Abstract:
The present invention relates to a reverse offset printing method, and more particularly, to a reverse offset printing method in a partial off type capable of accurately transferring a pattern to a cliche to achieve more precise minute printing by separately performing removal for each shear region of a functional ink even though the pattern is minute.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0034394 filed in the Korean Intellectual Property Office on Apr. 3, 2012, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a reverse offset printing method, and more particularly to a reverse offset printing method in a partial off type capable of accurately transferring a pattern to a cliche to achieve more precise minute printing by separately performing removal for each shear region of a functional ink even though the pattern is minute. 
         [0004]    (b) Description of the Related Art 
         [0005]    In general, a cliche (C, see  FIG. 1 ) performs patterning while coming into contact with a blanket B coated with a functional ink and offs (removes) an unnecessary pattern other than a desired shape. 
         [0006]    Hereinafter, a reverse offset electronic printing apparatus  10  will be described as an example, as illustrated in  FIG. 1 . 
         [0007]    The reverse offset electronic printing apparatus  10  includes a blanket B coated with a functional ink I and a cliche C coming into contact with the blanket B to remove an unnecessary pattern. 
         [0008]    That is, as illustrated in  FIG. 1 , the blanket B coated with the functional ink I is first prepared. 
         [0009]    The functional ink I may be coated on the blanket B through widely known methods such as spin coating, slit coating and the like. 
         [0010]    The above-mentioned blanket B coated with the functional ink I is brought into contact with the cliche C including a groove portion CV. 
         [0011]    In this case, the functional ink coming into contact with the groove portion CV remains on the blanket B, and the functional ink coming into contact with a contact surface CA of the cliche C is transferred to the cliche C. 
         [0012]    That is, a part desired to be patterned remains on the blanket B and is transferred to a substrate which is not illustrated in  FIG. 1 , and then printing is performed. 
         [0013]    Meanwhile, in a recently spotlighted electronic printing field, a width of the pattern is equal to or smaller than scores of um in many cases. 
         [0014]    Accordingly, as illustrated in  FIG. 2 , a width L of the groove portion CV of the cliche C is also equal to or smaller than scores of um. 
         [0015]    However, as described above, as the width of the pattern becomes more minute, a size of the pattern remaining on the blanket B becomes very small in comparison with a size of the functional ink transferred to the cliche C from the blanket B. 
         [0016]    In this case, the functional ink which should remain on the blanket B and then be finally transferred to the substrate does not remain on the blanket B and is transferred to the cliche C sometimes. 
         [0017]    The above case may be generated by a phenomenon in which since adhesive force between the blanket B and the functional ink is weaker than shear force of the function ink as illustrated in  FIG. 3 , a connection portion II (hereinafter, referred to as a shear region) between the functional ink which should remain on the blanket B and the functional ink transferred to the cliche C cannot be cut when the blanket B and the cliche C are separated from each other. 
         [0018]    In this case, the functional ink which should remain on the blanket B is taken to the cliche C, and thus accurate printing is not possible. 
         [0019]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0020]    The present invention has been made in an effort to provide a reverse offset printing method in a partial off type capable of accurately transferring a pattern to a cliche to achieve more precise minute printing by separately performing removal for each shear region of a functional ink even though the pattern is minute. 
         [0021]    An exemplary embodiment of the present invention provides a reverse offset printing method including: providing a blanket having one surface coated with a functional ink including a pattern region and shear regions surrounding the pattern region; bringing a first cliche having one surface on which a first contact portion coming into contact with the functional ink including a part of the shear regions is formed into contact with the blanket; separating the blanket from the first cliche to remove the functional ink coming into contact with the first contact portion from the blanket; bringing a second cliche having one surface on which a second contact portion coming into contact with the functional ink including the other part of the shear regions is formed into contact with the blanket; and separating the blanket from the second cliche to remove the functional ink coming into contact with the second contact portion from the blanket. 
         [0022]    In the reverse offset printing method according to the present invention, the pattern region may include a plurality of square cross section shapes spaced apart from each other and arranged in a grid pattern, the first cliche may include a plurality of first contact portions formed in a horizontal direction of the grid pattern and first groove portions engraved between the first contact portions, and the second cliche may include a plurality of second contact portions formed in a vertical direction of the grid pattern and second groove portions engraved between the second contact portions. 
         [0023]    In the reverse offset printing method according to the present invention, a width of the groove portion of the first cliche may be equal to a vertical width of a square. 
         [0024]    In the reverse offset printing method according to the present invention, a width of the groove portion of the second cliche may be equal to a horizontal width of a square. 
         [0025]    In the reverse offset printing method according to the present invention, the pattern region may be formed by a region where the first groove portion and the second groove portion overlap each other. 
         [0026]    In the reverse offset printing method according to the present invention, the functional ink remaining on the blanket after the blanket may be separated from the second cliche corresponds to the pattern region. 
         [0027]    In this case, the reverse offset printing method may include, after the separating of the blanket from the second cliche, transferring the pattern region to a substrate. 
