Patent Publication Number: US-11383533-B2

Title: Composite dryer transport belt

Description:
BACKGROUND 
     Systems and methods herein generally relate to printers and printing equipment, and more particularly to a composite dryer transport belt used within printing equipment. 
     Various substances are used as marking material within printing devices, including wet and dry inks, dry powders (toners), etc. Further, such diverse marking materials can be applied in many different ways, including printing engines that contact the print media, printing engines that spray liquid marking material on the print media, print engines that electrostatically transfer the marking material to the print media, etc. These different marking materials are applied in such different manners in order to meet various goals such as a desired printing speed, a desired printing costs, etc. 
     One issue that is common among many different types of printers is the need to quickly and economically dry liquid marking materials without distorting either the pattern of the marking material or the underlying print media. Heaters and forced air devices (vacuum plenums used with vacuum belts, etc.) are often included as components in dryers of printing devices. 
     When vacuum belts are used as the transport belt through such printer dryers, the printed item can have highly visible image quality (IQ) defects in the forms of circles and lines in the process direction that correspond to the holes edges and belt edges. Such defects are caused by thermal conductivity and vacuum gradients created within the print media sheet between areas of the sheet that contact the heated belt and areas of the sheet that cover the vacuum holes or areas of the sheet that are beyond edges of the belt. 
     SUMMARY 
     Various apparatuses herein include, among other components a sheet feeder configured to feed print media, a print engine positioned to receive the print media from the sheet feeder and configured to apply marking material to the print media to create a printed item, a transport belt positioned to receive the printed item from the print engine and configured to move the printed item away from the print engine, a heater positioned adjacent to the transport belt and configured to heat the printed item on the transport belt, a vacuum plenum positioned adjacent to the transport belt and configured to draw air through the transport belt, etc. The transport belt, the vacuum plenum, and the heater are configured to dry the marking material on the printed item while the printed item is on the transport belt. The transport belt is a continuous loop belt having opposed parallel edges. 
     One feature of such apparatuses is that the transport belt comprises a second (or for convenience of discussion “middle”) layer between to a first (or for convenience of discussion “outer”) layer and a third (or for convenience of discussion “inner”) layer. The printed item contacts the outer layer of the transport belt. The top and inner layers are non-perforated entangled fiber (non-woven) materials that are air porous. An adhesive can be included in this structure to bond the top and inner layers to the middle layer. The middle layer can be a solid material that is perforated or a non-preforated woven material. If the middle layer is woven, a sufficient amount of space exists between the woven fibers to allow at least as much air to pass as passes through the upper and lower layers. If the middle layer is solid, the material of the middle layer is not air permeable and air only passes through perforations in the middle layer. 
     Further, the top and inner layers are more flexible than the middle layer. The outer layer can be a different material from the inner layer, and the top and inner layers can have different flexibilities. The outer layer provides a surface that applies a vacuum force to the print media being held on the transport that is planar and that does not have perforations, which avoids image quality defects that can occur because of the holes in perforated vacuum belts. 
     In one example, if the middle layer is woven, the fibers of the middle layer are aligned with each other, but are not aligned with, and are not perpendicular to, the edges of the transport belt. In other words, the fibers can be at right angles (90°) to each other, but are at non-parallel, non-perpendicular angles (e.g., 10°, 30°, 45°, 60°, 80°, etc.) to the edges of the transport belt. More specifically, the fibers of the middle layer can, for example, include a first group of parallel linear fibers and a second group of parallel linear fibers, where the first group is arranged perpendicular (90°) to the second group. Additionally, a polymer coating can be included on the middle layer to prevent the first group of parallel linear fibers from moving relative to the second group. 
