Patent Application
20170274659
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.
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.
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.
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
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
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.
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.
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.
