Patent Abstract:
An improved method of upgrading an image transfer engine such as, for example, an ink jet fluid printer or plotter using liquid ink, or a xerographic device using a liquid toner is disclosed. A removable ink flush tank/cartridge containing an ink cleaner is substituted for a removable ink tank, permitting complete cleaning of ink from the ink fluid flow paths in the engine. This results in less contamination of new inks with previously used inks in the engine.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to fluid ejection systems having fluid ejection heads and replaceable fluid supply cartridges. 
     2. Description of Related Art 
     Fluid ejection systems, such as, for example, ink jet fluid printers and plotters, have a fluid ejection head with a fluid supply, either integral with the fluid ejection head, or connected to the fluid ejection head. A fluid ejection head contains a plurality of fluid channels that carry fluid from the fluid supply, such as, for example, a fluid supply cartridge, to respective fluid ejecting nozzles. A maintenance/capping station is often provided in such fluid ejection systems. At the end of an ejection operation, the fluid supply cartridge and fluid ejection head face are placed opposite the maintenance/capping station. The maintenance/capping station includes a capping chamber and an associated suction pump communicating through a waste tank and conduit lines. The capping chamber is movable into and away from the fluid ejection head. The capping chamber is used to prime the fluid ejection head with fluid when connected to the fluid ejection head and suction is applied to draw fluid through the fluid ejection head openings, as well as to remove dried fluid, contaminants and gas bubbles from the fluid ejection head. 
     Fluid ejection systems, such as ink jet printers and plotters, typically use four different color fluids, such as, for example, the three subtractive primary colors of cyan, yellow and magenta, and the achromatic color black. Ink jet printers and plotters may use different numbers of ink supply cartridges, such as, for example, four separate ink supply cartridges or two ink fluid supply cartridges, one having three compartments for the primary color inks, and the other ink tank having black ink. Alternatively, one tank with four compartments may be provided for the four different color inks. 
     If the user of a fluid ejection system, such as an ink jet printer or plotter, changes an ink color or type of ink being used in the fluid ejection system, such as, for example, a change from certain subtractive primary inks to pantone color or photographic color inks, if the new ink is incompatible with the old ink, the quality of the printed product or printed image will be decreased, often to the point of being unfit for its intended use. One way to avoid ink incompatibility problems is to insure that new inks are backward compatible with older inks or different types of ink. Unfortunately, this is not always possible. 
     U.S. Pat. No. 5,634,170 to Knapp et al. discloses a method and apparatus for filtering and sensing a developer fluid in a printing or copying machine to ensure that developer fluid reclaimed from a developing process is free from contamination. In col. 7, lines 34-45, Knapp et al. teaches an advantage of having a filtering station when the color of toner at a developing station is changed to another color of toner, for example, when a specialty of custom color toner has been used in a developer housing and is replaced with another color toner. Knapp et al. points out that it is very important that the reclaimed fluid be free of the first color of toner so that the second color of toner is not contaminated with the first color of toner, especially when a dark colored toner is replaced with a light color toner. Knapp et. al also teaches a toner sump cleaning mode in col. 12, lines 5-17, where cleaned reclaimed fluid is circulated through the filtering/sensing process until the fluid in the toner sump is free from toner. Then another color toner can be added to the toner concentration holding station. Knapp et al. also teaches having cleaned fluid travel to the diluent holding station rather than to the toner sump when desired. 
     SUMMARY OF THE INVENTION 
     This invention provides systems and methods that allow incompatible fluids to be used in a fluid ejection system. 
     This invention separately provides systems and methods for flushing a fluid ejection head connected to a removable fluid supply tank. 
     This invention further provides systems and methods that flush a fluid ejection head using a fluid supply tank containing a flushing fluid. 
     This invention also provides systems and methods that flush a fluid ejector head using at least two distinct fluids contained in at least two fluid supply tanks that are separately used to flush the fluid ejector head. 
     This invention also conditions the fluid injector head and a maintenance/capping station of a fluid ejection system to fluids distinct from existing and/or previously used fluids. 
     The systems and methods according to this invention provide a simple, easy-to-use cleaning technique for fluid ejection systems, including ink jet printers, which does not involve a separate toner concentration holding station, a diluent holding station with separate diluent supply lines, a toner sump, or elaborate sensing equipment. 
