Patent Publication Number: US-8539867-B2

Title: Perforator

Description:
The present application is a divisional application of co-pending U.S. patent application Ser. No. 11/173,535 filed on Jul. 1, 2005 by Wade A. Powell, Scott K. Carter, Jr., Mark McDonnell and entitled PERFORATOR, the full disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND 
     Perforations are sometimes formed in a medium to facilitate removal of portions of the medium or for other purposes. Existing devices for perforating a medium may be expensive and may be difficult to adjust. In addition, such devices also may be noisy, difficult to use, and space consuming. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a perforator system in an open state according to one exemplary embodiment. 
         FIG. 2  schematically illustrates the perforator system of  FIG. 1  in a first perforating state according to one exemplary embodiment. 
         FIG. 3  schematically illustrates the perforator system of  FIG. 1  in a second perforating state according to one exemplary embodiment. 
         FIG. 4  illustrates different perforation patterns according to one exemplary embodiment. 
         FIG. 5  schematically illustrates another embodiment of the perforator system of  FIG. 1  incorporated into an imaging system according to one exemplary embodiment. 
         FIG. 6  schematically illustrates another embodiment of the perforator system of  FIG. 1  incorporated into an add-on module for use with an imaging system according to one exemplary embodiment. 
         FIG. 7  schematically illustrates another embodiment of the perforator system of  FIG. 1  configured as an add-on module for use with an imaging system according to one exemplary embodiment. 
         FIG. 8  is a top perspective view of an embodiment of the perforator system of  FIG. 7  according to one exemplary embodiment. 
         FIG. 9  is a front perspective view of the perforator system of  FIG. 8  with portions removed for purposes of illustration according to one exemplary embodiment. 
         FIG. 10  is a rear perspective view of the perforator system of  FIG. 8  with portions removed for purposes of illustration according to one exemplary embodiment. 
         FIG. 11  is a side elevational view of the perforator system of  FIG. 8  in open state with portions removed for purposes of illustration according to one exemplary embodiment. 
         FIG. 12  is a side elevational view of the perforator system of  FIG. 8  in a perforating state with portions removed for purposes of illustration according to one exemplary embodiment. 
         FIG. 12A  is a greatly enlarged view of the perforator system of  FIG. 12  taken along line  12 A- 12 A according to one exemplary embodiment. 
         FIG. 13  is a partially exploded perspective view of another embodiment of the perforator system of  FIG. 1  according to one exemplary embodiment. 
         FIG. 14  is a side elevational view of the perforator system of  FIG. 13  in an open state according to one exemplary embodiment. 
         FIG. 15  is a side elevational view of the perforator system of  FIG. 13  in a perforating state according to one exemplary embodiment. 
         FIG. 16  is a side elevational view of the perforator system of  FIG. 13  in a perforating state according to one exemplary embodiment. 
         FIG. 17  is a side elevational view of the perforator system of  FIG. 13  in a perforating state according to one exemplary embodiment. 
         FIG. 18  is a side elevational view of the perforator system of  FIG. 13  in a perforating state according to one exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  schematically illustrates perforator system  20  which is configured to selectively form perforations in a sheet of media  22  having a first face  24  and a second opposite face  26 . Perforator system  20  generally includes media feed  30 , perforator components  32 ,  34 , torque source  36  and controller  42 . Media feed  30  comprises a mechanism configured to move media  22  along a media path  44  between perforator components  32  and  34 . In an open state of system  20 , media feed  30  moves media  22  between components  32  and  34  while components  32  and  34  are substantially stationary. In a perforating state of system  20 , media feed  30  moves or drives media  22  between components  32  and  34  while components  32  and  34  are rotating and engage media  22 . In one embodiment, media feed  30  may comprise one or more rollers configured to engage media  22 . In other embodiments, media feed  30  may comprise other media engaging structures such as belts, webs and the like. 
     Perforator components  32  and  34  comprise individual components configured to cooperate with one another to form one or more perforations in media  22 . Perforator component  32  includes rotatable member  48 , blades  50 A,  50 B (collectively referred to as blades  50 ) and anvils  52 A,  52 B (collectively referred to as anvils  52 ). In some embodiments, each of blades  50 A,  50 B may comprise a set of discrete blades, knives, or pins arranged in a substantially linear fashion to cut small holes or otherwise weaken the media  22  along a line perpendicular to the directions indicated by arrows  72 . Each of the anvils  52 A,  52 B may comprise a structure having holes that are sized and arranged to permit corresponding ones of the blades, knives, or pins of the blades  50 A,  50 B to at least partially engage the holes to perforate the media  22 . Perforator component  34  is similar to perforator component  32  and includes rotatable member  58 , blades  60 A,  60 B (collectively referred to as blades  60 ) and anvils  62 A,  62 B (collectively referred to as anvils  62 ). Rotatable members  48  and  58  comprise structures configured for rotation about axes  54  and  64 , respectively, which extend generally parallel to one another. Rotatable member  48  supports blades  50  and anvils  52 . Rotatable member  58  supports blades  60  and anvils  62 . In the particular example illustrated, rotatable members  48  and  58  comprise elongate cylindrical members. In other embodiments, rotatable members  48  and  58  may have other configurations. For example, in other embodiments, support members  48  and  58  may have polygonal cross-sectional shapes. 
     Blades  50  and blades  60  comprise structures configured to cooperate with anvils  62  and  52 , respectively, to form one or more perforations in media  22 . In the particular embodiment illustrated, blades  50  engage face  24  while anvils  62  engage face  26  of sheet  22  during perforating. Blades  60  engage face  26  while anvils  52  engage face  24  of media  22  during perforating. 
     Blades  50  and blades  60  may comprise series of elongate structures providing multiple axially spaced points configured to form a line of apertures or indentations in media  22  (i.e., a perforation). Blades  50  and blades  60  are configured in some embodiments to at least partially pierce or perforate media  22 . 
     Anvils  52  and anvils  62  generally comprise structures coupled to rotatable members  48  and  58 , respectively, configured to cooperate with blades  60  and blades  50 , respectively, to form perforations in media  22 . Anvils  52  and anvils  62  generally comprise structures that are resiliently compressible or resiliently compliant such that blades  60  and blades  50  may depress and pierce media  22  against and into anvils  52  and anvils  62  respectively. In one embodiment, anvils  52  and anvils  62  each include a series of holes to receive portions of blades  50 ,  60 , respectively. In other embodiments, anvils  52  and anvils  62  may be formed from resilient materials and may have configurations other than that shown. 