     These and other features are described in, or are apparent from, the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary systems and methods are described in detail below, with reference to the attached drawing figures, in which: 
         FIG. 1A  is a conceptual schematic perspective-view diagram illustrating portions of devices herein; 
         FIG. 1B  is a conceptual schematic perspective-view diagram illustrating an expanded view of portions of devices herein shown in  FIG. 1A ; 
         FIG. 1C  is a conceptual schematic perspective-view diagram illustrating portions of devices herein in operation; 
         FIG. 2A  is a conceptual schematic cross-sectional view diagram illustrating a portion of a transport belt herein; 
         FIG. 2B  is a conceptual schematic top view diagram illustrating a portion of the transport belt shown in  FIG. 2A ; 
         FIG. 3A  is a conceptual schematic cross-sectional view diagram illustrating a portion of a transport belt herein; 
         FIG. 3B  is a conceptual schematic top view diagram illustrating a portion of the transport belt shown in  FIG. 3A ; 
         FIG. 3C  is an expanded view of a portion of the conceptual schematic top view diagram of a transport belt herein shown in  FIG. 3B ; 
         FIGS. 4 and 5  are conceptual schematic cross-sectional view diagrams illustrating a portion of a transport belt herein; and 
         FIG. 6  is a conceptual schematic diagram illustrating a portion of a printing device herein. 
     
    
    
     DETAILED DESCRIPTION 
     As mentioned above, when vacuum belts are used as the transport belt through printer dryers, the printed item can have highly visible image quality (IQ) defects in the forms of circles and lines in the process direction that correspond to the belt perforation holes and belt edges. The defects are caused by thermal conductivity and vacuum gradients created within the print media sheet between areas of the sheet that contact the heated silicone belt and areas of the sheet that cover the vacuum holes and/or areas of the sheet that are beyond edges of the belt. 
     For example, the solvents used in High Fusion (HF) and High Definition (HD) liquid inks for inkjet printers can often be affected by belt perforations and belt edges. In one example, the combination of higher drying temperatures used to dry HF ink on clay coated media and lower boiling points for the co-solvents in HF ink (especially compared to HD ink) results in the HF co-solvents evaporating early in the drying process. Temperature gradients within the print media created by non-uniform thermal loading produced by discontinuous contact between the paper and the silicone belts, and print media and air, causes the co-solvents to evaporate at different rates. This concentrates the ink pigments at the locations of the greatest gradient (i.e., at the edges of the perforation holes or belt edges). The ghost image of the belt is more pronounced with certain colors, such as cyan, but can also be visible in magenta. 
     Additionally, to keep belts centered on the rollers the ends of some of the rollers can include a crown (area of increased diameter, e.g., 1 mm-3 mm, which results in an incline on the roller ends of 5° to 10°, relative to the roller center). For example, it is not uncommon for the distal 25% of each roller end to have an incline relative to the roller center. The crowns at the ends of the rollers help the belts return to the center of the roller, so as to track properly on the rollers. However, the crowns at the ends of rollers can cause, folding, creasing, or other deformation of the vacuum belt. 
     In order to address such issues, the systems and methods herein use a multilayer, multi-material vacuum transport belt to transport the printed item through the printer dryer. The “outer” (e.g., top) and “inner” (e.g., bottom) layers of the transport belt are low thermally conductive porous (air permeable) entangled fiber fabric materials laminated onto opposite sides of a “middle” (e.g., center or interior) layer that can be a punched (perforated) or woven stiffer substrate, such as a polyimide film (e.g., 4,4′-oxydiphenylene-pyromellitimide film). Because the air permeable fabrics of the outer and inner layers alone do not possess the dimensional stability to follow the crowns/inclines of the rollers for proper tracking and belt life, the underlying stiffer middle material substrate is used for dimensional stability; however, the permeable inner and outer fabrics maintain a uniform, non-perforated, low thermally conductive flat material against the media face, thereby reducing IQ defects. The materials used for the stiffer substrate allow for air permeability (through perforations or gaps between the woven material) while maintaining dimensional stability, even at elevated temperatures, and the permeable fabrics of the inner and outer layers maintain a uniform (non-perforated) low thermally conductive surface that avoids IQ defects. The air permeable fabric belts may be attached to the stiffer substrate through any number of methods such as, but is not limited to, gluing, melting, laminating, etc. 
     The outer and inner layers of the laminated transport belt can be formed of any air permeable fabric, such as a flame-resistant entangled fiber, where in one example heat resistant aramid fibers can be hydro entangled into a non-woven air permeable fabric material (e.g. felt). In contrast, the stiffer middle layer can be made from stiff fibers such as fiberglass, etc., formed as a woven fabric (e.g., a screen) with a denim like weave. Advantageously, the fibers of the middle layer can be positioned at 45 degrees to the main orthogonal fibers (which is useful to prevent the orthogonal fibers from “parallelograming” when a tube of the fabric is twisted). In other words, while some of the fibers of the middle layer can be at 90° to the belt edges (or parallel to the belt edges) other fibers are woven at non-parallel, non-perpendicular angles (e.g., 10°, 30°, 45°, 60°, 80°, etc.) to the edges of the middle layer to prevent any of the fibers from bunching, folding, overlapping, etc., within the middle layer, especially in areas of the transport belt that transition to the inclined areas of the crowns at the roller ends. Such non-orthogonal weave of the fibers of the middle layer helps prevent folding, creasing, bunching, etc., of the middle layer. Further, such woven fabrics can include a polymer coating to further rigidize the weave. 
