Abstract:
A maintenance system for maintaining a scalable printhead array comprises: a pair of tracks disposed in parallel and on opposite sides of a printhead array; a shaft extending between the tracks and configured to engage with each track to move along the tracks; a plurality of maintenance modules mounted in series along the shaft between the tracks and configured to move along the tracks with the shaft to perform maintenance operations on a plurality of printheads of the printhead array, the tracks being configured to guide the shaft and the plurality of maintenance modules along a path from a resting position to an operating position the printhead array and from which at least one of the plurality of maintenance modules performs a maintenance operation on at least one printhead of the printhead array; and an actuator configured to move the shaft along the tracks.

Description:
TECHNICAL FIELD 
     The system disclosed in this document relates to inkjet printers and, more particularly, to maintenance of scalable printhead arrays in such printers. 
     BACKGROUND 
     Inkjet printing is a process of producing an image on a substrate, such as a sheet of paper. Inkjet printing is an additive process in which one or more printheads eject drops of ink onto the substrate to form the image on the substrate. The printheads are operated with reference to digital image data that represents the image to be printed. Printing a multicolored image generally requires at least one printhead for each color. Additionally, printing high resolution images often requires multiple printheads of the same color that are interlaced to provide the increased resolution. Accordingly, many inkjet printing systems comprise arrays of several printheads arranged in rows and columns. 
       FIG. 20  shows a prior art architecture for a scalable printhead array  100 . The printhead array  100  includes a plurality of printhead assemblies  104 . The printhead array  100  is configured to include a variable number of printhead assemblies  104  arranged into rows and columns in a variety of possible arrangements. As shown, the printhead array  100  is scalable up to 50″ in width and includes fourteen printhead assemblies  104 . Each printhead assembly  104  is configured to receive a printhead  108  and to mount to frame  112  of the printhead array  100 .  FIG. 21  shows a more detailed view of one of the printhead assemblies  104  with a printhead  108 . 
     To ensure optimal performance of an inkjet printhead, the printheads must be well-maintained. Typically maintenance operations include purging, capping, and wiping. Prior art mechanisms for printhead maintenance are not easily adapted for scalable printhead arrays. Being able to configure a printhead maintenance system so it is easily scalable for use with a scalable printhead array would be beneficial. 
     SUMMARY 
     A printhead maintenance system that is scalable with a scalable printhead array includes a pair of tracks disposed in parallel and on opposite sides of the printhead array; a shaft extending between the pair of tracks and configured to engage with each track of the pair of tracks and to move along the pair of tracks; a plurality of maintenance modules mounted in series along the shaft between the pair of tracks and configured to move along the pair of tracks with the shaft to perform maintenance operations on a plurality of printheads of the printhead array, the pair of tracks being configured to guide the shaft and the plurality of maintenance modules along a path from a resting position to an operating position the printhead array and from which at least one of the plurality of maintenance modules performs a maintenance operation on at least one printhead of the printhead array; and an actuator configured to move the shaft along the pair of tracks. 
     A maintenance cart for a printhead array includes a body configured to move selectively along a path to the printhead array; a pair of tracks being mounted in parallel on the body and configured to position the pair of tracks on opposite sides of the printhead array in response to the body moving to the printhead array; a shaft extending between the pair of tracks and configured to engage with each track of the pair of tracks and to move along the pair of tracks; a plurality of maintenance modules mounted in series along the shaft between the pair of tracks, the plurality of maintenance modules being configured to move along the pair of tracks with the shaft to perform maintenance operations on a plurality of printheads of the printhead array in response to the body being positioned at the printhead array, the pair of tracks being configured to guide the shaft and the plurality of maintenance modules along a path from a resting position to an operating position from which at least one of the plurality of maintenance modules performs a maintenance operation on at least one printhead of the printhead array; and an actuator configured to move the shaft along the pair of tracks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and other features of the maintenance system and maintenance cart for a printhead array are explained in the following description, taken in connection with the accompanying drawings. 
