Printing mechanisms, such as those used in desktop printers, may use one or more print cartridges, sometimes referred to as “pens,” which may shoot drops of liquid colorant, referred to generally herein as “ink,” onto a page. Each print cartridge may have a printhead formed with very small nozzles through which the ink drops are fired. To print an image, the printhead carriage carrying the printhead may be propelled back and forth across the page, firing drops of ink in a desired pattern as it moves. The particular ink ejection mechanism within the printhead may take on a variety of different forms known to those skilled in the art, such as those using piezo-electric or thermal printhead technology.
To clean and protect the printhead, a “service station” mechanism may be mounted within the printer chassis so the printhead can be moved over the station for maintenance. For storage, or during non-printing periods, the service stations may include a capping system which seals the printhead nozzles from contaminants and drying. To facilitate priming, some printers may have priming caps that are connected to a pumping unit to draw a vacuum on the printhead. During operation, partial occlusions or clogs in the printhead may be periodically cleared by firing a number of drops of ink through each of the nozzles in a clearing or purging process known as “spitting.” The waste ink may be collected at a spitting reservoir portion of the service station, known as a “spittoon.” After spitting, uncapping, or occasionally during printing, most service stations have a flexible wiper, or a more rigid spring-loaded wiper, that may wipe the printhead surface to remove ink residue, as well as any paper dust or other debris that has collected on the printhead. After wiping of the printhead by the wiper, the wiper may be scraped by a scraper to remove ink residue from the wiper.
The capping, spitting and wiping mechanisms of the service station may all be provided on a single service station sled for a variety of reasons, including reducing the space requirements of the service station. These multi-function service station sleds may not cap or uncap the printhead without also wiping the printhead and, in some cases, then scraping the wiper. Accordingly, a predetermined torque may be required in order to effect movement of the sled due to the multiple number of tasks that the sled may perform during each movement. Unnecessary wear and tear of the cap and/or the wiper may also occur because capping and/or wiping may not be required or desired during each movement of the sled. Moreover, the wiper, when it is scraped, may tend to flick ink from the wiper back onto the wiper or onto the printhead and the printhead carriage.
One embodiment of a printhead servicing mechanism comprises a printhead capping device that moves between a storage position and a printhead capping position, and a crank arm assembly that moves the printhead capping device between the storage and capping positions.
While it is apparent that the printer's components may vary, the typical printer 10 may include a chassis 12 surrounded by a housing 14 (in this figure chassis 12 is hidden from view by housing 14), typically manufactured of a plastic material. Sheets of print media may be fed through a printzone 16 to a printhead 18 which may be supported by a printhead carriage 20. Printhead 18 may comprise a plate on a lower surface of printhead carriage 20 that defines a printhead plane and that includes nozzles though which the ink is ejected to print an image. Printhead carriage 20 may be movably mounted on a carriage rod 22 for movement there along. The print media may be any type of suitable material, such as paper, card-stock, transparencies, mylar, and the like, but for convenience, the illustrated embodiment is described using a sheet of paper as the print medium. The printer may include a feed tray 24 for storing sheets of paper before printing. A series of motor-driven paper drive rollers 26 (one drive roller shaft including several drive rollers is shown in this view) may be used to move the print media from tray 24 into the printzone 16 for printing. After printing an image on a sheet of print media, the printhead may be moved into a servicing region 28 for servicing by a printhead servicing mechanism 30. The printhead servicing mechanism 30 will now be described.
Capping system 50 may include a cap 54, mounted on a cap gimbal 56, which in turn may be mounted on a cap carrier 58. Gimbal 56 may allow a slight rocking motion of cap 54 with respect to cap carrier 58 such that upon contact of cap 54 with printhead 18 (see FIG. 1), the cap may align itself with the printhead so that the upper rim of cap 54 may squarely abut against the printhead surface. In this manner a seal of printhead 18 may be accomplished. Positioned below cap carrier 58 may be a crank arm assembly 60 including a linkage arm 62 which may be secured at a first end 64 to cap carrier 58 and at a second end 66 between the two arms 68a and 68b of a crank 68. Crank arm 68a may be secured at its opposite end 70a to a first gear 72 of a compound gear assembly 74. First gear 72 may be engaged with a second, larger gear 76 that may be selectively engaged by a rack 78 on sled 32. Rack 78, for ease of illustration is shown on a lower edge surface of sled 32. However, in another embodiment rack 78 may be positioned inwardly from an edge surface of sled 32 such that rack 78 is not aligned with rack 42, which may also be positioned on a lower surface of sled 32. “Compound” gear assembly may be interpreted as meaning a gear assembly wherein rotation of one gear through a first angle may result in rotation of a second gear through a second angle that is different than the first angle. In the embodiment shown, compound gear assembly 74 comprises first and second gears 72 and 76, respectively, wherein the first and second gears are of different size so as to achieve differing angles of rotation when the two gears rotationally mate with one another. In other embodiments, gears 72 and 76 may be of the same size or may be of a different size than the size shown in the illustrated embodiment. Second end 66 of linkage arm 62 and the two arms 68a and 68b of crank 68 may be pivotally secured together with a fastener 80, also referred to as a pin, shown in dash lines.