         [0028]    According to the exemplary embodiments of the present invention, it is possible to perform accurate patterning even though a pattern desired to be printed is minute. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIGS. 1 to 2  are conceptual diagrams describing a general reverse offset printing method; 
           [0030]      FIG. 3  is a conceptual diagram describing a problem in the related art; 
           [0031]      FIGS. 4 to 5  are conceptual diagrams describing an exemplary embodiment of the present invention; 
           [0032]      FIGS. 6 to 8  are conceptual diagrams describing another exemplary embodiment of the present invention; and 
           [0033]      FIGS. 9 to 11  are conceptual diagrams describing yet another exemplary embodiment of the present invention. 
       
    
    
     DESCRIPTION OF SYMBOLS  
       [0034]    C: Cliche CV: Contact portion 
         [0035]    S: Substrate B: Blanket 
       DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0036]    Before describing various exemplary embodiments of the present invention in detail, it can be seen that applications thereof are not limited to details of configurations and arrangements of constituent elements which are described in the following detailed description or illustrated in the drawings. 
         [0037]    The present invention may be realized and carried out by other embodiments, and may be performed in various methods. 
         [0038]    Further, it can be seen that expressions and wordings used herein regarding such terms as directions (for example, “front”, “back”, “up”, “down”, “top”, “bottom”, “left”, “right”, and “lateral”) of devices or elements are used only to simplify the description of the present invention and do not represent or mean that the related devices or element needs to have specific directions simply. 
         [0039]    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to the description, the terms and wordings used in the specification and the claims should not be construed to be limited to general and lexical meanings and should be construed as meanings and concepts corresponding with the technical spirit of the present invention based on a principle that the inventor can suitably define the concepts of the terms to describe his or her invention in the best way. 
         [0040]    Thus, the exemplary embodiments described in the specification and the configurations illustrated in the drawings are simply the most preferable embodiments of the present invention and are not representative of all the technical spirits of the present invention, and thus it should be understood that various equivalents and modified examples which can replace them are present at the time when the present invention is filed. 
         [0041]    Hereinafter, the present invention will be described in detail through the accompanying drawings and the exemplary embodiments. 
         [0042]    The present invention relates to a reverse offset printing method, and particularly includes transferring a functional ink to a cliche C from a blanket B separately for each shear region of the functional ink I divided into the functional ink on the cliche C and the functional ink on the blanket B. 
         [0043]    In the related art, there is a method of cutting the shear region (II of  FIG. 3 ) of the functional ink desired to be finally transferred to the substrate at a single stroke, as described above. 
         [0044]    In this case, when the width of the pattern remaining on the blanket B is minute, the shear region is not cut and thus the pattern which should remain on the blanket B is taken to the cliche C. 
         [0045]    The present invention has been made to resolve the above mentioned problems, and according to the present invention, shear regions of the functional ink are not separated at a single stroke, but divisibly separated for each shear region, so that a pattern desired to be finally transferred to a substrate correctly remains on the blanket B unlike the related art even though a width of the pattern remaining on the blanket B is minute, and thus precise minute printing can be achieved. 
       EXAMPLE 1 
       [0046]    Hereinafter, a more detailed description will be made with reference to  FIGS. 4 to 5 . 
         [0047]    First, the blanket B having one surface coated with the functional ink I including shear regions Ia and Ib surrounding a pattern region  13  and a pattern region  13 , is provided. 
         [0048]    The cliche C according to the exemplary embodiment of the present invention includes a plurality of cliches so that respective shear regions are divisibly separated. 
         [0049]    The cliche C includes a first cliche C 1  having one surface on which a contact portion CV 1  coming into contact with the functional ink I including one part of the shear regions is formed to remove the functional ink I on one side of the shear regions of the functional ink I, and a second cliche C 2  having one surface on which a contact portion CV 2  coming into contact with the functional ink I including the other part of the shear regions is formed to remove the functional ink I on the other side of the shear regions. 
         [0050]    That is, as illustrated in  FIG. 4 , the first cliche C 1  is used to first remove the part corresponding to the left shear region Ia among the shear regions of the functional ink I. 
         [0051]    To this end, the first cliche C 1  is brought into contact with the blanket B in order to bring the contact portion CV 1  of the first cliche C 1  into contact with the functional ink existing on the left shear region Ia of the functional ink of the blanket B. In this case, a right end of the contact portion CV 1  may correspond to the left shear region Ia. 
         [0052]    The functional ink I coming into contact with the first contact portion CV 1  is removed from the blanket B by separating the first cliche C 1  from the blanket B. 
         [0053]    After the functional ink of the left shear region Ia is removed by the first cliche C 1 , the right shear region Ib is removed from the second cliche C 2 . 
         [0054]    To this end, as illustrated in  FIG. 5 , the second cliche C 2  is brought into contact with the blanket B in order to bring the contact portion CV 1  of the second cliche C 2  into contact with the functional ink existing on the right shear region Ib of the function ink of the blanket B. In this case, a left end of the contact portion CV 2  may correspond to the right shear region Ib. 
