Patent Publication Number: US-2006016709-A1

Title: Cassettes for receiving glass substrates

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to cassettes, and more particularly, to cassettes for receiving glass substrates of liquid crystal displays (LCDs).  
      2. Discussion of the Related Art  
      Panels of display devices often comprise transparent substrates, which are becoming increasingly thinner and reducing the size, weight of products. Transparent substrates comprise glass, quartz, or organic transparent materials such as polycarbonate (PC), poly methyl methacrylate (PMMA). In a thin film transistor-liquid crystal displays (TFT-LCDs) manufacturing process, glass substrates of the panel or other plate-like objects are loaded and stored in a cassette, and can be moved or transported by mechanical arms.  
      As shown in  FIG. 1A , glass substrates S 1 ′ are stored in a cassette C. The cassette C comprises a frame  100 ′ and a plurality of cantilevers  101 ′ and  102 ′. The frame  100 ′ is rectangular. The cantilevers  101 ′ and  102 ′ are evenly disposed on inner walls  110 ′ and  120 ′ of the frame  100 ′. The frame  100 ′ is divided into a plurality of floors  105 . Each floor  105  has a height H p , which is a floor pitch or distance between floors. Each substrate S 1 ′ is supported by two cantilevers  101 ′ and  102 ′ at the same level.  
       FIG. 1B  is a front view of the conventional cassette C when a mechanical arm M is transferring a glass substrate S 1 ′ therein. The mechanical arm M comprises a first support portion  5 ′ and a second support portion  6 ′ with a predetermined distance W′ therebetween. When the mechanical arm M transports the substrate S 1 ′, the mechanical arm M moving into an assigned floor  105  of the cassette C, transfers the substrate S 1 ′ on the cantilever  101 ′ and  102 ′, thereby completing storage of the substrate S 1 ′. Conversely, when taking the substrate S 1 ′ out of the cassette C, the mechanical arm M moves into the cassette C directly under the substrate S 1 ′, and the support portions  5 ′ and  6 ′ thereof simultaneously support the substrate S 1 ′ and move it out of the cassette C.  
      The substrate S 1 ′ is supported by the cantilevers  101 ′ and  102 ′ on the inner walls  110 ′ and  120 ′ of the cassette C; however, due to the self-weight of the substrate S 1 ′, a central portion thereof is slightly deformed downward.  
      Furthermore, the glass substrates are categorized into various generations with different dimensions such as the 2.5-generation (370 mm by 470 mm), the 3 rd -generation (550 mm by 650 mm), the 3.5-generation (660 mm by 720 mm), the 4 th -generation (680 mm by 880 mm), the 5 th -generation (1100 mm by 1250 m). The trend is toward even larger substrate sizes, such as 6 th - or 7 th -generation substrates (about 1900 mm by 2200 mm). The thickness thereof is reduced from 0.7 mm to the current 0.4 mm. That is, the substrates are larger and thinner, and thus, the deflection ratio of the central portion of the substrates is increased.  
      When the mechanical arm M is loading the large and thin substrate S 1 ′, each end E 1  of the substrate S 1 ′ is naturally deflected downward by self-weight, as shown in  FIG. 1C . H c  is the deflected length of the end E 1 . In the conventional cassette C, during transportation, if the misalignment of the mechanical arm M is severe enough, it may cause one end E 1  of the substrate S 1 ′ to strike the cantilevers  101 ′ and  102 ′ of the cassette C and break inside the cassette C. Thus, yield rate is reduced, wasting materials and increasing process time.  
      To safely transport the substrates S 1 ′ from the cassette C, the distance H p  must be greater than H c . The distance H p  of each floor  105  must be increased to avoid contact between the ends E 1 , E 2  of the substrate S 1 ′ and the cassette C. Thus, the large substrates require a larger sized cassette. Furthermore, due to space constraints, the cassette must be appropriately sized for convenience during storage and removal of the substrates, and thus, the storage volume of the cassette C is reduced accordingly. Hence, reduction of defects in the glass substrate when transferred from one position to another is critical.  
     SUMMARY OF THE INVENTION  
      Accordingly, an object of the present invention is improving cassette and to safely transport the objects not struck the cassette during transportation.  
      Another object of the present invention to change the cantilevers shaped of the cassette, which to reduce the total height and weight of the cassette.  
      Further another object of present invention to increased the floor amount, which to increase the stored amount of objects.  
      For the purpose of the present invention, cassettes are provided. An exemplary embodiment of a cassette for receiving an object comprises a sidewall and a cantilever. The sidewall is perpendicular to a horizon. The cantilever for supporting the object comprises a fixed-end attached to the sidewall, thereby forming an angle with the horizon, and the angle in the range of about 1° to 10°.  
      The cantilever further comprises a front-end, and a lower portion of the front-end comprises a notch. The thickness of the cantilever decreases along the front-end.  
