Abstract:
An apparatus for facilitating handling of sheets in a sheet-fed printing press comprising a matte that is mountable on a cylinder. The matte has at least one inflatable pocket for cushioning sheets of printable material as they are passed between two cylinders of the press. At least one valve communicates with the inflatable pocket and controls the quantity of fluid in the inflatable pocket. A number of inflatable pockets can be utilized to provide increased control over various sheet sizes. Further control may be obtained by including a number of valves to independently operate each of the inflatable pockets. Ease of installation and removal is accomplished by incorporated mounting holes along the long axis of the matte. Alternatively, the matte may be arranged on the cylinder by adhesively bonding (tape or glue) the matte to the surface of the cylinder or by arranging the matte on the cylinder with Velcro fasteners. A number of mattes may be combined to form a compound matte resulting in greater resolution and precision. Methods for making as well as using the apparatus are also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates generally to a system and method of reducing marking or smearing of printed sheets on sheet-fed printing presses, and, more particularly, to a matte for use on a cylinder in a sheet-fed printing press. 
     2. Description of Related Art 
     Marking and smearing of freshly printed sheets during high speed printing operations on sheet-fed printers have historically been troublesome, costly and time consuming problems. Various methods have been employed to effectuate the handling and transfer of freshly printed sheets between printing stations, or between a printing station and a press delivery, without marking or smearing of the printed sheets. These methods have utilized various types of skeleton wheels, cylinders and other mechanical devices. 
     Skeleton wheels typically attempt to minimize contact with the printed sheet by using projections or serrations. However, some inherent problems associated with the use of skeleton wheels include sliding of the printed sheet over the projections or serrations or damaging of the sheet itself through indenting or dimpling. By contrast, other methods do not attempt to minimize contact with the printed sheet but instead either provide a coating material applied directly to a transfer cylinder or skeleton wheel which acts as an ink repellant or by mounting a covering on the transfer cylinder or skeleton wheel which is itself coated with an ink repellant and which additionally performs a cushioning function. 
     The drawbacks and shortcomings of these approaches have resulted in increased labor costs and the attendant loss of efficiency (attributed to: complex installations; increased setup time to accommodate varying sheet sizes, and increased time for frequent washing of the transfer cylinders), increased make-ready time, high maintenance requirements and increased waste. Some of these inherent drawbacks and shortcomings of these various methods are more fully discussed in U.S. Pat. Nos. 5,842,412 and 4,402,267. 
     In a sheet-fed press, the leading edge of a sheet of printable material is guided via a gripper whereas the trailing edge is typically free. During operation, the gripper pulls the leading edge of the sheet of printable material through the space found generally between two cylinders of the press. This space, or gap, between two adjacent cylinders of the press is often referred to as the “nip.” High speed operation of a press using such a gripper arrangement results in additional drawbacks or shortcomings generally known by those of ordinary skill in the art of sheet-fed printing. Some of these additional drawbacks or shortcomings include, but are not necessarily limited to, smearing or marking of wet images, dot distortion, print length difference between one print station and another during transfer within a print output device and “slap-out” of the trailing edge of a printed sheet of material. 
     Slap-out occurs due to a combination of factors, including but not necessarily limited to the trailing edge of the sheet being free, the tendency of the printed sheet to return to a flat or straight position, and the path of the trailing edge through the nip being defined as something other than tangentially between the two cylinders; i.e., since the surface on which the sheet travels is cylindrical and since the opposing surface is also cylindrical, there exists a path between the two surfaces located at the nip which would be simultaneously tangential to both opposing cylindrical surfaces. Were the sheet to travel along this tangential path, there would be no associated problem of slap-out no matter how fast the press was operated. However, since the actual path of the printed sheet is never along this tangential path, the problem of slap-out becomes prevalent and increases with press speed and the degree to which the printed sheet must alter its course from the tangential path. 
     Therefore, a need exists for an improved device and method to reduce smearing or marking of wet images, dot distortion, print length difference between one print station and another during transfer within a print output device and “slap-out” of the trailing edge of a printed sheet of material. 
