Abstract:
A glass cutting method and glass for a flat panel display. This glass cutting method forms crack regions of a constant size and pitch inside the glass using a laser and performs the full-through cutting process along the crack regions with a laser, thereby increasing cutting edge quality, shortening the cutting time and reducing the production cost.

Description:
CLAIM OF PRIORITY 
       [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application earlier filed in the Korean Intellectual Property Office on 7 Aug. 2007 and there duly assigned Serial No. 10-2007-0078951. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to glass cutting method, glass for flat panel display thereof and flat panel display device using it. 
         [0004]    2. Description of the Related Art 
         [0005]    A plasma display device, for instance, forms a barrier rib and a phosphor layer between two thin substrates and injects an inert gas. Then, a high voltage is applied to the inert gas. As a result thereof, ultra-violet rays are emitted from an inert gas so as to excite the phosphor layer and the excited phosphor layer emits a visible ray. 
         [0006]    Further, an organic light-emitting display device sequentially forms a semiconductor layer and an organic light-emitting layer on the substrate and applies a predetermined current (or voltage) to the semiconductor layer, so that the organic light-emitting layer emits the visible ray. 
         [0007]    Additionally, a liquid crystal display device forms a semiconductor layer, a liquid crystal and a color filter and others between two thin substrates and applies a predetermined current (or voltage) to the semiconductor layer, so that light is emitted from the backlight to the outsurface through the color filter according to the molecular direction of the liquid crystal. 
         [0008]    As described above, a general flat panel display device has used, as a transparent substrate, a substrate, in which since the size of the mother glass is larger than the actual size of a display device to be manufactured (eg. 40″, 50″, 60″ and the like), it is required to perform a glass cutting process according to the size of the display device. 
         [0009]    Current glass cutting methods generally include a wheel cutting technique and a laser cutting technique. The wheel cutting technique is achieved by forming a scribe groove with a predetermined depth on the surface of the glass using a diamond wheel, and then mechanically warping the glass. Further, the laser cutting technique is also achieved by forming a scribe groove with a predetermined depth on the surface of the glass using laser, and then mechanically warping the glass. Ultimately, both these wheel and laser cutting techniques compulsively perform warping of the glass, so that great amounts of glass particles are generated during the cutting process. Such glass particles remain on the surface of the glass during a manufacturing process, thereby causing many defects. 
         [0010]    Accordingly, a full-through laser cutting technique has been recently used, and is a technique that performs the full-through cutting of the glass using laser without mechanical warping. However, since the full-through laser cutting technique performs the full-through cutting of the glass, it takes a long time to cut the glass. Additionally, since the fill-through laser cutting technique is equipped with a laser source with a high output power, there is an increase in production cost. In other words, the full-through laser cutting technique is advantageous to perform the glass cutting without glass particles, however, it needs long processing time and further increases production cost by using an expensive laser apparatus. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, an aspect of the present invention is to provide glass cutting method, glass for flat panel display thereof and flat panel display device using it that can increase cutting edge quality, shorten the cutting time and reduce the processing cost, by forming crack regions with a constant size and pitch inside the glass with a laser and performing the full-through cutting process along the crack regions with the laser. 
         [0012]    According to an aspect of the present invention, there is provided a glass cutting method for flat panel display device which may include forming crack region that outputs intermittently laser beams from a movable laser apparatus, so that crack regions are formed inside glass, and a full-through cutting that outputs continuously laser beams from the laser apparatus along the crack regions formed inside the glass so as to perform the full-through cutting of the glass. 
         [0013]    According to another aspect of the present invention, there is provided glass for flat panel display device which may include a first surface, a second surface opposite to the first surface, and a third surface connecting the first and second surfaces, wherein at least one crack region formed with a laser in order to be guided on the third surface. 