      Additionally, the lower portion of the front-end is substantially step-shaped. The cassette further comprises a pad, and the pad is disposed on the front-end. The pad comprises an elastic polymer such as rubber, soft Polypropylene, or like.  
      Further provided is a cassette for receiving an object comprising a sidewall and a cantilever. The sidewall is perpendicular to a horizon. The cantilever for supporting the object comprises a fixed-end attached to the sidewall and a front-end having a thickness less than that of the fixed-end. The front-end comprises a notch. The thickness of the cantilever decreases from the fixed-end to the front-end. Moreover, the front-end is substantially step-shaped. The cassette further comprises a pad, disposed on the front-end. The pad comprises an elastic polymer such as rubber, soft Polypropylene, or like.  
      Some embodiments of a cassette for receiving an object comprise a first sidewall, a first cantilever, a second sidewall, and a second cantilever. The first sidewall is perpendicular to a horizon. The first cantilever is disposed on the first sidewall. The second sidewall opposes and parallel to the first sidewall. The second cantilever is disposed on the second sidewall. The first cantilever and the horizon form a first angle, and the second cantilever and the horizon form a second angle. The first angle and the second angle are substantially identical. 
    
    
     DESCRIPTION OF THE DRAWINGS  
      Cassettes for receiving glass substrates can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein:  
       FIG. 1A  is a schematic internal view of a conventional cassette;  
       FIG. 1B  is a front view of the conventional cassette with a mechanical arm;  
       FIG. 1C  is a local enlarged view of the conventional cassette;  
       FIG. 2A  is a front view of an embodiment of a cassette;  
       FIG. 2B  is a front view of the cassette with a mechanical arm of the  FIG. 2A ;  
       FIG. 2C  is a local enlarged view of a first cantilever of the cassette of the  FIG. 2A ;  
       FIG. 3A  is a front view of an embodiment of a cassette;  
       FIG. 3B  is a front view of an embodiment of the cassette with a mechanical arm of the  FIG. 3A ;  
       FIG. 3C  is a local enlarged view of a first cantilever of the cassette of the  FIG. 3A ;  
       FIG. 3D  is a local enlarged view of a variation of the first cantilever of the cassette of the  FIG. 3A ;  
       FIG. 4A  is a front view of an embodiment of a cassette;  
       FIG. 4B  is a front view of an embodiment of the cassette of the  FIG. 4A  with a mechanical arm;  
       FIG. 4C  is a local enlarged view of a first cantilever of the cassette of the  FIG. 4A ;  
       FIG. 4D  is a local enlarged view of a variation of the first cantilever of the cassette of the  FIG. 4A . 
    
    
     DETAILED DESCRIPTION  
      Cassettes for receiving glass substrates are provided. An exemplary embodiment of a cassette for receiving glass substrates is applicable to a TFT-LCD panel manufacturing process when transporting a plurality of objects such as glass substrates or other plate-shaped objects in a cassette by a mechanical arm M. The cassette is used to load and store the objects S 1 . The mechanical arm M can enter the cassette and move horizontally upward or downward to transfer the object S 1 .  
       FIG. 2A  is a front view of an embodiment of a cassette C 1 . The cassette C 1  comprises a frame  100 , a first sidewall  110 , a second sidewall  120 , a first cantilever  11 , and a second cantilever  12 . Note that the quantity of cantilevers is not limited to two, and the cassette C 1  can comprise a plurality of cantilevers. In some embodiments, the first cantilever  11  and the second cantilever  12  are provided.  
      The first sidewall  110  and the second sidewall  120  are perpendicular to a horizon h. The second sidewall  120  is opposing and parallel to the first sidewall  110 . The first cantilever  11  comprises a first fixed-end  11   a  and a first front-end  11   b . The first fixed-end  11   a  is attached to the first sidewall  110 . The second cantilever  12  comprises a second fixed-end  12   a  and a second front-end  12   b . The second fixed-end  12   a  is attached to the second sidewall  120 . The object S 1  is supported by the front-ends  11   b  and  12   b  of the cassette having a plurality of pads  160  disposed thereon, preventing direct contact between the object S 1  and the cantilevers  11  and  12 .  
      The first cantilever  11  and the horizon h form a first angle θ 1 . The second cantilever  12  and the horizon h form a second angle θ 2 . The first angle θ 1  is substantially identical the second angle θ 2 . The first and second angles θ 1 , θ 2  in the range of about 1° to 10°, preferably range of about 1° to 4°, varying with the length, thickness, weight and materials of the object S 1 .  
       FIG. 2B  is a front view of the cassette C 1  with a mechanical arm M.  FIG. 2C  is a local enlarged view of a first cantilever  11  of the cassette C 1 . The mechanical arm M comprises two support portions  5  and  6  located inside a floor  150  of the cassette C, supporting one of the objects S 1 . When supported by the mechanical arm M, two ends of the object S 1  is deformed downward. The first angle θ 1  of the first cantilever  11  is substantially identical an inclined angle θ 1 ′ of the end section E of the object S 1 . Thus, the first cantilever  11  is substantially parallel to the section E.  
