Patent Abstract:
Current fluid ejector maintenance techniques do not adequately deal with moveable debris particles present in the fluid supply manifold. Such moveable particles within the fluid supply manifold of a fluid ejector head can cause random ejection defects by clogging, restricting and/or blocking the channel inlets and/or filters present in the channel inlets, causing missed or misfired and/of misdirected drops. At least some of a plurality of fluid ejectors can be fired in a sequential pattern. Sequentially firing the fluid ejectors can move movable particles in the direction of the firing sequence. The moved movable particles can be deposited into non-operative areas within the fluid supply manifold, such as, for example, non-firing fluid ejection locations. The fluid ejectors can be fired in a sequential pattern within blocks of the fluid ejectors. For example, a fluid ejector head with 120 fluid ejectors can fire 1 out of every 20 fluid ejectors.

Full Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention is directed to systems and methods for maintaining and/or enhancing operation of fluid ejection systems. 
     2. Description of Related Art 
     Fluid ejection systems, such as drop on demand liquid ink printers, use various methods to eject fluids, including but no limited to piezoelectric, acoustic, phase change, wax based and thermal systems. These systems include at least one fluid ejector from which droplets of fluid are ejected towards a receiving medium, such as a sheet of paper. A channel is defined within each fluid ejector. The fluid is disposed in the channel. Droplets of fluid can be expelled as required from orifices or nozzles at the end of the channels using power pulses. 
     In some fluid ejection systems, such as, for example, drop on demand thermal ink jet printers, a pressurized reservoir of ink is connected to a plurality of ink channels and, subsequently, the nozzles, via a fluid supply manifold. The fluid supply manifold contains internal, closed walls defining a chamber with an ink fill hole. The fluid supply manifold receives ink from the ink reservoir and distributes it via internal passageways to the plurality of ejector channels. A plurality of sets of channels and associated fluid supply manifolds can be defined within a single fluid ejection system or printhead. One or more filters can be situated within the fluid supply manifold and/or entrance to each channel. The filters are designed to collect solidified waste fluid and other contaminants, bubbles, debris, residue and/or deposits or the like that can negatively impact the fluid ejector. 
     U.S. Pat. No. 4,639,748 to Drake et al. discloses an internal, integrated filtering system and fabrication process for an ink jet fluid supply manifold. Small passageways are defined within the fluid supply manifold to deliver ink to a plurality of ink channels. Each of the passageways has smaller cross-sectional flow areas than the ink channels. Therefore, any contaminating particle in the ink that would have passed to the ink channels will be filtered or stopped by the passageways before entering the ink channels. 
     In drop-on-demand thermal ink jet printers, a heating element normally located in the ink channel causes the ink to form bubbles. By applying a voltage across the heating element, such as a heater transducer or resistor, a vapor bubble is formed. The bubbles force the droplets of ink from the nozzle onto the sheet of receiving medium. The channel is then refilled by capillary action from the ink reservoir via the fluid supply manifold. 
     SUMMARY OF INVENTION 
     While ejecting fluid, fluid drawn from the fluid reservoir is directed through the passageways of the fluid supply manifold to each ejector channel. Contaminants, bubbles, debris, and/or residue located in the fluid reservoir can travel to the ejector channels. Filters within the fluid supply manifold and/or design techniques of the fluid supply manifold often trap the contaminants, bubbles, debris, and/or residue before they reach the fluid channels. However, some contaminants, bubbles, debris, and/or residue can reach the inlet of the ejector channels. Just as contaminants, bubbles, debris, residue, and/or deposits can accumulate on the face of the ejector head, thus clogging ejector nozzles and resulting in a deleterious effect on ejection quality, so too does the accumulation of contaminants, bubbles, debris, and/or residue at the inlet of the ejector channels negatively impact the ejection quality. 
