Abstract:
A laser sealing device includes a laser beam generation device for irradiating a laser beam, a shutter positioned on a beam path of the laser beam and for blocking a portion of the laser beam, and a substrate supporter for supporting a substrate on which a frit is formed, the frit being configured to be irradiated with the laser beam passing through the shutter, wherein the shutter has a circular aperture for transmitting the laser beam, and comprises a blocking portion defining a portion of the aperture.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0041404 filed in the Korean Intellectual Property Office on Apr. 20, 2012, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The described technology relates generally to a laser sealing device and a manufacturing method of an organic light emitting diode (OLED) display using the same. 
     2. Description of Related Art 
     An organic light emitting diode (OLED) display includes two electrodes and an organic light emitting element including an organic emission layer located between the two electrodes, wherein electrons injected from one electrode and holes injected from the other electrode are combined on the organic emission layer to form excitons that emit light while emitting energy. 
     The OLED display includes an element substrate formed with at least one organic light emitting element, an encapsulation substrate combined to the element substrate to encapsulate the organic light emitting element, and a frit to combine the element substrate and the encapsulation substrate. 
     If the element substrate is large, a frit having a wide width is used, which may require a uniform or near uniform temperature to melt the frit via a laser beam. If the temperature at which the frit is melted is not uniform, bubbles may be generated in areas where the temperature in the frit is higher, and/or an underlying metal wire may be damaged. 
     Accordingly, energy density of a center portion of the laser beam is decreased using a laser mask to achieve uniform temperature of the frit. However, the energy density of the center portion of the laser beam might not be easily decreased because of the high energy density at a periphery of the laser beam. 
     Also, for the uniform temperature of the frit, when the energy distribution of a circular flat top laser beam is changed from a Gaussian shape to a flat shape (the laser beam having a diameter that is larger than the width of the frit), the energy density in the laser beam irradiated to the frit center portion is larger than the energy density of the laser beam irradiated to the frit peripheral portion, such that the temperature of the frit center portion is higher than the temperature of the frit peripheral portion. In this case, the temperature of the center portion of the frit is increased such that bubbles may be generated, and when a metal wire is disposed under the frit, the metal wire might be expanded upward, or bulged, and the frit may be damaged. 
     Also, when using a quadrangle flat top laser beam to remove an imbalance of an incident energy density of the circular flat top laser beam, the energy in the frit peripheral portion, as compared with the frit center portion, is largely lost due to an edge effect, such that the temperature of the frit center portion is still high and the temperature of the frit is non-uniform. In this case, if the energy of the laser beam irradiated to the frit peripheral portion is increased to seal the frit peripheral portion, the metal wire might be damaged, and bubbles might be generated in the frit center portion, such that a micro crack may be generated. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology, and 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 
     Embodiments of the present invention provide a laser sealing device for suppressing damage to a metal wire under a frit, and suppressing bubble generation of a frit center portion, by forming a uniform temperature of a center portion and a peripheral portion of a frit to which a laser beam is irradiated, and a manufacturing method of an organic light emitting diode (OLED) display using the same. 
     A laser sealing device according to an exemplary embodiment includes a laser beam generation device for irradiating a laser beam, a shutter positioned on a beam path of the laser beam and for blocking a portion of the laser beam, and a substrate supporter for supporting a substrate on which a frit is formed, the frit being configured to be irradiated with the laser beam passing through the shutter, wherein the shutter has a circular aperture for transmitting the laser beam, and comprises a blocking portion defining a portion of the aperture. 
     The blocking portion may have a circular arc shape. 
     The blocking portion may have a trapezoidal shape. 
     The blocking portion may have a curved vertex. 
     A diameter of the aperture may be larger than a width of the frit. 
     A width of the blocking portion may be larger than the width of the frit. 
     The laser sealing device may further include an optical system at the beam path between the laser beam generation device and the substrate for controlling a shape of the laser beam. 
     The shutter may be positioned at the beam path between the optical system and the substrate. 
     The shutter may be a metallic material. 
     The shutter may be positioned at the beam path between the laser beam generation device and the optical system. 
     The laser beam generation device and the optical system may be coupled by a single fiber, and the shutter may be located at the single fiber. 
     The shutter may be a glass material. 
     The shutter may be positioned on the beam path inside the optical system. 
     The shutter may be positioned at a laser focusing portion inside the optical system. 
     The shutter may be a diffraction optical lens positioned at an outlet of the optical system. 
