Abstract:
A cleaning system for a fluid ejector arrangement employing a single roller for handling different fluids that should not be mixed. The single roller is divided into portions assigned to respective fluids. In embodiments, the single roller is used to clean a plurality of ejectors, in which case each section of the roller handles one ejector. In other embodiments, the single roller is used to clean a single ejector that ejects to a plurality of fluids, in which case each section of the roller handles one fluid. Still other embodiments can employ a plurality of ejectors and a plurality of fluids ejected from one or more of the ejectors, wherein each section of the roller is assigned to a particular fluid, whether the fluid be ejected from the same ejector or from a different ejector.

Description:
FIELD OF THE INVENTION 
     Embodiments relate to fluid ejector cleaning. In particular, embodiments relate to inkjet printer printhead cleaning. 
     BACKGROUND AND SUMMARY 
     Typical cleaning systems for ink jet printers include separate cleaning elements for each color of ink employed by the printer. The motivation to provide such duplicate cleaning elements is to prevent cross-contamination of ink colors. However, the use of multiple, substantially identical cleaning elements increases the cost and complexity of ink jet printers unnecessarily. Additionally, prior attempts at using a single cleaning element have resulted in cross contamination. This principle can be applied on broader basis to other types of ejection systems. Multiple ejectors ejecting fluids that should not be mixed can be cleaned using embodiments, as can a single ejector ejecting multiple fluids that should not be mixed. Embodiments employed in inkjet printers will be discussed for ease of description, but other types of ejectors can employ embodiments as well. 
     Some ink jet printer printheads that use water based inks, such as, for example, acoustic and thermal ink jet printheads, are difficult to clean. Ink jet printers that use such difficult-to-clean printheads employ cleaning systems that become soiled over time. These soiled cleaning systems typically must be replaced at regular intervals. Ink jet printers that use such difficult-to-clean printheads also typically use complex seal mechanisms at the printhead-cleaning system interface to prevent cleaning fluid from spilling or otherwise leaking at the interface. 
     Some cleaning systems use rotating cleaning rollers that dip into cleaning fluid contained in a cleaning chamber. In operation, a squeegee roller bears against the cleaning roller and squeezes out excess cleaning fluid. Then, a rotating cleaning roller bears against the printhead to apply cleaning fluid to the soiled printhead. The applied cleaning fluid dissolves and washes away dried ink, including dried ink plugs, paper dust and other printhead contaminants from the printhead orifices into the cleaning fluid in the cleaning chamber, where the dried ink and other contaminants are dissolved into the cleaning fluid contained in the cleaning chamber. 
     Problems with ink jet printhead cleaning systems include buildup of ink and/or other contaminants in the cleaning fluid with each cleaning cycle, and evaporation of water and other non-volatile liquids from the cleaning solutions during periods of non-use. These problems sharply reduce the useful life of cleaning fluids by increasing the concentration levels of ink in the cleaning fluid. 
     That is, the concentration ratio of ink to cleaning fluid in the cleaning fluid contained in the cleaning chamber increases as the cleaning fluid is used to clean the printhead. As a result, the cleaning fluid becomes less efficient at cleaning the printheads. After a certain number of cleaning cycles, the cleaning fluid resident in the cleaning chamber becomes too contaminated to effectively clean printheads. 
     Embodiments provide methods and systems that maintain the concentration of ink in the cleaning fluid throughout the life of the printer at levels where the effectiveness of the cleaning fluid in removing contaminants is not substantially impaired. 
     Embodiments separately provide systems and methods that compensate for and/or reduce the evaporation of volatile chemical compounds from the cleaning fluid. 
     Embodiments separately provide systems and methods that reduce the build-up of ink and/or other contaminants in the cleaning fluid. 
     In various exemplary embodiments, one or more of these features can be provided by, for example, pumping cleaning fluid into the printhead cleaning chamber only when one or more of the printheads need to be cleaned. After the printhead cleaning operation is completed, the cleaning fluid left in the cleaning chamber is removed from the cleaning chamber and sent to holding tanks. The holding tanks are closed containers in which the cleaning fluids are held to prevent evaporation of volatile materials in the cleaning fluid. 
