Abstract:
A described technology relates generally to a thin-film deposition mask assembly of a flat panel display for correcting form distortion caused by tension of a division mask. The thin-film deposition mask assembly includes: a frame for forming a penetrated opening; a first change compensating member and a second change compensating member disposed across the opening, fixed to a free end member formed by partially cutting the frame from the opening, and arranged as a pair; and a plurality of division masks being disposed to cross the first change compensating member and the second change compensating member on top sides of the first change compensating member and the second change compensating member.

Description:
RELATED APPLICATIONS 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0126210 filed in the Korean Intellectual Property Office on Dec. 17, 2009, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The described technology relates generally to a thin-film deposition mask assembly of a flat panel display. More particularly, the described technology relates generally to a thin-film deposition mask assembly of a flat panel display for attaching a division mask in a mask frame. 
     2. Description of the Related Art 
     Conventionally, flat panel displays include organic light emitting displays, liquid crystal displays (LCD), and plasma display panels (PDP). Manufacturing of an organic light emitting diode (OLED) display includes a process for forming an electrode and an organic emission layer with a thin film of a specific pattern. A mask assembly is used for the thin-film deposition process. 
     For example, the mask assembly includes a mask frame forming an opening, belt-type division masks fixed to the mask frame while tension is applied thereto in the length direction, and sub-masks intercepting neighboring division masks. The division mask includes a plurality of pattern openings to manufacture a plurality of organic light emitting diode (OLED) displays on a substrate array. Each pattern opening corresponds to one organic light emitting diode (OLED) display, and it is formed in the same pattern as the electrode or organic emission layer to be formed on the organic light emitting diode (OLED) display. 
     As the mask assembly has been enlarged, the length of the division mask has also been increased. Hence, the division mask is increased to remain behind because of gravity, and it becomes difficult to align the division mask and the mask frame, and the mask assembly and the substrate array. To reduce the division mask&#39;s to such remaining, tension is applied to the division mask. Therefore, tension is substantially applied to both sides of the frame, and the mask frame is bent inwardly in the tension&#39;s vertical direction. That is, a form distortion, such as, a saddle type of distortion occurs in the mask assembly. The form distortion of the mask assembly generates a position error of the pattern from the pattern opening of the division mask, and further increases the error. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology 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 
     The described technology has been made in an effort to provide a thin-film deposition mask assembly of a flat panel display for correcting form distortion caused by tension of a division mask. 
     An exemplary embodiment provides a thin-film deposition mask assembly of a flat panel display including: a frame for forming a penetrated opening; a first change compensating member and a second change compensating member disposed across the opening, fixed to a free end member formed by partially cutting the frame from the opening, and arranged as a pair; and a plurality of division masks being disposed to cross the first change compensating member and the second change compensating member on top sides of the first change compensating member and the second change compensating member, being fixed to both sides of the opening to receive tension in a length direction, being fixed to the first change compensating member and the second change compensating member to receive tension in a width to direction, and forming a pattern opening. 
     The free end member is divided into a first cut space formed in the width direction of the division mask in the opening so as to compensate transformation of the frame formed in the length direction of the first change compensating member and the second change compensating member, and a second cut space formed in the length direction of the division mask in the first cut space. 
     The free end member includes a first free end member and a second free end member formed on both sides of the frame corresponding to both sides of the first change compensating member and the second change compensating member. 
     The first free end member and the second free end member include a third free end member and a fourth free end member respectively connected to the first change compensating member and the second change compensating member. 
     The third free end member and the fourth free end member share the first cut space, and are set by connecting the second cut space. 
     The thin-film deposition mask assembly includes a micrometer having a first terminal connected to the free end member, being installed in the frame passing over the second cut space, and controlling a gap of the second cut space. 
     The micrometer includes a first micrometer and a second micrometer installed in a first free end member and a second free end member formed on both sides of the frame corresponding to both sides of the first change compensating member and the second change compensating member. 
     The micrometer includes a third micrometer and a fourth micrometer respectively installed in a third free end member and a fourth free end member respectively connected to the first change compensating member and the second change compensating member. 
     The free end member includes a receiving groove for fixing both sides of the first change compensating member and the second change compensating member, and the depth of the receiving groove corresponds to the thickness of the change compensating member. 