     As further shown by  FIG. 1 , blades  50  and anvils  52  of perforator component  32  are angularly spaced from one another about axis  54  and blades  60  and anvils  62  are angularly spaced from one another about axis  64  by a sufficient degree such that perforator components  32  and  34  may be rotated to position blades  50  and  60  sufficiently apart from one another on opposite sides of media  22  and to position anvils  52  and  62  sufficiently apart from one another on opposite sides of media  22  to allow media  22  to pass between perforator components  32  and  34  without being perforated. In the particular example shown, the distance between axes  54 ,  64  and the outer most points of blades  50  and anvils  52  and blades  60  and anvils  62 , respectively, as well as the angular spacing between blades  50  and anvils  52  and blades  60  and anvils  62  is such that media  22  may be passed between perforator components  32  and  34  while remaining in a plane or substantially linear media path  44 . 
     In the particular example illustrated, rotatable members  48  and  58  each have a diameter of about 22 millimeters, each of blades  50  and  60  project from rotatable members  48  and  58  by a distance of about 1.7 millimeters and each of anvils  52  and  62  project from members  48  and  58  by a distance of about 1.7 millimeters. Axes  54  and  64  are spaced from one another by a distance of about 25.4 millimeters (1 inch). As a result, media path  44  may extend in a plane between perforator components  32  and  34  and perpendicular to axes  54  and  64  while accommodating media  22  having a thickness of up to about 3.4 millimeters. In other embodiments, the dimensions of rotatable member  48  and  58  as well as angular spacings between blades  50 ,  60  and anvils  52 ,  62 , respectively, may be varied depending upon the thickness of media  22  to be accommodated while still permitting media  22  to pass between perforator components  32  and  34  relative to perforator components  32  and  34  without being perforated. 
     In the particular example shown in  FIG. 1 , blades  50 ,  60  and anvils  52 ,  62  are angularly spaced from one another so as to also reduce the degree by which rotatable members  48  and  58  are rotated to perforate media  22 . In the particular example shown in which blades  50 ,  60  and anvils  52 ,  62  are angularly spaced from one another by about 90 degrees, rotation of members  48  and  58  through a maximum angle of 90 degrees results in media  22  being perforated into face  24  or alternatively into face  26 . From the open position shown in  FIG. 1 , components  48  and  50  are rotated 45 degrees in a first direction to perforate media  22  into face  24  and in a second direction to perforate media  22  into face  26 . 
     Torque source  36  comprises a device configured to supply torque to perforator components  32  and  34 . In one embodiment, torque source  36  comprises a motor. Torque source  36  is operably coupled to perforator components  32  and  34  by transmission  68  which may comprise a series of gears, a belt and pulley arrangement, a chain and sprocket arrangement, a toothed pinion and toothed belt arrangement and the like. In one embodiment, transmission  68  is configured such that torque source  36  synchronously drives or rotates perforator components  32  and  34 . In other embodiments, torque source  36  and transmission  68  may be configured to independently rotate perforator components  32  and  34 . In one embodiment, torque source  36  may comprise independent motors or other sources of torque for independently driving components  32  and  34 . 
     As further shown by  FIG. 1 , torque source  36  is additionally operably coupled to media feed  30  by transmission  70  which may comprise a series of gears, a belt and pulley arrangement, a chain and sprocket arrangement, a toothed pinion and toothed belt and the like. Torque source  36  supplies torque to drive media feed  30 . In other embodiments, system  20  may utilize sources of torque other than torque source  36  for driving media feed  30 . 
     Controller  42  comprises a processing unit configured to generate control signals directing the operation of media feed  30  and torque source  36 . For purposes of this disclosure, the term “processing unit” shall mean a conventionally known or future developed processor that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processor to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. Controller  42  is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit. 
       FIGS. 1-3  schematically illustrate example operation states for perforator system  20 .  FIG. 1  illustrates torque source  36  rotatably driving perforator components  32  and  34  to the open position shown. Once in this open position, perforator components  32  and  34  are generally stationary and do not rotate. In other embodiments, components  32  and  34  may be rotating, but at a slower surface velocity as compared to movement of media  22  by media feed  30 . As a result, anvils  50 ,  60 , and blades  52 ,  62  may be positioned at one of a continuum of potential locations relative to media  22 . In other words, components  32  and  34  may be positioned on opposite sides of media  22  at any one of a number of locations along media  22 . For example, a multitude of different lengths of media  22 , including lengths greater than the circumferential spacing between consecutive anvils  50 ,  60 , and blades  60 ,  62 , may be moved past components  32  and  34 . This enables perforations to be formed at multiple locations and variable spacings. For example, perforations may be formed at 0.25 inches from the edge of media  22 , at 0.5 inches from the edge of media  22 , at 3 inches from the edge of media  22 , at 3.25 inches from the edge of media  22  and so on. 
       FIG. 1  further illustrates media feed  30  moving media  22  between perforator components  32  and  34  relative to perforator components  32  and  34  along media path  44  in either of the directions indicated by the arrows  72 . As a result, media feed  30  may position media  22  at any one of a multitude relative positions with respect to components  32  and  34  for forming perforations in media  22  at multiple locations with selected spacings between such multiple perforations. 
     Although  FIG. 1  illustrates media  22  as passing between, relative to and potentially in contact with stationary or slower moving opposing portions of rotatable members  48  and  58  between blades  50 B,  60 B and anvils  52 B,  62 B, media  22  may also be moved between and relative to other opposing stationary or slower moving portions of rotatable members  48  and  58  located between other anvils and other blades. For example, perforator components  32  and  34  may alternatively be positioned such that media  22  is moved past and between stationary or slower moving opposing portions of rotatable members  48  and  58  extending between anvils  52 A and  52 B and between blades  60 A and  60 B. The particular angular positioning of perforator components  32  and  34  may be varied depending upon a desired perforate pattern to be formed in media  22 . In some embodiments, the blades and anvils described herein may be replaced with the blades and anvils described in U.S. patent application Ser. No. 11/101,329, entitled “Creaser” and filed Apr. 7, 2005, which is hereby incorporated by reference. 
       FIG. 2  schematically illustrates perforator system  20  in a first perforating state in which media  22  is perforated from side or face  26 . In particular, once media  22  has been properly positioned with respect to perforator components  32  and  34  while components  32  and  34  are in the open state shown in  FIG. 1 , torque source  36 , in response to control signals from controller  42 , rotates components  32  and  34  in the direction indicated by arrows  74  to move blade  60   b  into engagement with face  26  of media  22  opposite to and against anvil  52 B. In the particular example shown, one or more tips of blade  60 B pierces media  22  against anvil  52 B to form perforation  76  in media  22 . In one embodiment, perforation  76  may be formed entirely across media  22 . In another embodiment, perforation  76  may be intermittently located and spaced along media  22 . Perforation  76  facilitates subsequent tearing of media  22  along perforation  76 . Perforation  76  facilitates the creation of a straight and properly located tear by a person manually tearing media  22  along perforation  76 . 
