Patent Publication Number: US-9409396-B2

Title: Ink jet print head protective guide system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 14/500,453, filed Sept. 29, 2014, now allowed, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present teachings relate to the field of ink jet printing devices and, more particularly, to a print head nozzle plate protection system. 
     BACKGROUND 
     Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet print heads can include the use of thermal ink jet technology, piezoelectric technology, or electrostatic technology. Each of these technologies include the ejection of ink drops from a plurality of nozzles within a nozzle plate. 
     Damage to the print heads, and more particularly the nozzle plate, can result from physical contact with other objects, including the print medium receiving the ink drops. For example, a print medium such as a paper sheet or other types of porous hydrophilic substrates can curl from absorption of ambient moisture, from improper storage or loading, or from moisture incurred from marking the sheet with aqueous ink. As the curled leading edge of the print medium enters the print area, the print medium can contact and damage the nozzle plate. Depending on the printer, replacement of a damaged print head is very expensive resulting from the cost of the print head itself, downtime of the printer, and labor costs incurred during replacement and/or repair. 
     A structure that reduces or eliminates damage to print heads from contact with the print medium or other structure would be desirable. 
     SUMMARY 
     The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, nor is it intended to identify key or critical elements of the present teachings, nor to delineate the scope of the disclosure. Rather, its primary purpose is merely to present one or more concepts in simplified form as a prelude to the detailed description presented later. 
     In an embodiment, a printer can include a print head comprising a nozzle plate. The nozzle plate can include a nozzle array comprising a plurality of nozzles arranged in a plurality of subarrays, and a plurality of intranozzle areas devoid of nozzles, wherein each intranozzle area is positioned between two adjacent subarrays from the plurality of subarrays. The printer can further include a print head protection guide, including a frame and a plurality of cross members attached to the frame and aligned with the plurality of intranozzle areas between each subarray. 
     In another embodiment, a method for operating a printer can include aligning a plurality of print head protection guide cross members with a plurality of intranozzle areas between a plurality of nozzles of a print head nozzle plate, wherein the plurality of intranozzle areas are devoid of nozzles, ejecting an ink from the plurality of nozzles onto a print medium while the plurality of print head protection guide cross members are aligned with the plurality of intranozzle areas, wherein the plurality of print head protection guide cross members protect the print head nozzle plate from physical contact with the print medium, and moving the plurality of print head protection guide cross members from a first position proximate the nozzle plate to a second position away from the nozzle plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present teachings and together with the description, serve to explain the principles of the disclosure. In the figures: 
         FIG. 1  is a plan view of a print head structure including a nozzle plate in accordance with an embodiment of the present teachings; 
         FIG. 2  is a plan view, and  FIG. 3  is a cross section along  3 - 3  of  FIG. 2 , of a protective guide system in accordance with an embodiment of the present teachings; 
         FIG. 4  is a plan view of the print head structure of  FIG. 1  and the protective guide system of  FIGS. 2 and 3  during use; 
         FIG. 5  is a side view, and  FIG. 6  is an end view, of a printer including a marking module having a plurality of print heads during printing in accordance with various embodiments of the present teachings; 
         FIG. 7  is an end view of a printer, wherein the protective guide system is retracted from the nozzle plate; and 
         FIG. 8  is an end view of a printer assembly, wherein the protective guide system is rotated away from a print area. 
     
    
    
     It should be noted that some details of the FIGS. have been simplified and are drawn to facilitate understanding of the present teachings rather than to maintain strict structural accuracy, detail, and scale. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the present teachings, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     As used herein, unless otherwise specified, the word “printer” encompasses any apparatus that performs a print outputting function for any purpose, such as a digital copier, bookmaking machine, facsimile machine, a multi-function machine, electrostatographic device, etc. Unless otherwise specified, the word “polymer” encompasses any one of a broad range of carbon-based compounds formed from long-chain molecules including thermoset polyimides, thermoplastics, resins, polycarbonates, epoxies, and related compounds known to the art. Unless otherwise specified, a “print medium” includes any surface that receives ink during printing. The print medium may be the terminal location of the ink or an intermediate surface that is used to subsequently transfer the ink to the terminal location, such as an intermediate transfer belt or roller. The print medium may be porous, nonporous, cellulosic, polymeric, fabric, metallic, etc. 
     The present teachings include a protective guide system that can reduce or eliminate damage to the print head nozzle plate resulting from physical contact with a print medium or another structure. The protective guide system protects print head structures from physical contact with objects such as a print medium by providing a contact barrier that reduces the likelihood of physical contact between the nozzle plate and another object. 
