Abstract:
A method of making an ink stamp includes providing a first porous structure having a top surface, a bottom surface and porous edges extending between the top and bottom surfaces, loading a first ink into the first porous structure, and providing a second porous structure having a top surface, a bottom surface and porous edges extending between the top and bottom surfaces. The method includes loading a second ink into the second porous structure, applying energy to one of the porous edges of the first porous structure to transform the porous edge to an edge having a non-porous surface, and assembling the first porous structure with the second porous structure so that the non-porous edge of the first porous structure is in direct contact with one of the porous edges of the second porous structure. The non-porous edge prevents the first ink from passing through the non-porous edge to the second porous structure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   The present application is a continuation of U.S. patent application Ser. No. 10/627,911, filed Jul. 25, 2003, which claims the benefit of U.S. Provisional Application No. 60/437,962, filed Jan. 3, 2003. 

   BACKGROUND OF THE INVENTION 
   The present invention generally relates to ink stamping devices useful for making ink impressions on items such as papers, envelopes and cardboard containers. More particularly, the present invention relates to a multi-color stamping device having two or more adjacent pre-inked marking structures containing different color inks, whereby at least one of the marking structures has a non-porous edge for preventing migration of ink between two adjacent marking structures. The present invention also relates to methods and devices for properly assembling a composite marking structure. 
   Hand stamps having pre-inked marking structures enable a user to create numerous impressions without introducing additional ink into the marking structure. The pre-inked marking structures have microscopic pores that allow the ink initially retained within the marking structure to escape at a controlled rate. One high quality, pre-inked hand stamp is manufactured and sold under the trademark ROYAL MARK by M&amp;R Marking Systems Inc. of Piscataway, N.J. These pre-inked hand stamps include marking structures made using a gel comprising a mixture of thermoplastic resin and ink, which is commonly referred to as a pre-mix. 
   There are a variety of methods for manufacturing microporous marking structures. In one method, the pre-mix, which includes a desired quantity of ink, is poured into a mold. The mold is then heated in a vulcanizer at a predetermined pressure and temperature for a selected period of time. When the pressure, temperature and time parameters have been satisfied, the marking structure is formed into a microporous slab. The marking structure is then removed from the mold and any excess ink in the structure is removed during a stabilizing process. The marking structure has a resilient microporous network that contains ink, which is released through protruding indicia of a molding when pressed against a surface to be marked. 
   Another well known method of manufacturing microporous marking structures includes initially forming a microporous structure that does not contain ink. Such microporous marking structures may be manufactured by sintering, salt-leaching or other methods. This type of microporous marking structure is impregnated with ink during a separate procedure which may involve immersing the microporous marking structure in an ink pool, subjecting the microporous marking structure and ink to a vacuum environment or other known methods. With this type of microporous marking structure, it is generally necessary to stabilize the structure, i.e. remove excess ink therefrom, prior to assembly of the marking structure on a hand stamp mount. 
   Another type of pre-inked stamp uses a microporous foam upon which an image is flash printed. One flash exposure system for manufacturing pre-inked hand stamps is described at M&amp;R Marking System Inc.&#39;s Website at www.mrmarking.com and is provided under the trademark ULTIMARK. In general, the ULTIMARK system comprises a computer controlled flash irradiation device which exposes select areas of foam text plates (i.e. marking structures that have been formulated to be used in pre-inked hand stamps) to a high energy light source for a period of time. A protective film is used to shield certain areas of the microporous foam so that the shielded areas are not exposed to the light source. The brief exposure to light causes the exposed surfaces of the text plate to melt creating substantially non-porous areas at the exterior surfaces of the microporous foam. The unexposed areas remain porous so that the microporous foam can be subsequently used as a marking structure in hand stamps. 
   In one particular embodiment of the ULTIMARK system, the flash-exposed pre-inked stamps are made by printing or imaging a positive or negative image on a transparent paper or plastic, and then placing that image on a transparent body of typically glass or plastic in between a light source and the microporous foam to be exposed. A clear protective sheet may be placed over the flash exposable microporous material and on top of a transparent indicia medium. An improved process for preparing a microporous material for flash exposure is disclosed in commonly assigned U.S. patent application Ser. No. 10/439,469, filed May 16, 2003, the disclosure of which is incorporated by reference herein. 