       FIG. 3  schematically illustrates perforator system  20  in a second perforating state after media  22  has been appropriately positioned with respect to perforator components  32  and  34  as shown in  FIG. 1 . As shown in  FIG. 3 , torque source  36  has rotated perforator components  32  and  34  in the direction indicated by arrows  78  from the position shown in  FIG. 1  to the position shown in  FIG. 3  in which blade  50 B engages and pierces side or face  24  of media  22  against an opposite anvil  62 B to form perforation  80  extending into face  24  of media  22 . 
     In the particular example shown, the blades  50  are consecutively coupled to rotatable member  48  and anvils  52  are consecutively coupled to rotatable member  48 . Likewise, blades  60  are consecutively coupled to rotatable member  58  and anvils  62  are consecutively coupled to rotatable member  58 . In other words, blades  50  are coupled to rotatable member  48  without intervening or intermediate anvils. Blades  60  are coupled to a rotatable member  58  without intervening or intermediate anvils. Anvils  52  are coupled to rotatable member  48  without intermediate or intervening blades. Likewise, anvils  62  are coupled to rotatable member  58  without intermediate or intervening blades. Blades  60  are configured to interact with anvils  52  while blades  50  are configured to interact with anvils  62 . This arrangement of blades  50 , blades  60 , anvils  52  and anvils  62  enables system  20  to selectively form consecutive perforations  76  along media  22 , consecutive perforations  80  along media  22  or to consecutively form perforations  76  and  80  in any order. Because system  20  may consecutively form perforations  76 , may consecutively form perforations  80  or may consecutively form perforations  76  and  80  in any order and because system  20  is configured to move media  22  between and relative to perforator components  32  and  34  to consecutively control the spacing or distance between perforations  76  and/or  80 , system  20  may form a variety of perforate patterns in media  22  to facilitate a variety of tearing patterns. 
       FIG. 4  illustrates three example tear patterns that may be formed by tearing media  22  along patterns of perforations  76  and  80  formed by system  20 . In particular,  FIG. 4  illustrates first pattern  100 , second pattern  102 , and third pattern  104 . The first pattern  100  comprises a series of six substantially linear sets of perforations  106  formed in media  22 . The sets of perforations  106  are shown as being evenly spaced, but may have different spacings between adjacent sets of perforations  106 . The second pattern  102  includes two sets of perforations  108  located in non-symmetrical fashion on the media  22 . The third pattern  104  shows sets of perforations  110 . 
       FIG. 5  schematically illustrates perforator system  120 , another embodiment of perforator system  20 , incorporated as part of an imaging system  117 . In addition to perforator system  120 , imaging system  117  includes housing  123 , media input  125 , media output  127  and imaging component  129 . Perforator system  120  is similar to perforator system  20  except that perforator system  120  includes media feed  130 , torque source  136  and controller  142  in lieu of media feed  30 , torque source  36  and controller  42 , respectively. Media feed  130  is similar to media feed  30  except that media feed  130  is configured to move media  22  along a media path  144  from media input  125 , relative to imaging component  129  and to media output  127 . In the particular example shown, media feed  130  is configured to pick an individual sheet of media  22  from a stack of sheets of media  22  provided at media input  125 . Media feed  130  is further configured to position the picked sheet  22  relative to imaging component  129  and to move the sheet of media  22  relative to perforator components  32  and  34  during perforating. After perforating, media feed  130  is configured to move the perforated sheet of media  22  to media output  127 . As shown in  FIG. 5 , when perforator components  32  and  34  are in an open state, media feed  130  may move a sheet of media  22  relative to perforator components  32  and  34  while perforator components  32  and  34  remain stationary and without additional perforating of the sheet of media  22  being moved between perforator components  32  and  34 . As discussed above, this facilitates selective positioning of the sheet of media  22  relative to perforator components  32  and  34  for forming perforations in the sheet of media  22  at selected spacings. Media feed  130  may comprise a drum, a series of rollers, a series of belts, shuttle trays, and combinations thereof as well as other mechanisms configured to move and transport media  22 . 
     Torque source  136  is similar to torque source  36  except that torque source  136  is configured to supply torque to media feed  130  in lieu of media feed  30 . Torque source  136  may comprise one or more individual sources of torque, such as motors, which are operably coupled to media feed  130  by transmission  70  (described above). In one embodiment, torque source  136  may comprise a first motor configured to supply torque to media feed  130  and a second distinct motor, such as a stepper motor, configured to supply torque to perforator components  32  and  34 . 
     Controller  142  is similar to controller  42  except that controller  142  is configured to generate additional control signals directing the operation of imaging component  129 . In particular, controller  142  comprises one or more processing units configured to generate control signals directing the operation of torque source  136  which drives media feed  130  and perforator components  32 ,  34 . Controller  142  further generates control signals based upon input image data directing the operation of imaging component  129 . 
     With the incorporation of perforator system  120 , imaging system  117  is configured to form an image upon media  22  while also perforating media  22  for subsequent tearing. Housing  123  of imaging system  117  generally comprises a structure configured to support and enclose each of the components of imaging system  117 . As a result, imaging system  117  is a generally self-contained unit. The exact configuration of housing  123  may vary depending upon such factors as the other components of imaging system  117 . 
     Media input  125  comprises that portion of imaging system  117  configured to facilitate input of media  22 . In the particular embodiment illustrated, media input  125  is configured to facilitate input of a stack of sheets of media  22 . In one embodiment, media input  125  may include a tray aligning the sheets of media  22 . In other embodiments, media input  125  may comprise other structures. 
     Media output  127  comprises that portion of imaging system  117  at which sheets of media  22  are discharged. In one embodiment, media output  127  may comprise an opening in housing  123  through which sheets are discharged. In another embodiment, media output  127  may comprise a storage bin or other structure configured to store sheets of media  22  upon which images have been formed and/or have been perforated by perforator system  120 . 
     Imaging component  129  comprises a component configured to form an image upon media  22 . In one embodiment, imaging component  129  comprises a fluid dispensing device configured to dispense imaging fluid such as fixing agents and inks upon media  22 . In one exemplar embodiment, imaging component  129  comprises an inkjet print head. In another embodiment, imaging component  129  comprises a device configured to deposit toner upon media  22 . For example, in one embodiment, imaging component  129  might comprise photo sensitive surface configured to be electrostaticly charged so as to form an electrostatic image and to electrostaticly transfer toner to media  22 . In still other embodiments, imaging component  129  may comprise other devices configured to interact with media  22  so as to form an image upon media  22 . 
     In operation, controller  142  generates control signals which are transmitted to torque source  136  which drives media feed  130  to pick a sheet of media  22  and to transfer the sheet of media  22  to a position relative to imaging component  129 . Controller  142  generates additional control signals directing imaging component  129  to form an image upon media  22  based upon input image data. Thereafter, controller  142  generates control signals directing torque source  136  to drive media feed  130  to move media  22  relative to perforator components  32  and  34 . Controller  142  also generates control signals directing torque source  136  to drive perforator components  32  and  34  via transmission  68  to selectively form perforations  76  and  80  (shown in  FIGS. 2 and 3 ) at appropriate spacings to facilitate the desired tear pattern such as those shown in  FIG. 4  or other tear patterns. 