         [0014]    According to still another aspect of the present invention, there is provided a flat panel display device which may a first substrate, a display unit which is formed in the first substrate and indicates an image, and a second substrate which is formed on the top of the first substrate and seals the display unit hermetically, wherein at least one crack region is formed with a laser in order to be guided along the first substrate and the second substrate each outer peripheral surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicated the same or similar components, wherein: 
           [0016]      FIG. 1  is a flowchart illustrating a glass cutting method of one embodiment of the present invention; 
           [0017]      FIG. 2   a  is a plane diagram illustrating a status that crack regions are formed on the glass by laser in a glass cutting method of one embodiment of the present invention; 
           [0018]      FIG. 2   b  is a plane diagram illustrating a status that a cutting edge is formed on the glass along the crack regions with a laser in the glass cutting method of one embodiment of the present invention; 
           [0019]      FIG. 3  is a plane diagram illustrating a status that crack regions are formed on the glass by laser and a cutting edge is formed on the glass along the crack regions with the laser in a glass cutting method of another embodiment of the present invention; 
           [0020]      FIG. 4   a  is a schematic perspective diagram illustrating a laser apparatus for cutting glass according to a glass cutting method of the present invention; 
           [0021]      FIG. 4   b  is a schematic surface diagram illustrating the laser apparatus for cutting glass according to a glass cutting method of the present invention; 
           [0022]      FIG. 5  is a cross-sectional diagram illustrating the laser apparatus for cutting glass according to a glass cutting method of the present invention; and 
           [0023]      FIG. 6  is a cross-sectional diagram illustrating another laser apparatus for cutting glass according to a glass cutting method of the present invention. 
           [0024]      FIG. 7   a  is a perspective diagram illustrating glass for a flat panel display device of another embodiment of the present invention; 
           [0025]      FIG. 7   b  is a partial expanded diagram illustrating the glass of another embodiment of the present invention; 
           [0026]      FIG. 7   c  is a partial expanded diagram illustrating an outer peripheral surface of the glass of another embodiment of the present invention; 
           [0027]      FIG. 8  is an expanded perspective diagram illustrating glass for flat panel display device of another embodiment of the present invention; 
           [0028]      FIG. 9  is a perspective diagram illustrating a status that two sheets of glass according to the present invention overlap each other; 
           [0029]      FIG. 10  is a partial cross-sectional diagram illustrating one example of the plasma display panel using the glass according to the present invention; 
           [0030]      FIG. 11  is a partial cross-sectional diagram illustrating another example of the organic light emitting display panel using the glass according to the present invention; and 
           [0031]      FIG. 12  is a partial cross-sectional diagram illustrating another example of the liquid crystal display panel using the glass according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0032]    Referring to  FIG. 1 , a glass cutting method according to the present invention is illustrated by a flowchart. 
         [0033]    The glass cutting method according to the present invention includes forming a crack region S 1  and a full-through cutting S 2 . Additionally, either a curved surface or a chamfer is formed along the cutting edge S 3 . 
         [0034]    In forming the crack region S 1 , laser beams are output intermittently from a laser apparatus capable of moving in any X, Y and Z direction, so that crack regions with a constant size are formed at set pitches inside flat glass. For instance, as shown in  FIG. 2   a,  the glass  100  is loaded and the crack regions  104  are then preformed inside the glass  100  along the cutting edge by outputting laser beams intermittently. 
         [0035]    Here, it is desirable that the crack region  104  is formed in a size of approximately 1-20 μm. When the size of the crack region  104  is approximately 1 μm or less, the full-through laser cutting process may not be performed properly during the manufacturing process. Further, when the size thereof is approximately 2 μm or more, it overlaps with another neighboring crack region  104  so as to become oversized. 
         [0036]    Further, it is desirable that the crack region  104  is formed at a pitch of approximately 5-40 μm. When the pitch of the crack region  104  is approximately 5 μm or less, several crack regions  104  overlap each other so as to become oversized. On the other hand, when the pitch of the crack region  104  is approximately 40 μm or more, the full-through laser cutting process may not be performed properly during the manufacturing process. 
         [0037]    The crack region  104  is formed by focusing the laser beam on the approximate internal center of the glass  100 . However, actually, when focusing the laser beam within the range of 10-90% of the thickness of the glass  100 , the full-through laser cutting process is performed along the crack region without any problem. When the formation position of the crack region  104  is beyond the range of 10-90% of the thickness of the glass  100 , the full-through laser cutting process may not be performed properly during the manufacturing process. 
