Abstract:
The present invention provides a method for applying a film in which non-contact repulsive forces generated by ultrasonic vibration are applied using an ultrasonic vibration unit (A) to a surface of a substrate so as to support the surface of the substrate without contact, and a film is pressed and applied to the other surface of the substrate using a pressing roller. The ultrasonic vibration unit (A) may comprise: an ultrasonic vibration body facing a surface of the substrate; and an ultrasonic excitement unit for exciting the ultrasonic vibration body. In addition, the present invention provides an apparatus for applying a film comprising: an ultrasonic vibration unit (A) for applying non-contact repulsive forces generated by the ultrasonic vibration to a surface of a substrate so as to support the surface of the substrate without contact; and a pressing roller for pressing and applying a film to the other surface of the substrate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a film lamination method and apparatus, and more particularly, to a film lamination method and apparatus able to support one surface of a substrate without contact and simultaneously laminate the other surface of the substrate with a film. 
         [0003]    2. Description of Related Art 
         [0004]    In some cases, the surface of a substrate is laminated with a film for some reason. For example, one surface of the substrate is laminated with a protective film in order to prevent the substrate surface from scratches or stains, or is laminated with a functional film for a special use. 
         [0005]      FIG. 1  schematically illustrates a method of laminating both surfaces of a substrate S with films F in the related art. 
         [0006]    As illustrated in  FIG. 1 , although only one surface of the substrate S is required to be laminated with a film F, both surfaces of the substrate S are laminated with a film F in order to prevent the other surface of the substrate S from being damaged. The films F are unnecessarily used on the both surfaces of the substrate S, thereby increasing consumable costs, which is problematic. 
         [0007]      FIG. 2  and  FIG. 3  illustrate a method of laminating one surface of a substrate S with a film F in the related art. 
         [0008]    When the surface quality of a substrate S is relatively less important, one surface (a B-side surface) of the substrate S is laminated with a film F by pressing the film F against the B-side surface of the substrate S using a pressure roller, and the other surface (an A-side surface) of the substrate S is supported on rollers formed of a soft material (e.g. silicone) by bringing the A-side surface of the substrate S into contact with the soft rollers. However, as the line is continuously used, the soft rollers are stained and damaged, thereby causing the A-side surface of the substrate S to suffer from damages, such as scratches or stains, as mentioned above. 
         [0009]      FIG. 4  illustrates another method of laminating one surface of a substrate S with a film F in the related art. 
         [0010]    The surface of an A-side pressure roller  10   a  that comes into contact with a substrate S is kept clean through rolling-contact with a sticky roller  10   c . However, in this case, a sticky material from the sticky roller  10   c  may be transferred to the surface of the substrate S through the pressure roller  10   a , thereby causing defects such as stains. Unexplained reference numeral  10   b  indicates another pressure roller. 
         [0011]      FIG. 5  illustrates a further method of laminating one surface of a substrate S with a film F in the related art. 
         [0012]    This method is similar to the related-art film lamination method illustrate in  FIG. 1 , except that the film F attached to the A-side surface of the substrate S is detached therefrom. In this case, however, an adhesive material from the film F is transferred to the surface of the substrate S, thereby staining the substrate S, which is problematic. In addition, the continuous use of the film F to be detached causes an increase in manufacturing costs, which is problematic. 
         [0013]    In the meantime, a technology for supporting the A-side surface of the substrate S without contact by combining a non-contact technology such as air floating was proposed. In this case, however, excessive utility costs are incurred. In addition, when a predetermined amount of pressure is applied in order to bond the film F to the substrate S, the air may not have a sufficient amount of repelling force, which frequently leads to the problem in that the substrate S comes into contact with the roller. Furthermore, the surface of the substrate S may be stained by the air. 
         [0014]    The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    Various aspects of the present invention provide a film lamination method and apparatus able to reliably laminate one surface of a substrate with a film while preventing both surfaces of the substrate from damages such as scratches or stains. 
         [0016]    In an aspect of the present invention, provided is a film lamination method including: supporting one surface of a substrate without contact by generating ultrasonic vibrations from an ultrasonic vibration unit and applying repelling force induced from the ultrasonic vibrations onto the one surface of the substrate; and simultaneously laminating the other surface of the substrate with a film by pressing the film against the other surface of the substrate using a pressure roller. 
         [0017]    The ultrasonic vibration unit may include a first ultrasonic vibration part disposed upstream of the pressure roller and a second ultrasonic vibration part disposed downstream of the pressure roller. 
         [0018]    In another aspect of the present invention, provided is a film lamination apparatus including: an ultrasonic vibration unit supporting one surface of a substrate without contact by applying repelling force induced from ultrasonic vibrations onto the one surface of the substrate; and a pressure roller laminating the other surface of the substrate with a film by pressing the film against the other surface of the substrate. 
         [0019]    According to the present invention as set forth above, it is possible to reliably laminate one surface of a substrate with a film while preventing both surfaces of the substrate from damages such as scratches or stains. It is therefore possible to half the use of consumables while allowing the substrate to have superior surface quality, thereby increasing the cost competitiveness of products. 
         [0020]    The methods and apparatuses of the present invention have other features and advantages that will be apparent from or are set forth in greater detail in the accompanying drawings which are incorporated herein, and in the following Detailed Description of the Invention, which together serve to explain certain principles of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  schematically illustrates a method of laminating either surface of a substrate with a film in the related art; 