     A method of manufacturing an OLED display using a laser sealing device according to an exemplary embodiment includes mounting a substrate formed with a frit at a substrate supporter, positioning a shutter at the substrate, the shutter having a circular aperture and comprising a blocking portion, and irradiating a laser beam through the aperture to the frit. 
     A center axis of the blocking portion may be parallel to a scan direction of the laser beam. 
     The method may further include rotating the shutter when the laser beam reaches a corner portion of the substrate. 
     According to an exemplary embodiment, the blocking portion is formed at the aperture such that the energy density of the laser beam irradiated to the frit is easily controlled, and the temperature of the frit may be uniform. 
     Furthermore, discoloration of the frit center portion, generation of the bubble and the micro crack, and the damage to the metal wire under the frit may be suppressed. 
     Also, the center axis of the blocking portion is disposed parallel to the scan direction of the laser beam, and the energy density distribution of the laser beam is axis-symmetrical such that the laser beam is easily rotated in the corner portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a laser sealing device according to a first exemplary embodiment. 
         FIG. 2  is a top plan view of a shutter used in a laser sealing device according to the first exemplary embodiment. 
         FIG. 3  is a graph of a temperature distribution of a frit positioned corresponding to an upper blocking portion when performing a sealing process using a laser sealing device according to the first exemplary embodiment. 
         FIG. 4  is a graph of a temperature distribution of a frit positioned corresponding to a lower blocking portion when performing a sealing process using a laser sealing device according to the first exemplary embodiment. 
         FIG. 5  is a top plan view of a shutter used in a laser sealing device according to a second exemplary embodiment. 
         FIG. 6  is a top plan view of a shutter used in a laser sealing device according to a third exemplary embodiment. 
         FIG. 7  is an enlarged view of a shutter and an optical system of a laser sealing device according to a fourth exemplary embodiment. 
         FIG. 8  is an enlarged view of a shutter and an optical system of a laser sealing device according to a fifth exemplary embodiment. 
         FIG. 9  is an enlarged view of a shutter and an optical system of a laser sealing device according to a sixth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
     Like reference numerals designate like elements throughout the specification. 
     In addition, the size and the thickness of each element in the drawing may be random samples for better understanding and ease of description, and the present invention is not limited thereto. 
     Now, a laser sealing device according to the first exemplary embodiment will be described with reference to  FIGS. 1 to 4 . 
       FIG. 1  is a schematic view of a laser sealing device according to the first exemplary embodiment, and  FIG. 2  is a top plan view of a shutter used in a laser sealing device according to the first exemplary embodiment. 
     As shown in  FIGS. 1 and 2 , the laser sealing device according to the first exemplary embodiment includes a laser beam generation device  10  irradiating a laser beam  1 , a shutter  20  positioned on a beam path of the laser beam  1  and partially blocking the laser beam  1 , a substrate supporter  30  mounted with a substrate  100  in which a frit  300 , which is irradiated by the laser beam  1  passing through the shutter  20 , is formed, and an optical system  40  positioned on the beam path between the laser beam generation device  10  and the substrate  100 . Although the term “shutter” is used in the present application, shutters  20 ,  60 ,  70 , and  80  may be a plate or other solid piece of material, according to embodiments of the present invention. 
     A single fiber  50  (e.g., an optic fiber) is installed between the laser beam generation device  10  and the optical system  40  such that a transmission of the laser beam  1  is substantially uniform. That is, a transmission of the laser beam  1  to the optical system  40  through the single fiber  50  has a substantially uniform cross-section. In the present embodiment, a beam coupler  51  and/or a beam collimator  52  to help the transmission of the laser beam  1  is installed in the single fiber  50 . 
     The optical system  40  includes a cylindrically shaped lens barrel  41  and a plurality of lenses  42  interposed within the lens barrel  41 , thereby controlling the shape of the laser beam  1 . The laser beam  1  is circular and has a flat top due to the optical system  40 . In the present exemplary embodiment, the circular laser beam  1  has a diameter of 3.5 mm. 
     The shutter  20  is positioned on the beam path between the optical system  40  and the substrate  100 , and may be formed of a metallic material to be installed close to the substrate  100 . This shutter  20  is positioned at a focusing portion of the optical system  40  thereby blocking a portion of the circular laser beam  1 . When the shutter  20  is not close to the substrate  100 , the portion of the laser beam  1  might not be blocked to form a desired shape by a diffraction phenomenon. 
