Patent Publication Number: US-8118392-B2

Title: Movable web support and cap

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     The present application is related to co-pending U.S. patent application Ser. No. 12/200,927 filed on the same date herewith by Tanya V. Burmeister, Antonio Gomez and Mark D. Groenenboom and entitled WEB, the full disclosure of which is incorporated by reference. 
     BACKGROUND 
     Print head servicing stations sometimes include webs and caps for servicing the print heads. Size objectives sometimes limit a size of the web, necessitating more frequent and costly replacement of the web. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a printing system according to an example embodiment. 
         FIG. 2  is a sectional view of the printing system of  FIG. 1  taken along line  2 - 2  according to an example embodiment. 
         FIG. 3  is a sectional view of the printing system of  FIG. 1  taken along line  3 - 3  illustrating ejection of fluid onto a web according to an example embodiment. 
         FIG. 4  is a sectional view of the printing system of  FIG. 1  taken along line  3 - 3  illustrating wiping of print heads by the web according to an example embodiment. 
         FIG. 5  is a sectional view of the printing system of  FIG. 1  taken along line  3 - 3  illustrating capping of the print head according to an example embodiment. 
         FIG. 6  is a flow diagram of a method for servicing a print head according to an example embodiment. 
         FIG. 7  is a perspective view of another embodiment of the printing system of  FIG. 1  according to an example embodiment. 
         FIG. 8  is a bottom perspective view of a service station of the printing system of  FIG. 7  according to an example embodiment. 
         FIG. 9  is a top perspective view of a portion of the printing system of  FIG. 7  according to an example embodiment. 
         FIG. 10  is a side elevational view of a web support of the printing system of  FIG. 7  in a raised position according to an example embodiment. 
         FIG. 11  is a side elevational view of a web support of the printing system of  FIG. 7  in a lowered position according to an example embodiment. 
         FIG. 12  is a side elevational view of a cap of the printing system of  FIG. 7  in a first retracted position according to an example embodiment. 
         FIG. 13  is a side elevational view of the printing system of  FIG. 7  with the cap in a second extended position according to an example embodiment. 
         FIG. 14  is a perspective view of the printing system of  FIG. 7  with the web support in the lowered position and the cap in the second extended position according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
       FIGS. 1-3  schematically illustrate printing system  10  according to one exemplary embodiment. Printing system  10  generally includes drum  12 , rotary actuator  13 , media supply  14 , media output  16 , print heads  18 , carriage  20 , actuator  21 , service station  22  and controller  24 . Drum  12  generally comprises an elongated cylinder configured to be rotationally driven about axis  26  by rotary actuator  13  while transporting media, such as paper, about axis  26  relative to print heads  18 . Rotary actuator  13  comprises a source of torque, such as a motor, operably coupled to drum  12  by a transmission (not shown). 
     Media supply  14 , schematically shown, comprises a mechanism configured to supply media to drum  12 . In one embodiment, media supply  14  comprises a mechanism configured to pick an individual sheet of media from a stack of media and to supply the individual sheet to drum  12  such that the sheet is wrapped at least partially about drum  12 . Media output  16 , schematically shown, comprises a mechanism to withdraw printed upon media from drum  12  and to transport withdrawn media to and contain withdrawn media within an output tray, bin or the like. 
     Print heads  18  comprise devices configured to dispense imaging material or fluid, such as ink, upon the medium held by drum  12 . In one embodiment, print heads  18  comprise piezo electric print heads. In another embodiment, print heads  18  comprise thermal inkjet print heads. As shown by  FIG. 2 , print heads  18  are arranged in an arc about axis  26 . As a result, print heads  18  are configured to print across a larger area of the media supported by drum  12 . In the particular embodiment, drum  12  has an outer surface  30  also arranged in an arc about axis  26 . Print heads  18  are arranged in an arc substantially identical to the arc in which surface  30  extends. 
     Carriage  20  comprises one or more structures configured to support print heads  18  in the arcuate arrangement. In addition, carriage  20  is configured to movably support print heads  18  along axis  26 . Actuator  21  comprises a linear actuator configured to move carriage  20  and print heads  18  in the directions indicated by arrows  27 ,  28  so as to selectively position print heads  18  opposite to the media held by drum  12  or opposite to service station  22 . In one embodiment, actuator  21  may comprise a motor configured to drive a toothed pulley in engagement with a toothed belt coupled to carriage  20 . In another embodiment, actuator  21  may comprise other forms of a linear actuator using rack and pinion arrangements, hydraulic, pneumatic or electrical means. Although system  10  is illustrated as including five print heads supported by a single carriage  20 , system  10  may alternatively include a greater or fewer number of such print heads  18  supported by one or more carriages  20 . For example, in another embodiment, a separate carriage  20  may be provided for each print head  18 . 
     Service station  22  comprises a station located on an axial end of drum  12  such that carriage  20  may position print heads  18  opposite, or adjacent, to station  22 . Station  22  includes one or more components configured to perform servicing operations upon one or more of the print heads  18 . As shown by  FIGS. 1-3 , in the particular example shown, service station  22  further includes a frame  30 , supply spool  32 , take-up spool  34 , web drive  36 , web  38 , track or web support  44 , lifters  46 , actuator  47  caps  48  and actuator  50 . Frame  30  comprises one or more walls, panels, structures, frame members and the like configured to support supply spool  32 , take-up spool  34 , web drive  36 , web  38 , track or web support  44 , lifters  46 , caps  48  and actuator  50  relative to drum  12 . 
     Supply spool  32  comprises a reel configured to carry multiple windings of web  38  and to supply web  38  for use by service station  22 . Take-up spool  34  comprises a reel configured to receive used windings of web  38 . Web drive  36  comprise a mechanism configured to rotationally drive take-up spool  34  so as to move web  38  from spool  32  to spool  34 . In one embodiment, web drive  36  may comprise motor operably coupled to spool  34  by a transmission such as a gear train, a belt and pulley arrangement or a chain and sprocket arrangement. As shown by  FIG. 2 , web  38  is supported by web support  44  between spools  32  and  34 . 