           [0022]      FIG. 2  and  FIG. 3  illustrate a method of laminating one surface of a substrate with a film in the related art; 
           [0023]      FIG. 4  illustrates another method of laminating one surface of a substrate with a film in the related art; 
           [0024]      FIG. 5  illustrates a further method of laminating one surface of a substrate with a film in the related art. 
           [0025]      FIG. 6  schematically illustrates a first exemplary embodiment of a film lamination method according to the present invention; 
           [0026]      FIG. 7  schematically illustrates the ultrasonic vibration unit shown in  FIG. 6 ; 
           [0027]      FIG. 8  is a graph illustrating the relationship between the distance from the ultrasonic vibration unit to the substrate and the repelling force; 
           [0028]      FIG. 9  to  FIG. 11  schematically illustrate a second exemplary embodiment of the film lamination method according to the present invention; 
           [0029]      FIG. 12  schematically illustrates a third exemplary embodiment of the film lamination method according to the present invention; 
           [0030]      FIG. 13  schematically illustrates a fourth exemplary embodiment of the film lamination method according to the present invention; 
           [0031]      FIG. 14  schematically illustrates a fifth exemplary embodiment of the film lamination method according to the present invention; 
           [0032]      FIG. 15  schematically illustrates a sixth exemplary embodiment of the film lamination method according to the present invention; 
           [0033]      FIG. 16  schematically illustrates a seventh exemplary embodiment of the film lamination method according to the present invention; 
           [0034]      FIG. 17  schematically illustrates a film cutting process in the method shown in  FIG. 16 , in which a film is cut at a position between two single substrates; 
           [0035]      FIG. 18  to  FIG. 22  schematically illustrate an eighth exemplary embodiment of the film lamination method according to the present invention; 
           [0036]      FIG. 23  schematically illustrates a ninth exemplary embodiment of the film lamination method according to the present invention; and 
           [0037]      FIG. 24  and  FIG. 25  schematically illustrate a process in which a film is adhered to the pressure roller in a tenth exemplary embodiment of the film lamination method according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    Reference will now be made in detail to exemplary embodiments of the present invention in conjunction with the accompanying drawings so that a person skilled in the art to which the present invention relates could easily put the present invention into practice. 
         [0039]    Throughout this document, reference should be made to the drawings, in which the same reference numerals and symbols are used throughout the different drawings to designate the same or similar components. In the following description of the present invention, detailed descriptions of known functions and components incorporated herein will be omitted in the case that the subject matter of the present invention is rendered unclear. 
         [0040]      FIG. 6  schematically illustrates a first exemplary embodiment of a film lamination method according to the present invention. 
         [0041]    Herein, a substrate S to be laminated with a film F may be a glass substrate. The substrate S may also be formed of a flexible material or a hard material. The film lamination method illustrated in  FIG. 6  may be used for the substrate S formed of a flexible material, whereas a film lamination method illustrated in  FIG. 16  may be used for the substrate S formed of a hard material. 
         [0042]    When the substrate S is a thin glass substrate (having a thickness of 0.2 mm or less), the film lamination method may be implemented as a continuous process since the substrate S is flexible. Such a flexible substrate continuous in the lengthwise direction is referred to as a web. The web may be subjected to other continuous processes, such as machining and printing, in addition to the film lamination method according to the present invention. 
         [0043]    The film lamination apparatus illustrated in  FIG. 6  includes an (A-side or first) ultrasonic vibration unit and a (B-side) pressure roller. 
         [0044]    The ultrasonic vibration unit generates ultrasonic vibrations. The ultrasonic vibration unit employs an ultrasonic vibration technology (Korean Patent Application Publication No. 10-2010-0057530). The ultrasonic vibration unit supports one surface (A-side surface) of the substrate S without contact by applying non-contact repelling force induced from the ultrasonic vibrations to the one surface of the substrate S. The ultrasonic vibration unit includes a first ultrasonic vibration part  211  disposed upstream of the pressure roller  110  and a second ultrasonic vibration part  212  disposed downstream of the pressure roller  110 . Herein, the terms “upstream” and “downstream” are based on a path along which the substrate S is transported. 
         [0045]    The pressure roller  110  laminates the other surface (B-side surface) of the substrate S with a film F by pressing the film F against the other surface. The pressure roller  110  applies a pressure to the substrate S laminated with the film F such that one surface of the substrate S has a positive curvature (and thus the other surface of the substrate S has a negative curvature). At least one portion of the surface of the ultrasonic vibration parts  211 ,  212  facing the substrate S is a curved surface, the curvature of which corresponds to the positive curvature of one surface of the substrate S. 
         [0046]    The contact pressure force (FPR: Force from Pressure Roller) from the pressure roller  110  and non-contact repelling force (holding force) F 1  and F 2  from the ultrasonic vibration parts  211 ,  212  are applied to both surfaces of the substrate S in a balanced state. In order to prevent a brittle material such as thin glass, the pressure roller  110  and the ultrasonic vibration parts  211 ,  212  are configured to smoothly press the substrate S. In addition, the amount of the contact pressure force FPR of the pressure roller  110  and the amount of the non-contact repelling force of the ultrasonic vibration parts  211 ,  212  may be adjusted in a corresponding manner. 
         [0047]    Table 1 below presents the results obtained by comparing the film lamination method of the present invention with the film lamination methods of the related art. 
         [0000]    
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                 Roller &amp;  
               