     As shown in phantom in  FIG. 5 , in other embodiments, perforator system  120  may additionally include perforator components  132  and  134  configured to be selectively driven by torque source  136  via transmission  168 . Perforator components  132  and  134  are similar to perforator components  32  and  34 , respectively in that perforator components  132  and  134  are located on opposite sides of media path  144  and are configured to selectively form perforations  76  and  80  or to allow media  22  to move between and relative to components  132  and  134 . Perforator components  132  and  134  may enhance the versatility of perforator system  120  by enabling perforator system  120  to form a greater number of different combinations of consecutive perforations in media  22 . For example, perforator components  32 ,  34 ,  132  and  134  may be selectively driven to form greater than two consecutive perforations  76  (shown in  FIG. 2 ) or greater than two consecutive perforations  80  (shown in  FIG. 3 ) in media  22 . Although perforator components  132  and  134  illustrated as being substantially identical to perforator components  32  and  34 , respectively, perforator components  132  and  134  may alternatively have different configurations. In particular embodiments, each of perforator components  32 ,  34 ,  132  and  134  may have other configurations including other arrangements of blades and anvils. 
       FIG. 6  schematically illustrates perforator system  220 , another embodiment of perforator system  120 , configured as an add-on module for use with imaging system  217 . Perforator system  220  is similar to perforator system  20  except that perforator system  220  additionally includes housing  284 , connectors  286 , input opening  288 , output opening  290  and communications interface  292 . The remaining components of perforator system  220  which correspond to similar components of perforator system  20  are numbered similarly. Housing  284  comprises a structure configured to enclose, support and substantially surround components of perforator system  220 . Connectors  286  comprise structures coupled to housing  284  and configured to releasably secure or attach housing  284  and perforator system  220  to imaging system  217 . In one embodiment, connectors  286  may comprise resiliently flexible hooks configured to snap into corresponding detents of imaging system  217 . In other embodiments, this relationship may be reversed or connector  286  may comprise other mechanisms for releasably fastening housing  284  and perforator system  220  to imaging system  217 . 
     Input opening  288  comprises an opening within housing  284  configured to receive media  22  from imaging system  217 . Output opening  290  comprises an opening in housing  284  configured to permit removal or discharge of perforated or unperforated media  22  from perforator system  220 . In one embodiment, output opening  290  may comprise an opening configured to receive a tray or storage bin. In other embodiments, output opening  290  may comprise an opening through which media  22  is discharged by media feed  30 . 
     Communications interface  292  comprises a port within housing  284  configured to facilitate communication with controller  242  of imaging system  217 . In one embodiment, interface  292  may comprise a connector for connecting an optical or electrical communication cable or wire to perforator system  220 . In another embodiment, interface  292  may comprise a plug configured to releasably mate with a corresponding plug associated with imaging system  217 . In other embodiments in which communication is performed wirelessly, communications interface  292  may comprise a transceiver configured to receive such signals from imaging system  217 . 
     Imaging system  217  is similar to imaging system  117  except that imaging system  217  omits those components of perforator system  120 . Imaging  217  includes housing  223 , connectors  225 , media input  125 , media output  227 , imaging component  129 , media feed  230 , actuator  236  and controller  242 . Housing  223  comprises one or more structures configured to enclose and support those components of imaging system  217 . Connectors  225  comprise structures coupled to housing  223  configured to cooperate with connectors  286  of perforator system  220  releasably mount or attach perforator system  220  to housing  223  and imaging system  217 . In one embodiment in which connectors  286  of perforator system  220  comprise openings or detents, connectors  225  may comprise resilient hooks or prongs configured to be received within such openings of connectors  286 . In other embodiments, connector  225  may comprise other mechanisms configured to releasably connect imaging system  217  and perforator system  220 . 
     Media input  125  is described above with respect to imaging system  117  and generally comprises a structure configured to input media  22  to imaging system  217 . Media output  227  comprises an opening within housing  223  configured to facilitate passage of media  22  from imaging system  217  to perforator system  220 . Although media output  227  is illustrated as an opening in housing  223 , output  227  alternatively may comprise an opening formed by removing or moving a door, panel or other structure of housing  223 . 
     Imaging component  129  is described above with respect to imaging system  117  and is configured to form an image upon media  22 . Media feed  230  is similar to media feed  130  except that media feed  230  is configured to move and transport media  22  from media input  125 , relative to imaging component  129  and to media output  227 . Media feed  230  is further configured to move media  22  through media input  288  of perforator system  220  until the media is engaged by media feed  30  of perforator system  220 . Media feed  230  may comprise a drum, a series of rollers, a series of belts, a shuttle tray and combinations thereof. 
     Actuator  236  comprises a source of power for media feed  230 . In one embodiment, actuator  236  may comprise a torque source for providing torque to media feed  230 . In another embodiment, actuator  236  may comprise a source of linear motion such as cylinder-piston assembly, solenoid and the like configured to drive media feed  230 . As shown by  FIG. 6 , actuator  236  is operably coupled to media feed  230  by transmission  70  which may comprise one or more gears, belt and pulley arrangements, chain and sprocket arrangements, toothed belt and pinion arrangements and the like. 
     Controller  242  comprises a processing unit configured to generate control signals directing the operation of actuator  236  of imaging system  217 . Controller  242  is further configured to generate control signals directing the operation of torque source  36  of perforator system  220 . Control signals generated by controller  242  are communicated to torque source  36  of perforator system  220  by communications interface  294 . 
     Communications interface  294  comprises a device configured to facilitate transfer of control signals from controller  242  of imaging system  217  to perforator system  220 . In one embodiment, communication interface  294  may comprise a connector configured to be connected to an optical or electrical wire or cable which is itself connected to perforator system  220 . In another embodiment, interface  294  may comprise a plug configured to mate with interface  292  of perforator system  220  for the transmission of control signals. In still another embodiment, interface  294  may comprise a transceiver for communicating and/or receiving wireless signals between imagining system  217  and perforator system  220 . 
     In operation, controller  242  generates control signals based upon received or input image data. Such control signals are transmitted to actuator  236  and imaging component  129  to form an image upon media  22 . Once an image has been formed upon the media, controller  242  generates additional control signals directing actuator  236  to drive media feed  230  to move the image containing sheet of media  22  along media path  243  and out media output  227  and into engagement with media feed  30  of perforator system  220 . Based upon perforate data designating a pattern of perforations to be formed by perforator system  220 , controller  242  communicates control signals to torque source  36  via communication interfaces  294  and  292 . Such control signals from controller  242  direct torque source  36  to appropriately position perforator components  32  and  34  with respect to media  22  in either the open state (shown in  FIG. 1 ) or the two perforating states (shown in  FIGS. 2 and 3 ) for forming perforations  76  or perforations  80 . Once each of the desired perforations have been formed in media  22 , controller  242  generates control signals directing torque source  36  to drive media feed  30  so as to move the perforated media  22  through output opening  290  along media path  244 . 
