Abstract:
A printer system including one or more printer rollers is capable of imprinting an identifiable texturing on print media. The identifiable texturing can be used to match print media from the printer system with the printer system. The printer system can imprint identifiable texturing that is not visible to the unaided eye. Therefore, a user of the printer system is unaware that the print medium can be matched with the printer system. The imprinting process is a relatively simple process in which the surface of the print medium is mechanically deformed. Therefore, expensive chemical analysis is not required to match the print medium with the printer system.

Description:
TECHNICAL FIELD  
         [0001]    The technical field is printer systems, particularly printer systems capable of imprinting identifiable texturing on print media.  
         BACKGROUND  
         [0002]    In order to enforce laws against counterfeiting operations, law enforcement agencies gather facts and evidence linking suspected counterfeiters to a counterfeiting crime. One form of evidence is to show that counterfeit print samples were created by printer systems belonging to the suspected counterfeiters. Law enforcement agencies use several methods to match counterfeit print samples of unknown origin with printer systems.  
           [0003]    One method of matching a print sample of unknown origin with a printer system involves deliberately modifying printer systems so that print samples contain a unique “fingerprint” of the printer system. For example, a printer system may imprint its fingerprint on a print sample by marking the print sample with a very light color. However, counterfeiters may avoid using a printer system having such a marking system because the light color marking may be detectable by the unaided eye.  
           [0004]    Chemical identification, or “chemical fingerprinting,” may also be used to match a print sample with a printer system. In chemical fingerprinting, chemicals of the ink contained in a print cartridge have a unique composition that is not detectable by the unaided eye. A counterfeit print sample can therefore be matched with a suspected printer system by comparing the ink on the print sample with the ink in the print cartridge used by the printer system. Chemical fingerprinting may be impractical, however, because of the high cost and complexity involved in the mass production of print cartridges with unique compositions of ink. Depending on the process used, the chemical analysis required to match a counterfeit print sample to a print cartridge may also be expensive. Additionally, chemical fingerprinting may be ineffective because counterfeiters would most likely use the print cartridges very quickly and discard them soon after use.  
           [0005]    Therefore, a need exists for a reliable and effective system and method for matching print media with a printer system that does not involve excessive cost or complexity.  
         SUMMARY  
         [0006]    According to a first aspect, a printer system can include one or more patterned printer rollers capable of imprinting an identifiable texturing on print media. The identifiable texturing can be used to match print media from the printer system with the printer system.  
           [0007]    According to the first aspect, the printer system can generate identifiable texturing that is not visible to the unaided eye. Therefore, a user of the printer system is unaware that a print medium can be matched with the printer system.  
           [0008]    Also according to the first aspect, the imprinting process is a relatively simple process in which the surface of a print medium is mechanically deformed. Therefore, expensive chemical analysis is not required to match the print medium with the printer system.  
           [0009]    Other aspects and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying figures. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0010]    The detailed description will refer to the following drawings, wherein like numerals refer to like elements, and wherein:  
         [0011]    [0011]FIG. 1 is a cross-sectional view of a printer system according to a first embodiment;  
         [0012]    [0012]FIG. 2A is a side view of a patterned printer roller having a patterned surface according to the first embodiment;  
         [0013]    [0013]FIG. 2B is a cross-sectional view of the patterned printer roller of FIG. 2A taken on line  2 B- 2 B;  
         [0014]    FIGS.  2 C- 2 G illustrate various patterns that may be formed in the patterned printer roller;  
         [0015]    [0015]FIG. 3 is a flow chart illustrating a method for imprinting an identifiable texturing on a print medium using a printer system having one or more patterned printer rollers;  
         [0016]    [0016]FIG. 4 is a flow chart illustrating a method for making a patterned printer roller using an impression mold process;  
         [0017]    FIGS.  5 A- 5 F illustrate a method for making the patterned printer roller according to the method illustrated in FIG. 4;  
         [0018]    [0018]FIG. 6 is a flow chart illustrating a method for making a patterned printer roller using a sandblasting process; and  
         [0019]    FIGS.  7 A- 7 C illustrate a method for making the patterned printer roller according to the method illustrated in FIG. 6. 
