Abstract:
A cassette for a substrate is provided, which includes: a frame; and a plurality sets of supporting members defining slots layered in a vertical direction, wherein each set of supporting members comprises: a plurality of first support bars that extend in a first horizontal direction, nave ends fixed to the frame, and mount the substrate; and a support wire that is coupled with the first support bars and has ends fixed to the frame.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to and the benefit of Korean Patent Application No. 10-2003-0095417, filed on Dec. 23, 2003, which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     (a) Field of the Invention  
         [0003]     The present invention relates to a cassette for substrate.  
         [0004]     (b) Description of Related Art  
         [0005]     Generally, a semiconductor substrate used for a semiconductor device or a glass substrate for a flat panel display such as a liquid crystal display (LCD) and an organic light emitting display (OLED) is transferred by a transport system during the fabrication of the semiconductor device or the display panel.  
         [0006]     An LCD generally includes two panels made of glass substrates and a liquid crystal layer, while an OLED includes a signal panel made of glass substrates. The LCD displays images by applying voltages to field-generating electrodes disposed on the panels to generate electric fields, which determine the orientations of liquid crystal molecules in the liquid crystal layer. The OLED displays images by applying currents or voltages to light emitting diodes that emits light depending on the currents or voltages.  
         [0007]     A conventional substrate transport apparatus for LCDs transfers glass substrates to several process equipments using cassettes, stockers, and indexers. Several substrates are received in cassettes, and the cassettes containing the substrates are stocked in a stocker. The substrates are taken out of the cassette by a robot indexer and brought into process equipments.  
         [0008]     However, the conventional substrate transport apparatus may have several problems as the as the glass substrates becomes large, for example, larger than about 1,500 mm.  
         [0009]     First, the large substrates stored in the cassette are apt to get drooping due to its heavy weight. In addition, heavier substrates require larger and heavy supporting bars in the cassette and the large and heavy supporting bars are apt to get drooping and to be trembled. Moreover, heavier substrates also require larger robot arms of indexers large and thus the pitch of horizontal shelves of a cassette gets large to increase the cassette and the stocker. The large and heavy substrates may also cause problems in other devices such as a cassette crane, a cassette conveyor, and a lifer for handing the cassettes.  
       SUMMARY OF THE INVENTION  
       [0010]     A cassette for a substrate is provided, which includes: a frame; and a plurality sets of supporting members defining slots layered in a vertical direction, wherein each set of supporting members comprises: a plurality of first support bars that extend in a first horizontal direction, have ends fixed to the frame, and mount the substrate; and a support wire that is coupled with the first support bars and has ends fixed to the frame.  
         [0011]     The first support bars may be spaced apart from each other.  
         [0012]     The support wire may be coupled with bottoms of the first support bars.  
         [0013]     Each set of supporting members may further include a plurality of second support bars extending in a second horizontal direction intersecting the first horizontal direction, having ends fixed to the frame, and mounting the substrate.  
         [0014]     The first support bars may include buffers disposed at top, which may include polyetheretherketone (PEEK).  
         [0015]     The second support bars may have top surfaces having the same height as the buffer.  
         [0016]     The frame may include Al and stainless steel and the first supporting bars may include carbon fiber reinforced plastics.  
         [0017]     A cassette for a substrate is provided, which includes: a frame; and a plurality sets of supporting members defining slots layered in a vertical direction, wherein each set of supporting members comprises: a base having a horizontal plane; and a plurality of support columns that is disposed on the base and mount the substrate.  
         [0018]     The base may include a plurality of base bars having ends fixed at the frame or a base plate having edges fixed at the frame.  
         [0019]     The support columns may include polyetheretherketone (PEEK). 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     The present invention will become more apparent by describing embodiments thereof in detail with reference to the accompanying drawings in which:  
         [0021]      FIG. 1  is a plan view of a cassette according to an embodiment of the present invention;  
         [0022]      FIG. 2  is a sectional view of the cassette shown in  FIG. 2 ;  
         [0023]      FIG. 3  is an expanded sectional view of a portion A of the cassette shown in  FIG. 2 ;  
         [0024]      FIG. 4  is a plan view of a cassette according to an embodiment of the present invention;  
         [0025]      FIG. 5  is a sectional view of the cassette shown in  FIG. 4 ;  
         [0026]      FIG. 6  is an expanded sectional view of a portion B of the cassette shown in  FIG. 5 ; and  
         [0027]      FIG. 7  is a plan view of a cassette according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF EMBODIMENTS  
       [0028]     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, like numerals refer to like elements throughout.  
         [0029]     Then, cassettes for substrates will be described in detail with reference to accompanying drawings.  
         [0030]      FIG. 1  is a plan view of a cassette according to an embodiment of the present invention,  FIG. 2  is a sectional view of the cassette shown in  FIG. 2 , and  FIG. 3  is an expanded sectional view of a portion A of the cassette shown in  FIG. 2 .  
         [0031]     Referring to  FIGS. 1-3 , a cassette according to an embodiment of the present invention includes a cuboidal frame  210  and a plurality of slots layered in a vertical direction, each slot defined by a set of supporting members  220 ,  230  and  240  that mount a substrate  110 .  