     In the example illustrated, spools  32  and  34  have vertically overlapping diameters. In other words, spools  32  and  34  at least partially vertically overlap one another. In particular, spools  32  and  34  are arranged such that web  38  travels in a first direction from spool  32 , travels through a U-turn and returns to spool  34  by traveling in a second direction generally opposite to the first direction. Spools  32  and  34  are located on a same side of web support  44 . Because spools  32  and  34  have diameters that at least partially overlap, space is better utilized, allowing a larger amount of web  38  to be compactly stored until use. As a result, service station  22  may operate for longer periods of time without replacement of web  38 . Although take-up spool  34  is illustrated as being located over supply spool  32 , in other embodiments, this relationship may be reversed. In still other embodiments, spools  32  and  34  may alternatively be located on opposite sides of web support  44 . 
     In the example illustrated, supply spool  32  is removably coupled to frame  30 , allowing spool  32  to be separated from frame  30 . As a result, spool  32  is only removed and replaced upon consumption of web  38 . In other embodiments, spools  32  and  34  may alternatively be provided as part of a cartridge, wherein the entire cartridge is removed or swapped upon consumption of web  38 . 
     Web  38  comprises a band or span of material for performing servicing operations upon print heads  18 . In one embodiment, web is configured to interact with print heads  18  by receiving fluid, printing material or ink discharged from print heads  18 . For example, in one embodiment, print heads  18  include multiple nozzles. Web  38  facilitates spitting of ink from the nozzles to clear such nozzles. In the embodiment illustrated, web  38  comprises a web of material configured to physically contact the surfaces of print heads  18  so as to wipe print heads  18 . In the particular example illustrated, web  38  is also configured to contact the surfaces of print heads  18  as carriage  20  moves print heads  18  along axis  26  relative to web  38  to wipe print heads  18 . In other embodiments, web  38  may additionally be configured to be moved relative to print heads  18  to perform such wiping operations. In one embodiment, web  38  comprises a web of fluid absorbent material. In one embodiment, web  38  comprises a fabric material. According to one embodiment, web  38  is formed from a fabric material such as Evolon 100 commercially available from Freudenberg Group of Germany. 
     In one embodiment, web  38  includes non-absorbent regions  52  separating or isolating different absorbent regions  53  from one another. Non-absorbent regions  52  inhibit migration of fluid between adjacent absorbent regions  53 . Non-absorbent regions  52  inhibit migration of fluid deposited during spitting in one absorber region to other absorbent regions which are used for wiping. As a result, non-absorbent regions  52  prevent cross-contamination and increase or prolong the useful life of web  38 . 
     As shown by  FIG. 2 , web support  44 , schematically shown, comprises one or more structures configured to support and guide web  38  in an arc about axis  26 . In the particular example shown, web support  44  is configured to support web  38  about an arc substantially similar to the arc along which print heads  18  are arranged. In one embodiment, web support  44  comprises an elongate arcuate panel or surface underlying web  38 . In yet another embodiment, web support  44  comprises multiple individual surfaces that are spaced from one another in an arc. For example, in one embodiment, web support  44  may be formed from multiple rollers extending in the arc. 
     Web support  44  is movably coupled to frame  30  so as to move between a raised position (shown in  FIGS. 1-3 ) for servicing print heads  18  and a retracted or lowered position (shown in  FIG. 5 ) facilitating the capping of print heads  18 . In one embodiment, web support  44  is pivotally coupled to frame  30 . For example, in the embodiment illustrated, web support  44  is pivotally coupled to frame  30  about a pivot axis  51 . In other embodiments, web support  44  may be pivotally coupled to frame  30  about other pivot axes. In still other embodiments, web support  44  may alternatively be configured to translate or slide between the raised position and the lowered position such as along one or more vertical tracks, channels or grooves. 
     In the particular example illustrated, web support  44  includes a bottom support  54  and a top cover or panel  56 . Bottom support  54  extends below web  38  while top panel  56  extends over web  38  so as to sandwich and contain web  38 . Top panel  56  includes windows  57  which expose portions of web  38 . In other embodiments, top panel  56  may be omitted. Because web support  44  supports web  38  in an arc, web  38  may be used to simultaneously service multiple print heads  18 . As shown by  FIGS. 1 and 3 , web  38  is supported by web support  44  over lifters  46  in an arc. As shown by  FIG. 1 , web  38  is exposed through windows  57 . A portion of web  38  overlays lifters  46  so that web  38  may be raised into contact with print heads  18  during servicing of print heads  18 . 
     Lifters  46  comprise mechanisms configured to lift or elevate selected portions of web  38  and to press or hold such elevated portions of web  38  against opposite portions of print heads  18  to facilitate wiping of print heads  18 . In the example illustrated, each of lifters  46  includes a web backer  58  and an actuator  60 . Web backer  58  comprises a structure configured to move between (1) a raised position in which web backer  58  contacts an underside of web  38  and lifts the opposing portion of web  38  to a height sufficient to contact an associated opposing print head  18  and (2) a lower position in which web  38  is spaced from print heads  18 . In one embodiment, in a raised position, web backer  58  supports web  38  above web support  44  and in the lowered position allows web  38  to rest upon bottom support  54  of web support  44 . In one embodiment, web Backer  58  comprises a resiliently compliant member, such as a sponge or foam member. In other embodiments, web backer  58  may have other configurations and may be formed from other materials. 
     Actuator  60  comprises a mechanism configured to selectively move web backer  58  between the raised and the lowered positions. In one embodiment, actuator  60  may comprise one or more cams driven by a motor or other power sources. In another embodiment, actuator  60  may comprise electric solenoids, pneumatic or hydraulic cylinder assemblies or other actuation mechanisms which directly interact with web backer  58  or which drive an intermediate cam which facilitates movement of web backer  58 . In other embodiments where other mechanisms are provided for wiping of print heads  18  and where web  38  is merely used to receive fluid ejected from print heads  18 , such as during spitting or purging operations, lifters  46  may be omitted. 