     
    
     DETAILED DESCRIPTION  
       [0020]    A printer system and method for imprinting identifiable texturing on print media will be discussed by way of preferred embodiments and by way of the figures.  
         [0021]    [0021]FIG. 1 illustrates a cross-sectional view of a printer system  100  having several printer rollers  105 . The printer system  100  also includes at least one patterned printer roller  200  having a patterned surface. The patterned printer roller  200  is used to imprint identifiable texturing on print media. The identifiable texturing can be used to match print media with the printer system  100 . The print media may be, for example, paper, cardboard, transparent film, fabric, laminated sheets, label stock and other types of printable media. The operation of the printer system  100  is discussed in detail below.  
         [0022]    In the printer system  100 , the printer rollers  105  may be, for example, conventional pinch rollers such as those used in conventional printer systems. The printer system  100  includes an entry  115 , a feed path  120 , a toner system  122  and an exit  125 . Print media  110  are loaded into the printer system  100  at the entry  115 , advanced along the feed path  120  by the printer rollers  105 , printed upon by toner system  122  and ejected at the exit  125 . The orientation of the feed path  120  inside the printer system  100  may be defined by the position of various additional internal components (not shown) of the printer system  100 . The printer system  100  may include one or more printer roller pairs  130  of opposed printer rollers  105 . Additionally, the printer system  100  may include a printer roller pair  130  that includes one or two opposed patterned printer rollers  200 . The printer rollers in each printer roller pair  130  are capable of rotating in unison with respect to each other. A printer roller pair  130  having one or two patterned printer rollers  200  may be located at one of various points along the feed path  120 , including, for example, near the entry  115  or the exit  125  of the printer system  100  or a location immediately before or after the toner system  122 .  
         [0023]    [0023]FIG. 2A is a side view of the patterned printer roller  200  having a patterned surface  202 . FIG. 2B is a cross-sectional view of the patterned printer roller  200  taken on line  2 B- 2 B in FIG. 2A. A patterned surface  202  of the patterned printer roller  200  creates an identifiable texturing on the print medium  110 , which can be used to match the print medium  110  with the printer system  100 . The patterning of the patterned surface  202  is exaggerated in FIG. 2B for illustrative purposes.  
         [0024]    The patterned printer roller  200  may comprise several components, including a cylindrically shaped core  205  wrapped by an outer layer  210  that conforms to the cylindrical shape of the core  205 . A metal collar  212  may be affixed to the ends of the patterned printer roller  200  to allow the patterned printer roller  200  to be attached to a shaft (not shown) that is rotated by a motor (not shown) in the printer system  100 . Alternatively, the shaft may be formed as a part of the patterned printer roller  200 . The other printer rollers  105  are also designed to be rotated on shafts by a motor in the printer system  100 . The outer layer  210  is patterned so that the print medium  110  is imprinted by the patterned surface  202  when the print medium  110  passes through a printer roller pair  130  including the patterned printer roller  200 . The core  205  and the outer layer  210  may be made of the same or different materials. The core  205  is preferably made of a rigid material. The outer layer  210  is preferably made of a high friction material, such as an elastomer or other similar material that enables gripping of various kinds of print media. Alternatively, the patterned printer roller  200  may comprise a single component made of, for example, synthetic rubber. In this embodiment, the outer surface of the patterned printer roller  200  is patterned. The other printer rollers  105  in the printer system  100  may be similar in construction to the patterned printer roller  200 , except that an outer layer  210  with a patterned surface  202  is not required.  
         [0025]    The print medium  110  is inserted into the printer system  100  at the entry  115 . The printer rollers  105  grip the print medium  110  at the entry  115  and pull the print medium  110  into the printer system  100 . The print medium  110  is then advanced through the printer system  100  by the printer rollers  105  along the paper feed path  120 . The print medium  110  undergoes a print process and is imprinted with an identifiable texturing by the patterned surface  202 . The motor in the printer system  100  rotates the patterned printer roller  200  about a longitudinal axis  215 . The printer rollers  105  in each printer roller pair  130  may also be rotated by motors. The print medium  110  is then ejected at an exit  125 .  
