Given the ubiquitous use of ink-jet printers, there are many types of ink-jet printing systems and many types of ink. Despite this variety, foaming of ink within the printing systems is common and can be caused differently from system to system. For example, in some systems, the foaming can be caused by surfactants, which are intended to adjust surface tension of the ink. In some instances, while the presence of negative pressure favorably prevents drooling from nozzles of a printhead, this negative pressure also can allow the ink to be mixed under suction with air, thereby producing more foam or bubbles.
Among other issues associated with foaming of ink, in some systems, the foam enters the supply line of the negative pressure source. This phenomenon can foul operation of the negative pressure system and/or harm the supply line because of the aggressive characteristics of the ink on certain materials.
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 embodiments in which the present general inventive concept may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present general inventive concept can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present general inventive concept. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present general inventive concept is defined by the appended claims.
Embodiments of the present general inventive concept are directed to systems and methods for preventing uptake of ink foam into a negative pressure pathway from an ink supply pathway of a printhead. In one embodiment, an ink supply system includes a reservoir and a foam regulator. The reservoir is configured to hold a volume of ink and configured to be in fluid communication with a fluid ejection structure. The foam regulator is operable in a first state in which the foam regulator permits application of negative pressure through the foam regulator to apply negative pressure to the fluid ejection structure and to the reservoir, and a second state in which the foam regulator blocks passage of ink foam from the reservoir through the foam regulator. In this way, the foam regulator prevents migration of ink foam into the negative pressure conduit and negative pressure source, thereby preventing cross-contamination of adjacent different colored ink supplies. Moreover, the foam regulator also prevents damage to the negative pressure conduit that might otherwise occur upon entry of the aggressive characteristics of the inks into the negative pressure conduit. Accordingly, the foam regulator contributes to increased longevity of the negative pressure conduit while maintaining color purity among the different color ink supplies.
These embodiments and additional embodiments are described in association with
Ink supply assembly 14 supplies ink to printhead assembly 12 and includes a reservoir 15 for storing ink. As such, ink flows from reservoir 15 to inkjet printhead assembly 12. In one embodiment, inkjet printhead assembly 12 and ink supply assembly 14 are housed together in an inkjet cartridge or pen. In some embodiments, ink supply assembly 14 is separate from inkjet printhead assembly 12 but still directly communicates ink to the printhead assembly 12 via a releasable connection with the ink supply assembly 14 being mounted directly above and at least partially supported by the printhead assembly 12. This embodiment is sometimes referred to as an on-axis configuration of the ink supply assembly 14. However, in other embodiments, the ink supply assembly 14 is positioned remotely from the printhead assembly 12, with the ink supply assembly 14 communicating ink to the printhead assembly 12 via an array of supply tubes. This embodiment is sometimes referred to as an off-axis configuration of the ink supply assembly 14.
Carriage assembly 16 positions inkjet printhead assembly 12 relative to media transport assembly 18 and media transport assembly 18 positions print media 19 relative to inkjet printhead assembly 12. Thus, a print zone 17 is defined adjacent to nozzles 13 in an area between inkjet printhead assembly 12 and print media 19. In one embodiment, inkjet printhead assembly 12 is a non-scanning type printhead assembly. As such, carriage assembly 16 fixes inkjet printhead assembly 12 at a prescribed position relative to media transport assembly 18. Thus, media transport assembly 18 advances or positions print media 19 relative to inkjet printhead assembly 12.
Electronic controller 20 communicates with inkjet printhead assembly 12, media transport assembly 18, and, in one embodiment, carriage assembly 16. Electronic controller 20 receives data 21 from a host system, such as a computer, and includes memory for temporarily storing data 21. Typically, data 21 is sent to inkjet printing system 10 along an electronic, infrared, optical or other information transfer path. Data 21 represents, for example, an image, a document, and/or file to be printed. As such, data 21 forms a print job for inkjet printing system 10 and includes one or more print job commands and/or command parameters.
In one embodiment, electronic controller 20 provides control of inkjet printhead assembly 12 including timing control for ejection of ink drops from nozzles 13. As such, electronic controller 20 operates on data 21 to define a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print media 19. Timing control and, therefore, the pattern of ejected ink drops, is determined by the print job commands and/or command parameters. In one embodiment, logic and drive circuitry forming a portion of electronic controller 20 is located on inkjet printhead assembly 12. In another embodiment, logic and drive circuitry is located remotely from inkjet printhead assembly 12.
As shown in
With further reference to
Because of this foam pathway that coincides with the negative pressure pathway, foam regulator 201 is interposed between reservoir 108 (and printhead 100) and negative pressure source 210. In one aspect, foam regulator 201 is positioned between negative pressure conduit 124 and negative pressure conduit 212. Moreover, to the extent that elements 124 and 212 form part of an overall negative pressure conduit, element 124 corresponds to a first portion of the negative pressure conduit, element 212 corresponds to a second portion of the negative pressure conduit, and foam regulator 201 is interposed between the respective first and second portions of the negative pressure conduit.