       FIG. 1  is a plan view of a print head  10  including a print head nozzle plate  12  in accordance with an embodiment of the present teachings. The nozzle plate  12  includes a plurality of nozzles (i.e., a nozzle array including a plurality of nozzles)  14  through the nozzle plate  12  from an ink supply side to an ink ejection side of the nozzle plate  12 . The nozzle array  14  is arranged as a plurality of nozzle subarrays  14 A- 14 D.  FIG. 1  depicts four nozzle subarrays  14 A- 14 D for illustration, but a nozzle array  14  may include two or more subarrays of nozzles (i.e., jets or apertures). 
     In  FIG. 1 , the plurality of nozzles  14  in each subarray  14 A- 14 D are arranged to have a perimeter shaped as an isosceles trapezoid having two sides, a longer base, and a shorter base as depicted, with each subarray  14 A- 14 D separated from at least one adjacent subarray by an intranozzle area (i.e., an intranozzle spacing)  16 . Each intranozzle area  16  is located within the boundary of the nozzle array  14  and between adjacent nozzle subarrays  14 A- 14 D. Each intranozzle area  16  between the subarrays  14 A- 14 D is devoid of (i.e., free from) nozzles  14 . The intranozzle areas  16  between each spaced subarray  14 A- 14 D result, in part, by forming every second subarray in an inverted orientation relative to the nozzle plate  12 , and spacing each subarray  14 A- 14 D from an adjacent subarray by a width of the intranozzle area  16 . For example, as depicted in  FIG. 1 , the longer bases of trapezoidal-shaped subarrays  14 A,  14 C are located (i.e., oriented) toward a first edge  18 A of the nozzle plate  12 , while the longer bases of trapezoidal-shaped subarrays  14 B,  14 D are located toward a second edge  18 B of the nozzle plate  12 , where the second edge  18 B is opposite the first edge  18 A. As depicted by dashed lines within the intranozzle areas  16  in  FIG. 1 , a midline of each intranozzle area  16  between each subarray  14 A- 14 D intersects the first edge  18 A to form an acute angle, wherein the acute angle may be from about 10° to about 30°, or from about 15° to about 25°, or about 22°. This angle is also the interior acute angle formed by the longer base and each side of each trapezoidal-shaped subarrays  14 A- 14 D. The width of each intranozzle area  16  between each subarray  14 A- 14 D may be from about 1 mm to about 4 mm, or from about 1.5 mm to about 3.5 mm, or from about 2 mm to about 3 mm. 
     Providing the plurality of subarrays  14 A- 14 D to be shaped as an isosceles trapezoid as depicted in  FIG. 1  allows, for example, a lateral space provided by the intranozzle area  16  that is devoid of nozzles between each subarray  14 A- 14 D. The angled intranozzle areas  16  allow for continuous printing across the width “W” of the nozzle array  14  as the print medium  52  ( FIG. 5 ) passes the nozzle plate  12  in the print direction “D.” The nozzle array  14  has an actual print width of “W” as depicted and defined by the outermost nozzles at either end of the nozzle array  14 . However, the print width W may not allow for sufficient ink coverage at the ends of the nozzle array  14  and may result in gaps in a solid ink pattern. In other words, the ends of the nozzle array  14  will not print at the rated print resolution. The nozzle array  14  may therefore have an effective print width “EW” as depicted that allows printing a solid ink pattern at the rated resolution (for example, 600 dpi) with continuous ink coverage without gaps. For a specific printer, a nozzle plate  12  may have a print width W of from about 110 mm to about 120 mm, for example about 116 mm, and an effective print width EW of from about 100 mm to about 110 mm, for example about 108 mm, although other printers may have other print widths W, EW. 
     The physical gap between the nozzle plate  12  and the print medium  52  is typically minimized during printing so that any off-trajectory ink drop has minimal adverse effects on print quality. For example, as the distance between the print medium  52  and the nozzle plate  12  increases, an off-trajectory ink drop is dispensed further from its intended target location on the print medium  52 . Thus spacing between the print medium  52  and the nozzle plate  12  during printing may be very small, on the order of 1 mm. Print media  52  such as paper sheets or other types of porous hydrophilic substrates can curl from absorption of ambient moisture, from improper storage or loading, or from moisture incurred from marking the print medium with aqueous ink. A curl height may be several millimeters. As a curled print medium passes by the nozzle plate during printing, the print medium  52  can strike and damage the nozzle plate  12 . 
