Patent Publication Number: US-9849676-B2

Title: Printer including a spit zone

Description:
BACKGROUND 
     An inkjet printing system, as one example of a fluid ejection system, may include a printhead, an ink supply which supplies liquid ink to the printhead, and an electronic controller which controls the printhead. The printhead, as one example of a fluid ejection device, ejects drops of ink through a plurality of nozzles or orifices and toward a print medium, such as a sheet of paper, so as to print onto the print medium. In some examples, the orifices are arranged in at least one column or array such that properly sequenced ejection of ink from the orifices causes characters or other images to be printed upon the print medium as the printhead and the print medium are moved relative to each other. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating one example of an inkjet printing system. 
         FIG. 1A  is a block diagram illustrating another example of an inkjet printing system. 
         FIG. 2A  is a block diagram illustrating one example of an inkjet printing system during a spit. 
         FIG. 2B  is a block diagram illustrating another example of the inkjet printing system of  FIG. 2A  during a spit. 
         FIG. 3  is a chart illustrating one example of the movement of a printhead assembly for a spit. 
         FIG. 4  is a flow diagram illustrating one example of a method for maintaining nozzles of a printhead assembly. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise. 
     To maintain the heath of the nozzles of a printhead assembly, inkjet printers may eject ink from the nozzles during spits (i.e., outside of printing to a print medium). The ink ejected during spits (i.e., maintenance ink) is stored within the printer. When pigment ink is ejected from nozzles of a printhead assembly at a fixed location during a spit, the volatile components of the ink evaporate, leaving behind a semi-solid substance. Successive spits may cause a stalagmite like growth that may rapidly climb to a height that may cause problems within a printer. The growth may run into the carriage assembly, printhead assembly, or other moving parts of the printer, which may result in maintenance ink ending up on a printed page or cause a malfunction within the printer. In a small printer there is limited space available to store maintenance ink. In any printer, costs are incurred to design and include additional parts and features to move the accumulated maintenance ink out of the path of the printhead assembly and/or other printer components. In addition, mechanical designs to move the maintenance ink may behave in an unpredictable fashion and are sensitive to environmental factors and testing protocols. 
     Accordingly, instead of ejecting ink at a fixed location during spits, the example printers described herein include moving the printhead assembly during spits to evenly distribute the maintenance ink throughout a spit zone. No mechanical components are needed to move the maintenance ink out of the path of the printhead assembly and/or other printer components. Thus, compared to printers including mechanical components to move the maintenance ink, printers as described herein including spit zones where maintenance ink is distributed for storage use fewer parts and are more reliable, less expensive, and more conducive to a user or service-replaceable module. 
       FIG. 1  is a block diagram illustrating one example of an inkjet printing system  10 . Inkjet printing system  10  includes a controller  12 , a printhead assembly  14 , and a spit zone  22 . Printhead assembly  14  includes nozzles  16  to eject ink drops as indicated at  18 . Spit zone  22  is to store maintenance ink. Controller  12  is to move printhead assembly  14  over spit zone  22  as indicted at  20  while ink is ejected from nozzles  16  during spits. 
       FIG. 1A  is a block diagram illustrating another example of an inkjet printing system  100 . Inkjet printing system  100  includes a fluid ejection assembly, such as printhead assembly  102 , and a fluid supply assembly, such as ink supply assembly  110 . In the illustrated example, inkjet printing system  100  also includes a service station assembly  104 , a carriage assembly  116 , a print media transport assembly  118 , and an electronic controller  120 . While the following description provides examples of systems and assemblies for fluid handling with regard to ink, the disclosed systems and assemblies are also applicable to the handling of fluids other than ink. 
     Printhead assembly  102  includes at least one printhead or fluid ejection device which ejects drops of ink or fluid through a plurality of orifices or nozzles  108 . In one example, the drops are directed toward a medium, such as print media  124 , so as to print onto print media  124 . Print media  124  includes any type of suitable sheet material, such as paper, card stock, transparencies, Mylar, fabric, and the like. In one example, nozzles  108  are arranged in at least one column or array such that properly sequenced ejection of ink from nozzles  108  causes characters, symbols, and/or other graphics or images to be printed upon print media  124  as printhead assembly  102  and print media  124  are moved relative to each other. 
     Ink supply assembly  110  supplies ink to printhead assembly  102  and includes a reservoir  112  for storing ink. As such, in one example, ink flows from reservoir  112  to printhead assembly  102 . In one example, printhead assembly  102  and ink supply assembly  110  are housed together in an inkjet or fluid-jet print cartridge or pen. In another example, ink supply assembly  110  is separate from printhead assembly  102  and supplies ink to printhead assembly  102  through an interface connection  113 , such as a supply tube and/or valve. 