     SUMMARY OF THE INVENTION 
     In one embodiment, an apparatus for facilitating handling of sheets in a sheet-fed printing press includes a matte that is mountable on the transfer cylinder. The matte has at least one inflatable pocket for cushioning sheets of printable material as they are passed through the nip. At least one valve arranged to be in fluid communication with the inflatable pocket may be provided for controlling a quantity of fluid in the inflatable pocket. The cushioning provided by use of such an apparatus reduces smearing or marking of wet images, dot distortion, print length difference between one print station and another during transfer within a print output device and “slap-out” of the trailing edge of a printed sheet of material. 
     In another embodiment, a plurality of inflatable pockets located at locations spaced along the long axis of the matte may be included to provide for increased control over various sheet sizes. Additional control over various sheet sizes may be obtained by including a plurality of valves to independently operate each of the inflatable pockets. Ease of installation and removal is accomplished by incorporated mounting holes along the long axis of the matte. Alternatively, the matte may be arranged on the cylinder by adhesively bonding (tape or glue) the matte to the surface of the cylinder or by arranging the matte on the cylinder with VELCRO hook and loop fasteners. 
     In another embodiment of the present invention, the transfer cylinder is adapted to receive at least one inflatable tube directly onto the outer surface of the transfer cylinder. At least one valve arranged to be in fluid communication with the inflatable tube may be provided for controlling the quantity of fluid in the inflatable tubes. 
     A plurality of inflatable tubes may be arranged onto the outer surface of the transfer cylinder and at a plurality of locations along the transfer cylinder&#39;s length in order to provide increased control over various sheet sizes. Additional control over various sheet sizes may be obtained by including a plurality of valves for independently controlling the quantity of fluid in each of the plurality of inflatable tubes. 
     In yet another embodiment, a plurality of grooves are provided in the outer surface of the transfer cylinder extending along the circumference of the transfer cylinder. A pliable membrane is then arranged onto the transfer cylinder and is sealingly attached to the outer surface of the transfer cylinder so as to form sealed cavities. In order to reduce the sealing area, the pliable membrane may be sealingly attached at the outer periphery of each groove, or anywhere from the outer periphery of one groove to a point on the outer surface of the transfer cylinder that is halfway to the next adjacent groove. The pliable membrane may also be sealed to the entire exposed surface of the transfer cylinder as well. Sealing may be effectuated using either an adhesive (tape or glue) or a mechanical sealing means such as an O-ring. 
     At least one valve arranged to be in fluid communication with the sealed cavities may be provided for controlling the quantity of fluid in the sealed cavities. A plurality of grooves spaced at locations preferably along the long axis of the transfer cylinder resulting in a plurality of sealed cavities may be provided for increased control over various sheet sizes. Additional control over various sheet sizes may be obtained by including a plurality of valves for independently controlling the quantity of fluid in each of the plurality of sealed cavities. 
     In another embodiment of the invention, a compound matte including at least two mattes is mountable on a cylinder of a sheet-fed printing press. The compound matte includes a first matte and a second matte, each matte having at least one inflatable pocket for cushioning sheets of printed material as they are passed through the first and second cylinders. The second matte is arranged on the first matte and the second matte has openings adapted to allow the at least one inflatable pocket of the first matte to pass when it is inflated. 
     The invention also includes the method of fabricating a matte having at least one inflatable pocket for facilitating handling of sheets in a sheet-fed printing press. The method includes the steps of selecting an appropriate material and forming the matte with at least one inflatable pocket using means suitable for the chosen material. 
     Additionally, the invention also includes the method of facilitating handling of sheets in a sheet-fed printing press which includes arranging a matte with at least one inflatable pocket onto the transfer cylinder, selecting a printed sheet size to be fed through the press, actuating at least one valve for controlling the quantity of fluid in the inflatable pocket in accordance with the sheet size selected and operating the sheet-fed printing press so as to cause the printed sheet to be passed through the nip. 
     BRIEF DESCRIPTION OF DRAWINGS 
     The accompanying drawings illustrate certain embodiments of the invention. 
