Abstract:
A baffle for use in a printer to protect a printhead from particulates associated with a printing medium. The baffle including a member, incorporated within the printer, that is positioned below the printing medium and above the printhead. The member having a top surface that is angled and extends a width of the printing medium and an adhesive material disposed on the angled top surface, the adhesive material. The angled top surface being positioned to generally face toward the printing medium to trap the printing medium particulates on the adhesive material of the angled top surface.

Description:
This is a divisional application of U.S. patent application Ser. No. 11/167,133, filed on Jun. 28, 2005, the contents of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     All references cited in this specification, and their references, are incorporated by reference herein where appropriate for teachings of additional or alternative details, features, and/or technical background. 
     Disclosed in the embodiments herein is a system for protecting the face of a printhead, in particular a solid ink jet printhead printing on an image transfer member, from contaminants. Such system comprises a sticky baffle placed in close proximity to the surface of an image transfer surface superior to the printhead. 
     For printing in a solid-ink printer, the simplest method of producing an output image is to propel droplets of ink onto a piece of paper to directly print the image onto the paper, i.e., a process known as direct printing. However, direct printing has many disadvantages. First, the head to paper gap must be adjusted for different media in order to control drop position. Second, there is the well-known paper hand-off problem between the rollers that guide the paper, because of the large size of the head. Third, there is a concern that head reliability will decrease because the paper is near the head. Also, to maximize print speed, many direct print architectures deposit the image bidirectional, which introduces image artifacts and color shifts. These problems are addressed with an offset, or indirect printing process. In this process, the ink is first applied to a rotating drum or other intermediate support surface and then transfixed off onto the paper wherein the ink goes on hot and then is fused. Therefore, a single drum surface transfers the image, spreads the ink droplets, penetrates the ink into the media, and controls the topography of the ink to increase paper gloss and transparency haze. 
     The process requires a delicate balance of drum temperature, paper temperature, transfix load, drum and transfix roller materials and properties thereof in order to achieve image quality. 
     To solve some of the above stated problems, ink jet printing systems have utilized intermediate transfer ink jet recording methods, such as that disclosed in U.S. Pat. No. 5,389,958. The intermediate transfer surface is applied by a wicking pad that is housed within an applicator apparatus. Prior to imaging, the applicator is raised into contact with the rotating drum to apply or replenish the liquid intermediate transfer surface. 
     Once the liquid intermediate transfer surface has been applied, the applicator is retracted and the print head ejects drops of ink to form the ink image on the liquid intermediate transfer surface. The ink is applied in molten form, having been melted from its solid state form. The ink image solidifies on the liquid intermediate transfer surface by cooling to a malleable solid intermediate state as the drum continues to rotate. When the imaging has been completed, a transfer roller is moved into contact with the drum to form a pressurized transfer nip between the roller and the curved surface of the intermediate transfer surface/drum. A final receiving substrate, such as a sheet of media, is then fed into the transfer nip and the ink image is transferred to the final receiving substrate. 
       FIG. 1  (prior art) is an overall perspective view of an offset phase change ink jet printing apparatus, generally indicated by the reference numeral  1 . An example of an offset phase change ink jet printer is disclosed in U.S. Pat. No. 5,389,958. 
       FIG. 3  (prior art) illustrates the inner works of solid ink jet systems that may be employed in the housing shown in  FIG. 1  employing an image transfer drum. 
     Referring to  FIG. 3 , there is shown a print head  11  having ink jets supported by appropriate housing and support elements (not shown) for either stationary or moving utilization to deposit ink droplets in image configuration onto an intermediate transfer surface  12 . 
     For hot melt or solid ink based systems, the ink utilized is preferably initially in solid form and then changed to a molten state by the application of heat energy to raise the temperature from about 85 degrees to about 150 degrees centigrade. In various embodiments, the temperature may be lower or higher, but this range is preferred. Elevated temperatures above this range may cause degradation or chemical breakdown of inks currently in use. The molten ink is then applied in raster fashion from ink jets in the print head  11  to the intermediate transfer surface  12  forming an ink image. The ink image is then cooled to an intermediate temperature and solidifies to a malleable state wherein it is transferred to a receiving substrate  28  such that the pixels are not spread and an initial matte finish is achieved. 
