Abstract:
Examples disclosed herein relate to application of a coating fluid. Examples include an apparatus including a first coating applicator to apply a coating fluid to a plurality of first rollers; a first transfer roller in contact with the plurality of first rollers to receive coating fluid; and a media path to apply coating fluid from the first transfer roller to a first side of a media, wherein the plurality of first rollers are shorter than the first transfer roller and are individually movable along its longitudinal axes such that they may positioned to apply a variable width of coating fluid onto the first transfer roller.

Description:
BACKGROUND 
       [0001]    Digital printing presses offer a way to print on a variety of print medium, such as a paper substrate, a foil substrate, and a plastic substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]    The following detailed description references the drawings, wherein: 
           [0003]      FIG. 1  is a partial schematic front perspective view of a printing press according to an example. 
           [0004]      FIG. 2  is a schematic cross-sectional view of the printing press of  FIG. 1  taken along line  2 - 2 ′ according to an example. 
           [0005]      FIG. 3  is a partial schematic side perspective view of the printing press of  FIG. 1  according to an example. 
           [0006]      FIG. 4  is a schematic cross-sectional view of a printing press according to an example. 
           [0007]      FIG. 5  is a partial schematic side perspective view of the printing press of  FIG. 4  according to an example. 
           [0008]      FIG. 6  is a flowchart of an example method for applying coating fluid to a print medium according to an example. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    In the following discussion and in the claims, the term “couple” or “couples” is intended to include suitable indirect and/or direct connections. Thus, if a first component is described as being coupled to a second component that coupling may, for example, be: (1) through a direct electrical or mechanical connection, (2) through an indirect electrical or mechanical connection via other devices and connections, (3) through an optical electrical connection, (4) through a wireless electrical connection, and/or (5) another suitable coupling. The term “approximately” as used herein to modify a value is intended to be determined based on the understanding of one of ordinary skill in the art, and can, for example, mean plus or minus 10% of that value. 
         [0010]    A number of coating fluids may be applied to a print medium to facilitate printing. This process may be referred to as priming. For example, a print medium may be primed before printing an image using printing material, for example, printing fluids (e.g., inks, etc.), printing compounds, etc. Priming can increase the color gamut printable on the print medium, improve fixing of a printed image on the print medium, i.e., durability of the printing material when printed, and/or enable additional degrees of freedom to the ink and printing process design. 
         [0011]    A roller may be used to apply the coating fluid to the print medium in a printing press. The size or width of a print medium may vary. To facilitate printing on medium of varying widths, at least one roller in a media path of the printing press should include coating fluid of a width matched to a printing width of the print medium. In an example, a layer of coating fluid is applied evenly on the print medium via the use of two rollers, a first roller to pick up the coating fluid and transfer it to a second roller to provide the coating fluid to the print medium. However, replacing the first roller or the second roller to provide a coating fluid of varying width is a time and labor consuming process. A roller may be manually replaced with a roller having a contact portion of the determined printing width. In addition, pre-manufacturing the replaceable roller to the determined printing width for multiple different printing mediums and keeping an inventory of rollers with the commonly used print width is costly. 
         [0012]    To address these issues, in the examples described herein, a system that can adjust the width of a coating fluid applied to a roller in a printing press is provided. The system includes a pickup roller which can be moved along a longitudinal axis to provide coating fluid at a desired location and varied width. In some examples, a second pickup roller may also be moved along a longitudinal axis to vary a width of coating fluid applied to the print medium. 
         [0013]    Referring now to the drawings,  FIG. 1  is a partial schematic front perspective view of a printing press  100  according to an example.  FIG. 2  is a schematic cross-sectional view of the printing press  100  of  FIG. 1  taken along line  2 - 2 ′ according to an example.  FIG. 3  is a partial schematic side perspective view of the printing press of  FIG. 1  according to an example. Referring to  FIGS. 1-3 , printing press  100  includes a media path  110  along which a first press roller  112  is rotationally coupled to a second press roller  114  to transfer a coating fluid onto a print medium  190  on media path  110 . In the example of  FIG. 1 , first press roller  112  is to apply a coating fluid to one side of print medium  190 . In some examples, first press roller  112  may deposit a coating fluid having a thickness of approximately 0.1-10 micrometers on print medium  190 . 