       FIG. 7  schematically illustrates perforator system  320 , another embodiment of perforator system  20 , configured as an add-on module for use with imaging system  317 . Perforator system  320  is similar to perforator system  20  except that perforator system  320  specifically includes media feed  330  in lieu of media feed  30 , and additionally includes housing  384 , media input  388 , media output  390 , sensor  391 , communications interface  392  and torque interface  393 . Those remaining components of perforator system  320  which correspond to components of perforator system  20  are numbered similarly. 
     Media feed  330  is configured to transport or move media  22  along media feed path  344  from media input  388  to media output  390 . In particular, media feed  330  is configured to move media  22  relative to perforator components  32  and  34  while perforator components  32  and  34  are substantially stationary. In the particular example illustrated, media feed  30  is configured to move media  22  in a generally linear plane between perforator components  32  and  34  substantially perpendicular to the axes about which perforator components  32  and  34  rotate. In other embodiments, media feed  330  may be configured to move media  22  between perforator components  32  and  34  in other fashions. In the particular example illustrated, media feed  330  comprises an upstream pair of rollers  400 ,  402  and a downstream pair of rollers  404 ,  406 . In other embodiments, media feed  330  may comprise other structures to engage and move media along media path  344 . 
     Housing  384  comprises one or more structures configured to enclose and support media feed  330 , perforator components  32 ,  34 , torque source  36 , communications interface  392  and torque interface  393 . In one embodiment, housing  384  is configured to be releasably attached to imaging system  317 . The exact configuration of housing  384  may vary depending upon the configuration of the components it houses as well as its mounting relationship to imaging system  317 . 
     Media input  388  comprises an opening in housing  384  configured to be aligned with an output opening on imaging system  317  such that media  22  may be moved into media path  344  within housing  384  and into engagement with media feed  330 . Media output  390  comprises an opening in housing  384  configured for the discharge of perforated media  22 . In the particular example shown, media output  390  additionally includes a tray in which discharge media may be stored. 
     Sensor  391  comprises a sensing device configured to sense positioning of media along media path  344 . In one embodiment, sensor  391  may be configured to sense a leading or a trailing edge of media. In another embodiment, sensor  391  may be configured to sense other portions of media. Controller  242  drives torque source  36  based upon signals received from sensor  391 . Although sensor  391  is depicted as being located between perforator component  32  and roller  400 , sensor  391  may alternatively be located at other positions. For example, sensor  391  may alternatively be located between perforator component  32  and roller  404 , between roller  400  and perforator component  34 , between perforator component  34  and roller  406  or at other locations. 
     Communications interface  392  is similar to communications interface  292  of perforator system  220  (shown in  FIG. 6 ). Communications interface  392  is configured to facilitate communication between controller  242  of imaging system  317  and torque source  36  of perforator system  320 . In one embodiment, interface  392  may comprise a connector for connecting an optical or electrical communication cable or wire to perforator system  320 . In another embodiment, interface  392  may comprise a plug configured to releasably mate with a corresponding plug associated with imaging system  317 . In other embodiments in which communication is performed wirelessly, communications interface  392  may comprise a receiver configured to receive such signals from imaging system  317 . 
     Torque interface  393  comprises a mechanism configured to facilitate the transfer of power or torque from imaging system  317  to media feed  330  when perforator system  320  is mounted or otherwise connected to imaging system  317 . In the particular embodiment illustrated, torque interface  393  facilitates the transfer of torque to each of rollers  400 ,  404  which are rotatably driven opposite to idler rollers  402  and  406 , respectively. In one embodiment, torque interface  393  may comprise a gear configured to mesh with an opposite corresponding gear of imaging system  317 . In other embodiments, other means for transmitting torque from imaging system  317  to perforator system  320  may be utilized. 
     Imaging system  317  comprises a system configured to form an image upon media  22 . Imaging system  317  is further configured to be removably attached or mounted to perforator system  320 , to move media into perforator system  320 , to supply torque to media feed  330  and to control operation of torque source  36  of perforator system  320  to selectively perforate media. Imaging system  317  is similar to imaging system  217  (shown and described with respect to  FIG. 6 ) except that imaging system  317  additionally includes torque interface  395 . The remaining components of imaging system  317  which correspond to imaging system  217  are numbered similarly. Torque interface  395  comprises a mechanism configured to interact with torque interface  393  of perforator system  320  so as to transfer torque from actuator  236  to rollers  400  and  404  of media feed  330 . In one particular embodiment, torque interface  395  comprises a gear configured to mesh with a gear of torque interface  393  when perforator system  320  is releasably mounted to housing  223  of imaging system  317 . In other embodiments other means for transferring torque or other force from actuator  236  to media feed  330  may be utilized. 
     In operation, controller  242  generates control signals directing actuator  236  to drive media feed  230  so as to pick a sheet of media  22  and to transfer the sheet of media  22  along media path  243  relative to imaging component  129 . Controller  242  further generates control signals based upon image data directing imaging component  129  to form an image upon the picked sheet of media  22 . Thereafter, controller  242  generates control signals directing actuator  236  to drive media feed  230  to further move the sheet of media  22  along media feed path  243  out media output  227  and into media input  388  of perforator system  320  until the sheet of media  22  is engaged by rollers  400  and  402  of media feed  330 . Controller  242  generates control signals directing actuator  236  to supply torque to rollers  400  and  404  via a transmission  370 , torque interface  395 , torque interface  393  and transmission  397 . Controller  242  generates control signals which are transmitted to torque source  36  of perforator system  320  via communication interfaces  292  and  392  directing torque source  36  to selectively rotate perforator components  32  and  34  to appropriately position perforator components  32  and  34  in either the open state (shown) or either of the two perforating states (shown in  FIGS. 2 and 3 ) to perforate the sheet of media  22 . Once all of the desired perforations have been formed in the sheet of media  22 , controller  242  generates control signals directing actuator  236  to further supply torque to media feed  330  so as to discharge sheet of media  22  to media output  390 . 
       FIGS. 8-12  illustrate perforator system  420 , a specific embodiment of perforator system  320  shown and described with respect to  FIG. 7 . Perforator system  420  generally includes housing  484 , media guides  486  (shown in  FIGS. 11 and 12 ) media input  488 , media output  490 , communications interface  492 , torque interface  493 , transmission  497 , media feed  530 , perforator components  532 ,  534 , torque source  536  and sensors  591  and  595 . Housing  484  comprises one or more structures configured to enclose and support the remaining components of perforator system  420 . In the particular embodiment illustrated, housing  484  is configured to be releasably mounted to an underlying printer such as imaging system  317  shown and described with respect to  FIG. 7 . In other embodiments, housing  484  may have other configurations and may be mounted to a printer in other fashions. 
