Inkjet printheads require regular servicing in order to maintain the printheads and the quality of print jobs. Although there are many types of servicing systems and service stations, three pen service procedures involve wiping, spitting and capping. Wiping is a process by which the printhead nozzles are engaged with a scraper, typically rubber, to clean accumulated ink and debris off the nozzles. Spitting is a step that involves positioning the printheads over a waste ink receptacle—a spittoon—and causing the inkjet printhead to eject a volume of ink through the nozzles into the spittoon. Spittoons are simply receptacles that collect the waste ink. Sometimes spittoons are lined with absorbent material to retain the waste ink. Capping involves positioning the printheads in physical contact with a closely fitting cap—typically rubber or some other elastomer—to maintain a controlled atmosphere environment around the printheads during periods of inactivity.
Many inkjet printer service stations are configured for performing each of these three servicing tasks, and there are many variations in the order and frequency of the three servicing tasks. However, printhead servicing does not address issues relating to ink supply for the pen.
Many hardcopy devices that rely upon inkjet printing technology include service stations for maintaining the quality of the printheads, and thus the quality of the print jobs. A schematic representation of an inkjet printer according to an illustrated embodiment of the present invention is shown in the drawings. It will be appreciated that like reference numerals are used throughout the specification to identify like structural features found in more than one drawing figure.
With reference to
A carriage 16 mounted on a shaft 18 that has its opposite ends mounted to a printer chassis 19 to support in an operative position relative to paper 12 a set of four inkjet writing instruments, known as print cartridges, and labeled 20, 22, 24, and 26, respectively. Fewer print cartridges or more print cartridges may be used in different printers. As detailed below, each of the inkjet print cartridges 20 through 26 has at least one printhead 28 on the lower side of the print cartridges facing the printzone 14. Each printhead 28 is adapted for expelling minute droplets of ink or other fluids to form dots on adjacently positioned paper 12 in the print zone 14. Each printhead 28 generally consists of a drop generator mechanism and a number of columns of ink drop firing nozzles. Each column of nozzles, or a selected subset of nozzles, selectively fires ink droplets, each droplet typically being only a tiny liquid volume, that are used to create a predetermined print matrix of dots on the adjacently positioned paper as the printhead is scanned across the media. A given nozzle of the printhead is used to address a given matrix column print position on the paper. Horizontal positions, matrix pixel rows, on the paper are addressed by repeatedly firing a given nozzle at matrix row print positions as the pen is scanned across the paper. Thus, a single sweep scan of the printhead across the paper can print a swath of dots. The paper is advanced incrementally relative to the inkjet printheads to permit a series of contiguous swaths.
Inkjet printer 10 is shown as a full color inkjet system and therefore includes inks for the subtractive primary colors, cyan, yellow, magenta (CYM) and a true black (K). By way of example, print cartridge 20 contains cyan ink, print cartridge 22 yellow ink, print cartridge 24 magenta ink, and print cartridge 26 black ink. Different or additional colorants, such as, for example, lighter or darker shades of magenta and/or cyan, may of course be used. While the illustrated color print cartridges 20, 22, and 24 each use a dye-based ink, other types of inks may also be used, such as paraffin-based inks, as well as hybrid or composite inks having both dye and pigment characteristics.
Carriage 16 and thus print cartridges 20, 22, 24 and 26 are mounted on shaft 18 for shuttle-type reciprocating movement over media 12. Shaft 18 and carriage 16 are mounted on printer chassis 19. A carriage motor 21, typically a servo motor that is connected via circuitry 25 to controller 90 and to carriage 16 with a drive belt 27 (illustrated schematically), moves or “scans” carriage 16 during printing in a back and forth direction transverse to the direction of media advancement through the printzone 14. It is common in the art to refer to the scanning direction as the x-axis, the paper feed direction through the printzone as the y-axis, and the ink drop firing direction as the z-axis. That convention is used herein.
As noted, carriage 16 is under the control of the printer controller 90. The position of carriage 16 relative to paper 12 in the direction along the x-axis is determined by way of an encoder strip 23 that has its opposite ends mounted to the printer chassis 19. The encoder strip 23 extends past and in close proximity to an encoder or optical sensor (not shown) carried on carriage 16 to thereby signal to the printer controller 90 the position of the carriage assembly 16 relative to the encoder strip 23.
The paper 12 is incrementally advanced through the printzone 14 by a paper transport mechanism (not shown), typically in-between scans of the carriage 16. An encoder, typically a disk encoder, and associated servo systems are one of the methods often employed for controlling the precise incremental advance of the media. This incremental advance is commonly called “linefeed.” Precise control of the amount of the advance, the linefeed distance, contributes to high print quality. The paper advance mechanisms must move the paper 12 through the printzone 14 the desired distance with each incremental advance, at the desired rate, and so that the paper is oriented correctly relative to the printheads 28.
