Abstract:
In a method and apparatus, ink tubes are flushed by replacing a plurality of components of an ink delivery system with a plurality of purging components. Purging is controlled In response to the replacement of the components, wherein purging fluid is introduced into the inlet end of a tube in an ink delivery system, a printhead is operated to cause the purging fluid to flow through the tube and be expelled by the printhead, and the purging fluid is collected. Each of the components is provided with identifying information which can be provided to a microprocessor in the apparatus.

Description:
FIELD OF THE INVENTION 
     This invention relates to inkjet printers, and in particular to a method and apparatus for flushing ink tubes in an inkjet printer. 
     BACKGROUND OF THE INVENTION 
     Conventional inkjet printers have typically employed a self-contained printing cartridge, composed of a reservoir and printhead in one unit. Ink from the reservoir flows into a number of chambers in the printhead. The chambers are then quickly heated causing the ink to expel onto a printing media, for example, paper, acetate, cloth, etc. A separate printhead-cleaning device is utilized to clean the printhead by providing at least one wiper, over which the printhead passes, to wipe off any accumulated ink, ink residue or fibers remaining from the media being printed upon. 
     Over time inkjet printing has become more sophisticated, and now delivers the capability to print in any number of colors, complicated graphic designs, utilizes a vast number of different fonts, and is able to print photographs. As a result, later generation printers, especially large-format ones, consume more ink and utilize different ink compositions. 
     In order to accommodate higher ink consumption without having an operator change cartridges more often, the “all in one” printing cartridge has evolved to a more complex ink delivery system. The system includes a printhead, an ink reservoir, a printhead cleaning device (collectively referred to as printing components) and a tube connecting the reservoir to the printhead. The ink reservoir is usually easily replaceable and typically holds a larger quantity of ink than the printing cartridge design. 
     The number of ink compositions available for use in ink jet printers has also increased in order to provide the number of colors and photographic quality desired by users. However, some new ink compositions are incompatible with previous ink compositions. For instance, installing an ink cartridge with a new ink composition, while an old ink is present in the tubing or printhead, may result in the new ink composition combining with the old ink composition to form a precipitate, clogging the tubing or the printhead. Also, other problems may occur when installing an ink cartridge with a new ink composition, while the old ink is still present in the tubing and printhead of the printer, if the properties of the new ink are altered. This can be an especially severe problem when the new ink has a different color than the previously used ink. Thus, until the old ink is purged, print quality generally suffers. In general, any time a new ink composition is to be used in place of a non-identical ink composition, a potential incompatibility issue is presented (e.g., different colors, densities, solvents, pigments, surfactants, etc.). 
     In order to provide larger quantities of ink and multiple compositions of ink, printer manufacturers offer multiple printheads supplied by multiple reservoirs. However, because it is impractical to supply every type of ink desired in a particular printer, users must still change inks with all the incompatibility problems mentioned above. In printers utilizing a reservoir separate from the printhead, it is desirable to be able to change inks without mixing a new ink with an old ink. 
     One solution to the problems associated with incompatible ink compositions is to change the printing components, i.e. the reservoir, printhead, printhead cleaner, and the associated tubing during each ink change. By example, a printer utilizing separate reservoirs and printheads causes the printheads to regularly dock into a refill station. The reservoirs then connect to their corresponding printheads through short tubes which are integral to each reservoir. When changing ink types, a user may then change the reservoirs and tubes as a single assembly and also change the printheads and printhead cleaning devices. This system has the advantage of replacing all parts that contact the ink, thus eliminating any possible mixing of old ink and new ink. This method has a disadvantage in that it cannot be used on higher throughput printers where the tubing is more permanently routed inside the printer and difficult to access. 
     Another solution is to provide as many tubes in the printer as desired ink compositions. For example, if the user contemplates using eight different compositions of ink, then eight tubes are required. However, if later in time, additional ink compositions are desired, more tubes need to be installed. Anticipating the number of ink compositions and providing room for the contemplated tubing is impractical. 
     Another solution is to clean or purge the tubes of the previously used ink. In higher throughput printers where the tubing is more permanently routed inside the printer and difficult to access, this operation requires some disassembly of the printer in order to flush the tubes with distilled water. This procedure requires some provision for collecting the used distilled water and also requires some training for the operator and some protection against ink spillage. 
     It is desirable then to perform purging operations automatically, in order to minimize user intervention. Information devices may be incorporated into the printing components which identify them to a processor in the printer. A proposal to incorporate a parameter memory into ink jet printheads can be found in the publication entitled “Storage of Operating Parameters in Memory Integral with Print Head”, Lonis, Xerox Disclosure Journal, Volume 8, No. 6, November/December 1983. The author discusses storage of operating parameters to be used by a printer for calibration purposes, including drop generator driver frequency, ink pressure and drop charging values. 