   There have been a number of efforts directed to producing ink stamps capable of printing in two or more colors. For example, U.S. Pat. No. 6,289,806 to Hirano discloses a stamp having an occlusion body with a continuous porous structure that is impregnated with two or more kinds of ink. The occlusion body includes a physical barrier that inhibits mingling of two or more kinds of ink. Although Hirano addresses the issue of color mingling, it requires the use of additional parts in the form of a physical barrier to suppress the mingling of colors. 
   U.S. Pat. No. 6,047,639 to Shih discloses a stamping set including at least one partition strip that separates an enclosed space into at least two rooms for separating ink of two different colors. Although the &#39;639 patent also addresses the issue of preventing color mingling, it also requires the use of an additional component, i.e. a partition strip. 
   U.S. Pat. No. 5,601,644 discloses a multi-color ink stamp pad, whereby a thin, aqueous-impermeable film is disposed between the pads for preventing color mingling. Thus, the &#39;644 patent also requires an additional part to prevent mixing of the different colored inks. 
   There have also been a number of efforts directed to simplifying assembly of hand stamps. For example, U.S. Pat. No. 3,988,987 to Ikura discloses a stamp frame having a vertical interlocking projection on one of its side surfaces, a vertical interlocking groove on the opposite side surface, and a holding member removably mountable over the stamp elements to prevent displacement of the stamp elements relative to one another. Although Ikura applies to ensuring proper assembly of a stamp device, it teaches a registration concept applied to a stamp frame rather than the stamp pad itself. As such, there is nothing in the disclosure indicating a registration concept on the adjacent portions of the marking structure to facilitate the assembly of marking structures on a hand stamp mount. 
   SUMMARY OF THE INVENTION 
   In accordance with certain preferred embodiments of the present invention, a hand stamp includes a first marking structure, such as a porous foam marking structure, having ink stored therein. The first marking structure has a front surface adapted to print a first ink onto an object, a rear surface and peripheral edges extending between the front and rear surfaces. The hand stamp may also include a second marking structure, such as a porous foam, having a front surface adapted to print a second ink onto an object, a rear surface and peripheral edges extending between the front and rear surfaces of the second marking structure. The first and second marking structures are preferably assembled together so that at least one of the edges of the first marking structure opposes at least one of the edges of the second marking structure. At least one of the opposing edges desirably has a non-porous surface for preventing migration of a first ink in the first marking structure with a second ink in the second marking structure. 
   In certain preferred embodiments, the first and second marking structures preferably comprise a microporous foam, whereby certain areas of the foam may be exposed to an energy source for generating exposed surfaces on the foam. The exposure to light causes the exposed surfaces of the microporous foam to melt creating substantially non-porous areas at the surface of the foam. The unexposed areas of the foam remain porous so that the stamped foam can subsequently be used as a marking structure in hand stamps capable of creating ink imprints. The ink in the marking structures preferably passes through the porous regions of the face surface to create an imprint. In other preferred embodiments, the first and second marking structures may comprise a mixture of thermoplastic resin and ink that are exposed to light or energy for creating a design including porous and non-porous areas. 
   The hand stamp of the present invention is preferably used to create prints made of two or more colors. In one preferred embodiment, the first ink in the first marking structure is a first color, such as blue, and the second ink in the second marking structure is a second color, such as red, that is different than the first color. 
   In certain preferred embodiments, at least one edge of the first or second marking structure has a non-porous surface. The ink may be introduced into the foam structure either before the images are exposed thereon, during image exposure or after image exposure. The ink may also be introduced either before, during or after the marking structures are cut from the foam sheets. 
   In other preferred embodiments of the present invention, a hand stamp includes a first marking structure having a front surface adapted to print ink onto an object, a rear surface and peripheral edges extending between the front and rear surfaces of the first marking structure, whereby at least one of the peripheral edges of the first marking structure has a first pattern. The hand stamp of this embodiment may also preferably include a second marking structure having a front surface adapted to print ink onto an object, a rear surface and peripheral edges extending between the front and rear surfaces of the second marking structure, whereby at least one of the peripheral edges of the second marking structure has a second pattern that matches the first pattern. The hand stamp is fabricated by assembling the first and second marking structures together with the first patterned peripheral edge of the first marking structure interlocking with the second patterned peripheral edge of the second marking structure so that the first and second marking structures can be assembled together in only one configuration. In this particular embodiment, the edges of the first and second marking structures may or may not be non-porous. Although the present invention is not limited by any particular theory of operation, it is believed that having opposing patterned edges that match one another will simplify the assembly process and prevent the first and second marking structures from being assembled in an incorrect configuration. 