Each illustrated print cartridge 20, 22, 24 and 26 is individually coupled to a respective ink supply main reservoir 30, 32, 34 and 36, by separate flexible ink delivery tube or other conduit 40, 42, 44 and 46, respectively, in what is known as an “off axis” ink delivery system. An off axis system may be contrasted with a replaceable, self-contained ink delivery system where each print cartridge has a reservoir that carries the entire ink supply as it reciprocates along the x-axis, and is thus called an “on axis” delivery system. Each pen 20 through 26 includes an on-board reservoir or chamber for holding a volume of ink that is typically smaller than the volume of ink contained in the main reservoirs 30 through 36. The main reservoirs 30 through 36 are typically replaceable ink-in-foam or spring-in-bag designs, but other reservoir designs may also be used.
A service station shown generally and schematically in dashed lines at 50 services the printheads 28 associated with each of the pens 20, 22, 24 and 26. Service station 50 includes a pen wiper station 52 and printhead seal members 60, 62, 64 and 66. As detailed below, printhead seal members 60 through 66 are components of the ink supply main reservoirs 30 through 36. Wiper station 52 is positioned relative to pens 20 through 26 such that when the printer controller 90 causes carriage 16 to move along the x-axis in the direction of arrow A in
The ink supply main reservoirs 30, 32, 34 and 36 may be used as components of the service station 50. That is, the main supply reservoirs 30 through 36 may be used to receive ink directly from the printheads 28 of the print cartridges 20 through 24, recycle ink spit during servicing, and cap the printheads 28 during storage, in addition to supplying ink to the printheads 28. It will be appreciated that because the main ink supply reservoirs 30 through 36 are located in the illustrated embodiment below the pens 20 through 26, it may be necessary in some circumstances to include an optional pump and appropriate valves and/or sensors, illustrated generally with reference number 41, to assist with delivery of ink through conduits 40 through 46 from ink supply main reservoirs 30 through 36 to the associated pens 20 through 26. Conduits 40 through 46 are typically flexible tubing.
As may be seen in
With reference now to
A single print cartridge, ink supply reservoir and printhead seal are illustrated in
Referring specifically to
When the printer controller 90 determines that a printhead 28 needs to spit to maintain the health of nozzles 72, or for some other reason servicing is required, the controller 90 causes carriage 16 to be positioned relative to the ink supply reservoirs 30 through 36 such that the printheads 28 are aligned over the corresponding printhead seal members 60, 62, 64 and 66. When the print cartridges 20 through 26 and their associated printheads 28 and the associated printhead seal members 60 through 66 are aligned, controller 90 causes carriage motion to stop, and the controller 90 and actuator 33 cooperate to move reservoirs 30 through 36 upwardly as indicated with arrow B in
Ink 71 spit from printhead 28 is illustrated schematically in
By recycling the ink in the manner just described, overall consumer ink costs are reduced and the printer need not be taken out of service to eliminate waste ink in a spittoon. Moreover, the mess associated with waste ink in spittoons, and possible environmental consequences of throwing out waste ink, are eliminated. And by eliminating the hardware associated with spittoons and the associated mechanisms, valuable space in the printer housing are freed up for other components, or for reduction in the size and cost of the printer. Finally, since the print cartridges 20 through 26 are brought into a sealing engagement with the printhead seal members 60 through 66 when spitting occurs, any ink aerosolized during spitting is recycled, eliminating the risk that ink thus expelled from one printhead 28 may cross contaminate adjacent printheads 28.
After spitting as described above, the print cartridges 20 may return to printing, undergo other servicing, or be capped for storage. It will be appreciated that in the case where the print cartridges 20 through 26 are to be stored after spitting, then the sealing engagement described above between print cartridges 20 through 26 and printhead seal members 60 through 66 is maintained. When the print cartridges 20 through 26 and their associated printheads 28 are to be stored between periods of printing, the carriage 16 and print cartridges 20 through 26 are positioned over the ink supply reservoirs 30 through 36 as shown in
In the embodiment illustrated in
It will be appreciated that single-piece printhead seal member 100 may be used in a printer that utilizes more or less pens than the four illustrated herein.
The ink supply reservoirs 30 through 36 are replaceable. The printhead seal members may be fabricated such that they are replaced when the ink supply reservoirs are replaced, or the seal members may be reused on the replacement reservoirs if desired. The printhead seal members may thus be made as replaceable consumable components, as reusable components, or as permanent components or any combination.
Although preferred and alternative embodiments of the present invention have been described, it will be appreciated by one of ordinary skill in this art that the spirit and scope of the invention is not limited to those embodiments, but extend to the various modifications and equivalents as defined in the appended claims.
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Number | Date | Country | |
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20040075702 A1 | Apr 2004 | US |