     FIG. 1 a  is a cross-sectional view depicting a general overview of a printing system with a matte arranged on a transfer cylinder in accordance with one embodiment; 
     FIG. 1 b  is an enlarged view of a “nip,” or gap, between the transfer cylinder and the impression cylinder; 
     FIG. 2 is a plan view of the matte of FIG. 1 b  illustrating the general configuration; 
     FIG. 3 a  is a plan view of the system of FIG. 1 b  in operation depicting two different sheet sizes; 
     FIG. 3 b  is a detailed view of that portion of FIG. 3 a  indicated by the dashed circle depicting operation of the system with one sheet size and the corresponding pockets inflated; 
     FIG. 3 c  is similar to FIG. 3 b  except that a different sheet size is depicted with corresponding pockets inflated; 
     FIG. 4 a  is a cross-sectional view of an alternative embodiment wherein inflatable tubes are arranged directly onto the transfer cylinder via grooves in the outer surface of the transfer cylinder; 
     FIG. 4 b  is a cross-sectional view of another alternative embodiment wherein the inflatable tubes are adapted to be arranged directly onto the existing outer surface of the transfer cylinder without the need for grooves; 
     FIG. 5 a  is a front elevation view of a further alternative embodiment which has a pliable membrane mounted on a transfer cylinder, the transfer cylinder having grooves in its outer surface so that the pliable membrane and the grooves form sealed cavities; 
     FIG. 5 b  is a plan view of the pliable membrane depicted in FIG. 5 a.    
     FIG. 6 is a cross-sectional view taken along the line  6 — 6  in FIG. 5 a  illustrating the pliable membrane arranged on the transfer cylinder; 
     FIG. 7 is a cross-sectional view taken along the line  7 — 7  in FIG. 5 a  illustrating both activated and deactivated sealed cavities; 
     FIG. 8 is a cross-sectional view taken along the line  7 — 7  in FIG. 5 a  illustrating an alternative sealing means for the embodiment of FIG. 5 a;    
     FIG. 9 is a plan view depicting a compound matte which uses more than one matte arranged one atop the other; 
     FIGS.  10  and FIG. 10B are a plan view depicting a general overview of a printing system utilizing the compound matte of FIG. 9; and 
     FIG. 11 is a plan view of the compound matte of FIG. 10 with the inflatable pockets of each individual matte corresponding to the non-print areas of the printed sheet of material inflated. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Certain preferred embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 a  generally depicts an overall sheet-fed printing press system with a matte  130  arranged on transfer cylinder  100 . Sheet-fed printing presses generally include a transfer cylinder  100  and an impression cylinder  105 . The sheet-fed printing press is modified by mounting a matte  130  onto the outer surface of the transfer cylinder  100  wherein the matte  130  includes at least one inflatable pocket  125 . This inflatable pocket  125  may take various shapes and sizes; size being limited only by the dimensions of the matte  130  itself. Possible shapes include but are not limited to a circle, square, rectangle, rectangle with rounded edges, ellipse, etc. 
     It is noted that although the matte  130  is shown arranged on a transfer cylinder  100 , and although the majority of the discussion here refers to the transfer cylinder  100 , the matte  130  can generally be arranged on any cylinder in a sheet-fed printing press which could derive the benefits and advantages offered by the matte  130 . Additionally, although the matte  130  is shown with inflatable pockets  125 , it is to be understood that solid tubes, or various other solid shapes, constructed of a suitable elastic or pliable material can be used to cushion sheets of printed material as they are passed between cylinders of the sheet-fed printing press. Further, solid shapes may be used in addition to, or in conjunction with, inflatable pockets  125 . 
