Patent Publication Number: US-2023158816-A1

Title: Tension adjustments in printers to prevent slipping

Description:
BACKGROUND 
     Print devices can be used to print images or text onto print media. Print devices can come in a variety of different forms and use different types of ink. For example, some print devices may be multi-function devices that can provide different functions include fax, copy, print, and the like. Some print devices may use jetted ink, toner cartridges, and the like. 
     Some print devices may be capable of printing on both sides of a print media. For example, the printer may have a paper path that flips the print media. The print device may then print an image or ink on the opposite side of the print media. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of a side view of an example printing device of the present disclosure; 
         FIG.  2    is a block diagram of a top view of an example print module of the printing device of the present disclosure; 
         FIG.  3    is a block diagram of a top view of an example of driver rollers that can adjust an amount of tension to prevent slipping of the present disclosure; 
         FIG.  4    is a flow chart of an example method for adjusting a tension in a drive roller to prevent slipping of the present disclosure; and 
         FIG.  5    is a flow chart of an example method for printing two sides of a print media with different amounts of tension of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Examples described herein provide a device and method for adjusting an amount of tension of a print media in a side-by-side print device. In some print applications, large continuous webs of print media may be fed to a printing device. To print on both sides of the continuous web of print media, the print media may travel over two different sets of printheads. 
     When an image is printed onto one side (e.g., side A in a side-by-side printer) of the print media and dried, the print media may slightly shrink. As a result, when the print media is flipped and fed to a second side (e.g., side B in the side-by-side printer) in the side-by-side print device, the second side may have a different amount of tension. The bottom side of the print media on side B may have the printed image that was printed when the print media was processed on side A. However, the different amount of tension may cause the bottom side of side B to slip against the idler rollers. The slipping can scuff the printed image on the bottom side of the print media on side B causing print quality issues. 
     The present disclosure prevents slippage on the bottom side of the print media on side B by adjusting the tension in a driver roller that controls side B. In one example, the amount of tension on side B may be increased to increase a contact force of the print media to the idler rollers. The increased contact force may prevent the bottom side of the print media on side B from slipping. As a result, scuffing of the printed image on the bottom side of the print media may be avoided. 
     Increasing the tension on side B may cause the print media to move more slowly in side A. The slower speed may cause some slipping on a bottom side of the print media on side A. However, since there is no ink on the bottom side of the print media on side A, the slipping may not cause print quality issues. 
       FIG.  1    illustrates an example printing device  100  of the present disclosure. In one example, the printing device  100  may include a print module  102 , a dryer module  108 , and a turnbar module  110 . In one example, a feed  112  may provide a continuous web of print media  116  through the printing device  100 . A collector  114  may collect the continuous web of print media  116  after a print job on the continuous web of print media  116  is complete. 
     In one example, the continuous web of print media  116  may be fed to the print module  102 . The continuous web of print media  116  may be print media, such as paper. The continuous web of print media  116  may be a continuous roll of paper. In other words, the paper is not cut sheets that may be placed in a paper tray and individually printed. 
     In one example, the print module  102  may include a single set of print bars  104   1  to  104   n  (hereinafter also referred to collectively as print bars  104 ). The print bars  104  may be located over a plurality of rotating idlers or non-rotating bars  106   1  to  106   m  (hereinafter also referred to collectively as idlers  106 ). 
     In one example, each print bar  104  may include two independently controllable sets of printheads. Each set of printheads may be used to print on one of the sides of the continuous web of print media  116 . 
     A width of the print bars  104  and the idlers  106  may be wide enough to accommodate two separate paths of the continuous web of print media  116  (illustrated in  FIG.  2    and discussed below). For example, if the continuous web of print media  116  has a width of 24 inches, the width of the print bars  104  and the idlers  106  may be at least 48 inches, or slightly larger than 48 inches. 
     In one example, the print bars  104  and the idlers  106  may be arranged along an arched path. The arched path may help to ensure that the continuous web of print media  116  stays flat against the idlers  106 . In one example, the print bars  104  and the idlers  106  may be arranged in flat plane or straight line. However, in such an arrangement a vacuum may be included to suck the continuous web of print media  116  against the idlers  106  or a flat platen. 
     In one example, the print module  102  may include drive rollers  118 . The drive rollers  118  may be located in various locations in the print module  102 . For example, the drive rollers  118  may be located after the feed  112 , towards a top of the printing device  100  over the print module  102 , before the print module  102 , after the print module  102 , and the like. The drive rollers  118  may be located in additional locations that are not shown, e.g., after the dryer module  108 . 