       FIG. 2  is a plan view, and  FIG. 3  is a cross section along  3 - 3  of  FIG. 2 , depicting a protective guide system  30  in accordance with an embodiment of the present teachings. The guide system  30  can include a frame  32  and a plurality of cross members (e.g., rods or wires)  34 . The frame  32  can have two longer sides  33  that intersect two shorter sides  35  to form a generally rectangular perimeter in plan view. In an embodiment, the frame  32  and plurality of cross members  34  may be manufactured from a single piece of rigid material, such as a single piece of metal or a rigid polymer using a molding process. In another embodiment, the frame  32  and each rigid cross member  34  may be manufactured separately, and the cross members  34  may be welded or brazed to the frame, or adhered to the frame  32  using an adhesive. In another embodiment, the cross members  34  can be a plurality of metal rods brazed, welded, or adhered to the frame  32 . In another embodiment, the cross members  34  may be a plurality of twisted cables mounted at each end to the frame  32 . In an embodiment, the cross members  34  may be formed by a single line or cable that weaves through holes in the frame  32  to provide the plurality of cross members  34 . The cross members  34  may have a round cross section as depicted in  FIG. 3 , or they may be square, rectangular, or oval in cross section. 
     Additionally, the cross members  34  may optionally physically contact the nozzle plate  12  during use. Physical contact between the cross members  34  and the nozzle plate  12  may allow for a closer spacing between the nozzle plate  12  and the print medium  52  during printing. In case physical contact occurs, the cross members  34  may optionally include a protective coating  36  (one coated cross member is depicted in  FIG. 3  for illustration), for example a using a polymer coating. The protective coating  36  can pad the cross members  34  to reduce or prevent wear to the nozzle plate  12  from contact with the cross members  34  during use of the protective guide system  30 . The cross members  34  can also be uncoated as depicted in  FIG. 3 . 
     A width or diameter (hereinafter, collectively, diameter) of each cross member  34  is less than the width of each intranozzle area  16  between each nozzle subarray  14 A- 14 D. Additionally, a diameter of each cross member  34  is less than the spacing between the print medium  52  and the nozzle plate  12  during printing. The width of each cross member  34  may be from about 0.2 mm to about 3.8 mm, or from about 1.25 mm to about 3.25 mm, or from about 1.75 mm to about 2.75 mm. Each cross member  34  forms an acute angle with the frame  32 , which can be the same angle as the acute angle formed by the midline of each intranozzle area  16  between each subarray  14 A- 14 D that intersects the first edge  18 A. As described above, this acute angle may be from about 10° to about 30°, or from about 15° to about 25°, or about 22°. This acute angle is also the interior acute angle formed by the longer base and each side of each trapezoidal-shaped subarray. 
     The guide system  30  further includes an attachment system that attaches the frame  32  and cross members  34  to another location of the printer, for example, to a printer marking transport frame  58  ( FIG. 5 ) or to a print head frame  60  ( FIG. 5 ). As depicted in  FIGS. 2 and 3 , the attachment system can include at least one pin or rod  38  attached to the frame  32  and at least one hole  69  within the marking transport frame  58  or the print head frame  60  that receives the pin. During use, the attachment system may allow the frame  32  and cross members  34  to retract away from the nozzle plate  12 . Retraction away from the nozzle plate  12  may be performed, for example, to clear a paper jam or to allow cleaning or other maintenance of the nozzle plate  12 . Cleaning may be necessary, for example, to remove ink residues from the nozzle plate  12 . Regular maintenance of the print head  10 , such as cleaning of the print head face, is also routinely performed. 
     It will be appreciated that forming intranozzle areas  16  that are excessively wide increases the difficulty of providing complete ink coverage onto a print medium across the entire nozzle array  14 , while forming intranozzle areas  16  that are too narrow results in an insufficient area to place a cross member  34  of a width that is sufficient to provide adequate protection of the nozzle plate  12 . 
       FIG. 4  is a plan view of the protective guide assembly  30  of  FIGS. 2 and 3 , and the print head  10  including the nozzle plate  12  of  FIG. 1 , during use. As depicted, the frame  32  can have a perimeter than extends outside a perimeter of the nozzle plate  12 . 