Capping system 50 may further include a support structure 82 that may comprise first and second side walls 84 and 86 (see FIG. 3), respectively, wherein each wall may include at least one groove 88 and 90 (see FIG. 3), respectively, therein. Cap carrier 58 may include a first pair of legs 92 each having a projection 94 adapted to be received within groove 88 of side wall 84. Similarly, cap carrier 58 may include a second pair of legs 96 each having a projection 98 adapted to be received within groove 90 of side wall 86 (see FIG. 3). In this manner, movement of crank arm assembly 60 may operate to move cap carrier 58 in an upward direction 100 or in a downward direction 102 parallel to “y” direction 52 and along a capping axis 104, without attendant movement in the “x” or “z” directions 106 and 108, respectively. In other embodiments, cap carrier 58 may include only one leg for contacting either of side walls 84 or 86. In still other embodiments, any alignment device may be utilized to ensure “y” direction 52 movement of cap carrier 58 in response to movement of linkage 62. For example, in an alternate embodiment, legs 92 and 96 may each include a groove therein, wherein side walls 84 and 86 each may include a projection that is received within the grooves of legs 92 and 96, respectively. In another alternate embodiment, projections 94 and 98 may be received within a track on side walls 84 and 86, instead of within a groove as shown in the illustrated embodiment. In yet another alternate embodiment, projections 94 and 98 may be biased against an elongate stop surface by a biasing element such that the projections move along, and in contact with the elongate stop surface. In the embodiment shown, grooves 88 and 90 are each positioned extending vertically. However, in another embodiment, grooves 88 and 90 may be inclined with respect to a vertical axis such that cap carrier 58 may have an inclined upward movement as it is moved from the storage to the capping position.
Support structure 82 may further comprise a crank arm support structure 110 wherein a first wall 110a of the structure may support a connecting rod 112 that may connect first gear 72 and arm 68a of crank 68 and a second wall 110b of the structure that may support a protrusion 114 (shown in dash lines) extending outwardly from crank arm 68b. Protrusion 114 and connecting rod 112 may be aligned with a rotational axis of gear 72, and first and second crank arms 68a and 68b may be fixedly secured together by fastener 80, such that rotation of gear 72 may result in simultaneous rotation of crank arms 68a and 68b.
In
In
In general, gear 76 may be sized such that movement of gear 76 through about an angle 118 in a range of one to forty degrees may move gear 72 through about an angle 122 in a range of one hundred and seventy to one hundred and ninety degrees, which in turn may move crank arms 68a and 68b through about an angle 124 in a range of one hundred and seventy to one hundred and ninety degrees. In one example, gear 76 may be sized to move through about an angle of three degrees which may cause gear 72 to move through about an angle of one hundred and eighty degrees. In another example, gear 76 may be sized such that it may move through about an angle of twenty five degrees which may move gear 72 through about an angle of one hundred and eighty degrees.
In the embodiment shown, movement of cap 54 upwardly in “y” direction 52 takes place without any appreciable movement in the “x” or “z” directions 106 and 108. Moreover, cap 54 may be moved upwardly about a distance 129, as fastener 80 is moved through vertical distance 128, wherein the crank arms 68a and 68b may each have a length approximately half of distance 129 and wherein linkage arm 62 may have a length approximately the same as distance 129. Accordingly, capping mechanism 50 may result in “y” movement (i.e., movement in the y direction 52 without any appreciable movement in the x or z directions) of cap 54 through about a distance 129, wherein the “y” dimension storage space required for crank arm assembly 60 is only approximately half of the “y-throw” distance 129 of cap 54. Additionally, due to the “y” direction movement of cap 54, the “x” and “z” dimension storage space requirements of cap 54 may be no larger than cap carrier 58. In other words, the footprint of cap carrier 58 may be the only space required for storing of capping system 50 because the cap carrier does may not travel through a ramped movement in the “x” or “z” directions to reach its upward capping position. The relatively small space requirements for capping system 50, namely a “y” storage space requirement that is only half that of the “y throw” distance 129, and an “x” and “z” storage space requirement that is only as large as the footprint of cap carrier 58, may allow a printing mechanism 10 in which capping system 50 is installed to be manufactured in a relatively small size. Moreover, as will be discussed below, capping system 50 may be operated at selective times so that both capping and wiping need not be conducted during every service of printhead 18 (see FIG. 1).
Return movement of sled 32 in direction 140 may act to lower cap 54 once rack 78 is moved from zone 134 back into zone 132. Continued movement of rack 78 in direction 140 and through zone 132 may result in full lowering of cap 54 into the lowered position shown in FIG. 6. Continued movement of rack 78 into and throughout zone 130 may not act to raise cap 54 from its lowered position.
The illustrated embodiment of servicing mechanism 30 of the present invention may allow cap 54 to be moved into engagement with printhead 18 without requiring simultaneous movement of wipers 36 across scrapers 136. This may eliminate unnecessary scrape events with the printhead carriage 20 (see
Other enhancements may be made to the capping system wherein such variations and modifications of the concepts described herein fall within the scope of the claims below.
Number | Name | Date | Kind |
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5257044 | Carlotta et al. | Oct 1993 | A |
5867187 | Toniolo | Feb 1999 | A |
6309044 | Gaarder | Oct 2001 | B1 |
Number | Date | Country | |
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20040212656 A1 | Oct 2004 | US |