         [0038]    Further, the laser apparatus may be one apparatus selected from YAG laser apparatus and others, however, the present invention is not limited thereto. 
         [0039]    Additionally, it is desirable that the laser beam with a wavelength of approximately 300-400 nm is used when forming the crack region  104 . When the wavelength of the laser beam is approximately 300 nm or less, there is a great difference in the laser beam energy, so that the crack regions  104  may be formed excessively. The laser apparatus carries heavy workload. In addition, when the wavelength of the laser beam is approximately 400 nm or more, the laser beam energy may be too low to form the crack region  104  with a desirable size. 
         [0040]    Additionally, the thickness of the glass  100  may be approximately 0.5-5 mm, but not limited thereto. In other words, the glass may have either a thickness of 0.5 mm or less or a thickness of 5 mm or more. 
         [0041]    In the full-through cutting S 2 , laser beams are output continuously from the laser apparatus along the crack regions formed inside the glass, so that the full-through cutting of the glass is performed. Particularly, as shown in  FIG. 2   b,  laser beams are output continuously along the preformed crack regions, so that the glass is divided into pieces. In the drawing, reference numeral  103  denotes a cutting edge. 
         [0042]    Here, it is desirable that the laser beam with a wavelength of approximately 1000-1100 nm is used when performing the full-through cutting of the glass. When the wavelength of the laser beam is approximately 1000 nm or less, there is a great difference in the laser beam energy, so that the glass may be cut excessively. Additionally, when the wavelength of the laser beam is approximately 1100 nm or more, the laser beam energy may be too low to perform the full-through cutting process properly. 
         [0043]    Meanwhile, the full-through cutting step S 2  may be initiated after completion of the full-through cutting step S 2  over the whole glass. Particularly, as shown in  FIG. 2   a,  the crack regions  104  are preformed on the cutting region of the whole glass  100 . Then, as shown in  FIG. 2   b,  the full-through cutting of the glass is performed along the crack regions. The cutting edge  103  is accordingly formed on the glass  100 . 
         [0044]    However, according to the present invention, as shown in  FIG. 3 , the crack forming and full-through cutting S 1  and S 2  may be performed approximately at the same time. Particularly, as shown in  FIG. 3 , the crack regions  104  are formed then followed by performing the full-through cutting of the glass  100  so as to form the cutting edge  103 . The method illustrated in  FIG. 3  may be equipped with two laser apparatuses. 
         [0045]    Referring to  FIGS. 4   a  and  4   b,  a laser apparatus for glass cutting according to a glass cutting method of the present invention is illustrated by a schematic perspective diagram and a surface diagram. 
         [0046]    Referring to  FIG. 4   a,  the laser apparatus  700  is coupled to X directional guide rail  701  which is then coupled to the Y directional guide rail  702  again. The laser apparatus  700  may move in the X direction on the X directional guide rail  701  by a moving unit (not shown). Further, the X directional guide rail  701  may move in the Y direction on the Y directional guide rail  702  by a moving unit (not show). As a result thereof, the laser apparatus  700  can move in the X and Y directions. The laser apparatus  700  may move in the Z direction through an additional mechanical installation. Such structure is conventionally called XY table or XYZ table. 
         [0047]    Referring to  FIG. 4   b,  the laser apparatus  700  may further include a first reflective plate  703  positioned on the lower portion of the glass  100  so as to reflect the laser beam passing through the glass  100  toward the upper portion. Additionally, the laser apparatus  700 , as described below, may further include a second reflective plate  704  so as to reflect the laser beam reflected from the first reflective plate  703  toward the glass  100 . In the drawing, reference numeral  104  denotes the crack region  104  formed inside the glass  100  by a laser beam. 
         [0048]    Referring to  FIG. 5 , the laser apparatus for cutting glass according to a glass cutting method of the present invention is illustrated by a cross-sectional diagram. 