     Actuator  47  comprises a mechanism configured to move web support  44  and the supported web  38  between the raised position and the lowered position. In the raised position, web support  44  and web  38  are appropriately positioned to facilitate servicing of print heads  18 . In the lowered position, web support  44  and web  38  are sufficiently retracted from print heads  18  or lowered with respect to print heads  18  to permit insertion of caps  48  between web  38  and print heads  18 . Such raising and lowering of web support  44  permits caps  48  and web  38  to share vertical space, providing a more compact design and potentially enabling web  38  to be provided with an increased width. The increased width of web  38  increases the fluid absorption capacity of web  38  and enables service station  22  to operate for longer times without replacement of web  38 . 
     In the example illustrated, actuator  47  is configured to pivot web support  44  about axis  51  between the raised position and the lowered position. In other embodiments, actuator  47  may be configured to translate or slide web support  44  between the raised position and the lowered position. In other embodiments, web support  44  may be both pivoted and translated between the raised and lowered positions. 
     According to one embodiment, actuator  47  may comprise one or more cams which are datumed directly to or about the rotational axis  26  of drum  12 . In other words, the one or more cams of actuator  47  have surfaces that directly contact surfaces (called datum surfaces) of one or more members that define the rotational axis  26  of drum  12 . The datum surfaces precisely locate the one or more cams of actuator  47  with respect to the rotational axis  26 . Such cams operably engage cam followers associated with web support  44  to raise and lower web support  44 . Such cams are operably coupled to a motor by a transmission such as a gear train, a belt and pulley arrangement or a chain and sprocket arrangement. Because such cams are datumed directly to the rotational axis  26  of drum  12  (shown in  FIG. 1 ) by being directly mounted to the same structures that locates drum axis  26  and rotates about axis  26 , tolerance stack may be reduced or minimized. In one embodiment, actuator  60  also comprises cams which engage cam followers associated with lift members  58 , wherein the cams of actuator  60  are also datumed directly to drum axis  26 , further reducing tolerance stack. In other embodiments, actuator  47  may comprise other members configured to move web support  44 , such as hydraulic or pneumatic cylinder-piston assemblies, electric solenoids and the like. 
     Caps  48  comprise structures configured to cap or seal about fluid nozzle openings of print heads  18 . Caps  48  seal about such nozzle openings when print heads  18  are not in use. Caps  48  reduce or slow drying of fluid of print heads  18  to maintain moisture about the nozzle openings of print heads  18  which enhances health of the print heads  18 . In some embodiments, caps  48  may additionally be configured to provide for purging of fluid from print heads  18 . 
     In the example illustrated, caps  48  are coupled or connected to one another so as to move in unison with one another. Caps  48  move between a first position at least partially withdrawn from over and above web support  44  (shown in  FIGS. 1 and 3 ) and a second position over and above web support  44  to a greater extent as compared to the first position. In the example illustrated, in the first position, caps  48  are completely withdrawn from over and above web  38 . In the second position, caps  48  project above and over web  38  by a distance of at least 25 mm and nominally about 38 mm in a direction along axis  26 . 
     As noted above, caps  48  are configured to move to the second position when web support  44  is in the lowered position. Because caps  48  share space with web support  44  and web  38 , servicing station  22  is more compact and web  38  may be provided with a greater width. As a result, the absorptive capacity of web  38  may be increased to increase the useful life of web  38 . 
     In the example illustrated, caps  48  are arranged in an arc about axis  26 . As a result, caps  48  may be more easily moved to the second position in which caps  48  are located between web  38  and print heads  18 . In other embodiments, caps  48  may have other arrangements. In other embodiments, caps  48  may move independent of one another 
     Actuator  50  comprises a mechanism configured to move caps  48  between the first position and the second position. In particular, actuator  50  moves caps  48  along axis  26 . In one embodiment, actuator  50  is configured to additionally move caps  48  in a direction substantially perpendicular to axis  26  so as to raise caps  48  into the sealing engagement with print heads  18 . In other embodiments, separate actuators may be used to raise and lower caps  48  with respect to print heads  18 . In yet other embodiments, caps  48  may merely move along axis  26 , wherein print heads  18  are raised and lowered with respect to caps  48  for capping of print heads  18 . 
     In one example embodiment, actuator  50  may comprise a series of linkages and/or arms configured to receive motion or force from carriage  20  and to transmit such force or motion to caps  48  so as to move caps  48  between the first position and the second position. For example, in one embodiment, actuator  50  may be configured to be engaged by carriage  20  as print heads  18  are moved leftward as seen in  FIG. 1 . Actuator  50  is configured to transmit motion to caps  48  to move caps  48  rightward as seen in  FIG. 1 . Upon subsequent movement of carriage  20  rightward as seen in  FIG. 1 , caps  48  may return to the first position, moving leftward as seen in  FIG. 1 , under the force supplied by a bias, such as a spring. In other embodiments, actuator  50  may comprise other actuation mechanisms such as a motor and can arrangement, a hydraulic or pneumatic cylinder-piston assembly or an electric solenoid. In other embodiments, caps  48  may alternatively be configured to move along axis  26  between a first position and the second position independent of one another. 
     Controller  24  comprises one or more processing units configured to generate control signals directing the operation of printing system  10 . Controller  24  may be associated with printer  10  or in some embodiments, may be associated with a peripheral computing device connected to printer  10 . Controller  24  generates control signals directing the positioning of media by media supply  14  and rotation of drum  12  by rotary actuator  13 , directing the positioning of print heads  18  through movement of carriage  20  by actuator  21 , directing the ejection of fluid by print heads  18 , and directing the servicing of print heads  18  at service station  22 . 