     Removing solidified waste fluid and other contaminants, bubbles, debris, residue and/or deposits or the like from the face of the ejector head can be accomplished using any number of available methods, including, but not limited to, using a wiper blade, using a washing unit, and any combination of wiping and washing. While these have proven effective in removing solidified fluid or minute particles from the face of the ejector head, similar methods for clearing ejector channel inlets are not available. As a result, the ejection operation is diminished and slowed because several partial ejection swaths are required to cover the defects. 
     The inventor has determined that ejecting the fluid droplets, such as ink, from the ejector nozzle results in a back pressure within the ejector channel. This back force is directed out the channel inlet, often ejecting any residual fluid remaining in the channel back towards the fluid supply manifold. 
     This invention provides systems and methods for maintaining fluid ejection channels. 
     This invention separately provides systems and methods that remove at least some debris from a channel inlet. 
     This invention separately provides systems and methods for driving a fluid ejection system using a fluid ejection sequence. 
     This invention further provides systems and methods that move to a less harmful position at least some debris that interferes with proper fluid ejection from the ejector channels of the fluid ejection system using the fluid ejection sequence. 
     In various exemplary embodiments of the systems and methods according to this invention, at least some of a plurality of fluid ejectors are fired in a sequential pattern. In various exemplary embodiments, firing a fluid ejector results in a back pressure wave that moves debris, residue, contaminants, deposits or the like back out of the inlet of the fired fluid channel and/or any filter elements positioned on or near the inlet. In various exemplary embodiments, sequentially firing the fluid ejectors causes the back-ejected debris, residue, contaminants, deposits or the like within the fluid supply manifold to move along the direction of the firing sequence. In various exemplary embodiments of the systems and methods according to this invention, the moved contaminants, bubbles, debris, residue and/or deposits or the like can be deposited into locations within the fluid supply manifold that are not associated with operative fluid ejector channels. 
     In various exemplary embodiments of the systems and methods according to this invention, the fluid ejectors are fired in a sequential pattern within blocks of the fluid ejectors. For example, a fluid ejector head with, for example, 120 fluid ejectors can fire 1 out of every 20 fluid ejectors. Therefore, during a first period of the sequence, ejectors at positions  1 ,  21 ,  41 ,  61 ,  81  and  101  fire. Each fluid ejector is fired at least one time, and, in various exemplary embodiments, is fired multiple times, such as, for example, up to 100 times, before the next fluid ejector in the sequence is fired. Then, during a second period of the sequence, the fluid ejectors at positions  2 ,  22 ,  42 ,  62 ,  82 , and  102  fire. Groups of fluid ejectors are fired in this manner until all  120  of the fluid ejectors have fired. This moves any debris, residue, contaminants, deposits or the like within the fluid supply manifold in the direction of firing, i.e., from position 20x+1 to position 20x+20. 
     These and other features and advantages of this 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 partial perspective view of an exemplary fluid ejection system that includes a fluid ejector head with which the systems and methods of the invention are usable; 
     FIG. 2 illustrates one exemplary embodiment of a reservoir, a fluid supply manifold, and the channels of the fluid ejector head of FIG. 1; 
     FIG. 3 is a side cross-sectional view of one exemplary embodiment of a fluid ejector head; 
     FIG. 4 is a rear view of one exemplary embodiment of an ejector channel; 
     FIG. 5 illustrates one exemplary embodiment of an n period of the first exemplary embodiments of the fluid drop ejection sequence according to this invention; 
     FIG. 6 illustrates one exemplary embodiment of an (n+1) th  period of the first exemplary embodiment of the fluid drop ejection sequence according to this invention; 
     FIG. 7 illustrates one exemplary embodiment of an (n+2) th  period of th e first exemplary embodiment of the fluid drop ejection sequence according to this invention; 
     FIG. 8 illustrates one exemplary embodiment of a last period of the first exemplary embodiment of the fluid drop ejection sequence according to this invention; 
     FIG. 9 illustrates one exemplary embodiment of discrete segments of second-to-last periods of a second exemplary embodiment of the fluid drop ejection sequence according to this invention; 
     FIG. 10 illustrates one exemplary embodiment of discrete segments of next-to-last periods of the second exemplary embodiment of the fluid drop ejection sequence according to this invention; 
     FIG. 11 illustrates one exemplary embodiment of discrete segments of last periods of the second exemplary embodiment of the fluid drop ejection sequence according to this invention; and 
     FIG. 12 is a flow chart outlining an exemplary embodiment of a method for fluid ejection sequencing. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Various exemplary embodiments of the systems and methods according to this invention allow fluid ejection systems to be maintained by using firing sequences of the fluid ejectors according to this invention. The mechanisms and techniques used for fluid ejection according to this invention allow moveable contaminants, bubbles, debris, residue and/or deposits or the like within a fluid supply manifold and/or inlet filters to be moved from ejector channel inlets using a back pressure wave resulting from firing of the fluid ejectors. In various exemplary embodiments, contaminants, bubbles, debris, residue and/or deposits or the like are moved within the fluid supply manifold in the direction of the firing sequence of the fluid ejectors. 