     With such a laminated transport belt, belt edge IQ defects are eliminated by the use of the low thermal conductivity air permeable fabric. Further, affixing the air permeable fabric to the more dimensionally stable substrate allows for proper belt tracking and life, and because the stiffer substrate is perforated, it allows for air permeability, allowing such to be appropriate for use as a vacuum transport belt. 
       FIG. 1A  is a conceptual schematic perspective-view diagram illustrating that apparatuses herein include, among other components a print engine  106  (any form of print engine that prints using materials that require drying).  FIG. 1B  is a conceptual schematic perspective-view diagram illustrating an expanded view of the device(s) shown in  FIG. 1A , and  FIG. 1C  is a conceptual schematic perspective-view diagram illustrating such device(s) in operation (e.g., the print engine  106  applying marking material to print media to create a printed item  108 ). 
     As shown in  FIGS. 1A-1C , these apparatuses also include a transport belt  120  positioned to receive the printed item  108  from the print engine  106  and configured to move the printed item  108  away from the print engine  106 , a heater  102  having heating elements  104  positioned adjacent to the transport belt  120  and configured to heat the printed item  108  on the transport belt  120 , a vacuum plenum  110  positioned adjacent to the transport belt  120  and configured to draw air (show using downward arrows) through and away from the transport belt  120 , etc. The transport belt  120 , the vacuum plenum  110 , and the heater  102  are configured to dry the marking material on the printed item while the printed item  108  is on the transport belt  120 . The transport belt  120  is a continuous loop belt having opposed parallel edges. 
     As shown in the expanded view in  FIG. 1B , and shown in cross-section along the mid-line of the transport belt  120  in  FIG. 2A  one feature of such apparatuses is that the transport belt  120  comprises a second (or for convenience of discussion “middle”) layer  124  attached to a first (or for convenience of discussion “outer”) layer  122  and to a third (or for convenience of discussion “inner”) layer  126 . The printed item  108  contacts the outer layer  122  of the transport belt  120 . The outer layer  122  and inner layer  126  are porous non-perforated entangled fiber (non-woven) materials through which air can easily pass. The middle layer  124  can be a woven material or a solid material having perforations (openings)  128 . 
       FIGS. 2A  (in cross-section) and  2 B (in top view) show a perforated solid middle layer  124  having perforations  128 . If the middle layer  124  is solid, the material of the middle layer  124  may not be air permeable and air may only pass through the perforations  128  in the middle layer  124 . As also shown in  FIG. 2A , an adhesive  130  can be included in this structure to bond the upper layer  122  and the inner layer  126  to the middle layer  124 . 
     Further, the inner layer  122  and outer layer  126  are more flexible than the middle layer  124 . The outer layer  122  can be a different material from the inner layer  126   126 , and the outer layer  122  and inner layer  126  can have different flexibilities/compressibilities. The outer layer  122  provides a surface that applies a vacuum force (shown by downward arrows in  FIG. 2A ) to the print media  108  being moved in the direction of the horizontal arrow by the transport belt  120 . Air is drawn through the porous outer layer  122 , the perforations  128  of the middle layer  124 , and the porous inner layer  126  by the vacuum applied by the vacuum plenum  110 . Note that the that surface of the outer layer  122  upon which the sheet of print media  108  rests is planar flat) and does not have perforations, which avoids image quality defects that can occur when a printed sheet of print media directly contacts perforations or belt edges when multiple parallel perforated vacuum belts are used as the transport belt through printer dryers. 
