Patent Publication Number: US-8534794-B1

Title: Ink recirculation system having a porous pad

Description:
TECHNICAL FIELD 
     This disclosure relates generally to systems that supply and recover fluid from a device, and more particularly, to an inkjet printer configured to recover liquid ink from an inkjet printhead. 
     BACKGROUND 
     Fluid transport systems are well known and used in a number of applications. One specific application of transporting a fluid in a machine is the transportation of ink in a printer. Common examples of inks include aqueous inks and phase change or solid inks. Aqueous inks remain in a liquid form when stored prior to being used in imaging operations. Solid ink or phase change inks typically have a solid form, such as pellets or as ink sticks, which are inserted into feed channels in a printer through openings to the channels. After the ink sticks are fed into the printer, the ink sticks are urged by gravity or a mechanical actuator to a heater assembly of the printer. The heater assembly includes a heater positioned proximate to a melt plate to heat the melt plate to a temperature that melts an ink stick contacting the melt plate. The melt plate can be oriented to drip melted ink into a reservoir and the ink stored in the reservoir continues to be heated until the ink is fed to an inkjet ejector. 
     Fluid couplings in the printer supply the liquid ink held in each reservoir of colored ink to one or more printheads in the inkjet printing apparatus. The liquid ink is pumped from the reservoir to a manifold in the inkjet printing apparatus. As the inkjets in the printheads eject ink onto an image receiving member, the action of the diaphragms in the inkjets pulls ink from the manifold. Various embodiments of inkjets include piezoelectric and thermal devices that are selectively activated electrical firing signals received from a controller. 
     Phase change ink printers often include one or more heaters that generate heat to maintain a supply of phase change ink in a liquid state in the printheads and inkjets for use during printing operations. Typically, the heaters are electrical heaters that consume electrical energy to generate the desired amount of heat. In order to reduce energy usage, phase change ink printers deactivate various components, including heaters, in the printer during a sleep mode to conserve energy. The ink held in the printheads and inkjets cools and solidifies when the heaters are deactivated. 
     While sleep modes enable a printer to operate with reduced electrical energy consumption, the solidification of phase change ink within the printer presents difficulties in printing high quality documents when the printer emerges from sleep mode. As phase change ink within an inkjet printing apparatus cools and solidifies, the ink contracts, allowing air into the pressure chambers and fluid conduits within the printheads. As the solidified ink heats and liquefies during a subsequent warm-up process, the air forms bubbles in the liquefied ink that can interfere with operation of the inkjets in the printhead. Additionally, during the warm-up process, both the ink and air bubbles expand due to the heat applied to the printheads. The expanding air bubbles may force some ink through the ejector nozzles, which is referred to as “drooling.” The drooled ink can contaminate other nozzles in the printheads or separate from the printheads and produce errant marks on the image receiving member. 
     To eliminate air bubbles in the liquefied ink within the printheads and to clear contaminants from the inkjet nozzles and external face of each printhead, the inkjet printing apparatus undergoes a “purge” operation, during which pressure applied to the printheads urges the liquid ink and the air bubbles through the nozzles of the inkjets. In a purge operation, the inkjets emit a stream of ink that flows down the face of the printhead and is collected in a waste ink receptacle. The purge operation removes air bubbles from the inkjets in the printheads and other fluid conduits in the inkjet printing apparatus. 
     In some printing apparatus designs, a wiping operation occurs after the purge operation. In a wiping operation, a wiper blade engages the face of a printhead and moves across the printhead face. The wiper blade cleans residual ink and contaminants that remain on the face of the printhead after the purge operation. In existing printers, the purged ink and ink from a wiping operation is typically collected in a waste reservoir and is eventually discarded. In printers that enter sleep modes more often to reduce electrical energy consumption, the number of purge cycles and the corresponding amount of discarded ink increases. Thus, improvements to phase change ink printers that reduce or eliminate discarded ink produced during purge cycles are desirable. 
     SUMMARY 
     In one embodiment, a device for cleaning a printhead and collecting the ink from the printhead for recycling or disposal has been developed. The device includes a porous pad, a support member, a heated member, and a first actuator. The porous pad is fixedly attached to the support member, and the first actuator is operatively connected to the support member. The first actuator is configured to move the support member to a first position where the porous pad is proximate to a face of a printhead to enable the porous pad to absorb melted phase change ink from the face of the printhead by capillary action, and to a second position where the porous pad is pressed against the heated member to enable the heated member to release ink from the porous pad to enable the released ink to be directed to an ink receptacle. 