       FIG. 5  is a side view, and  FIG. 6  is an end view, of the print head  10 , nozzle plate  12 , and guide assembly  30  including frame  32  and cross members  34  during printing of ink (e.g., ink drops)  50  onto a print medium  52  such as a paper sheet or transparency. In the  FIG. 6  end view, the frame  32  is depicted in partial cutaway to reveal the cross members  34  and the nozzle plate  12 . Ink  50  is supplied from a print head  10  or other ink feed mechanism. In an embodiment, the print medium  52  is transported to the print area using a transport mechanism  56  such as the belt depicted, or by more than one belt or a series of rollers (not depicted for simplicity). The belt  56  may be supported and actuated by a marking transport frame  58 , and a mechanical assembly within the marking transport frame  58 , as known in the art.  FIG. 5  depicts the print medium  52  within a print medium path between the nozzle plate  12  and the belt  56 . The print medium path includes the path through which the print medium is transported from a supply tray to an output tray, and includes the location between the print head  10  and the transport mechanism  56  and the print area directly between the nozzle plate  12  and the transport mechanism  56 . 
     The print head  10  may be supported by a print head frame  60  of a marking module  61 . In an embodiment, a hole  62  in the print head frame  60  receives the pin  38  that is attached to the guide frame  32  as described above. In an embodiment, the pin  38  can be fully extracted from the hole  62  in the print head frame  60  to remove the guide frame from between the belt  56  and the nozzle plate  12 , thereby providing access to clean the nozzle plate  12  or to clear a paper jam. 
     In another embodiment, a pin  64  in the guide frame  32  is attached to the marking transport frame  58  using a marking transport frame attachment. The marking transport frame attachment can include, for example, a mount  66  having a hole  69  through which the pin  64  extends. The pin  64  may be slid through the hole in the mount  66 , with the pin  64  being held in place by a fastener, for example, a friction fastener  68 , such as a recessed screw or thumb screw that holds the pin  64  in place. The friction fastener  68  can be loosened so that the pin  64  is released. When in use, the friction fastener  68  is tightened and holds the frame  32  and cross members  34  close to (i.e., proximate) the nozzle plate  12  in a first position for printing. In the first position ( FIGS. 5 and 6 ), the cross members  34  are positioned for printing directly between the nozzle plate  12  and the transport mechanism  56 , close to or physically contacting the nozzle plate  12 . When released, the guide frame  32  and cross members  34  may be retracted vertically away from the nozzle plate  12  and toward the transport mechanism  56  into a second position as depicted in the end view of  FIG. 7 . In the second position, the cross members  34  are still positioned directly between the nozzle plate  12  and the transport mechanism  56 , but printing is not available when the print head protection guide  30  is in this position. After retracting the print head protection guide  30  away from the nozzle plate into the second position, the guide frame  32  and cross members  34  may be rotated horizontally away from the nozzle plate  12 , the transport mechanism  56 , and the print area using the pin  64  as an axis point into a third position as depicted in  FIG. 8 . In the third position, the cross members  34  are not positioned directly between the nozzle plate  12  and the transport mechanism  56 . When the print head protection system  30  including the guide frame  32  and the cross members  34  are in the third position, the nozzle plate  12  is exposed for cleaning and/or other maintenance. Thus the print head protection guide  30 , including the frame  32  and the cross members  34 , are configured to be positioned for printing close to, or physically contacting, the nozzle plate in the first position, retracted away from the nozzle plate  12  into a second position, and rotated away from the nozzle plate  12  into a third position. After cleaning and/or other maintenance, the print head protection system  30  is rotatable about the pin  64  from the third position into the second position, and can be advanced toward the nozzle plate  12  into the first position for printing. During use, the protective guide system  30  is positioned between the nozzle plate  12  and the print medium path within the print area directly underneath the nozzle plate  12 . As depicted in  FIGS. 5 and 6 , the protective guide system  30  is positioned between the nozzle plate  12  and the belt  56 . The plurality of cross members  34  of the protective guide system  30  are aligned with the plurality of intranozzle areas  16  between each nozzle subarray  14 A- 14 D so that ink can be ejected from the plurality of nozzles  14  and onto the print medium. Because the cross members  34  are aligned with the intranozzle areas  16  during printing, the cross members do not block or otherwise obstruct the ink as it is ejected from the nozzles  14 , yet complete ink coverage across the print medium  52  can be maintained. 
     As the print medium  52  is positioned between the nozzle plate  12  and the transport medium  56  within the print area, a height of the print medium, particularly the height of a curled print medium, may be greater than the distance between the nozzle plate  12  and the location of an uncurled print medium. Without the protective guide system  30 , the curled print medium can physically contact and damage the nozzle plate  12 . During use, the protective guide system  30  guides and deflects the curled print medium away from the nozzle plate  12  to prevent physical contact between the print medium  52  and the nozzle plate. The face of the nozzle plate  12  including the nozzles  14  from which ink drops  50  are ejected during printing are particularly protected by the cross members  34 . 