     According to an embodiment, a first change compensating member and a second change compensating member are installed by providing a free end member in an opening of a frame, a division mask is fixed to the frame to apply tension in the length direction and simultaneously the same is fixed to the first and second change compensating members to apply tension in the width direction, and hence, form distortion of the division mask in the width direction is corrected even though the form of the frame is distorted by the length-directional tension of the division mask. Therefore, generation of a position error of a pattern at a pattern opening of a division mask can be prevented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an exploded perspective view of a thin-film deposition mask assembly of a flat panel display according to a first exemplary embodiment. 
         FIG. 2  shows a top plan view of a thin-film deposition mask assembly of a flat panel display shown in FIG. I. 
         FIG. 3  shows a cross-sectional view with respect to a line III-III shown in  FIG. 2 . 
         FIG. 4  shows an exploded perspective view of a part in which a first change compensating member and a second change compensating member are fixed to a mask frame. 
         FIG. 5  shows a perspective view of a state in which a first change compensating member and a second change compensating member are welded in a mask frame. 
         FIG. 6  shows a state diagram of a compensation operation of a first change compensating member and a second change compensating member in a mask frame. 
         FIG. 7  shows an exploded perspective view of a part in which a first change compensating member and a second change compensating member are fixed to a mask frame in a thin-film deposition mask assembly of a flat panel display according to a second exemplary embodiment. 
         FIG. 8  shows a state diagram in which a micrometer is installed in a mask frame. 
         FIG. 9  shows a schematic diagram of a flat panel display deposition process using a thin-film deposition mask assembly of a flat panel display according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The exemplary embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments 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. 
       FIG. 1  shows an exploded perspective view of a thin-film deposition mask assembly of a flat panel display according to a first exemplary embodiment,  FIG. 2  shows a top plan view of a thin-film deposition mask assembly of a flat panel display shown in  FIG. 1 , and  FIG. 3  shows a cross-sectional view with respect to a line III-III shown in  FIG. 2 . 
     Referring to  FIG. 1  to  FIG. 3 , the thin-film deposition mask assembly  100  (for convenience, mask assembly) of a flat panel display according to the first exemplary embodiment includes a frame  20  having a penetrated opening  201 , at least one pair of a first change compensating member and a second change compensating member  31  and  32  fixed to the frame  20 , and a plurality of division masks  40  having a plurality of pattern openings  401  for deposition and being fixed to the frame  20  and the first and second change compensating members  31  and  32 . 
     For example, the frame  20  is formed to be a quadrangle corresponding to a substrate array  14  (refer to  FIG. 9 ) to be deposited, and includes a quadrangular opening  201  to be deposited on the substrate array  14 . That is, the frame  20  is entirely formed to be a quadrangular frame. 
     The division mask  40  receives tension and is fixedly installed in the frame  20 . Therefore, the frame  20  receives compressive force that is a reaction to the tension in the length direction (i.e., x-axis direction) of the division mask  40 . For example, the frame  20  can be made of metallic material with great rigidity so as to minimize the change caused by the compressive force. 
     The first and second change compensating members  31  and  32  are fixed to the frame  20  passing through the opening  201 . In the first exemplary embodiment, the first and second change compensating members  31  and  32  are disposed in parallel in the y-axis direction of the frame  20 . 
     The first and second change compensating members  31  and  32  can include a plurality of sets that are disposed with a gap in the length-wise direction (x-axis direction) of the division mask  40  according to a size of the frame  20 . By defining the one set according to the exemplary embodiment as one set, the first and second change compensating members  31  and  32  are configured with three sets and welded to the frame  20 . 
     The division mask  40  is formed to be a belt form with the width in the y-axis direction and the length in the x-axis direction, and includes pattern openings  401  is for manufacturing a unit organic light emitting diode (OLED) display (not shown). The pattern openings  401  are disposed in the length direction (x-axis direction) of the division mask  40 . The division masks  40  are repeatedly disposed in the y-axis direction to cover the entire opening  201  of the frame  20 . 
     The division masks  40  configured for the mask assembly  100  can suppress transformation of the division mask  40  and distortion of the pattern opening  401  caused by thermal expansion that may occur during deposition, and can minimize concentration of displacement on a specific part of the division mask  40  since they receive constant tension in the length direction (x-axis direction). 