         [0049]    The first reflective plate  703  is positioned on the lower portion of the glass  100  so as to reflect the laser beam passing through the glass  100  toward the upper portion. Accordingly, the laser beam energy to be supplied to the glass is increased, so that the crack region  104  is formed more clearly during the crack region forming process and that the cutting process is performed more clearly during the full-through cutting process. 
         [0050]    The laser apparatus  700  includes a laser source  705 , a reflective mirror  706  reflecting the laser beam generated from the laser source  705  at a set angle, a collimating lens  707  collimating the laser beam that is reflected from the reflective mirror  706  in the downward direction, a focusing lens  708  adjusting the focus of the laser beam and an exterior case surrounding the laser source  705 , the reflective mirror  706 , the collimating lens  707  and the focusing lens  708 . 
         [0051]    As described above, according to the present invention, the second reflective plate  704  may be further attached to the lower end of the exterior case  709 . Additionally, the second reflective plate  704  may have a concave shape so as to concentrate the laser beam reflected from the first reflective plate  703  in one direction, but not limited thereto. 
         [0052]    The structured laser apparatus  700  performs either the crack region forming process or the full-through cutting process more completely due to the first and second reflective plates  703  and  704 . 
         [0053]    As described above, when forming the crack pint, the laser apparatus  700  emits the laser beam periodically. The laser beam is focused on the inside of the glass  100  by the focusing lens  708  that is coupled to the approximate center of the second reflective plate  704 . Accordingly, the laser beam is emitted intermittently so as to accumulate energy inside the glass  100  and consequently to expand the emission region of the laser beam. Strong stress is generated between the expanded and unexpanded regions, so that the crack region  104  with a constant size is formed on the emission region of the laser beam. 
         [0054]    Meanwhile, as described above, in the full-through cutting process, the laser apparatus  700  emits the laser beam continuously. The laser apparatus  700  moves in either the X direction or Y direction and simultaneously continuously emits the laser beam. Additionally, at this time, the laser beam passing through the glass  100  continues reciprocating motion between the first and second plates  703  and  704  positioned respectively on the lower portion of the glass  100  and the lower end of the laser apparatus thereby until it disappears. Accordingly, great amounts of energies accumulate in the glass  100  and the preformed crack regions  104  expand to the outer periphery. In other words, the expansion of the crack regions  104  results the full-through cutting of the glass  100 . 
         [0055]    Referring to  FIG. 6 , another laser apparatus for cutting glass according to a glass cutting method of the present invention and the peripheral structure thereof are illustrated by a cross-sectional diagram. 
         [0056]    Each of first and second laser apparatuses  700   a  and  700   b  may be positioned to the X directional guide rail  701 . Accordingly, the first laser apparatus  700   a  passes by on the glass  100  first forming the crack regions  104  with a constant size and pitch and. Then, the second laser apparatus  700   b  directly performs the full-through cutting process along the crack regions  104 . In the drawing, reference numeral  103  denotes a cutting edge formed by the second laser apparatus. 
         [0057]    The first and second laser apparatus  700   a  and  700   b  are positioned on the one X directional guide rail  701  and performs the crack region forming and full-through cutting processes approximately at the same time. Accordingly, the glass cutting process is achieved more rapidly and more accurately. 
         [0058]    Referring to  FIGS. 7   a  and  7   b,  the glass for flat panel display device according to one exemplary embodiment of the present invention is illustrated respectively by a perspective diagram and a partial expanded diagram. Referring to  FIG. 7   c,  an outer peripheral surface thereof is illustrated by a partial expanded diagram. Referring to  FIG. 8 , the glass for flat panel display device according to another exemplary embodiment of the present invention is illustrated by an expanded perspective diagram. 
         [0059]    Referring to  FIGS. 7   a  to  7   c,  the glass for flat panel display device  100  includes a first planar surface  101 , an approximately or completely second planar surface  102  opposite to the first surface  101 , a third planar surface  103  connecting the flat first and second surfaces  101  and  102 , and a plurality of crack regions  104  with a constant size and pitch formed along the third planar surface  103 . 