     In another embodiment, a method of operating a printer collects ink purged from an inkjet printhead for recycling or disposal. The method includes moving a porous pad to a first position to absorb melted phase change ink from a face of a printhead by capillary action, the porous pad being fixedly attached to a support member that is operatively connected to a first actuator to enable the first actuator to move the porous pad to the first position. The method further includes moving the porous pad to a second position, where the porous pad is pressed against a heated member to enable the heated member to release ink from the porous pad and to enable the released ink to be directed into an ink receptacle. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of an ink collecting assembly. 
         FIG. 2  is side view of the ink collecting assembly of  FIG. 1  absorbing ink from a printhead face. 
         FIG. 3  is a side view of the ink collecting assembly of  FIG. 1  engaged with a heated plate. 
         FIG. 4  is a side view of the ink collecting assembly of  FIG. 1  engaged with a drip bib. 
         FIG. 5  is a side view of another ink collecting assembly absorbing ink from a printhead face. 
         FIG. 6  is a side view of the ink collecting assembly of  FIG. 5  engaged with a plurality of heated plates. 
         FIG. 7  is a perspective view of the ink collecting assembly of  FIG. 5  with the heated plates removed for clarity. 
         FIG. 8  is a side view of another embodiment of an ink collecting assembly engaged with a printhead during a purge cycle. 
         FIG. 9  is a side view of the ink collecting assembly of  FIG. 8  engaged with a drip bib. 
     
    
    
     DETAILED DESCRIPTION 
     For a general understanding of the environment for the system and method disclosed herein as well as the details for the system and method, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate like elements. As used herein, a “purge” refers to a maintenance procedure performed by an inkjet printing apparatus to forcibly expel ink from the inkjet ejectors in one or more printheads in an effort to clear the inkjet ejectors. A purge can be performed by applying air pressure to an ink reservoir that is fluidly coupled to the inkjets in the printheads or by applying suction to the inkjet nozzles. A purge is typically used to remove air bubbles from conduits within the printheads or other sections of a fluid path in the inkjet printing apparatus that form each time phase change ink is melted from solid to liquid. A purge can also be performed to clear contaminants from inkjet ejectors. The term “purged ink” refers to ink expelled during a purge operation. The purged ink flows down the face of the printhead instead of being ejected toward an image receiving surface. As used herein, the terms “solid ink” and “phase change ink” both refer to inks that are substantially solid at room temperature and substantially liquid when heated to a phase change ink melting temperature for ejection from an inkjet ejector. The phase change ink melting temperature can be any temperature that is capable of melting solid phase change ink into liquid or molten form. 
     As used herein, the term “face” in the context of a printhead refers to a substantially planar region of a printhead that includes a plurality of inkjet nozzles. The printhead ejects ink drops through the apertures in a face plate, sometimes called “nozzles,” of the printhead onto an image receiving surface during a printing operation. During a purge operation, pressure is used to eject ink through the nozzles and onto the face of the printhead. 
       FIG. 1  depicts an ink collecting assembly  100 . The ink collecting assembly  100  includes a horizontal actuator  160 , a vertical actuator  164 , a support member  120 , a porous pad  104 , a heated plate  180 , and a controller  198 . The horizontal actuator  160  includes an output shaft  162 , which is operatively connected to and configured to move the support member  120  in the horizontal direction to enable the porous pad  104  to move into engagement with a face  204  of a printhead  200  or to contact a heated plate  180  or a drip bib  264 . The vertical actuator  164  includes an output shaft  166 , which is operatively connected to a belt  168  that is attached to the horizontal actuator  160 . As the vertical actuator  164  operates, the output shaft  166  rotates, moving the belt  168 . The horizontal actuator  160 , the support member  120 , and the porous pad  104  move vertically in response to the belt  168  moving to enable the pad to contact different portions of the printhead face  204 , the drip bib  264 , and the heated plate  180 . The horizontal  160  and vertical  164  actuators can be electric stepper motors, pneumatic actuators, or any other actuator capable of moving the ink collecting assembly  100 . Although the embodiment of  FIG. 1-4  uses horizontal and vertical actuators to move the ink collecting assembly, the reader should appreciate that any suitable actuation system can be used to move the ink collecting assembly to contact the printhead face, the heated plate, and the drip bib, and that the actuators need not be oriented vertically and horizontally. 