               
                   
                   
                   
                   
                 ultrasonic 
               
               
                   
                   
                   
                   
                 vibration 
               
               
                   
                   
                 Roller &amp; 
                 Film 
                 unit 
               
               
                   
                 Roller &amp; 
                 sticky 
                 lamination &amp; 
                 (the present 
               
               
                   
                 roller 
                 roller 
                 delamination 
                 invention) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Contact 
                 Roller 
                 Roller 
                 Film 
                 None 
               
               
                 with A-side  
                   
                   
                   
                   
               
               
                 surface 
                   
                   
                   
                   
               
               
                 Scratch 
                 High 
                 Medium 
                 Low 
                 None 
               
               
                 Stain 
                 High 
                 Medium 
                 Low 
                 None 
               
               
                   
                   
                 (transfer 
                   
                   
               
               
                   
                   
                 of adhesive 
                   
                   
               
               
                   
                   
                 component) 
                   
                   
               
               
                 Cost 
                 None 
                 Medium 
                 High 
                 None 
               
               
                 Conclusion 
                 Bad 
                 Average 
                 Good 
                 Excellent 
               
               
                   
               
             
          
         
       
     
         [0048]    As apparent from Table 1 above, the film lamination method according to the present invention does not create scratches on the A-side surface of the substrate S that is not laminated with a film F since the A-side surface is not subjected to any mechanical contact. In addition, no stain is created since neither the adhesive tape nor the film is used. Furthermore, it is an advantageous in that there is no cost for consumables. Since a film F is interposed between the B-side surface of the substrate S and the pressure roller  110 , no damage is caused to the B-side surface of the substrate S. 
         [0049]    Although not shown, it is preferable that the substrate S is unwound from an unwinding roll, is laminated with the film F, and subsequently is wound on a winding roll (roll-to-roll process). 
         [0050]      FIG. 7  schematically illustrates one of the ultrasonic vibration parts  211 ,  212  shown in  FIG. 6 . 
         [0051]    The ultrasonic vibration part  211 ,  212  includes an ultrasonic vibrator  201  (e.g. an ultrasonic vibration table) facing one surface of the substrate S and an ultrasonic wave generator  203  for vibrating the ultrasonic vibrator. The ultrasonic vibration part  211 ,  212  further includes a frame  205  supporting the ultrasonic vibrator  201 . The ultrasonic vibration part  211 ,  212  further include vibration absorbers  207  disposed between the ultrasonic vibrator  201  and the frame  205  to block the transfer of vibrations from the ultrasonic vibrator  201  to the frame  205 . Ultrasonic vibrations create an air layer having a predetermined amount of pressure on the surface of the ultrasonic vibrator  201 . The air layer forms repelling force that reliably pushes the substrate S without any mechanical contact, thereby preventing the substrate surface from being damaged. 
         [0052]      FIG. 8  is a graph illustrating the relationship between the distance from the ultrasonic vibration parts  211 ,  212  to the substrate S and the repelling force. 
         [0053]    The smaller the distance between the ultrasonic vibration parts  211 ,  212  and the substrate S is, the greater the pressure of the air layer becomes. It is therefore possible to create a predetermined amount of pressure by which the substrate S can be laminated with a film F while the distance between the pressure roller  110  and the ultrasonic vibration parts  211 ,  212  is reduced. The high pressure of the air layer can prevent the substrate S from coming into contact with the ultrasonic vibration parts  211 ,  212 . 
         [0054]      FIG. 9  to  FIG. 11  schematically illustrate a film attachment process of a second exemplary embodiment of the film lamination method according to the present invention. 
