Abstract:
A paper pad having a three dimensional image is disclosed wherein the faces or sides of the pad comprise a plurality of paper sheet edges formed into three dimensional surfaces extending from the common planar surface of the side or indenting into said surface. According to one embodiment, the three dimensional surfaces are created through computer numeric controlled (CNC) carving of a compressed side of the paper pad to create an aesthetically pleasing, complex three dimensional design. According to another embodiment, a shaped die is applied to a compressed side of a paper pad under selected conditions of time, temperature, pressure and humidity to deboss a portion of the paper material and produce a three dimensional design in the surface of the compressed side.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority as a divisional of U.S. application Ser. No. 11/317,797, filed on Dec. 23, 2005, which claimed priority to U.S. Provisional Application 60/638,740, filed Dec. 23, 2004. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to paper pads, and more particularly to a method of shaping the sides of paper pads to create a complex three-dimensional or textured surface. 
         [0004]    2. Description of the Related Art 
         [0005]    The art of manufacturing paper pads is well known, as is decoration of the sides or edges of the pad&#39;s sheeted paper layers. Typically, the sheets of a paper pad are attached along a common edge e to keep all the paper sheets together in a cohesive unit for ease of handling. The attachment may be provided by an adhesive, such as elastic polymeric material. According to this method the adhesive is applied to a common edge of the sheets of the pad, such that individual sheets may readily be removed from the pad by pulling away from the adhesive material. According to another method known in the art, a stripe of repositionable adhesive may be applied to a portion of the underside of each sheet adjacent to one edge of the pad. The bond strength of the repositionable adhesive is sufficient to maintain the pad as a cohesive unit, but is not strong enough to prevent individual sheets from being removed from the pad. 
         [0006]    In either construction of a note pad, it is desirable to add decoration to the sides of the pad. This decoration may be for artistic or advertising purposes to enhance the appearance and value of the note pad. It is known to decorate the sides of a note pad by applying printing and/or color to a pad&#39;s planar side surface. Applying printing and/or color to a pad&#39;s unshaped sides, however, limits decorative options to those that can be depicted in a simple plane. In another decorative method disclosed in U.S. Pat. No. 6,494,981 to Chen, shaped dies or cutting blades are used to cut a side of a note pad&#39;s pages. Die-cutting, however, allows creation only of simple, non-complex designs, such as simple curves and a variety of angles. Die-cutting, however, cannot produce complex three-dimensional designs because it involves a linear cut, typically perpendicular to the note pad&#39;s top surface. In addition, the die that makes the cut to forms the pad&#39;s edge is a fixed shape and only useful in production of many copies of the same fixed shape. 
         [0007]    What is needed is a note pad having complex, three-dimensional decorations and a method of producing the same. What is also need is a method of forming three-dimensional designs on the sides of note pads that can be easily modified to produce multiple designs. What is also needed is a method of forming note pads with raised relief three-dimensional designs. 
       BRIEF SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a method of forming complex, three-dimensional decorations in the sides of paper pads. According to one embodiment of the present invention, a paper pad is compressed to form a stable, rigid and effectively solid surface on at least one side of the pad, then mechanical means are applied selectively to remove paper from the compressed side in much the same way as wood is carved or shaped. To provide for uniform design and expedited production, computer numeric controlled (CNC) milling devices can be used to shape the compressed side of the pad. CNC machines are used in simple milling such as two-axis relief of a material as in routing of wood or metal or in a complex relief that involves complex curves using more than two-axis orientations of the cutting tools. 
         [0009]    According to another embodiment of the present invention, a paper pad is compressed to form a stable, effectively solid surface on at least one side of the pad, then a die containing a reversed design is applied to the compressed surface, under controlled conditions of temperature, pressure and humidity, to deboss a portion of the compressed side and form a pattern that includes three-dimensional elements. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0010]    The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: 
           [0011]    The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: 
           [0012]      FIG. 1  is a perspective view of a pad having a three-dimensional design according to the present invention. 
           [0013]      FIG. 2  is an exploded perspective view of a pad before it is shaped according to the present invention. 
           [0014]      FIG. 3  is an exploded perspective view of an array of pads before they are shaped according to the present invention. 
           [0015]      FIG. 4  is a side elevation view of a pad being shaped according to an embodiment of the present invention. 
           [0016]      FIG. 5  is a side elevation view of a pad being shaped according to another embodiment of the present invention. 
           [0017]      FIG. 6   a  is a partial perspective view as would be seen if taken along line  6 - 6  of  FIG. 1 , without reference to any particular design, of a pad according to an embodiment of the invention. 