     As shown in  FIG. 2 , the shutter  20  has a circular aperture  20   a  through which the laser beam  1  is passed, and an upper portion and a lower portion of the aperture  20   a  have (e.g., are formed by) a blocking portion  21 . The blocking portion  21  has a circular arc shape and protrudes into the aperture  20   a . An upper blocking portion  211  and a lower blocking portion  212  are substantially symmetrical with reference to the center of the aperture  20   a.    
     The diameter d 1  of the aperture  20   a  may be larger than the width d 2  of the frit  300  and the width d 3  of the blocking portion  21  may be larger than the width d 2  of the frit  300 . In the present embodiment, the width d 3  of the blocking portion  21  may be about 10% larger than the width d 2  of the frit  300 , or more. Also, the width d 3  of the blocking portion  21  may be smaller than the diameter of the aperture  20   a . When the width d 3  of the blocking portion  21  is not larger than the width d 2  of the frit  300 , the shape of the laser beam  1  may be irregular due to the diffraction phenomenon caused by the edge portion of the blocking portion  21 . 
     When there is no blocking portion  21  in the aperture  20   a , the energy density of the center portion of the laser beam  1  irradiated to the frit  300  is larger than the energy density of the peripheral portion of the laser beam  1  irradiated to the frit  300 , however, as in the present exemplary embodiment, when the center portion of the laser beam  1  irradiated to the frit  300  through the aperture  20   a  is blocked by the blocking portion  21 , the energy density of the center portion of the laser beam  1  irradiated to the frit  300  is controlled to be the same as the energy density of the peripheral portion of the laser beam  1  irradiated to the frit  300 . Accordingly, the center portion of the frit  300  and the peripheral portion of the frit  300  irradiated with the laser beam  1  have a substantially uniform temperature such that bubble generation in the center portion of the frit  300 , as well as damage to the metal wire positioned under the frit  300 , may be reduced or prevented. 
       FIG. 3  is a graph of a temperature distribution of a frit position with respect to an upper blocking portion when performing a sealing process using a laser sealing device according to the first exemplary embodiment, and  FIG. 4  is a graph of a temperature distribution of a frit position with respect to a lower blocking portion when performing a sealing process using a laser sealing device according to the first exemplary embodiment. 
     In  FIGS. 3 and 4 , line A shows a temperature distribution of a frit  300  caused by a laser beam passing through an aperture  20   a  in which a blocking portion is not formed, line B shows a temperature distribution of a frit  300  caused by a laser beam passing through an aperture  20   a  having a crossing point Y 1 , where a blocking portion  21  meets with a vertical center axis Y of an aperture  20   a  at 20% of a radius of the aperture  20   a , a line C shows a temperature distribution of a frit  300  caused by a laser beam passing through an aperture  20   a  when the crossing point Y 1  of the blocking portion  21  is at 40% of the radius of the aperture  20   a , and a line D shows a temperature distribution of a frit  300  by a laser beam passing through an aperture  20   a  when the crossing point Y 1  of the blocking portion  21  is at 60% of the radius of the aperture  20   a.    
     As shown in  FIGS. 3 and 4 , when the crossing point Y 1  of the blocking portion  21  is positioned at more than 30% of the radius of the aperture  20   a , the temperature of the center portion of the frit  300  caused by the laser beam  1  is decreased such that the center portion of the frit  300  and the peripheral portion of the frit  300  have a substantially uniform temperature. 
     A manufacturing method of an organic light emitting diode (OLED) display using the laser sealing device according to the first exemplary embodiment will be described with reference to  FIGS. 1 and 2 . 
     As shown in  FIGS. 1 and 2 , in the manufacturing method of an OLED display using the laser sealing device according to the first exemplary embodiment, firstly, a substrate  100  formed with a frit  300  is mounted on a substrate supporter  30 . That is, to assemble an element substrate  110  and an encapsulation substrate  210 , the frit  300  is made as a paste and is coated with a reference thickness (e.g., a predetermined thickness) at a position to be assembled on the element substrate  110 . Next, the frit  300  coated on the element substrate  110  is pre-baked to remove moisture and a binder component in the frit  300 , and the encapsulation substrate  210  is aligned on the element substrate  110 . 
     Next, a laser sealing device including a shutter  20  having a circular aperture  20   a  for passing a laser beam  1  and including an upper blocking portion  211  and a lower blocking portion  212  is positioned on the substrate  100 . 
