingredients from the list of optional ingredients in Moffat et al. so as to avoid use of aldehydes, ketones, and diols, and most aromatic compounds. The ink so prepared may be used in the system  100  for ink jet printing of thermochromic inks. 
         [0036]      FIG. 6  shows a label  600  at various stages  602 ,  604 ,  606  of printing. At stage  602 , background ink  608  is printed, such as a white background. Stage  604  entails printing a thermochromic band  610  over the background ink  608  by screen printing or, alternatively, ink jet printing using the ink described above. A promotional code  612  is printed over the thermochromic band  610  using the same ink used as the background ink  608 . The thermochromic band  610  is colorless at normal room temperature and changes color when cooled to a predetermined temperature. This predetermined temperature may be, for example, temperature of 5° C. indicating that a beverage has cooled to an optimum temperature to enhance organoleptic properties of a beverage. The color transition renders the code  612  visible to the naked eye, as the code  612  contrasts with the thermochromic band  610 . This color transition of the thermochromic band  610  may be, for example, from clear to blue. The promotional code  612  is optionally topcoated with a clear coating  614  to hide differences in glossiness between the background ink  608  and code  612 . 
         [0000]    Direct Print over Thermochromic Band with Matching Colors 
         [0037]      FIG. 7  shows a label  700  at various stages  702 ,  704  of printing. At stage  702 , a thermochromic background ink  706  is printed. At stage  706 , a promotional code  708  is printed. The ink used to print the promotional code matches exactly the color of the thermochromic background ink  706  at normal room temperature, such as matching burgundy colors. The thermochromic background ink  706  changes color when chilled to a predetermined temperature, for example, transitioning from burgundy to blue. As shown in the expanded view of  FIG. 7A , the promotional code  708  may be cross-hatched with thermochromic ink to hide slight differences between the background ink  708  and the thermochromic ink used to make the promotional code  708 . 
       Matrix Code 
       [0038]      FIG. 8A  is a first two dimensional matrix code  800  that may be printed as a label  802  using a first thermochromic ink that is clear at normal room temperature and transitions to a visible color, such as orange, upon being cooled to a first predetermined temperature. The label  802  is printed with a second thermochromic ink having a color transition temperature lower than the first predetermined temperature. The second thermochromic ink has, for example, transitions from clear to a color, such as black, to revel a second matrix code  804 . Thus, the label  802  is provided with a first matrix code  800  that may be revealed when a beverage is chilled to a state of being refrigerator code, and another matrix code  804  when the beverage is chilled to being freezer cold. The matrix codes  800 ,  804  may be scanned using, for example, an iPhone application and transmitted to a central server for processing according to promotional contest rules. 
       Hidden Images 
       [0039]    Hidden images, codes or messages may also be printed using a plurality of thermochromic inks, for example, to provide multiple messaging functionality.  FIG. 9  shows the rate of color change (delta pleni chroma) in a conventional thermochromic pigment as may be incorporated in a thermochromic ink. A cooling curve  900  shows a point  902  of full color development at about 8° C. Thus, as the pigment cools it develops a full color, such as a blue color, at 8° C. When the pigment warms, as demonstrated by warming curve  904 , point  906  represents a clearing point where the pigment loses its color, transitioning to clear. A gap  908  between the full color point  902  and the clearing point  906  is relatively narrow at approximately 4° C. 
         [0040]      FIG. 10  shows the performance of a second thermochromic pigment having a wider gap between cooling and warming curves. A cooling curve  1000  shows a point  1002  of full color development at about 8° C. Thus, as the pigment cools it develops a full color, such as a blue color, at 8° C. When the pigment warms, as demonstrated by warming curve  1004 , point  1006  represents a clearing point where the pigment loses its color, transitioning to clear. A gap  1008  between the full color point  902  and the clearing point  906  is relatively broad at approximately 11° C. The broadness of this separation makes the pigment suitable for use in what the industry refers to as wide hysteresis ‘memory inks.’ As used herein, a “memory ink” is a thermochromic in that has a clearing point and a full color point such that the difference between the clearing point and the full color point is greater than 4° C. This difference is preferably from 6-10° C. and is most preferably greater than 10° C. A “standard thermochromic ink” is one where the difference between the clearing point and the full color point and the clearing point is equal to or less than 4° C. 
         [0041]    Thermochromic pigments like those represented in  FIGS. 9 and 10  may be purchased on commercial order from such manufacturers as Chromatic Technologies, Inc. of Colorado Springs, Colo. It will be appreciated that the respective pigments represented in  FIGS. 9 and 10  may use the same leuco dye and the same developer to achieve the exact shade of color development between the two pigments. The internal phase or solvent carrying the dye and developer may be varied as a matter of design choice to affect the size of gaps  908 ,  1008 , as well as the specific temperatures of full color points  902 ,  1002 , and the clearing points  906 ,  1006 . A comparison of  FIGS. 9 and 10  confirms that the full color points  902 ,  1002  coincide at approximately 8° C., which means that the pigment of  FIG. 9  and that of  FIG. 10  will achieve full color at approximately the same time and temperature. However, upon warming, the pigment of  FIG. 9  transitions to clear at approximately 12° C. while the pigment of  FIG. 10  is a ‘memory ink’ that retains its color out to approximately 19° C. This creates a situation where the two pigments may be used alone or in combination to present indicia that displays upon warming in the interval from 12° C. to 19° C. 