       FIGS. 3A-3C  illustrate embodiments herein that include a woven middle layer  124 , where  FIG. 3A  is a cross-sectional view and  FIG. 3B  is a top view diagram illustrating a portion of the middle layer  124 ; and  FIG. 3C  is an expanded view of a portion  138  of the top view shown in  FIG. 3B . If the middle layer  124  is woven, a sufficient amount of space exists between the woven fibers to allow at least as much air to pass as passes through the upper and lower layers  122 ,  126 . As can be seen in  FIGS. 3A-3B , various fibers  134 ,  136  of the middle layer  124  are aligned with (or are perpendicular to) each other, but are not aligned with, and are not perpendicular to, the parallel edges  140  of the transport belt  120 . In other words, the fibers  134 ,  136  can be at right angles (90°) to each other, but are at non-parallel, non-perpendicular angles (e.g., 10°, 30°, 45°, 60°, 80°, etc.) to the edges  140  of the transport belt  120 . More specifically, the fibers  134 ,  136  of the middle layer  124  can, for example, include a first group of parallel linear fibers  134  and a second group of parallel linear fibers  136 , where the first group  134  is arranged perpendicular (90°) to the second group  136 . Additionally, a polymer coating  132  can be included on the middle layer  124  to prevent the first group of parallel linear fibers  134  from moving relative to the second group  136 . 
       FIG. 4  is conceptual schematic cross-sectional view diagram between the edges  140  of the transport belt  120  herein that illustrates a roller  142  having crowned ends  144  that are inclined relative to the middle of the roller  142 . As can be seen in  FIG. 4 , the flexibility and compressibility of the inner layer  126  accommodates for at least some of the incline of the crowned ends  144  of the roller  142 . This helps reduce the amount of bending forces that are applied to the outer sections of the middle layer  124 , which in turn reduces the likelihood that creases, folds, etc., will occur in the middle layer  124  and the transport belt  120  as a whole. In other words, the compressibility/flexibility of the inner layer  126  buffers at least some of the force exerted by the incline of the crowned ends  144  of the roller  142  to reduce damage to the middle layer  124 . 
       FIG. 5  is conceptual schematic cross-sectional view diagram along the midline of the transport belt  120  herein that illustrates that the inner layer  126  reduces the amount of bending that the middle layer  124  endures as the roller  142  rotates. More specifically, without the inner layer  126  in place the middle layer  124  would contact the roller  142  directly and bend around radius R 1 ; however, with the inner layer  126  in place the middle layer  124  bends less around the larger radius R 2 . Such an increased radius reduces the bending forces seen by the middle layer  124 , which increases the expected useful life of the middle layer  124 , and reduces the chances of folding, creasing, etc. 
     Because of their porous nature, the outer layer  122  and the inner layer  126  are more flexible/compressible than the middle layer  124 . However, the flexibility/compressibility of the outer layer  122  may be different from the inner layer  126  because of the different functions they server in such a structure. For example, the inner layer  126  may be more flexible/compressible than the outer layer  122  to allow the inner layer  126  to greatly reduce the amount of bending of the middle layer  124  from the incline of the crowned ends  144 , and to allow the surface of the outer layer  122  to remain stiff and non-compressed to provide a flat surface upon which the printed sheet of media  108  is securely held. By having a stiffer, less flexible/compressible outer layer  122 , even if strong vacuum forces are experienced from the pressure exerted by the printed sheet of media  108 , the outer layer  122  will still maintain a flat surface. The flexibility of the inner layer  126  is limited somewhat in order to still allow the inner layer  126  to provide an increased radius R 2  around the roller  142 . Therefore, the compressibility of the inner layer  126  is balanced between the need to absorb the incline of the crowned ends  144  and the need to increase the radius R 2 . To achieve such stiffness, flexibility, compressibility differences, the outer layer  122  and the inner layer  126  can be made of different materials, different densities, different fiber patterns, different diameter fibers, etc. 
     Thus, as can be seen in  FIGS. 1A-5 , the outer layer  122  provides a flat, lower temperature surface that is free of perforations that contacts the printed sheet of media  108  so as to avoid image quality defects that can result from temperature differences of conventional perforated vacuum belts within printer dryers. Additionally, the middle layer  124  includes fibers arranged at non-parallel, non-perpendicular angles to avoid creasing, folding, etc. Also, the inner layer  126  has a flexibility/compressibility that is balanced to accommodate at least some of the incline of the crowned ends  144  of the roller  142 , while at the same time allowing the inner layer  126  to provide an increased radius R 2  around the roller  142 , with both operations reducing creases, folds, etc., within the middle layer  124 , thereby extending the useful life of the middle layer  124 . 