         [0060]    The third planar surface  103  may be formed into a rectangular-shaped belt strap along the edge of the first and second surfaces  101  and  102 . The four edges of each of the first and second surfaces  101  and  102  may include either a round (not shown) or a chamfer (not shown) so as to prevent edges from being damaged or broken. 
         [0061]    As shown in  FIG. 7   b,  the first and third planar surfaces  101  and  103  may form a right angle. Further, the second and third planar surfaces  102  and  103  may form a right angle. Each of the first and third planar surfaces  101  and  103  and the second and third planar surfaces  102  and  103  may form a right angle. 
         [0062]    Referring to  FIG. 8 , the glass for flat panel display device  200  may further include a curved surface  205  with a constant radius between first and third planar surfaces  201  and  203 . Additionally, another curved surface  205  with a constant radius may be also formed between the second and third planar surfaces  202  and  203 . Another curved surface  205  with a constant radius may be further formed respectively between the first and third planar surfaces  201  and  203  and the second and third planar surfaces  202  and  203  at the same time. Such curved surface  205  plays the role in preventing each border region of the first and third planar surfaces  201  and  203 , and the second and third planar surfaces  202  and  203  from being damaged or broken caused by contact with manufacturing facilities in the manufacturing process of the flat panel display device. 
         [0063]    Further, it is desirable that the crack region  104  (including the crack region  204  shown in  FIG. 8 ) is formed in a size of approximately 1-20 μm. When the size of the crack region  104  is approximately 1 μm or less, the full-through laser cutting process may not be performed properly during the manufacturing process. Further, when the size thereof is approximately 2 μm or more, it overlaps with another neighboring crack region  104  so as to become oversized. 
         [0064]    Further, it is desirable that the crack region  104  is formed at a pitch of approximately 5-40 μm. When the pitch of the crack region  104  is approximately 5 μm or less, several crack regions  104  overlap each other so as to become oversized. On the other hand, when the pitch of the crack region  104  is approximately 40 μm or more, the full-through laser cutting process may not be performed properly during the manufacturing process. 
         [0065]    Further, the crack region  104  may be formed along the approximate center line of the third planar surface  103 . However, actually, when the crack region  104  is formed within the range of approximately 10-90% of the thickness of the third planar surface  103  (distance between the first and second surfaces  101  and  102 ), the full-through laser cutting process is performed without any problem. On the other hand, when the formation position of the crack region is beyond the range of 10-90% of the thickness of the third planar surface  103  (distance between the first and second surfaces  101  and  102 ), the full-through laser cutting process may not be performed properly during the manufacturing process. 
         [0066]    The thickness (distance) between the first and second surfaces  101  and  102  of the glass  100  may be approximately 0.5-5 mm, however, the present invention is not limited thereto. In other words, the glass  100  may have either a thickness of 0.5 mm or less or a thickness of 5 mm or more according to the flat panel display device. 
         [0067]    Meanwhile, the glass  100  may be used in one panel selected from a plasma display panel (referring to  FIG. 11 ), an organic light-emitting display panel (referring to  FIG. 12 ), a liquid crystal display panel (referring to  FIG. 13 ), and the like, however, the present invention is not limited thereto. 
         [0068]      FIG. 9  is a perspective diagram illustrating a status that two sheets of glass according to the present invention overlap each other. 
         [0069]    Referring to  FIG. 9 , a flat panel display device  300  may be formed with two sheets of the glass  100  overlapping each other. Of course, a display unit, that is, all kinds of the organic materials, the inorganic materials or the semiconductor layers for the display may be formed between the glasses  100  which are overlapped. In addition, the display unit is completely sealed by the glasses  100 . As shown in the drawing the two sheets of the glass  100  have a rectangular shape. However, the present invention is not limited thereto and the glass  100  may have a regular square shape or the like. 
         [0070]    Referring to  FIG. 10 , a plasma display panel using the glass according to the present invention is illustrated by a partial cross-sectional diagram. Herein, the partial cross-sectional diagram shows the cross-section of other components except the glass. Particularly, the drawing shows the outer peripheral surface (lateral face) of the glass. 