         [0042]      FIG. 11  shows a multiple thermochromic patch  1100  where indicia  1102  is printed using a first ink or coating that contains a first thermochromic pigment having a full color point of 8° C. and a clearing point of 25° C. A background ink  1104  is a standard thermochromic ink that contains a first thermo chromic pigment having a full color point of 8° C. and a clearing point of 12° C. The background ink  1104  may be printed over an optional base coating  1106 . Optionally also, a second indicia  1108  may printed over the base coating  1106  and beneath the background ink  1104 , which overcoats the base coating  1106  and the second indicia  1108 . The second indicia resides under the background ink  1104  and may be printed using a conventional non-thermochromic ink or a photochromic ink. It will be appreciated that the specific temperature points of 8° C., 12° C., and 25° may vary by design. 
         [0043]    The patch  1100  may be printed on a beverage can, label or packaging. Upon cooling to 8° C. where full color development is achieved, the patch  1100  appears as a solid color patch having no indicia, except that elements of the base coating  1106  may be visible. The background ink  1104  turns to clear at 12° C. when a beverage or other product is subjected to warming. Upon clearing of the background ink, the indicia  1108  is revealed to announce that the beverage should “RETURN TO FRIDGE.” The first ink constituting indicia  1102  stays blue as warming continues up to 25° C. at which point the first ink also disappears. 
         [0044]      FIG. 12  shows another embodiment including patch  1200  where a base ink  1202  utilizes conventional non-color-changing ink or, optionally, a photochromic ink. Indicia  1204  is made using a thermochromic ink, for example, with a full color point of 8° C. and a clearing point of 25° C. The base ink  1202  and the indicia  1204  appear as the same color when the temperature if above 25° C., but as contrasting colors such a blue on white when the indicia  1204  has developed full color. 
         [0045]    The patch  1200  may be printed on a beverage can, label or packaging. Cooling to 8° C. achieves full color development such that indicia  1204  appears on the base ink  1202 . Upon warming, where the color development is maintained in the range from 8° C. to 25° C. and the upper end of this range if above room temperature (approximately 21° C.) but is less than human body temperature, it is possible to touch the indicia  1204  for sufficient warming to occur such that the indicia  1204  disappears. Thus, also, the indicia  1102  of  FIG. 11  may be made to disappear by touching. 
         [0046]      FIG. 13  shows a multiple thermochromic patch  1300  where indicia  1302  is printed using a first ink or coating that contains a first thermochromic pigment having a full color point of 8° C. and a clearing point of 12° C. A background ink  1304  contains a first thermo chromic pigment having a full color point of 8° C. and a clearing point of 25° C. The background ink  1304  is printed around the indicia  1302  and may also be printed over an optional base coating  1306 . Optionally also, a second indicia  1308  may printed over the background ink  1306  The second indicia contrasts with the developed color of the background ink  1304 , resides under the background ink  1304  and may optionally be printed using a photochromic ink. 
         [0047]    The patch  1300  may be printed on a beverage can, label or packaging. Upon cooling to 8° C. where full color development is achieved, the patch  1300  appears as a solid color patch having no indicia, except that elements of the base coating  1306  may be visible. The indicia  1302  turns to clear at 12° C. when a beverage or other product is thereafter subjected to warming. Upon clearing of the indicia  1302 , the base coating  1306  is revealed to make the indicia  1302  readable to announce that the prize is a car. The background ink  1304  stays blue as warming continues up to 25° C. at which point the background ink also disappears. 
         [0048]    In the embodiment of  FIG. 14 , patch  1400  contains an indicia  1402  that is printed using a first thermochromic ink that transitions from purple to pink at a full color point of 8° C. The first thermochromic ink has a clearing point of 12° C. A background ink  1404  has a full color point of 8° C. and a clearing point of 25° C. Thus, a purple message “WIN” is revealed against a pink background as warming progresses above 8° C. to 25° C. The message changes blue upon further warming, for example, as may occur by the touch of a hand. The specific colors used, such as purple to pink and purple to blue, may vary by design so long as the first color of the two inks matches. Thin this case the first color is purple, which may vary by design, as may the transition from the first color to blue or pink. 