     With respect to service station  22 , controller  24  tracks operation of web drive  36  to control the supply of web  38 . Controller  24  generates control signals directing operation of actuators  47  and  60  to provide spitting, wiping and capping servicing operations. Controller  24  also generates control signals directing operation of actuator  50 . In some embodiments in which actuator  50  transmits motion or force received from movement of carriage  20  to caps  48 , controller  24  controls positioning of caps  48  through its control of actuator  21  which moves carriage  20 . 
     Controller  24  is coupled to rotary actuator  13 , media supply  14 , print heads  18 , actuator  21 , web drive  36 , actuators  47  and  60  and actuator  50  (where applicable) in a wired fashion or in a wireless fashion. For purposes of this application, the term “processing unit” shall mean a presently developed or future developed processing unit that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processing unit 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. For example, controller  24  may be embodied as part of one or more application-specific integrated circuits (ASICs). Unless otherwise specifically noted, the controller 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. 3-5  schematically illustrate service station  22  during different servicing operations upon print heads  18  (one of which is shown).  FIG. 3  illustrates service station  22  during spitting operations. As shown by  FIG. 3 , in response to control signal from controller  24 , actuator  47  has positioned web support  44  in the raised position. At the same time, actuator  60 , in response to control signal from controller  24  has lowered web backers  58  to lowered positions. Actuator  21  (shown in  FIG. 1 ), in response to control signals from controller  24  locates carriage  20  and print heads  18  opposite to web  38 . Controller  24  further generates control signals directing print heads  18  to spit fluid onto web  38 . During such spitting, caps  48  are in the first position, withdrawn from over and above web  38 . 
       FIG. 4  illustrates service station  22  during a wiping operation. During the wiping operation, web support  44  is in the raised position and caps  48  are in a first retracted position. However, as shown by  FIG. 4 , in response to control signal from controller  24  (shown in  FIG. 1 ), actuators  60  move web backers  58  to raised positions in which web backers  58  lift and elevate web  38  into contact with the nozzles of print head  18  for wiping of print head  18 . In one embodiment, controller  24  (shown in  FIG. 1 ) further generates control signals directing actuator  21  (shown in  FIG. 1 ) to translate print heads  18  relative to web backers  58  while web backers  58  are in the raised position to effectuate wiping. 
       FIG. 5  illustrates service station  22  in a capping operation or state. As shown by  FIG. 5 , controller  24  (shown in  FIG. 1 ) generates control signals such that actuator  60  moves or maintains web backers  58  in the lowered position. Controller  24  generates control signals directing actuator  47  to move web support  44  in the direction indicated by arrow  63  to the lowered position. Web support  44  is lowered by a distance sufficient to permit one or more of caps  48  to be positioned between or sandwiched between print heads  18  and web  38 . In one embodiment, web support  44  is lowered by distance equal to or greater than a height of caps  48 . In one embodiment, web support  44  is lowered by distance of at least 14 mm. 
     As noted above, in one embodiment, actuators  47  and  60  comprise cams. In one embodiment, such cams may be supported on a single relational drive member so as to rotate with one another. Rotation of the rotational drive member by a motor or other rotational drive arrangement is controlled by controller  24 , wherein different angular positions of such cams result in web backers  58  being raised or lowered and/or web support  44  being raised or lowered. 
     As further shown by  FIG. 5 , controller  24  generates control signals directing actuator  50  to move caps  48  in the direction indicated by arrow  65  from the first position shown in  FIGS. 3 and 4  to the second position shown in  FIG. 5 . In one embodiment, caps  48  are linearly translated to the second position shown in  FIG. 5 . 
     Once caps  48  are in the second position between web  38  and print head  18 , one or both of print head  18  and caps  48  are moved towards one another until caps  48  are in capping or sealing engagement with print head  18 . In one embodiment, caps  48  are raised into engagement with print head  18 . In one embodiment, such raising of caps  48  is also achieved by actuator  50 . In embodiments where actuator  50  comprises a series of linkages, arms or cams which transmit force or motion from movement of carriage  22  so as to move caps  48 , controller  24  controls the positioning of caps  48  by controlling the position of carriage  20  with actuator  21  (shown in  FIG. 1 ). 
       FIG. 6  is a flow diagram illustrating a method  100  of servicing print heads  18 . As indicated by step  110 , web support  44  is moved to the raised position (shown in  FIG. 3 ). If web support  44  is already in the raised position, such movement may be omitted. As indicated by step  112  and also shown by  FIG. 3 , fluid, such as ink, is spit or otherwise ejected from print head  18  onto web  38 . Such spitting is schematically represented by arrows  113  in  FIG. 3 . Such spitting clears nozzles of print heads  18 . 
     As indicated by step  114  and shown in  FIG. 4 , web backers  58  are moved to their raised positions. As noted above, such movement results in web  38  being moved or pressed against print head  18 . As indicated by step  116 , print heads  18  are wiped. In particular, carriage  20  is moved so as to move print heads  18  relative to web  38  and web supports  58  while web  38  is in contact with print heads  18 . During such wiping, before such wiping or after completion of wiping, controller  24  may generate control signals directing web drive  36  (shown in  FIG. 2 ) to advance web  38  to present a fresh or clean portion of web  38  opposite to print head  18  for current wiping or subsequent wiping operations. 
     As indicated by step  118  and shown in  FIG. 5 , web backers  58  and web support  44  are both lowered to their lowered positions. In the embodiment illustrated, prior to such lowering, caps  48  have a height greater than the spacing between web  38  and print heads  18  which would otherwise inhibit positioning of caps  48  between print heads  18  and web  38 . As indicated by step  120 , caps  48  are moved between web  38  and print head  18 . Caps  38  are moved to a positions opposite to and in substantial alignment with print head  18  such that sealing portions of caps  48  surround nozzle openings (not shown) of print heads  18 . As indicated by step  122 , print heads  18  are capped. In particular, print heads  18  and caps  48  are moved into sealing engagement with one another. In one embodiment, caps  48  are raised into engagement with nozzle faces of print head  18 . 