         FIG. 1  shows a perspective view of a system for maintaining a scalable printhead array. 
         FIG. 2  shows a side view of the system of  FIG. 1  having maintenance modules in resting positions. 
         FIG. 3  shows a side view of the system of  FIG. 1  having wiper modules in operating positions. 
         FIG. 4  shows a side view of the system of  FIG. 1  having capping modules in operating positions. 
         FIG. 5  shows shifting wiper modules with a bias block and bias bracket. 
         FIG. 6  shows one embodiment of a bias block. 
         FIG. 7  shows a perspective view of a maintenance cart having a maintenance system for maintaining a scalable printhead array. 
         FIG. 8  shows a front view of the maintenance cart of  FIG. 7 . 
         FIG. 9  shows a side view of the maintenance cart of  FIG. 7  having maintenance modules in resting positions. 
         FIG. 10  shows a perspective view of a different embodiment of a maintenance cart for maintaining a scalable printhead array. 
         FIG. 11  shows a perspective view of one embodiment of a wiper module. 
         FIG. 12  shows an exploded view of the wiper module of  FIG. 11 . 
         FIG. 13  shows a perspective view of a different embodiment of a wiper module. 
         FIG. 14  shows interlocking a pair of the wiper modules of  FIG. 13 . 
         FIG. 15  shows an exploded view of the wiper modules of  FIG. 13  arranged on a shaft. 
         FIG. 16  shows the wiper modules of  FIG. 13  interlocked with one another on a shaft. 
         FIG. 17  shows a wiper blade with a protrusion for breaking large debris. 
         FIG. 18  shows the wiper blade of  FIG. 17  wiping a surface of a printhead. 
         FIG. 19  shows one embodiment of a capping module. 
         FIG. 20  shows a prior art scalable printhead array. 
         FIG. 21  shows a prior art printhead assembly and printhead. 
     
    
    
     DETAILED DESCRIPTION 
     For a general understanding of the environment for the maintenance system and maintenance cart disclosed herein, as well as the details for the maintenance system and maintenance cart, reference is made to the drawings. In the drawings, like reference numerals designate like elements. 
       FIG. 1  shows one embodiment of a maintenance system  300  for maintaining a scalable printhead array according to the present disclosure. The system  300  is configured to perform maintenance operations on a scalable printhead array  304  having a variable number of printheads, similar to the printhead array  100  shown in  FIG. 20 . In one embodiment, the printhead array  304  has printheads arranged in two scalable rows. The maintenance system  300  is similarly scalable to match the arrangement of printheads on the printhead array  304 . A pair of tracks  308  is arranged adjacent to the printhead array  304 . Shafts  312  extend between the tracks  308  and are configured to engage with each of the tracks  308  to move along the tracks  308 . A variable number of maintenance modules, including wiper modules  316  and capping modules  320  are mounted along the shafts  312  and configured to move along the tracks  308  with the shafts  312  to perform maintenance operations on the printheads of the printhead array  304 . 
     The tracks  308  are arranged in parallel to one another and on opposite ends of the printhead array  304 . In one embodiment, the tracks  308  run parallel to the process direction P of the printhead array  304  to enable the opposite ends of shafts  312  to move bi-directionally within the tracks  308 . In one embodiment, the tracks  308  run down a first side of the printhead array  304 , beneath the printhead array  304 , and up a second side of printhead array  304 , opposite the first side. In some embodiments, the tracks  308  are mounted to the printhead array  304 . In other embodiments, the tracks  308  are mounted to a frame of a printer having the printhead array  304 . 