     Carriage assembly  116  positions printhead assembly  102  relative to print media transport assembly  118  and print media transport assembly  118  positions print media  124  relative to printhead assembly  102 . Thus, a print zone  126  is defined adjacent to nozzles  108  in an area between printhead assembly  102  and print media  124 . In one example, printhead assembly  102  is a scanning type printhead assembly such that carriage assembly  116  moves printhead assembly  102  relative to print media transport assembly  118 . 
     Service station assembly  104  provides for spitting, wiping, capping, and/or priming of printhead assembly  102  to maintain the functionality of printhead assembly  102  and, more specifically, nozzles  108 . For example, service station assembly  104  may include a rubber blade or wiper which is periodically passed over printhead assembly  102  to wipe and clean nozzles  108  of excess ink. In addition, service station assembly  104  may include a cap that covers printhead assembly  102  to protect nozzles  108  from drying out during periods of non-use. In addition, service station assembly  104  includes a spit zone  106  into which printhead assembly  102  ejects ink during spits to insure that reservoir  112  maintains an appropriate level of pressure and fluidity, and to insure that nozzles  108  do not clog or weep. Functions of service station assembly  104  may include relative motion between service station assembly  104  and printhead assembly  102 . 
     Electronic controller  120  communicates with printhead assembly  102  through a communication path  103 , service station assembly  104  through a communication path  105 , carriage assembly  116  through a communication path  117 , and print media transport assembly  118  through a communication path  119 . In one example, when printhead assembly  102  is mounted in carriage assembly  116 , electronic controller  120  and printhead assembly  102  may communicate via carriage assembly  116  through a communication path  101 . Electronic controller  120  may also communicate with ink supply assembly  110  such that, in one implementation, a new (or used) ink supply may be detected. 
     Electronic controller  120  receives data  128  from a host system, such as a computer, and may include memory for temporarily storing data  128 . Data  128  may be sent to inkjet printing system  100  along an electronic, infrared, optical or other information transfer path. Data  128  represent, for example, a document and/or file to be printed. As such, data  128  form a print job for inkjet printing system  100  and includes at least one print job command and/or command parameter. 
     In one example, electronic controller  120  provides control of printhead assembly  102  including timing control for ejection of ink drops from nozzles  108 . As such, electronic controller  120  defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print media  124 . Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. In one example, logic and drive circuitry forming a portion of electronic controller  120  is located on printhead assembly  102 . In another example, logic and drive circuitry forming a portion of electronic controller  120  is located off printhead assembly  102 . 
     Electronic controller  120  also controls printhead assembly  102  during spits for maintaining nozzles  108 . Instead of ejecting ink drops from nozzles  108  at a fixed location within spit zone  106  during spits, electronic controller  120  moves printhead assembly  102  relative to spit zone  106  such that the ejected ink drops (i.e., maintenance ink) is distributed throughout spit zone  106 . In one example, spit zone  106  has a volume large enough to store all the maintenance ink accumulated during the expected lifetime of printing system  100 . In other examples, printing system  100  includes a user or service-replaceable spit zone module that may be periodically replaced when full of maintenance ink. 
       FIG. 2A  is a block diagram illustrating one example of an inkjet printing system  200  during a spit. Printing system  200  includes a controller  202 , a printhead assembly  204 , and a service station assembly  210  including a spit zone  212 . Printhead assembly  204  includes nozzles  206  to eject ink as indicated at  208 . In one example, ink  208  is a pigment ink or another ink that leaves behind a semi-solid or solid substance once the volatile components of the ink evaporate. Controller  202  is communicatively coupled to printhead assembly  204  through a communication path  203  to control the movement of printhead assembly  204  and the ejection of ink drops from nozzles  206 . 
     Spit zone  212  is located under the scanning path of printhead assembly  204 . Spit zone  212  may include a recessed region or another suitable region under the scanning path of printhead assembly  204  capable of storing a predefined volume of maintenance ink. In one example, spit zone  212  is arranged outside a print zone of printhead assembly  204 , such as between a print zone and a mechanical stop of printing system  200 . In another example, spit zone  212  is arranged inside a print zone of printhead assembly  204  and controller  202  prevents spitting when a print medium is present within the print zone. While one spit zone  212  is illustrated in  FIG. 2A , in other examples printing system  200  may include two spit zones or another suitable number of spit zones along the scanning path of printhead assembly  204 . 
