Patent Description:
The present disclosure relates to nozzle health for ink jet printers.

Ink jet printers, such as piezoelectric ink jet printers, have a number of uses, such as, for example, using ink to print on paper as well as substrate surfaces, such as plastic, used for identification cards (e.g., government-issued licenses, workplace identification cards, or the like). During routine operation of an ink jet printer it is common for performance of the ink jet nozzles to be reduced over time (e.g., by becoming clogged) which, in turn, reduces print quality. <CIT> describes a method of maintaining nozzles in a print-ready condition. <CIT> describes an image forming apparatus with a recording head for ejecting liquid droplets.

Described herein are systems and methods for improving ink jet nozzle health and printing reliability of an ink jet printer. A system may generally include a processor and memory, including instructions stored thereon which, when executed by the processor, cause the processor to monitor whether a triggering event has occurred. In an example, the triggering event may be an elapsed period of time. The elapsed period of time may be an amount of time the printer has been powered off, an amount of time the printer has remained idle, an amount of time the printer has been in a low-power mode, or an amount of time since an ink cartridge has been manually agitated, shaken, or the like.

The period of time may be determined by the processor (e.g., <NUM> hours of idle time), or manually selected by a user.

When the processor detects that the triggering event has occurred, the processor may cause at least a portion of ink contained in a header tank, the header tank included as a part, component, or the like, of a scan head, to be pumped, moved, or the like, in a direction from the header tank toward the ink cartridge, for example, through one or more tubes connecting the ink cartridges to the header tank. The system may circulate the ink from the direction toward the ink cartridge back into the header tank. The header tank may include a level sensor that the system may use to monitor a level of ink in the header tank (e.g., to prevent the header tank from overfilling as ink is circulated back into it). The system may further agitate the scan head by causing the scan head to move in at least one of: a left-to-right direction, a right-to-left direction, a back-to-front direction, or front-to-back direction, along an x-y gantry.

The system may also, optionally, apply a "tickle pulse" to the print head to further mix the ink to be ejected from the print head. This may include the processor causing a waveform (e.g., a current, voltage, or pulsed voltage in which the pulses are a controlled voltage stepped upward or downward) to be applied to the print head that is not strong enough to eject a drop of ink from a nozzle in the print head, but will mix the ink within the print head.

A method for improving ink jet nozzle health and printing reliability of the ink jet printer may include, moving a scan head to a maintenance station. The maintenance station may include a purge cap and a wiper ( e.g., a printhead ink purging reservoir and a separate printhead nozzle plate wiper), and the scan head may include at least a header tank, and a print head operatively connected to the header tank. The print head may include a nozzle plate, the nozzle plate including at least one row of nozzles containing a plurality of nozzles. The method may further include creating at least a partial seal between the purge cap and at least one of: a particular nozzle of the plurality of nozzles, the row of nozzles, the nozzle plate, or the print head. The method may also include performing a reverse purge of at least one of: a particular nozzle of the plurality of nozzles, the row of nozzles, the nozzle plate, or the print head. The reverse purging may include applying a positive pressure using the purge cap by reversing a direction of a vacuum pump (e.g., a peristaltic pump). The reverse purging may cause at least a portion of ink located in at least one nozzle of the plurality of nozzles to be pushed, moved, or the like, through at least one nozzle in a direction toward the header tank. The direction of the vacuum pump may optionally be reversed again (e.g., to turn, operate, move, rotate, or the like, in a forward direction) causing the vacuum pump, using the purge cap, to apply a negative pressure to suck ink, clogs, obstructions, or the like, through at least one nozzle of the plurality of nozzles.

A method may further include ejecting an amount of ink from the print head and activating the wiper to move across the nozzle plate simultaneously or substantially simultaneously with the ejecting of the amount of ink. The amount of ink may be cleaned from the wiper by rotating the wiper about an axle, causing the amount of ink to enter a waste deposit located below the wiper and the axle. The amount of ink (e.g., waste ink) may then be removed from the waste deposit using the vacuum pump, or a second vacuum pump.

A method may also include printing a first image onto a first substrate using the print head. The print head may begin printing the first image from a first starting position above the first substrate. During the printing of the first image, particular ones of the plurality of nozzles included on the print head may be used, while other particular ones of the plurality of nozzles may not be used. The method may further include randomizing a second starting position relative to the first starting position.