     In general, the contaminants, bubbles, debris, residue and/or deposits or the like dislodged by firing the fluid ejectors are moved into less-harmful positions within the fluid supply manifold. Such less harmful positions within the fluid supply manifold can include areas in which no fluid ejectors are connected, areas in which non-operative or dummy fluid ejector channels are connected, areas in which operative but de-selected fluid ejector channels are formed, or the like. It should be appreciated that, in various exemplary fluid ejection systems, fluid ejector channels can be de-selected for any of a variety of reasons. Such reasons include that a particular fluid ejector fails to properly operate, cannot be recovered from a particular failure mode, or the like. Fluid ejectors can also be de-selected based on a particular print algorithm used to select the operative fluid ejectors, such as during printing of partial and/or overlapping swaths. In various exemplary embodiments of the systems and methods of this invention, contaminants, bubbles, debris, residue and/or deposits or the like dislodged by firing the fluid ejectors can be moved or deposited into reservoirs, such as, for example, dummy and/or non-operative ejector channels or de-selected ejector channels that are next to the fluid ejectors or that are at an end of a row of fluid ejectors. 
     The following detailed description of various exemplary embodiments of the fluid ejection systems according to this invention may refer to one specific type of fluid ejection system, an ink jet printer, for the 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 any ink jet printers specifically discussed herein. 
     FIG. 1 is a partial perspective view of an exemplary embodiment ink jet system  100  that includes a fluid ejector head  110  that the systems and methods of the invention are usable with to reduce the effects of contaminants, bubbles, debris, residue and/or deposits or the like on the operation of fluid channels of the fluid ejector head  110 . 
     As shown in FIG. 1, the fluid ejector head  110  is moveable along guide rails  160  in the directions indicated by the arrow  162 . A receiving medium  200  is moveable in the directions indicated by the arrow  210 , which is substantially perpendicular to the directions of movement of the fluid ejector head  110 . 
     In operation, the fluid ejector head  110  is moved along a linear path. The length of the linear path is approximately defined by the sides of the receiving medium  200  so that the fluid ejector head  110  is capable of ejecting fluid along substantially the entire width of the receiving medium  200 . When the fluid ejector head  110  reaches each side of the receiving medium  200 , the receiving medium  200  is incrementally advanced in one of the directions of arrows  210  so that the fluid ejector head  110  is capable of ejecting fluid along substantially the entire length of the receiving medium  200 . 
     The fluid ejector head  110  includes a channel body  130  and an aperture plate  120  at a side of the fluid ejector head  110  that is adjacent to the receiving medium  200 . The aperture plate  120  and the channel body  130  can be disposed adjacent to or substantially adjacent to each other, with the aperture plate  120  being disposed facing the receiving medium  200 . The aperture plate  20  and the channel body  130  can be integral and/or can be connected to each other by any suitable method or structure, such as, for example, by glue, epoxy, welding etc. 