     At various intervals, a known amount of contaminated cleaning fluid is removed from one or more of the holding tanks to a leach bed. The leach bed has a capacity to hold waste cleaning fluid bled to it from the holding tanks and is able to evaporate the waste cleaning fluid effectively over the life of the printer. A measured amount of fresh, i.e. uncontaminated, substitute cleaning fluid is then added into the one or more holding tanks from a corresponding cleaning fluid container. This results in maintaining the ink/cleaning fluid concentration in the holding tanks within ranges that result in effective long term cleaning of the printheads, for example, for the useful life of the printer. This can also compensate for any volatile compounds lost from the usable cleaning fluid due to evaporation. 
     In particular, embodiments employ a single cleaning roller to clean all printheads in an inkjet printer. This is achieved by allocating portions of the cleaning roller to each printhead. Similarly, embodiments can employ a single cleaning roller to clean ejectors that eject fluids that should not be mixed, even in the case where one ejector ejects multiple fluids that should not be mixed. 
     Embodiments employ a timing system that synchronizes the cleaning roller with the position of the printhead. The timing system ensures that the specific sections of the cleaning roller are properly aligned to selectively clean, for example, the C, M, Y and K printheads of an inkjet printer. This substantially reduces color mixing and cross-contamination of colors. 
     The main thrust of the invention is a scheme, whereby it is possible to use one “common” cleaning roller for the C, M, Y and K printheads. This is achieved by apportioning sections of the cleaning roller for a particular color printhead. This is done by synchronizing the rotary motion of the cleaning roll and the translatory motion of the printheads across the cleaning roll so that the same section of the cleaning roll is always in contact with a particular color printhead during the cleaning cycle. The action of the cleaning roll during the cleaning cycle is two-fold: dissolve the dried ink on the apertures as well as any debris/detritus during one half of the cleaning cycle and during the second half to transfer waste ink and other debris from the printhead to the cleaning solution in the cleaning chamber. 
     Synchronization of the cleaning roller rotary motion and the translatory motion of the printhead slide is accomplished by establishing a zero “start point” through the rotary encoder on the cleaning roller motor for the cleaning roller and a zero “start point” for the printhead slide through the linear encoder on the printhead slide. 
     A cheaper alternative might be a light interrupt sensor that senses a flag attached to a drive gear on the cleaner roll assembly. 
     While it is true that the cleaner roll transport waste inks of all colors into one common cleaning sump, the amount of waste ink per printhead is small on the order of 0.05 to 0.1 ml max per printhead per color in a cleaning sump fill with cleaning fluid (typically de-ionized water) with a capacity of 200-300 ml. 
     The concentration ratio of the ink/cleaning fluid is important. For effective cleaning, an ink/cleaning fluid ratio of no greater than 0.15 has been established. That means that if we take the 200 ml capacity conservative case, for instance, as much as 30 mls of waste ink of all colors can be dumped into the cleaning tank before the cleaning solution has to be replaced in toto. In other words, 150 to 300 cleaning cycles can be accomplished without having to change the cleaning solution. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a cleaning system according to embodiments of this invention. 
         FIG. 2  is a schematic flow diagram illustrating a method of cleaning according to embodiments. 
         FIG. 3  is a schematic flow diagram of other aspects of embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     As seen, for example, in  FIG. 1 , embodiments use a single cleaning roller  310  to handle cleaning of multiple fluids that should not be mixed from one or more ejectors  30 , such as a printhead. Either a single ejector of fluid, such as a printhead of an ink-jet printer, can eject more than one fluid that should not be mixed, or multiple ejectors can eject such fluids. The single cleaning roller  310  has sections allocated for each fluid and is controlled in conjunction with a timing system  40  that ensures that the proper section of the cleaning roller treated  310 , is aligned with a respective ejector  30 , of fluid that requires cleaning. In a color inkjet printer, for example, a single cleaning roller  310  can be used for C, M, Y and K printheads  30 , with timing means  40  synchronized with the position of the printhead that assigns specific sections of said cleaning roller to selectively clean the C, M, Y and K printheads to prevent color mixing and cross-contamination of colors. note that while embodiments will be described in the context of an inkjet printer, any fluid could conceivably be cleaned from a fluid ejector using embodiments. 
       FIG. 1  shows an exemplary embodiment of a cleaning system  10  for an ink jet printer in which embodiments can be employed. See, for example, U.S. Pat. No. 6,454,386, which is incorporated by reference. The ink cleaning system  10  includes a number of ink/cleaning fluid containers  100  that contain both ink to be provided to one or more printheads  30  and fresh, uncontaminated cleaning fluid. Each of the ink/cleaning fluid containers  100  has two chambers, one which holds ink and another which holds cleaning fluid. The ink jet printer is designed so that ink and/or cleaning fluid can be withdrawn from these dual-chambered containers  100 . 
