Patent Publication Number: US-2016231667-A1

Title: Transfer of ink layers

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. application Ser. No. 14/362,872, filed Jun. 4, 2014, which is a national stage application under 35 U.S.C. §371 of PCT/EP2011/073611, filed Dec. 21, 2011, which are both hereby incorporated by reference in their entirety 
    
    
     BACKGROUND 
     Image forming apparatuses may include ink applicator units, a charging unit, a discharging unit, a photoconductive member, and an intermediate transfer member having an image transfer blanket. During a print cycle, the image forming apparatus may include charging the photoconductive member, selectively discharging a portion of the photoconductive member to form a latent image thereon, developing an ink layer on the photoconductive member, and transferring the developed ink layer from the photoconductive member to the image transfer blanket in a form of a print separation. During a subsequent print cycle, the process may be repeated resulting in another print separation being transferred from the photoconductive member to the image transfer blanket. After the print cycles are completed resulting in the respective print separations being transferred to the image transfer blanket to form a respective ink image thereon, the ink image is transferred from the image transfer blanket to a media. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Non-limiting examples of the present disclosure are described in the following description, read with reference to the figures attached hereto and do not limit the scope of the claims. In the figures, identical and similar structures, elements or parts thereof that appear in more than one figure are generally labeled with the same or similar references in the figures in which they appear. Dimensions of components and features illustrated in the figures are chosen primarily for convenience and clarity of presentation and are not necessarily to scale. Referring to the attached figures: 
         FIG. 1  is a block diagram of an image forming apparatus according to an example. 
         FIG. 2  is a schematic view illustrating an image forming apparatus such as a liquid electrophotography printing system according to an example. 
         FIG. 3  is a perspective view illustrating a photoconductive member having a latent image formed thereon of the image forming apparatus of  FIG. 2  according to an example. 
         FIGS. 4A-4C  are side views illustrating the application and transfer of ink layers within the image forming apparatus of  FIG. 2  according to examples. 
         FIG. 5  is a flowchart illustrating a method of operating an image forming apparatus according to an example. 
         FIG. 6  is a flowchart illustrating an image forming method according to an example. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is depicted by way of illustration specific examples in which the present disclosure may be practiced. It is to be understood that other examples may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. 
     Image forming apparatuses may include ink applicator units such as developer units, a charging unit, a discharging unit, a photoconductive member, and an intermediate transfer member having an image transfer blanket. During a print cycle, the image forming apparatus may charge the photoconductive member, selectively discharge a portion of the photoconductive member to form a latent image thereon, develop an ink layer on the photoconductive member, and transfer the developed ink layer from the photoconductive member to the image transfer blanket in a form of a print separation. During a subsequent print cycle, the process may be repeated resulting in another print separation being transferred from the photoconductive member to the image transfer blanket. After the respective print cycles are completed that result in the respective print separations being transferred to the image transfer blanket to form a respective ink image thereon, the resultant ink image is transferred from the image transfer blanket to a media. The use of an independent print cycle to transfer each ink layer from the photoconductive member to the image transfer blanket may be time consuming and increase wear on the ink transfer blanket. Accordingly, the productivity of the image forming apparatus and the lifespan of the image transfer blanket may decrease. 
     In examples, an image forming apparatus may include, among other things, a plurality of ink applicator units disposed across from a photoconductive member and spaced apart from each other in a rotational direction of the photoconductive member. The ink applicator units may sequentially apply a plurality of ink layers, respectively, toward the latent image to form an ink image. Each one of the ink layers may be in contact with another one of the ink layers. The image forming apparatus may also include an intermediate transfer member having an image transfer blanket to receive the ink image including the plurality of ink layers from the photoconductive member. Thus, the formation of the ink image on the photoconductive member by multiple ink layers and the transfer of the ink image to the image transfer blanket may be accomplished in a single print cycle. The use of a single print cycle to sequentially apply each of ink layers to the photoconductive member and to transfer the group of respective ink layers in the form of an ink image to the image transfer blanket may reduce printing time and decrease wear on the ink transfer blanket. Accordingly, the productivity of the image forming apparatus and the lifespan of the image transfer blanket may increase. 