In an example, the method may then include printing a second image onto a second substrate using the print head, wherein the print head begins the printing of the second image from the second starting position. In an example, at least a portion of the first image may be identical to at least a portion of the second image. Similarly, the first substrate may be substantially the same size as the second substrate. When printing the second image, at least one nozzle of the particular ones of the plurality of nozzles used in printing the first image may not be used. Further, when printing the second image, at least one of the other particular ones of the plurality of nozzles not used when printing the first image may be used. In short, different nozzles on the print head may be used, utilized, or the like, when printing the first image than are used/utilized when printing the second image, to prevent nozzles from remaining dormant or unused for an extended period of time.

ink jet printing with pigmented ink, especially with white ink, can be challenging because the pigment in the ink may have relatively large particles. Such inks include, for example, inks containing titanium-dioxide pigment. Large particles can settle out of solution and lead to clogged nozzles (e.g., printhead nozzles, such as piezoelectric printhead nozzles) or reduce the opacity of the ink. Further, when printing certain images, some of the ink jet nozzles may not be utilized during the printing, depending on, for example, the size, shape, and/or location of the image to be printed on a substrate. When nozzles are left idle for an extended period of time, they may not stay primed, leading to poor jetting characteristics due to pigment settling. Additionally, when the same print job (e.g., printing essentially the same image or series of images on a plurality of similar substrates, such as plastic identification cards, each printing to a substrate referred to herein as a "print operation" within the print job) is sent to the printer many times, it can often result in only certain nozzles being used, which can then lead to poor print quality when a new or different print job or new or different image is printed. The disclosed systems and methods provide efficient, low-cost solutions to such issues without the need of costly equipment.

Particularly, described herein are systems and methods for improving inkjet nozzle health and printing reliability. <FIG> illustrates an example of the interior <NUM> of a printer employing systems and methods described herein. Generally, the interior <NUM> of the printer may include a print carriage configured to hold one or more ink cartridges. This may include cartridges containing pigmented ink such as black, white, cyan, yellow, magenta, or the like, or unpigmented varnish (e.g., a clear coat). Ink may be fed/sent/moved, or the like, from the ink cartridges via one or more tubes, or one or more series of tubes, located in the interior <NUM> of the printer, to one or more header tanks. The header tanks may be a component, part, or the like, of a scan assembly/scan head which may also include print heads from which ink is ejected, dropped, deposited, or the like. The scan assembly may be movable in multiple directions (e.g., horizontally/left-to-right/right-to-left, and back and forth) along a gantry, rails, or the like, to allow for printing over an entire surface of a substrate. The scan assembly may also be movable over a maintenance station, configured to clean the print heads, or nozzles on the print head nozzle plate (e.g., clearing clogs, removing excess ink, or the like).

In a specific example illustrated in <FIG>, the interior <NUM> of the printer may include a scan head <NUM> that moves along an x-y gantry. The gantry may include a x-direction gantry/scan rail <NUM> and at least one y-direction gantry/scan rail <NUM>. The x-direction gantry <NUM> may allow the scan head <NUM> to move in a substantially sideways/horizontal direction (e.g., left-to-right or right-to-left), or more generally, along a first axis (e.g., an x-axis). The y-direction gantry <NUM> may allow the scan head <NUM> to move substantially perpendicular to the x-direction gantry <NUM> (e.g., forward and backward, front-to-back, back-to-front, or the like), or more generally, along a second axis (e.g., a y-axis). This may allow the scan head <NUM> to print with complete coverage over a card surface <NUM> without having to reposition the card surface <NUM>.

In an example, the interior <NUM> may further include a print cartridge carriage <NUM> configured to hold, contain, or the like, one or more print/ink cartridges <NUM> containing ink. Each ink cartridge, such as ink cartridge <NUM>, may be connected to a header tank (as shown and described in <FIG> below) included within the scan head <NUM>, via a tube <NUM> (e.g., a hose, tubing, or any similar flexible material capable of containing and moving ink), that may be efficiently located (e.g., run along, fed, or the like) along, near, through, proximate to (e.g., behind), or the like, a flexible or semi-flexible chain <NUM> or other type of linking mechanism located along a side and rear of the interior <NUM> and capable of moving with or otherwise accommodating movement of the scan head <NUM>. The tube <NUM> may connect to the ink cartridge <NUM> in an area below the ink cartridge <NUM> or the print cartridge carriage <NUM> and connect to a pump, such as a peristaltic pump shown and described in <FIG> below, or other similar pump to move the ink through the tube <NUM>. The tube <NUM> may be connected to the scan head <NUM> by locating the tube <NUM> along the chain <NUM> which runs to the scan head <NUM>. It is understood that there may be more than one tube or series of tubes, such as tube <NUM>, as needed, and that the tubes may be located in the interior <NUM> along any suitable path, route, or the like, from the ink cartridges, such as ink cartridge <NUM>, or the print cartridge carriage <NUM> to the header tanks. For example, the system may contain one tube per ink cartridge feeding to one header tank (as described below) or there may be multiple tubes per ink cartridge feeding ink to multiple header tanks, or multiple chambers of a single header tank.

The interior <NUM> may also include a maintenance station <NUM>, as described below in <FIG>, configured to clean, clear, or otherwise maintain the print heads located on the bottom of the scan head <NUM>. The maintenance station <NUM>, may include a purge cap <NUM> and a wiper <NUM> as discussed below, configured to clean the print heads (discussed below in <FIG>).