     Media guides  486  (shown in  FIGS. 11 and 12 ) comprise structures supported by housing  484  and configured to guide media from an underlying printer to media feed  530 . 
     Media input  488  (shown in  FIG. 11 ) comprises an opening or gap along the interior of housing  484  through which media from the underlying printer is supplied between the media guides  486 . Media output  490  comprises a discharge area for media perforated by perforator system  420 . As shown in  FIG. 8 , media output  490  may comprise an elongate tray upon which perforated media may be stored. In other embodiments, media output may have other configurations or may alternatively comprise an opening in housing  484 . 
     Communication interface  492  (schematically shown in  FIG. 9 ) is similar to communication interface  292  shown and described with respect to  FIG. 7 . Communication interface  492  is configured to facilitate communication between a controller, such as controller  242  (shown in  FIG. 7 ), of a printer and sensors  591  and  595 . Interface  492  further facilitates communication between the controller of the printer and torque source  536 . In other embodiments, interface  492  may be omitted where perforator system  420  includes its own controller (such as controller  42  shown and described with respect to  FIG. 1 ) and a user input configured to enable a person to select a desired perforating pattern. 
     Torque interface  493  comprises a structure configured to transmit or facilitate the transfer of torque from a printer, such as imaging system  317  shown and described with respect to  FIG. 7 , to media feed  530 . In the particular embodiment illustrated, torque interface  493  comprises a gear configured to mesh with an adjacent gear (not shown) of a printer. In other embodiments, torque interface  493  may comprise other mechanisms configured to transfer torque to perforator system  420  from an associated printer or imaging system. In still other embodiments, torque interface  493  may be omitted where perforator system  420  includes a torque source for driving media feed  530 . 
     Transmission  497  comprises a mechanism configured to transmit torque received via torque interface  493  to media feed  530 . In the particular embodiment illustrated, transmission  497  includes pulleys  538 ,  539 ,  541 ,  543 ,  545  and belts or o-rings  547 ,  549 ,  551  and  553 . Pulley  538  is operably coupled to torque interface  493 , is operably coupled to an input portion of media feed  530 , and is operably connected to pulley  539  by o-ring  547 . Pulley  539  is rotatably supported by structure  487  and is operably coupled to pulley  541  by o-ring  549 . Pulley  541  is rotatably supported by structure  487  and is operably coupled to pulley  543  by o-ring  551 . Pulley  543  is rotatably supported by structure  487  and is operably coupled to pulley  545  by o-ring  553 . Pulley  545  is connected to an output portion of media feed  530 . Torque received via torque interface  493  rotatably drives the input portion of media feed  530 . At the same time, torque is transmitted over perforator components  532  and  534  to rotatably drive an output portion of media feed  530 . Although transmission  497  is illustrated as extending over perforator components  532  and  534  for space savings, transmission  497  may alternatively extend beneath or along an axial end of perforator components  532 ,  534 . Although transmission  497  is illustrated as including pulleys and o-rings, transmission  497  may alternatively include a series of gears, one or more chain and sprocket arrangements, one or more toothed pinion and toothed belt arrangements and the like. 
     Media feed  530  comprises a mechanism configured to move media, such as sheets of media, between perforator components  532  and  534  while perforator components  532  and  534  remain substantially stationary and in an open state as shown in  FIGS. 9 and 10 . Media feed  530  generally includes an input portion including shaft  557 , nip rollers  559 , idler rollers  561  (shown in  FIG. 9 ), shaft  563 , nip rollers  565  (shown in  FIG. 10 ) and idler rollers  567 . Shaft  557  is rotatably supported by media guide  486  and is coupled to torque interface  493  so as to be rotatably driven in response to rotation of torque interface  493 . Shaft  557  is coupled to pulley  538  such that pulley  538  is rotated upon rotation of shaft  557  to transmit torque to shaft  563  of the output portion of media feed  530 . Shaft  557  supports nip rollers  559 . 
     Nip rollers  559  are configured to be rotatably driven with the rotation of shaft  557 . Nip rollers  559  oppose idler rollers  561 . Nip rollers  559  and idler rollers  561  cooperate to engage opposite sides of a media on an input side of perforator components  532  and  534  to drive media with respect to perforator components  532 ,  534 . 
     Shaft  563  is a shaft rotatably supported by a bearing block  537  associated with media guide  486 . Shaft  563  is coupled to pulley  545 . Shaft  563  extends along an output side of perforator components  532  and  534  and is coupled to pulley  545  so as to rotate with rotation of pulley  545 . Shaft  563  is further coupled to nip rollers  565  such that nip rollers  565  rotate upon the rotation of shaft  563 . Nip rollers  565  comprise cylindrical members opposing idler rollers  567 . Nip rollers  565  and idler rollers  567  cooperate to engage opposite sides of a media to move media with respect to perforator components  532  and  534 . 
     Perforator components  532  and  534  are similar to perforator components  32  and  34  (described with respect to  FIG. 1 ). Perforator component  532  includes rotatable member  648 , blades  650 A,  650 B (collectively referred to as blades  650 ), anvils  652 A,  652 B (collectively referred to as anvils  652 ), drive gear  655  and drive shaft  656 . Perforator component  534  includes rotatable member  658 , blades  660 A,  660 B (collectively referred to as blades  660 ), anvils  662 A,  662 B (collectively referred to as anvils  662 ) and drive gear  665 . Rotatable members  648  and  658  are substantially similar to one another. Each of rotatable member  648  and  658  comprises an elongate cylindrical structure coupled to their respective blades and anvils. In particular, rotatable member  648  supports blades  650  and anvils  652  for rotation about axis  654 . Rotatable member  658  supports blades  660  and anvils  662  for rotation about axis  664 . 
     The blades  650  include discrete knives  651 , which may also be referred to as blades or pins. The discrete knives  651  are arranged in substantially linear fashion along a longitudinal direction of the surface of the rotatable member  648 . The anvils  652  include apertures  653  that are also arranged such that the knives  651  may at least partially enter the apertures  653  as the knives  651  and apertures  653  move into opposing positions to pierce media. 
     As shown by  FIG. 11 , rotatable members  648  and  658  each include elongate slots or grooves  670  in which blades  650  and blades  660  are received and secured. Rotatable members  648  and  658  additionally include channels  672  in which anvils  652  and  662  are received and secured. Channels  672  each include an elongate groove or cavity  674 . As shown by  FIG. 12A , anvil  662  includes holes  677  configured to receive at least a portion of the blade  650  when the blade  650  is piercing or deforming the media  22 . 