     Operation and control of the horizontal  160  and vertical  164  actuators of the ink collecting assembly  100  are performed with the aid of the controller  198 . The controller  198  is operatively connected to the actuators  160  and  164  and is configured to generate electrical signals that activate and deactivate the actuators  160  and  164 . The controller  198  can be integrated with a controller that operates the printhead  200 , heater  176 , and other components of the printer, or the controller  198  can be a separate controller that operates only the actuators  160  and  164 . The controller can be implemented with general or specialized programmable processors that execute programmed instructions. The instructions and data required to perform the programmed functions are stored in memory associated with the processors or controllers. The processors, their memories, and interface circuitry configure the controller to perform the functions described below. These components can be provided on a printed circuit card or provided as a circuit in an application specific integrated circuit (ASIC). Each of the circuits can be implemented with a separate processor or multiple circuits can be implemented on the same processor. 
     The porous pad  104  is fixedly attached to the support member  120  and is configured to absorb ink from the printhead face  204  as the ink is purged from the inkjets in the face  204 . Other embodiments can include more than one porous pad to enable collection of ink of different colors from the printhead face separately or to enable the ink collecting assembly to absorb greater quantities of ink. The porous pad  104  can be formed of any material suitable for wicking phase change ink from the printhead face  204 , for example, a filter, cloth, or sponge material, which can be firm or flexible, is suitable for use as a pad. The pad  104  is configured to absorb at least an amount of ink ejected by the printer during a purge operation. In one embodiment the pad  104  is configured to absorb an amount of ink corresponding to at least three purge operations. In another particular embodiment, the pad is configured to absorb approximately ten grams of ink. To melt the ink absorbed in the porous pad for removal, the porous pad  104  can include an attached heater to generate thermal heat, or the pad can be heated by contact with the printhead, drip bib, and heated plate. 
     In operation, the controller  198  operates the vertical actuator  166  to move the ink collecting assembly  100  to position the porous pad  104  opposite the printhead face  204  as the printhead  200  prepares for a purge operation. The controller  198  activates the horizontal actuator  160  to move the support member  120  and porous pad  104  into contact with the printhead face  204 , as shown in  FIG. 2 . The pad  104  remains in contact with the printhead face  204  as the inkjets in the printhead  204  begin purging ink. In a multi-color printhead, the inkjets in the printhead face eject ink of multiple colors, which combine to form an approximate black ink  260 . The approximate black ink  260  soaks into the porous pad  104 , where the ink  260  cools and solidifies. In another embodiment, the printhead ejects only one color of ink, which is absorbed by the pad for recycling or disposal. The horizontal actuator can be configured to compress the pad into the printhead face before the ink is purged. As the compressed pad is moved away from the printhead face, the decompression of the pad pulls the absorbed ink deeper into the pad, enabling the pad to absorb a larger quantity of ink from the printhead face. 
     The controller  198  can be further configured to operate the vertical actuator  164  to move the ink collecting assembly  100  downwardly while the porous pad  104  is in contact with the printhead face  204  to wipe the printhead face. When the porous pad  104  is moved downwardly, ink  260  remaining on the printhead face is absorbed into the pad  104  or urged downwardly onto the drip bib  264  and into the ink receptacle  268 . The ink collecting assembly  100  also includes a urethane wiper  172  configured to wipe the printhead face. In the illustrated embodiment the wiper  172  is mounted on the support member  120  above the porous pad  104  and configured to wipe the printhead as the porous pad  104  wipes downwardly on the printhead face  204 . The wiper  172  is attached to the support member  120  by a biasing member, for example a spring, to enable the wiper to extend beyond the porous pad  104  to enable the wiper  172  to wipe the printhead face  204  while the porous pad  104  is not in contact with the face  204 . When the porous pad  104  is moved into contact with the face  204 , the biasing member deforms to prevent the wiper from interfering with the operation of the porous pad  104 . Alternatively, the wiper can be fixedly mounted to the support member and configured to wipe the printhead face only when the porous pad contacts the printhead face. 
     After the purge operation is complete, the controller  198  operates the horizontal actuator  160  to move the ink collecting assembly  100  out of contact with the printhead face  204 . The controller  198  operating the ink collecting assembly  100  can be configured to wait for the next purge cycle, recycle the ink absorbed in the pad  104  back into the printhead  200 , or deposit the absorbed ink  260  into the ink receptacle  268 . The controller  198  of the ink collecting assembly can also be configured to recycle some or all of the ink in the pad  104  after a predetermined number of purge cycles, and to deposit the absorbed ink into the ink receptacle  268  after a second predetermined number of purge cycles. 
