Abstract:
A method for substantially removing “roll-set curl” in a rolled print medium. Roll-set curl, as the name implies, may be defined as the “memory” a print medium has which causes the print medium to tend to return to the shape it had while on the core, once the print medium is unrolled. Additionally, a method for printing on both sides of a print medium in which a roll-set curl has been substantially removed. In one respect, according to a preferred embodiment, a take-up reel is utilized to substantially remove the roll-set curl.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to large format inkjet printers. More particularly, the invention pertains to a method for substantially removing roll-set curl in a print medium to facilitate the printing on both sides of the print medium.  
         BACKGROUND OF THE INVENTION  
         [0002]    Large format ink jet printers are typically utilized to perform double-sided printing. When double-sided printing operations are conducted on cut sheets of print medium, i.e., sheets that have been packaged into various cut sizes, double-sided printing thereon may be effectuated with relative ease. However, when a print medium has been packaged in a roll, it is typically difficult to print onto both sides thereof because of roll-set curl.  
           [0003]    By virtue of the print medium being stored as a roll, as the print medium is unrolled from a core, the print medium typically retains some level of “curliness”. That is, print medium rolled on a core typically suffers from a condition known as “roll-set curl”. Roll-set curl, as the name implies, may be defined as the “memory” a print medium has which causes the print medium to return to the shape it had while on the core, once the print medium is unrolled.  
           [0004]    The roll-set curl condition often makes it relatively difficult to load the print medium to print on the second side of the print medium. In one respect, the roll-set curl may raise the print medium in the print medium path, thus placing it in a position for a carriage of a large format printer to crash into the print medium during a printing operation.  
           [0005]    As discussed hereinabove, one known manner of printing on both sides of a print medium is to use cut sheets. Another conventional manner of printing on both sides of a print medium is to print on one side of a print medium from a roll, cutting the print medium, and then reloading the sheet back into the printer device. However, both of the above-described manners of printing on both sides of a print medium limit the length of an obtainable printed output. That is, conventional techniques of double-sided printing are incapable of producing relatively long plot streams printed on both sides of a print medium.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the principles of the present invention, a method of removing roll-set curl in a print medium rolled on a core utilizing a large format printer equipped with a take up reel (“TUR”) having a core is described. In the method, the TUR is activated and the rolled print medium is loaded into the large format printer. The rolled print medium is advanced through the large format printer until a front edge of the rolled print medium is adjacent to the TUR core. The front edge of rolled print medium is adhered to the core of the TUR. The core of the TUR is rotated in a direction substantially opposite a direction of the rolled print medium on the core to substantially wind the rolled print medium on to the core of the TUR.  
           [0007]    According to another aspect, the present invention pertains to a method of printing on both sides of a print medium rolled on a core utilizing a large format printer equipped with a take up reel (“TUR”) having a first core. According to the method, the TUR is activated and the rolled print medium is loaded into the large format printer. A plot stream is sent to the large format printer and printed onto a first surface of the rolled print medium. The rolled print medium is advanced through the large format printer until a front edge of the rolled print medium is adjacent to the first core of the TUR. The front edge of the rolled print medium is adhered to the first core of the TUR. The first core of the TUR is wound in a direction substantially opposite a direction of the print medium roll to substantially wind the rolled print medium on to the first core of the TUR. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    Features and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the drawings, in which:  
         [0009]    FIGS.  1 A- 1 C together illustrate a flow diagram depicting a manner in which roll-set curl in a rolled print medium may be substantially removed to facilitate two-sided printing on the print medium in accordance with the principles of the present invention;  
         [0010]    [0010]FIG. 2 is a schematic illustration of a manner in which a print medium having one side printed upon is attached to a take up reel in accordance with the principles of the present invention;  
         [0011]    [0011]FIGS. 3A and 3B are schematic illustrations of a manner in which a print medium rolled onto a take up reel is attached to a printer spindle in accordance with the principles of the present invention;  
         [0012]    [0012]FIG. 4 is a schematic illustration showing a manner of rolling a print medium from a printer to a TUR core to prevent a printed side of the print medium from becoming damaged during the print medium rolling operation; and  
         [0013]    [0013]FIG. 5 is a schematic illustration showing a manner of printing onto a second side of a rolled print medium after a print medium has been rolled onto a TUR core. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0014]    For simplicity and illustrative purposes, the principles of the present invention are described by referring mainly to exemplary embodiments thereof, particularly with references to printing plot streams in large format ink jet printers. However, one of ordinary skill in the art would readily recognize that the same principles are equally applicable to any type of print operation, and can be implemented in, any device that may benefit from the principles of the present invention, and that any such variation would be within such modifications that do not depart from the true spirit and scope of the present invention. Thus, although the present invention is described with particular reference to large format ink jet printers and to the printing of plot streams, it will be apparent to one of ordinary skill in the art that the present invention may be practiced with any other suitable printing device and with various other types of printable executable files.  