         [0026]    In FIG. 1, the printer system  100  includes one patterned printer roller  200 . However, opposed patterned printer rollers  200  may be included in a printer roller pair  130  so that identifiable texturing is imprinted on both sides of the print medium  110 . The patterned printer rollers  200  may grip the print medium  110  at opposite sides or in multiple places across the entire width of the print medium  110 , thereby imprinting identifiable texturing on opposite sides or at multiple places across the entire width of the print medium  110 , respectively.  
         [0027]    The identifiable texturing imprinted on the print medium  110  may be detected using one of several inspection methods. Once the texturing has been identified, the texturing may be matched with the printer system  100  having the patterned printer roller  200  that matches the texturing on the print medium  110 . Various methods for identifying texturing on print media may be used. In one example, the texturing imprinted by the patterned printer roller  200  may be detected using a stylus or optical surface roughness profilometer, such as is used in semiconductor wafer processing industries. When using a stylus profilometer, a stylus is moved along the surface of a textured print medium and the vertical motions of the stylus are measured and plotted to generate a topographic map. There are many other surface profiling techniques that may be used. In another example, a glancing incident photo reflection system may be used. In a glancing incident photo reflection system, light is projected onto a textured print medium at near glancing incident angles from a single direction, casting shadows in depressions that can be detected with a microscope and/or recorded with another light measuring device. Scanning the textured print medium and changing the direction of the light allows the pattern on the surface of the print medium to be topographically mapped.  
         [0028]    FIGS.  2 C- 2 G illustrate various patterns for the patterned surface  202  of the patterned printer roller  200 . In FIG. 2C, a regular pattern of projections, or “teeth”, of the patterned printer roller  200  would imprint a regular texturing pattern on a print medium. In FIGS.  2 D- 2 F, an irregular pattern of teeth of the patterned printer roller  200  imprints an irregular texturing pattern on a print medium. Additionally, the irregular pattern may include different shapes, including shapes that resemble a jigsaw puzzle.  
         [0029]    Referring to FIG. 2G, an irregular pattern of teeth of the patterned printer roller  200  may be used together with invisible ink or chemical tracers dispensed throughout the surface of the patterned printer roller  200 .  
         [0030]    The pattern formed on the outer layer  210  may be predetermined, including, for example, an identifiable repetitive pattern, or random, including, for example, an identifiable arbitrary pattern. Alternatively, the patterned surface  202  may include both predetermined and random pattern elements. A predetermined or random pattern of identifiable texturing may therefore be imprinted on the print medium  110 . A method for imprinting the print medium  110  is discussed below with reference to FIG. 3. The method is appropriate for imprinting both random and predetermined texturing on the print medium  110 .  
         [0031]    [0031]FIG. 3 is a flow chart  300  illustrating a method for imprinting an identifiable texturing on the print medium  110  using a printer system  100  having a patterned printer roller  200 . In step  305 , the print medium  110  is pulled into the printer system  100 . In step  307 , the print medium is advanced along the feed path  120 . In step  310 , the print medium  110  is printed upon by toner system  122  in the printer system  100 . In steps  305 - 310 , the print medium  110  undergoes a print process that is commonly used, for example, in ink jet or laser printer systems.  
         [0032]    In step  315 , the print medium  110  is gripped by the patterned printer roller  200  and moved tangentially and in contact with the patterned outer layer  210  of the patterned printer roller  200 . The patterned outer layer  210  imprints identifiable texturing on the face of the print medium  110  that is in contact with the patterned outer layer  210 . The identifiable texturing imprinted on the print medium  110  corresponds to the patterned surface  202 .  
         [0033]    In step  320 , the print medium  110  is ejected from the printer system  100  at the exit  125 . As an alternative to the above method, the print medium  110  may be imprinted with identifiable texturing before being printed upon.  