     In one example, the drive rollers  118  may control an amount of tension that is applied to the continuous web of print media  116 . As discussed above, the amount of tension may be based on a speed of rotation of the drive rollers  118 . When the drive rollers are driven at a higher speed than the continuous web of print media  116  is traveling, the mismatch may cause a side of the continuous web of print media  116  in contact with the idler rollers  106  to slip against the idler rollers  106 . If there is ink on the side of the continuous web of print media  116  in contact with the idler rollers  106 , the slipping can cause defects or print quality issues. 
       FIG.  2    illustrates a top view of an example of the print module  102  of the present disclosure.  FIG.  2    illustrates how the continuous web of print media  116  travels in a side-by-side path in the print module  102 . For example, the continuous web of print media  116  may travel along a first side, or left side, from the feed  112  over the drive roller  118  and the idler rollers  106 . A first side of the print bars  104  may print on a first side  120  (also referred to as a front side) of the continuous web of print media  116 . For example, the print bars  104  may print an image, text, graphics, and the like, associated with a print job on the first side  120  of the continuous web of print media  116 . 
     The continuous web of print media  116  may then continue to the dryer module  108 . Referring back to  FIG.  1   , after printing on the first side  120 , the continuous web of print media  116  may be fed to the dryer module  108 . Although a single dryer module  108  is illustrated in  FIG.  1   , it should be noted that any number of dryer modules  108  may be deployed. For example, the printing device  100  may include two or more dryer modules  108 . 
     In one example, the dryer module(s)  108  may provide heat or air to dry the printing material or the printing fluid that is dispensed onto the first side  120  of the continuous web of print media  116 . In one example, the dryer module  108  may include a paper path that returns the continuous web of print media  116  below the print module  102  and back to the turnbar module  110 . 
     In one example, the turnbar module  110  may flip or turn over the continuous web of print media  116 . The turnbar module  110  may include any type of mechanism that may flip the continuous web of print media  116 . In one example, the turnbar module  110  may include a set of diagonal air bars that may flip the continuous web of print media  116  and turn the continuous web of print media  116  180 degrees back towards the print module  102 . 
     In one example, after the turnbar module  110 , a second side  122  of the continuous web of print media  116  may be fed to the print module  102 .  FIG.  2    illustrates how the second side  122  of the continuous web of print media  116  is fed on a right side of the print module  102 . A second set of printheads of the print bars  104  may print an image, text, graphics, and the like, associated with a print job on the second side  122  of the continuous web of print media  116 . 
     The bottom side (e.g., the first side  120 ) of the continuous web of print media  116  moving along the right side, or the second side, of the print module  102 , may have ink dispensed from the first side of the print bars  104 . As noted above, if the bottom side of the continuous web of print media  116  traveling along the right side slips against the idler rollers  106 , the ink may smear or be scuffed causing print quality issues. This may occur when a portion of the continuous web of print media  116  shrinks after passing through the dryer module  108 . 
     For example, the portion of the continuous web of print media  116  traveling along the right side may be shrunk after being dried in the dryer module  108 . As a result, the portion of the continuous web of print media  116  traveling along the right side may move more slowly than the portion of the continuous web of print media  116  traveling along the left side. Since the idler rollers  106  are shared by both the first side and the second side of the print module  102 , the idler rollers  106  may move at the higher speed of the continuous web of print media  116  traveling on the right side. The slower speed associated with the portion of the continuous web of print media  116  on the right side due to shrinking combined with the higher speed of rotation of the idler rollers  106  may cause the bottom side (e.g., the front side  120  on the right side of the print module  102 ) of the continuous web of print media  116  to slip against the idler rollers  106 . 
     In one example, the area between the two drive rollers  118  may be referred to as a tension zone. The speed of the drive rollers  118  may be adjusted in a tension zone to increase an amount tension of the portion of the continuous web of print media  116  travelling on the second side of the print module  102 . In one example, the drive roller  118  that is downstream (e.g., a side exiting the print module  102 ) may be adjusted to adjust an amount of tension on the portion of the continuous web of print media  116  traveling on the second side of the print module  102 . 
     Increasing the amount of tension may cause the portion of the continuous web of print media  116  on the second side of the print module  102  to move faster than the portion of the continuous web of print media  116  on the first side of the print module  102 . Increasing the amount of tension may also generate an amount of contact force between the bottom side of the continuous web of print media  116  traveling on the second side of the print module  102  and a common set of idler rollers  106  shared with the portion of the continuous web of print media  116  traveling on the first side of the print module  102 . 