         [0015]    Although the present invention may be used in any printing environment which incorporates thermal ink jet technology, the presently preferred embodiment of the present invention is used in a large format ink jet printer which is schematically illustrated in FIG. 2. More particularly, the presently preferred embodiment of the present invention is implemented in a Hewlett Packard 5000 large format ink jet printer. Additionally, the preferred embodiment of the present invention is implemented in a printing environment having a take-up reel  14  (“TUR”) that may be attached to a large format ink jet printer  12 .  
         [0016]    As schematically illustrated in FIG. 2, the TUR  14  is generally positioned below an output portion of a large format printer  12  to receive a print medium during printing thereon. In this respect, the TUR  14  typically possesses a first TUR core  212  upon which a print medium is to be rolled as the print medium is printed upon by the large format printer  12 . In general, the first TUR core  212  is typically 36″ in length, however, the present invention is not limited to the use of a 36″ long core. Rather, the present invention may utilize a first TUR core  212  having any reasonably suitable length. The TUR  14  also typically possesses a spindle  214  for winding the first TUR core  212  to thereby enable the print medium to become rolled on the first TUR core as it exits the printer  12 .  
         [0017]    According to the principles of the present invention, as also schematically illustrated in FIG. 2, the printer  12  may receive data (e.g., plot streams) to print from a host device, e.g. computer system  10 . Additionally, the printer  12  typically possesses a display  16  through which a plurality of printer options may be viewed and altered.  
         [0018]    Generally speaking, the present invention pertains to a manner of substantially removing roll-set curl in a print medium. In addition, the present invention pertains to a manner of printing on both sides of a print medium in which roll-set curl has been substantially removed. In one respect, according to a preferred embodiment of the present invention, and as will be better realized from the following disclosure, the TUR  14  is utilized to substantially remove the roll-set curl in a rolled print medium.  
         [0019]    FIGS.  1 A- 1 C, together, illustrate a flow diagram  100  depicting a manner in which roll-set curl in a rolled print medium may be substantially removed to facilitate two-sided printing on the print medium, in accordance with the principles of the present invention. Referring first to FIG. 1A, the TUR  14  is activated at step  102 . The TUR  14  is activated by selecting, in the printer display  16 , a printer icon, which then activates a printer setup options menu possessing the option to activate the TUR.  
         [0020]    Once the TUR  14  has been activated, certain parameters for the printing operation may be set. In this regard, the “Nesting” feature may be deactivated as indicated in step  104 . The nesting feature typically enables images to be printed side-by-side on the print medium rather than one after the other, to avoid wasting print medium. This feature may typically be implemented in those situations where the images have a relatively smaller width than the print medium, making it possible to print more than one image across the width of the print medium. During double sided printing, if the nesting feature is activated, the images printed on one side may not match with the images printed on the second side for a variety of reasons (e.g., mirroring effect, an uneven distribution of the images through the print medium width, etc.). Thus, it is advantageous to disable the nesting feature when printing on both sides of a print medium.  