     In some embodiments, the printhead array  304  includes a first row of printheads  324  and a second row of printheads  328 . Maintenance modules  316 ,  320  are arranged along the shafts  312  to match the arrangement of printheads in at least one of the rows of printheads  324 ,  328 . In some embodiments, the second row of printheads  328  has printheads arranged similarly to those of the first row of printheads  324 . In these embodiments, the shafts  312  are configured with an arrangement of maintenance modules that aligns with the printheads of either of the rows of printheads  324 ,  328 . In some embodiments, the second row of printheads  328  has printheads arranged similarly to those of the first row of printheads  324  but offset in the cross-process direction CP by a first distance. In one embodiment, the system  300  is configured to shift the maintenance modules  316 ,  320  in the cross-process direction CP by the first distance to enable the maintenance modules  316 ,  320  to perform maintenance operations on the second row of printheads  328 . 
       FIG. 2  shows a side view of one embodiment of the system  300 . In the embodiment shown, the track  308  is curved to guide the maintenance modules  316 ,  320  close to the first row of printheads  324  of the printhead array  304  and close to the second row of printheads  328 . The curve is configured to provide an ideal angle of approach and exit for the wiper modules  316 , so that debris is effectively wiped from the printheads without accidental flinging of the debris onto other components. 
       FIG. 2  shows the wiper modules  316  and the capping modules  320  in their respective resting positions  404 . When the maintenance modules  316 ,  320  are at the resting positions  404 , the printhead array  304  can operate normally, including performing printing operations. In one embodiment, when maintenance is performed, the printheads of the printhead array  304  first purge ink from inkjets of the printheads into a purge tray  408  positioned beneath the printhead array  304 . 
     Next, as shown in  FIG. 3 , the wiper modules  316  move from their respective resting positions  404  to the operating positions  412  at which the wiper modules  316  are configured to wipe a surface  416  of the first row of printheads  324  and a surface  420  of the second row of printheads  328 . In one embodiment, the wiper modules  316  have a wiper blade  332  configured to wipe against the surfaces  416 ,  420  of the rows of printheads  324 ,  328  as the wiper modules  316  move through the operating positions  412 . As shown in  FIG. 3 , two shafts  312  having wiper modules  316  are included. In one embodiment, each shaft  312  is configured with wiper modules  316  to align with one or both of the rows of printheads  324 ,  328 . However, in other embodiments, a single shaft  312  having wiper modules  316  is provided and configured to wipe both of the rows of printheads  324 ,  328 , one after the other. In some embodiments, the printhead array  304  is configured to selectively move toward the track  308  to enable the wiper blades  332  of the wiper modules to make contact with the surfaces  416 ,  420  of the rows of printheads  324 . 
     After the wiper modules  316  wipe the surfaces  416 ,  420  of the rows of printheads  324 ,  328 , the wiper modules  316  return to their respective resting positions  404 . In one embodiment, the printhead array  304  is configured to selectively move away from the track  308  to enable the wiper modules  316  to return to their respective resting position  404  without accidental contact with the printhead array  304 . In some embodiments, the system  300  includes a wiper cleaning device  336  configured to clean the wiper modules  316  after a wiping operation. The wiper cleaning device  336  includes a brush, foam, or an equivalent structure configured to wipe against the wiper blades  332  of the wiper modules  316  as they move along the track  308  to pass the wiper cleaning device  336 . In one embodiment, the wiper cleaning device  336  is positioned adjacent to the resting position  404  for the wiper modules  316  and is configured to wipe against the wiper blades  332  of the of the wiper modules  316  as they return to their resting positions  404 . 
     Next, as shown in  FIG. 4 , the capping modules  320  move from their respective resting positions  404  to the operating positions  412  from which the capping modules  320  are configured to perform a capping operation on the rows of printheads  324 ,  328  when the printhead array  304  is lowered towards the capping modules  320  at positions  412 . A capping operation refers to the covering of one or more printheads with a cap to seal the printhead face from ambient air to prevent the inkjets in the newly purged printheads from drying out before the next use of the printheads. In one embodiment, when the capping modules  320  are at the operating positions  412 , the printhead array  304  moves toward the track  308  to bring the capping modules  320  into contact with the surfaces  416 ,  420  of the rows of printheads  324 ,  328  to perform the capping operation. When the covered printheads are required for printing, the printhead array  304  is raised and the capping modules  320  return to their respective resting positions  404 . 