         [0014]    A transfer roller  120  is rotationally coupled with first press roller  112  to provide the coating fluid. Transfer roller  120  may receive the coating fluid from a first pickup roller  130  and a second pickup roller  140 . Although depicted with two pickup rollers (first pickup roller  130  and second pickup roller  140 ), the examples are not limited thereto and any number of pickup rollers may be used. 
         [0015]    First pickup roller  130  and second pickup roller  140  may be in a fluid reservoir  150  to pick up the coating fluid from fluid reservoir  150  to provide to first transfer roller  120 . Coating fluid  150  may include any fluid or compound to be disposed on print medium  190  including a primer, a toner, an printing material, a finishing fluid, etc. First pickup roller  130  includes a contact part  133  which is rotationally coupled to transfer roller  120  to provide the coating fluid. Contact part  133  has a longitudinal length less than or equal to the longitudinal length of transfer roller  120  to provide coating fluid to a portion of transfer roller  120 . Contact part  133  may be moved along the longitudinal axis of first pickup roller  130  to provide the coating fluid at a different location on transfer roller  120 . Similarly, second pickup roller  140  includes a contact part  143  rotationally coupled to transfer roller  120  to provide the coating fluid. Contact part  143  has a longitudinal length less than or equal to the longitudinal length of transfer roller  120 . Contact part  143  may be moved along the longitudinal axis of second pickup roller  140  to provide a coating fluid at a different location on transfer roller  120 . In some examples, contact part  133  and contact part  143  may be moved manually or automatically along respective longitudinal axes. In some examples, contact part  133  and contact part  143  may be of the same length or a different length. In an example, contact part  133  and contact part  143  may be positioned to partially or completely align with each other in a longitudinal direction to provide coating fluid of a certain width to transfer roller  120  at a certain location. For example, as shown in  FIG. 3 , contact part  133  and contact part  143  partially overlap to provide coating fluid of a longitudinal length  129  to transfer roller  120 . In such an example, if contact part  133  and/or contact part  143  was moved along its longitudinal axis, i.e., parallel to longitudinal length  129 , the amount of coating fluid to be deposited on transfer roller  120  may be changed. In other words, as the position of contact part  133  and contact part  143  is moved, the longitudinal length  129  of coating fluid provided to first transfer roller  120  is moved or changes in longitudinal length. 
         [0016]    In some examples, a wiper  125  may be coupled to a transfer roller  120  to remove some coating fluid from transfer roller  120 . In such an example, wiper  125  may be used to control the amount of coating fluid provided to first press roller  112 . In some examples, the removed coating fluid may be provided to a fluid reservoir  150  and thereby recycled in printing press  100 . 
         [0017]    In the example of  FIGS. 1-3 , each of first press roller  112  and second press roller  114  rotate about its respective longitudinal axis as print medium  190  moves through printing press  100 . Similarly, each of transfer roller  120 , first pickup roller  130 , and second pickup roller  140  rotate about its respective longitudinal axis when print medium  190  moves along media path  110  through printing press  100 . 
         [0018]    In some examples, printing press  100  may include a controller  105  to determine the width and location of the coating fluid to be applied to transfer roller  120  according to a width of print medium  190 . In such an example, controller  105  may provide instructions for manually adjusting the position of first pickup roller  130  and second pickup roller  140  to a user via a user interface (such as a monitor, a graphical user interface, etc.), a message (e.g., an email message, a SMS message, etc.), or any other mechanism. In other examples, controller  105  may control the automatic movement of contact part  133  and contact part  143  to the determined width and location. For example, contact part  133  and contact part  143  may be automatically moved via pulley. In such an example, in response to receiving an image to be printed on to print medium  190 , controller  105  determines the width and location of coating fluid to be applied to print medium  190  and controls the automatic movement of contact part  133  and contact part  143  to the determined location and to form the determined width. In other examples, contact part  133  and/or contact part  143  may be moved by pushing first pickup roller  130  and second pickup roller  140 , respectively, along its longitudinal axis. 