         [0049]    In the embodiment of  FIG. 15 , patch  1500  contains indicia  1502  which is printed using first ink that contains a photochromic pigment, and may optionally also contain a thermochromic pigment. A background ink or coating  1504  is a conventional ink, such as a blue, yellow or red ink, but may optionally also contain a thermochromic pigment. The first (photochromic) ink is normally clear indoors, but may be color-activated by exposure to sunlight. Thus, on a blue form of background ink  1504 , a photochromic activation to produce yellow on indicia  1504  displays the indicia  1504  as a blend of yellow and blue to impart a green hue to indicia  1502 . The photochromic material in indicia  1502  may be selected to provide different color transitions. Thus, a photochromic transition to red over a blue background causes indicia  1502  to appear as purple. Similarly, when the background ink  1504  is yellow, photo chromic activation of indicia  1502  to blue causes indicia  1502  to appear green. When the background ink  1504  is yellow, photo chromic activation of indicia  1502  to red causes indicia  1502  to appear orange. When the background ink  1504  is red, photo chromic activation of indicia  1502  to blue causes indicia  1502  to appear purple. When the background ink  1504  is red, photo chromic activation of indicia  1502  to yellow causes indicia  1502  to appear orange. 
         [0050]    It will be appreciated that thermochromic inks develop color over a temperature interval and there is no sharp transition as a switch where all color appears at once or disappears at once. The discussion above uses a delta-chroma analysis to define a particular temperature, but acknowledges that the transition of color occurs over a range of temperature, frequently 1-4° C., as an inherent property of thermochromic inks. In the discussion above where two thermochromic inks or pigments are used in combination and share a common full color point, this constitutes an especially preferred embodiment where the standard thermochromic ink and the ‘memory ink to turn on simultaneously. This prevents premature revelation of the hidden message, code or image. For many applications, it will be merely preferred to have the full color point of one pigment be within from 0° C. to 20° C. of the other. A range of from 0° C. to 4° C. is more preferred, and a difference of less than 1° C. is even more preferred. 
         [0051]      FIG. 16  shows various combinations of the foregoing instrumentalities. Cans  1600 ,  1602  are respectively printed with thermochromic indicia  1604 ,  1606  depicting a lime that is normally white but demonstrates thermochromic activity by turning green at temperatures below a target temperature, such as 34° F. When the cans are taken outdoors, direct sunlight activates photochromic dye materials that reveal additional limes  1608 , and additional strawberries  1610 . 
         [0052]    Similarly,  FIG. 17  shows can  1700  that has indicia depicting a lime  1702 . The lime is a first color, such as white at room temperature indoors. Chilling of the can to a target temperature, such as 34° C., may cause all or part of the lime  1702  to turn green. When taken outdoors into direct sunlight, the lime  1702  changes color and may use a photochromic effect to appear as a deeper green that is divided by yellow segments that appear only in the sun. 
         [0053]      FIG. 18  shows can  1800  that has indicia depicting a lime  1802 . The lime is a first color, such as white at room temperature indoors. Chilling of the can to a target temperature, such as 34° C., may cause all or part of the lime  1802  to turn green. When taken outdoors into direct sunlight, the lime  1802  changes color and may use a photochromic effect to appear as a deeper green that is divided by yellow segments that appear only in the sun. 
         [0054]      FIG. 18  shows can  1800  that has indicia depicting a lime  1802 . The lime is a first color, such as white at room temperature indoors. Chilling of the can to a target temperature, such as 34° C., may cause all or part of the lime  1802  to turn green. When taken outdoors into direct sunlight, the lime  1802  changes color and may use a photochromic effect to appear as a deeper green that is divided by yellow segments that appear only in the sun. 
         [0055]      FIG. 19  shows a crown  1900  that has indicia depicting a lime  1902  in different shades of grey. Chilling of the crown to a target temperature, such as 34° C., may cause all or part of the lime  1802  to turn yellow. When taken outdoors into direct sunlight, the lime  1902  changes color and may use a photochromic blue effect to appear green that is divided by yellow thermochromic segments that appear yellow in areas that are not mixed with photochromic dye. 
         [0056]      FIG. 20  shows a beverage can  2000  presenting indicia as a pilsner glass  2002  that is printed with thermochromic ink over a white background, or any other background color. Thus, the glass  2002  is normally white, but changes to a yellow color (or any other color change contrasting with the background) by thermochromic action once chilling occurs to a target temperature, such as 40° F. As the internal contents are consumed, the liquid level falls to an approximate level  2004 . Beneath level  2004 , area  2006  maintains the color yellow remains chilled by the internal contents. Above level  2004 , area  2008  is warmed by the air. This causes the yellow to fade to white. This may be combined with photochromic effects, such as changing the logo “ITS MILLER TIME” from red to green in direct sunlight. 
         [0057]    The foregoing discussion teaches by way of example and not by limitation. Those skilled in the art understand that what is claimed may be subjected to insubstantial changes without departing from the true scope and spirit of the invention. Accordingly, this inventors hereby state their intention to rely upon the Doctrine of Equivalents in protecting their rights in what is claimed.