     As discussed above, in some embodiments, the second row of printheads  328  is misaligned with the first row of printheads  324  in the cross-process direction CP, such that the wiper modules  316  must shift in the cross-process direction CP to wipe the second row of printheads  328 . In some embodiments, the system  300  includes a bias bracket  340  positioned between the tracks  308  along the path of the shafts  312 , as shown in detail in  FIG. 5 . Bias blocks  344  are mounted on the shafts  312  and configured to slide along the shafts  312  to push the wiper modules  316  along the shaft in the cross-process direction CP. The bias bracket  340  is configured to engage with the bias blocks  344  as the shaft moves toward to operating position  412  corresponding to the second row of printheads  324 .  FIG. 6  shows one embodiment of the bias block  344  having a sloped surface  804  configured to engage with and slide along the bias bracket  340 . When the bias bracket  340  engages with a bias block  344 , the bias block  344  is moved along the shaft  312  in the cross-process direction CP and pushes against the wiper modules  316  to move them along the shaft  312  a first distance. In one embodiment, the first distance corresponds to the misalignment of the second row of printheads  328  with the first row of printheads  324  in the cross-process direction CP. In this way, the bias bracket  340  and bias block  344  are configured to move the wiper modules  316  into alignment with the printheads of the second row of printheads  328 . 
     In one embodiment, springs  348  are configured along the shafts  312  to push against the wiper modules  316  in a direction that is opposite the direction that the bias block  344  is moved by the bias bracket  340 . As the shafts  312  move past the bias bracket  340 , the bias block  344  disengages with the bias bracket  340 . After the bias block  344  disengages with the bias bracket  340 , the springs  348  push the wiper modules  316  to return them to a position that is in alignment with the printheads of the first row of printheads  324 . In the embodiment of  FIG. 5 , collars  352  are mounted on the shafts  312  to provide a stopping point corresponding to a position of the wiper modules  316  at which they are in alignment with the printheads of the first row of printheads  324 . 
     The maintenance modules  316 ,  320  are configured to be moved along the tracks  308  with a common drive mechanism. Although only depicted in  FIG. 1  and  FIG. 7 , an actuator, such as an electric motor  356 , can be provided in the various depicted embodiments to convey the shafts  312  having the maintenance modules  316 ,  320  along the tracks  308 . As shown in  FIG. 7 , the actuator is operatively connected to a chain or other endless drive (not shown), which is operatively connected to the shafts  312 . The actuator  356  can be operated to move the shafts  312  bi-directionally within the tracks  308 . 
       FIG. 7  shows a maintenance cart  900  having a maintenance system for maintaining a scalable printhead array, which is similar to the maintenance system  300  of  FIG. 1 . Similar components are labeled with similar reference labels. The cart  900  has a cart body  904  configured to move along a path to a printhead array  304  (shown in  FIG. 9 ). In one embodiment, the path is defined by a pair of rails  908 . The cart  900  includes a set of wheels  912  configured to roll along the rails  908  to guide the cart body  904  to and from a printhead array  304 . In one embodiment, the rails  908  are also used by a printing platform that conveys a substrate to the printhead array  304  for printing operations. 
     The cart  900  includes a pair of tracks  308  mounted to the cart body  904 . The tracks  308  run in parallel with one another on opposite sides of the cart. In one embodiment, as shown in  FIG. 7 , the tracks  308  run in the process direction P and around the cart body  904  to form a closed loop. The cart  900  includes shafts  312  having maintenance modules  316 ,  320  that are configured to move along the tracks  308  to perform maintenance operations on the printhead array  304 . In some embodiments, a bias bracket  340 , bias blocks  344 , springs  348 , and collars  352  are provided and operate as described with respect to the system  300 . Additionally, a purge tray  408  is mounted to the cart body  904  and configured to receive purged ink from the printhead array  304  during maintenance operations.  FIG. 8  shows a front view of the cart  900 . As shown in  FIG. 8 , in some embodiments, the cart  900  may include a wiper cleaning device  336  mounted to an underside of the cart body  904 . 