       FIG. 3  illustrates the ink collecting assembly  100  positioned to recycle the ink  260  absorbed in the porous pad  104 . To recycle the ink  260  absorbed in the porous pad  104 , the controller  198  operates the vertical actuator  164  to rotate the output shaft  166 , which moves the belt  168  and the ink collecting assembly  100  upwardly to position the porous pad  104  opposite the heated plate  180 . The horizontal actuator  160  then activates to press the porous pad  104  into the heated plate  180 . A heater  176  operatively connected to the heated plate  180  generates thermal heat, which heats the plate  180  and the pad  104  when the pad  104  contacts the plate  180 . As the pad  104  is pressed into the heated plate  180 , heat from the plate  180  melts some or all of the ink in the porous pad  104 , enabling the melted ink to flow down the heated plate  180 . The heated plate  180  is configured to direct the approximate black ink  260  into a reservoir  236  in the printhead  200  containing black ink. The pressure and heat applied to the porous pad  104  controls the amount of ink released from the pad  104  to flow into the black ink reservoir. In one embodiment, the porous pad  104  is configured to recycle about one gram to about two grams of approximate black ink  260  in a single recycle operation to avoid compromising the black ink quality with combined ink. 
     After a second predetermined number of purge cycles, the controller  198  is configured to release the ink stored in the pad  104  into the ink receptacle  268 . The controller  198  operates the vertical actuator  164  to move the ink collecting assembly  100  downwardly until the porous pad  104  is positioned opposite the drip bib  264 , which is mounted to the bottom of the printhead  200 . The controller  198  then operates the horizontal actuator  160  to move the pad  104  into contact with the drip bib  264  as demonstrated by the position shown in  FIG. 4 , compressing the pad  104  against the drip bib  264 . The drip bib  264  can include a heater to melt the phase change ink in the pad, or the drip bib  264  can be heated above the melting temperature of the phase change ink by the printhead  200 . As the pad  104  presses into the drip bib  264 , the heat from the drip bib  264  heats the pad  104 , melting the approximate black ink  260  stored in the porous pad  104 . The melted ink is released from the pad and flows down the drip bib  264  into the ink receptacle  268 . After being collected in the ink receptacle  268 , the approximate black ink  260  can be disposed of or recycled. The compression of the porous pad  104  against the drip bib  264  again controls the amount of ink released from the porous pad  104 . In one embodiment, the amount of ink released from the porous pad is configured to be greater than one gram to avoid small amounts of phase change ink dripping into the ink receptacle and solidifying to form “stalagmites” in the ink receptacle, preventing the ink from filling the ink receptacle uniformly. 
       FIG. 5  depicts another ink collecting assembly  300 . The ink collecting assembly  300  includes an actuator  360 , four support members  324 ,  328 ,  332 , and  336 , four porous pads  304 ,  308 ,  312 , and  316 , four ink channels  344 ,  348 ,  352 , and  356  ( FIG. 7 ), four heated plates  384 ,  388 ,  392 , and  396  ( FIG. 6 ), and a controller  398 . The porous pads  304 ,  308 ,  312 , and  316  are mounted to support members  324 ,  328 ,  332 , and  336 , respectively. As above, the porous pads  304 - 316  are formed of a material that enables the pads  304 - 316  to absorb ink from the printhead face  204  by capillary action. The support members  324 - 336  are operatively connected to a heater  372 , which is configured to heat the support members  324 - 336  and porous pads  304 - 316  to a temperature suitable to liquefy phase change ink stored therein. The controller  398  is operatively connected to the actuator  360 , and is configured similar to the controller described above with reference to  FIG. 1-4 . 
     The heated plates can be formed of any suitable material, such as anodized aluminum. In some embodiments, the heated plates are coated with a hydrophobic agent to prevent ink from adhering to the surface of the heated plates. The heated plates  384 - 396  are substantially the same size as the porous pads  304 - 316  to enable each heated plate  384 - 396  to contact only one porous pad  304 - 316 . The heated plates are each heated by a heater  376 , and can be mounted to the printhead or to any suitable structure in the printer. In other embodiments, the heated plates can be heated by a single heater. In one embodiment the heaters are an electrical resistive heater formed from nichrome wire, although in other embodiments other heaters are used. 