<FIG> illustrates an example of header tanks connected to print heads. The scan head may contain one or more header tanks which are fed ink from the ink cartridges through the tubing, such as tube <NUM>, as described above for <FIG>. The header tanks may, in turn, contain one or more chambers into which the ink or varnish from the ink cartridges is contained. For example, a header tank may have a single chamber containing a pigmented ink, or, alternatively, two or more chambers (e.g., dual chambers). In such an example, one of the chambers may contain a pigmented ink while the other chamber contains a different colored pigmented ink. Or, alternatively, one or more chambers may contain a varnish/clear coat.

In an example illustrated in <FIG>, the scan head <NUM> may include header tanks <NUM>, <NUM>, <NUM> which contain ink directed from corresponding ink cartridges, such as ink cartridge <NUM>, via tubing, such as tube <NUM>, located along the chain <NUM>, as described above for <FIG>. In an example, at least a portion of the chain <NUM> may be located behind the scan head <NUM> and allows tubing, such as tube <NUM> from the ink cartridges, such as ink cartridge <NUM>, to connect to a corresponding one of the header tanks, such as header tanks <NUM>, <NUM>, <NUM>, located in scan head <NUM>. In an example, the header tanks <NUM>, <NUM>, <NUM> may be dual chamber tanks, which feed ink to print heads, and nozzles located on the print heads (as described below), which are located below the header tanks <NUM>, <NUM>, <NUM>.

<FIG> illustrates an example of print heads connected to header tanks, such as header tanks <NUM>, <NUM>, <NUM>. The header tanks may be operatively connected to print heads. In an example, a single header tank may be connected to a corresponding one of the print heads, and feed ink from the chamber or chambers of the header tank (in the example of a dual or multi chamber tank) to the print heads through nozzles located on a nozzle plate on the bottom of the print heads (as described below).

In an example illustrated in <FIG>, print heads <NUM>, <NUM>, <NUM>, may be located on a bottom/lower surface of the scan head <NUM>, and connected to the header tanks <NUM>, <NUM>, <NUM>. In an example, there may be as many print heads <NUM>, <NUM>, <NUM>, as there are header tanks <NUM>, <NUM>, <NUM>, with one of the header tanks <NUM>, <NUM>, <NUM>, corresponding to (e.g., be connected to and feed/send/provide ink to) one of the print heads <NUM>, <NUM>, <NUM>, which in turn may eject/spit/drop ink through one or more print nozzles (shown and described in <FIG> below). For example, header tank <NUM> may correspond to print head <NUM>, while header tank <NUM> may correspond to print head <NUM>, and header tank <NUM> may correspond to print head <NUM>. Alternatively, the system may include multiple single-channel header tanks, one or more of which may be operatively connected to one or more print heads (e.g., six header tanks connected to some combination of three or more print heads).

<FIG> illustrates an example of a partial nozzle plate <NUM> of a print head, such as print heads <NUM>, <NUM>, or <NUM> including a plurality of print nozzles. The system may include multiple nozzle plates (e.g., one or more nozzle plates per print head). The nozzle plates of the print heads may contain one or more rows of nozzles through which ink from the chambers of the header tanks, such as header tanks <NUM>, <NUM>, or <NUM> is ejected, dropped, or the like, into the interior <NUM> such as onto card surface <NUM>. In an example as described above in which multiple single-channel header tanks are connected to some combination of print heads, multiple header tanks (e.g., two header tanks) may be operatively connected to a single print head such that ink from one header tank is ejected from a particular first row of nozzles on the nozzle plate, and ink from another header tank is ejected from the other of the row of nozzles (e.g., a second row of nozzles) on the nozzle plate. Alternatively, a single header tank may be connected such that ink from that tank is only ejected from particular nozzles in a row of nozzles on the nozzle plate. The present disclosure is not to be limited by any particular configuration or connection between the header tanks, print heads, and nozzles.

In the specific example of <FIG>, each print head <NUM>, <NUM>, or <NUM> may include a nozzle plate, such as nozzle plate <NUM> which may be formed from a piezoelectric or another similar material. The nozzle plate <NUM> may, in turn, include a first row of print nozzles <NUM> and a second row of print nozzles <NUM>, each row including a plurality of individual nozzles. Each individual nozzle in the rows of nozzles <NUM> and <NUM> is configured to eject, drop, spit, or the like, ink from a particular one of the header tanks, such as header tanks <NUM>, <NUM>, or <NUM> connected to a particular one of the print heads, such as print heads <NUM>, <NUM>, or <NUM>.

<FIG> illustrates an example of a maintenance station <NUM> including a purge cap <NUM> and wiper <NUM>. The maintenance station may be located below the scan head <NUM>, and may be used to clean the print heads and/or the nozzle plate utilizing a vacuum pump and/or a wiper to remove clogs or other similar obstructions in the nozzles, or to wipe, remove, or the like, ink from the print heads. For example, the system may employ a "spitting while wiping" process (described in detail below) to clean the print heads <NUM>, <NUM>, <NUM>, and the nozzle plate <NUM> corresponding to the particular print head <NUM>, <NUM>, or <NUM>.