       FIG. 9  shows a side view of the cart  900 . As shown, the maintenance modules  316 ,  320  are positioned at resting positions  404  to enable the printhead array  304  to operate normally and to purge ink into the purge tray  408 . To perform maintenance on the printhead array  304 , the maintenance modules  316 ,  320  move to the operating positions  412  from which the maintenance modules  316 ,  320  are configured to perform maintenance operations on the printhead array  304 . In  FIG. 9 , the rails  908  are not depicted to simplify the presentation. 
       FIG. 10  shows a different embodiment of the maintenance cart  900 . In the embodiment shown, the cart  900  includes guides  1204  configured to mount onto the rails  908  (not shown) to move along the rails  908  to and from the printhead array  304  (not shown). A cart body  904  has a continuous perimeter that forms a recess  1208  within the perimeter. Tracks  308  are mounted on opposite sides of the recess  1208  and configured to guide a shaft  312  having wiper modules  316  from a resting position  404  to operating positions  412  to enable the wiper modules  316  to wipe debris from printheads of the printhead array  304 . In some embodiments, the tracks  308  include at least one cut-out  1212  configured to allow the shafts  312  to be removed from the tracks  308 . In some embodiments, a bias bracket  340 , bias blocks  344 , springs  348 , and collars  352  are provided and operate as described with respect to the system  300 . Additionally, a purge tray is mounted within the recess  1208  of the cart body  904  and configured to receive purged ink from the printhead array  304  during maintenance operations. In one embodiment, capping modules  320  are mounted on stationary shafts  1216 . The shafts  1216  extend across the recess  1208  and are mounted within the recess  1208  with mounts  1220 . The mounts  1220  are configured to allow the shafts  1216  to be removed. The cart  900  is configured to move along the rails  908  to align the capping modules  320  with printheads of the printhead array  304  to enable the capping modules  320  to perform capping operations on the printheads of the printhead array  304 . 
       FIG. 11  shows a wiper module  1300 , which is one embodiment of the wiper modules  316 . The wiper module  1300  has a lid  1304  and a base  1308 . The lid  1304  and the base  1308  are configured to join together around the shafts  312 .  FIG. 12  shows an exploded view of the wiper module  1300 , demonstrating how the lid  1304  and the base  1308  join together around the shafts  312 . The shafts  312  fit into cut-outs  1312  in the lid  1304  and base  1308 . The cut-outs  1312  are configured to allow the wiper module  1300  to slide freely along the shafts  312 . Magnets  1316  are provided in the lid  1304  and the base  1308  and configured to removably connect the lid  1304  to the base  1308 . In this way, the wiper module  1300  is configured to be easily mounted to or removed from the shafts  312 , without detaching the shafts  312  from the tracks  308 . 
     A wiper blade  1320  is mounted to a surface  1324  of the lid  1304 , which is opposite a surface of the lid  1304  that joins with the base  1308 . In one embodiment, the wiper blade  1320  is made of a rigid material, such as metal, and includes a wiper tip  1328  made of a soft material, such as rubber. The wiper tip  1328  is configured to make contact with and wipe against a surface of a printhead of the printhead array  304 . In one embodiment, the wiper blade  1320  is mounted to the surface  1324  of the lid  1304  at an acute angle. In one embodiment, the wiper blade  1320  has a width that is about equal to a width of the wiper module  1300 . In one embodiment, the width of the wiper blade  1320  corresponds to a width of surface of a printhead of the printhead array  304 . 