     It should be appreciated, however, the aperture plate  120  and the channel body  130  do not have to be directly connect to each other. For example, other elements can be disposed between the aperture plate  120  and the channel body  130 . Alternatively, the aperture plate  120  and the channel body  130  do not have to be separate elements. 
     FIG. 2 illustrates a top view of one exemplary embodiment of the components that comprise the fluid ejector head  110 . As shown in FIG. 2, in this first exemplary embodiment, the channel body  130  contains a fluid reservoir  140 , a fluid supply manifold  150 , and a plurality of channels  132 , which are substantially aligned with the ejector nozzles of the aperture plate  120  of the fluid ejector head  110 . It should be appreciated that the fluid ejector head  110  may contain any number of channels  132 . 
     The aperture plate  120  can be placed on or over the channel body  130 . As fluid is ejected from the fluid ejectors channels  132  defined in the channel body  130 , the fluid subsequently passes through the nozzles of the aperture plate  120  and onto the receiving medium  200 . 
     It should be appreciated that the plurality of channels  132  of the fluid ejector head  110 , as shown in FIG. 2, may be substantially aligned in the direction of the width of the aperture plate  120 . The ejector channels  132  can be spaced at any desired distance, which may be determined based on a function of the fluid ejection system  100 . Further, it should be appreciated that, as shown in FIG. 2, in various exemplary embodiments, the plurality of channels  132  are formed as a single row. However, in various other exemplary embodiments, two or more rows of the channels  132  may be used, as required, by the fluid ejection system  100 . 
     The fluid reservoir  140  can be any device capable of holding fluid to be used in the fluid ejection system  100 . The fluid supply manifold  150  can be any device capable of receiving fluid from the fluid reservoir  140  and distributing the fluid to the plurality of ejector channels  132 . It should be appreciated that the fluid reservoir  140  and the fluid supply manifold  150 , while depicted separately from each other and from the channel body  130 , may not necessarily be separate and distinct components. Thus, the design, functions and/or operations of the fluid reservoir  140 , the fluid supply manifold  150  and/or the channel body  130  may be carried out by any number of distinct components. 
     FIG. 3 is a side cross-sectional view of one exemplary embodiment of a fluid ejector head  110 . As shown in FIG. 3, the fluid ejector head  110  includes the fluid supply manifold  150 , the channel body  130 , and the aperture plate  120 . The fluid supply manifold  150 , as shown in FIG. 3, includes a fluid inlet  152  and a fluid distribution passage  154 . Fluid from the fluid reservoir  140  enters the fluid distribution passage  154  of the fluid supply manifold  150  via the fluid inlet  152 . In operation, the fluid supply manifold  150  delivers the fluid to a plurality of the ejector channels  132 . In various exemplary embodiments, the fluid ejector head  110  can contain a plurality of fluid supply manifolds  150  providing fluid to a plurality of distinct sets of the ejector channels  132 . 
     Alternatively, the fluid ejector head  110  can include a fluid supply manifold  150  in which the fluid distribution passage is divided into distinct portions that are not necessarily in fluid communication with each other. In this case, each such distinct portion may have its own fluid inlet  152 . Each distinct portion of the fluid distribution passage  154  supplies fluid primarily to the associated set of the plurality of ejector channels  132 . It should be appreciated that the design of the fluid ejector head  110 , including the fluid supply manifold  150 , ejector channels  132 , and aperture plate  120  will be obvious and predictable to those skilled in the art. 
     FIG. 4 is a cross-sectional view taken along the line  4 — 4  of FIG.  3 . FIG. 3 depicts the channel inlet  134  from the fluid distribution passage  154  to the ejector channel  132 . The channel inlet  134  allows fluid from the fluid supply manifold  150  to enter into the ejector channel  132 . In various exemplary embodiments, the channel inlet  134  is smaller than the cross-sectional flow area of the ejector channel  132 . It should be appreciated that the particular size and shape of the channel inlet  134  will be obvious and predictable to those skilled in the art. 