   In other preferred embodiments, at least one of the interlocking first and second patterned peripheral edges has a non-porous surface for preventing ink migration between the first and second marking structures. In other preferred embodiments, the patterned peripheral edges of both marking structures are non-porous for preventing ink migration. In other preferred embodiments, the patterned peripheral edges of both marking structures are porous. 
   In certain preferred embodiments, the first marking structure carries an ink having a first color and the second marking structure carries an ink having a second color that is different than the first color. As such, the assembled stamp is capable of generating a print having two or more colors, with at least one non-porous edge preventing ink migration or mixing of the first and second inks. 
   In still other preferred embodiments of the present invention, a hand stamp includes a porous marking structure having a front surface adapted to print ink onto an object, a rear surface and peripheral edges extending between the front and rear surfaces. The porous marking structure desirably has a first region containing a first ink, a second region containing a second ink and a non-porous border extending through the marking structure for preventing the first and second inks from migrating into one another. As noted above, in this particular embodiment, the porous marking structure may include foam or may be made of a mixture of thermoplastic resin and ink. The first ink in the first region of the marking structure preferably has a first color and the second ink in the second region of the marking structure preferably has a second color that is different than the first color. These and other preferred embodiments of the present invention will be described in more detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a front view of a porous foam sheet for making marking structures, in accordance with certain preferred embodiments of the present invention. 
       FIG. 2  shows a top perspective view of the porous foam sheet of  FIG. 1 . 
       FIG. 3  shows a first foam sheet having a plurality of first marking structures formed therein and a second foam sheet having a plurality of second marking structures formed therein, in accordance with certain preferred embodiments of the present invention. 
       FIG. 4  shows the respective first and second foam sheets with a first marking structure removed from the first foam sheet and a second marking structure removed from the second foam sheet. 
       FIG. 5  shows the removed first and second marking structures of  FIG. 4  aligned with one another for assembly. 
       FIG. 6  shows a perspective view of a second marking structure including a non-porous edge, in accordance with certain preferred embodiments of the present invention. 
       FIG. 7  shows an edge view of the second marking structure of  FIG. 6 . 
       FIG. 8  shows a bottom plan view of the second marking structure of  FIGS. 6 and 7 . 
       FIG. 9  shows a magnified view of the first and second marking structures of  FIG. 5 . 
       FIG. 10  shows the first and second marking structures of  FIG. 9  assembled together to form a combined marking structure. 
       FIG. 11  shows a bottom view of first and second foam sheets having first and second marking structures formed therein, in accordance with certain preferred embodiments of the present invention. 
       FIG. 12  shows a combined marking structure assembled from a first marking structure removed from the first foam sheet of  FIG. 11  and a second marking structure removed from the second foam sheet of  FIG. 11 . 
       FIG. 13  shows a magnified view of the first and second marking structures of  FIG. 12 , prior to assembly. 
       FIG. 14  shows the first and second marking structures of  FIG. 13  after assembly into a combined marking structure. 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a microporous foam sheet  20  having a top surface  22 , a bottom surface  24  remote from the top surface  22 , and one or more peripheral edges  26  extending between top surface  22  and bottom surface  24 . In the particular microporous foam sheet  20  shown in  FIG. 1 , the sheet has four edges  26  extending between top surface  22  and bottom surface  24 . In other preferred embodiments, the sheet may have less than four, or more than four, edges. 
     FIG. 2  shows a perspective view of microporous foam sheet  20  including top surface  22 , bottom surface  24  and one or more peripheral edges  26  extending between top surface  22  and bottom surface  24 . 