       FIG. 13  shows a wiper module  1500 , which is another embodiment of the wiper modules  316 . The wiper module  1500  has a body  1504  that is configured to mount onto shafts  312  (shown in  FIG. 15 ). A wiper blade  1508  is mounted on a surface  1512  of the body  1504 . In one embodiment, the wiper blade  1508  is made of a rigid material, such as metal, and includes a wiper tip  1516  made of a soft material, such as rubber. The wiper tip  1516  is configured to make contact with and wipe against a surface of a printhead of the printhead array  304 . In one embodiment, the wiper blade  1508  is mounted to the surface  1512  at an acute angle. In one embodiment, the width of the wiper blade  1508  corresponds to a width of surface of a printhead of the printhead array  304 . In one embodiment, the wiper module  1500  has a width that corresponds to a width of a printhead assembly that holds a printhead of the printhead array  304 . 
     The wiper module  1500  includes holes  1520  that extend through the body  1504  from first end to an opposite second end and are configured to receive the shafts  312 . At the first end of the body  1504 , the holes  1520  have collar portions  1524 . At the second end of the body  1504 , the holes  1520  have counter-bored portions  1528 , as shown in  FIG. 14 . The collar portions  1524  are configured to interlock with the counter-bored portions  1528  of another wiper module  1500 .  FIG. 15  shows an exploded view of several wiper modules  1500  arranged on shafts  312 . In one embodiment, a bias block  344 , springs  348 , and collars  352  are also arranged on the shafts  312  as described with respect to the system  300 .  FIG. 16  shows the wiper modules  1500  arranged on the shafts  312  and interlocked with one another. 
       FIG. 17  shows a wiper blade  1900 , which, in some embodiments, is used in conjunction with one of the wiper module embodiments discussed above. The wiper blade  1900  is mounted atop a body of a wiper module  316  (not shown). The wiper blade  1900  includes a holder  1904 . The holder  1904  is configured to receive a pair of plates  1908  and a wiper portion  1912 . The wiper portion  1912  is configured to interlock between the pair of plates  1908 , and to extend out from the pair of plates  1908  in a first direction. The interlocked wiper portion  1912  and the pair of plates  1908  are configured to slide laterally into an interlocked position with the holder  1904 . The holder  1904  has a protrusion  1916  that protrudes in the first direction near the wiper portion  1912 . The wiper portion  1912  extends in the first direction further than the protrusion  1916  extends in the first direction. In one embodiment, the protrusion  1916  is made of a rigid material, such as metal, and the wiper portion  1912  is made of a soft material, such as rubber. As shown in  FIG. 18 , as the wiper blade  1900  wipes against a surface  2004  of a printhead  2008 , the protrusion  1916  breaks away large debris  2012  from the surface  2004  before the wiper portion  1912  wipes against the surface  2004 . The protrusion  1916  does not come into contact with the surface  2004 , but only breaks away the large debris  2012  to allow the wiper portion  1912  to wipe the surface  2004  more effectively. 
       FIG. 19  shows a capping module  2100 , which is one embodiment of the capping modules  320 . The capping module  2100  has a body  2104  that is configured to slide onto shafts  312 . In one embodiment, the body  2104  has a base  2108  and a lid  2112  that are configured to join together around the shafts  312 . The capping module  2100  includes a capping surface  2116 . In one embodiment, the capping surface is molded plastic. In the depicted embodiment, the body  2104  has a width corresponding to a width of a printhead assembly and the capping surface  2116  has a width corresponding to surface of a printhead of the printhead assembly. When the capping module  2100  is aligned with a printhead, the capping surface  2116  presses against a surface of the printhead to perform a capping operation on the printhead. In one embodiment, the capping module  2100  has springs  2120  configured to bias the capping surface  2116  towards the surface of the printhead. 
     It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems, applications or methods. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art, which are also intended to be encompassed by the following claims.