     Although not depicted, it should be further appreciated that the fluid supply manifold  150  can employ various filtering techniques, including, but not limited to, filters and unique fluid supply manifold passageway designs to contain and/or trap contaminants, bubbles, debris, and/or residue within the fluid supply manifold  150 . Such contaminants, bubbles, debris, and/or residue not trapped and/or contained within the fluid supply manifold  150  can accumulate at the channel inlet  134  and/or enter into the channel  132 . When the debris, residue, contaminants, deposits or the like collect at or within the channel inlet  134 , the cross-sectional flow area of the channel inlet  134  can become significantly reduced. This reduces the amount of fluid that can flow into the fluid channel  132  between a last firing and a next firing of that channel  132 . A partially-filled fluid channel  132  will generally not eject a drop of fluid correctly. Additionally, as the fluid acts to cool the resistive heater of a thermal fluid ejector, the resistive heater can overheat and fail due to such improper filling. 
     If the debris, residue, contaminants, deposits or the like collect in the fluid channel  132  itself, these same problems can occur. Additionally the debris, residue, contaminants, deposits or the like in the ejector channel  132  can become lodged in the nozzle or can decompose, coat the resistive heater of a thermal system or otherwise detrimentally affect the fluid channel  132  and/or the nozzle. 
     FIGS. 5-8 illustrate a number of periods of a first exemplary embodiment of the ejector firing sequence according to this invention. As shown in FIGS. 5-8, the fluid supply manifold  150 , having a number of end walls  156 , provides the fluid to the plurality of ejector channels  132 . In FIGS. 5-8, fluid flows in direction  136  through a plurality of nozzles. As shown in FIG. 5, during an n th  period of the fluid drop ejection sequence, a fluid drop  138  is ejected from the n th  channel  132 . It should be appreciated that, in this first exemplary embodiment, and as well as any other exemplary embodiment according to this invention, each period can include one or more firings of the current ejector channel  132 . Thus, in various exemplary embodiments, a large number of firings, such as 100 firings, of each ejector channel  132  can occur during each period. 
     During operation, particles  170  can collect and/or form on, in and/or near the channel inlet  134  and can adversely affect the fluid drop  138  exiting the ejector channel  132 . These adverse effects include, but are not limited to, restricting and/or blocking the channel inlets  134 . The particles  170  can be any substance that is capable of obstructing the channel inlet  134 , including solidified fluid, dust, and the like. The particles  170  can also be bubbles of air or the like that are present in the fluid. In general, the particles  170  are anything other than fluid that can freely flow through the channel inlet  134 . 
     When fluid ejects from the ejector channels  132 , a back pressure pulse  139  is directed backwards from the channel inlet  134  into the fluid supply manifold  150 , often ejecting any residual fluid remaining in the ejector channel  132  back towards the fluid supply manifold  150 . The resulting back pressure pulses  139  tend to dislodge the particles  170  in a direction  172  towards and possible pass the adjacent (n+1) th  ejector channel  132 . In various exemplary embodiments, the force of the back pressure pulses  139  dislodges the particles  170 . However, it should be appreciated that some other physical process that occurs in response to the back pressure pulses  139  being directed back into the fluid supply manifold  150  may be responsible for dislodging the particles.  170 . 
     Although the particles  170  are depicted as dislodging in the direction  172 , it should be appreciated that the direction that any given particle  170  moves is predicated on its position on and/or around the n th  channel inlet  134  and/or the force and/or angle with which any given back pressure pulse  139  impacts that particular particle  170 . Subsequently, a dislodged particle  170  can land on part or portion of other channel inlets  134 , including, but not limited to that space between the ejector channels  132 . For example, in FIG. 5, the particles  170  can be dislodged in the direction  172  towards the n+1 th  ejector channel  132  but could land between the n th  ejector channel  132  and the n+1 th  ejector channel  132 . 