     As further shown by  FIG. 11 , each of blades  650 ,  660  has elongate tapering sides  676  terminating at a point  779 . Each of anvils  652 ,  662  includes an elastomeric blade-engaging portion. This portion may comprise a series of apertures, a longitudinally-elongated groove or notch (not shown). 
     According to one exemplary embodiment, blades  650 ,  660  are formed from a relatively rigid material such as steel. Anvils  652 ,  662  are formed from a resiliently compressible material having a shore A durometer of between about  40  and  60 . In one embodiment, anvils  652 ,  662  include blade engaging portions formed from a material such as polyurethane. In other embodiments. Anvils  652 ,  662  may be formed from other materials such as neoprene or Buna-N rubber. Although the entirety of each of anvils  652 ,  662  is illustrated as being formed from a single material or a blend of materials, in other embodiments, anvil  652 ,  662  may be formed from multiple portions of materials co-molded or otherwise secured to one another. 
     In the particular embodiment illustrated in  FIGS. 8-12 , blades  650 ,  660  and anvils  652 ,  662  are generally arranged similar to blades  50 ,  60  and anvils  52 ,  62  of perforator system  20  (shown and described with respect to  FIGS. 1-3 ). As a result, perforator components  632 ,  634  are configured to form each of the perforating patterns for the associated tear patterns illustrated in  FIG. 4 . In other embodiments, perforator components  632  and  634  may have a greater or smaller number of such anvils and blades in alternative arrangements about rotatable member  648  and  658 . 
     In the particular embodiment illustrated, axes  654  and  664  about which rotatable members  648  and  658  rotate are spaced from one another by about 25.4 millimeters (one inch). The outer surface of rotatable members  648  and  658  are spaced from one another by at least about 3.4 millimeters. As a result, when in an open position, perforator components  632  and  634  may accommodate movement of media between components  632  and  634  by media feed  530  of up to a thickness of about 3.4 millimeters while components  632  and  634  are stationary (not rotating). In other embodiments, components  632  and  634  may be spaced from one another by other distances. 
     Drive gears  655  and  665  are coupled to rotatable members  648  and  658 , respectively. Drive gears  655  and  665  mesh with one another so as to synchronize rotation of components  532  and  534 . In other embodiments, rotation of components  532  and  534  may be synchronized by other mechanisms such as chain and sprocket arrangements, belt and pulley arrangements or other similar mechanical arrangements. In other embodiments, components  532  and  534  may be rotatably driven by separate torque sources at the same speed. 
     Drive shaft  656  is coupled to rotatable member  648  and is in operable engagement with torque source  536 . Torque source  536  comprises a mechanism to supply torque to perforator component  532  which results in perforator component  534  also being rotated. In the particular embodiment illustrated, torque source  536  comprises a motor operably coupled to drive shaft  656 , which comprises a follower gear, by worm gear  692  connected to an output shaft of motor  690 . In one particular embodiment, torque source  536  comprises a stepper motor configured to selectively drive perforator components  532  and  534  in either of opposite directions. In other embodiments, drive shaft  656  may have other configurations and torque source  536  may be operably coupled to shaft  656  by other mechanisms such as a belt and pulley arrangement, a chain and sprocket arrangement, a series of gears, or the like. 
     Sensor  591  comprises a sensing device configured to detect the presence of media. In the particular embodiment illustrated, sensor  591  comprises a reflective sensor supported by media guide  486  (shown in  FIGS. 11 and 12 ). In other embodiments, sensor  591  may comprise other sensing devices. In the particular example shown, sensor  591  is supported on an input side of perforator components  532 ,  534 . In another embodiment, sensor  591  may be located and supported on an output side of perforator components  532 ,  534 . Sensor  591  detects a leading edge of media being fed by media feed  530  to perforator components  532 ,  534 . Sensor  591  generates signals based upon detection of media and transmits such signals to the controller of the associated printer via interface  492 . 
     Sensor  595  comprises a sensing device configured to sense position of perforator component  532  from which may be determined the positioning of perforator component  534 . In embodiments where perforator components  532  and  534  are not synchronized with one another, system  420  may include an additional sensor for detecting the position of perforator component  534 . In the particular example shown, sensor  595  comprises an interference sensor comprising an encoder wheel  694  having slots  696  and homing slot  697 , and optical sensor  698 . Slots  696  permit light from a transmitter portion of sensor  698  to be received by a light sensitive portion of sensor  698  as perforator component  532  is rotatably driven by torque source  536 . Homing slot  697  facilitates counting of the number of rotations of wheel  694  by optical sensor  698 . In response to rotation of wheel  694 , optical sensor  698  generates and transmits signals to the controller of the associated printer (not shown) via interface  492 . In other embodiments, sensor  595  may comprise other sensing devices. 
     In operation, a controller of an associated printer, such as controller  242  of imaging system  317  (shown and described with respect to  FIG. 7 ) generates control signals causing an actuator or torque source associated with the printer to transmit torque to media feed  530  via torque interface  493 . The torque transmitted by torque interface  493  results in nip rollers  559  being rotatably driven. The torque is further transmitted by transmission  497  to rotatably drive nip rollers  565 . As a result, a sheet of media from the associated printer is fed to a position between perforator components  532  and  534 . Based upon signals received from sensor  591  as well as the last known positioning of perforator components  532  and  534  as indicated by signals from sensor  595  and/or an encoder associated with torque source  536 , the controller of the associated printer generates control signals which are transmitted to motor  690  via interface  492 . In response to such signals, torque source  536  rotatably drives perforator components  532  and  534  to either an open position shown in  FIG. 11 , allowing media feed  530  to selectively move a sheet of media relative to perforator components  532 ,  534  or a perforating state such as shown in  FIG. 12 . Once each of the desired perforations have been formed in the media  22  at the desired spacings, the controller of the associated printer generates control signals causing torque to be supplied to media feed  530  to further move the perforated sheet of media  22  to output  490  (shown in  FIG. 8 ). 
       FIGS. 13-15  illustrate perforator system  720 , another embodiment of perforator system  20  shown in  FIG. 1 . Perforator system  720  is similar to perforator system  20  except that perforator system  720  includes perforator components  732 ,  734  in lieu of perforator components  32  and  34 . Perforator component  732  includes rotatable member  748 , blades  750 A,  750 B (collectively referred to as blades  750 ) and anvils  752 A,  752 B (collectively referred to as anvils  752 ). Perforator component  734  includes rotatable member  758 , blades  760 A,  760 B (collectively referred to as blades  760 ) and anvils  762 A,  762 B (collectively referred to as anvils  762 ). Rotatable members  748  and  758  comprise elongate members configured to be rotatably driven about axes  754  and  764 , respectively. Rotatable members  748  and  758  are substantially identical to one another. Each of rotatable member  748  and  758  comprises an elongate polygonal structure configured to support blades  750 ,  760  and anvils  752 ,  762 . In the particular example shown, each of rotatable members  748  and  758  comprises an elongate structure having four substantially planar faces or sides  763 . 