   Referring to  FIG. 3 , a process may be used, such as that disclosed in commonly assigned U.S. Provisional Application 60/380,974 filed May 16, 2002, to form marking structures that may be loaded with ink for creating pre-inked hand stamps. In certain preferred embodiments, the microporous foam sheets of  FIGS. 1 and 2  are exposed to a flash irradiation device whereby energy from a light source exposes certain areas of the foam to the light for melting the surface of the foam so as to form a non-porous area at the exterior surface of the foam. The unexposed areas of the foam remain porous so that the marking devices can be subsequently used as marking structures in hand stamps for creating imprints on surfaces such as paper, envelopes and containers. As shown in  FIG. 3 , a first foam sheet  30  having images flash-printed thereon includes a top surface  32  having images printed thereon, a bottom, untreated surface  34  that remains substantially porous and peripheral edges  36  that extend between the top, substantially non-porous surface and the bottom, substantially porous surface  34 . A cutting device, such as a laser, may preferably be used for cutting a plurality of marking structures  38 A- 38 F. Each marking structure  38 A- 38 F of first foam sheet  30  is substantially similar to one another so that the first marking structures may be used as a first part of a hand stamp marking structure. Each marking structure  38  includes an edge  40  that defines a unique pattern for assembly with another marking structure, as will be described in more detail below. Each first marking structure  38 A- 38 F is preferably cut using a laser. As the laser cuts through the first foam sheet  30 , the edges of the individual marking structures  38 A- 38 F are preferably exposed to the energy of the laser for melting the edges of the first marking structures  38 . As a result, the edges are non-porous so that ink may not pass therethrough. Other cutting devices such as cutting knives, razors, dies, presses and water may also be used. In all of these other cutting methods, energy must be applied to at least one of the edges of the marking structures to form at least one non-porous edge. 
     FIG. 3  also shows a second foam sheet  42  having a top surface  44 , a bottom surface  46  and peripheral edges  48  extending between top surface  44  and bottom surface  46 . The second foam sheet  42  is treated in a similar fashion as described above with respect to first foam sheet  30 , so that top surface  44  is substantially non-porous, except for the flag design, and the bottom surface  46  is substantially porous. Second marking structures  50 A- 50 F are cut from the second foam sheet  42 . The second marking structures  50 A- 50 F are substantially similar to one another and include a unique pattern  52  preferably cut using a laser (or one of the other cutting devices listed above). As the laser cuts through the second marking structures  50 A- 50 F, the surface of the edges are melted for forming non-porous surfaces through which ink may not pass. 
   In order to create a marking structure for a hand stamp, one of the first marking structures  38  from the first foam sheet  30  is assembled with one of the second marking structures  50  from the second foam sheet  42 . The edge pattern  40  of the first marking structure  38  may be assembled with the edge pattern  52  of a second marking structure  50  in only one orientation. This is due to the unique patterns cut into the first and second marking structures  38 ,  50 . 
   In the particular embodiment shown in  FIG. 3 , the first and second marking structures  38 ,  50  contain different portions of an American flag. The first marking structure  38  contains the stripes  54  of the American flag, while the second marking structure  50  contains the field and staff portion  56  of the American flag. The unique edge patterns  40 ,  52  cut into the respective first and second marking structures  38 ,  50  ensure that the marking structures may only be assembled together in one configuration. This avoids improper assembly as has occurred in prior art hand stamp devices. Moreover, the non-porous edges of the first and second marking structures  38 ,  50  prevent ink migration between the two marking structures. 
   In certain preferred embodiments, the first marking structure  38  is loaded with red ink so that the stripes  54  of the flag are red and white (in non-porous areas) and the second marking structure  50  is loaded with blue ink so that the field  56  of the flag is blue. After the first and second marking structures  38 ,  50  are assembled together, it is desirable to prevent the red ink of the first marking structure  38  from mixing with the blue ink of the second marking structure  50 . As such, the non-porous edges extending between the first and second marking structures are highly desirable for avoiding mixing or migration of the ink. The non-porous edges also preclude the need for a third object, such a barrier or border, to be assembled between the two marking structures  38 ,  50 , thereby simplifying the assembly process and minimizing the number of parts needed for assembly. 
     FIG. 4  shows first foam sheet  30  having one of the first marking structures  38 A removed therefrom and second foam sheet  42  having one of the second marking structures  50 F removed therefrom. 
   Referring to  FIG. 5 , first marking structure  38 A has a non-porous edge  36 A with a pattern  40  formed therein. The patterned edge  36 A preferably has a number of projections and depressions, which appear substantially similar to the edge of a puzzle piece. The second marking structure  50 F has a non-porous edge  48  with a pattern  52  that matches the pattern  40  of first marking structure  38 A. As such, the projections of pattern  40  of first marking structure  38 A fit into the depressions of  52  of the pattern of the second marking structure  50 F, and the projections of pattern  52  of second marking structure  50 F fit into the depressions of pattern  40  of first marking structure  38 A. As a result, the first and second marking structures  38 A,  50 F may be assembled together like puzzle pieces. This ensures that the first and second marking structures  38 A,  50 F may be assembled together in only one configuration, thereby avoiding improper assembly of the two pieces. 