       FIGS. 7-9  illustrate printing system  210 , another embodiment of printing system  10  shown in  FIG. 1 . Printing system  210  generally includes drum  212 , rotary actuator  213 , media supply  214 , media output  216 , print heads  218  (one of which is shown), carriages  220  (one of which is shown), actuators  221  (one of which is shown) service station  222  and controller  224  (shown in  FIGS. 7 and 9 ). Drum  212  generally comprises an elongated cylinder configured to be rotatably driven about axis  226  by rotary actuator  213  while transporting media, such as paper, about axis  226  relative to print heads  218 . Rotary actuator  213 , schematically shown, comprises a source of torque, such as a motor, operably coupled to drum  212  by a transmission (not shown). 
     Media supply  214 , schematically shown, comprises a mechanism configured to supply media to drum  212 . In one embodiment, media supply  214  comprises a mechanism configured to pick an individual sheet of media from a stack of media and to supply the individual sheet to drum  212  such that the sheet is wrapped at least partially about drum  212 . Media output  216 , schematically shown, comprises a mechanism configured to withdraw printed upon media from drum  212  and to transport withdrawn media to and contain withdrawn media within an output tray, bin or the like. 
     Print heads  218  comprise print heads configured to dispense imaging material, such as ink, upon the medium held by drum  212 . In one embodiment, print heads  218  comprise piezo electric print heads. In another embodiment, print heads  218  comprise thermal inkjet print heads. Print heads  218  are arranged in an arc about axis  226 . As a result, print heads  218  are configured to print across a larger area of the media supported by drum  212 . In the particular embodiment, drum  212  has an outer surface  230  also arranged in an arc about axis  226 . Print heads  218  are arranged in an arc substantially identical to the arc in which surface  230  extends. 
     Carriage  220  comprises one or more structures configured to support print heads  218  in the arcuate arrangement. In addition, carriage  220  is configured to movably support print heads  218  along axis  226 . Actuator  221  comprises a linear actuator configured to move carriage  220  and print heads  218  so as to selectively position print heads  218  opposite to the media held by drum  212  or opposite to service station  222 . In one embodiment, actuator  221  may comprise a motor (not shown) configured to drive a toothed pulley in engagement with a toothed belt coupled to carriage  220 . In another embodiment, actuator  221  may comprise other forms of a linear actuator using rack and pinion arrangements, hydraulic, pneumatic or electrical means. Although only one print head  218 , carriage  220  and actuator  221  is shown, in the example illustrated, system  210  includes 6 print heads supported by 6 carriages, wherein each print head  218  is independently moved or actuated by a dedicated actuator  221 . In other embodiments, a single carriage may move each of the multiple print heads in unison with one another. In other embodiments, system  210  may alternatively include a greater or fewer of such print heads  218  supported by one or more carriages  220  and driven by one or more actuators  221 . 
     Service station  222  comprises a station located on an axial end of drum  212  such that carriages  220  may position print heads  218  opposite, or adjacent, to station  222 . Station  222  includes one or more components configured to perform servicing operations upon one or more of the print heads  218 . As shown by  FIG. 8 , in the particular example shown, service station  222  includes a frame  230 , supply spool  232 , take-up spool  234 , web drive  236 , web  238 , track or web support  244 , lifters  246 , actuator  260 , caps  248  and actuator  250 . Frame  230  comprises one or more walls, panels, structures, housing members and the like configured to support supply spool  232 , take-up spool  234 , web drive  236 , web  238 , track or web support  244 , lifters  246 , caps  248  and actuator  250  relative to drum  212 . 
     Supply spool  232  comprises a reel configured to carry multiple windings of web  238  and to supply web  238  for use by service station  222 . Take-up spool  234  comprises a reel configured to receive used windings of web  238 . Web drive  236  comprises a mechanism configured to rotationally drive take-up spool  234  so as to move web  238  from spool  232  to spool  234 . In the embodiment illustrated, web drive  236  comprises a motor  300  (shown in  FIG. 8 ) operably coupled to spool  234  by a transmission  302  comprising a gear train. In other embodiments, transmission  302  may comprise a belt and pulley arrangement or a chain and sprocket arrangement. As shown by  FIG. 8 , web  238  is supported by web support  244  between spools  232  and  234 . 
     In the example illustrated, spools  232  and  234  have vertically overlapping diameters. In other words, spools  232  and  234  at least partially vertically overlap one another. In particular, spools  232  and  234  are arranged such that web  238  travels in a first direction from spool  232 , travels through a U-turn and returns to spool  234  by traveling in a second direction generally opposite to the first direction. Spools  232  and  234  are located on a same side of web support  244 . Because spools  232  and  234  have diameters at least partially overlap, is better utilized, allowing a larger amount of web  238  to be compactly stored until use. As a result, service station  222  may operate for longer periods of time without replacement of web  238 . Although take-up spool  234  is illustrated as being located over supply spool  232 , in other embodiments, this relationship may be reversed. In still other embodiments, spools  232  and  234  may alternatively be located on opposite sides of web support  244 . 
     In the example illustrated, supply spool  232  is removably coupled to frame  230 , allowing spool  232  to be separated from frame  230 . As a result, spool  232  is only removed and replaced upon consumption of web  238 . In other embodiments, spools  232  and  234  may alternatively be provided as part of a cartridge, wherein the entire cartridge is removed or swapped upon consumption of web  238 . 
     Web drive  236  comprises a mechanism configured to drive one or both of supply spool  232  or take-up spool  234  so as to move web  238  across web support  244  and across windows  257 . Web drive  236  drives web  238  over web backers  258 . In the example illustrated, web drive  236  comprises a transmission, such as the set of drive gears shown, connected to the take-up spool  234  and operably coupled to motor  300  (shown in  FIG. 8 ). Torque supplied by the motor  300  drives take-up spool  234  to pull web  238  from supply roll or spool  232  about web support  244  to take-up spool  234  as indicated by arrows  306  in  FIG. 8 . In other embodiments, web drive  236  may have other configurations. 