While float member 200 can take a variety of shapes, in one embodiment, float member 220 comprises a generally conical shape with a first end 224 that is substantially wider than a second end 226. In one embodiment, the first end 224 has a width (W2) that substantially matches (or is slightly less than) a width (W3) of lower portion 206 of chamber 205 and that is substantially less than a width (W1) of second end 226 of float member 220.
With this arrangement of float member 220 and chamber 205, the first end 224 of float member 220 covers substantially all of the foam 128 emanating from port 204 of conduit 124. As the amount of ink foam 128 increases and rises within lower portion 206 of chamber 205 over a period of time during operation of the printing system 200, the ink foam 128 buoyantly presses (as represented by directional arrow F) float member 220 upward through chamber 205 until second end 226 of float member 220 contacts and blocks port 213 of conduit 212, as illustrated in
As illustrated by
With this arrangement, float member 220 prevents foam 128 from entering conduit 212, and therefore blocks migration of foam 128 to negative pressure source 210. In addition to protecting negative pressure source 210 from ink foam via blocking conduit 212, this arrangement also temporarily reduces the amount of ink foam. In particular, even with the pathway of negative pressure closed, the ink continues to be pulled out of ink supply 140 (via conduit 114, reservoir 108, etc.) by capillary forces so that the free volume of ink 112 increases, and pressure within reservoir 108 drops. As result, some of the bubbles of ink foam 128 explode while some of the ink (of the ink foam 128) drains from conduit 124 (and chamber 205) back into reservoir 108 and/or ink supply 140.
Ultimately, upon a reduction in the volume of ink foam 128, float member 220 descends within chamber 205, restoring the application of negative pressure on ink 112 in reservoir 108 until an excessive amount of ink foam accumulates again in a volume that causes float member 220 to once again block conduit 212 to negative pressure source 210. It will be understood that the volume of chamber 205 is selectable to control the amount of ink foam permitted to build up before the float member 220 blocks conduit 212.
In some embodiments, float member 220 includes a rubber element 222 (or other resilient member) that creates a seal relative to port 213 of conduit 212 when float member 220 is pressed upward against port 213 by ink foam 128, as illustrated in
It will be understood that in some embodiments, in addition to incorporating foam regulator 201 as part of ink supply system 110, other measures (e.g. de-foaming agents) are taken to ameliorate a buildup of ink foam in ink supply system 110.
As shown in
In addition, by preventing entry of the ink foam, the respective foam regulators 201 protect the longevity of the conduit 212 (typically plastic tubing) for each ink supply system 302, 304, 306, 308 from the aggressive chemical characteristics of the ink.
As shown in
In some embodiments, method 400 further includes providing the foam regulator as a chamber that contains a float member that is freely movable within the chamber. A first portion of the chamber is arranged to be in fluid communication with the reservoir via a first portion of the negative pressure conduit (e.g. conduit portion 124) and a second portion of the chamber is arranged to be in fluid communication with a second portion (e.g. conduit portion 212) of the negative pressure conduit. Moreover, in some embodiments, method 400 additionally includes blocking access to the negative pressure conduit via the float member upon ink foam from the reservoir buoyantly pressing the float member upward against a top portion of the chamber and across an opening of the second portion of the negative pressure conduit.
Embodiments of the present general inventive concept neutralizes at least some of the effects of ink foam buildup in a printing system by preventing migration of the ink foam into a negative pressure pathway that is in communication with the ink being supplied to the printhead. In one embodiment, a buoyant element rises in response to the level of ink foam buildup such that the negative pressure pathway is generally maintained for the ink supply system until ink foam rises to a maximum level at which the position of the float member automatically prevented from migrating into the negative pressure source pathway.
Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.
Number | Name | Date | Kind |
---|---|---|---|
6234621 | Musser et al. | May 2001 | B1 |
6312119 | Kocher et al. | Nov 2001 | B1 |
6457820 | Cai et al. | Oct 2002 | B1 |
7188940 | Feliciano | Mar 2007 | B2 |
7344230 | Moynihan | Mar 2008 | B2 |
7543921 | Byun et al. | Jun 2009 | B2 |
20030122907 | Kim | Jul 2003 | A1 |
20040080590 | Jung et al. | Apr 2004 | A1 |
20050237367 | Hagen et al. | Oct 2005 | A1 |
20070052775 | Jung | Mar 2007 | A1 |
20070052779 | Cho | Mar 2007 | A1 |
20070292162 | Regev et al. | Dec 2007 | A1 |
20080036837 | Gray et al. | Feb 2008 | A1 |
Number | Date | Country | |
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20110102524 A1 | May 2011 | US |