         [0055]    The functional ink I coming into contact with the second contact portion CV 2  is removed from the blanket B by separating the second cliche C 2  from the blanket B. 
         [0056]    By the second cliche C 2 , only the functional ink corresponding to a pattern region I 3  (a part marked with a bold line in  FIGS. 4 and 5 ) desired to be finally transferred to the substrate remains on the blanket B. 
       EXAMPLE 2 
       [0057]    Meanwhile, when the pattern region I 3  desired to be finally printed is formed in a shape in which a plurality of square cross section shapes spaced apart from each other are formed on the substrate S in a grid pattern as illustrated in  FIG. 6 , the printing is performed as follows. 
         [0058]    That is, a first cliche C 3 , as illustrated in  FIG. 7 , may include a plurality of contact portions CV 3  formed in a horizontal direction of the grid pattern to remove the shear region of the functional ink corresponding to the horizontal direction of the grid pattern and a groove portion CC engraved between the contact portions CV 3 . 
         [0059]    In this case, unnecessary functional ink is removed by bring the contact portion CV 3  into contact with the blanket B, and the functional ink of the blanket B coming into contact with the groove portion CC remains on the blanket B. 
         [0060]    That is, an unnecessary part ZONE V corresponding to the horizontal direction of the grid pattern illustrated in  FIG. 6  is first removed by the first cliche C 3 . 
         [0061]    In this case, the first removal of the part ZONE V corresponding to the horizontal direction means first removal of regions Ie and Ic corresponding to the horizontal direction among the shear regions having the grid pattern. 
         [0062]    In other words, parts corresponding to the horizontal direction of the grid pattern may include four regions ZONE V 1 , ZONE V 2 , ZONE V 3 , and ZONE V 4  as illustrated in  FIG. 6 . To this end, four contact portions CV 3  are formed on the first cliche C 3  in the horizontal direction in order to remove the regions ZONE V 1 , ZONE V 2 , ZONE V 3 , and ZONE V 4  as illustrated in  FIG. 7 . 
         [0063]    By the first cliche C 3 , only the shear regions in the horizontal direction of the grid pattern are first removed, and accordingly only the functional ink in the horizontal direction remains on a lower surface of the blanket B as illustrated in  FIG. 8 . 
         [0064]    Particularly, as illustrated in  FIG. 8 , it can be identified that the functional ink remaining on the lower surface of the blanket B is first removed from two shear regions Id and If. 
         [0065]    After only the shear regions in the horizontal direction of the grid pattern are first removed using the first cliche C 3 , shear regions Ic and Id (see  FIG. 6 ) in a vertical direction of the grid pattern are finally removed using a second cliche C 4  illustrated in  FIG. 8 . 
         [0066]    To this end, the second cliche C 4  includes a plurality of contact portions CV 4  formed in the vertical direction of the grid pattern in order to remove the shear regions Ic and Id (see  FIG. 6 ) of the functional ink corresponding to the vertical direction of the grid pattern and a groove portion CC 4  engraved between the contact portions CV 4 . 
         [0067]    By the second cliche C 4 , the pattern region having the grid shape as illustrated in  FIG. 6  finally remains on the blanket B. That is, the square shape of the pattern region is formed by a region where the first groove portion and the second groove portion overlap each other. 
         [0068]    Meanwhile, a width L 4  of the groove portion CC 3  of the first cliche C 3  may be the same as a vertical width L 4  (see  FIG. 6 ) of the squares arranged in the grid pattern desired to be transferred to the substrate. 
         [0069]    Further, a width L 3  of the groove portion CC 4  of the second cliche C 4  may be the same as a horizontal width L 3  of the squares arranged in the grid pattern desired to be transferred to the substrate. 
       EXAMPLE 3 
       [0070]    The present invention may be applied to a case where the pattern desired to be finally transferred to the substrate has a random shape as well as a case where the pattern has a particular shape as described above. 
         [0071]    That is, as illustrated in  FIG. 9 , when it is desired to form a pattern  300  having a random shape on the substrate S, a first cliche C 5  illustrated in  FIG. 10  and a second cliche C 6  illustrated in  FIG. 11  may be used. 
         [0072]    The first cliche C 5  and the second cliche C 6  divide the pattern  300  having the random shape by a random line LN, and then separately perform removal for respective shear regions Ii and Ij having divided shapes  310  and  320 . 
         [0073]    That is, a groove portion CC 5  is formed only on a part corresponding to the shear region Ii of the first cliche C 5  in order to first remove the divided shape  310  corresponding to a left side of  FIG. 9 . 
         [0074]    Further, a groove portion CC 6  is formed only on a part corresponding to the shear region Ij of the second cliche C 6  in order to remove the divided shape  320  corresponding to a right side of  FIG. 9 . 
         [0075]    By such a cliche, the random shape may also be separately removed for respective shear regions. 
         [0076]    The pattern which a user desires may be finally transferred to the substrate S by transferring the functional ink to the cliche C separately for each shear region by using the cliche C of the present invention as described above, and then transferring the functional ink remaining on the blanket B to the substrate S. 
         [0077]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.