     Web  238  comprises a band or span of material for performing servicing operations upon print heads  218 . In one embodiment, web is configured to interact with print heads  218  by receiving fluid, printing material or ink discharged from print heads  218 . For example, in one embodiment, print heads  218  include multiple nozzles (not shown). Web  238  facilitates spitting of ink from the nozzles to clear such nozzles. In the embodiment illustrated, web  238  comprises a web of material configured to physically contact the surfaces of print heads  218  so as to wipe print heads  218 . In the particular example illustrated, web  238  is also configured to contact the surfaces of print heads  218  as carriage  220  moves print heads  218  along axis  226  relative to web  238  to wipe print heads  218 . In other embodiments, web  238  may additionally be configured to be moved relative to print heads  218  to perform such wiping operations. In one embodiment, web  238  comprises a web of fluid absorbent material. In one embodiment, web  238  comprises a fabric material. According to one embodiment, web  238  is formed from a fabric material such as Evolon 100 commercially available from Freudenberg Group of Germany. 
     In one embodiment, web  238  includes non-absorbent regions  252  separating or isolating different absorbent regions  253  from one another. Non-absorbent regions  252  inhibit migration of fluid between adjacent absorbent regions  253 . Non-absorbent regions  252  inhibit migration of fluid deposited during spitting in one absorber region to other absorbent regions which are used for wiping. As a result, non-absorbent regions  252  prevent cross-contamination and increase or prolong the useful life of web  238 . 
     As shown by  FIG. 8 , web support  244  comprises one or more structures configured to support web  238  in an arc about axis  226 . In the particular example shown, web support  244  is configured to support web  238  about an arc substantially similar to the arc along which print heads  218  are arranged. In the example illustrated, web support  244  includes web guide  252  and web cover  254 . Web guide  252  comprises an elongate arcuate panel or surface underlying web  238 . In yet another embodiment, guide  252  comprises multiple individual surfaces that are spaced from one another in an arc. For example, in one embodiment, guide  252  may be formed from multiple rollers extending in the arc. 
     Web cover  254  extends over web  238  so as to sandwich and contains web  238 . As shown by  FIG. 7 , web cover  254  includes windows  256 ,  257  which expose portions of web  238 . In particular, windows  256  expose those portions of web  238  opposite to web backers  258 . In the example illustrated, web cover  252  includes three such windows  256 , wherein each window  256  exposes two web backers  258  for performing wiping operations on two of print heads  218 . 
     Windows  257  expose those portions of web  238  which are to receive fluid ejected or spit from print heads  218 . In the example illustrated, web cover  254  includes a separate window arcuately arranged about axis  226  for each of print heads  218 . In other embodiments, window  256  may comprise a continuous window through which fluid from more than one print head  218  may be ejected onto web  238 . In other embodiments, web cover  254  may have other configurations or may be omitted. 
     Web support  244  is movably coupled to frame  230  so as to move between a raised position (shown in  FIG. 7 ) for servicing print heads  218  and a retracted or lowered position (shown in  FIG. 10 ) facilitating the capping of print heads  218 . In the example illustrated, web support  244  is pivotably coupled to frame  230  at hinge  303  for pivotal movement about pivot axis  251 . In other embodiments, web support  244  may be pivotably coupled to frame  230  about other pivot axes. In still other embodiments, web support  244  may alternatively be configured to translate or slide between the raised position and the lowered position such as along one or more vertical tracks, channels or grooves. 
     Actuator  260  comprises a mechanism configured to selectively move web backer  258  between the raised and lowered positions. In one embodiment, actuator  260  may comprise one or more cams driven by a motor or other power sources. In another embodiment, actuator  260  may comprise electric solenoids, pneumatic or hydraulic cylinder assemblies or other actuation mechanisms which directly interact with web backer  258  or which drive an intermediate cam which facilitates movement of web backer  58 . In other embodiments where other mechanisms are provided for wiping of print heads  218  and where web  238  is merely used to receive fluid ejected from print heads  218 , such as during spitting or purging operations, lifters  246  may be omitted. 
     Lifters  246  comprise mechanisms configured to lift or elevate selected portions of web  238  and to press or hold such elevated portions of web  238  against opposite portions of print heads  218  to facilitate wiping of print heads  218 . In the example illustrated, each of lifters  246  includes a web backer  258  and an actuator  260 . Web backer  258  comprises a structure configured to move between (1) a raised position in which web backer  258  contacts an underside of web  238  and lifts the opposing portion of web  238  to a height sufficient to contact an associated opposing print head  218  and (2) a lowered position in which web  238  is spaced from print heads  218 . In one embodiment, in a raised position, web backer  258  supports web  238  above web support  244  and in the lowered position allows web  238  to rest upon web support  244 . 
     Actuators  260  comprise mechanisms configured to selectively move web backers  258  between the raised and lowered positions. As shown by  FIG. 8 , actuators  260  include datum  310 , lift cams  313 , cam drive motor  314  and transmission  316 . Datum  310  comprises a structure against which cams  312  are datumed (precisely positioned). In the example illustrated, datum  310  comprises a duct centered about axis  226 , the same axis about which drums  212  rotates. Because cams  212  are datumed (precisely positioned in space and with respect to other structures) directly to the rotational axis  226  of drum  212  by being directly mounted to datum  310  that locates drum axis  226 , tolerance stack may be reduced or minimized. 
     Lift cams  313  are each operably coupled to an associated web backer  258  having an associated cam follower surface  317 . Lift cams  313  are operably coupled to drive motor  314  by transmission  316 . Selective rotation of cams  313  by motor  314  raises and lowers backers  258  between the raised and lowered positions. 
     In another embodiment, actuator  260  may comprise electric solenoids, pneumatic or hydraulic cylinder assemblies or other actuation mechanisms which directly interact with web backers  258  or which drive an intermediate cam which facilitates movement of web backer  258 . In other embodiments where other mechanisms are provided for wiping of print heads  218  and where web  238  is merely used to receive fluid ejected from print heads  218 , such as during spitting or purging operations, lifters  246  may be omitted. 