     Thus, adjusting the amount of tension via the drive roller  118  may prevent slipping. As a result, the print quality issues can be avoided by ensuring that the bottom side of the continuous web of print media  116  traveling on the second side of the print module  102  does not slip against the idler rollers  106 . 
     However, the bottom side of the continuous web of print media  116  traveling on the first side of the print module  102  may be moving more slowly than the speed of the idler rollers  106 . This may cause the bottom side of the continuous web of print media  116  traveling on the first side of the print module  102  to slip against the idler rollers  106 . Since the bottom side of the continuous web of print media  116  traveling on the first side of the print module  102  does not have any ink, the slipping may not cause any print quality issues. 
     As can also be seen in  FIG.  2   , the print module  102  may print on the first or front side  120  and the second or back side  122  of the continuous web of print media  116  simultaneously. Said another way, the print module  102  may provide side-by-side two-sided printing for the continuous web of print media  116 . For example, while the print module  102  is printing on the second side  122  of the continuous web of print media  116 , the print module  102  may also print on the first side  120  of a different portion of the continuous web of print media  116 . 
     After the print module  102  prints on the second side  122  of the continuous web of print media  116 , the second side  122  may be fed through the dryer  108 . The continuous web of print media  116  may then be collected by the collector  114 . An example of the paper path is illustrated in  FIG.  1    and shown by arrows  150 . 
     It should be noted that the printing device  100  has been simplified for ease of explanation. The printing device  100  may include additional components that are not shown in  FIG.  1   . For example, the printing device  100  may have a controller to control operation of the drive rollers  118 , the print bars  104 , a reservoir to store print material that is dispensed by the print bars  104 , input/output devices, and the like. 
       FIG.  3    illustrates a block diagram of a top view of example drive rollers  118  of the present disclosure that can adjust an amount of tension in the continuous web of print media  116  to prevent slipping. It should be noted that  FIG.  3    has been simplified for ease of explanation. For example, the idler rollers  106 , the print bars  104 , and the like are not shown. 
     In one example, the driver rollers  118   1  and  118   2  can be located at opposite ends of a tension zone  318 , as described above. The print device  100  may include tension zones  318  along a paper path. The example of the drive rollers  118   1  and  118   2  illustrated in  FIG.  3    may be applicable for any tension zone  318  along the paper path in the print device  100 . 
     In one example, the drive rollers  118   1  and  118   2  may each include a motor  310  coupled to a first drive roller end  312  of the drive roller  118  and a motor  314  coupled to a second drive roller end  316  of the drive roller  118 . The motor  310  may control a rotational speed of the first drive roller end  312  and the motor  314  may control a rotational speed of the second drive roller end  316 . 
     In one example, the first drive roller end  312  of the drive rollers  118   1  and  118   2  may be associated with the first side  120  of the continuous web of print media  116  and the second drive roller end  316  of the drive rollers  118   1  and  118   2  may be associated with the second side  122  of the continuous web of print media  116 . In other words, the continuous web of print media  116  may travel over the first drive roller end  312  of the drive rollers  118   1  and  118   2  to print on the first side  120  and travel over the second drive roller end  316  of the driver rollers  118   1  and  118   2  to print on the second side  122 . Although the first drive roller end  312  and the second drive roller end  316  share a common axis the first drive roller end  312  and the second drive roller end  316  may be driven independently via the respective motors  310  and  314 . 
     As described above, increasing the rotational speed of the first drive roller end  312  or the second drive roller end  316  may increase an amount of tension that is applied to the portion of the continuous web of print media  116  that travels over the first drive roller end  312  or the second drive roller end  316 . Increasing the amount of tension that is applied may increase the amount of contact force between the portion of the continuous web of print media  116  and the idler rollers  106  to prevent slipping. 
     In one example, a load cell  308  or sensor may be located between the first drive roller end  312  of the drive rollers  118   1  and  118   2  and the second drive roller end  316  of the drive rollers  118   1  and  118   2 . In other words, in a tension zone  318 , two load cells  308  may be deployed for each side. The load cell  308  may be deployed as part of the idler rollers  106  or may be a separate component in the tension zone  318 . 
     The load cell  308  may measure an amount of tension (e.g., measured in pounds per square foot (lbs/ft 2 )) in the continuous web of print media  116  that travels over the load cell  308 . The motors  310  and  314  can be controlled based on the amount of tension measured by the load cell  308 . 
     In one example, the print device  100  may include a controller  302  and a memory  304 . The memory  304  may be a non-transitory computer readable storage medium. The controller  302  may be communicatively coupled to the memory  304 , the load cell  308 , and the motors  310  and  314  of the drive rollers  118   1  and  118   2 . The controller  302  may be a processor or an application specific integrated circuit (ASIC) chip. 
