Patent Publication Number: US-6659587-B2

Title: Waste fluid collection container

Description:
BACKGROUND AND SUMMARY 
     The present invention relates generally to fluid ejection devices and, more particularly, to a waste fluid collection container for collecting waste fluid ejected from such a device. 
     There are numerous situations where one needs to collect waste fluids. For example, if waste fluids are released inside machinery, such as a copier or printer, it can be necessary to collect these fluids so that they do not damage the surrounding machinery. Also, when changing the oil in an automobile, the oil must be collected and brought to a safe disposal location. To save the time and cost associated with emptying or changing collection containers, it is desirable to maximize the collection potential of a collection container. 
     Ink jet printers are a specific example of machinery that produces waste fluid, e.g., ink. In addition to ejecting ink onto paper or other substrates, ink jet printers also eject ink at other times. As part of the printhead maintenance routine, many ink jet printers eject ink periodically to keep them unclogged and working. This is referred to in the art as spitting. A printer controller will position the print cartridge at a maintenance station having a spit station or spittoon and cause the printhead to eject ink into the spittoon after a print cartridge has been away from a maintenance station for a specific length of time. The printer controller does this to prevent the ink or meniscus in the little used nozzles from drying and becoming too viscous. A receptacle is used to collect this ink in order to prevent a mess from being created and to prevent damage to other components of the printer. 
     Some printheads also eject ink during a priming process. For example, some priming processes involve applying a vacuum to the front face of the printhead to pull ink through the nozzles to initially prime the printhead or remove air bubbles or dried ink. A receptacle may also be used to collect ink ejected during such a priming process. When the printhead nozzle face ejects ink, ink that is removed from the nozzles (waste ink) is either ejected directly into a receptacle having a waste pad therein, or it is transported indirectly through ducts or tubing to the receptacle and waste pad via a vacuum pump and tubing. 
     More specifically, ink is absorbed into the pad. However, sometimes the waste pad will stop absorbing and overflow with ink. This happens because the ink does not flow through the whole pad, but flows a ways into it and stops progressing. This happens most often with inks containing carbon. The ink remains suspended some distance from the floor of the waste receptacle. The water evaporates out of the ink inside the perimeter of the hole thus impeding the ability for fresh ink to spread through the foam. 
     Previous receptacle designs were simply flat on the bottom. When the tar-like ink residue impedes new ink from spreading throughout the foam, the new ink fills the hole in the waste pad and rises out of the receptacle itself. This is a major concern since ink leaking out of the printer will upset the customer. 
     Embodiments of the present invention include a waste fluid collection container having a floor defined by a periphery. The floor has a set of raised ridges located extending outward from a central area. The container also includes a wall or walls located along said periphery and attached to and surrounding the floor. The container further includes a fluid absorbing member that sits inside the collection container. 
     Other embodiments of the invention include a waste fluid collection container having a floor having a plurality of cylindrical studs thereon. The container also includes a wall located along said periphery and attached to and surrounding the floor. The container further includes a fluid absorbing member that sits inside the collection container. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments will be described in detail herein with reference to the following figures in which like reference numerals denote like elements and wherein: 
     FIG. 1 is a schematic top plane view of an embodiment of a waste fluid collection receptacle; 
     FIG. 2 is a cross section of an embodiment of the waste ink receptacle of FIG.  1 . 
     FIG. 3 is a schematic top plane view of an embodiment of a waste fluid collection receptacle having radially symmetric ridges on its floor; 
     FIG. 4 is a schematic top plane view of an alternative embodiment of a waste fluid collection receptacle of the present invention; 
     FIG. 5 is a cross section of an embodiment of the waste ink receptacle of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     While the present invention will be described with reference to specific embodiments thereof, it will be understood that the invention is not to be limited to these embodiments. On the contrary, it is intended that the present invention cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. Other aspects and features of the present invention will become apparent as the description proceeds, wherein like reference numerals have been used throughout to designate identical elements. It is further noted that all references cited in this specification, and their references, are hereby incorporated by reference where appropriate for relevant teachings of additional or alternative details, features, and/or technical background. 
     The invention is a new design for a waste fluid collection container or receptacle. One specific use of the container is for collecting waste ink in an ink jet printer. For examples of ink jet printers, refer to U.S. Pat. Nos. 5,432,538 and 6,130,684, the disclosures of which are totally incorporated herein by reference. These patents are only meant to give examples of types of ink jet printers and the embodiments of the invention disclosed below are not limited to use with the printer embodiments disclosed therein. 
     FIG. 1 illustrates an embodiment of the waste ink collection container of the present invention. It includes a tray  100  having a floor  102  and a surrounding wall  104 . The general shape of the periphery of the floor is not important and the particular geometry of the border of the floor  102  shown in FIG. 1 should not be considered limiting. This particular shape works well in some printers, but the shape of an ink collection tray will be different depending on the particular size, shape, and configuration of the machine in which it is used. The embodiment shown in FIG. 1 also includes an absorbent pad  110  placed inside the tray. 
     In embodiments, the wall  104  is connected to the floor along the floor&#39;s periphery. The location of the wall  104  does not have to exactly coincide with the periphery of the floor  102 . For example, the wall may be located a distance, such as an inch, inward from the edge of the floor. It is there to prevent ink from seeping out of the tray. The wall and floor together define a volume in which to contain ink ejected during either a priming or a spitting operation. 