     At least one valve  135  may be included in the overall system which is adapted to be in fluid communication with both a fluid medium source  140 , e.g., air, on its input side  136  and the inflatable pockets  125  on its output side  137 . The valve  135  can be sealed between the layers  210  of the benz matte  130  itself or it can be mounted to the transfer cylinder  100 , as can the fluid medium source  140 , in such a manner as to allow for normal operation of the transfer cylinder  100 . The valve can either be manually actuated to inflate/deflate the inflatable pockets or it can be automatically actuated via a computerized control system  145  to control the quantity of fluid medium  140  inside the inflatable pockets as desired. The pockets  125  may be selectively inflated or deflated according to many possible factors including, but necessarily limited to the size of the sheet being printed, the printing press being utilized, the locations of the printed and non-printed areas on the printable material being passed through the printing press, etc. Alternatively, a valve for each inflatable pocket can be used in order to independently control each inflatable pocket. It is emphasized that the inflatable pockets may be controlled through the use of any suitable fluid medium, air being one such fluid medium. 
     FIG. 2 provides a more detailed view of the benz matte  130 . The benz matte  130  generally includes at least two or more layers  210  horizontally disposed to one another and sealingly engaged at various locations along preferably the long axis of the matte; the long axis of the matte coincides with the long axis of the transfer cylinder. The material for the matte can be Polyvinylchloride (PVC), either clear or frosty, or any other material suitable for carrying out the invention; e.g. rubbers, plastics, polyesters, non-permeable fabrics, etc. The layers  210  of the matte are sealed in such a manner so as to form pockets  125 , or unsealed areas, between the layers which are oriented along the short axis; the short axis of the matte coincides with the short axis of the transfer cylinder. At least one inflatable pocket  125  is formed between the layers  210  of the benz matte  130 . However, incorporation of a plurality of pockets  125 , as shown in FIG. 2, will allow a single matte to be used for multiple sheet sizes as opposed to having a matte for each corresponding sheet size. 
     The transfer cylinder  100 , as seen in FIG. 1 a , may include mounting studs  115  spaced along its long axis and a gripper bar  110  which extends along its long axis. The matte  130 , as shown in FIG. 2, may include mounting holes  200  located along both of its long axis edges. The mounting holes  200  on the matte  130  may be arranged to receive the mounting studs  115  of the transfer cylinder  100 . The mounting studs  115 , therefore, can be used to quickly and easily mount the benz matte  130  by using the mounting holes  200  provided along its edges. Such an arrangement provides for a simple, cost effective and low maintenance installation. Alternatively, the matte  130  may be mounted onto the transfer cylinder through adhesively bonding the matte  130  to the surface of the transfer cylinder  100  or by securing the matte  130  to the cylinder by using VELCRO hook and loop fasteners (not shown). 
     FIGS. 3 a ,  3   b , and  3   c  show multiple inflatable pockets  125  arranged so that various sizes of sheets  120 ,  121  can be utilized. The locations of the pockets  125  could correspond to the numerous standard sizes of sheet material (e.g., letter, legal, A4, etc.) as well as customized sheet sizes utilized in sheet-fed printing presses. Alternatively, the pockets  125  may be located at incremental positions along the long axis of the matte  130 ; when the matte is mounted on the transfer cylinder, the matte&#39;s short axis would correspond to the circumference of the transfer cylinder. 
     The appropriate pockets  125  would either be inflated or deflated depending upon the size of the sheet material  120 ,  121  being passed through the printing press. For example, in FIG. 3 b  it is shown that the four central pockets  125  are inflated and all the remaining pockets are deflated. This spacing of inflated pockets coincides with the size of the sheet  120  being passed through the nip  150 . In other words, the pockets  125  coincide with the size of the sheet  120  thereby cushioning and supporting the entire sheet as it passes through the nip  150 . This cushioning prevents the end of the sheet from “slapping out” when the press is run at high speeds. 
     Similarly, FIG. 3 c  illustrates a different size sheet  121  being passed through the nip  150 . Accordingly, the six central inflatable pockets  125  are inflated. Again, the sheet  121  is cushioned and slapping-out at high press speeds is reduced or eliminated. The number and spacing of inflatable pockets  125  found on the matte  130  can be varied according to the needs of the user as determined by the range of sheet sizes or other characteristics of the sheets, such as weight. It is important to note that the thickness of the matte  130  and the amount of inflation of the inflatable pockets may vary depending upon the particular application and the particular printing press being used (nip size will vary depending upon the particular printing press. 