     The intermediate transfer surface  12  may be provided in the form of a drum, as shown in  FIG. 3 , but may also be provided as a web, platen, belt, band or any other suitable design. The drum  14  may be fabricated out of any metallic material and most preferably is made from aluminum and polished to a high gloss. The intermediate transfer surface may also be coated with an elastomer layer  8 , which defines a release surface. In addition, the intermediate transfer surface  12  may be coated with a liquid release layer applied to the drum  14  by contact with an applicator assembly  16 , such as a liquid impregnated web, wicking pad, roller or the like. By way of example, but not of limitation, applicator assembly  16  comprises a wicking roller or pad of fabric or other material impregnated with a release liquid for applying the liquid and a metering blade  18  for consistently metering the liquid on the surface of the drum  14 . Suitable release liquids that may be employed to coat the intermediate transfer surface  12  include water, fluorinated oils, glycol, surfactants, mineral oil, silicone oil, functional oils or combinations thereof. As the drum  14  rotates about a journalled shaft in the direction shown in  FIG. 3 , applicator assembly  16  is raised by the action of an applicator assembly cam and cam follower (not shown) until the wicking roller or pad is in contact with the surface of the drum  14 . The release liquid, retained within the wicking roller or pad is then deposited on the surface of the drum  14 . 
     The intermediate transfer surface  12  may be heated by an appropriate heater device  19 . The heater device  19  may be a radiant resistance heater positioned as shown or positioned internally within the drum  14 . In a preferred embodiment incorporating solid ink based ink jet technology, the heater device  19  may increase the temperature of the intermediate transfer surface  12  from ambient temperature to between 25 degrees to about 70 degrees centigrade or higher for receiving the ink from print head  11 . This temperature is dependent upon the exact nature of the liquid employed in the intermediate transfer surface  12  and the ink used and can be adjusted by providing an optimal temperature controller  40  in combination with a thermistor  42 . Ink is then applied in molten form from, for example, about 85 degrees to about 150 degrees centigrade to the exposed surface of the intermediate transfer surface  12  by the print head  11  forming an ink image  26 . The ink image  26  solidifies on the intermediate transfer surface  12  by cooling down to the malleable intermediate state temperature provided by heating device  19 . 
     After the ink image is created on the intermediate transfer surface, the image is then transferred to a receiving substrate  28 . A receiving substrate guide apparatus  20  may transport the receiving substrate  28 , such as paper or transparency, from a positive feed device (not shown) and guides it through a nip  29  formed between drum  14  and transfer roller  23 . Thus, opposing arcuate surfaces of the transfer roller  23  and the drum  14  forms the nip  29 . The transfer roller  23  may have a metallic core) preferably steel with an elastomer coating  22 . The drum  14  continues to rotate, entering the nip  29  formed by the transfer roller  23  with the curved surface of the intermediate transfer surface  12  containing the ink image  26 . The ink image  26  is then deformed to its image conformation and transferred to the receiving substrate  28  such that the pixels formed by the ink image on the receiving substrate are not spread creating an initial matte finish. The elastomer coating  22  on roller  23  engages the receiving substrate  28  on the reverse side to which the ink image  26  is transferred. 
     In this process, the ink image  26  is first applied to the intermediate transfer surface  12  of the rotating drum  14  and then transfixed off onto the receiving substrate  28  having a pixel image. Stripper fingers  25  (only one of which is shown) may be pivotally mounted to the imaging apparatus  10  to assist in removing any paper or other final receiving substrate  28  from the exposed surface of the intermediate transfer surface  12 . 
     Heater  21  may be used to preheat the receiving substrate  28  prior to the transfer of the ink image  26 . The thermal energy of the receiving substrate  28  is preferably kept sufficiently low so as not to melt the ink image upon transfer to the receiving substrate  28 . When the ink image  26  enters the nip  29  it is deformed to its image conformation and adheres to the receiving substrate  28  either by the pressure exerted against ink image  26  on the receiving substrate  28  or by the combination of the pressure and heat supplied by heater  21  and/or heater  19 . Heater  24  may be employed which heats the transfer roller  23 . Heater devices may also be employed in the paper or receiving substrate guide apparatus  20  and/or in the transfer and fixing roller  23 , respectively. The pressure exerted on the ink image  26  must be sufficient to have the ink image  26  transfer to the receiving substrate  28 . 