           [0018]      FIG. 6   b  is a partial perspective view as would be seen if taken along line  6 - 6  of  FIG. 1 , without reference to any particular design, of a pad according to another embodiment of the invention. 
           [0019]      FIG. 6   c  is a partial perspective view as would be seen if taken along line  6 - 6  of  FIG. 1 , without reference to any particular design, of a pad according to another embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring now to the drawings, wherein like reference numerals refer to like parts throughout, there is seen in  FIG. 1  a shaped paper pad  10  according to the present invention. The pad has a top surface  12 , bottom surface  14  and sides  16 . As is known in the art, adhesive may be applied to retain the individual paper sheets of pad  10 . According to the present invention, a three-dimensional design  18  is formed in at least one side  16  of pad  10 . 
         [0021]    Referring now to  FIG. 2 , according to the present invention a pad  10  is provided, comprised of a plurality of individual paper sheets. Pad  10  is compressed between clamps  20 ,  22  so that compressed side  16   a  forms a stable, rigid and effectively solid surface. Preferably, clamps  20 ,  22  are at slightly less than the height of pad  10  and are positioned such that their edge is slightly below edge  16   a . As a minimum, clamps  20 ,  22  must provide sufficient pressure that the compressed side  16   a  forms a stable, rigid and effectively solid surface. The compressed paper surface lends itself as an ideal wood fiber tooling material in that it has no discernible grain or imperfections that could cause unwanted splintering or cracking that can occur when tooling actual wood. 
         [0022]    As shown in  FIG. 3 , according to one embodiment a plurality of pads  10  are compressed at one time between clamps  20 ,  22 . This permits multiple pads  10  to be shaped at the same time, increasing the efficiency of production. Because the pressure applied by clamps  20 ,  22  forms an effectively solid surface, it generally is not necessary to provide support below the pads  10  or along their lateral edges. 
         [0023]    Referring now to  FIGS. 4 and 5 , after pads  10  are compressed between clamps  20 ,  22  a variety of shaping techniques can be applied to produce a complex, three dimensional design on side  16   a . According to one embodiment, paper material is removed from side  16   a  by a cutting tool  24 . Acceptable cutting tools  24  include any tool used to shape wood. Preferably, cutting tool  24  is a rotary cutting tool such as a router. Using cutting tool  24  it is possible to form a relief pattern that includes complex three-dimensional shapes by selectively removing paper material from side  16   a . Preferably, cutting element  26  of cutting tool  24  should be extremely sharp to avoid producing a ragged edge. Operation parameters for cutting tool  24 , such as rotation speed, depth of cut and rate of cutting element  26  travel are similar to parameters used to shape wood. 
         [0024]    According to the preferred embodiment, the selective removal of paper material from side  16   a  is accomplished through programmable control of the movement of cutting tool  24 , for example by use of a CNC device  28 . By programming the computer to create a tooled or carved surface, paper may be cut or ground away to form a design  18  comprised of desired image or indicia. Use of a repeatable program makes it possible for the cutting tool  24  to consistently reproduce multiple, high-quality copies of a desired design  18 . In addition, using currently available CNC programming techniques, it is possible to generate an image of the desired design  18  on a computer, which then generates the required commands that cause the CNC device to produce the desired design  18  on side  16   a . Because of the accuracy of the CNC control process, the intricacy of the design  18  applied according to this embodiment is limited only by the size of the cutting element  26  of cutting tool  24 . 
         [0025]    If desired, side  16   a  can be shaped by multiple passes of cutting tool  24 . For example, the CNC device  28  can be programmed to cause cutting tool  24  to make a first pass (or series of passes) to remove large quantities of paper material from selected portions of side  16   a  using a large cutting element  26  and then to make a second pass (or series of passes) to shape a more intricate design in selected portions of side  16   a  using a smaller cutting element  26 . 
         [0026]    After the pad edges are tooled, the pad is still a functional writing material because the majority of the paper layer face is still intact. The individual sheet edges will be slightly irregular if the carving penetrates only a short distance into the original dimensions of the pad  10 . Preferably, paper material is removed to a depth of no more than 25% of the depth of pad  10 . 
         [0027]    According to the present invention, it is possible to shape some or all of the sides  16  of pad  10 . In a pad  10  in which the sheets of the pad are held together by repositionable adhesive applied to a portion of one surface of each sheet, typically along its edge, the side  16  adjacent the repositionable adhesive can be shaped according to the present invention. The repositionable adhesive in the material being shaped typically results in a smooth, aesthetically pleasing appearance. When shaping a side  16   a  containing repositionable adhesive, it is important to control the depth of the design  18  so that each sheet retains a sufficient amount of repositionable adhesive to be functional as a repositionable sheet. 