     The systems and methods according to this invention modify known fluid supply cartridges by filling one or more of such fluid supply tanks with one or more of a flushing fluid an ejection-fluid ink miscible fluid, such that the fluid supply tanks become flush tanks. Depending on the composition of the original ejection fluid relative to the composition of the new or replacement ejection fluid, more than one flush fluid may be required to achieve an effective flushing of the old fluid from the fluid ejection system. In various exemplary embodiments, in situations where more than one flush fluid is required, one flush fluid may be used to flush the original ejection fluid from the fluid ejection head and/or the maintenance/cap mechanism of the fluid ejection system. The second flush fluid is then used to condition the fluid ejection head and/or the maintenance/capping station for the new ejection fluid. 
     In various exemplary embodiments, the fluid ejection systems and methods according to this invention employ a fluid ejection head that accommodates different ejection fluid supply tanks. In this case, a flush tank is loaded into the fluid ejection head in the same manner as the standard ejection fluid supply tanks. When the fluid ejection system is an ink jet printer, for example, the flush tank contains a colorless, or slightly tinted, fluid so that the flush tank can be distinguished from an ink supply tank. The flush tank cleaning and conditioning fluids are used to clean the fluid ejection head and/or the capping/maintenance station components. The waste tank portion of the capping/maintenance station is used to collect all fluids ejected into the maintenance/capping station, whether one or more fluid ejection heads are used. The fluid receiving caps and the fluid lines to the waste tank portion of the capping/maintenance station can also be cleaned using the flush fluids 
     These and other features of the invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various exemplary embodiments of this invention will be described in detail, with reference to the following figures, wherein: 
     FIG. 1 is a perspective view of a conventional ink jet fluid printer having a printhead and a capping/maintenance station; and 
     FIG. 2 is flowchart outlining one exemplary embodiment of a method for flushing a fluid ejector according to this invention. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The following detailed description of various exemplary embodiments of the fluid ejection systems according to this invention are in part directed to one specific type of fluid ejection system, an ink jet fluid printer, for sake of clarity and familiarity. However, it should be appreciated that the principles of this invention, as outlined and/or discussed below, can be equally applied to any known or later-developed fluid ejection systems, beyond the ink jet fluid printer specifically discussed herein. 
     FIG. 1 shows one exemplary embodiment of an ink jet printer  10  that uses one or more ink supply containers  18  connected to the fluid ejector  20 . The ink jet printer  10  also includes a capping/maintenance station  30  that includes a cap chamber  33  usable to cap fluid ejector  20 . At the end of a fluid ejection operation, the scanning carriage (not shown) is parked in a maintenance position confronting the maintenance station  30 . The maintenance station includes a chamber  33  and an associated suction pump  32  in communication with each other through a waste tank  31 . The fluid lines  35  and  36  interconnect the interior of the chamber  33  with the waste ink tank  31  and the waste ink tank  31  with the suction pump  32 , respectively. The chamber  33  is movable toward and away from the fluid ejection head  20 . 
     Routine maintenance performed to clean debris, including dried ink and other materials, from each fluid ejector  20  is performed by covering each fluid ejector  20  with the corresponding cap of the capping/maintenance unit  30 . Ink flows through the fluid ejector  20 . Contaminants, including contaminated ink, are collected in the capping maintenance unit  30  and are drained by suction from the suction pump  32  into the waste ink tank  31 . The capping/maintenance station unit  30  may be used to cap the fluid ejector  20  when the ink jet printer  10  is idle, to reduce evaporation from, and drying of, ink in the fluid ejector  20 . 
     As an ink cleaning liquid, the flush fluid may be made up of one or more ink solvents without ink dye or pigment particles, or contain such low amounts of ink so as to constitute an indicator of the type ink with which the cleaning liquid is to be used, but not enough ink to materially contaminate other inks to be used later in the printer  10 . The ink cleaning liquid may contain surfactants and/or chelating agents that allow adsorbed contaminants and deposits to be relatively easily removed from the fluid ejector  20  and from other fluid passageways in the ink jet printer  10 . When used by a customer, the flush fluid supply cartridges are installed in the fluid ejector  20  in place of the original ink tanks  18 . 
     The user then operates the ink jet printer  10  to clean the fluid circuit of the ink jet printer  10 . A fluid circuit “clean” function may be performed directly with a user interface of the ink jet printer  10  such as, for example a touch screen, indirectly via a self-contained separate controller, or via a separate computer such as, for example, a personal computer. The “clean” function flushes old, incompatible ink from the fluid ejector  20  and the maintenance/cap station  30  so that, ideally, all vestiges of “old” incompatible ink are removed. For example, when a user wants to install ink fluid supply cartridges which contain ink which is not fully compatible with the previously or currently installed ink supply tanks, the “clean” function may be performed through a user interface to clean the fluid ejector  20  and the cap/maintenance station  30  and the associated fluid conduits. 