     The protective guide system  30  can also reduce or prevent certain types of paper jams, for example, jams resulting from lead-edge paper stubbing. The protective guide system  30  deflects any non-flat media away from the jets eliminating contact between the print media and the ink jet head surface. The guide frame remains in place allowing the guide system of wires (i.e., cross members  34 ) to be fixed while allowing the ink jet head  10  to move up and over to be cleaned without interfering with the wires. 
     A printer in accordance with an embodiment of the present teachings can be operated by aligning the plurality of print head protection guide cross members  34  within the frame  32  with the plurality of intranozzle areas  16  between the plurality of nozzles  14  of the print head nozzle plate  12 . The plurality of intranozzle areas  16  are devoid of nozzles  14 . Ink  50  can be ejected from the plurality of nozzles  14  onto the print medium  52  while the plurality of print head protection guide cross members  34  are aligned with the plurality of intranozzle areas  16 . The plurality of print head protection guide cross members  34 , which may or may not physically contact the nozzle plate  12 , protect the print head nozzle plate  12  from physical contact with the print medium  52 . In an embodiment, the plurality of print head protection guide cross members  34  and frame  32  may be moved from a first position proximate the nozzle plate  12  (e.g., as depicted in  FIGS. 5 and 6 ) to a second position away from the nozzle plate  12  (e.g., as depicted in  FIG. 7 , or as depicted in  FIG. 8 ). 
     In an embodiment, the plurality of print head protection guide cross members  34  and frame  32  may be retracted vertically away from the nozzle plate from a first position proximate the nozzle plate  12  (e.g., as depicted in  FIGS. 5 and 6 ) to a second position away from the nozzle plate  12  (e.g., as depicted in  FIG. 7 ). From the second position, the cross members  34  and frame  32  may further be moved horizontally away from the nozzle plate  12  from the second position to a third position as depicted in  FIG. 8  to provide access to the nozzle plate  12 . 
     To reduce or prevent unwanted deflection of the ink drops  50  away from the target trajectory during printing resulting from, for example, electrostatic buildup on the protective guide system  30  and the associated reduction in print quality, the frame  32  and/or cross members  34  may be grounded  39  to an electrical ground as depicted in  FIG. 2 . Generally, neither the frame  32  or the cross members  34  will be connected to power and thus provide a physical barrier for the nozzle plate for protection from contact with other structures rather than an electrical barrier. 
     It will be appreciated that the FIGS., for example  FIGS. 5 and 6 , may not be to scale and have been drawn to facilitate understanding of the present teachings. Additionally, a structure in accordance with the present teachings may include additional structures that have not been depicted for simplicity, while various depicted structures may be removed or modified. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present teachings are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any and all sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less than 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc. 
     While the present teachings have been illustrated with respect to one or more implementations, alterations and/or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it will be appreciated that while the process is described as a series of acts or events, the present teachings are not limited by the ordering of such acts or events. Some acts may occur in different orders and/or concurrently with other acts or events apart from those described herein. Also, not all process stages may be required to implement a methodology in accordance with one or more aspects or embodiments of the present teachings. It will be appreciated that structural components and/or processing stages can be added or existing structural components and/or processing stages can be removed or modified. Further, one or more of the acts depicted herein may be carried out in one or more separate acts and/or phases. Furthermore, to the extent that the terms “including,” “includes,” “having,” “has,” “with,” or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one of ” is used to mean one or more of the listed items can be selected. Further, in the discussion and claims herein, the term “on” used with respect to two materials, one “on” the other, means at least some contact between the materials, while “over” means the materials are in proximity, but possibly with one or more additional intervening materials such that contact is possible but not required. Neither “on” nor “over” implies any directionality as used herein. The term “conformal” describes a coating material in which angles of the underlying material are preserved by the conformal material. The term “about” indicates that the value listed may be somewhat altered, as long as the alteration does not result in nonconformance of the process or structure to the illustrated embodiment. Finally, “exemplary” indicates the description is used as an example, rather than implying that it is an ideal. Other embodiments of the present teachings will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the present teachings being indicated by the following claims. 
     Terms of relative position as used in this application are defined based on a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “horizontal” or “lateral” as used in this application is defined as a plane parallel to the conventional plane or working surface of a workpiece, regardless of the orientation of the workpiece. The term “vertical” refers to a direction perpendicular to the horizontal. Terms such as “on,” “side” (as in “sidewall”), “higher,” “lower,” “over,” “top,” and “under” are defined with respect to the conventional plane or working surface being on the top surface of the workpiece, regardless of the orientation of the workpiece.