     The dual-chambered containers  100  are fluidly connected by a conduit  120  and valve  500  via a number of conduits  121  to a holding tank  200 . A valve  210  is located in each of the conduits  121 . The holding tank  200  is connected to a bleed line  190  which is connected to a bleed valve  502 . The bleed valve  502  is connected to the leach pad  444  via the bleed line  276 . The leach pad  444  is an evaporative waste pad made of an absorbent material such as, for example, felt. 
     The cleaning system  10  includes a cleaning chamber  340 . In the prior art, cleaning chamber  340  typically has four separate compartments, each compartment being associated with one of the four printheads  30 . However, in embodiments of the instant invention, there is a single chamber  340  to service all printheads  30  and/or ink and cleaning fluid containers  100  provided in a particular device. The cleaning chamber  340  contains a cleaning roller  310  and a squeegee roller  320  and is connected to a pinch valve  330 . The pinch valve  330  is connected through a conduit  150  to a pump  400 , which can be, for example, a peristaltic pump. The pump  400  is connected through a conduit  170  and the valves  210  to the holding tank  200 . The cleaning chamber compartment  341  is connected through a conduit  140  to a second pump  402 , which may, for example, be a peristaltic pump. The second pump  402  is connected through a conduit  130  and one of the conduits  121  and a valve  210  to the holding tank  200 . 
     Instead of four separate cleaning compartments in the cleaning chamber  340 , embodiments provided respect of sections of the cleaning roller  310  for each ejector/printhead  30 . In inkjet printer employing black and three colors, for example, one section of the roller is assigned to each of black and the three colors. In the exemplary embodiment shown in  FIG. 1 , if multiple chambers were used, the peristaltic pump  400  would be used for the three chromatic colors, while the other peristaltic pump  402  would be used for the achromatic color (black). However, a pump may be provided, for example, for each individual color, or one pump could be provided to handle all cleaning compartments as seen in the Fig. Moreover, if there were no need for separate cleaning fluids for separate inks, only one holding tank need be provided, as is seen FIG.  1 . 
     When the printheads  300  need to be cleaned, the peristaltic pumps  400  and  402  are run in a first direction to pump the cleaning fluid from the holding tank  200  to the cleaning chamber compartments  341 . The holding tank vents are open during this operation. The cleaning roller  310 , especially the section(s) of the roller that will be used to clean the particular printhead(s)  300  and/or the particular fluid(s), pick up the cleaning fluid. The squeegee roller  320  removes excess cleaning fluid and the squeegeed cleaning roller  310  then applies the cleaning fluid to the printhead(s)  300  to clean it/them. 
     The peristaltic pumps  400  and  402  then pump the used or contaminated cleaning fluid from the cleaning chamber compartment  341  to the holding tank  200 . The holding tank vents are also open during this operation, then closed to prevent evaporation of volatiles from the cleaning fluid in the holding tank  200 . 
     One advantage of this cleaning system  10  is that the cleaning system  10  can be made a permanent part of an ink jet printer. Because the cleaning system  10  is a permanent part of the ink jet printer and does not become significantly contaminated, there is no need to replace the cleaning system  10 , or parts of the cleaning system  10 , over the life of the ink jet printer. One advantage of the dual chamber containers  100  that contain an ink and a cleaning fluid, is that replacing any one or all of the dual chambered ink/cleaning fluid cartridges  100  provides a constant supply of fresh cleaning fluid. 
     The leach pad  444  is designed to absorb a significant amount of cleaning fluid without overflowing during the portion of the cleaning cycle in which cleaning fluid is bled from the tank  200  and to release the absorbed amount of cleaning fluid to atmosphere in between cleaning cycles so that by the time a cleaning cycle is resumed, including bleeding cleaning fluid from one or more holding tanks, the leach pad  444  will be able to absorb all of the fluid bled from the one or more holding tanks without overflowing and evaporate the fluid to atmosphere prior to the next cleaning cycle. 