     A general problem in ink jet printers printing on an image transfer member, in particular solid ink jet printers or so-called phase change ink jet printers, is that the paper in its movement through the printer may introduce paper particle contamination into the inner machine environment where such contamination may reach the nozzle faces of the printheads, causing temporary or permanent jet deflections or outages.  FIG. 2  (prior art) shows a front plan view of an orifice plate  7  that forms part of an ink jet print head (not shown). An example of a suitable ink jet print head is found in U.S. Pat. No. 5,677,718. The orifice plate  7  includes multiple rows of multiple orifices  5 . The print head ejects ink from orifices  5  to create an image on an intermediate transfer surface (not shown), such as silicone oil. The image is then transferred to a final receiving medium, such as a sheet of paper. There is needed a low cost contamination abatement system which traps contaminants before they can reach the printhead. 
     REFERENCES 
     U.S. Pat. No. 5,389,958, commonly assigned, discloses a method and the apparatus for employing the method whereby an intermediate transfer surface of a layer of sacrificial liquid is applied to a supporting surface and a phase change ink is deposited on the liquid layer. The inked image is then transferred to a final receiving substrate. 
     U.S. Pat. No. 6,164,752, commonly assigned, discloses a method for purging an ink jet print head to clear ink jet orifices is provided. A purge cap forms a vacuum seal over the orifice plate of the print head. Multiple low pressure differential vacuum pulses are applied to the purge cap to remove debris and trapped air bubbles from the ink jet orifices. The low pressure pulses avoid cavitation inside the print head and reduce the amount of ink expelled during the purging process. 
     SUMMARY 
     Aspects disclosed herein include: 
     a baffle for use in a printer to protect a printhead printing on an image transfer member which then transfers the printing to a printing medium from particulates associated with the printing medium, the baffle comprising a structure configured to be positioned within the printer below the printing medium and above the printhead, and having a first adhesive surface facing generally toward the printing medium when positioned in the printer; 
     an ink jet printer comprising a baffle having a first adhesive surface, the baffle being positioned below the printing medium and above the printhead with the first adhesive surface facing generally toward the printing medium; and 
     a method for protecting an ink jet printhead in a printer utilizing an image transfer member to transfer the image onto substrate feed in a substrate path positioned superior to the ink jet printhead, the method comprising positioning a baffle having a first adhesive surface below the printing medium and above the printhead with the first adhesive surface facing generally toward the printing medium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various of the above mentioned and further features and advantages will be better understood from this description of embodiments thereof including the attached drawing figures wherein: 
         FIG. 1  shows a prior art ink jet printer in overall perspective view; 
         FIG. 2  shows a prior art orifice plate in an ink jet printhead in front plan view; 
         FIG. 3  shows a prior art cross-sectional diagrammatic illustration of an ink jet printer designed to print on an intermediate transfer member; 
         FIG. 4  shows a view similar to  FIG. 3 , but with a baffle mounted therein; and 
         FIG. 5  shows a view similar to  FIGS. 3 and 4 , but with a different baffle mounted therein. 
     
    
    
     DETAILED DESCRIPTION 
     In embodiments, there is disclosed printing medium baffle for protecting printheads printing on an image transfer member from particulates associated with the printing medium, the baffle comprising a structure configured to be positioned within a printer inferior to (i.e., below) the printing medium and superior (i.e., above) to the printhead, and having a first adhesive surface lying over the printhead when positioned in the printer. 
     In such embodiment, the structure may further comprise a second adhesive surface in close proximity to the image transfer member. The first and second adhesive surfaces may be different or the same, on the same side, or opposite one another. The structure may contain two surfaces angles with respect to each other. Such baffle embodiment may be used in an inkjet printer that may employ an image drum, or movable image transfer member such as an image web, for example, an image belt. The baffle may be generally positioned to be capable of trapping stray printing substitute particles and/or particles expelled or extending from a moving image transfer member. 
