Electronics for Imaging Issued Patent for Ink Jet Printer

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Date: Tuesday April 16, 2013 08:42:50 am
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    Electronics for Imaging Issued Patent for Ink Jet Printer

    By a News Reporter-Staff News Editor at Electronics Newsweekly — Electronics for Imaging, Inc. (Foster City, CA) has been issued patent number 8408676, according to news reporting originating out of Alexandria, Virginia, by VerticalNews editors.

    The patent’s inventors are Edwards, Paul Andrew (Ypsilanti, MI); Hennessy, John (Grosse Pointe Park, MI); Bruck, Frank (Ypsilanti, MI).

    This patent was filed on April 23, 2012 and was published online on April 2, 2013.

    From the background information supplied by the inventors, news correspondents obtained the following quote: "The statements in this section merely provide background information related to the present teachings and may not constitute prior art.

    "Ink jet print heads tend to be sensitive to bumping or jolting. This relates to the fact that there is very sensitive control on the ink meniscus at the nozzle orifice. This bumping and jolting can occur when the head is moved up and down for cleaning or to re-thread the substrate. If a print head is jolted too much, then the meniscus can be lost and air becomes entrapped into the nozzle orifice resulting in missing jets. Loss of jets in a single pass printing activity can cause print quality defects, which are generally not acceptable. This is worse in some print heads, such as the grayscale print heads, which are very sensitive to loss of jets when jolted or vibrated, but occurs to some extent in all ink jet heads.

    "Little has been done in the past to adequately resolve this problem. Systems tend to be fitted with air driven or manual actuators which move the print heads up and down. This technique does tend to improve the control of head movement over a more manual process, but has proven to be insufficient. Air actuators are especially vulnerable to reduced motion quality with time.

    "Separate from the above issue, ink jet print systems often rely upon the extremely precise placement of their print heads. If the print heads can be accurately aligned and secured, it is then possible to set two heads in relation to each other such that the nozzle ports are ‘interleaved’. This interleaved configuration results in a doubling of the print dot density, so that two heads, each with 150 dots per inch (DPI) resolution, can print like a single 300 DPI print head.

    "Aside from achieving the interleaved configuration described above, print heads are commonly placed side by side to gain additional print width. Print heads can be ‘stitched’ together in this manner to create wide format printers made up of a series of narrow heads that have been stitched together. The accuracy with which the heads are stitched together must also be high as it is not generally acceptable to have either a gap or and overlap in the printed image. For these reasons and others around print quality, the ability to secure and align print heads in the system may be important to functionality.

    "Previous work to interleave and stitch print heads together have centered on a trial and error methodology, whereby prints are generated and visually checked (under a low power microscope) for interleave and stitch accuracy. If the prints show a misalignment condition, the heads are loosened, moved to a new location, and re-tightened. This method is repeated until all heads are interleaved and stitched properly. It should be appreciated that this process is very time consuming, since moving one head necessitates moving all other heads as their locations are interrelated. Other methods that use an optical alignment tool to interleave two heads together use non-reversible adhesives to bond the heads together. This method has the inherent risk such that if the alignment is not accurate after the bond is set, no corrections can be made, and thus, the heads must be scrapped.

    "Still further, industrial ink jet printing systems often rely on a smooth support surface to support the substrate in the web zone where printing is being done (where the ink jets are jetting). This requirement is to maintain the optimized distance between the substrate and the print heads.

    "Print platens are commonly designed and manufactured to be smooth, flat surfaces, slightly wider than the substrate itself, and long enough to accommodate the print zone length. The substrate is transported to and from the print platen by a series of web rollers incorporated into the printer.

    "During printing, some substrates tend to curl up along the edges. This is especially true if the substrate is made of multiple layers, e.g., a pressure sensitive adhesive label stock with a printable top surface, adhesive layer, and a removable backing paper. Such substrates tend to curl at the edges regardless of increasing speed or tension. It should be readily appreciated that this curling action changes the physical position of that portion of the substrate in relation to the print heads, which results in poor print quality along the edges or significant reduction in printable width for a given substrate width.

    "Conventional designs of print platens have primarily centered on full surface flat plates or full surface curved surfaces. However, flat platen designs do not address the curled substrate issue. Conversely, full surface curved platens are cost prohibitive because of the challenging machining that is required to manufacture.

    "Finally, the sustainability, jetting quality, and ultimate print quality of the ink used in digital ink jet printing are affected when the temperature of the ink is not accurately controlled prior to entering the print head. Although methods of thermal conditioning have been used before, the techniques according to the present teachings show significant improvement.

    "Previous work to control the temperature of the ink was mostly limited to the use of the water jacket or an electric heater attached to a print head. However, such techniques failed to provide effective and reliable results."

    Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors’ summary information for this patent: "According to the principles of the present teachings, an ink jet printer is provided having a print head that is accurately positionable in response to servo control. The present teachings seek to eliminate the problem of lost jets due to the jolting of print heads when they are moved to the non printing or cleaning position during operation of the printing system by accurately and smoothly moving the print head.

    "The present teachings are superior to those methods previously used because they provide for significantly greater control over the entire range of movement of the print head, especially the key periods of acceleration and deceleration when the head is most susceptible to losing the nozzle meniscus. The system is also less prone to issues related to variability in air pressure and wear in components leading to rapid changes in acceleration. The system also allows for the accurate and rapid setting of print head-to-substrate gap (or print head-to-platen gap).

    "In some embodiments, the platen is moved down and out of the way while maintaining the print head in a stationary position, which solves the loss of jets due to head motion by allowing the heads to remain still while the platen is moved. The present teachings are superior to the prior art in that they ensure that there is no unacceptable head motion or vibration which can cause lost jets. In a manufacturing process this translates to considerably improved machine set up times and reduction in lost time for maintenance activities. The ability to be able to precisely locate the position of the platen beneath the print head also allows for ease of optimization of print distance when switching substrates. That is, with DOD ink jet technology, the distance of the print head to the substrate is quite small (around 1 mm) and needs to be accurately controlled.

    "In some embodiments, an apparatus and method for configuring, securing, and/or aligning multiple ink jet print heads on a printing machine is provided. The present teachings are superior to the methods previously used because they allow for the fine and accurate adjustment of print heads in a digital print system, without the extended trial and error method, or the risk of a bonded poor alignment. The set up time when installing new print heads is greatly reduced, and there is no risk of scrapping expensive heads of the optically aligned heads print with interleave variance.

    "Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings."

    For the URL and additional information on this patent, see: Edwards, Paul Andrew; Hennessy, John; Bruck, Frank. Ink Jet Printer. U.S. Patent Number 8408676, filed April 23, 2012, and published online on April 2, 2013. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=100&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=4992&f=G&l=50&co1=AND&d=PTXT&s1=20130402.PD.&OS=ISD/20130402&RS=ISD/20130402

    Keywords for this news article include: Electronics for Imaging Inc.

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