This disclosure relates generally to inkjet printers, and more particularly to systems used in inkjet printers to remove purged ink from printheads.
In general, inkjet printers include at least one printhead that ejects drops of liquid ink onto a surface of an image receiving member. In an indirect or offset printer, the inkjets eject ink onto the surface of a rotating image receiving member, such as a rotating metal drum or endless belt, before the ink image is transferred to print media. In a direct printer, the inkjets eject ink directly onto print media, which may be in sheet or continuous web form.
In inkjet printers, the printheads are configured with an array of ejectors that are fluidly connected to an array of apertures in a face plate in a one-to-one correspondence. The ejectors are typically piezoelectric or thermal devices that are activated to eject one or more drops of ink from a chamber between the ejector and the aperture to which the ejector is connected. Sometimes, the viscosity of the ink, debris, or other issues can partially or completely block an aperture, the chamber, or the supply of ink to the chamber. To restore the ability of an ejector to eject ink drops through the aperture to which it is connected, printheads are purged. Purging refers to a pressure source being coupled to the pneumatic system within a printhead to urge ink through the chambers in the printheads and emit ink from the apertures of the printhead. This emitted ink is not expelled with sufficient pressure to escape the printhead, but rather remains on the face plate of the printhead.
To remove purged ink from the face plates of printheads, various systems have been developed that heat, wipe, or suction ink from the face plates. Some inks have special properties that make them especially difficult to remove from the face plates of printheads. For example, some printers include printheads that eject magnetic inks. These magnetic inks include solvents that dry quickly once exposed to ambient air and metal particles that can cling to the face plates. Improvements in systems that remove purged ink having special properties that make removal of the ink difficult are beneficial.
A printer disclosed in this document includes a system that removes most any type of purged ink from printhead faces. The printer includes a plurality of printheads arranged to eject ink across a width of an image receiving surface in a cross-process direction as the image receiving surface passes the plurality of printheads in a process direction, the plurality of printheads being operatively connected to an actuator and the actuator being configured to move the plurality of printheads in the cross-process direction past the image receiving surface; a wiper module having a reservoir configured to hold a cleaning fluid, at least one wiper, and at least one actuator operatively connected to the at least one wiper, the at least one wiper being configured to rotate the at least one wiper into the cleaning fluid held within the reservoir and into a position in which the at least one wiper can contact the plurality of printheads after the plurality of printheads has past the image receiving surface; a plurality of caps, each cap being configured to align with a printhead in the plurality of printheads when the plurality of printheads is positioned opposite the plurality of caps, each cap being operatively connected to an actuator to enable each cap to be moved to cover a face of the printhead aligned with the cap to enable the printhead covered by each cap to be purged and to enable each cap to be retracted from the printhead covered by each cap; a receptacle having a volume and a wiper positioned across a width of the receptacle, the receptacle being operatively connected to an actuator to enable the receptacle to be moved in a direction opposite the process direction to move the wiper across the plurality of printheads when the plurality of printheads is positioned opposite the plurality of caps, the wiper being positioned to enable the wiper to remove a portion of ink purged from each printhead in the plurality of printheads that has been purged without contacting the face of each printhead; and a controller operatively connected to the actuator that is operatively connected to the plurality of printheads, the actuator that is operatively connected to the receptacle, the actuator that is operatively connected to the plurality of caps, and the at least one actuator that is operatively connected to the at least one wiper. The controller is configured to: operate the actuator operatively connected to the plurality of printheads to move the plurality of printheads from a position opposite the image receiving surface to the position opposite the plurality of caps; operate the actuator operatively connected to the plurality of caps to move the caps in the plurality of caps to cover the face of each printhead in the plurality of printheads and to move the caps in the plurality of caps away from the face of each printhead in the plurality of printheads in response to the printheads in the plurality of printheads being purged; operate the actuator operatively connected to the receptacle to move the receptacle between plurality of caps and the plurality of printheads to remove the portion of the ink purged from the plurality of printheads and enable the removed portion of the ink to fall within the receptacle; operate the actuator operatively connected to the at least one wiper to move the wiper from the position within the reservoir to a position that enables the at least one wiper to contact the printheads in the plurality of printheads; and operate the actuator operatively connected to the plurality of printheads to move the plurality of printheads past the wiper module to enable the at least one wiper to contact the faces of the printheads in the plurality of printheads as the plurality of printheads moves past the wiper module to remove ink from the faces of the printheads in the plurality of printheads and to return the plurality of printheads to a position opposite the image receiving surface.