     In one embodiment, there is provided a stiff baffle placed in proximity to the surface of an intermediate transfer drum. The baffle is positioned so as to have an adhesive surface exposed below the paper or other substrate path running above the intermediate transfer drum. The top adhesive surface is positioned to shield the drum from particles raining down from above by capturing those particles as the paper or other substrate passes above the drum. The baffle may also have an adhesive surface positioned to capture particles traveling in the boundary layer around the drum when the drum is spinning and to capture any long fibers, etc., that may extend from the drum and contact the baffle. 
     In one embodiment, the baffle comprises a metal or plastic stock having adhesive applied to at least one surface. Adhesives remaining sticky or adherable over prolonged periods of time are usefully employed. For example, as found with double-sided sticky tape from Tel Pella, Inc. 
     As the abatement effect of such baffle system will decrease over time, in particular as the tacky collection surface becomes saturated with contaminants, it would be useful if the baffle contamination abatement system were renewable, either by incorporation of the system into a customer replacement unit, such as the drum maintenance cassette (which may be replaced every 10,000 to 30,000 prints), or by configuring the adhesive surface(s) of the baffle to be renewable. Incorporation of all or part of the abatement system into an existing “print process” customer replaceable unit ensures regular replacement. With proper replacement intervals, periodic renewal of the abatement system will prevent the decreased effectiveness associated with a particle-saturated collection surface, extending the initial reliability benefit of abatement throughout the printer&#39;s life. If the replacement interval of print-related customer replaceable units is less than the printer&#39;s life or the print interval during which the abatement system designates, then the combined customer replaceable unit ensures effective abatement and an associated reliability enhancement throughout the printer&#39;s life. 
     Now turning to  FIG. 4 , there is shown a cross-sectional view similar to  FIG. 3 , but with a baffle  70 . Surface  72  of baffle  70  may comprise adhesive material (not shown). The surface  74  generally opposite surface  72  may be devoid of adhesive material. Preferably the baffle  70  and at least its first adhesive surface  72  extend for the entire width (i.e., the direction perpendicular to  FIG. 4 ) of the printing medium (e.g., at least 11 inches for a printer designed to receive 11 inch wide paper). This helps to ensure that material falling from anywhere along the width of the medium may stick to the adhesive on surface  72 . 
     The angles of the surface  72  may be selected such that loose fibers from the printing medium or other such items on the surface of the drum  12  may contact the adhesive surface  72 . This facilitates removal such items from the drum  12  upstream of the printhead  11 . 
       FIG. 5  shows an alternative arrangement with a differently shaped baffle  80 . This baffle  80  has a first adhesive surface  82  similar to surface  72 . This surface captures particles falling down from the printing medium  28 . Additionally, a second adhesive surface  84  is provided. This second surface has an arcuate shape, is angled with respect to surface  82 , and conforms to the outer shape of drum  12 . This surface  84  is in close proximity to the drum  12  to allow particles, such as fiber strands from the printing medium  28 , to adhere to surface  84  upstream of the printhead  11 . 
     Like baffle  70 , baffle  80  and its surfaces  82  and  84  also preferably extend for the entire width of the printing medium  28 . 
     The baffle  70  may be optionally attached to the lower end portion of a upper exit paper guide of the printer. Such an attachment may be made by screws, a snap-fit connection, or by any other suitable means. It could also be attached by integrally forming it as part of the paper guide. However, any other suitable mounting or attachment may be used. 
     In either embodiment, a gap between the image transfer member (e.g., drum  12 ) and the baffle  70 ,  80  may be narrower than a gap between the image transfer member and the printhead  11 . This is desirable to prevent particles that could get between the printhead  11  and transfer member from falling downward to the gap between them, as the narrower gap between the baffle  70 ,  80  and the image transfer member restricts that from happening. 
     Also disclosed is a method for protecting an ink jet printer forming an image onto a substrate fed in a substrate path positioned above the ink jet printhead, positioning a baffle configured to have at least one adhesive surface such that an adhesive surface of the baffle is positioned below the substrate path and above the ink jet printhead in a manner to allow such adhesive to trap particles of substrate shed in the feed process. 
     While the invention has been particularly shown and described with reference to particular embodiments, it will be appreciated that variations of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.