       FIG. 2  is a schematic flow diagram outlining one exemplary embodiment of a method for cleaning printheads according to this invention. Beginning in block S 100 , control continues to block S 110 , where a determination is made of whether one or more printheads need cleaning. If at least one printhead needs cleaning, control continues to block S 115 , where the proper section of the cleaning roller is rotated into the cleaning fluid supply. Control then passes to block S 120 . Otherwise, if a determination is made that no printhead needs cleaning, control returns to block S 110 . 
     In block S 120 , cleaning fluid is moved from one or more holding tanks to a cleaning chamber. Next, in block S 130 , one or more of the printheads is cleaned using the cleaning fluid in the cleaning chamber. Then, in block S 140 , the used cleaning fluid is removed from the cleaning chamber and returned to one or more of the holding tanks. Control then continues to block S 150 . 
     In block S 150 , a fractional amount of used cleaning fluid to be drawn from the one or more holding tanks and forwarded to a leach pad is determined. Additionally, in block S 150 , an amount of fresh, uncontaminated cleaning fluid to be added to the used cleaning fluid in the one or more holding tanks to achieve a cleaning fluid with a contaminant-to-cleaning fluid concentration which will effectively clean the printheads is determined. Then, in block S 160 , a determination is made whether to draw off or bleed the determined amount of used, contaminated cleaning fluid from the one or more holding tanks, and to add the determined amount of fresh, uncontaminated cleaning fluid to those one or more holding tanks. This determination may be made based on the amount of contamination actually present or estimated to be present in the contaminated cleaning fluid, the capacity of the leach pad, the amount of uncontaminated cleaning fluid available, and/or the cost-effectiveness of reconstituting the cleaning fluid each cycle or every other cycle, or every third cycle, etc. If, in block S 160 , the fractional amount of contaminated fluid is to be drawn off, control continues to block S 170 . Otherwise, control jumps back to block S 110 . In block S 170 , the determined fractional amount of contaminated cleaning fluid is drawn from the holding tank to the leach pad and the determined amount of uncontaminated fluid is added to the holding tanks. Control then returns to block S 110 . 
     The determination of the amount of used, contaminated cleaning fluid to be bled from one or more holding tanks, and of the amount of fresh, uncontaminated cleaning fluid to be added to one or more holding tanks, may be accomplished in several ways. In one illustrative method, an empirical method is used. In order to determine how much contaminated cleaning fluid to remove and how much fresh cleaning fluid to add in this illustrative method, tests are run to determine how much ink can be in the cleaning solution and still have the cleaning solution effectively clean the printheads. If the cleaning solution is simply recycled without adding any additional cleaning solution, a point is reached where the ink contaminated cleaning solution can no longer effectively clean the printheads. Once that point is reached, a sample of the ink contaminated cleaning solution can be transferred from the cleaning container to the holding tank and then purged from the holding tank into a container. The optical density of the ink contaminated cleaning solution can be compared with the optical density of one or more cleaning solutions with various amounts of ink added to those cleaning solutions. When the optical density of the sample drawn from the printer matches that of the cleaning solution with a known amount of ink contamination, the amount of ink contamination which renders the cleaning solution ineffective is known. In this manner, or in similar manners, one can determine how much cleaning solution to add to the recycled cleaning solution to maintain a recycled cleaning solution with contaminants at an ink-to-cleaning solution ratio which will continue to effectively clean printheads. Adding cleaning solution to the recycled ink contaminated cleaning solution is accomplished in the holding tanks. 
     For example, in one exemplary embodiment of the systems and methods according to this invention, if it is determined that, on average, a printhead cleaning cycle results in addition of ink and other contaminants which constitute 5% by volume of the cleaning solution, and no degradation in printhead cleaning effectiveness occurs until those contaminants constitute 15% or more by volume of the cleaning solution, a fractional portion of the contaminated cleaning solution, for example, 5% by volume of contaminated cleaning fluid, may be removed from the holding tank, and a similar amount of fresh cleaning solution added every other cleaning cycle. Alternatively, for example, 2.5% by volume of contaminated cleaning fluid may be removed every cleaning cycle from the holding tank, and a corresponding amount of fresh cleaning solution added. In another exemplary embodiment, the optical density of the recycled cleaning fluid, e.g., in the holding tanks, can be monitored. When the monitored optical density reaches a certain value, which indicates that the contaminants are approaching 15% by volume of the recycled cleaning fluid, then a suitable fractional amount of the contaminated cleaning solution could be removed from the holding tanks or any other suitable location in the system and/or a suitable amount of fresh cleaning fluid added to reduce the contaminated cleaning solution to an optical density which was known to result in effective printhead cleaning. Care must be taken, however, so that the amount of fluid bled from the one or more holding tanks is within the capacity of the leach pad to absorb without overflowing, and which can be evaporated before more cleaning fluid is bled to the leach pad from the one or more holding tanks which could cause overflowing of the cleaning fluid from the leach pad. 