         [0034]    The printer system  100  may also include a printer roller pair  130  comprising two opposed patterned printer rollers  200 . In this case, in step  315 , the opposed patterned printer rollers  200  grip the print medium  110  simultaneously on both faces of the print medium  110 , and imprint identifiable texturing on both faces of the print medium  110 .  
         [0035]    [0035]FIG. 4 is a flow chart  400  illustrating a method for making the patterned printer roller  200 . FIGS.  5 A- 5 F illustrate the printer roller  200  at various states in the method. In this embodiment, the patterned surface  202  is formed by an impression mold process. A multi-component patterned printer roller  200  is discussed in the following description. However, the patterned printer roller  200  may be made of a single component or several components.  
         [0036]    Referring to FIGS. 5A and 5B, in step  405 , a stock printer roller  502  having a core  505  and outer layer  510  is formed. FIG. 5B is a cross-sectional view taken on line  5 B- 5 B in FIG. 5A. The external surface  512  of the outer layer  510  of the stock printer roller  502  is preferably smooth, with minimal indentations or impressions. As described above, the core  505  may be made of, for example, elastomer, and the outer layer  510  may be made of, for example, rubber. The core  505  and outer layer  510  of the stock printer roller  502  may be manufactured through various known processes such as, for example, injection molding or extrusion. The core  505  and outer layer  510  may be combined, for example, using an adhesive bonding process.  
         [0037]    Referring to FIG. 5C, in step  410 , the stock printer roller  502  is loaded into a carrier system  515  that guides and supports the stock printer roller  502  during the impression mold process. In step  415 , the stock printer roller  502  is preheated to a temperature that sufficiently softens the outer layer  510  so that indentations and/or projections can be formed into the outer layer  510 . The projections may resemble miniature teeth. The stock printer roller  502  may be heated by an external heat source  513 , or alternatively, heated from within the stock printer roller  502  by various known methods. Additionally, an impression mold board, described in detail below, may be heated before the impression mold board is put in contact with the stock printer roller  502 .  
         [0038]    [0038]FIG. 5D illustrates an impression mold board  520  used to form the pattern in the outer layer  510 . The impression mold board  520  has a surface  525  that is initially smooth having minimal indentations and/or projections. In step  420 , a mold pattern  530  is formed on the surface  525  of the impression mold board  520 . The impression mold board  520  may be formed of, for example, a metallic material. The mold pattern  530  may be formed, for example, by etching or impressing a pattern into the surface  525 , resulting in a mold pattern  530  of small indentations and/or projections  535  formed on the surface  525 . Impressing the mold pattern  530  may be performed by mechanical means, for example. Etching may be, for example, laser or chemical etching and may be performed by a computerized system. The mold pattern  530  is exaggerated in FIGS. 5D and 5E for illustrative purposes. The indentations and/or projections  535  may be of various sizes and shapes in order to produce a wide variety of mold patterns  530 .  
         [0039]    The mold pattern  530  may be predetermined or random. For a predetermined pattern, the etching process may be a computer-controlled process that produces the indentations and/or projections  535  on the surface  525  of the impression mold board  520 . The indentations and/or projections  535  may be etched into an identifiable repetitive pattern. For a random pattern, the etching process may be a computer-controlled process that incorporates a random number generator. The random number generator produces an identifiable arbitrary pattern of indentations and/or projections  535  on the surface  525  of the impression mold board  520 .  
         [0040]    Etching the indentations and/or projections  535  into the surface  525  of the impression mold board  520  results in a patterned impression mold board  520 . Referring to FIGS. 5E and 5F, in step  425 , a release agent  540  is applied to the patterned impression mold board  520 . The release agent  540  helps to reduce excessive adhesion between the outer layer  510  of the stock printer roller  502  and the mold pattern  530  as the stock printer roller  502  is rolled across the patterned impression mold board  520 .  
         [0041]    In step  430 , the stock printer roller  502  is rolled across the impression mold board  520 , and the mold pattern  530  formed on the surface  525  impresses the outer layer  510  of the stock printer roller  502 . The outer layer  510  is impressed with a pattern corresponding to the mold pattern  530  and the stock printer roller  502  is formed into a patterned printer roller  200 .  