         [0019]    Referring to  FIG. 3 , the width of coating fluid to be applied to transfer roller  120  may be adjusted according to the relative position of contact part  133  along the longitudinal axis of first pickup roller  130  and contact part  143  along the longitudinal axis of second pickup roller  140 . For example, when aligned with each other, the width of coating fluid applied to transfer roller  120  may be the same length along a longitudinal axis as the longer of contact portion  133  and contact portion  143 . In another example, contact portion  133  and contact portion  143  may be of the same length along its respective longitudinal axis and the width of the coating fluid applied to transfer roller  120  may be the same length as either contact portion  133  or contact portion  134  along its respective longitudinal axis when contact portion  133  and contact portions  143  are aligned. In some examples, first pickup roller  130  and second pickup roller  140  may deposit a coating fluid having a thickness of approximately 1-100 micrometers on transfer roller  120 . 
         [0020]      FIG. 4  is a schematic cross-sectional view of a printing press  200  according to an example.  FIG. 5  is a partial schematic side perspective view of printing press  200  of  FIG. 4  according to an example. Printing press  200  includes a first press roller  212  rotationally coupled to a second press roller  214  to transfer a coating fluid onto a print medium  290 . In the example of  FIGS. 4-5 , first press roller  212  is to apply a coating fluid to one side of print medium  290  and second press roller  214  is to apply coating fluid to the other side of print medium  290 . The coating fluid applied by first press roller  212  and second press roller  214  may be any fluid or compound to be disposed on print medium  290  including a primer, a toner, a printing material, a finishing fluid, etc. In some examples, the coating fluid applied by first press roller  212  and second press roller  214  may be the same coating fluid or different coating fluids. In some examples, first press roller  212  and second press roller  214  may deposit a coating fluid having a thickness of approximately 0.1-10 micrometers on print medium  290 , respectively. 
         [0021]    A first transfer roller  220  is rotationally coupled with first press roller  212  to provide the coating fluid. First transfer roller  220  may receive the coating fluid from a first pickup roller  230  and a second pickup roller  240 . Although depicted with two pickup rollers (first pickup roller  230  and second pickup roller  240 ), the examples are not limited thereto and any number of pickup rollers may be used. In some examples, a first wiper  225  may be coupled to first transfer roller  220  to remove coating fluid from first transfer roller  220 . In such an example, first wiper  225  may be used to control the amount of coating fluid provided to first press roller  212 . In some examples, the removed coating fluid may be provided to a first fluid reservoir  235  and/or a second fluid reservoir  245  and thereby recycled in printing press  200 . First pickup roller  230  may be in first fluid reservoir  235  and second pickup roller  240  may be in second fluid reservoir  245  to pick up the coating fluid to provide to first transfer roller  220 . However, the examples are not limited thereto and first pickup roller  230  and second pickup roller  240  may receive the coating fluid via any type of coating applicator, such as, a spray nozzle, etc. In some examples, the coating fluid in first reservoir  235  and second reservoir  245  may be the same or different coating fluids. In some examples, first pickup roller  230  and second pickup roller  240  may deposit a coating fluid having a thickness of approximately 1-100 micrometers on first transfer roller  220 . 
         [0022]    A second transfer roller  260  is rotationally coupled to second press roller  214  to provide the coating fluid. Second transfer roller  260  may receive the coating fluid from a third pickup roller  270  and a forth pickup roller  280 . Although depicted with two pickup rollers (third pickup roller  270  and forth pickup roller  280 ), the examples are not limited thereto and any number of pickup rollers may be used. In some examples, a second wiper  265  may be coupled to second transfer roller  260  to remove coating fluid from second transfer roller  260 . In such an example, second wiper  265  may be used to control the amount of coating fluid provided to second press roller  214 . In some examples, the removed coating fluid may be provided to a fluid reservoir  250  and thereby recycled in printing press  200 . Third pickup roller  270  and fourth pickup roller  280  may be in third fluid reservoir  250  to pick up the coating fluid to provide to second transfer roller  260 . However, the examples are not limited thereto and third pickup roller  270  and fourth pickup roller  280  may receive the coating fluid via any type of coating applicator, such as, a spray nozzle, etc. In some examples, third pickup roller  270  and forth pickup roller  280  may deposit a coating fluid having a thickness of approximately  1 - 100  micrometers on second transfer roller  260 . 