     Next, the laser beam  1  is irradiated and is changed, or shaped, by the blocking portion  21  of the shutter  20  to be irradiated and scanned to the frit  300 . As described above, a portion coated with the frit  300  is locally heated by the laser beam  1  to melt the frit  300  thereby performing a sealing process of assembling (combining) the element substrate  110  and the encapsulation substrate  210 . At this time, to avoid generation of the bubble in the center portion of the frit  300 , a center axis Y of the blocking portion  21 , that is, the vertical center axis Y of the aperture  20   a , is parallel to the scan direction of the laser beam  1 . 
     When the aperture  20   a  does not have the blocking portion  21 , the energy density of the center portion of the laser beam  1  irradiated to the frit  300  is larger than the energy density of the peripheral portion of the laser beam  1  irradiated to the frit  300 . However, as with the present exemplary embodiment, when the center portion of the laser beam  1  is blocked by the blocking portion  21 , the energy density of the center portion of the laser beam  1  irradiated to the frit  300  is controlled to be the same as the energy density of the peripheral portion of the laser beam  1  irradiated to the frit  300 . Accordingly, the center portion of the frit  300  and the peripheral portion of the frit  300  irradiated with the laser beam  1  have a substantially uniform temperature, such that the bubble generation in the center portion of the frit  300 , as well as damage to the metal wire positioned under the frit  300 , may be reduced or prevented. 
     When the laser beam  1  performs in a corner portion of the substrate  100 , the shutter  20  is rotated. At this time, the center axis Y of the blocking portion  21  is parallel to the scan direction of the laser beam  1 , and the energy density distribution of the laser beam  1  is substantially symmetrical, such that the rotation is easy in the corner portion. Accordingly, temperature of the center portion of the frit  300  and the peripheral portion of the frit  300  irradiated with the laser beam  1  is substantially uniform, such that the bubble generation in the center portion of the frit  300 , and damage to the metal wire positioned under the frit  300 , may be reduced or prevented. 
     A second exemplary embodiment and a third exemplary embodiment having different shapes from the blocking portion of the first exemplary embodiment are possible. 
       FIG. 5  is a top plan view of a shutter used in a laser sealing device according to the second exemplary embodiment, and  FIG. 6  is a top plan view of a shutter used in a laser sealing device according to the third exemplary embodiment. 
     The second exemplary embodiment and the third exemplary embodiment are substantially equivalent to the first exemplary embodiment shown in  FIGS. 1 and 2 , with the exception of the shape of the blocking portion. Accordingly, repeated description is omitted. 
     As shown in  FIG. 5 , the shutter  20  has a circular aperture  20   a  passing with the laser beam  1 , and the upper and lower portions of the aperture  20   a  have a blocking portion  22  having a trapezoidal shape and protrudes to the aperture  20   a . An upper blocking portion  221  and a lower blocking portion  222  are substantially symmetrical with respect to a horizontal axis of the aperture  20   a.    
     The diameter d 1  of the aperture  20   a  is larger than the width d 2  of the frit  300 , and the width d 3  of the blocking portion  22  may be larger than the width d 2  of the frit  300 . In the present embodiment, the width d 3  of the blocking portion  22  may be 10% (or more) larger than the width d 2  of the frit  300 . Also, the width d 3  of the blocking portion  22  may be smaller than the diameter d 1  of the aperture  20   a . When the width d 3  of the blocking portion  22  is not larger than the width d 2  of the frit  300 , the shape of the laser beam  1  may be irregular due to the diffraction phenomenon of the edge portion of the blocking portion  22 . 
     Also, as shown in  FIG. 6 , the shutter  20  of the third embodiment includes the circular aperture  20   a  for passing the laser beam  1 , and the upper and lower portions of the aperture  20   a  have a blocking portion  23 . The blocking portion  23  has a trapezoidal shape having a curved vertex, and protrudes into the aperture  20   a . An upper blocking portion  231  and a lower blocking portion  232  are substantially symmetrical with reference to the horizontal axis of the aperture  20   a.    
     In the present embodiment, the diameter d 1  of the aperture  20   a  is larger than the width d 2  of the frit  300 , and the width d 3  of the blocking portion  23  is also larger than the width d 2  of the frit  300 . In the present embodiment, the width d 3  of the blocking portion  23  may be 10% larger than the width d 2  of the frit  300  (or larger). Also, the width d 3  of the blocking portion  23  may be smaller than the diameter of the aperture  20   a.    