A method of operating an inkjet printer enables most any type of purged ink to be removed from printheads faces. The method includes operating with a controller an actuator operatively connected to a plurality of printheads to move the plurality of printheads from a position opposite an image receiving surface to a position opposite a plurality of caps; operating with the controller an actuator operatively connected to the plurality of caps to move the caps in the plurality of caps to cover the face of each printhead in the plurality of printheads and to move the caps in the plurality of caps away from the face of each printhead in the plurality of printheads in response to the printheads in the plurality of printheads being purged; operating with the controller an actuator operatively connected to a receptacle to move the receptacle between the plurality of caps and the plurality of printheads to remove a portion of the ink purged from the plurality of printheads and enable the removed portion of the ink to fall within the receptacle; operating with the controller an actuator operatively connected to at least one wiper to move the at least one wiper from a position within a reservoir to a position that enables the at least one wiper to contact the printheads in the plurality of printheads; and operating with the controller an actuator operatively connected to the plurality of printheads to move the plurality of printheads past the at least one wiper to enable the at least one wiper to contact the faces of the printheads in the plurality of printheads as the plurality of printheads moves past the at least one wiper to remove ink from the faces of the printheads in the plurality of printheads and to return the plurality of printheads to a position opposite the image receiving surface.
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 produce images made with one or more colorants on print media. Common examples of printers include, but are not limited to, xerographic and inkjet printers. Various printer embodiments use one or more marking materials, such as ink or toner, to form printed images in various patterns. An “image receiving surface” in this document refers to any surface that receives a marking material, such as an imaging drum, imaging belt, or various print media including paper. As used herein, the term “marking material” refers to a substance deposited on a substrate to form a printed image on the substrate. The marking material can be ink, for example aqueous or phase change inks, xerographic developer or toner particles, or any other substance used for forming an image on a substrate. The term “substrate” refers to a print medium, such as paper, that holds printed images. In some embodiments, the printer is a digital printer. Digital printers enable an operator to design and modify image data to alter the image printed on the substrate easily using, for example, commercially available image editing software.
A continuous feed or “web” printer produces images on a continuous web print substrate such as paper. In some configurations, continuous feed printers receive image substrate material from large, heavy rolls of paper that move through the printer continuously instead of individually cut sheets. The paper rolls can typically be provided at a lower cost per printed page than pre-cut sheets. Each such roll provides an elongated supply of paper printing substrate in a defined width. Fan-fold or computer form web substrates may be used in some printers having feeders that engage sprocket holes in the edges of the substrate. After formation of the images on the media web, one or more cutting devices separate the web into individual sheets of various sizes. Some embodiments use continuous feed printing systems to print a large number of images in a timely and cost efficient manner. As used herein, the term “magnetic ink” refers to an ink that includes a suspension of magnetic particles in a liquid or phase-change medium. Some magnetic inks include a suspension of particles, such as iron oxide, in an aqueous or organic based solvent.
The media can be unwound from the source 10 as needed and propelled by a variety of motors, not shown, rotating one or more rollers. The media conditioner includes rollers 12 and a pre-heater 18. The rollers 12 control the tension of the unwinding media as the media moves along a path through the printer. The pre-heater 18 brings the web to an initial predetermined temperature that is selected for desired image characteristics corresponding to the type of media being printed as well as the type, colors, and number of inks being used. The pre-heater 18 can use contact, radiant, conductive, or convective heat to bring the media to a target preheat temperature, which in one practical embodiment, is in a range of about 30° C. to about 70° C.
The media are transported through a print zone 20 that includes a series of printhead units 21A and 21B. Each printhead unit effectively extends across the width of the media and is able to place ink directly (i.e., without use of an intermediate or offset member) onto the moving media. Each of the printhead units 21A and 21B includes a plurality of printheads positioned in a staggered arrangement in the cross-process direction over the media web 14. As is generally known, each of the printheads can eject a single color of ink, one for each of the inks typically used in the printer 5. As used herein, “liquid ink” refers to inks formed with water as a solvent and include, but are not limited to, ink emulsions, ink suspensions, ink solutions, or the like. In the configuration illustrated in
The controller 50 of the printer receives velocity data from encoders mounted proximate to rollers positioned on either side of the portion of the path opposite the printhead units 21A and 21B to compute the position of the web as the web moves past the printheads. The controller 50 uses these data to generate timing signals for actuating the inkjets in the printheads to enable the different colors ejected by the printheads in the printhead units to be ejected with a reliable degree of accuracy for registration of the non-magnetic ink patterns to form single or multi-color images on the media. The inkjets actuated by the firing signals correspond to image data processed by the controller 50. The image data can be transmitted to the printer, generated by a scanner (not shown) that is a component of the printer, or otherwise electronically or optically generated and delivered to the printer. In various alternative embodiments, the printer 5 includes a different number of printhead units and can print inks having a variety of different colors.