         [0028]    According to this embodiment of the invention it is possible to produce a pad  10  in which the image  18  is carved into the surface of side  16   a  as shown in  FIG. 6   a . Alternately it is possible to produce a pad  10  in which the image  18  appears to project from the surface of side  16   a  as shown in  FIG. 6   b.    
         [0029]    According to another embodiment of the invention, after the sides of pad  10  have been compressed, a three dimensional design  18  can be formed in side  16   a  by application of a debossing die  30 . While it is known in the art to create three dimensional images in paper by embossing (male and female die) and debossing (using a single die), these techniques have heretofore been applied to produce a three-dimensional image on the surface of a sheet of paper. An alternate embodiment of applicant&#39;s invention uses the technique of debossing to produce a three-dimensional image on a side  16   a  of a pad  10 . 
         [0030]    According to this embodiment, a pad  10  is compressed as previously disclosed. After the pad is compressed, a die  30  is pressed against side  16   a  of pad  10  to produce a three dimensional image. Typically, die  30  is a metal plate that has been tooled with an image. According to this embodiment, the image tooled into die  30  is a reverse of the image desired for the side  16   a  of pad  10 . Preferably, the depth of the image  18  should not exceed 2 millimeters. Deeper tooling causes the edges of adjacent paper sheets to “weld” together and makes it difficult to remove individual sheets from pad  10 . Die depths in the sub-micron range produce aesthetically pleasing patterns, especially when used in conjunction with a foil  32 , as described in more detail below. Preferably the die  30  will be applied to side  16   a  using controlled force such as a mechanical press, pneumatic press, hydraulic press, electric press or other similar device. In addition to selecting a die  30  having a proper depth, it also is possible to select the length of the press stroke to control the depth of the debossed image produced by the die  30 . 
         [0031]    According to the present invention, die  30  is pressed against pad  10  under controlled conditions of temperature, pressure, depth and humidity. A three dimensional design  18  according to the present invention is produced in a pad  10  having typical moisture content of 4 6%, by forcing a heated die  30  against side  16   a . Preferably, die  30  is heated to a temperature of at least 250° F., and preferable a temperature between 285° and 400° F. Typically, the die  30  should be applied to side  16   a  for a dwell time of 1 to 5 seconds, but the dwell time can be varied inversely with the temperature of the die  30 . For example, similar results can be achieved with a dwell time of 3 seconds at 285° when compared with a dwell time of 1 second at 400° F. Higher die  30  temperatures increase the rate of debossing, but also increase the risk that paper fibers at the edges of adjacent sheets will felt together and prevent easy removal of single sheets from the paper pad  10 . 
         [0032]    Applicant has achieved satisfactory results using a die  30  having surface area of approximately 9 square inches forced by a pneumatic press driving a 2″ diameter ram under 40-80 psi. Those skilled in the art will recognize that other methods of applying pressure can be substituted for an air press and that the specific conditions of heat, time and temperature can be modified to achieve similar results. For example, larger or smaller dies can be used to apply a three dimensional pattern or design over larger or smaller areas. 
         [0033]    The present invention also includes the addition of foil material  32  to the debossed image or design. Without foil material  32 , debossing according to the present invention produces an aesthetically pleasing three dimensional design  18 . Addition of foil material  32 , however, increases the aesthetic appeal of the three dimensional design  18 . According to this embodiment, foil material  32  in sheet form is placed between die  30  and side  16   a  before the die  30  is pressed against side  16   a . When pressure is applied to side  16   a  by die  30 , the foil material  32  is forced into the three-dimensional design  18  by die  30 . Generally, foil material  32  is forced against and adheres to side  16   a  at those locations where die  30  produces the deepest impression on side  16   a . After debossing, excess foil material  32  is removed, leaving only the portion of foil material  32  that adheres to the deepest projections of die  30 , as shown in  FIG. 6   c.    
         [0034]    According to the present invention, a debossed image according to this embodiment can be applied to some or all of the sides  16  of pad  10 . For a pad  10  in which the sheets of the pad  10  are held together by repositionable adhesive applied to a portion of one surface of each sheet, typically along an edge, the side  16  adjacent the repositionable adhesive can be debossed according to the present invention. 
         [0035]    While there has been illustrated and described what are at present considered to be preferred and alternate embodiments of the present invention, it should be understood and appreciated that modifications may be made by those skilled in the art and that the appended claims encompass all such modifications that fall within the full spirit and scope of the present invention.