Patent Publication Number: US-8529015-B2

Title: Apparatus and method for removal of ink from an exterior of a printhead

Description:
TECHNICAL FIELD 
     This disclosure relates generally to imaging devices that eject ink to form images on print media, and, more particularly, to devices that clean ink from printheads in such printers. 
     BACKGROUND 
     In general, inkjet printing machines or printers include at least one printhead that ejects drops or jets of liquid ink onto recording media or onto an image receiving member surface. A phase-change inkjet printer employs phase-change inks that are in the solid phase at ambient temperature, but transition to a liquid phase at an elevated temperature. A mounted printhead ejects drops of the molten ink to form an ink image. The ink can be ejected directly onto print media or onto an image receiving member surface, such as a rotating drum or moving belt, before the image is transferred to print media. Once the ejected ink is transferred to the print medium the ink droplets quickly solidify to form an image. 
     The media used in both direct and offset printers are typically provided in sheet or web form. A media sheet printer typically includes a supply drawer that houses a stack of media sheets. A feeder removes a sheet of media from the supply and directs the sheet along a feed path past a printhead so the printhead ejects ink directly onto the sheet. In offset sheet printers, a media sheet travels along the feed path to a nip formed between the rotating imaging member and a transfix roller. The pressure and heat in the nip transfer the ink image from the imaging member to the media. In a web printer, a continuous supply of media, typically provided in a media roll, is entrained onto rollers that are driven by motors. The motors and rollers pull the web from the supply roll through the printer to a take-up roll. As the media web passes through a print zone opposite the printhead or heads of the printer, the printheads eject ink onto the web. Along the feed path, tension bars or other rollers remove slack from the web so the web remains taut without breaking. 
     Printers can conduct various maintenance operations to ensure that the ink ejectors in each printhead operate efficiently. A cleaning operation is one such maintenance operation. The cleaning process removes particles or other contaminants that interfere with printing operations from the printhead, and unclogs solidified ink or contaminants from inkjet ejectors. During a cleaning operation, the printheads purge ink through some or all of the ink ejectors in the printhead. The purged ink flows through the ejectors and down the front face of the printheads, where the ink drips into an ink receptacle. To control the flow of ink down the face of each printhead, some printhead assemblies include a drip bib positioned below each printhead. The drip bib has a shape that directs liquid ink toward the ink receptacle. The lower edge of the drip bib tapers to one or more channels or points where ink collects prior to dripping into the receptacle. In some printers, a wiper engages the front face of the printhead and wipes excess purged ink in a downward direction toward the drip bib to remove excess purged ink. 
     While existing cleaning processes are useful to maintain printheads, removing residual purged ink from the drip bib presents a challenge. Due to surface tension, a small portion of the purged ink that flows down the drip bib remains in contact with the drip bib after the cleaning process. Existing drip bibs include a coating of a low surface energy material, such as polytetrafluoroethylene, to reduce the adhesion between the ink and the drip bib, but small amounts of ink remain on the drip bib after the cleaning process is completed. In inkjet printers using a phase-change ink, this residual ink may cool and solidify while on the drip bib. Occasionally, the solidified ink breaks free from the drip bib and interferes with imaging operations. When the solidified ink separates from the drip bib, the ink may contact the web as the web moves past printheads in the print zone. The solidified ink may negatively affect image quality on the web, and the web may carry the solidified ink past one or more printheads in the print zone. Since printheads are often positioned a short distance from the web, the carried ink may contact the face of one or more printheads with adverse consequences. Thus, improved printhead cleaning is desirable. 
     SUMMARY 
     In one embodiment, a method for cleaning ink from a printhead in a printer has been developed. The method includes activating a heater to heat a drip bib positioned below a plurality of inkjets in the printhead to a first temperature that enables phase-change ink on a surface of the drip bib to melt, and emitting pressurized air toward the surface of the drip bib from a pressurized air source to remove the melted phase-change ink from the surface of the drip bib. 