     In one example, the controller  302  may adjust a speed of the first drive roller end  312  and/or the second drive roller end  316  of the drive rollers  118   1  and  118   2  by controlling the motors  310  and  314 . In one example, the controller  302  may control the downstream drive roller (e.g., the drive roller  118   1 ). 
     In one example, the controller  302  may receive a measurement of an amount of tension from the load cell  308 . The measurement of the amount of tension may be compared to a threshold  306  stored in the memory  304 . The threshold  306  may be a user defined threshold for a desired amount of tension, or a set operational speed of the continuous web of print media  116 , over the first drive roller end  312  and/or over the second drive roller end  316 . 
     In one example, the controller  302  may automatically increase the amount of tension over the second drive roller end  316  (e.g., the second side  122 ) to ensure that the bottom side of the second side  122  of the continuous web of print media  116  does not slip against the idler rollers  106 . For example, the user defined threshold  306  may be 20 lbs/ft 2  for both the first drive roller end  312  and the second drive roller end  316 . However, the controller  302  may set the threshold for the second drive roller end  316  to be 20% higher (e.g., 24 lbs/ft 2 ). 
     In one example, controller  302  may compare the measured amount of tension to the threshold  306 . Based on the comparison, the controller  302  may control the motor  310  and/or  314  to adjust a speed of the first drive roller end  312  and/or the second drive roller end  316 . Adjusting the rotational speed of the first drive roller end  312  and/or the second drive roller end  316  may cause the amount of tension to increase or decrease, accordingly. 
     For example, the load cell  308  may measure an amount of tension on the second drive roller end  316 . The controller  302  may compare the amount of tension that is measured to the threshold  306  to determine that the measured amount of tension is below the threshold. In response, the controller  302  may increase the power to the motor  314  to cause the second drive roller end  316  to rotate faster. In one example, the controller  302  may execute a feedback loop until the measured amount of tension is above the threshold  306 . 
     In one example, the controller  302  may compare the amount of tension measured by the load cell  308  on the first drive roller end  312  to the amount of tension measured by the load cell  308  on the second drive roller end  316 . As noted above, the controller  302  may control the motors  310  and  314  such that the amount of tension on the second drive roller end  316  is greater than the amount of tension on the first drive roller end  312  to prevent slipping. If the measured amount of tension is greater on the first drive roller end  312  than the second drive roller end  316 , then the controller  302  may adjust the power to the motors  310  and/or  314  such that the amount of tension on the second drive roller end  316  is greater than the amount of tension on the first drive roller end  312 . For example, the amount of power to the motor  310  may be reduced, the amount of power to the motor  314  may be increased, or both. 
       FIG.  4    illustrates a flow diagram of an example method  400  for adjusting a tension in a drive roller to prevent slipping. In an example, the method  400  may be performed by the printing device  100 . 
     At block  402 , the method  400  begins. At block  404 , the method  400  receives a measurement of an amount of tension in a continuous web of print media traveling through a side-by-side print module that prints on a first side and the second side simultaneously. For example, the amount of tension may be measured by a load cell. The load cell maybe part of the idler rollers that the continuous web of print media travel across in the side-by-side print module. 
     In one example, each side of the side-by-side module may have a respective load cell. In other words, a first side may have a first load cell and a second side may have a second load cell. The first load cell may measure an amount of tension in a first portion of the continuous web of print media travelling through the first side of the side-by-side print module. The second load cell may measure an amount of tension in a second portion of the continuous web of print media travelling through the second side of the side-by-side print module. 
     At block  406 , the method  400  compares the amount of tension that is measured to a threshold. In one example, the amount of tension that is measured may be of the second portion of the continuous web of print media travelling through the second side of the side-by-side print module. The threshold may be a desired amount of tension in the continuous web of print media to prevent slipping against the idler rollers on the second side of the side-by-side print module. 
     In one example, the amount of tension that is measured may be for both the first side and the second side of the side-by-side print module. The amount of tension on the first side and the second side that is measured may both be compared to the threshold. In addition, the controller may compare the amount of tension that is measured on the first side to the amount of tension that is measured on the second side. The controller may perform the comparison to ensure that the amounts of tension that are measured in both the first side and the second side are above the desired threshold and also that the amounts of tension measured on the second side is greater than the amount of tension measured on the second side. 