     Also of interest is U.S. Pat. No. 5,138,344 to Ujita, entitled “Ink Jet Apparatus and Ink Jet Cartridge Therefor.” This patent indicates that an ink-containing replaceable reservoir can be provided with an integral information device (i.e., a resistor element, magnetic medium, bar code, integrated circuit or ROM), for storage of information relating to control parameters for an ink jet printer. 
     Accordingly it is an object of this invention to provide a method and apparatus for purging old ink from an ink delivery system in a printer and recharging the ink delivery system with new ink. 
     SUMMARY OF THE INVENTION 
     A method and apparatus are disclosed for purging a tube in an ink delivery system in a printer, where a purging fluid is introduced into the inlet end of the tube. The printhead of the ink delivery system is operated to cause the purging fluid to flow through the tube and be expelled by the printhead, and the purging fluid is collected. 
     A purging reservoir, a purging printhead, and a purging printhead cleaning device are provided for use in an ink jet printer having a replaceable ink reservoir, a replaceable printhead and a replaceable printhead cleaning device. The purging reservoir, purging printhead, and purging printhead cleaning device are installed in place of the respective replaceable printing components. The purging reservoir contains a purging solution for cleaning ink from the tubing in the printer which connects the reservoir with the printhead. Upon installation, a processor in the printer recognizes the purging printing components and initiates a purging procedure, cleaning old ink from the tubing and charging the tubing with new ink. 
     The purging reservoir, purging printhead, and purging printhead cleaning device may be incorporated into a kit. 
     The kit may also include a computer storage medium containing a program for use by a processor in the printer wherein the processor operates to control the purging procedure in accordance with the program. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a printer in accordance with the invention in cut-away form. 
     FIG. 2 is a schematic diagram of an ink delivery system. 
     FIG. 3 is a perspective view of a plurality of printheads positioned over a corresponding plurality of printhead cleaning devices. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A printer  10  in which this invention is practiced is shown in FIG.  1 . Printer  10  includes printing media  20 , for example, paper, mechanism for positioning media  30 ,and processor  40  for directing printer operations. FIG. 2 shows ink delivery system  50 , also included in printer  10 . 
     In FIG. 1 media positioning mechanism  30  feeds media  20  into a printing area, positions it for printing, that is, for receiving ink from ink delivery system  50 , and then ejects media  20  when printing is complete. Media  20  may be continuous, for example, in roll form, and in that case media positioning mechanism  30  may also incorporate a cutting mechanism for separating printed portions of media  20  from the continuous roll. 
     Processor  40  has control lines and an on-board memory, which are utilized to direct the activities of printer  10 . The on-board memory includes programs or procedures which processor  40  executes, either automatically or in response to input from an external device or an operator. Processor  40  preferably includes a facility  45  for receiving and storing additional programs contained on computer storage media  47 , such as a floppy disk drive, a compact disk drive, or a memory cartridge bay. 
     Turning now to FIG. 2, ink delivery system  50  includes at least one ink reservoir  60 , at least one printhead  70 , and at least one tube  80  which provides fluid communication between the ink reservoir  60  and the printhead  70 . Ink delivery system  50  also includes at least one printhead cleaning device  90 . Ink reservoir  60  is replaceable by other reservoirs  60 A,  60 B and ink delivery system  50  is adapted to receive a plurality of replaceable reservoirs containing one or more ink compositions. Printhead  70  and printhead cleaning device  90  are also replaceable and ink delivery system  50  is further adapted to receive a plurality of printheads and printhead cleaning devices. 
     In accordance with the invention, when an operator desires to use new ink composition  110  contained in new reservoir  60 B, replaceable reservoir  60  containing old ink  95  is first replaced with purging reservoir  60 A. Purging reservoir  60 A contains purging fluid  100  for purging tube  80  connecting purging reservoir  60 A and printhead  70 . Purging fluid  100  may be any fluid that is capable of purging tube  80  in accordance with a purging procedure as explained in greater detail below. Preferably, purging fluid  100  is a liquid vehicle, or solvent, compatible with both old ink composition  95  and new ink composition  110 . 
     Replaceable printhead  70  is also replaced with purging printhead  70 A that is configured to be compatible with old ink composition  95 , purging fluid  100 , and new ink composition  110 . Purging printhead  70 A is selected to perform a purging function and, as such, need not have full printing capabilities or be capable of meeting image quality standards for printing. 