     In another embodiment, an inkjet printing apparatus has been developed. The apparatus includes a printhead including a plurality of inkjets arranged in a face of the printhead and a drip bib positioned below the face of the printhead, a heater operatively connected to the printhead, a pressurized air source configured to emit pressurized air, and a controller operatively connected to the heater and the pressurized air source. The controller is configured to activate the heater to heat the drip bib to a first temperature to enable phase-change ink on a surface of the drip bib to melt, and activate the pressurized air source to emit the pressurized air toward the surface of the drip bib to remove the melted phase-change ink from the surface of the drip bib. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a printhead maintenance unit that includes a pressurized air outlet. 
         FIG. 2  is a front view of the printhead maintenance unit of  FIG. 1  with the pressurized air outlet positioned to direct pressurized air toward a drip bib in a printhead. 
         FIG. 3  is a perspective view of a printhead array and array of printhead maintenance units. 
         FIG. 4  is a block diagram of a process for removing ink from an exterior of a printhead. 
         FIG. 5  is a perspective view of a prior art printhead that includes 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 the term “printer” refers to any device that is configured to form ink images on media and includes photocopiers, facsimile machines, multifunction devices, as well as direct and indirect inkjet printers. An image receiving surface refers to any surface that receives ink drops, such as an imaging drum, imaging belt, or various print media including paper. 
       FIG. 5  depicts a prior art printhead  500 . The printhead  500  includes a printhead housing  504 , a printhead face  508 , and a drip bib  512 . The printhead housing  504  includes an ink manifold that supplies liquefied ink to an array of inkjets. Each inkjet ejects ink drops through an aperture, or nozzle, and the printhead  500  includes an array of inkjet nozzles  510  formed in a two-dimensional arrangement in a printhead face  508 . During an imaging operation, the inkjets eject drops of ink through the nozzles  510  and onto an image receiving surface, such as a media web or sheet of paper, or onto an indirect image receiving member, such as an imaging drum or belt. 
     The printhead  500  includes a heater  530 , depicted schematically in  FIG. 5 , which generates heat to melt phase-change ink in the printhead for printing and purging operations. The heater  530  heats both the printhead  500 , including internal ink manifolds, the printhead face  508 , inkjets  510 , and the drip bib  512 . In the embodiment of  FIG. 5 , the heater  530  is an electrical heater that can include one or more heating elements positioned in the printhead  500 . 
     The drip bib  512  is positioned below the printhead face  508  with a top edge  514  of the drip bib abutting the bottom of the printhead face  508 . Fasteners  520 A and  520 B secure the drip bib  512  to the printhead  500 . In the embodiment of  FIG. 5 , the fasteners  520 A and  520 B are bolts that pass through the drip bib  512  and engage threaded holes (not shown) formed in the printhead  500 . The bottom edge of the drip bib  512  is formed with a plurality of downward pointed tips  516 A- 516 D. Ink flows toward the downward pointed tips  516 A- 516 D and drips from the drip bib into an ink collection receptacle. Alternative drip bib embodiments have different configurations of the lower edge including flat lower edges that converge to a different number of tips and drip bibs that include fluid channels to direct liquid ink to one or more outlets along the lower edge of the drip bib. In the embodiment of  FIG. 5 , polytetrafluoroethylene or another low surface energy material that resists adhesion between the purged ink and the surface of the drip bib coasts the drip bib  512 . 
     During a printhead maintenance operation in the printhead  500 , air pressure applied to the ink manifold in the housing  504  purges ink through the inkjet nozzles  510  in a stream instead of as individual drops. The purged ink flows down the printhead face in direction  540  and onto the surface of the drip bib  512 . The majority of the purged ink flows toward the downward pointed tips  516 A- 516 D and subsequently leaves the drip bib  512 . Some of the purged ink, however, remains in contact with the drip bib  512  as residual ink on the face of the drip bib  512 , near the downward pointed tips  516 A- 516 D, and on the fasteners  520 A- 520 B. As described in more detail below, a printhead maintenance system using pressurized air removes the residual ink from the drip bib  512  during the printhead maintenance process. 