     As discussed, above, the second drive roller may be set to a higher amount of tension to ensure that the image printed on the first side of the continuous web of print media that is now the bottom side when travelling along the second side of the side-by-side print module does not slip against a common set of idler rollers. The second portion of the continuous web of print media that travels along the second side may shrink after being processed by a dryer module. Thus, without setting the amount of tension on the second driver roller higher than the amount of tension on the first drive roller, the bottom side (e.g., the front side after being flipped) may slip against a common set of idler rollers. 
     At block  408 , the method  400  adjusts an amount of power to a motor of a drive roller to adjust the amount of tension in the continuous web of print media traveling to prevent the continuous web of print media from slipping against an idler roller on the second side based on the comparing. In one example, the drive roller may include a first end and a second end that share a common axis, but can be independently driven by a respective motors, as described above and illustrated in  FIG.  3   . In other words, a first motor may be coupled to a first end of the drive roller to control an amount of tension on the first portion of the continuous web of print media travelling over the first side of the side-by-side print module. A second motor may be coupled to a second end of the drive roller to control an amount of tension on the second portion of the continuous web of print media travelling over the second side of the side-by-side print module. 
     In one example, the first drive roller and the second drive roller may be opposite ends of a single drive roller. For example, the drive roller may comprise a first drive roller end and a second drive roller end that share a common axis, but can be independently driven by a respective motor. An example of the driver roller is illustrated in  FIG.  3    and described above. 
     In one example, the motor that is adjusted may be the second motor on the second end of the drive roller to ensure that the amount of tension on the second side is higher than the amount of tension on the first side. In one example, the motor that is adjusted may be both the first motor and the second motor to ensure the amounts of tension on the first side and the second side are both above the threshold. 
     In one example, the blocks  404 ,  406 , and  408  may be continuously repeated as part of a feedback loop. As a result, the controller may continuously monitor the amounts of tension in the continuous web of print media on both the first side and the second side of the side-by-side print module. The controller may then perform adjustments to the motor of the drive roller based on the amounts of tension that are measured. At block  410 , the method  400  ends. 
       FIG.  5    illustrates a flow diagram of an example method  500  for printing two sides of a print media with different amounts of tension. In an example, the method  500  may be performed by the printing device  100 . 
     At block  502 , the method  500  begins. At block  504 , the method  500  moves a continuous web of print media over a first side of a common set of idler rollers at a first amount of tension that is controlled by a first drive roller to receive an image by a first side of a single set of print bars. For example, a side-by-side printer may have a left side (e.g., the first side) and a right side (e.g., a second side). The continuous web of print media may be fed from a feeder through the first side such that printing fluid or ink is dispensed on the first side of the continuous web of print media. 
     At block  506 , the method  500  dries the image. For example, the first side of the continuous web of print media may be fed through a dryer module to dry the printing fluid. 
     At block  508 , the method  500  flips the continuous web of print media. For example, a turnbar module may flip the continuous web of print media. For example, the first side enters the turnbar module facing up. The turnbar module may flip the continuous web of print media such that the first side is facing down as the continuous web of print media exits the turnbar module. 
     In one example, the turnbar module may also rotate the continuous web of print media 180 degrees. For example, the continuous web of print media may enter the turnbar module in a first direction. The turnbar module may redirect the continuous web of print media in a second direction that is parallel to and directly opposite the first direction after flipping the continuous web of print media. 
     At block  510 , the method  500  moves the continuous web of print media over a second side of the common set of idler rollers at a second amount of tension that is controlled by a second drive roller, wherein the second amount of tension is different than the first amount of tension such that a side of the continuous web of print media with the image maintains a continuous contact against the common set of idler rollers while being moved by the second drive roller. In one example, the second amount of tension may be greater than the first amount of tension such that the first side of the continuous web of media (which may be the bottom side as it travels over the second side of the common set of idler rollers) does not slip against the second side of the common set of idler rollers. 
     In one example, the amount of tension in the first drive roller and the second drive roller may be continuously or periodically measured by a load cell or sensor. A controller may automatically control the amount of tension on the first drive roller and the second driver roller based on the measured amount of tension. In one example, the amount of tension may be adjusted based on a comparison of the measured amount of tension on the first drive roller compared to the measured amount of tension on the second drive roller. For example, the amount of tension on the second drive roller should be higher than the amount of tension on the first drive roller. 
     In one example, the controller may automatically control the amount of tension on the first drive roller and the second drive roller based on a comparison of the measured amounts of tension to a threshold. For example, the amount of tension on the first drive roller and/or second drive roller may be increased or decreased based on the comparison to the threshold. At block  512 , the method  500  ends. 
     It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be 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.