     The actuator  360  includes an output shaft  362  operatively connected to a belt  368 . The actuator  360  is configured to rotate the output shaft  362 , which moves the belt  368 . The belt  368  is operatively connected to the support members  324 - 336 , and moves the support members  324 - 336  in response to the output shaft  362  rotating. Although a belt drive is illustrated in the embodiment of  FIG. 5-FIG .  7 , any suitable drive mechanism can be used to move the ink collecting assembly  300 , for example a gear drive, a friction drive, or a combination of drive components. 
     The actuator  360  moves the ink collecting assembly  300  to enable the porous pads  304 - 316  to contact the face  204  of the printhead  200 . In the embodiment of  FIG. 5 , the printhead  200  is rotated about pivot point  272  by an actuator (not shown) or other suitable mechanism. The printhead  200  pivots in direction  276  ( FIG. 5 ) to enable the pads  304 - 316  to contact the printhead face  204 , and pivots in direction  280  ( FIG. 6 ) to enable the ink collecting assembly  300  to pass by the printhead  200  without interference. As shown in  FIG. 7 , the printhead  200  includes four ink reservoirs  224 ,  228 ,  232 , and  236 , to enable the printhead  200  to accept each color of ink printed separately. In the embodiment of  FIG. 5 , the printhead  200  is configured with four groups of inkjet nozzles, each group being arranged substantially in a line and configured to eject a single color of ink. 
     In operation, one or more controllers operate a printer in which the ink collecting assembly  300  is installed periodically initiates a purge cycle in response to a user input, a predetermined number of print cycles, or during printer warm-up. The actuator  360  rotates, rotating the output shaft  362 , which moves the belt  368  and the ink collecting assembly  300 . The printhead  200  is configured to pivot in direction  276  about pivot point  272  to enable the porous pads  304 - 316  to contact the printhead face  204  and optionally to exert pressure on the porous pads  304 - 316  to compress the pads  304 - 316  into the printhead face  204 . The actuator  360  rotates to position the ink collecting assembly to contact the printhead face  204  with the pads  304 - 316 . The printhead  200  initiates a purge operation, pressurizing ink reservoirs within the printhead and causing ink to flow out of the inkjets in the printhead face  204 . The porous pads  304 - 316  are in contact with the printhead face to absorb the purged ink as the ink flows out of the inkjets. Each pad  304 - 316  is aligned with one group of inkjets, and is substantially the same size as the inkjet group to enable each pad  304 - 316  to absorb a single color of ink from the printhead face during a purge operation. For example, cyan ink  244  flows from the upper inkjet group into the cyan pad  304 , magenta ink  248  flows from the second inkjet group into the magenta pad  308 , yellow ink  252  flows into the yellow pad  312  from the third inkjet group, and black ink  256  flows into the black pad  316  from the fourth inkjet group. 
     Referring now to  FIG. 6 , after the pads  304 - 316  have absorbed the purged ink  244 - 256 , a controller  398  activates the actuator  360  to rotate the output shaft  362  and move the belt  368 . In response, the ink collecting assembly  300  moves upwardly along the belt path to a position above the printhead. The printhead is pivoted in direction  280  about pivot point  272  to enable the ink collecting assembly  300  to pass by the printhead  200  without contacting the printhead face  204  and to position the printhead  200  to receive the ink  244 - 256  from the pads  304 - 316 . As the ink collecting assembly  300  reaches the heated plates, the actuator  360  continues to operate, pulling the ink collecting assembly  300  into contact with the heated plates  384 - 396 . The ink collecting assembly  300  pivots in response to the continued operation of the actuator  360  to enable the porous pads  304 ,  308 ,  312 , and  316  to contact heated plates  384 ,  388 ,  392 , and  396 , respectively. The heaters  376  on each of the heated plates  384 - 396  are activated to heat the porous pads and melt the phase change ink in the pads  304 - 316 . As the porous pads  304 ,  308 ,  312 , and  316  are pressed into heated plates  384 ,  388 ,  392 , and  396 , the ink  244 ,  248 ,  252 , and  256  in the porous pads is forced into a chamber (not shown) in each of the support members  324 ,  328 ,  332 , and  336 , respectively. 