         [0021]    In a HP 5000 ink jet printer, for example, the nesting feature may be deactivated by selecting the printer icon on the front panel display of the printer, selecting the “Nesting and Queue Management” menu, selecting “Nest”, and choosing the “Off” option.  
         [0022]    An additional parameter to set for the printing operation includes the activation of the extended margins feature as indicated in step  106 . Activation of the extended margins feature typically extends the unprinted margins on the print medium (e.g., from 7 mm to 15 mm lateral and frontal margins). In one respect, the extended margins feature may be activated to avoid lateral head crashes when printing the second side due to potential surface deformations caused by the printing onto the first side, to facilitate the trimming of the lateral margins in case there is relative skew in the loaded print medium, etc. In a HP 5000 ink jet printer, for example, the extended margins feature may be activated by selecting the printer icon on the front panel display  16  of the printer  12 , selecting “extended margins”, and choosing the “On” option.  
         [0023]    Yet another parameter to set for the printing operation includes the deactivation of the color calibration feature as indicated in step  108 . Typically, the color calibration feature operates to improve the color consistency between images, and from one image to another. In this respect, the printer  12  typically calibrates the color by printing a “calibration strip” and scanning the strip with an optical sensor. By virtue of the sensed calibration strip, the printer  12  applies the color correction to subsequently printed images. The color calibration feature is typically performed when a print head is replaced or for each newly introduced print media type that has not previously been calibrated for the current set of print heads. In general, when a print head is changed in the middle of a plot stream, and the color calibration feature is activated, the calibration strip is typically printed, thus modifying the margins between the images and causing a variation in the colors between the printed images, and further causing a mismatch between the samples printed on the first printed side and the second side. In a HP 5000 printer, for example, the color calibration feature may be deactivated by selecting the printer icon on the front panel display of the printer, selecting an “Internal RIP” settings menu, selecting “Color Calibration”, and choosing the “Off” option.  
         [0024]    Another parameter to set for the printing operation includes the deactivation of the “Clean Platen” feature as indicated in step  110 . The clean platen feature is typically activated to avoid the formation of marks underneath the print medium caused by accumulated ink deposits on the platen. In this respect, the clean platen feature generally operates to remove accumulated ink deposits from the platen by utilizing the loaded print medium. More specifically, the printer  12  generally moves a portion of the print medium forwards and backwards over the platen to remove the ink deposits. According to a preferred embodiment, the platen is manually cleaned prior to printing on the first side of the print medium and the clean platen feature is deactivated to avoid ink marks from being placed on the second side of the print medium. In a HP 5000 printer, for example, the clean platen feature may be deactivated by selecting a printer icon on the front panel display of the printer, selecting “utilities/clean platen/automatic clean”, and choosing the “Off” option.  
         [0025]    Although specific reference has been made hereinabove with respect to the setting of certain parameters prior to initiation of the printing operation, it to be understood that the present invention may be practiced without following all of the enumerated steps. In addition, it is also within the scope and spirit of the present invention that the parameters may be implemented in any order.  
         [0026]    Once the above-printing operation parameters have been set, the print medium may be installed onto the printer  12  at step  112 . Referring now to FIG. 2, this step typically includes the positioning of a spindle  202  of the printer  12  into the core  204  of a rolled print medium  206  in such a manner as to enable the print medium  208  to be substantially accurately fed into a printing area of the printer. That is, in a HP 5000 printer, for example, a leading edge of the print medium is visible and inserted into the printer such that a first printing side is positioned to be printed upon. As illustrated in FIG. 1A, the step following the print medium installation step typically includes the sending of plot stream information to the printer  12  from the computer  10  system as indicated in step  114 . However, it is to be understood that the plot stream may be sent to the printer  12  prior to the print medium  208  installation step without departing from the spirit and scope of the present invention. In either event, as the printer  12  prints onto a first surface  210  of the print medium  208 , the print medium is advanced through the printer. When a sufficient length of the print medium has advanced through the printer  12 , i.e., a front edge of the print medium  208  is adjacent to the TUR, the front edge  216  of the print medium is attached to a first TUR core  212  as indicated in step  116 . The front edge  216  of the print medium  208  may be attached to the first TUR core  212  by any known removable fastening means, e.g., adhesive, adhesive tape, mechanical fasteners, etc. Additionally, the front edge  216  of the print medium  208  is attached to a first TUR core  212 , such that the first surface  210  of the print medium is in contact with an outer surface of the first TUR core, as illustrated in FIG. 2.  