     Accordingly, in various exemplary embodiments of the firing sequence according to this invention, each ejector channel  132  is fired a plurality of times, such as, for example, 100 times. In various exemplary embodiments, it is believed that, each time a given ejector channel  132  is fired, the resulting back pressure pulse  139  further dislodges additional particles  170  and/or further moves of the particles  170  away from that ejector channel  132 . In various exemplary embodiments, the size of the back pressure pulse  139  and the number of times each ejector channel  132  is fired combines move the particles  170  from around the n th  ejector channel  132  to at least more than halfway past the next n+1 th  ejector channel  132 . 
     This will tend to place those particles in a position such that, during the (n+1) th  period, when that next n+1 th  ejector channel  132  is fired, those particles  170  will tend to move towards the next n+2 th  ejector channel  132  and not back toward the n th  ejector channel  132 . This will also tend, during the n th  period, to move any particles  170  near the channel inlet  134  of the n+1 th  ejector channel  132  that are relatively closer to the n th  ejector channel  132  than to the n+2 th  ejector channel  132  toward the n+2 th  ejector channel  132 . Thus, those particles  170  will also tend to be placed on a position such that, when the n+1 th  ejector channel  132  is fired during those (n+1) th  period, those particles  170  will also tend to move towards the n+2 th  ejector channel  132  instead of back towards the n th  ejector channel  132 . 
     It should be appreciated that the number of pulses to be fired during each period can be predetermined, could have been empirically determined during design, development and/or manufacturing of the fluid ejector head as that number that is sufficient to adequately move the particles  170 , or could be dynamically determined during operation based on the degree of adverse printing effects or the like. This dynamic determination can be performed by the user or by a controller (not shown). 
     FIG. 6 illustrates an exemplary embodiment of the (n+1) th  period of the first exemplary embodiment of the fluid ejection sequence. After the n th  ejector channel  132  depicted in FIG. 5 has been fired the one or more times, the particles  170  have moved from the positions shown in FIG. 5 towards the positions shown in FIG.  6 . FIG. 6 shows the (n+1) th  ejector channel  132  ejecting a drop  138 . The resulting back pressure pulse  139  dislodges or further moves the particles  170  in the direction  172 . The particles  170  will generally tend to include not only those particles dislodged from previous ejector channels  132 , but also additional particles  170  dislodged from the n+1 th  channel  132 . 
     Also as discussed above, the direction that the particles  170  moves in FIG. 6 is predicated on its position on, in and/or around the channel inlet  134  and/or the force and/or angle with which the back pressure pulse  139  impacts the particles  170 . Subsequently, the particles  170  can land on part or portion of other channel inlets  134 , including, but not limited to that space between the ejector channel  132 . 
     FIG. 7 illustrates an exemplary embodiment of the (n+2) th  period of the first exemplary embodiment of the fluid ejection sequence. After the (n+1) th  ejector channel  132  depicted in FIG. 6 has been fired the one or times, the particles  170  have moved from the positions shown in FIG. 6 towards the positions shown in FIG.  7 . FIG. 7 shows the (n+2) th  ejector channel  132  ejecting a drop  138 . The resulting back pressure pulse  139  dislodges or further moves the particles  170  in the direction  172 . The particles  170  will generally tend to include not only those particles dislodged from the previous ejector channels  132 , but also additional particles  170  dislodged from (n+2) th  ejector channel  132 . 
     Also as discussed above, the direction that the particles  170  moves in FIG. 7 is predicated on its position on, in, and/or around the channel inlet  134  and/or the force and/or angle with which the back pressure pulse  139  impacts the particles  170 . Subsequently, the particles  170  can land on part or portion of other channel inlets  134 , including, but not limited to that space between the ejector channels  132 . 