       FIG. 1  depicts a printhead maintenance unit  100  that includes a pressurized air emitter  104  and a wiper assembly  132 . The pressurized air emitter  104  includes an outlet housing  106  that forms an outlet  108 , a pressurized air source  112 , air conduit  116 , and valve  118 . The outlet housing  106  is located below the wiper assembler  132  and is formed with a downward curved shape to orient the outlet  108  at a downward angle with respect to a printhead. As depicted in more detail below, the outlet housing  106  and outlet  108  direct pressurized air toward a drip bib that is positioned below an array of inkjet nozzles formed in a face of a printhead. The outlet housing  106  and outlet  108  direct pressurized air onto the drip bib and away from inkjets in the printhead to avoid formation of air bubbles within the printhead due to a flow of pressurized air through the inkjet nozzles. Additionally, the downward angle of the pressurized air outlet  108  urges ink formed on the surface of the drip bib into an ink receptacle for collection during the maintenance process. The outlet housing  106  and outlet  108  have a width that corresponds to a width of a drip bib. The elongated configuration of the outlet  108  emits pressurized air in a linear configuration across the width of the drip bib. The pressurized air emitter  104  is alternatively referred to as an “air knife” since the outlet  108  emits the pressurized air in a linear area that is similar to the edge of a knife. 
     In the embodiment of  FIG. 1 , printhead maintenance unit  100  houses the pressurized air source  112 , which is depicted schematically as an electrically powered air compressor. The pressurized air source  112  generates pressurized air and directs the pressurized air through an air conduit  116  to the outlet  108 . In other embodiments, the pressurized air source  112  is housed externally from the printhead maintenance unit  100  and is coupled to the outlet  108  through air hoses or another air conduit. In some embodiments, one air compressor supplies pressurized air to a plurality of printhead maintenance units for maintenance operations on a plurality of printheads in a printer. In the pressurized air emitter  104 , the pressurized air source  112  generates an air pressure through the outlet  108  of approximately sixty pounds per square inch (PSI). Alternative pressurized air emitter embodiments generate greater or lesser air pressure outputs. 
     In the printhead maintenance unit  100 , the wiper assembler  132  includes an actuator  136 , piston  140 , and a wiper blade  144 . The actuator  136  is mechanically coupled to the wiper blade  144  via the piston  140 . In wiper assembly  132 , the actuator  136  is a pneumatic actuator driven by pressurized air delivered through couplings  138 . In another embodiment, the actuator is a hydraulic actuator driven by a hydraulic fluid delivered through hydraulic couplings similar to the couplings  138 . In still another embodiment, the actuator is an electric motor that is driven by an electrical current. The wiper blade  144  is oriented with an upward angle to engage the printhead face  508  at a location above the inkjet nozzles  510 . The wiper blade  144  has a width that corresponds to the width of the printhead face  508 . As depicted below, a positioning system moves the printhead maintenance unit  100  and the wiper blade  144  into engagement with the printhead  500  at various locations on the printhead face  508 . The wiper blade  144  includes a rubberized tip that conforms to the surface of the printhead face  508  and pushes ink on the surface of the printhead face  508  downward onto the drip bib  512 . 
     With reference to  FIG. 1  and  FIG. 2 , during a printhead maintenance operation, the actuator  136  moves the wiper blade  144  in direction  150  to a first position where the wiper blade  144  extends past the outlet  108  in the pressurized air emitter  104 . The wiper blade  144  engages the face of a printhead, such as printhead face  508 , and wipes ink on the printhead face  508  downward in direction  220  toward the drip bib  512 , while the outlet housing  106  remains at a predetermined distance from the printhead  500 . The actuator  136  retracts the wiper blade  144  in direction  148  to enable the maintenance unit  100  to move up and down the height of the printhead  500  in directions  222  and  220 , respectively, while the wiper  144  does not engage the printhead  500 . The pressurized air emitter  104  is configured to generate pressurized air that is directed onto the drip bib  512  both when the wiper  144  engages the printhead face  508  and when the wiper  144  is disengaged from the printhead face  508 . As depicted in  FIG. 2 , the outlet housing  106  moves to a position proximate to the top edge  514  of the drip bib  512  and the pressurized air emitter  104  directs pressurized air onto the drip bib  512  and away from the inkjet nozzles  510 . This air stream urges residual ink on the drip bib  512  toward the downward pointed tips  516 A- 516 D on the lower edge of the drip bib  512 . 