     As shown by  FIG. 14 , the substantially planar sides  763  cooperate to form a generally planar media path  744  between perforator components  732  and  734  which facilitates movement of media  22  between perforator components  732  and  734  while components  732  and  734  remain substantially stationary. In the particular embodiment shown in  FIG. 14 , when components  732  and  734  are in the open position shown, opposing sides  763  of rotatable members  748  and  758  are substantially parallel to the opposing surfaces  765  of media guides  786  and the plane passing between rollers  759  and  761  of media feed  730 . This configuration may facilitate smoother movement of media  22  between and relative to perforator components  732  and  734  when components  732  and  734  are in the open state shown. 
     Although rotatable members  748  and  758  are illustrated as having four sides, perforator components  732  and  734  may alternatively have a greater or fewer number of such sides. Although rotatable members  748  and  758  are illustrated as being substantially identical to one another, in other embodiments rotatable members  748  and  758  may have different configurations as compared to one another. 
     As further shown by  FIG. 14 , each of rotatable members  748  and  758  includes elongate channels  767  and  769 . Channels  767  and  769  extend along axes  754  and  764  generally at an intersection of sides  763 . Channels  767  are configured to slideably receive and radially contain blades  750  and blades  760 . Likewise, channels  769  are configured to slideably receive and radially contain anvils  752  and anvils  762 . 
     In the particular example shown, each of rotatable members  748  and  758  include elongate hollow interior portions  771  between axes  754 ,  764  and faces or sides  763 . Hollow interior portions  771  may reduce the weight and power to rotatably drive perforator components  732  and  734  while reducing the material of rotatable members  748  and  758 . In the particular example shown, rotatable members  748  and  758  have extruded cross sections, reducing manufacturing costs of rotatable members  748  and  758 . In one embodiment, members  748  and  758  are extruded from lightweight metal such as aluminum. In other embodiments, rotatable member  748  and  758  may be formed from other materials and may have other configurations. 
     Blades  750  and blades  760  are substantially similar to one another. As shown by  FIG. 13 , blades  750  and blades  760  are configured to be slideably received and radially contained within channels  767 . In the particular example shown, channels  767  have a triangular cross-sectional shape having an elongate neck portion  773  extending along an opening  775 . Blades  750  and  760  have a generally triangular cross-sectional shape including a wide base portion  777  and an elongate tip  779 . When blades  750 ,  760  are slid along axes  754  and  764  into channels  767 , base  777  is captured while tip  779  projects through opening  775  beyond neck  773 . 
     In one particular embodiment, blades  750 ,  760  are formed from a relatively rigid material such as steel. In other embodiments, blades  750 ,  760  may be formed from other materials. Although blades  750 ,  760  are illustrated as being formed as single unitary bodies, blades  750 ,  760  may alternatively include multiple components or multiple materials molded, fastened, adhered or otherwise secured to one another. For example, in another embodiment, base  777  may be formed from a first material while that portion of blades  750 ,  760  providing tip  779  may be formed from another material or be provided by another member secured to base  777 . Although channels  767  and blades  750 ,  760  are illustrated as having generally triangular cross-sectional shapes, channels  767  and blades  750 ,  760  may have other configurations. 
     Anvils  752 ,  762  are substantially similar to one another. Each of anvils  752  and  762  is configured to be slideably received and radially contained within channel  769  of rotatable members  748  and  758 , respectively. In the particular example illustrated, each of anvils  752 ,  762  includes an axially extending base portion  781 , an elastomeric or resiliently compressible blade engaging portion  783  and an elongate cavity  785 . Base portion  781  is configured to be slideably positioned within channel  769  while radially retained in its associated anvil  752 ,  762  within channel  769 . In the particular example illustrated, channel  769  includes a narrowing neck portion  787  forming an opening  789 . Base portion  781  is radially captured within channel  769  below neck  787  with blade engaging portion  783  projecting through opening  789  beyond neck portion  787 . As shown by  FIG. 13 , anvils  752 ,  762  are axially slid into channel  769  along axes  754  and  764  to releasably couple anvil  752 ,  762  to rotatable members  748  and  758 . As a result, anvils  752 ,  762  may be removed for repair or replacement with reduced effort and potentially without, or with minimal use of, tools. 
     Blade engaging portions  783  of anvils  752 ,  762  comprise relatively soft, compressible surfaces against which tip  779  of blades  750 ,  760  depress media  22  during perforating as shown in  FIG. 15 . In one particular embodiment, anvils  752 ,  762  are formed as a single unitary body from a resiliently compressible material having a hardness of between about 40 and 60 shore A. In one embodiment, anvils  752 ,  762  are formed from a material such as polyurethane. In other embodiments, anvils  752  and  762  may be formed from other materials such as neoprene or Buna-N rubber. Although anvils  752  and  762  are illustrated as being integrally formed as single unitary bodies, anvils  752  and  762  may alternatively be formed from distinct components or members or molded, fastened, adhered or otherwise secured to one another. 
     Cavity  785  axially extends along a bottom side of anvils  752 ,  762  generally opposite to blade engaging portion  783 . In the particular example shown, cavity  785  comprise concave surfaces axially extending along anvils  752 ,  762 . Cavity  785  facilitates resilient deformation of blade engaging portions  783  when being engaged by blades  750 ,  760 . As shown by  FIG. 15 , tip  779  presses media  22  against portion  783  which results in anvil  752 A and its cavity  785  flattening out within channel  769  such that blade engaging portion  783  curves or partially wraps about tip  779  to form a sharp perforate in media  22 . In other embodiments, cavity  785  may be omitted and/or blade engaging portion  785  may include a notch for receiving tip  779 . 
       FIG. 16  illustrates an example embodiment of a portion of the system  720  and shows discrete tips  779  of blade  750 A within apertures  677  of anvil  762 A. The media  22  is shown as pierced by the tips  779  with the tips  779  engaged with the apertures  677 . 
       FIGS. 17 and 18  illustrate another example embodiment of a portion of the system  720 . In this embodiment, the blades  750 A and  760 A mesh with each other and pierce the media  22  during overlapping time frames. The blade  750 A may pierce the media  22  at a time when the blade  760 A is also piercing the media  22 . 
     As an example configuration, the tips  779  of the blade  750 A may be offset relative to the tips  779  of the blade  766 A by about one-half of the pitch distance P between the tips of the blade  750 A. Thus, in this embodiment, when the two rollers  732 ,  734  rotate, blades  750 A and  760 A mesh together to permit some of the perforations to come from the blade  750 A and the other of the perforations to come from the blade  760 A. In some embodiments, the blades  750 A and  760 A do not contact each other during perforating of the media  22 . 
     Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.