     FIG. 8 illustrates an exemplary embodiment of the m th  or last period of the first exemplary embodiment of the fluid ejection sequence. After the (n+2) th  ejector channel  132  depicted in FIG. 7, and any intervening ejection channel(s) have been fired the one or more times, the particles  170  have moved from the positions shown in FIG. 7 towards the positions shown in FIG.  8 . FIG. 8 shows the m th  ejector channel  132  ejecting a drop  138 . The resulting back pressure pulse  139  dislodges or further moves the particles  170  in the direction  172 . The particles  170  will generally tend to include not only those particles dislodged from all of the previous ejector channels  132 , but also additional particles  170  dislodged from m th  ejector channel  132 . 
     Also as discussed above, the direction that the particles  170  moves in FIG. 8 is predicated on its position on, in, and/or around the channel inlet  134  and/or the force and/or angle with which the back pressure pulse  139  impacts the particles  170 . Subsequently, the particles  170  can land on part or portion of other channel inlets  134 , including, but not limited to that space between the ejector channels  132 . 
     As shown in FIG. 8, non-operative ejector channels  180 , or a space where an ejector channel  132  could have been formed but has not been, are situated after the m th  or last ejector channel  132 . Although three non-operative ejector channels  180  are shown, it should be appreciated that any number of non-operative ejector channels  180 , such as, for example, dummy ejector channels, failed ejector channels and/or de-selected ejector channels or size of the space can be used. As shown in FIG. 8, the dislodged particles  170  accumulate in and/or around the non-operative ejector channels  180 . 
     It should be appreciated that the ejector channels  132  shown in FIGS. 5-8 represent any segment of an array of the fluid ejector channels  132 . For example, the ejector channels  132  in FIGS. 5-8 can be at the beginning, the middle, or end of an array of ejector channels  132 . 
     It should be further appreciated that, though it is not depicted, the sequential fluid ejection illustrated in FIGS. 5-7 with respect to the n th , (n+1) th , and (n+2) th  ejector channels  132 , respectively, continues with the sequential firing of the remaining ejector channels  132  until all the ejector channels  132  in a given array have fired. Any dislodged particles  170  that move along the array of ejector channels  132  as a result of the back pressure pulse  139  generated by the sequential firing can be dislodged and/or moved by the m th  or last ejector channel  132  that fires into an area  182  that collects such moveable contaminants. Any particle  170  dislodged or removed from the channel inlets  134  during the sequential firing process and deposited onto the area  182  away from the operative ejector channels  132 , such as, for example, a non-operative channel  180 . 
     FIGS. 9-11 show a number of consecutive periods of a second exemplary embodiment of the ejector firing sequence and a second exemplary embodiment of the ejector body  130  and the fluid supply manifold  150  according to this invention. In FIGS. 9-11, in this second exemplary embodiment of the firing sequence, the ejector channels  132  within the fluid ejector body  130  are, at least operationally, divided into discrete sections separate from the others by various ones of the end, or partition, walls  156 . In the specific embodiment shown in FIGS. 9-11, the ejector channels  132  are divided, at least operationally, into sections of 40 ejector channels  132 . Although the ejector channels  132  in FIGS. 9-11 are divided at least operationally into sections of 40 ejector channels  132 , it should be appreciated that the array of ejector channels  132  can be divided into at least operational sections of any desired number, for example, sections of 10 channels, 20 channels, or 30 channels. It should be further appreciated that the ejector channels  132  shown in FIGS. 9-10 could be depicting the beginning, middle, or end sections of a row of channels. 
     In FIGS. 9-11, fluid flows in the direction  136  through the plurality of ejector channels  132 , ejecting drops  138  from the ejector channels  132 . As shown in FIGS. 9-11, zero, one or more non-operative channels  180  of the area  182  are associated with each at least operationally-associated set of 40 operative ejector channels  132 . Although only one non-operative channel  180  is shown associated with each at least operationally-associated set of 40 operative ejector channels  132 , it should be appreciated that any number of non-operative channels  180 , or a space of any appropriate size, can be associated with each at least operationally-associated set of operative ejector channels  132  in the area  182 . 