     In a printer embodiment that includes a plurality of printheads, a printhead maintenance system includes a corresponding plurality of printhead maintenance units that engage the multiple printheads during a maintenance operation.  FIG. 3  depicts an exemplary arrangement of printheads  500 A- 500 D in a printhead array  300  and an arrangement of printhead maintenance units  100 A- 100 D arranged in a printhead array maintenance unit  330 . In  FIG. 3 , each of the printheads  500 A- 500 D has substantially the same configuration as printhead  500 , and each of the printhead maintenance units  100 A- 100 D has substantially the same configuration as the printhead maintenance unit  100 . 
     The printhead array  300  houses the printhead  500 A- 500 D and further includes docking balls  310  and  314  that are connected to carriage support members  308  and  312 , respectively. The docking balls  310  and  314  are configured to engage docking members  370  and  380 , respectively, in the printhead array maintenance unit  330 . The carriage members  308  and  312  hold the printhead array  300  in a fixed position in engagement with the printhead array maintenance unit  330  during a maintenance operation. The printhead array  300  moves into engagement with the printhead array maintenance unit  330  during a maintenance operation, and moves out of engagement from the printhead array maintenance unit  330  during printing operations. 
     Some printer embodiments include a plurality of printhead arrays similar to the printhead array  300 . Alternative printhead arrays include a greater or lesser number of printheads, and a single printer can include printhead arrays with different numbers of printheads. For example, a printer that includes the printhead array  300  can also include alternating printhead arrays that include three printheads arranged in a staggered configuration with the printheads  500 A- 500 D depicted in  FIG. 3 . 
     The printhead array maintenance unit  330  houses the printhead maintenance units  100 A- 100 D and further includes support members  344  and  346 , a moveable beam  384 , actuator  392 , and an ink receptacle  340 . The support members  344  and  346  provide support for the moveable beam  384  and printhead maintenance units  100 A- 100 D and for the ink receptacle  340 . As described above, the docking members  370  and  380  formed in support members  344  and  346 , respectively, enable the printhead array  300  to engage the printhead array maintenance unit  330  during maintenance operations. Once docked with the printhead array maintenance unit  330 , the drip bib  512  in each of the printheads  500 A- 500 D is located at a predetermined distance from the pressurized air outlet  108  in each of the printhead maintenance units  100 A- 100 D, respectively. In the embodiment of  FIG. 3 , a distance of approximately one centimeter separates the pressurized air outlet from each drip bib  512 . 
     The ink receptacle  340  houses an ink collection reservoir  342  that collects purged ink from the printheads  500 A- 500 D. During a printhead maintenance operation, the printheads  500 A- 500 D move past a front wall  348  of the ink receptacle  340  to position the drip bib  512  in each of the printheads  500 A- 500 D over the ink collection reservoir  342 . Purged ink from the printheads  500 A- 500 D enters the ink collection reservoir  342 . The ink collection reservoir  342  also captures ink that is removed from the drip bib  512  by the pressurized air emitters  104  in each of the printhead maintenance units  100 A- 100 D. 
     The printhead array maintenance unit  330  includes a positioning system that has an electrical actuator  392 , moveable beam  384 , and tracks  388  formed in each of the support members  344  and  346 . The moveable beam  384  moves up and down in directions  222  and  220 , respectively, along the tracks  388  in response to the operation of the electrical actuator  392 . The moveable beam  384  is fixedly engaged to the printhead maintenance units  100 A- 100 D. Consequently, the wiper blade  144  and pressurized air outlet  108  in each of the printhead maintenance units moves up and down in directions  222  and  220 , respectively, with the moveable beam  384 . During a printhead maintenance operation, the actuator  392  moves each of the printhead maintenance units  100 A- 100 D with reference to printheads  500 A- 500 D, respectively. 
     Operation and control of the printhead array  300 , printhead array maintenance unit  330 , and optionally other components and functions of an inkjet printer are performed with the aid of a controller  328 . The controller  328  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 controllers and/or print engine to perform the functions, such as the difference minimization function, described above. 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. Alternatively, the circuits can be implemented with discrete components or circuits provided in VLSI circuits. Also, the circuits described herein can be implemented with a combination of processors, ASICs, discrete components, or VLSI circuits. 