     A fourth exemplary embodiment, in which the shutter is differently located between the laser beam generation device and the optical system, is possible, differing from the shutter of the first exemplary embodiment, which is positioned on the beam path between the optical system and the substrate. 
       FIG. 7  is an enlarged view of a shutter and an optical system of a laser sealing device according to the fourth exemplary embodiment, which is substantially equivalent to the first exemplary embodiment shown in  FIGS. 1 and 2  with the exception of the shutter, and repeated description is omitted. 
     As shown in  FIG. 7 , a shutter  60  of the laser sealing device according to the fourth exemplary embodiment is positioned on the beam path between the laser beam generation device  10  and the optical system  40 , and may be made of a glass material. 
     In detail, the shutter  60  is installed as a single fiber  50  connecting the laser beam generation device  10  and the optical system  40 , and the shutter  60  may have blocking portions  21 ,  22 , and  23  described in the first exemplary embodiment to the third exemplary embodiment. The single fiber  50  uniformly transmits the circular laser beam  1  generated in the laser beam generation device  10  and the shutter  60  of the glass material is installed in the single fiber  50 , thereby obtaining the clean laser beam  1  having high efficiency. 
     The shutter  60  is rotated while maintaining the optical axis of the laser beam  1  as to avoid twisting when sealing the corner portion. 
     A fifth exemplary embodiment, in which the shutter is disposed inside the optical system, is possible, differing from the shutter of the first exemplary embodiment, which is positioned on the beam path between the optical system and the substrate. 
       FIG. 8  is an enlarged view of a shutter and an optical system of a laser sealing device according to the fifth exemplary embodiment, which is substantially equivalent to the first exemplary embodiment shown in  FIGS. 1 and 2 , except for the shutter, and repeated description is omitted. 
     As shown in  FIG. 8 , a shutter  70  of the laser sealing device according to the fifth exemplary embodiment may be positioned inside the optical system  40 . 
     In detail, the optical system  40  includes a plurality of lenses  42 , and the shutter  70  is positioned at the focusing portion of one of the lenses  42 . The optical system  40  shown in  FIG. 8  includes three lenses  42 , and the shutter  70  is positioned at the focusing portion of the second lens. The shutter  70  may have the blocking portions  21 ,  22 , and  23  described in the first to third exemplary embodiments. Accordingly, the laser beam  1  having the shape of the shutter  70  is formed at the frit  300 . 
     For the shutter  70  of the present embodiment, the blocking portions  21 ,  22 , and  23  are formed by depositing a blocking metal on quartz, and the blocking metal must be a material that is robust against a high intensity of the laser beam  1  in the focusing portion of the second lens. The blocking metal may be tungsten when the intensity of the laser beam  1  is in a range of 40 to 100 W. Also, the shutter  70  may be formed by directly laser-processing the blocking metal, and may be installed to be rotated when sealing the corner portion. 
     The fifth exemplary embodiment of a diffraction optical lens, in which the shutter is disposed at an outlet of the optical system, is possible, and is different from the shutter of the first exemplary embodiment positioned on the beam path between the optical system and the substrate. 
       FIG. 9  is an enlarged view of a shutter and an optical system of a laser sealing device according to a sixth exemplary embodiment, which is substantially equivalent to the first exemplary embodiment shown in  FIGS. 1 and 2 , with the exception of the shutter, and repeated description is omitted. 
     As shown in  FIG. 9 , a shutter  80  of the laser sealing device according to the sixth exemplary embodiment is positioned at the outlet of the optical system  40 , and may be a diffraction optical lens (DOE). 
     The shutter  80  is the diffraction optical lens such that the circular laser beam  1  is changed into the laser beam  1  of a different shape. 
     In this case, the first diffraction image is formed at an optical axis, and after the zero diffraction image is incident to be twisted by 2 to 3 degrees, if the laser beam power is more than 100 mW, the blocking is performed by using a mask, and a higher order diffraction image is processed as black noise. 
     While this disclosure 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, and their equivalents. 
     SOME OF THE REFERENCE CHARACTERS 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 10: laser generation device 
                 20, 60, 70, 80: shutter 
               
               
                   
                 21, 22, 23: blocking portion 
                 30: substrate supporter 
               
               
                   
                 40: optical system 
                 50: single fiber