         [0023]    In the example of  FIGS. 4-5 , each of first press roller  212  and second press roller  214  rotate about its respective longitudinal axis as print medium  290  moves through printing press  200 . Similarly, first transfer roller  220 , second transfer roller  260 , first pickup roller  230 , second pickup roller  240 , third pickup roller  270 , and fourth pickup roller  280  rotate about its respective longitudinal axis when print medium  290  moves through printing press  200 . 
         [0024]    First pickup roller  230  includes a contact part  233  which is rotationally coupled to first transfer roller  220  to provide the coating fluid. Contact part  233  has a longitudinal length less than or equal to the longitudinal length of first transfer roller  220  to provide coating fluid to a portion of first transfer roller  220 . Contact part  233  may be moved along its longitudinal axis to provide a coating fluid at a different location on first transfer roller  220 . Similarly, second pickup roller  240  includes a contact part  243  rotationally coupled to first transfer roller  220  to provide the coating fluid. Contact part  243  has a longitudinal length less than or equal to the longitudinal length of first transfer roller  220 . Contact part  243  may be moved along its longitudinal axis to provide a coating fluid at a different location on first transfer roller  220 . In some examples, each contact part  233  and contact part  243  may be moved manually or automatically along its respective longitudinal axis. In some examples, contact part  233  and contact part  243  may of the same length or a different length. In an example, contact part  233  and contact part  243  may be positioned to partially or completely overlap each other in a longitudinal direction to provide coating fluid of a certain width to first transfer roller  220  at a certain location. For example, as shown in  FIG. 5 , contact part  233  and contact part  243  partially overlap to provide coating fluid of a longitudinal length  229  to first transfer roller  220 . In such an example, if contact part  233  and/or contact part  243  was moved along its longitudinal axis, i.e., parallel to longitudinal length  229 , the amount of coating fluid to be deposited on first transfer roller  220  may be changed. In other words, as the position of contact part  243  and contact part  233  is moved, the longitudinal length  229  of coating fluid provided to first transfer roller  220  is moved or changes in longitudinal length (see for comparison longitudinal length  129  of  FIG. 1 ). 
         [0025]    Third pickup roller  270  includes a contact part  273  which is rotationally coupled to second transfer roller  260  to provide the coating fluid. Contact part  273  has a longitudinal length less than or equal to the longitudinal length of second transfer roller  260  to provide coating fluid to a portion of second transfer roller  260 . Contact part  273  may be moved along its longitudinal axis to provide a coating fluid at a different location on second transfer roller  260 . Similarly, fourth pickup roller  280  includes a contact part  283  rotationally coupled to second transfer roller  260  to provide the coating fluid. Contact part  283  has a longitudinal length less than or equal to the longitudinal length of transfer roller  260 . Contact part  283  may be moved along its longitudinal axis to provide a coating fluid at a different location on second transfer roller  260 . In some examples, each of contact part  273  and contact part  283  may be moved manually or automatically along its respective longitudinal axis. In some examples, contact part  273  and contact part  283  may be of the same length or a different length. In an example, contact part  273  and contact part  283  may be positioned to partially or completely align with each other in a longitudinal direction to provide coating fluid of a certain width to second transfer roller  260  at a certain location. For example, as shown in  FIG. 5 , contact part  273  and contact part  283  partially overlap to provide coating fluid of a longitudinal length  269  to second transfer roller  260 . In such an example, if contact part  273  and/or contact part  283  was moved along its longitudinal axis, i.e., parallel to longitudinal length  269 , the amount of coating fluid to be deposited on second transfer roller  260  may be changed. In other words, as the position of contact part  273  and contact part  283  is moved, the longitudinal length  269  of coating fluid provided to second transfer roller  260  is moved or changes in longitudinal length (see for comparison longitudinal length  129  of  FIG. 1 ). The amount of coating fluid deposited on the print medium may be between 0.1 micrometers-10 micrometers. 