     FIG. 6  shows a perspective view of the second marking structure  50 F having the field and staff portions  56  of an American flag formed thereon. The second marking structure  50 F has a top surface  44  that is substantially non-porous, a bottom surface  46  that is substantially porous and that extends in a substantially parallel orientation with respect to top surface, and a peripheral edge  48  extending between top surface  44  and bottom surface  46 . As noted above, peripheral edge  48  includes at least one edge having a pattern  52  cut therein. The patterned edge  48  is substantially non-porous, so that the ink stored in the second marking structure  50 F does not migrate into a first marking structure (not shown) assembled with the second marking structure  50 F. In use, the top surface or front face  44  of second marking structure  50 F is pressed against a printable surface, such as paper, so that the ink stored in the second marking structure  50 F passes through the microporous holes at the field design  56  formed on the top surface  44 . The blue ink does not pass through the non-porous portion of the top surface  44 . 
     FIG. 7  shows a magnified view of non-porous edge  48  of second marking structure  50 F. 
     FIG. 8  shows a bottom plan view of second marking structure  50 F including substantially porous bottom surface  46  and edge  48  having pattern  52  cut therein. 
     FIG. 9  shows first marking structure  38 A placed adjacent second marking structure  50 F so that the marking structures may be assembled together to form a combined marking structure for attachment to a hand stamp. The pattern  52  of edge  48  confronts the pattern  40  of edge  36 A. 
   Referring to  FIG. 10 , the first marking structure  38 A and second marking structure  50 F are assembled together, whereby the patterned edges of the respective first and second marking structures  38 A,  50 F interlock with one another to form a unified marking structure  60 . As noted above, in this particular preferred embodiment, a red ink is stored in first marking structure  38 A and a blue ink is preferably stored in the second marking structure  50 F. The non-porous edges between the first and second marking structures  38 A,  50 F prevent the blue and red ink from migrating into one another. In certain preferred embodiments, only one of the interlocking edges must be non-porous, while the other interlocking edge may remain porous. In these particular preferred embodiments, only one non-porous edge is needed to prevent ink migration. The combined marking structure  60  of  FIG. 10  may then be assembled to a hand stamp mount by attaching the rear surface of the combined structure  60  with the mount, such as by using an adhesive. 
     FIGS. 11-14  show the rear surfaces of foam sheets having marking structures cut therein so that the interlocking patterned edges may be clearly seen.  FIG. 11  shows the rear surface of first foam sheet  30  having first marking structures  38  cut therein and second foam sheet  42  having second marking structures  50  cut therein. As noted above, the bottom or rear surfaces of the respective first and second foam sheets  30 ,  42  are not exposed to light so that the respective surfaces remain substantially porous. During manufacture of the first and second marking structures  38 ,  50 , an ink is introduced into the microporous foam body of the first and second marking structures  38 ,  50 . When the face surfaces of the respective marking structures are pressed against a printable surface, the ink in the marking structures passes through the porous regions of the face surfaces for printing on printable surfaces. 
   Referring to  FIGS. 11 and 12 , a first marking structure  38 A is removed from first foam sheet  30  and a second marking structure  50 F is removed from second foam sheet  42 . The patterned edges of the opposing first and second marking structures  30 A,  50 F are then assembled with one another whereby the opposing projections and depressions interlock with one another similar to puzzle pieces. As such, the first and second marking structures  30 A,  50 F may only be assembled together in one configuration. 
     FIG. 13  shows a magnified view of  FIG. 12  prior to assembling the first marking structure  30 A with the second marking structure  50 F. First marking structure  30 A has an edge  36 A with a unique pattern  40 . Second marking structure  50 F also has an edge  48  with a unique pattern  52  cut therein. The opposing patterns  40 ,  52  match with one another so that the first and second marking structures  30 A,  50 F may be assembled together in only one configuration, thereby preventing improper assembly of the first and second marking structures  30 A,  50 F with one another.  FIG. 14  shows first and second marking structures  30 A and  50 F assembled together. 
   Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.