         [0055]    A film lamination apparatus employed in this exemplary embodiment further includes an (B-side or second) ultrasonic vibration unit  300 , transportation rollers  400 , an unwinding roll  120  and a force applying unit  130  for applying a constant force disposed on the B side, in addition to the ultrasonic vibration parts  211 ,  212  disposed on the A side and the pressure roller  110  disposed on the B side. 
         [0056]    The B-side ultrasonic vibration unit  300  is disposed upstream of the pressure roller  110 . The film lamination apparatus generates ultrasonic vibrations using the B-side ultrasonic vibration unit  300  and applies non-contact repelling force induced from the ultrasonic vibrations to the other surface (B-side surface) of the substrate S, thereby supporting the other surface of the substrate S without contact. 
         [0057]    The transportation rollers  400  are disposed downstream of the pressure roller  110 . The transportation rollers  400  transport the substrate S through contact with the film F attached to the other surface of the substrate S. 
         [0058]    The unwinding roll  120  disposed on the B side supplies the film F to the other surface (B-side surface) of the substrate S by unwinding the film F therefrom. 
         [0059]    The force applying unit  130  applies a constant force to the pressure roller  110  in the direction toward the substrate S, such that a constant amount of contact pressure force is applied to the film F and the substrate S. Although the force applying unit  130  is illustrated as a cylinder in  FIG. 9  to  FIG. 11 , this is not intended to be limiting. A variety of alternative forms, such as a weight or a spring, may be used. 
         [0060]    Referring to the film lamination method, as illustrated in  FIG. 9 , the substrate S and the film F are transported or supplied to a position where the substrate S is laminated with the film F. Afterwards, as illustrated in  FIG. 10 , the pressure roller  110  is lifted upwards to apply pressure to the film F and the substrate S. Subsequently, as illustrated in  FIG. 11 , the film lamination method is carried out continuously by transporting the substrate S and the film F in the pressed state. 
         [0061]      FIG. 12  schematically illustrates a third exemplary embodiment of the film lamination method according to the present invention. 
         [0062]    The A-side ultrasonic vibration unit further includes a third ultrasonic vibration part  213  disposed on the A side. The third ultrasonic vibration part  213  is disposed at a position facing the pressure roller  110  such that the substrate S is positioned between the third ultrasonic vibration part  213  and the pressure roller  110 . A force applying unit  230  is disposed on the A-side to apply a constant force to the third ultrasonic vibration part  213  in the direction toward the substrate S. 
         [0063]    The film lamination apparatus further includes a dancer roller  150  for adjusting the tension of the film F. 
         [0064]      FIG. 13  schematically illustrates a fourth exemplary embodiment of the film lamination method according to the present invention. 
         [0065]    The film lamination apparatus illustrated in  FIG. 13  includes a positioning device  140  for the force applying unit  130  and the positioning devices  241 ,  242 ,  340  positioning for the ultrasonic vibration parts  211 ,  212 , and the ultrasonic vibration unit  300 . The position of the force applying unit  130  can be adjusted using the positioning device  140  for the force applying unit. The position of the ultrasonic vibration parts  212 ,  212 , and the ultrasonic vibration unit  300  can be adjusted using the positioning device  241 ,  242 ,  340  for the ultrasonic vibration parts  212 ,  212 , and the ultrasonic vibration unit  300 . 
         [0066]    In addition, the film F may be cut using a cutting device provided upstream of the pressure roller  110  on the path along which the film F is supplied. Another cutting device may also be disposed at a position facing the pressure roller  110  in order to cut the front and end portions of the film F. 
         [0067]      FIG. 14  schematically illustrates a fifth exemplary embodiment of the film lamination method according to the present invention, and  FIG. 15  schematically illustrates a sixth exemplary embodiment of the film lamination method according to the present invention. 
         [0068]    As illustrated in  FIG. 14  and  FIG. 15 , it is possible to design the film lamination method such that a film F can be attached to a variety of portions of a substrate S, such as a horizontal surface, a vertical surface, an upper surface, a lower surface, a left surface or a right surface. 
         [0069]      FIG. 16  schematically illustrates a seventh exemplary embodiment of the film lamination method according to the present invention, in which a (non-continuous) single substrate S formed of a hard material is laminated with a film F. 