       FIG. 1  is a block diagram of an image forming apparatus. according to an example. Referring to  FIG. 1 , in examples, an image forming apparatus  100  may include a photoconductive member  10 , a charging unit  12 , a discharging unit  14 , a plurality of ink applicator units  16 , and an intermediate transfer member  18  having an image transfer blanket  18   a . The photoconductive member  10  may move in a rotational direction d r  ( FIG. 2 ). The charging unit  12  may charge the photoconductive member  10 . For example, the charging unit  12  may be a scorotron, charge roller, or the like, to form a uniform electrical charge on a surface of the photoconductive member  10 . The discharging unit  14  may discharge a portion of the photoconductive member  10  to form a latent image thereon. For example, the discharging unit  14  may be a laser, or the like. The discharging unit  14  may form the respective latent image on the photoconductive member  10  based on received image data. 
     The plurality of ink applicator units  16  may be disposed across from the photoconductive member  10  and spaced apart from each other in the rotational direction d r . The ink applicator units  16  may be inkjet printheads, developer units, binary ink developer units, or the like. The ink applicator units  16  may sequentially apply a plurality of ink layers, respectively, toward the latent image to form an ink image. Each one of the ink layers may be in contact with another one of the ink layers. For example, a first ink layer may be applied on top of the latent image formed on the photoconductive member  10 . A second ink layer may be applied on top of the first ink layer. In some examples, additional ink layers may be applied toward the latent image by being applied to the latent image or to a previously-applied ink layer. 
     The ink layer applied by the ink applicator units  16  may be in the form of ink. The ink, for example, may include primer to form a primer layer, colored ink to form a colored-ink layer, and ink overcoat to form an ink overcoating layer. The colored ink, for example, may include at least one of cyan, magenta, yellow, white, black, or the like. For example, the colored ink may be a liquid toner such as Electroink, trademarked by Hewlett-Packard Company, including color pigments. In some examples, the ink may include charge directors having an electrical charge. Accordingly, the electrically-charged ink may be selectively applied toward the discharged portion of the photoconductive member  10  forming the latent image based on a sufficient difference of electrical potential there between. The intermediate transfer member  18  may include an image transfer blanket  18   a  to receive the ink image including the plurality of ink layers from the photoconductive member  10 . The intermediate transfer member  18  may rotate in cooperation with the photoconductive member  10  to receive the ink image from the photoconductive member  10 . 
       FIG. 2  is a schematic view illustrating an image forming apparatus such as a liquid electrophotography printing (LEP) system according to an example.  FIG. 3  is a perspective view illustrating a photoconductive member having a latent image formed thereon of the image forming apparatus of  FIG. 2  according to an example.  FIGS. 4A-4C  are side views illustrating the application and transfer of ink layers within the image forming apparatus of  FIG. 2  according to examples. Referring to  FIG. 2 , the image forming apparatus  200  may include an input unit  29   a , an output unit  29   b , and an image forming unit  29   c . The image forming unit  29   c  may receive a media S from an input unit  29   a  and output the media S to an output unit  29   b . The media S may be transported in a media transport direction d s . The image forming unit  29   c  may include a photoconductive member  10 , a charging unit  12 , a discharging unit  14 , a plurality of ink applicator units  16 , and an intermediate transfer member (ITM)  18  including an image transfer blanket  18   a  as previously disclosed with respect to the image forming apparatus  100  of  FIG. 1 . In some examples, the image forming unit  29   c  may also include an impression member  27 . 