         [0071]    The plasma display panel  400  includes a first substrate  401 , an address electrode  402  formed on the first substrate  401 , a first dielectric layer  403  covering the address electrode  402 , a barrier rib  404  formed on the first dielectric layer  403 , a phosphor layer  405  formed on the first dielectric layer  403  and the barrier rib  404 , a second substrate  406  formed on the barrier rib  404 , a display electrode  407  formed on the second substrate  406 , a second dielectric layer  408  covering the display electrode  407  and a protective layer  409 . 
         [0072]    Here, a plurality of crack regions  401   a  and  406   a  may be formed with a laser in order to be guided in the first substrate  401  and the second substrate  406 , respectively. Because the diameter, the pitch and the forming location of the crack regions  401   a  and  406   a  are already enough illustrated in the above, it omits. 
         [0073]    Referring to  FIG. 11 , an organic light-emitting display device panel using the glass according to the present invention is illustrated by a partial cross-sectional diagram. Herein, the partial cross-sectional diagram shows the cross-section of other components except the glass. Particularly, the drawing shows the outer peripheral surface (lateral face) of the glass. 
         [0074]    The organic light-emitting display device panel  500  includes a first substrate  501 , a buffer layer  502  formed on the first substrate  501 , a semiconductor layer  503  formed on the  15  buffer layer  502 , a gate oxide film  504  formed on the semiconductor layer  503 , a gate electrode  505  formed on the gate oxide film  504 , an interlayer insulating layer  506  covering the gate electrode  505 , a source and drain electrodes  507  formed on the interlayer insulating layer  506  and coupled to the semiconductor layer  503 , a protection layer  508  covering the source and drain electrodes  507 , an organic light-emitting layer  509  formed on the protection layer  508  and coupled to the source and drain electrodes  507 , and a second substrate  510  formed on the organic light-emitting layer  509 . Here, the protection layer  508  includes an inorganic layer  508   a  and a planarization layer  508   b.  Further, the organic light-emitting layer  509  includes an anode  509   a,  an organic light-emitting thin film  509   b  and a cathode  509   c  in which the combination of an electron and a positive hole injected respectively from the cathode  509   a  and the anode  509   c  results light emitting. In the drawing, reference numeral  511  denotes a film for pixel definition layer. 
         [0075]    Here, a plurality of crack regions  501   a  and  510   a  may be formed with a laser in order to be guided in the first substrate  501  and the second substrate  510 , respectively. Because the diameter, the pitch and the forming location of the crack regions  501   a  and  510   a  are already enough illustrated in the above, it omits. 
         [0076]    Referring to  FIG. 12 , a liquid crystal display panel using the glass according to the present invention is illustrated by a partial cross-sectional diagram. Herein, the partial cross-sectional diagram shows the cross-section of other components except the glass. Particularly, the drawing shows the outer peripheral surface (lateral face) of the glass. 
         [0077]    The liquid crystal display panel  600  includes a first substrate  601 , a buffer layer  602  formed on the first substrate  601 , a semiconductor layer  603  formed on the buffer layer  602 , a gate oxide film  604  covering the semiconductor layer  603 , a gate electrode  605  formed on the gate oxide film  604 , an interlayer insulating layer  606  covering the gate electrode  605 , a source and drain electrodes  607  formed on the interlayer insulating layer  606  and coupled to the semiconductor layer  603 , a first protection layer  608  covering the source and drain electrodes  607 , a liquid crystal  609  formed on the first protection layer  608 , a second substrate  610  formed on the liquid crystal  609 , a color filter  611  formed on the second substrate  610 , an opposite electrode  612  formed on the color filter  611 , and a second protection layer  613  covering the opposite electrode  612 . In the drawing, reference numeral  614  (not described) denotes a black matrix. 
         [0078]    Here, a plurality of crack regions  601   a  and  610   a  may be formed with a laser in order to be guided in the first substrate  601  and the second substrate  610 , respectively. Because the diameter, the pitch and the forming location of the crack regions  601   a  and  610   a  are already enough illustrated in the above, it omits. 
         [0079]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.