       FIGS. 8-11  illustrates actuator  260  in more detail. Actuator  260  comprises a mechanism configured to move web support  244  and the supported web  38  between the raised position and the lowered position. In the raised position, web support  244  and web  238  are positioned to facilitate servicing of print heads  218 . In the lowered position, web support  244  and web  238  are sufficiently retracted from print heads  218  or lowered with respect to print heads  218  to permit insertion of caps  248  between web  238  and print heads  218 . Such raising and lowering of web support  244  permits caps  248  and web  238  to share vertical space, providing a more compact design and potentially enabling web  38  to provide it with an increased width. The increased width of web  238  increases the fluid absorption capacity of web  238  and enables service station  222  to operate for longer times without replacement of web  238 . 
     In the example illustrated, actuator  260  is configured to pivot web support  244  about axis  251  between the raised position (shown in  FIG. 10 ) and the lowered position (shown in  FIG. 11 ). In the example illustrated, actuator  260  pivots web support  244  in at least about 5 degrees such that those portions of web support  244  opposite to that print heads and closest to the pivot point of web support  244  are raised or lowered through a distance of approximately 14 mm and such at those portions of web support  244  opposite to the print heads and farthest from the pivot point of web support  244  are raised or lowered through a distance of approximately 40 mm. In other embodiments, actuator  260  may be configured to translate or slide web support  244  between the raised position and the lowered position. In other embodiments, web support  244  may be both pivoted and translated between the raised and lowered positions. 
     As shown by  FIG. 9 , in the embodiment illustrated, actuator  260  comprises datum  310 , web support lift cams  320  (also known as service station lift cams or web module lift cams), cam drive motor  314  and transmission  316 . Datum  310  comprises a structure against which cams  312  are datumed (precisely positioned). In the example illustrated, datum  310  comprises a duct centered about axis  226 , the same axis about which drums  212  rotates. Because cams  320  are located with respect to the rotational axis  226  of drum  212  by being directly mounted to datum  310  that locates drum axis  226 , tolerance stack may be reduced or minimized. 
     Cams  320  comprise cam structures configured to rotate about datum  310  and to engage corresponding cam follower surfaces  322  (shown in  FIG. 8 ) coupled to and carried by web support  244 . Cams  320  are irregularly shaped such that rotation of cams  320  against opposite associated cam followers connected to web support  244  pivot web support  244  about axis  251  to raise and lower web support  244  between the raised and lowered positions, depending upon the angular positioning of cams  320 . 
     Drive motor  314  applies torque to cams  312  via transmission  316 . In the example illustrated, transmission  316  comprises a gear train. In other embodiments, transmission  316  may comprise a chain and sprocket arrangement or a belt and pulley arrangement. Drive motor  314  rotate cams  312  to move web support  244  between the raised position and the lowered position. Because actuator  260  and actuators  260  of lifters  246  utilize a same drive motor  247 , a same transmission  316  and a same datum  310 , complexity is reduced and compactness is increased. In other embodiments, actuator  260  and actuators  260  may utilize independent motors, independent transmissions and independent datums. 
     As shown by  FIG. 7 , Caps  248  comprise structures configured to cap or seal about fluid nozzle openings of print heads  218 . Caps  248  seal about such nozzle openings when print heads  218  are not in use. Caps  248  maintain a moist environment about print heads  218  to maintain the health of the print heads  218 . In some embodiments, caps  248  may additionally be configured to provide for purging of fluid from print heads  218 . 
     In the example illustrated, caps  248  are coupled or connected to one another such a move in unison with one another. Caps  248  move between a first position at least partially withdrawn from over and above web support  244  (shown in  FIG. 7 ) and a second position over and above web support  244  to a greater extent as compared to the first position (shown in  FIG. 10 ). In the example illustrated, in the first position, caps  248  are completely withdrawn from over and above web  238 . In the second position, caps  248  project above and over web  238  by a distance of at least 25 mm and nominally about 38 mm in a direction along axis  226 . 
     As noted above, caps  248  are configured to move to the second position when web support  244  is in the lowered position. Because caps  248  share space with web support  244  and web  238 , servicing station  222  is more compact and web  238  may be provided with a greater width. As a result, the absorptive capacity of web  238  may be increased to increase the useful life of web  238 . 
     In the example illustrated, caps  48  are arranged in an arc about axis  226 . As a result, caps  248  may be more easily moved to the second position in which caps  248  are located between web  238  and print heads  218 . In other embodiments, caps  248  may have other arrangements. 
     Actuator  250  comprises a mechanism configured to move caps  48  between the first position (shown in  FIG. 12 ) and the second position (shown in  FIG. 13 ). In particular, actuator  250  moves caps  248  along axis  226  (shown in  FIG. 7 ). In one embodiment, actuator  250  is configured to additionally move caps  248  in a direction substantially perpendicular to axis  226  so as to raise caps  248  into the sealing engagement with print heads  218 . In other embodiments, separate actuators may be used to raise and lower caps  248  with respect to print heads  218 . In yet other embodiments, caps  248  may merely move along axis  226 , wherein print heads  18  are raise and lowered with respect to caps  248  for capping of print heads  218 . 
       FIGS. 12 and 13  illustrate one example of actuator  250  in detail.  FIG. 12  illustrates actuator  250  with caps  248  in the first retracted position.  FIG. 13  illustrates actuator  250  with caps  248  in the second extended position. As shown by  FIG. 12 , actuator  250  includes a slider guide  330 , slider  332 , cap links  334 , slider link  336 , arm  338 , bias  340 , carriage ram  342  and cap tab  344 . Slider guide  330  comprises one or more structures supported by frame  230  and configured to guide translation of slider  332  along axis  345 . In the example illustrated, slider guide  330  comprises one or more grooves, tracks or channels in which paper programs for not shown) extending from slider  332  is received and slides. In other embodiments, slider guide  330  may have other configurations. 