     In various exemplary embodiments, sequentially firing the fluid drops  138  through the ejector channels  132  can be enhanced by using a regular firing pattern. For example, by firing drops simultaneously through certain ones of the ejector channels  132  using a pattern, such as a pattern where one out of every 40 ejector channels  132  is fired, the resulting back pressure pulse  139  can move the contaminants, bubbles, debris, residue and/or deposits  170  or the like that has collected in and/or around the channel inlet  134  in the direction of the firing sequence for more than a single ejector channel at a time. 
     As shown in FIG. 9, fluid is ejected at the same time out of the ejector channels  132  at positions n, n+40, n+80, n+120 and for a given number of drops. Any contaminants, bubbles, debris, residue and/or deposits  170  or the like are moved from the channel inlet  134  of the n+40x channels  132  in the direction  172 . In the next period of the firing sequence, as depicted in FIG. 10, fluid is ejected at the same time from the next set of the ejector channels  132  at the positions n+1, n+41, n+81, and n+121, etc. and for a given number of drops. The sequential firing sequence continues as depicted in FIG. 11 with drops  138  being ejected through the next set of the ejector channels  132  at the positions n+2, n+42, n+82, and n+122. Eventually, as a result of the back pressure pulses  139  generated by sequentially firing the drops of fluid through the ejector channels  132 , any contaminants, bubbles, debris, residue and/or deposits  170  or the like end up in the area  182 . 
     It should be appreciated that any number of drops  138  can be ejected by each of the ejector channels  132 . Thus, for example, in various exemplary embodiments, each ejector channel  132  ejects the same number of drops  138 . In contrast, in various other exemplary embodiments, each ejector channel  132  ejects a particular number of drops  138 , which, in general, will be different from at least one other one of the ejector channels  132 . 
     It should also be appreciated that the fired ejector channels  132 , although shown immediately adjacent to each other in FIGS. 1-11, could be spaced from each other by one or more intervening operative or non-operative ejector channels  132 . Thus, if the particles  170  dislodged by the back pressure pulses  139  are displaced by two or more channel separations, it may be advantageous to skip one or more channels between a pair of driven ejector channels  132 . 
     FIG. 12 is a flowchart outlining one exemplary embodiment of a method for ejecting fluid in a sequence according to this invention. As shown in FIG. 12, operation of the method begins in step S 100  and continues to step S 110 , where the first set of channels to be fired is selected. Then, in step S 120 , the current set of channels is fired a given number of times to move any contaminants, bubbles, debris, residue and/or deposits back from the channel inlet into the fluid supply fluid supply manifold toward at least a next channel. Next, in step S 130 , a determination is made whether there is an additional set of channels that need to be fired. If no additional set of channels needs to be fired, operation continues to step S 140 . Otherwise, operation jumps to step S 150 . 
     In step S 140 , the next set of nozzles are selected as the current set to be fired. Operation then jumps back to step S 120 . In contrast, in step S 150 , operation of the method ends. 
     It should be appreciated that, in various exemplary embodiments, the method outlined above is performed during a maintenance operation to move any of the contaminants, bubbles, debris, residue, and/or deposits that may have collected in and/or around the channel inlet  134  to less-harmful positions. Such a maintenance operation can be performed as part of a regular overall maintenance operation or can be performed when desired by the operator. It should further be appreciated that the method outlined above could be performed during normal printing operations. In particular, the method outlined above could be performed when an analysis of the print data indicates that the desired sequence of firing the fluid ejectors at least the desired number of times can be performed at the same time that the fluid is ejected to form the desired pattern of ejected fluid on the receiving medium. 
     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