       FIG. 4  depicts a printhead maintenance process  400 . As used in this document, a reference to a process performing or doing some function or event refers to a controller configured with programmed instructions and electronic components operatively connected to the controller performing the function or event by executing the instructions and/or operating one or more components. Process  400  is described with reference to the printhead array  300 , printhead array maintenance unit  330 , and controller  328  of  FIG. 3  for illustrative purposes. 
     Process  400  begins by activating the heater  530  in each of the printheads  500 A- 500 D (block  404 ). The heater  530  elevates the temperature of the face  508  and the drip bib  512  in each printhead to a temperature that is above the melting point of the ink formed on the exterior of each printhead. In some embodiments, the elevated temperature is greater than a temperature of the ink that enables the ink to melt for use in printing operations. For example, a phase-change ink is heated to a temperatures of approximately 115° C. during a printing operation. The phase-change ink melts at 115° C. and inkjets in the printhead  500  eject drops of the melted ink through the inkjet nozzles  510 . Process  400  heats the printhead  500  and ink on the printhead face  508  and  512  to a higher temperature than the temperature used for printing operations. In one embodiment, the heater  530  elevates the temperature of the printhead  500  to approximately 130° C. The increased temperature of the printhead  500  enables the phase-change ink to remain in a liquid state as pressurized air is directed onto the drip bib  512 . 
     In some embodiments, the pressurized air has a temperature that is below the elevated temperature of the printhead  500 . The elevated temperature of the printhead  500  enables the ink to remain liquefied even if the lower-temperature pressurized air reduces the temperature of the printhead  500 . As is known in the art, the pressurized air expands and cools after leaving the outlet  108  in the pressurized air emitter  104 . In the example of printhead  500 , the temperature range of the pressurized air as the pressurized air contacts the drip bib  512  is between approximately 15° C. and 115° C. to clean liquid ink from the drip bib  512 . Alternative embodiments can operate with higher or lower pressurized air temperatures based on various factors including the melting and boiling points of the phase-change ink, level of applied air pressure, temperature of the drip bib, and thermal mass of the drip bib and printhead. 
     In other embodiments, the pressurized air is heated prior to being applied to the drip bib  512 . In embodiments that employ heated pressurized air, the printhead heater  530  can heat the printhead  500  to the temperature used for printing operations, or does not heat the printhead  500  when the heated pressurized air melts the phase-change ink on the drip bib  512 . 
     As part of a printhead maintenance operation, process  400  engages the wiper in each printhead maintenance unit  100  with the printhead face  508  at a location above the inkjet nozzles  510 , and moves the outlet  108  of the pressurized air emitter  104  to a position proximate the top edge  514  of the drip bib  512  (block  408 ).  FIG. 2  depict the position of the printhead maintenance unit  100  engaged to the printhead  500 . In the wiper assembly  132 , the actuator  136  moves the wiper blade  144  in direction  150  to engage the wiper blade  144  with the printhead face  508 . 
     Once the wiper blade  144  engages the printhead face  508 , the pressurized air emitter  104  begins application of pressurized air onto the drip bib  512  (block  412 ). In one embodiment, the pressurized air source  112  activates and the pressurized air is directed toward the drip bib  512  through the outlet  108 . In another embodiment, the pressurized air source is already activated and the valve  118  opens to enable pressurized air to flow through the conduit  116  and the outlet  108 . 
     Process  400  continues as the printhead maintenance unit  100  moves downward to wipe the printhead face  508  and apply pressurized air to the drip bib  512  (block  416 ). The controller  328  operates the actuator  392  and the moveable beam  384  and printhead maintenance units  100 A- 100 D move in direction  220 . The wiper  144  pushes drops of liquid ink on the printhead face  508  toward the drip bib  512  to clean the printhead face  508 . In one embodiment, the actuator  392  moves each of the printhead maintenance units  100  at a velocity of approximately 0.5 millimeters/second. 