In the example illustrated in <FIG>, the maintenance station <NUM> may be located or included in/within the interior <NUM> of the printer, such as below the scan head <NUM>. In an example, the maintenance station may be fixed, stationary, or the like, below the scan head <NUM>. In an example, the scan head <NUM> may be movable to the maintenance station <NUM> (e.g., by moving/lowering the scan head downward). Moving the scan head to the maintenance station may place one or more of the print heads, or the nozzle plates of the print heads, in a position so as to be cleaned (e.g., one or more nozzles to be cleared of a clog or other similar obstruction). Additionally, or alternatively, the maintenance station may be configured to move to the scan head <NUM> (e.g., upward), to place the maintenance station into a position to clean the print heads, nozzle plate, or nozzles, as described above.

In an example, an amount of ink may be ejected from a print head, such as print head <NUM>, <NUM>, or <NUM>, (e.g., from one or more of the nozzles in the row of nozzles <NUM> or <NUM>), e.g., onto the nozzle plate <NUM>. A wiper <NUM> is located on, near, or within the maintenance station <NUM> and may be configured to move (e.g., laterally, left-to-right, right-to-left, side-to-side, or the like) below the print heads <NUM>, <NUM>, <NUM> and each of the print heads' corresponding nozzle plate, such as nozzle plate <NUM>. Additionally, or alternatively, the wiper <NUM> may rotate about/around an axle <NUM>. The wiper <NUM> may be formed from a flexible material such as rubber or another similar material. The wiper <NUM> may be formed in the shape of a blade with at least an edge configured to contact the surface of the nozzle plate <NUM> and wipe against the nozzle plate as the wiper is moved laterally and/or is rotated, as described above. The wiper <NUM> may, simultaneously or substantially simultaneously with the ejection of the ink from at least one nozzle in the row of nozzles <NUM>, <NUM> onto the nozzle plate <NUM>, wipe the nozzle plate <NUM> clean of ink.

By simultaneously or substantially simultaneously wiping the ink from the nozzle plate <NUM> with the wiper <NUM> as the ink is ejected from at least one nozzle in the rows of nozzles <NUM>, <NUM>, ejected ink may be prevented from being pushed back into the nozzles and mixing with "clean" ink, or being re-ejected, re-dropped, re-spit, or the like from, the print heads <NUM>, <NUM>, or <NUM> during a subsequent print operation or print job. In an example, the wiper <NUM> may rotate about the axle <NUM> which may be a cylindrical rod connected, attached, or the like, to the wiper <NUM> which allows the wiper <NUM> to additionally wipe against a piece of material <NUM> (e.g., plastic, metal, or the like) allowing ink to be cleared from the wiper <NUM>. Waste ink wiped from the nozzles, nozzle plate, or print heads may collect on the surface of the wiper <NUM>, as the wiper moves below the print heads/nozzles/nozzle plates, and when the wiper <NUM> is rotated about the axle <NUM>, the waste ink may be removed (e.g., scraped off) from the wiper as it makes contact with the material <NUM>. Then, as (e.g., immediately after or at substantially the same time as) the waste ink is removed from the wiper <NUM> it may fall or otherwise caused to be moved below the wiper <NUM> and axle <NUM>, into a waste deposit <NUM>, which may be a well, depression, opening, compartment, or the like, at which point, the waste ink may be removed from the maintenance station <NUM>, such as by being sucked/vacuumed, or the like, from the maintenance station <NUM> using a vacuum pump, such as <NUM> as shown and described in <FIG>, below.

Returning to <FIG>, the maintenance station <NUM> may also include a purge cap <NUM> which may be used as a part of a reverse purging process in conjunction with a vacuum pump such as pump <NUM> shown in <FIG>. The purge cap <NUM> may be located below the print heads as the print heads/scan head moves to the maintenance station <NUM> as described above. In some examples, the purge cap <NUM>, may additionally or alternatively move to the scan head <NUM> (e.g., move with the maintenance station to the scan head), so as to locate the purge cap <NUM> below one or more nozzles in one of the row of nozzles <NUM>, <NUM>, on the nozzle plate <NUM>. The nozzles <NUM>, <NUM>, or the nozzle plate <NUM>, may be operably positioned over the purge cap <NUM> such that at least a partial seal may be made around one or more nozzle, an entire row of nozzles, such as <NUM>, <NUM>, or an entire print head, such as <NUM>, <NUM>, or <NUM>.

Once the purge cap <NUM> is in place below the nozzles/nozzle plate/print head, the vacuum pump <NUM> may be reversed so as to apply a positive pressure through the purge cap <NUM> causing ink, a clog, or an obstruction in one or more nozzles of the rows of nozzles <NUM>, <NUM> to be pushed into the nozzle (e.g., in a direction toward the header tanks <NUM>, <NUM>, <NUM>), in a "reverse purge" process. Optionally, the vacuum pump may be reversed again to suck the clog or obstruction out of the nozzle, or a technique such as the "spitting while wiping" technique described above, may be employed additionally or alternatively to clean, clear, or the like, the rows of nozzles <NUM>, <NUM> after the reverse purge process is performed. In an example, the vacuum pump <NUM> may be used to perform the "reverse purge" process on the print head or nozzles, with any "normal purge" process (e.g., sucking/vacuuming a clog out of the nozzle) either before or after the reverse purge, being optional.