     If the amount of ink which is cleaned from the printhead and which enters the cleaning fluid is up to 15% by volume of the cleaning fluid, no observable reduction in the ability of the cleaning solution to adequately clean the printhead occurs. If the amount of ink which is cleaned from the printhead and which enters the cleaning fluid is between 15% and 30% of the volume of the cleaning fluid, only a slight reduction in the ability of the cleaning fluid to adequately clean the printhead occurs. However, if the amount of ink cleaned from the printhead and which enters the cleaning fluid is above 30% by volume, the ability of the cleaning solution to adequately clean the printhead begins to be significantly reduced. 
     As indicated above, the systems and methods according to this invention attempt to maintain a desired concentration of ink to cleaning fluid in the cleaning chamber to achieve effective printhead cleaning. After the printhead cleaning operation is completed, the cleaning fluid left in the cleaning chamber is removed from the cleaning chamber and sent to holding tanks, which are closed containers where the cleaning fluids are held to prevent evaporation of volatile materials in the cleaning fluid. 
     In various exemplary embodiments of the ink jet purging head cleaning systems and methods according to this invention, purging about 2.5% by volume of the used cleaning solution returned from the cleaning container to the holding tank and into the leach bed  444 , and adding fresh cleaning solution in an amount of about 4% by volume of the amount of used cleaning solution returned from the cleaning container to the holding tank results in maintaining the contaminant to cleaning solution ratio of cleaning solution below 10% on a long term basis, such as, for example, over 2500 cleaning cycles. This is considered to maintain the ink/cleaning fluid concentration within a range which results in effective cleaning of printheads over the average life of an ink jet printer. 
     In a second illustrative embodiment, step S 150  may involve the use of a real time sensor, which can be used to make an actual measurement of the degree of contamination of the cleaning solution. 
       FIG. 3  shows in greater detail one exemplary embodiment of a method for making the determinations of step S 150 . As indicated above, in step S 150 , a determination of (1) the fractional amount of contaminated cleaning fluid to be drawn from the holding tank(s) and (2) the amount of uncontaminated cleaning fluid to add to the holding tank(s) is made. Thus, beginning in step S 150 , control continues to step S 151 , where a determination is made whether an actual measurement was made of the contaminant level of the cleaning fluid. If such a measurement was not made, control jumps to step S 154 . Otherwise, control continues to step S 152 . 
     In step S 152 , a determination is made whether the contaminant to cleaning fluid ratio is above a certain level, such as, for example, above x % by volume, where x is an empirically determined value. If the contaminant level is not above x % by volume, then control jumps to step S 154 . Otherwise, control moves to step S 153 . 
     In step S 153 , a determination is made to add y % by volume, where y is an empirically determined value, of uncontaminated cleaning fluid to, and draw off z % by volume, where z is an empirically determined value, of contaminated cleaning fluid from, one or more of the holding tanks. Control then passes to step S 155 . 
     In contrast, in step S 154 , a determination is made based on empirical data to add a % by volume, where a is an empirically determined value, of uncontaminated cleaning fluid to, and to bleed b % by volume, where b is an empirically determined value, of contaminated fluid from, one or more of the holding tanks. As indicated above, in various exemplary embodiments, b % was empirically determined to be about 2.5% by volume and a % was empirically determined to be about 4% by volume. Control then continues to step S 155 , which returns control to step S 160 . 
     When making an actual determination of the contaminant concentration, a sensor (not shown) may be placed anywhere in the system from, and including, the cleaning chamber to the holding tanks. The sensor may be, for example, an optical absorption detector or an electrical impedance detector, or an acoustic detector. The output from the sensor is compared with values obtained from a look-up table, for example, to determine how much used cleaning fluid to be drawn off and how much fresh cleaning fluid to be added to the used cleaning fluid to maintain a contaminant to cleaning fluid concentration ratio which will result in effective cleaning of the printheads. 