     Further, replaceable printhead cleaning device  90  is also replaced with purging printhead cleaning device  90 A. Purging printhead cleaning device  90 A is capable of receiving and containing old ink composition  95 , purging fluid  100 , and new ink composition  110  to be expelled from purging printhead  70 A. Purging printhead cleaning device  90 A is further capable of containing old ink composition  95 , the purging fluid  100 , and new ink composition  110 , even if it is turned over or dropped. 
     Upon replacement of replaceable reservoir  60 , printhead  70  and printhead cleaning devices  90 , with purging reservoir  60 A, purging printhead  70 A and purging printhead cleaning device  90 A, respectively, processor  40  begins a purging procedure. Processor  40  directs purging printhead  70 A and purging printhead cleaning device  90 A to positions in close proximity to each other so that purging fluid  100  expelled from purging printhead  70 A is received by purging printhead cleaning device  90 A. FIG. 3 illustrates a plurality of purging printheads  70 A and a plurality of purging printhead cleaning devices in close proximity. 
     Returning to FIG. 2, processor  40  directs purging printhead  70 A to print continuously for a first time period, causing purging fluid  100  from purging reservoir  60 A to enter tube  80  and emptying tube  80  of old ink  95 . The first time period is selected to ensure that old ink  95  in tube  80  has been replaced by purging fluid  100 . Upon completion of the purging procedure, processor  40  then begins a recharging procedure. Purging reservoir  60 A is then replaced with new reservoir  60 B containing new ink composition  110 , and processor  40  again directs purging printhead  70 A to print continuously, for a second time period, emptying tube  80  of purging fluid  100  and causing the ink composition  110  from new reservoir  60 B to enter tube  80 . The second time period is selected to ensure that purging fluid  100  in tube  80  has been replaced by new ink  110  and may be the same as the first time period. 
     Upon completion of the charging procedure, purging printhead  70 A and purging printhead cleaning device  90 A are replaced with new printhead  70 B and new purging printhead cleaning device  90 B. 
     Purging reservoir  60 A, purging printhead  70 A and purging printhead cleaning device  90 A are each provided with an integral information device  120 ,  130 ,  140 , respectively, which contains identifying information for each printing component. The integral information device serves to convey information identifying the printing component and other information pertaining to the component&#39;s operation. For example, the information device may be a resistor, a bar code, a memory device, or a microprocessor. 
     Upon installation, using information device  120  on purging reservoir  60 A, processor  40  recognizes that purging reservoir  60 A has been installed and checks information device  130  on purging printhead  70 A and information device  140  on purging printhead cleaning device  90 A to ensure that they are suited for performing a purging procedure. If the correct components are not installed, processor  40  stops the purging procedure and notifies the operator. If the printing components are part of the set of components for performing a purging procedure, processor  40  then proceeds to identify the procedure to be utilized. If the procedure is not present in the memory of processor  40 , processor  40  requests that the operator load the procedure through the facility  45  for receiving and storing additional programs. If the procedure is present, processor  40  begins the purging procedure under program control. Because processor  40  is capable of identifying each printing component by its information device  120 ,  130 ,  140 , processor  40  has the capability of ensuring that the correct components are installed for each step of the procedure, and of stopping the procedure when the components are incorrect. 
     In some inkjet printers, the printhead is not removable and remains in place, regardless of the ink composition being used. In a further embodiment, then, printhead  70  is not replaced and remains in place during the purging and recharging procedure. Replaceable reservoir  60  and printhead cleaning device  90 , are replaced with purging reservoir  60 A and purging printhead cleaning device  90 A, respectively. Processor  40  then begins a purging procedure where processor  40  directs printhead  70  and purging printhead cleaning device  90 A to positions in close proximity to each other so that purging fluid  100  expelled from printhead  70  is received by purging printhead cleaning device  90 A. Processor  40  then directs printhead  70  to print continuously for a third time period, causing purging fluid  100  from purging reservoir  60 A to enter tube  80  and emptying tube  80  of old ink  95 . The third time period is selected to ensure that old ink  95  in tube  80  and any ink in the printhead has been replaced by purging fluid  100 . 
     Upon completion of the purging procedure, processor  40  then begins a recharging procedure as described previously but for a fourth time period, selected to ensure that both tube  80  and printhead  70  are emptied of purging fluid  100  and filled with ink composition  110  from new reservoir  60 B. Upon completion of the charging procedure, purging printhead cleaning device  90 A is replaced with new purging printhead cleaning device  90 B. 
     As can be seen from the above, incompatibility between different ink compositions may be avoided by purging the old ink from the ink delivery system. The purging procedure may be accomplished by having the operator change consumable printing components and may be done automatically, under program control. 
     Thus, while the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from its scope and spirit.