<FIG> illustrates an example of a vacuum pump <NUM> employed by the system. This may include, for example, one or more peristaltic pumps, or any other suitable pump capable of moving ink through a tube, such as tube <NUM>, or a series of tubes (e.g., from the ink cartridges to the header tanks) or creating a positive pressure at the purge cap <NUM> to employ the reverse purging process, as described above. In an example, the vacuum pump <NUM> may include a rotor <NUM> which may include one or more lobes <NUM> capable of compressing a tube <NUM> as the rotor <NUM> rotates, turns, or the like. The lobes <NUM> may include or be replaced by one or more rollers, shoes, wipers, or the like. As the rotor <NUM> turns, the part of the tube <NUM> under compression is occluded (e.g., pinched closed), forcing a fluid to be moved through the tube <NUM>.

In an example the system may utilize, employ, include, or the like, one or more vacuum pumps <NUM> attached to various components such as the ink cartridge <NUM>, the scan head <NUM>, the maintenance station <NUM>, or any similar component. The pump <NUM> may be configured to move ink through tubing, hoses, or the like, connected to various components, or may be configured to remove (e.g., through suction) waste ink from the maintenance station <NUM>.

<FIG> illustrates an example of a method for improving ink jet nozzle health and printing reliability, and particularly a method for automatically agitating the ink between the ink cartridges and the header tanks, also referred to herein as "auto agitation. " Step <NUM> may include monitoring an elapsed time period or other triggering event. The elapsed time period may be the amount of time since a prior auto agitation routine has been run. In an example, the elapsed time period may be the period of time since a ink cartridge such as <NUM> has been automatically or manually agitated, shaken, or the like (e.g., the amount of time since a ink cartridge such as <NUM> has been removed from the print cartridge carriage <NUM> and shaken, vibrated, or the like, to cause the ink in the cartridge <NUM> to mix). This may be done by, for example, shaking the cartridge <NUM> by hand or using a mechanical stirrer. In an example, the elapsed time (e.g., eight hours or other suitable time) may be set by a user of the printer or may be, e.g., a default time period set by the manufacturer. For example, the manufacturer setting may recommend that an ink cartridge such as ink cartridge <NUM> be manually agitated or otherwise shaken every eight hours, but the user may set a lower amount of time (e.g., every six hours or other suitable time). In an example, the elapsed time may correspond to the amount of time the printer is idle, turned off, or in a low-power state (e.g., a sleep state). The period of time may be monitored by a processor included as a part of the printer or a processor external to the printer.

At optional Step <NUM>, the user may be instructed to agitate the cartridge. This may include prompting the user to change the cartridge on a user interface (Ul). In an example, the (UI) may be a graphical user interface (GUI) on the printer, or may be sent to a GUI of a mobile device or a similar GUI external to the printer (e.g., the monitor of a computer or other device to which the printer is operably connected). In an example, when the instruction message is sent to the Ul, the printer may enter a locked mode, which may disable or otherwise prevent the printer from accepting or printing any new print jobs, or beginning, starting, or the like, any scheduled print jobs, until the cartridge <NUM> is removed from the carriage <NUM> and agitated.

Step <NUM> may include pumping, moving, or the like, ink from at least one of the header tanks, such as header tanks <NUM>, <NUM>, or <NUM> along a path toward one or more ink cartridges such as <NUM> (e.g., through the tubing such as tube <NUM> connecting the ink cartridges to the header tanks). This may be done automatically after the time period of Step <NUM> has elapsed or other triggering event, such as a user manually starting the auto agitation routine by selecting an option on the UI discussed above, is detected. In an example, the elapsed period of time may be the amount of time since a portion of the ink contained in at least one of the header tanks was previously pumped from a header tank in a direction toward the ink cartridge(s) connected to that header tank. The ink may be pumped/moved from the header tanks toward the ink cartridges using one or more vacuum pumps, such as vacuum pump <NUM>. In an example, only a portion of the ink from the header tanks may move/pump all the way to the ink cartridges (e.g., not all of the ink will move into the ink cartridges). A portion of the ink may remain in the tubing between the header tanks and the ink cartridges. In an example, the entire amount of ink in the header tanks may be pumped from the tank so as to drain/completely empty the tank. Alternatively, a portion of ink may remain in the header tanks during the auto agitation process.

In an example, the triggering event may be the user manually activating the auto agitation routine. In another example, the triggering event may be the detection, by one or more sensors, of a potential issue (e.g., a potential clog, obstruction, or the like) in one of the print heads, one of the print nozzles, or in one of the tubes. In another example, the triggering event may be the replacement of one of the ink cartridges.