         [0026]    A controller  205  of printing press  200  may determine the width and location of the coating fluid to be applied to first transfer roller  220  and second transfer roller  260  according to a width of a print job (i.e., printing width) on print medium  290 . In such an example, controller  205  may provide instructions for manually adjusting the position of first pickup roller  230 , second pickup roller  240 , third pickup roller  270 , and fourth pickup roller  280  to a user via a user interface (such as a monitor, a graphical user interface, etc.), a message (e.g., email message, SMS message, etc.), or any other mechanism. In other examples, controller  205  may control the automatic movement of contact part  233 , contact part  243 , contact part  273 , and contact part  283  to the determined width and location. For example, contact part  233 , contact part  243 , contact part  273 , and contact part  283  may be automatically moved via a pulley. In such an example, in response to receiving an image to be printed on to print medium  290 , controller  205  determines the width and location of coating fluid to be applied to print medium  290  and controls the automatic movement of contact part  233  and contact part  243  to form longitudinal length  229  and contact part  273  and contact part  283  to form longitudinal length  269 . In other examples, one or more of contact part  233 , contact part  243 , contact part  273 , and contact part  283  may be moved by pushing its respective pick up roller along its longitudinal axis. 
         [0027]      FIG. 6  is a flowchart of an example method  600  for applying coating fluid to a print medium according to an example. Although execution of method  600  is described below with reference to printing press  100  described above, other suitable systems (printing press  200 ) for the execution of method  600  can be utilized. Additionally, implementation of method  600  is not limited to such examples. 
         [0028]    At  602  of method  600 , a controller of printing press  100  may determine a width and a location of a print job according to a width of print medium  190  in media path  110 . In an example, print medium  190  may be at least one of a paper substrate, a plastic substrate, and a metal substrate. 
         [0029]    At  604 , controller  105  of printing press  100  may automatically move first pickup roller  130  and second pickup roller  140  individually along respective longitudinal axes of first pickup roller  130  and second pickup roller  140  to align first pickup roller  130  and second pickup roller  140  with the width and the location of the print job. In other words, contact portion  133  of first pickup roller  130  and contact portion  143  of second pickup roller  140  may be positioned according to the determined width and location of the print job. In the example of  FIG. 6 , the longitudinal width of contact portion  133  and contact portion  143  may be less than or equal to the longitudinal width of the transfer roller  120 . 
         [0030]    At  606 , the coating fluid from a coating application, such as coating reservoir  150 , is applied to a transfer roller  120  via first pickup roller  130  and second pickup roller  140 . In some examples, a second transfer roller (e.g., second transfer roller  260 ) may be rotationally coupled to one or more press rollers to provide a coating fluid to print medium  190 . 
         [0031]    At  608 , the coating fluid is applied to print medium  190  from the transfer roller  120  via first press roller  112 . In an example the coating fluid may be at least one of a primer, a liquid toner, a printing material, a finishing fluid, etc. 
         [0032]    Although the flowchart of  FIG. 6  shows a specific order of performance of certain functionalities, method  600  is not limited to that order. For example, the functionalities shown in succession in the flowchart may be performed in a different order, may be executed concurrently or with partial concurrence, or a combination thereof. In some examples, functionalities described herein in relation to  FIG. 6  may be provided in combination with functionalities described herein in relation to any of  FIGS. 1-5 . 
         [0033]    While certain implementations have been shown and described above, various changes in form and details may be made. For example, some features that have been described in relation to one implementation and/or process can be related to other implementations. In other words, processes, features, components, and/or properties described in relation to one implementation can be useful in other implementations. Furthermore, it should be understood that the systems, apparatuses, and methods described herein can include various combinations and/or sub-combinations of the components and/or features of the different implementations described. Thus, features described with reference to one or more implementations can be combined with other implementations described herein. 
         [0034]    The above discussion is meant to be illustrative of the principles and various examples of the present disclosure. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.