     FIG. 4 a  illustrates an alternative embodiment in which grooves  400  are placed in the outer surface of the transfer cylinder  100 . Individual inflatable tubes  410  are then installed into the grooves  400  in the outer surface of the transfer cylinder  100 . The individual tubes  410  may constructed in a manner similar to the matte  130  described above. Operation of the transfer cylinder  100  having the individual tubes  410  installed directly into the grooves  400  in the outer surface of the transfer cylinder  100  is essentially the same as operation of the transfer cylinder  100  using the matte  130 , described above. The number and spacing of grooves  400  and individual inflatable tubes  410  can be varied according to the needs of the user as determined by the range of sheet sizes or other characteristics of the sheets, such as weight. 
     FIG. 4 b  illustrates another alternative embodiment where the inflatable tubes  420  are arranged onto the surface of the transfer cylinder  100  either by adhesively bonding (tape or glue) them to the surface or through use of an appropriate mechanical fastening device, such as fasteners, VELCRO hook and loop fasteners, hooks, etc. 
     Referring to FIGS. 5 a ,  5   b ,  6  and  7 , another embodiment is illustrated wherein the matte  130  of FIG. 2 is omitted. Similar to the embodiment found in FIG. 4 a , grooves  520  having at least a first edge  530  and a second edge  531  are provided in the outer surface of the transfer cylinder  100 . However, instead of employing individual inflatable tubes  410 , a pliable membrane  500  is arranged on the outer surface of the transfer cylinder  100  by mounting the edges of the pliable membrane  500  to mounting studs  115  on the transfer cylinder  100  through use of the mounting holes  510 . The pliable membrane  500  is then sealed to the outer surface of the transfer cylinder  100  in a manner which results in the grooves  520  and the pliable membrane  500  forming sealed cavities  610 . 
     A single valve  135 , or one valve  135  for each groove  520 , can be accommodated within the groove  520  and placed in fluid communication with a fluid medium source  140  to control fluid flow into and out of the sealed cavities  610 . The sealed cavities  610  can then be inflated  710  or deflated  711  with a fluid medium  140  such that the portion of the pliable membrane  500  which is located above the groove  520  in the transfer cylinder  100 , i.e., the portion forming the sealed cavity  610 , is deflected in a radially outward direction (indicated by the dashed lines). It should be noted that the portion of the pliable membrane  500  which is located above the groove  520  could also be mechanically actuated via movable segments of the outer surface of the transfer cylinder  100 ; i.e., a mechanical gearing arrangement could be employed so as to actuate the movable segments and cause a deflection of the pliable membrane in a radially outward direction. 
     Various means for sealing the pliable membrane  500  to the outer surface of the transfer cylinder  100  may be employed. For example, the outer periphery  530 ,  531  of each groove  520  may be sealingly attached to the pliable membrane  500  so that a sealed cavity  610  is thus formed. FIG. 5 a  illustrates this outer periphery sealing arrangement by the shaded area  540  around each groove  520 . It should be noted that sealing may be accomplished through either use of an adhesive (tape or glue) or through use of mechanical means, such as the O-ring  800  depicted in FIG.  8 . Also, the location of the sealed area  540  is not limited by that area depicted in FIG. 5 a  nor is the shape of the sealed area necessarily limited to that of the groove  520 . On the contrary, the location of the sealed area  540  may be at any point ranging from the edges  530 ,  531  of the groove to a point half the distance to the next adjacent groove  520 . Alternatively, the entire pliable membrane  500  may be sealingly attached to the outer surface of the transfer cylinder  100 . 
     A method of fabricating the matte  130  may use any means suitable for sealing the particular material chosen to comprise the layers  210  of the matte  130 . The sealing means would seal the layers at a plurality of locations spaced preferably along the long axis of the matte  130  to form inflatable pockets  125 . For example a radio frequency (RF) sealing method may be employed for materials which respond to such a method or a simple hot press. Additionally, use of adhesive (tape or glue) or chemical grafting may be utilized in fabricating the matte  130 . It should also be noted that the pockets formed using the sealing method may be formed such that they are presently, and will remain, in the inflated state. 