Step <NUM> may include circulating (e.g., pumping with a vacuum pump such as <NUM>) ink through the tubing such as tube <NUM>, in a direction from the ink cartridges back to the header tanks, such as header tanks <NUM>, <NUM>, or <NUM>. In an example, steps <NUM> and <NUM> may be performed to move ink from a single header tank toward a single ink cartridge (e.g., a cartridge containing white ink) connected to the header tank, and back into the header tank. In another example, ink may be moved from multiple header tanks toward multiple ink cartridges, and back to the header tanks as desired or needed. In an example, the header tanks may contain/include a level sensor configured to monitor the amount of ink in the header tanks, to prevent the header tank from overfilling with ink as it is pumped/circulated back from the direction of the ink cartridges.

Step <NUM> may include agitating the scan head <NUM>. This may include moving the scan head <NUM> along the x-direction gantry <NUM>, the y-direction gantry <NUM>, or a combination thereof to mix the ink in the header tanks <NUM>, <NUM>, or <NUM>. In an example, the scan head may move more rapidly, faster, or the like, during step <NUM> than when printing an image in order to cause the scan head to shake, vibrate, or the like, and mix the ink. In an example, the scan head may move at the same speed, or at a slower speed during the agitation of Step <NUM> than when printing an image, as needed. Step <NUM> may be performed before, after, during, or independently of Steps <NUM> or <NUM>. Likewise, in some examples, Step <NUM> may be performed independently of all other steps (e.g., on its own).

In an example, any one or more of Steps <NUM>-<NUM> may also be used as a startup/agitation process for the printer, such as when the printer is powered on or "awakened" from a sleep or low-power mode/state. Further, any one or more of Steps <NUM>-<NUM> may be performed multiple times (e.g., repeated more than once, run through two or more cycles, or the like) to mix the ink. For example, Steps <NUM> and <NUM> may be repeated any suitable number of times as desired or necessary. In an example, the system may automatically repeat one or more of Steps <NUM>-<NUM>, or, alternatively, a user may repeat any one or more of the steps as desired.

Step <NUM> may include applying a "tickle pulse" to one or more print heads, such as <NUM>, <NUM>, or <NUM>. In an example of <NUM>, the processor may cause a waveform (e.g., a current or voltage) to be applied to each of the one or more print heads that is not strong enough to eject a drop from any of the print nozzles on the print heads, but cause ink to move from the corresponding header tanks <NUM>, <NUM> or <NUM> to the corresponding print heads where the ink can move, slosh, or the like, within the print heads. Applying the tickle pulse may cause the ink to mix, be stirred, or the like, within/inside the print heads. Step <NUM> may be performed at the same time as any one or more of Steps <NUM>-<NUM> or may be performed separately as the user or system desires or deems necessary.

<FIG> illustrates another example of a method for improving ink jet nozzle health and printing reliability, and particularly a method for "reverse" purging the print heads, as introduced above. Step <NUM> may include moving a scan head, such as <NUM>, to a maintenance station, such as <NUM>, the maintenance station including a purge cap such as <NUM> and a wiper such as <NUM>, each described above. The purge cap may be placed, located, moved, or the like, below a print head. In an example, the print head may move to the location of the purge cap, such as by the print head being lowered to the maintenance station <NUM>, as described above. Additionally, or alternatively, the maintenance station <NUM> may move to the location of the print head in order to locate the purge cap below the print head. The purge cap may be caused to be located above one or more of the nozzles on the nozzle plate of the print head, such as nozzle plate <NUM>, or over an entire row of nozzles, such as <NUM> or <NUM>, to create at least a partial seal between the purge cap and at least one of: a nozzle, a row of nozzles, the nozzle plate, or the print head, at Step <NUM>.

Step <NUM> may include performing a reverse purge of at least one of: a print head, a nozzle plate located on the print head, the row of nozzles on the nozzle plate, or the particular nozzle in the row of nozzles, by operating the vacuum pump in a reverse direction. Step <NUM> may be accomplished by activating the vacuum pump such that the vacuum pump causes the purge cap to apply a positive pressure to the at least one of: the print head, the nozzle plate located on the print head, the row of nozzles on the nozzle plate, or the particular nozzle in the row of nozzles. This may aid in removing a clog or an obstruction in the print nozzle by pushing the clog/obstruction up through the nozzle. Further, Step <NUM> may additionally or alternatively be used, even when there is no clog in a nozzle, in order to mix, circulate, agitate, or the like, the ink in a particular nozzle with the ink in a particular header tank (e.g., push ink from a nozzle into the header tank) connected to the particular nozzle.

Step <NUM> may include operating the vacuum pump in a forward direction (e.g., reversing the direction of the vacuum pump compared to the direction of the operation of the vacuum pump in Step <NUM>) so as to apply a negative pressure at the purge cap to allow the ink or a clog/obstruction to be sucked/vacuumed out of the print head, a print nozzle, or from the nozzle plate. Step <NUM> may be optional and can be performed before, after, or independently of Step <NUM>, as needed or desired.