         [0027]    According to a preferred embodiment of the present invention, the front edge  216  of the print medium  208  is attached to the first TUR core  212  in such a manner as to substantially prevent the printed image on the first surface  210  from becoming damaged. In this respect, adhesive tape that does not leave any residue is preferred as well as ensuring that the tape is only placed around the edges of the print medium  208  without substantially overlapping the printed image. Additionally, it is preferable to utilize TUR cores that are substantially free of any materials that may be transferred or otherwise damage the printed side of the print medium.  
         [0028]    Referring once again to FIG. 1A, once the front edge of the print medium is attached to the first TUR core  212 , an advance button          located on the TUR  14  is depressed periodically to rotate the first TUR core and thus roll the print medium  208  onto the first TUR core as indicated in step  118 . Referring back to FIG. 2, the first TUR core  212  is positioned over a TUR spindle  214 , which enables the first TUR core to be rotated in either direction. Because the TUR  14  is typically equipped with a sensor to automatically detect when a sufficient length of the print medium  208  has advanced to thus signal the TUR spindle  214  to roll in a direction opposite the direction that the print medium has been installed on the first TUR core  212 , according to a preferred embodiment, a sensor located on the TUR may be blocked to avoid the automatic re-rolling of the print medium in the opposite direction.  
         [0029]    Referring now to FIG. 1B, after the plot stream information has been printed onto the first surface  210  of the print medium  208 , a “Load/Unload” button on the printer front panel (not shown) is depressed twice as indicated in step  120 . In response to the first depression of the “Load/Unload” button, the printer  12  typically operates to cut the print medium  208 . In response to the second depression of the “Load/Unload” button, the printer  12  typically operates to release the rolled print medium  206  and its core  204  from the spindle  202 .  
         [0030]    After the printing operation on the first surface  210  of the print medium  208  is complete, the remaining portion of the print medium may be rolled onto the first TUR core  212 . The unused portion, if any, of the rolled print medium  206  and the core  204  are removed from the printer spindle  202  as indicated in step  122 . Additionally, the first TUR core  212  and the print medium  208  may be removed from the TUR  14  and installed on the printer spindle  202  as indicated in step  124 . In performing step  124 , as illustrated in FIG. 3A, the print medium  208  rolled onto the first TUR core  212  is removed from the TUR spindle  214  (FIG. 3A) and installed on the printer spindle  202  (FIG. 3B), such that the first surface  210  possessing the printed plot stream remains in a position substantially facing the printer spindle.  
         [0031]    Although the description of the present invention above made particular reference to printing on a surface  210  of the print medium  208 , it is to be generally understood that certain of the steps involved for the printing operation may be omitted to substantially remove the roll-set curl in the print medium. It is thus within the principles of the present invention to install the print medium  208  in the manner illustrated in FIG. 2 and roll the print medium onto the first TUR core  212  without printing on a surface of the print medium.  