     The pattern opening  401  provided in the division mask  40  corresponds to one display device, and the mask assembly  100  includes a plurality of pattern openings  401  in the x-axis direction and the y-axis direction of the division mask  40 . The pattern opening  401  is formed to be the same form of the electrode or emission layer to be formed on the organic light emitting diode (OLED) display. 
     The division mask  40  is fixed on the top surfaces of the first and second change compensating members  31  and  32 , and is fixed to the frame  20  on both sides of the opening  201 . In this instance, the division mask  40  receives tension in the x-axis direction and is fixed to the frame  20 , and it receives tension in the y-axis direction and is fixed to the one pair of the first and second change compensating members  31  and  32 . 
     The frame  20  includes a free end member  202  that is partially cut from the opening  201  and is then formed so as to correct y-axis directional form distortion of the division mask  40  fixed to the frame  20  even though the form of the frame is distorted in the y-axis direction because of the compressive force applied in the x-axis direction. The free end member  202  can be provided in the front or rear of the opening  201  of the frame  20 , and as shown in  FIG. 1 , it can be provided in both the front and the rear of the opening  201  of the frame  20 . 
     That is, the free end member  202  includes a first free end member (hereinafter, front free end member)  203  provided in the front of the frame  20  and a second free end member (hereinafter, rear free end member)  204  provided in the rear of the frame  20 , opposite the front free end member  203 , in correspondence to the first and second change compensating members  31  and  32 . Further, the front free end member  203  and the rear free end member  204  include a third free end member (hereinafter, left free end member)  205  connected to the first change compensating member  31  and a fourth free end member (hereinafter, right free end member)  206  connected to the second change compensating member  32 . The first change compensating member  31  is spot welded SP 5  to the left free end member  205 , and the second change compensating member  32  is spot welded SP 6  to the right free end member  206  (refer to  FIG. 6 ). 
       FIG. 4  shows an exploded perspective view of a part in which a first change compensating member and a second change compensating member are fixed to a mask frame, and  FIG. 5  shows a perspective view of a state in which a first change compensating member and a second change compensating member are welded in a mask frame. Referring to  FIG. 4  and  FIG. 5 , the free end member  202  is divided into a first cut space S 1  that is formed in the y-axis direction of the division mask  40  from the opening  201  and a second cut space S 2  that is formed in the x-axis direction of the division mask  40  in the first cut space S 1  so as to compensate transformation of the frame  20  formed in the y-axis direction of the first and second change compensating members  31  and  32 . For convenience of description, the front free end member  203  will be exemplarily described. 
     The left free end member  205  and the right free end member  206  share the first cut space S 1  provided therebetween, and have the second cut space S 2  on them. The left and right free end members can be set by independently forming the first cut space and the second cut space (not shown). Also, the left free end member  205  and right free end member  206  include receiving grooves  207  and  208  for receiving both ends of the first and second change compensating members  31  and  32  and fixing them (refer to  FIG. 4 ). The depths (H) of the receiving grooves  207  and  208  are formed to correspond to the thickness (T) of the first and second change compensating members  31  and  32 . When the first and second change compensating members  31  and  32  are fixed and installed in the receiving grooves  207  and  208 , top surfaces of the first and second change compensating members  31  and  32  and a top surface of the frame  20  approximately form a horizontal plane. Therefore, the division mask  40  can be installed horizontally (refer to  FIG. 5 ). 
       FIG. 6  shows a state diagram of a compensation operation of a first change compensating member and a second change compensating member in a mask frame. Referring to  FIG. 6 , the division mask  40  receives tension in the x-axis direction and is fixed to both sides of the frame  20  through spot welding SP 1  and SP 2 , and simultaneously receives tension in the y-axis direction and is fixed to the first and second change compensating members  31  and  32  through spot welding SP 3  and SP 4 . In this instance, the rear part in the y-axis direction of the division mask  40  is spot welded SP 3  to the first change compensating member  31  on the left, and while tension is applied in the y-axis direction, the front part is spot welded SP 4  to the second change compensating member  32  on the right. Hence, the division mask  40  receives tension in the y-axis direction. The division mask  40  is fixed through welding while positioned to be overlapped with the top side of the frame  20 , and it is then fixed on the top side. An outer part of the welding point of the division mask  40  is cut. 