         [0032]     The frame  210  includes three vertical walls and an entrance/exit for the substrate  110 , and a rear wall facing the entrance/exit includes a plurality of vertical bars  211 . The frame  210  is preferably made of Al and stainless steel such as SUS (Steel Use Stainless).  
         [0033]     A set of supporting members include a plurality of, for example, three long, main support bars  220  horizontally extending from the vertical wall bars  211  of the frame  210 , a support wire  240  connecting the main support bars  220 , and a plurality of short, auxiliary support bars  230  extending horizontally extending from the frame  210 .  
         [0034]     A substrate  110  is mounted on the main support bars  220  and the auxiliary support bars  230  by robot transporting arms (not shown). The robot arms carrying the substrate  110  enter the space between the main support members  230 , put down the substrate  110  on the main support members  230 , and return.  
         [0035]     The main support bars  220  are separated from each other and it is preferable that they extend parallel to one another. Each of the main supports  220  has a coupling member  222  at its bottom.  
         [0036]     The main support bars  220  are preferably made of CFRP (carbon fiber reinforced plastics). CFRP is a polymer complex used for exterior structure, which has tensile modulus higher than about 4.5 times that of Al and specific modulus about 3.3 time that of Al. In addition, fatigue limit of CFRP is maintained up to about 80% of it initial value, while that of Al is equal to only about 35% of its initial value.  
         [0037]     Each of the main support bars  220  includes a plurality of buffers  221  at its top and the buffers  221  absorb the impact during the mounting of the substrate  110 . The buffer  221  is preferably made of PEEK (polyetheretherketone) that is a specific durable thermoplastic resin having a continuous use temperature (CUT) equal to about 250° C.  
         [0038]     The support wire  240  is coupled with the main support bars  220  through the coupling members  222  and has ends fixed at the frame  210 . The tension of the support wire  240  is adjusted by drawing or releasing the ends of the support wire  240 . The support wire  240  prevents the main support bars  220  from being curved or trembling, when the main supports  220  mount the substrate  110 . It is preferable that the support wire  240  is made of steel and has a diameter equal to about 3-5 mm.  
         [0039]     It is preferable that the pitch of the support wires  240  (or the distance between adjacent support wires  240 ) is equal to about 75-95 mm and a gap between a support wire  240  and a buffer  221  adjacent thereto is about 50-70 mm such that an available space given to the transporting arms is about 80 mm.  
         [0040]     The auxiliary support bars  230  horizontally extend from side walls of the frame  210  and support side edge portions of the substrate  110 . The auxiliary support bars  230  preferably have top surfaces having the same height as the buffer  221  to maintain a mounted substrate  110  horizontal.  
         [0041]     The extension directions of the auxiliary support bars  230  may make a right angle or an oblique angle with those of the main support bars  220 .  
         [0042]     Next, a cassette according to another embodiment of the present invention will be described with reference to  FIGS. 4-6 .  
         [0043]      FIG. 4  is a plan view of a cassette according to an embodiment of the present invention,  FIG. 5  is a sectional view of the cassette shown in  FIG. 4 , and  FIG. 6  is an expanded sectional view of a portion B of the cassette shown in  FIG. 5 .  
         [0044]     Referring to  FIGS. 4-6 , a cassette according to this embodiment includes a cuboidal frame  210  and a plurality of slots layered in a vertical direction, each slot defined by a set of supporting members  250  and  260  that mount a substrate  110 .  
         [0045]     The frame  210  includes three vertical walls and an entrance/exit for the substrate  110 . The frame  210  is preferably made of Al and stainless steel such as SUS.  
         [0046]     A set of supporting members include a base plate  250  having edges fixed at the walls of the frame  210  and a plurality of support columns  260  standing on the base plate  250 . The support columns  260  are regularly arranged and preferably made of PEEK. The substrate  110  is mounted on the support columns  260 .  
         [0047]     Next, a cassette according to another embodiment of the present invention will be described with reference to  FIG. 7 .  
         [0048]      FIG. 7  is a plan view of a cassette according to an embodiment of the present invention.  
         [0049]     Referring to  FIG. 7 , a cassette according to this embodiment has a similar structure to that shown in  FIGS. 4-6 . That is, the cassette includes a cuboidal frame  210  and a plurality of slots layered in a vertical direction, each slot defined by a set of supporting members  260  and  270  that mount a substrate  110 .  
         [0050]     However, a set of supporting members include a plurality of horizontally extending base bars  270  having two opposite ends fixed at side walls of the frame  210  instead of a platelike base and a plurality of support columns  260  standing on the base bars  270 . The cassette shown in  FIG. 7  is lighter than that shown in  FIGS. 4-6 .  
         [0051]     The cassettes shown in  FIGS. 4-7  can easily store the substrate  110  in a flat state, and thus effectively prevents the substrate  110  from drooping and trembling.  
         [0052]     To summarize, the cassettes according to the embodiments of the present invention prevent the substrate from being drooping and trembling. In addition, the support wire reduces the increase of the pitch between the slots and the increase of the weight of the cassette, thereby enabling to simplify and optimize the structure of the cassette.  
         [0053]     While the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing from the spirit and scope of the present invention as set forth in the appended claims.