       FIG. 6  is a conceptual diagram that illustrates many components of printer structures  154  herein that can comprise, for example, a printer, copier, multi-function machine, multi-function device (MFD), etc. The printing device  154  includes a controller/tangible processor  174  and a communications port (input/output)  164  operatively connected to the tangible processor  174  and to a computerized network external to the printing device  154 . Also, the printing device  154  can include at least one accessory functional component, such as a graphical user interface (GUI) assembly  162 . The user may receive messages, instructions, and menu options from, and enter instructions through, the graphical user interface or control panel  162 . 
     The input/output device  164  is used for communications to and from the printing device  154  and comprises a wired device or wireless device (of any form, whether currently known or developed in the future). The tangible processor  174  controls the various actions of the printing device  154 . A non-transitory, tangible, computer storage medium device  160  (which can be optical, magnetic, capacitor based, etc., and is different from a transitory signal) is readable by the tangible processor  174  and stores instructions that the tangible processor  174  executes to allow the computerized device to perform its various functions, such as those described herein. Thus, as shown in  FIG. 6 , a body housing has one or more functional components that operate on power supplied from an alternating current (AC) source  170  by the power supply  168 . The power supply  168  can comprise a common power conversion unit, power storage element (e.g., a battery, etc), etc. 
     The printing device  154  includes at least one marking device (printing engine(s))  106  that use marking material, and are operatively connected to a specialized image processor  174  (that is different from a general purpose computer because it is specialized for processing image data), a media path  186  positioned to supply continuous media or sheets of media from a sheet supply  180  to the marking device(s)  106 , etc. After receiving various markings from the printing engine(s)  106 , the sheets of media can be dried in the dryer  192  (containing the heater  102 , transport belt  120 , vacuum plenum, etc.) and optionally pass to a finisher  184  which can fold, staple, sort, etc., the various printed sheets. Also, the printing device  154  can include at least one accessory functional component (such as a scanner/document handler  182  (automatic document feeder (ADF)), etc.) that also operate on the power supplied from the external power source  170  (through the power supply  168 ). 
     The one or more printing engines  106  are intended to illustrate any marking device that applies marking material (toner, inks, plastics, organic material, etc.) to continuous media, sheets of media, fixed platforms, etc., in two- or three-dimensional printing processes, whether currently known or developed in the future. The printing engines  106  can include, for example, devices that use inkjet printheads, contact printheads, three-dimensional printers, etc. 
     While some exemplary structures are illustrated in the attached drawings, those ordinarily skilled in the art would understand that the drawings are simplified schematic illustrations and that the claims presented below encompass many more features that are not illustrated (or potentially many less) but that are commonly utilized with such devices and systems. Therefore, Applicants do not intend for the claims presented below to be limited by the attached drawings, but instead the attached drawings are merely provided to illustrate a few ways in which the claimed features can be implemented. 
     The terms printer or printing device as used herein encompasses any apparatus, such as a digital copier, bookmaking machine, facsimile machine, multi-function machine, etc., which performs a print outputting function for any purpose. The details of printers, printing engines, etc., are well-known and are not described in detail herein to keep this disclosure focused on the salient features presented. The systems and methods herein can encompass systems and methods that print in color, monochrome, or handle color or monochrome image data. All foregoing systems and methods are specifically applicable to electrostatographic and/or xerographic machines and/or processes. 
     In addition, terms such as “right”, “left”, “vertical”, “horizontal”, “outer”, “inner”, “upper”, “lower”, “under”, “below”, “underlying”, “over”, “overlying”, “parallel”, “perpendicular”, etc., used herein are understood to be relative locations as they are oriented and illustrated in the drawings (unless otherwise indicated). Terms such as “touching”, “on”, “in direct contact”, “abutting”, “directly adjacent to”, etc., mean that at least one element physically contacts another element (without other elements separating the described elements). Further, the terms automated or automatically mean that once a process is started (by a machine or a user), one or more machines perform the process without further input from any user. In the drawings herein, the same identification numeral identifies the same or similar item. 
     It will be appreciated that the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. 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. Unless specifically defined in a specific claim itself, steps or components of the systems and methods herein cannot be implied or imported from any above example as limitations to any particular order, number, position, size, shape, angle, color, or material.