     Referring to  FIGS. 2-4C , in some examples, the charging unit  12  may provide a uniform electrical charge on the photoconductive member  10 . The discharging unit  14  may selectively discharge portions of the photoconductive member  10  to form a latent image  40  thereon. That is, the discharging unit  14  may decrease the electrical potential of the discharged portion of the photoconductive member  10  relative to other portions thereof. In some examples, the image forming apparatus  200  may include only a single discharging unit  14  to form a latent image  40  on the photoconductive member  10 . The ink applicator units  16  may sequentially apply ink layers  41   a ,  41   b , and  41   c  (collectively  41 ), respectively, toward the latent image  40  on the photoconductive member  10  to form an ink image  45 . For example, the ink layers  41  may be formed of ink having an electrical charge that is attracted toward the discharged portion of the photoconductive member  10 . In some examples, the plurality of ink layers  16  may include a dual ink layer structure. That is, a first ink applicator unit  16   a  may apply a first ink layer  41   a  on the latent image  40 . The first ink layer  41   a , for example, may be a primer layer. For example, a primer layer may increase the adhesiveness of subsequent ink layers such as colored-ink layers to adhere to a surface. Alternatively, the first ink layer  41   a  may be a colored-ink layer having a color such as black, or the like. A second ink applicator unit  16   b , disposed downstream from the first ink applicator unit  16   a  in the rotational direction d r , may apply a second ink layer  41  b toward the latent image  40  and on top of the first ink layer  41   a . The second ink layer  41   b , for example, may be a colored-ink layer having a color. In some examples, the colored-ink layer of the second ink layer  41   b  may be the same color of the colored-ink layer of the first ink layer  41   a . Alternatively, the second ink layer  41   a  may be an ink coating layer. Thus, the overall thickness of the ink image  45  may be increased by adding onto each other multiple colored ink layers, for example, having the same color. Such an increased thickness may be used, for example, in raised print applications, embossing applications, or the like. 
     In some examples, the plurality of ink layers  16  may include more than two ink layers  16   a  and  16   b . For example, a third ink applicator unit  16   c , disposed downstream from the second ink applicator unit  16   b  in the rotational direction d r , may apply a third ink layer  41   c  toward the latent image  40  and on top of the second ink layer  41   b . The third ink layer  41   c , for example, may be an ink overcoating layer. The ink overcoating layer may provide a protective coating to the ink image  45  and/or enhance the appearance of the ink image  45 . The ink overcoating layer may include a gloss coating layer, a matte coating layer, or the like. Alternatively, in some examples, the third ink layer  41   c  may be a colored-ink layer having the same color as the second colored-ink layer  41   b . In some examples, the image forming apparatus  200  may include additional ink applicator units to apply colored-ink layers corresponding to a variety of colors. 
     Referring to  FIGS. 3-4C , the respective ink layers  41   a ,  41   b , and  41   c  may be sequentially applied toward the latent image  40  to form the ink image  45  on the photoconductive member  10  prior to the transfer of the ink image  45  from the photoconductive member  10  to the image transfer blanket  18   a  of the ITM  18 . For example, the discharged portion of the photoconductive member  10  may continue to attract additional ink layers  41   b  and  41   c  even after receiving at least one previous ink layer  41  a during the same print cycle. A print cycle, for example, may include the charging of the photoconductive member  10 , a discharging of a portion of the photoconductive member  10  to form a latent image  40  thereon, applying at least one ink layer  41   a  on the photoconductive member  40  corresponding to the latent image  40  to form an ink image  45 , and transferring the ink image  45  to the image transfer blanket  18   a  from the photoconductive member  10 . For example, the respective ink layers  41   a ,  41   b , and  41   c  from the ink applicator units  16  may be applied toward the latent image  40  on the photoconductive member  10  to form the respective ink image  45  during a single rotation of the photoconductive member  10 . 
     Subsequently, the ink image  45  including multiple ink layers  41   a ,  41   b , and  41   c  may be transferred to an image transfer blanket  18   a  of an ITM  18 . That is, the multiple ink layers  41   a ,  41   b , and  41   c  previously and sequentially applied as respective individual ink layers to form the ink image  45  on the photoconductive member  10  are transferred simultaneously as a group to the image transfer blanket  18   a  in the form of the ink image  45 . The photoconductive member  10  may sequentially receive the individual ink layers  41   a ,  41   b , and  41   c  and transfer the multiple ink layers  41   a ,  41   b , and  41   c  there from to the image transfer blanket  18   a  as a group in the form of the ink image  45  during a single print cycle. Subsequently, the ITM  18  may transfer the ink image  45  from the image transfer blanket  18   a  to a media S. In some examples, the ITM  18  may heat the ink image  45  and transfer it to the media S. During the transfer of the ink image  45  from the ITM  18  to the media S, the media S may be pinched between the ITM  18  and an impression member  27 . Once the ink image has been transferred to the media S, the media S can be transported to the output unit  14   b.    