     Slider  332  (also known as a sled or carriage) comprises a member configured to slide along slider guide  330  along axis  345 . Slider  332  is pivotally connected to cap links  334  and slider link  336 . Slider  332  may have a variety of shapes and configurations. 
     Cap links  334  comprise elongate linkages extending between slider  332  and caps  248 . Cap links  334  each have a first end  346  pivotally connected to one or more of caps  248  and a second and  348  pivotally connected to slider  332 . Cap links  334  cooperate with slider  332  and caps  248  to form a four-bar linkage. This four-bar linkage facilitates vertical raising and lowering of caps  248  as will be described hereafter. 
     Slider link  336  comprises a linkage having opposite ends pivotally connected to slider  332  and arm  338 . Arm  338  comprises an elongate member pivotally coupled to frame  230  about axis  352 . Arm  338  has a first end  354  pivotally connected to link  336  and a second end  356  on an opposite side of axis  352  that is configured to being engaged and directly contacted by carriage ram  342 . 
     Bias  340  comprises one or more bias members configured to resiliently bias arm  338  towards clockwise angular rotation about pivot axis  352  as seen in  FIG. 12 . Bias  340  resiliently biases end  356  to the right as seen in  FIG. 12  and resiliently biases end  354  as well as slider  332  and caps  348  to the left as seen in  FIG. 12 . In the example illustrated, bias  340  comprises a tension spring having a first end connected to frame  230  and a second end connected to arm  338  between axis  352  and end  354 . In other embodiments, bias  340  may comprise other bias structures, such as other types of springs, at other locations. 
     Carriage ram  342  comprises a structure coupled to carriage  220  so as to move with carriage  220 . Carriage ram  342  is configured so as to engage end  356  of arm  338  to pivot arm  338  about axis  352  and a counter-clockwise direction against the bias of the bias  340 . Although illustrated as a downwardly projecting tab, carriage ram  342  may have a variety of sizes, shapes, configurations and locations. 
     Cap tab  344  comprises a protrusion or projection extending from one or more of caps  348  which are configured to be contacted, abutted or driven by carriage  220  when print heads  218  are substantially aligned over caps  248 . In the example illustrated, cap tab  344  is configured to contact and to be driven by edge  358  of the print head  218 . As shown in  FIG. 13 , when print head  218  engages and drives  344 , both ends of links  334  pivot to vertically lift or raise caps  348  into sealing engagement with print heads  218 . In other embodiments, other stop surfaces or friction clutches at the pivot point of links  334  may be utilized to cause links  334  to pivot from the tilted position shown in  FIG. 12  to the substantially vertical position shown a  FIG. 13  so as to raise caps  248 . 
     Controller  224  is similar to controller  24  (shown in  FIG. 1 ). Controller  224  comprises one or more processing units configured to generate control signals directing the operation of printing system  210 . Comptroller  224  may be associated with printer  210  or in some embodiments, maybe associated with a peripheral computing device connected to printer  210 . Controller  224  generates control signals directing the positioning of media by media supply  214  and rotation of drum  212  by rotary actuator  213 , directing the positioning of print heads  218  through movement of carriage  220  by actuator  221 , directing the ejection of fluid by print heads  18 , and directing the servicing of print heads  218  at service station  222 . 
     With respect to service station  222 , controller  224  tracks operation web drive  236  to control the supply of web  238 . Controller  224  generates control signals directing operation of actuators  260  and  260  to provide spitting, wiping and capping servicing operations. Controller  224  also generates control signals directing operation of actuator  250 . In the embodiment illustrated in which actuator  250  transmits motion or force received from movement of carriage  220  to caps  248 , controller  224  controls positioning of caps  248  through its control of actuator  221  which moves carriage  220 . Controller  224  is coupled to rotary actuator  213 , media supply  214 , print heads  218 , actuator  221 , web drive  236 , actuators  260  and actuator  250  (where applicable) in a wired fashion or in a wireless fashion. 
     In contrast to  FIG. 7 , which illustrates web support  244  and web  238  in the raised position and illustrates caps  248  in the first retracted position,  FIG. 14  illustrates web support  244  and web  238  in the lowered position and illustrates caps  248  in the second extended position at least partially over web  238 . To achieve this state, controller  224  generates control signals directing motor  314  to rotate cams  322  lower web support  244  and web  238  from the raised position shown in  FIG. 10  to the lowered position shown in  FIG. 11 . Controller  224  further generates control signals directing actuator  221  to drive and translate carriage  220  from the first position shown in  FIG. 12  is to the capping position shown  FIG. 13 . During this translation of carriage  220 , carriage ram  342  first contacts end  356  of arm  338 . Continued movement of carriage  220  to the left (as seen in  FIG. 12 ) pivots arm  338  about axis  352  to drive slider  332  to the right as seen in  FIG. 12 . Movement of slider  332  to the right results in caps  248  also being moved to the right as seen in  FIG. 12  from the first position to the second position in which caps  248  least partially overlie web  238 . During such translation to the right, links  334  are in the orientation shown in  FIG. 12 . Upon caps  248  and print heads  218  moving into alignment with one another (caps  248  moving to the right and print heads  218  moving to the left as seen in  FIG. 13 ) edge  358  of print heads  218  contacts tab  344 . As a result, slider  248  moves to the right relative to caps  248  so as to pivot links  334  in a counter-clockwise direction as seen in  FIG. 13 . This results in caps  248  being vertically lifted into closer sealing engagement with print heads  218 . Because caps  248  move in a substantially horizontal path followed by a substantially vertical path, horizontal translation of caps  248  while in contact with printed several  218  is reduced or eliminated. As a result, a better sealing alignment is achieved with reduced wear to either print heads  218  or caps  248 . As noted above, because caps  248  share space with the underlying web  238  and web support  244 , service station  222  is more compact and a width of web  238  may be increased for greater absorptive and wiping capacity. 
     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.