         [0070]    The film lamination apparatus includes a cutting device  500  for cutting the film F. The cutting device  500  is disposed at a position downstream of the pressure roller  110 , facing the other surface of the substrate S. The ultrasonic vibration unit at the A-side includes a fourth ultrasonic vibration part  214  disposed on the A side, at a position facing the cutting device  500  such that the substrate S is positioned between the fourth ultrasonic vibration part  214  on the A side and the cutting device  500  on the B side. The fourth ultrasonic vibration part  214  facing the cutting device  500  serves to prevent the film F from being dislodged from its position. 
         [0071]      FIG. 17  schematically illustrates a film cutting process in the method shown in  FIG. 16 , in which a film F is cut at a position between two single substrates S. The film F is cut using the cutting device  500  at the position between the two single substrates S. 
         [0072]      FIG. 18  to  FIG. 22  schematically illustrate an eighth exemplary embodiment of the film lamination method according to the present invention. 
         [0073]    The substrate S is floated above the B-side ultrasonic vibration unit  300  and is transported in that state to a position where the substrate S is laminated with a film F. At this time, the pressure roller  110  fixes the film F in a predetermined position using a suitable means such as a vacuum pressure. The predetermined position is set to the position in which the substrate S is laminated with the film F ( FIG. 18 ). 
         [0074]    When the substrate S arrives at a position between the pressure roller  110  and the A-side ultrasonic vibration part  213 , the pressure roller  110  attaches the film F to the surface of the substrate S while rotating, and the ultrasonic vibration part  213  applies repelling force to the substrate S while maintaining a predetermined distance from the substrate S ( FIG. 19 ). 
         [0075]    When the process of laminating one substrate S with the film F is completed, the next substrate S arrives at the position between the pressure roller  110  and the A-side ultrasonic vibration part  213  while maintaining a predetermined distance from the preceding substrate S, and the above-described lamination is carried out ( FIG. 20  and  FIG. 21 ). 
         [0076]    When the two substrates S are transported at the predetermined distance therebetween, the portion of the film F between the two substrates S is cut at a predetermined position using the cutting device  500  ( FIG. 22 ). 
         [0077]    Although it has been described herein that the substrates S are transported for the sake of explanation, it is possible to laminate the substrates S with the film F by moving the pressure roller  110  in the state in which the substrates S are set stationary. 
         [0078]    According to the film lamination method illustrated in  FIG. 21 , the size of the film F is greater than the size of the substrate S laminated with the film F. In order to set the size of the film F to be smaller than the size of the substrate S laminated with the film F, the cutting device may be disposed at a position facing the outer circumference of the pressure roller  110 . 
         [0079]      FIG. 23  schematically illustrates a ninth exemplary embodiment of the film lamination method according to the present invention. 
         [0080]    The ultrasonic vibration parts of the ultrasonic vibration unit may have a variety of shapes such as an arc, a circle and a flat table. The ultrasonic vibration part  213  in the shape of a flat table may facilitate the alignment between the pressure roller  110  and the ultrasonic vibration part  213 . 
         [0081]    The film lamination method illustrated in  FIG. 16  to  FIG. 23  may be used to laminate a single substrate S formed of a hard material with a film F. 
         [0082]      FIG. 24  and  FIG. 25  schematically illustrate a process in which a film F is adhered to the pressure roller  110  in a tenth exemplary embodiment of the film lamination method according to the present invention. 
         [0083]    The pressure roller  110  has a plurality of air suction holes  111  in the outer circumference thereof that is in contact with the film F. This configuration helps the film F in the initial attachment position come into close contact with the pressure roller  110 , thereby facilitating the supply of the film F. 
         [0084]    The foregoing descriptions of specific exemplary embodiments of the present invention have been presented with respect to the drawings. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible for a person having ordinary skill in the art in light of the above teachings. 
         [0085]    It is intended therefore that the scope of the present invention not be limited to the foregoing embodiments, but be defined by the Claims appended hereto and their equivalents.