       FIG. 5  is a flowchart illustrating a method of operating an image forming apparatus according to an example. Referring to  FIG. 5 , in block S 510 , a photoconductive member is charged by a charging unit. In block S 520 , a portion of the photoconductive member is discharged by a discharging unit to form a latent image thereon. In block S 530 , a plurality of ink layers is sequentially applied from a plurality of ink applicator units, respectively, toward the latent image to form an ink image such that each one of the ink layers is in contact with another one of the ink layers. The plurality of ink layers may include a dual ink layer structure. For example, a first ink layer may be applied from a first ink applicator unit toward the latent image, and a second ink layer may be applied from a second ink applicator unit toward the latent image and on top of the first ink layer. In some examples, the plurality of ink layers may include more than dual ink layer structure. For example, the plurality of ink layers may include a triple ink layer structure. That is, a third ink layer may be applied from a third ink applicator unit toward the latent image and on top of the second ink layer. Each one of the plurality of ink layers may include charge directors. In some examples, the first ink layer may include one of a primer layer and a colored-ink layer, and the second ink layer may include one of a colored-ink layer and an ink coating layer. In some examples, the third ink layer may include one of a colored-ink layer and an ink coating layer. For example, the ink coating layer may include a gloss coating layer, a matte coating layer, or the like. In block S 540 , the ink image formed by the plurality of ink layers is transferred from the photoconductive member to an image transfer blanket. The method may also include transferring the ink image from the image transfer blanket to a media. 
       FIG. 6  is a flowchart illustrating an image forming method according to an example. Referring to  FIG. 6 , in block S 610 , a photoconductive member is moved in a rotational direction. In block S 620 , a latent image is formed on a portion of a photoconductive member. For example, the portion of the photoconductive member may be discharged by a discharging unit to form the latent image thereon. In block S 630 , a first ink layer is applied from a first ink applicator unit to the latent image formed on the photoconductive member. In block S 640 , a second ink layer is applied from a second ink applicator unit disposed downstream from the first ink applicator unit in the rotational direction on top of the first ink layer. The first ink layer and the second ink layer may form an ink image corresponding to the latent image. In some examples, a third ink layer may be applied from a third ink applicator unit disposed downstream from the second ink applicator unit in the rotational direction on top of the second ink layer. Accordingly, the first ink layer, the second ink layer, and the third ink layer may form the ink image corresponding to the latent image. In block S 650 , the ink image is transferred from the photoconductive member to an image transfer blanket. In some examples, the image forming method may also include charging a photoconductive member by a charging unit and transferring the ink image from the image transfer blanket to a media. 
     It is to be understood that the flowcharts of  FIGS. 5 and 6  illustrate an architecture, functionality, and operation of an example of the present disclosure. If embodied in software, each block may represent a module, segment, or portion of code that includes one or more executable instructions to implement the specified logical function(s). If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). Although the flowcharts of  FIGS. 5 and 6  illustrate a specific order of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order illustrated. Also, two or more blocks illustrated in succession in  FIGS. 5 and 6  may be executed concurrently or with partial concurrence. All such variations are within the scope of the present disclosure. 
     The present disclosure has been described using non-limiting detailed descriptions of examples thereof and is not intended to limit the scope of the present disclosure. It should be understood that features and/or operations described with respect to one example may be used with other examples and that not all examples of the present disclosure have all of the features and/or operations illustrated in a particular figure or described with respect to one of the examples. Variations of examples described will occur to persons of the art. Furthermore, the terms “comprise,” “include,” “have” and their conjugates, shall mean, when used in the present disclosure and/or claims, “including but not necessarily limited to.” 
     It is noted that some of the above described examples may include structure, acts or details of structures and acts that may not be essential to the present disclosure and are intended to be exemplary. Structure and acts described herein are replaceable by equivalents, which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the present disclosure is limited only by the elements and limitations as used in the claims.