     If an actual, real time, determination of the contaminant concentration of the used cleaning fluid is not used, an empirical approach may be used. In this illustrative embodiment, the amount of used cleaning fluid to be drawn off and the amount of fresh cleaning fluid to be added to keep the contaminant to cleaning fluid ratio in an acceptable range over the expected life of the printer to achieve effective printhead cleaning is determined on a trial-and-error basis, as outlined above. These amounts can remain unchanged throughout the life of the printer or may be adjusted by a user should printhead cleaning not be acceptable. 
     One example of a cleaning solution used with this invention is de-ionized water which contains a small amount of co-solvent, such as, for example, N-methyl-Pyrrolidinone and trace bio-cide, such as, for example, sodium omadine or DOWICIL®. 
     Because the cleaning chamber  340 , which houses the cleaning rollers  310 , is not discarded or changed over the life of the printer, and there is no cleaning fluid circulating when the cleaning system  10  is not in use, there is little danger of spilling cleaning solution. Consequently, there is no need for complex sealing mechanisms at the interface of the cleaning rollers  310  and the printheads  300 . 
     The capacity of each holding tank is larger than the capacity of each cleaning chamber, so that regardless of the amount of fresh cleaning fluid added to the contaminated cleaning fluid, the holding tanks have sufficient capacity to add enough fresh cleaning fluid to maintain the concentration of ink to cleaning fluid at a level where the effectiveness of the cleaning fluid in removing contaminants from the printhead is not significantly impaired. 
     The size and composition of the leach bed  444  may vary depending on the capacity of cleaning fluid which is desired to be bled from the holding tanks at a given time, and on the ability of the leach bed to rapidly evaporate that fluid. In one exemplary embodiment, the leach bed is a container made of polypropylene of a rectangular shape with a capacity to hold at least 1000 ml of waste fluid at any given moment without dripping. The absorbent material is NOMEX® felt, but may be made of any suitable woven or non-woven material, natural or synthetic. The size of the absorbent pad is at least 1200 cc and is capable of absorbing and holding 1000 ml of water without overflowing. 
     The amount of contaminated cleaning fluid withdrawn from the cleaning system, which is bled out into the leach bed  444  for evaporation, and the amount of fresh cleaning fluid to be added to the cleaning system may be controlled by conventional microprocessor control based either on dynamic real time input from a device which measures a suitable cleaning fluid parameter, such as, for example, optical density, electrical impedance or acoustic absorption. 
     The main thrust of the invention is a scheme, whereby it is possible to use one “common” cleaning roller for the C, M, Y and K printheads. This is achieved by apportioning sections of the cleaning roller for a particular color printhead. This is done by synchronizing the rotary motion of the cleaning roll and the translatory motion of the printheads across the cleaning roll so that the same section of the cleaning roll is always in contact with a particular color printhead during the cleaning cycle. The action of the cleaning roll during the cleaning cycle is two-fold: dissolve the dried ink on the apertures as well as any debris/detritus during one half of the cleaning cycle and during the second half to transfer waste ink and other debris from the printhead to the cleaning solution in the cleaning chamber. 
     Synchronization of the cleaning roller rotary motion and the translatory motion of the printhead slide is accomplished by establishing a zero “start point” through the rotary encoder on the cleaning roller motor for the cleaning roller and a zero “start point” for the printhead slide through the linear encoder on the printhead slide. 
     A cheaper alternative might be a light interrupt sensor that senses a flag attached to a drive gear on the cleaner roll assembly. 
     While it is true that the cleaner roll transport waste inks of all colors into one common cleaning sump, the amount of waste ink per printhead is small on the order of 0.05 to 0.1 ml max per printhead per color in a cleaning sump fill with cleaning fluid (typically de-ionized water) with a capacity of 200-300 ml. 
     The concentration ratio of the ink/cleaning fluid is important. For effective cleaning, an ink/cleaning fluid ratio of no greater than 0.15 has been established. That means that if we take the 200 ml capacity conservative case, for instance, as much as 30 mls of waste ink of all colors can be dumped into the cleaning tank before the cleaning solution has to be replaced in toto. In other words, 150 to 300 cleaning cycles can be accomplished without having to change the cleaning solution. 
     It is appreciated that various other alternatives, modifications, variations, improvements, equivalents, or substantial equivalents of the teachings herein that, for example, are or may be presently unforeseen, unappreciated, or subsequently arrived at by applicants or others are also intended to be encompassed by the claims and amendments thereto.