     Referring to  FIG. 5 , when the division masks  40  receive tension in the y-axis direction and the width thereof is increased in the y-axis direction, reduction of width in the y-axis direction of the division masks  40  is compensated by form distortion DI in the y-axis direction of the frame  20 . That is, since width of the division masks  40  is transformed in the opposite direction of the distortion Dl of the frame  20 , distortion of the division mask  40  in the y-axis direction is compensated (D 2 ). In this instance, the left free end member  205  and the right free end member  206  compensate y-axis directional distortion by moving back from the solid line state to the imaginary line state D 2 . Therefore, a positional error of the pattern opening  401  can be reduced in the division mask  40 . 
     Another exemplary embodiment will be described. The same configurations as the first exemplary embodiment will be omitted, and a different configuration will be described. 
       FIG. 7  shows an exploded perspective view of a part in which a first change compensating member and a second change compensating member are fixed to a mask frame in a thin-film deposition mask assembly of a flat panel display according to a second exemplary embodiment, and  FIG. 8  shows a state diagram in which a micrometer is installed in a mask frame. 
     The first exemplary embodiment includes a free end member  202  of the frame  20  so as to fix the first and second change compensating members  31  and  32 . Therefore, the first exemplary embodiment compensates y-axis directional distortion with elasticity of the free end member  202  within the range of the second cut space S 2  for forming the free end member  202 . 
     Compared to this, in the second exemplary embodiment, the free end member  302  aggressively controls the second cut space S 2  to compensate for y-axis directional distortion of the free end member  302 . The mask assembly  200  according to the second exemplary embodiment further includes a micrometer  501  in the free end member  302 . The micrometer  501  has a first terminal connected to the free end member  302 , and it is installed in the frame  20  passing over the second cut space S 2  to control the gap of the second cut space S 2 . 
     The micrometer  501  includes a first micrometer (hereinafter, front micrometer)  502  and a second micrometer (hereinafter, rear micrometer)  503  installed in a front free end member  303  and a rear free end member  304  formed on both sides of the y-axis direction of the frame  20  corresponding to both sides of the first and second change compensating members  31  and  32 . The front micrometer  502  and the rear micrometer  503  include a third micrometer (hereinafter, left micrometer)  504  and a fourth micrometer (hereinafter, right micrometer)  505  installed in a left free end member  305  and a right free end member  306  connected to the first and second change compensating members  31  and  32 . 
     In the frame  20 , the first and second change compensating members  31  and  32  are fixed through spot welding SP 5  and SP 6  to the left free end member  305  and the right free end member  306  of the front free end member  303  and rear free end member  304 . Tension is applied in the x-axis direction to fix the division mask  40  to both sides of the frame  20  in the x-axis direction through spot welding SP 1  and SP 2 , and tension is applied in the y-axis direction to fix the division mask  40  to the first and second change compensating members  31  and  32  through spot welding SP 3  and SP 4 . 
     The left and right micrometers  504  and  505  installed in the left and right free end members  305  and  306  of the front and rear free end members  303  and  304  are controlled. Therefore, width of the division masks  40  is transformed in the opposite direction of distortion Dl of the frame  20  caused by tension of the division mask  40  to thus compensate the y-axis directional distortion D 2  of the division mask  40 . In this instance, the left free end member  305  and the right free end member  306  compensate the y-axis directional distortion D 2  while moving from the solid line state to the imaginary line state. 
       FIG. 9  shows a schematic diagram of a flat panel display deposition process using a thin-film deposition mask assembly of a flat panel display according to exemplary embodiments. Referring to  FIG. 9 , the mask assembly  100  is fixed to a frame holder  12  in a deposition device. A substrate array  14  is provided on the top parts of a plurality of division masks  40 . When electrode material or emission layer material is vaporized from a deposition source  16 , material is deposited on the substrate array  14  through the pattern opening  401  in a like form of the pattern opening  401 . Therefore, a plurality of flat panel displays, for example, a plurality of organic light emitting diode (OLED) displays, can be manufactured on a single substrate array  14  by using the mask assembly  100 . 
     The mask assembly  100  has been described in exemplary embodiments to form the electrode and the organic emission layer of an organic light emitting diode (OLED) display, and the exemplary embodiments are not restricted thereto. The mask assembly  100  is efficiently applicable to formation of electrodes of other flat panel displays. 
     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.