     FIG. 2 shows a flowchart outlining one exemplary embodiment of a method for flushing a fluid ejector head according to this invention. A user starts the flush operation. A flush operation can be started by, for example, selecting a start operation activator, such as, for example, a push button or touch screen portion located on the printer. Alternatively such a selection may be made by way of a display on a personal computer device, or by any other suitable interface with a printer controller. 
     The flush operation begins in step S 100  and continues to step S 110 , where the fluid ejector  20  moves to a cartridge change position. Once the fluid ejector  20  is located at the position where the cartridge or ink tank  18  can be changed, that fact may be displayed on the printer or on an associated display, such, as for example, on a personal computer. Next, in step S 120 , the user then replaces one or more ink tanks  18  with one or more flush tanks. Once this is done, suitable sensing elements can signal that the flush tank(s)  18  have been inserted, and this information can also be displayed to a user. Then, in step S 130 , the user inputs a clean command to the printer directly or through a device, such as a computer, which is interfaced with the printer. Control then continues to step S 140 . 
     In step S 140 , the printer moves the fluid ejector  20  to the maintenance/capping station  30 . Then in step S 150 , the maintenance/capping station  30  pump is turned on. This can be done manually by the user via a button or other input device on the printer or via an interfaced computer, or it can be done automatically by the printer as part of a sequence of system flush commands. Next in step S 160 , the suction pump  32  flushes the fluid ejector  20  and/or the maintenance station  30 , including any fluid lines connecting the fluid ejector  20  and the maintenance station  30 , the waste ink tank  31  and the fluid lines  35  and  36  in the ink jet printer. Control then continues to step S 170 . 
     Flushing the fluid ejector  20  and/or these other elements can be accomplished by operating the flush pump for a predetermined amount of time, by flushing with a predetermined volume of cleaning fluid, and/or by real-time sensing a suitable parameter of the fluid, such as, for example, the optical density or electrical capacitance of the flushing fluid. In the last case, sensors (not shown) would be provided to detect a suitable parameter, such as, for example, the optical density or the electrical impedance or conductivity, of the ink flushed from the capping/maintenance station  30  and/or fluid ejection head  20 . These sensors would provide one or more signals to the printer to shut off the suction pump  32  to terminate the flush operation when a desired flush fluid characteristic is achieved. When the flush operation has been performed, the printer may indicate that the flush operation is completed by displaying, for example, a “flush complete” message or other suitable message. 
     In step S 170 , the fluid ejector  20  is moved to the cartridge change position. This can be done automatically or manually. Next, in step S 180 , a determination is made whether a second or subsequent flush cartridge  18  needs to be used. This determination can be made automatically, based on the user identifying the name or identifier of the new ejection fluid composition to be used, or in any other known or later-developed manner. Alternatively, this determination can be made manually, by prompting the user with a query regarding whether there is another flush cartridge  18  to be installed. 
     If another flush fluid supply cartridge  18  is to be installed, control continues to step S 190 , where the next flush cartridge is installed in place of the previous flush cartridge. Control then jumps back to step S 140 . In contrast, if not, control jumps to step S 200 , where the user replaces the current flush ink fluid supply cartridges  18  with new or upgrade ink fluid supply cartridges  18 . The printer may indicate that the flush fluid supply cartridges  18  have been replaced by ink fluid supply cartridges, i.e., by sensing a characteristic of the ink tank(s), such as, for example, a bar code label or any other known or later-developed method for encoding information into or onto the ink fluid supply cartridges  18 . Then, in step S 210 , once the replacement ink cartridge(s) have been inserted in place of the flush cartridges, the clean/flush operation is terminated. This may be accomplished automatically or manually. This operation results in an upgraded image transfer engine ready to use the new or upgraded ink without fear of contamination by the previously-used ink. 
     It should also be appreciated that the systems and methods of this invention can also be used with fluid ejection systems that do not have maintenance stations. In such fluid ejection systems, the fluid ejection heads are cleaned by firing fluid drops onto a receiving medium. This receiving medium is used in place of the waste fluid tank to receive and/or absorb the waste drops created during the cleaning process. This receiving medium is then discarded. 
     Likewise, in the systems and methods according to this invention, the flush fluid drops can be ejected onto a waste receiving medium in place of ejecting the flush fluid drops into the maintenance cap outlined above. In this case, only the fluid ejection head will need to be cleaned, and the maintenance station  30  and its various subsystems will be omitted. Likewise, steps S 140  and S 150  would be omitted, and step S 160  would be modified to merely flush the fluid ejector head  20 . 
     While this invention has been described in conjunction with the exemplary embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention.

Technology Classification (CPC): 1