     In embodiments, the tray floor has a plurality of elongated raised ridges  106  that extend outward from a central area  108 . In embodiments, the ridges  106  are molded into and are integral and one-piece with the bottom of the tray. The ridges  106  form flow channels between the pad  110  and the floor  102 . The channels increase the spread of ink through capillary action, thereby exposing a larger surface area of the pad to ink. Exposing more surface area of the pad to the ink increases the amount of ink absorbed by the pad. 
     In embodiments of the tray for use in ink jet printers, the ridges  106  are approximately 0.6 mm high and 2.0 mm wide. These dimensions can and likely would be different for use in different ink jet printers or other devices producing waste fluid. The dimensions depend upon multiple factors including, but not limited to, the size of the tray, the density of the ridges, the height of the tray, and the weight of the pad. Generally, the ridges should not be too high or the capillary channels formed will be too large to be effective. In embodiments, it was found that a height much larger than 1 mm would not be as effective. If the ridges are too short, they can be difficult to mold and their effectiveness can be compromised as the pad  110  might conform to the gaps and choke off the capillary channels. For the ink jet printers in which these trays were tested, ridges much smaller than 0.5 mm would not be as effective. With respect to the width of the ridges  106 , they should be wide enough for easy molding. 
     In embodiments, the majority, if not all, of the ridges  106  do not extend radially outward from the central area  108 . In other words, if the ridges  106  were extended inward, they would not all pass through a common center point of the central area  108 . In some cases, radial ridges may not be as effective as non-radial ridges. However, in embodiments where the tray is symmetrical, such as in FIG. 3, radial ridges might be used. 
     The central area  108  is useful in creating flow channels down each rib. In embodiments, the area used was approximately 27 mm in diameter, though a range of 25 to 30 mm should be effective. As with the ridges  106 , the diameter of the area can and will vary depending on the size of the tray. 
     FIG. 2 illustrates a cross section of the embodiment shown in FIG.  1 . The absorbent member or pad  110  has a hole  112  cut through it. The hole is located so that when the pad is placed in the tray, the hole is positioned over the central area  108  from which the raised ridges  106  extend. In embodiments, the absorbent pad  110  is shaped to fit the contours of the ink tray  100 . The pad of absorbent material absorbs the ink and is partially exposed to the atmosphere, so that the liquid portion of the ink absorbed therein evaporates maintaining adequate ink storage volume for repeated subsequent cycles of priming and nozzle clearing droplet ejections. Additionally, opening the hole up in the bottom layer increases the surface area for the ink to spread into the wall of the pad, local to the waste tube. In embodiments, the absorbent pad  110  is made of felt. 
     When the collection container is in use in a machine, ink is deposited into the container from above through hole  112 . In embodiments, the hole has a diameter of approximately 13 mm. The interior wall of the hole may absorb some ink as it enters the hole, but the majority will contact the floor in the central area  108 . Here it begins to seep along the floor  102  between the absorbing pad  110  and the floor. Depending on the amount of ink being deposited, the area could begin to fill, in which case more ink would be absorbed through the interior wall of hole  112 . 
     The radial ridges  106  enhance the spreading of the ink across the floor  102 . The ink spreads via the corners between the ridges  106  and the floor  102 . This exposes a greater portion of the surface area of the absorbing pad  110  to the ink. Because the ink contacts more of the surface area of the pad  110 , a greater volume of the absorbing pad can be used before the pad needs to be discarded and replaced. 
     As the absorbent material needs to be at least partially exposed to the atmosphere, most embodiments will not include a lid or other covering, although one can place a lid with a hole cut in it over the top of the receptacle. The hole would be required to admit ink into the collection container. If a covering or lid is used in conjunction with the present invention, it can be perforated so that water may evaporate out of the absorbent pad. The covering may also be designed to only partially cover the pad so as to expose a portion of its surface to the atmosphere. 
     FIGS. 4 and 5 show another embodiment of a waste ink collection container. It also includes a tray  200  having a floor  202  and a surrounding wall  204 , the particular geometry of which is not important. When the tray is in use in a machine, we can use an absorbent pad  210  similar to or the same as the one that is used with the radial ridge tray  100 . However, instead of ridges in the floor, the floor includes protrusions  206 . In embodiments, these protrusions  206  are pin fins or cylindrical studs. The protrusions or studs  206  allow ink to spread over the floor before being absorbed by the pad  210 . In embodiments, the studs are approximately 2-3 mm in diameter and approximately 0.5-1.0 inches high. 
     In the embodiment depicted in FIGS. 4 and 5, the pins are shown laid out in rows and columns. However, they do not have to be in a linear or uniform pattern. There are a myriad number of ways to arrange the studs on the floor of the tray and the pattern shown in FIGS. 4 and 5 should not be considered limiting. There is also no central flat area similar to the central area  108  in the ridge embodiment. This is primarily because the ridged embodiment uses capillary action and flow channels. For the embodiment of FIGS. 4 and 5, having a central flat area would probably not offer a great advantage to the user. However, there is no reason why a central flat area could not be included in tray  200 , and its absence should not be considered limiting. 
     Ink is still deposited into the container from above through a hole  212  in pad  210 . The studs enhance the spreading of the ink across the floor  202 , thus enabling the ink to contact a greater portion of the surface area of the absorbing pad  210 . This in turn allows use of a greater portion of the absorbing pad. 
     Although the primary embodiments discussed in this description have been directed toward ink jet printers, it is also expected that this tray design may have uses other than in printers. The improved absorption observed because of the ridges can have uses in the collection of other fluid waste products such as, for example, oil and the exact composition of the absorbent pad may change based on what particular fluid was being collected. 
     While the present invention has been described in connection with a preferred embodiment thereof, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.