         [0032]    The print medium  208  and the first TUR core  212  may be installed on the printer spindle  202  as illustrated in FIG. 3B. When the print medium  208  is installed on the printer spindle  202  in this manner, an image printed on the second surface  222  will be in one direction with respect to the image printed on the first surface  210 . However, if it is desired to print the image on the second surface  222  in the other direction with respect to the image printed on the first surface  210 , the plot stream may be sent to the printer in reverse order. According to a preferred embodiment, the print medium  208  may be rolled onto a second TUR core  218 . In this respect, as indicated in step  126 , the second TUR core  218  is installed on the TUR spindle  214  in the manner illustrated in FIG. 4. Additionally, as indicated in step  128 , the print medium is attached to the second TUR core  218  by any known removable fastening means, e.g., adhesive, adhesive tape, mechanical fasteners, etc. As seen in FIG. 4, the print medium  208  is unrolled from the first TUR core  212  and a front edge of the print medium  208  is attached to the second TUR core  218  in a manner similar to that described hereinabove with respect to the first TUR core  212 . That is, the print medium  208  is attached to the second TUR core  218  with the first surface  210  facing the second TUR core. Thus, the print medium  208  is attached to the second TUR core  218  in a manner which enables the print medium to be rolled onto the second TUR core in a direction opposite the first TUR core  212 . As indicated in step  130 , once the print medium  208  is attached to the second TUR core  218 , an advance button          located on the TUR  14  is depressed periodically to rotate the second TUR core  218  and thus roll the print medium  208  onto the second TUR core.  
         [0033]    Referring back to FIG. 4, the printer  12  typically possesses a deflector bar  220  over which print medium  208  typically passes after it has been printed upon. However, because the first surface  210  has an image printed thereon, it has been found to be advantageous to prevent the print medium  208  from passing over the deflector bar  220  by positioning the printed print medium generally behind the deflector bar as illustrated in FIG. 4.  
         [0034]    Once the print medium  208  has been rolled onto the second TUR core  218 , the second TUR core and the print medium are removed from the TUR spindle  214  as indicated in step  132 . As the print medium  208  is rolled onto the second TUR core  218 , a “telescoping” effect may occur causing the print medium to be skewed on the second TUR core. One relatively simple manner in which the “telescoping” effect may be removed involves the lifting of the print medium  208  and the second TUR core  218  off the ground a relatively short distance (e.g., 2 inches) and relatively gently dropping the second TUR core and the print medium on the ground.  
         [0035]    Referring now to FIG. 1C, the second TUR core  218  and the print medium  208  are installed on the printer spindle  202  as indicated in step  134 . In following this step, the second TUR core  218  and the print medium  208  may require a 180° rotation across the vertical axis to assign the print medium in proper position for printing onto the second side of the print medium (e.g., in a HP 5000 printer). Once the print medium  208  is installed on the printer spindle  202 , as illustrated in FIG. 5, step  136  typically includes the sending of plot stream information to the printer  12  from the computer system  10 . However, it is to be understood that the plot stream may be sent to the printer  12  prior to the installation of the print medium  208  without departing from the spirit and scope of the present invention. In either event, as the printer  12  prints onto the second surface  222  of the print medium  208 , as in step  138 , the print medium is advanced through the printer and exits out of the printer. When a sufficient length of the print medium  208  has advanced through the printer  12 , i.e., the print medium is adjacent to a third TUR core  224 , the print medium is attached to the third TUR core  224  at step  140 . The print medium  208  may be attached to the third TUR core  224  by any known removable fastening means, e.g., adhesive, adhesive tape, mechanical fasteners, etc. Additionally, the print medium  208  is attached to the third TUR core  224  such that the first surface  210  of the print medium is in contact with an outer surface of the third TUR core as illustrated in FIG. 5. As the plot stream information is printed onto the second surface  222  of the print medium  208 , the print medium exiting the printer  12  is rolled onto the third TUR core  224  as indicated in step  142 .  
         [0036]    As described hereinabove, the present invention pertains to a method of removing roll-set curl in a rolled print medium to facilitate double-sided printing of relatively long plot streams.  
         [0037]    What has been described and illustrated herein are preferred embodiments of the invention along with some of their variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims—and their equivalents—in which all terms are meant current their broadest reasonable sense unless otherwise indicated.