     Controller  202  controls the movement of printhead assembly  204  during a spit such that ink ejected from nozzles  206  of printhead assembly  204  is distributed within spit zone  212 . Printhead assembly  204  may be moved at a constant speed over spit zone  212  during a spit. In one example, controller  202  sets a starting position for a spit within spit zone  212  based on the ending position for a previous spit within spit zone  212  to distribute the maintenance ink evenly over spit zone  212 . Maintenance ink  214  may be stored in spit zone  212  in tile-like segments  216 , where each tile-like segment  216  is formed during a single spit. Thus, in the example illustrated in  FIG. 2A , spit zone  212  is storing maintenance ink  214  for four spits  216  of various lengths. In this example, printhead assembly  204  is moving over spit zone  212  to the right as indicated by arrow  220 . Therefore, a subsequent spit may start next to a previous spit within spit zone  212  until the maintenance ink from subsequent spits reaches the right border of spit zone  212 . Once spit zone  212  is mostly or completely covered by a first layer of maintenance ink  214 , a second layer of maintenance ink may be stacked on the first layer during subsequent spits. 
     The length of each spit  216  is based upon the speed of printhead assembly  204  relative to spit zone  212  and the number of drops for the spit. For example, a flying spit (i.e., a spit during printing) including 20, 75, or 100 drops of ink with printhead assembly  204  moving at 2 inches per second (ips) relative to spit zone  212  may result in a spit length of 0.63, 1.25, or 1.53 mm, respectively. In another example, a spit after coming out of a printhead assembly cap including 150 or 500 drops of ink with printhead assembly  204  moving at 2 ips may result in a spit length of 2.10 or 6.05 mm, respectively. In another example, a spit prior to going into a printhead assembly cap including 200 or 500 drops of ink with printhead assembly  204  moving at 2 ips may result in a spit length of 2.66 or 6.05 mm, respectively. In another example, a pen recovery spit including 1000 drops of ink with printhead assembly  204  moving at 2 ips may result in a spit length of 11.69 mm. In other examples, spits may include a different number of drops of ink and/or printhead assembly  204  may move at another suitable speed relative to spit zone  212  to provide spits having different lengths. 
       FIG. 2B  is a block diagram illustrating another example of inkjet printing system  200  of  FIG. 2A  during a spit. In this example, controller  202  is moving printhead assembly  204  to the left relative to spit zone  212  during a spit as indicated by arrow  222 . Also illustrated in  FIG. 2B  are multiple layers of maintenance ink  214  due to a plurality of spits  216  of various lengths distributed throughout spit zone  212 . 
       FIG. 3  is a chart  300  illustrating one example of the movement of a printhead assembly for a spit, such as printhead assembly  102  previously described and illustrated with reference to  FIG. 1A  or printhead assembly  204  previously described and illustrated with reference to  FIG. 2A . A carriage assembly axis, such as for carriage assembly  116  previously described and illustrated with reference to  FIG. 1A , along which the printhead assembly may move, is indicated at  302 . In this example, the direction of movement of the printhead assembly during the spit is to the right along carriage assembly axis  302  as indicated by arrow  304 . In other examples, the direction of movement of the printhead assembly during the spit may be in the opposite direction along carriage assembly axis  302 . The speed of the printhead assembly along carriage assembly axis  302  is indicated by  306 . 
     Prior to a spit, the printhead assembly may be moving toward a spit zone at a first speed as indicated at  308 , such as between 10 and 50 ips (e.g., 40 ips). At  310 , as the printhead assembly nears or reaches the spit zone, the speed of the printhead assembly is modified to prepare for the spit. In one example, the location where the speed is modified is calculated based on the start position for the spit within the spit zone. The start position for the spit may be based upon the ending position of a prior spit. The speed of the printhead assembly is slowed to a second speed less than the first speed as indicated at  312 , such as between 1 and 5 ips (e.g., 2 ips). At  314 , the spit is evoked. After a predetermined delay indicated at  320  for the printhead assembly to start ejecting ink from the nozzles after the spit is evoked, the spit begins at  316 . The spit continues for the length of the spit as indicated at  322  based on the number of ink drops for the spit and the speed of the printhead assembly relative to the spit zone. After the spit is completed at  318 , the printhead assembly may be brought to a controlled stop. 
       FIG. 4  is a flow diagram illustrating one example of a method  400  for maintaining nozzles of a printhead assembly. At  402 , method  400  includes moving a printhead assembly through a spit zone, the printhead assembly comprising nozzles to eject ink drops. At  404 , method  400  includes ejecting ink from the nozzles during a spit while the printhead assembly is moved through the spit zone. In one example, method  400  further includes setting a starting position within the spit zone for a subsequent spit based on an ending position within the spit zone of a previous spit such that ink from multiple spits is distributed throughout the spit zone. In another example, method  400  further includes moving the printhead assembly at a first speed prior to reaching the spit zone and moving the printhead assembly through the spit zone at a second speed less than the first speed. 
     Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.