         [0042]    In step  435 , the patterned printer roller  200  is cooled in order to fix the pattern on the outer layer  510 . In step  440 , the patterned printer roller  200  is removed from the carrier system  515 .  
         [0043]    One advantage of the above embodiment is that the patterned printer roller  200  may be formed to have a patterned surface that imprints identifiable texturing on a print medium that is not detectable to the unaided eye. This may be accomplished by using an etching process having a high resolution to create a very fine mold pattern  530  on the surface  525  of the impression mold board  520 . The high resolution pattern on the surface  525  therefore impresses a fine pattern on the surface of the stock printer roller  502 , so that the patterned printer roller  200  imprints a fine, identifiable texturing on print media. The identifiable texturing may be detected using various known inspection systems, such as a surface roughness profiler or a glancing incident photo reflection system as described above.  
         [0044]    Another advantage is that the patterned printer roller  200  may be formed to have a patterned surface that imprints identifiable texturing that is unique. For example, each mold pattern  530  may consist of a unique configuration of indentations and/or projections  535 . Therefore, each patterned printer roller  200  may have a unique patterned surface  202  that imprints unique texturing. Unique texturing ensures that the print medium  110  can be accurately matched to the printer system that produced the print medium  110 .  
         [0045]    As an alternative to the impression mold process described in FIG. 4, the patterned printer roller  200  may be formed by a direct etching process of the outer layer of a stock printer roller. The etching process may be a computer-controlled process that produces a pattern of indentations and/or projections directly on the surface of the outer layer.  
         [0046]    [0046]FIG. 6 is a flow chart  600  illustrating an alternative method for making the patterned printer roller  200 . In this embodiment, the patterned outer layer  210  is formed by a sandblasting process. A multi-component patterned printer roller  200  is discussed in the following description. However, the patterned printer roller  200  may be made of a single component or several components.  
         [0047]    Referring to FIGS. 7A and 7B, in step  605 , a stock printer roller  702  having a core  705  and outer layer  710  is formed. The core  705  and the outer layer  710  of the stock printer roller  702  may be manufactured through various known processes as described above. The stock printer roller  702  is manufactured so that the external surface  712  of the outer layer  710  is preferably smooth, containing minimal indentations or impressions.  
         [0048]    Referring to FIG. 7C, in step  610 , the stock printer roller  702  is loaded into a carrier system  715  that guides and supports the stock printer roller  702  during the sandblasting process. In step  615 , the outer layer  710  of the stock printer roller  702  is initially sandblasted with an abrasive material  720  to form a random pattern on the outer layer  710 . The abrasive material  720  may comprise particles of various sizes and shapes.  
         [0049]    After the initial sandblasting step  615 , the outer layer  710  is examined in step  620  to determine whether a desired roughness has been achieved. The desired roughness may be a roughness sufficient for forming a patterned surface on the outer layer  710  that is capable of imprinting an identifiable texturing on the print medium  110  that is preferably not detectable to the unaided eye. In step  625 , if the desired roughness has not been achieved by the initial sandblasting step  615 , further sandblasting is performed on the outer layer  710  until the desired roughness is achieved. A patterned printer roller  200  results from step  625 . The patterned printer roller  200  is removed from the carrier system  715  in step  630 .  
         [0050]    Due to the inherent random nature of the sandblasting process, the patterned surface formed on the outer layer  710  is statistically ensured to be unique. Therefore, each patterned printer roller  200  having a patterned surface  202  formed by the sandblasting process will imprint unique texturing on the print medium  110 . The random pattern on the patterned surface  202  can include indentations caused by the impact of the abrasive material on the stock printer roller  702 .  
         [0051]    Other methods that may be used to form a random pattern on the outer layer  710  of the stock printer roller  702  include laser ablation of the surface of the stock printer roller, impinging the surface of the stock printer roller with a water jet, etching the surface of the stock printer roller with acid and sputtering the surface of the stock printer roller.  
         [0052]    While the printer system has been described in connection with an exemplary embodiment, it will be understood that many modifications will be readily apparent to those skilled in the art, and this application is intended to cover any variations thereof.