       FIG. 7  is a perspective view of the ink collecting assembly  300  and printhead  200  of  FIG. 6  with the heated plates and heaters removed to better show the ink collecting assembly  300 . Porous pads  304 ,  308 ,  312 , and  316  are fluidly connected to chambers (not shown) within the support members  324 ,  328 ,  332 , and  336  by one or more apertures (not shown) in the support members  324 ,  328 ,  332 , and  336  behind the porous pads  304 ,  308 ,  312 , and  316 , respectively. The chambers in the support members  324 ,  328 ,  332 , and  336  are fluidly connected to ink channels  344 ,  348 ,  352 , and  356 , respectively, through ink conduits within the support members. Thus, as the porous pads  304 - 316  are pressed against the heated plates  384 - 396  the ink in the pads is released into the chambers within the support members  324 - 336 . Heater  372  keeps the ink within the chambers in a liquid form as the ink is directed to the ink channels  344 - 356 . Black ink is directed from support member  336  to channel  356 , where the black ink flows into the black ink reservoir  236  in the printhead  200 . Cyan, yellow, and magenta inks are directed from support members  324 ,  328 , and  332 , respectively, into channels  344 ,  348 , and  352 , where the ink flows into cyan  224 , magenta  228 , and yellow  232  ink reservoirs, respectively. Once the ink is directed into the appropriate reservoir, the ink is mixed with the ink of the corresponding color in the printhead  200  for ejection by the inkjet nozzles onto an image receiving surface or in another purge cycle. 
       FIG. 8  depicts another ink collecting assembly  400 . The ink collecting assembly  400  includes a horizontal actuator  160 , a vertical actuator  164 , a support member  420 , a porous pad  404 , and a controller  498 . The horizontal  160  and vertical  164  actuators, including output shafts  162  and  166  and belt  168 , operate in the same manner as the actuators described above with reference to  FIG. 1-4  to move the support member  420  and porous pad  404 . The porous pad  404  is affixed to the support member  420 , which is attached to an output shaft  162  of the horizontal actuator  160  to enable the support member  420  and porous pad  404  to move in response to the output shaft  162  moving. The controller  498  is operatively connected to the actuators  160  and  164  and is configured similar to the controller described above with reference to  FIG. 1-4 . 
     The porous pad  404  includes an upper portion  408 , a lower portion  412 , and a recessed portion  416 . The upper portion  408  and lower portion  412  are separated by the recessed portion  416 , which defines a void  418  between the recessed portion  416  and the printhead face  204  when the top  408  and bottom  412  portions are in contact with the printhead face  204 . 
     In operation, the controller  498  operates the vertical actuator  164  to move the ink collecting assembly  400  opposite the printhead  200  in response to the printhead  200  initiating a purge operation. The controller  498  operates the horizontal actuator  160  to push the support member  420  and porous pad  404  into contact with the printhead face  204 . The porous pad  404  can optionally be compressed into the printhead face  204  to enable the pad  404  to absorb ink deeper into the pad  404 . While the porous pad  404  is in contact with the printhead face  204 , ink begins purging through the inkjet nozzles. Ink pours from the nozzles and flows down the printhead face  204  within the void  418  between the upper  408  and lower  412  portions of the porous pad  404 . The ink flows downwardly until the ink  260  is absorbed by the lower portion  412  of the porous pad  404 . 
     After the purge is complete, residual ink may remain on the printhead face  204 . To remove the residual ink, the controller  498  operates the vertical actuator  164  to move the support member  420  and porous pad  404  downwardly while the pad  404  remains in contact with the printhead face  204 . As the porous pad  404  moves downwardly, the upper portion  408  of the pad  404  wipes the printhead face  204 , absorbing any ink remaining on the face  204 . The vertical actuator  164  continues moving the support member  420  and porous pad  404  downwardly until the upper portion  408  of the porous pad contacts the drip bib  264  in the position shown in  FIG. 9 . 
     Once the porous pad is in the position of  FIG. 9 , the controller  498  operates the horizontal actuator  160  to compress the porous pad  404  into the drip bib  264 . In response, the ink  260  in the lower portion  412  of the pad  404  is released from the pad, and the ink  260  flows down the drip bib  264  and into the ink receptacle  268 . The ink  260  in the upper portion  408  of the pad  404  flows down the drip bib  264  and soaks into the lower portion  412  of the pad  404 . The horizontal actuator  160  is then operated to disengage the porous pad  404  from the drip bib, and then to compress the pad  404  against the drip bib again to release additional ink from the pad  404 . The controller  498  can be configured to operate the horizontal actuator  160  to repeatedly disengage and reengage the pad  404  with the drib bib  264  a predetermined number of times to release a greater quantity of the ink stored in the pad. 
     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.