<FIG> illustrates another example of a method for improving ink jet nozzle health and printing reliability, and particularly a method for spitting while wiping, as introduced above. Step <NUM> may include ejecting an amount of ink from a print head such as <NUM>, <NUM>, or <NUM> onto the corresponding nozzle plate such as <NUM> of the print head. In Step <NUM>, the ink may not be ejected at a full/normal force, amount of pressure, speed, or the like, from the nozzles/print head as when printing an image, but may be at the force of, for example, a "tickle" pulse or at any other suitable force between the force used for a "tickle" pulse and that used for printing an image to a substrate.

Step <NUM> may include, simultaneously or substantially simultaneously with the ejecting of the ink onto the nozzle plate in Step <NUM>, wiping the nozzle plate with a wiper, such as <NUM>, which may move below the print head/nozzle plate. By ejecting the ink more slowly/with less pressure in Step <NUM> than when printing an image or an otherwise "normal" print job or print operation may allow the wiping of Step <NUM> to occur at substantially the same time as one another.

Step <NUM> may include cleaning the wiper. This may include rotating, turning, or the like, the wiper about an axle, such as <NUM> which may be a cylindrical rod connected, attached, or the like, to the wiper which allows the wiper to wipe against a piece of material, such as <NUM> (e.g., plastic, metal, or the like), which, in turn, may allow waste ink to be cleared from the wiper <NUM>. As the waste ink is removed from the wiper (e.g., immediately after or at substantially the same time as the wiper <NUM> wipes against the material <NUM>), it may fall or otherwise be caused to collect below the wiper and axle into a waste deposit such as <NUM>, which may be a well, depression, opening, compartment, or the like, located below the wiper <NUM> and axle <NUM>.

Step <NUM> may include removing the waste ink from the maintenance station, such as by sucking, vacuuming, or the like, from the maintenance station waste deposit using a vacuum pump such as <NUM>. Step <NUM> may be performed at the same time (e.g., immediately after, or a short amount of time, such as within a minute after) as Step <NUM>, or may be performed on a periodic basis or as necessary (as determined by the processor) or desired by the user. This "spitting while wiping" process may allow the nozzle plate to be cleared of ink without the ink being pushed back up into one of the print nozzles where it may mix with, and potentially contaminate "clean" ink being ejected from the print head when printing a new image or print job or print operation. It is understood that any one of Steps <NUM> to <NUM>, or a combination of Steps <NUM> to <NUM> may be repeated as necessary or desired by the user.

<FIG> illustrates another example of a method for improving ink jet nozzle health and printing reliability, and particularly a method for changing starting position of a print head. In a print job, when printing the same or substantially the same image multiple times in a row (e.g., over and over) to a plurality of similar substrates (each printing of the image to a substrate being a "print operation"), conventionally, the print heads will start in the same position for each print operation, move in the same pattern over the substrates, and end each print operation in the same position. Consequently, the same nozzles on the print head get used over and over again throughout the print job, while other nozzles are not used at all. Over time, this can degrade the print quality as the nozzles that are not used may become clogged or otherwise may not eject ink properly when it subsequently becomes time for their use, such as in a new or different print job.

To address this issue, in general, the initial starting position of a print head relative to a substrate for one or more print operations within a print job may be changed from or otherwise be different than the initial starting position of the print head relative to the substrate for other print operations within the print job. In this way, for one or more print operations, a different set of nozzles of the print head will be used to print the image on the substrate(s). As a result, the chance that only some nozzles will be used repeatedly for a given print job, or that some nozzles will go without use for extended periods of time, is reduced or even eliminated. The initial starting position of the print head for the one or more print operations where the initial starting position is altered or changed may be selected randomly, semi-randomly, or based on a predetermined algorithm.

More specifically, Step <NUM> may include printing, in a first print operation of a print job, a first image on a first substrate with the print head, such as print heads <NUM>, <NUM>, or <NUM>, starting the print operation in a first starting position. Accordingly, when printing an image on the substrate, such as <NUM>, the print head may employ one or more of the nozzles such as in the rows of nozzles <NUM>, <NUM> to print the first image, while other nozzles in the row of nozzles <NUM>, <NUM> may not be needed or otherwise used to print the first image.

Step <NUM> may include selecting a second starting position for the print head relative to the substrate(s). The second starting position may be selected randomly, semi-randomly, or based on a predetermined algorithm. The second starting position for the print head is different than the first starting position for the print head, relative to the substrates. In an example, the first starting position and/or the second starting position may be chosen, selected, or the like, by the processor of the printer, or a processor connected to the printer. In an example, the first starting position and/or the second starting position may be selected, chosen, or the like, by a user of the printer.