     In process  400 , the controller  328  repeatedly starts and stops the application of pressurized air from the pressurized air emitter  104  onto the drip bib  512  as the printhead maintenance unit  100  moves downward with respect to the printhead  500  (block  420 ). In one configuration, the controller  328  repeatedly activates and deactivates the pressurized air source  112  to start and stop the application of pressurized air to the drip bib  512 . In another embodiment, the pressurized air source  112  remains activated and the controller  328  opens and closes the valve  118  to start and stop the application of pressurized air to the drip bib  512 . The controller  328  repeatedly starts and stops the application of pressurized air toward the drip bib  512  in a predetermined sequence, such as starting and stopping the pressurized air at intervals of approximately one second. That is to say, the printhead maintenance unit  100  starts the application of pressurized air for one second, then stops the application for one second, and continues to start or stop the application of pressurized air each second as the outlet  108  moves down the drip bib  512 . The repeated starting and stopping of the pressurized air toward the drip bib  512  reduces the magnitude of a drop in temperature in the drip bib  512  that is produced by the application of pressurized air at a lower temperature than the elevated temperature of the printhead  500 . Thus, the phase-change ink on the drip bib  512  remains in a liquid phase as the printhead maintenance unit applies pressurized air to the drip bib  512 . An alternative embodiment applies the pressurized air to the drip bib  512  continuously until the printhead maintenance unit  100  has completed the wiping process. 
     As describe above, the pressurized air emitter  104  can emit pressurized air over a wide range of temperatures. The overall proportion of time that the pressurized air source applies air to the drip bib in process  400  can be proportional to the pressurized air temperature. For lower pressurized air temperatures, such as temperatures near 15° C., the pressurized air emitter  104  stops the application of pressurized air for comparatively longer periods so that the pressurized air does not cool and solidify ink on the drip bib  512 . For higher pressurized air temperatures, such as temperatures near 115° C., the pressurized air emitter  104  can operate for longer periods or operate continuously since the ink remains above the melting temperature on the drip bib  512 . 
     Once the wiper blade  144  has reached the bottom of the printhead face  508  and the pressurized air emitter  104  has reached the bottom of the drip bib  512 , the wiper  144  is disengaged from the printhead face  508  and the pressurized air emitter stops application of the pressurized air toward the drip bib  512  (block  424 ). In each of the printhead maintenance units  100 A- 100 D, the controller  328  operates the actuator  136  to withdraw the wiper  144  from a corresponding printhead  500 A- 500 D in direction  148 . 
     Process  400  continues by moving the pressurized air outlet  108  in the printhead maintenance assembly to a location proximate the top edge  514  of the drip bib  512  (block  428 ). The controller  328  operates the actuator  292  to and moveable support  384  to move the printhead maintenance units  100 A- 100 D in direction  222  to return of the printhead maintenance units  100 A- 100 D is in the position depicted in  FIG. 2 . Since the wiper  144  in each of the printhead maintenance units  100 A- 100 D is retracted, the printhead maintenance units  100 A- 100 D do not contact the printheads  500 A- 500 D while moving in direction  222 . 
     Process  400  moves the pressurized air emitter  104  down the drip bib  512  in a second pass by starting application of the pressurized air toward the drip bib (block  432 ), moving the pressurized air outlet  108  downward past the drip bib  512  (block  436 ), and repeatedly starting and stopping the application of pressurized air. The starting and stopping of the pressurized air application continues until the outlet  108  reaches the bottom of the drip bib  512  (block  440 ). With the exception that the wiper  144  is disengaged from the printhead face  508 , process  400  performs the processing described in blocks  432 - 440  in substantially the same manner as described above with reference to the processing described in blocks  412 - 420 , respectively. The second application of pressurized air onto the drip bib  512  removes additional ink that the wiper  144  deposits on the drip bib  512 . 
     Process  400  concludes by returning the printheads  500 A- 500 D to a lower operating temperature (block  444 ). In the printhead array  300 , the controller  328  adjusts the level of heat emitted by the heater  530  in each of the printheads  500 A- 500 D. In one configuration, the controller  328  maintains the printheads  500 A- 500 D at an elevated operating temperature that is below the printhead temperature of the printheads during the maintenance process. 
     In one alternative embodiment, process  400  omits the wiping of the printhead face  508  as described in process blocks  408 - 424  above. Instead, the printhead  500  is heated to the elevated temperature and the pressurized air source applies pressurized air to the drip bib to remove residual ink from the drip bib after the completion of a printhead maintenance process that is known to the art. The elevated temperature of the drip bib and the directed application of pressurized air onto the drip bib remove the residual phase-change ink from the drip bib, whereas previously known maintenance processes leave the ink on the drip bib. 
     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.