Following the print zone 20 along the media path, the media web moves over guide rollers 26 to one or more “mid-heaters” 30. A mid-heater 30 can use contact, radiant, conductive, and/or convective heat to control a temperature of the media and the ink on the media. The mid-heater 30 brings the ink placed on the media to a temperature suitable for desired properties when the ink on the media is sent through the spreader 40. Following the mid-heaters 30, a fixing assembly 40 is configured to apply heat, pressure, or both to the media to fix the images to the media. The fixing assembly 40 includes any suitable device or apparatus for fixing images to the media including heated or unheated pressure rollers, radiant heaters, heat lamps, and the like. In the embodiment of
The fixing assembly 40 also includes a cleaning/oiling station 48 associated with the image-side roller 42. The station 48 cleans and/or applies a layer of some release agent or other material to the roller surface. The release agent material can be an amino silicone oil having viscosity of about 10-200 centipoises. Only small amounts of oil are required and the oil carried by the media is only about 1-10 mg per A4 size page. In one embodiment, the mid-heater 30 and fixing assembly 40 can be combined into a single unit, with their respective functions occurring relative to the same portion of media simultaneously. In another embodiment the media is maintained at a high temperature as it is printed to enable spreading of the ink.
Following passage through the media path, the printed media can be wound onto a roller for removal from the system. A rewind unit 90 winds the printed media web onto a take-up roller for removal from the printer 5 and subsequent processing. Alternatively, the media can be directed to other processing stations that perform tasks such as cutting, binding, collating, and/or stapling the media or the like.
Operation and control of the various subsystems, components and functions of the printer 5 are performed with the aid of the controller 50. The controller 50 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 described above and the processes 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. 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.
In order to both purge and clean ink from the printheads in the printhead units 21A and 21B, a purge and wipe system 200 has been developed. This system 200 is depicted in
The wiper assembly 204 includes four actuators 240, each of which is operatively connected to a rotatable cam 228 by a rotating shaft 224. The cams are configured with wipers as described below. The actuators are operated to rotate the wipers through a reservoir of cleaning fluid beneath the cams 228 and then to a position that enables each wiper to wipe the faces of two printheads in a single row of the printhead assembly 204. The removed ink falls into the reservoir, which has a slanted floor that enables the removed ink to slide along the floor to a drain 236. Cleaning fluid is provided to the reservoir through supply port 232. Printhead seal assembly 212 includes sealing caps, which are typically made of compliant material, such as silicone. These caps are operatively connected to an actuator 218 that lifts the caps into engagement with the faces of printheads when the printhead assembly 204 is moved to a position opposite the printhead seal assembly. Pressure is then applied to the internal reservoirs, manifolds and channels in the printheads to urge ink through the printheads and onto the faces of the printheads. The sealing caps are then lowered by the actuator 218 to enable actuator 260, which is operatively connected to the purge tray 216, to be operated by the controller 428 to move the purge tray 216 between the sealing cap assembly 212 and the printhead assembly 204. A wiper 244 is provided within the purge tray 216 to be close to, but not touch, the faces of the printheads 250 in the printhead assembly 204. When the assembly 204 is opposite the seal assembly 212, the wiper 244 in the tray 216 removes a substantial amount of ink remaining on the faces of the printhead after the purge. The floor of the purge tray 216 slants to the drains 248 to enable the removed purged ink to be collected in a waste receptacle, which is fluidly connected to the drains 248.
The system of
The wiper module 208 is shown in greater detail in
An end view of the container 404 is shown in partial cutaway in
In the process 700, a purge operation begins with the controller 428 operating the actuator 206 to move the printhead assembly past the wiper assembly 208 while the controller 428 operates the actuators 240 to rotate the cams to position the wipers within the cleaning fluid reservoir (block 704). The controller 428 stops the printhead assembly 204 when it is opposite the sealing cap assembly 212. After the controller 428 operates the actuator 218 to raise the caps 220 to seal the printhead faces, the ink is purged from the printheads (block 712). The controller 428 then operates the actuator 218 to lower the sealing caps and the controller operates actuator 260 to move the purge tray to the position between the sealing cap assembly 212 and the printhead assembly 204 (block 716). As the purge tray moves to the position opposite the printhead assembly, the wiper 244 removes a substantial portion of the purged ink remaining on the printhead faces. The controller 428 operates the actuator 260 to return the purge tray to its original position and during this retraction, the wiper 244 again removes ink from the printhead faces (block 720). Once the tray 216 returns to its original position, the controller 428 operates the actuators 240 to rotate the cams 228 so the wipers are positioned in the return path of the printheads to the printing position (block 724). As the controller 428 operates the actuator 206 to return the printhead assembly 204 to the printing position, the printhead assembly moves past the wipers on the cams 228 and the wipers contact the faces of the printheads (block 728). The wiping action coupled with the cleaning fluid on the wipers removes the remaining purged ink from the printhead faces. When the printhead assembly reaches the printing position from which it started, the controller 428 stops the printhead assembly 204 and the purging operation is completed. The printhead assembly is now ready for printing.
It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. 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.
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