Step <NUM> may include printing, in a second print operation of a print job, a second image on a second substrate with the print head starting the print operation in the second starting position. As such, the print operation for printing the second image on the second substrate starts at a different portion of the surface of the substrate as compared to where the print operation for printing the first image on the first substrate was started. For example, the first starting position of the print head may be located such that the first image starts printing in the middle of the first substrate. In a subsequent print operation, the second starting position of the print head may be located such that the second image starts printing in a corner of the second substrate. Such variation of the starting position, e.g., in Step <NUM>, may allow one or more of the print nozzles used/utilized in Step <NUM> to be a different than one or more of the print nozzles used/utilized in Step <NUM>. Steps <NUM> and <NUM> may be repeated for any print operation of a print job, any subset of print operations of a print job, or for all or nearly all print operations in a print job. In some examples, the starting position of the print head for even the first print operation of a print job may be selected randomly, semi-randomly, or based on a predetermined algorithm. In some examples, which print operation or print operations within a print job for which Steps <NUM> and <NUM> are performed may also be selected randomly, semi-randomly, or based on a predetermined algorithm. In still other examples, a first starting position may be used for one or more (e.g., a first subset) print operations within a print job, and a second starting position may be used for one or more (e.g., a second subset) of other print operations within the print job. Of course, any number of starting positions may be selected and corresponding associated with one or more (e.g., third, fourth, etc., subsets) print operations within the print job as well. In an example, the starting position of the print head for each print operation of a print job (optionally excluding the first print operation) may be selected pursuant to Step <NUM>.

In an example, at least a portion or part of the first image may be the same as or identical to at least a portion or part of the second image. In a further example, the first image is the same as or identical to the second image, for example, when printing multiple identification cards, credit cards, or the like, which may have identical logos, markings, numbers, or the like on at least a portion of the card. By randomizing the starting location of the print head for print operations within a print job, and therefore, which print nozzles will print the image on the first card versus which nozzles will print the same image on a second card, it may prevent the nozzles on the print head from remaining idle (e.g., not ejecting ink) for an extended period of time. This may reduce or prevent the tendency of nozzles to have poor jetting of the ink and/or degrading, reducing, lowering, or the like, of the print quality.

It is understood that any of the methods described herein may be performed in conjunction with one another or independently. Further, some of the steps in any method may be repeated or omitted as necessary or desired.

<FIG> illustrates generally an example of a block diagram of a machine <NUM> upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform in accordance with some embodiments. For example, the machine <NUM> may be a printer in which the system described above is included, or a part or component of the printer, a component operably connected to the printer, or the like. The machine <NUM> may also be a personal computer (PC), a tablet PC, a control system, a mobile telephone, a web appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein.

Modules are tangible entities (e.g., hardware) capable of performing specified operations when operating. A module includes hardware. In an example, the hardware may be specifically configured to carry out a specific operation (e.g., hardwired). In an example, the hardware may include configurable execution units (e.g., transistors, circuits, etc.) and a computer readable medium containing instructions, where the instructions configure the execution units to carry out a specific operation when in operation. The configuring may occur under the direction of the execution's units or a loading mechanism. Accordingly, the execution units are communicatively coupled to the computer readable medium when the device is operating. In this example, the execution units may be a member of more than one module. For example, under operation, the execution units may be configured by a first set of instructions to implement a first module at one point in time and reconfigured by a second set of instructions to implement a second module.

The machine <NUM> may further include a display unit <NUM>, an alphanumeric input device <NUM> and a user interface (UI) navigation device <NUM>. In an example, the display unit <NUM>, alphanumeric input device <NUM> and UI navigation device <NUM> may be a touch screen display. The machine <NUM> may additionally include a storage device (e.g., drive unit) <NUM>, a signal generation device <NUM> (e.g., a speaker), a network interface device <NUM>, and one or more sensors <NUM>, such as a global positioning system (GPS) sensor, accelerometer, or another sensor. The machine <NUM> may include an output controller <NUM>, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, a card reader, etc.).

The storage device <NUM> may include a machine readable medium <NUM> that is non-transitory on which is stored one or more sets of data structures or instructions <NUM> (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein.

While the machine readable medium <NUM> is illustrated as a single medium, the term "machine readable medium" may include a single medium or multiple media (e.g., a centralized or distributed database, or associated caches and servers) configured to store the one or more instructions <NUM>.

The term "machine readable medium" may include any non-transitory medium that is capable of storing, encoding, or carrying instructions for execution by the machine <NUM> and that cause the machine <NUM> to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine-readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

The instructions <NUM> may further be transmitted or received over a communications network <NUM> using a transmission medium via the network interface device <NUM> utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) <NUM> family of standards known as Wi-Fi®, IEEE <NUM> family of standards known as WiMax®), IEEE <NUM>. <NUM> family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device <NUM> may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communications network <NUM>. In an example, the network interface device <NUM> may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term "transmission medium" shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine <NUM>, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

Claim 1:
A method for ink jet nozzle health and printing reliability of an ink jet printer, the method comprising:
printing a first image onto a first substrate (<NUM>) using a print head (<NUM>, <NUM>, <NUM>), wherein the print head (<NUM>, <NUM>, <NUM>) begins the printing of the first image from a first starting position, and wherein the print head includes a plurality of nozzles; characterised in that the method further comprises the steps of
selecting a second starting position different than the first starting position; and
printing a second image onto a second substrate using the print head (<NUM>, <NUM>, <NUM>), wherein the print head (<NUM>, <NUM>, <NUM>) begins the printing of the second image from the second starting position;
wherein at least a portion of the first image is the same as or identical to at least a portion of the second image.