     In addition, while it is preferable to orient the pockets, tubes and grooves along the long axis of the cylinder  130 , the inflatable pockets  125 , inflatable tubes  420  and grooves  400  may be oriented perpendicular to the orientation depicted (not shown). Therefore, the inflatable pockets  125 , inflatable tubes  420  and grooves  400  may also be oriented such that they extend along the length of the cylinder  100  and are spaced at various positions along the circumference of the cylinder  100 . 
     FIG. 9 illustrates an alternative embodiment in which more than one matte  130  is utilized, resulting in a compound matte  930  which would be arranged on a cylinder of the sheet-fed printing press. The compound matte  930  illustrated in FIG. 9 generally includes two mattes  931 ,  932 , each capable of being independently operated or controlled. The two mattes  931 ,  932  are arranged one atop the other in a coplanar manner. The lower matte  932  may be configured as in the matte  130  shown in FIG.  2 . The upper matte  931  may also be generally configured as in the matte  130  shown in FIG. 2 with the exception that openings are provided in the matte  931  which pass through the layers comprising the individual matte  931 . These openings are positioned in the surface of the matte  931  and correspond generally to the shape and location of the inflatable pockets included in the lower matte  932 . 
     Additionally, although the compound matte  930  is shown with inflatable pockets  125 ,  925 , it is to be understood that solid tubes, or various other solid shapes, constructed of a suitable elastic or pliable material can be used to cushion sheets of printed material as they are passed between cylinders of the sheet-fed printing press. Further, solid shapes may be used in addition to, or in conjunction with, inflatable pockets  125 ,  925 , and on the same or different individual mattes  931 ,  932 . For example, individual matte  931  may contain only solid shapes and individual matte  932  may contain only inflatable pockets, or vice versa. Also, individual mattes  931 ,  932  may each simultaneously contain both solid shapes and inflatable pockets. 
     FIGS. 10 and 10B are a general overview of a system  1000  employing the compound matte  930  shown in FIG.  9 . The system  1000  can be used with a printed sheet of material  1010  in order to more precisely transfer the non-print image areas  1050  of the printed sheet of material  1010  to the compound matte  930 ; i.e., to inflate the appropriate inflatable pockets  1020 ,  1030  corresponding to the non-print areas  1050  of the printed sheet of material  1010 . This is generally accomplished through use of the computerized control system  145  and a suitable imaging/plotting software package. 
     An image to be printed, which can consist of text, pictures, drawings, etc. or any combination thereof, can generally be stored in a computerized control system  145  as an electronic file in a format that is compatible with the imaging/plotting software selected; e.g., TIFF, JPEG, BMP, etc. The imaging/plotting software is used to determine the locations of the printed  1040 ,  1041  and non-printed areas  1050  of the image, as shown in FIG.  10 B. The computerized control system  145  then uses this print/non-print data to determine which inflatable pockets  1020 ,  1030  of the compound matte  930  must be inflated; i.e., to inflate those inflatable pockets  1020 ,  1030  corresponding to the non-print areas of the printed sheet of material  1010 . Therefore, as can be seen in FIG. 11, depending on the print/non-print areas, the printed sheet of material  1010  will be cushioned in the appropriate locations as it is passed between two cylinders or as it is transferred from one print station to another. Such an implementation not only reduces slap-out, but also reduces smearing of wet images, dot distortion and print length difference between one print station and another during transfer within a print output device. 
     It should be clear that the compound matte  930  shown in FIGS. 9-11 can be configured for varying degrees of resolution; i.e., an appropriate number, size and shape of inflatable pockets as well as an appropriate number of individual mattes  931 ,  932  comprising the compound matte  930  can be provided depending on the resolution and precision required for a particular application/printing press. 
     Furthermore, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired that the present invention be limited to the exact construction and operation illustrated and described herein, and accordingly, all suitable modifications and equivalents which may be resorted to are intended to fall within the scope of the claims.