      Since the shapes of the cantilevers and the end sections of the objects are similar and parallel, the end section E does not strike the cantilevers when the mechanical arm M loading the substrate moves up or down therebetween, preventing breakage of the substrate.  
      Furthermore, as shown in  FIG. 2C , the first cantilever  11  is inclined upward, an additional height D 1  is provided for the floor  105  near the front-end  11   b , and thus, distance between floors of the cassette can be increased. The additional height D 1  provides sufficient clearance, preventing contact between the object S 1  and the cantilevers  11  and  12  during transportation. Since the distance between the floors  105  in the cassette C 1  can be reduced, the overall size of the cassette C 1  can be reduced, providing a more compact sized cassette. Under other circumstances, when a larger storage capacity is required, since the distance between the floors can be reduced, the overall size of the cassette C 1  can remain the same but more floors can be added for storing more objects. Hence, the capacity of the cassette C 1  can be increased without increasing overall size thereof.  
       FIGS. 3A, 3B , and  3 C are schematic views of an embodiment of the cassette C 2 . The cassette C 2  comprises a frame  200 , a first sidewall  210 , a second sidewall  220 , a first cantilever  21 , and a second cantilever  22 . Note that explanations of elements and connecting structures common to the previously described embodiments are omitted.  
      As shown in  FIG. 3A-3C , the difference is that the shapes of the front-ends  21   b  and  22   b  of the first cantilever  21  and the second cantilever  22  are different. The thickness of the front-ends  21   b  and  22   b  is less than that of the fixed-ends  21   a  and  22   a . That is, the first front-end  21   b  of the first cantilever  21  comprises a notch  25 , and the second front-end  22   b  of the second cantilever  22  comprises a notch  26 . The cantilevers  21  and  22  are substantially step-shaped.  
      Moreover, the first and the second cantilevers  21  and  22  remain horizontal, unlike the inclined cantilevers in some embodiments. Similarly, the pads  260  are disposed on the first and second cantilevers  21 ,  22  to prevent direct contact of the object S 2 .  
       FIG. 3B  is a front view of the cassette C 2  with a mechanical arm M.  FIG. 3C  is a local enlarged view of a first cantilever of the cassette C 2 . As shown in  FIGS. 3B and 3C , the mechanical arm M is located on a floor  250  of the cassette C 2  and loads one of the objects S 2  by the support portions  5  and  6  thereof. When the mechanical arm M is loading the object S 1 , two end sections E thereof are slightly deflected downward. Since the first front-end  21   b  of the first cantilever  21  comprises a notch having a height D 2 , which varies with inclined angle of the end sections E of the object S 2 , the notch  25  provides an additional transport space for the mechanical arm M such that contact between the end section E and the first cantilever can be prevented. Thus, the floor pitch H 2  of the cassette C 2  can be reduced accordingly. The overall size of the cassette C 2  can be reduced, providing a more compact sized cassette. In some embodiments, when larger storage capacity of the cassette C 2  is required, since distance between the floors can be reduced, the overall size of the cassette C 2  can remain the same and more of the floors can be added for storing more objects. Hence, the capacity of the cassette C 2  can be increased without increasing overall size thereof.  
      The cassette further has a variation. As shown in  FIG. 3D , from which common elements share the same symbols and description thereof is omitted. The first cantilever  21 ′ is provided as an example. The first cantilever  21 ′ and the horizon h form a third angle θ 3 , and the third angle in the range of about 1° to 10°, and the third angle θ 3  preferably range of about 1° to 4°.  
      Since the first cantilever  21 ′ and the second cantilever  21 ′ are symmetrically arranged, the figure of the second cantilever  22 ′ is omitted. Although not shown, the second cantilever  22 ′ has substantially identical angle θ 3  as that of the first cantilever  21 ′. The third angle θ 3  varies with the length, thickness, weight and materials of the object S 2 .  
      Since the cantilever is inclined at the third angle θ 3 , an additional height D 3  is provided to increase transport space in the cassette. Thus, each floor pitch H 2 ′ can be reduced accordingly. In this variation, the floor pitch H 2 ′ is less than the floor pitch H 2 . Since floor pitch H 2  or H 2 ′ can be reduced, capacity of the cassette C 2  can be increased.  
       FIGS. 4A, 4B , and  4 C are schematic views of the cassette C 3 . The cassette C 3  comprises a frame  300 , a first sidewall  310 , a second sidewall  320 , a first cantilever  31 , and a second cantilever  32 .  
      The difference is the shape of the front-ends  31   b  and  32   b  of the first and second cantilevers  31  and  32 . The thickness of the front-ends  31   b  and  32   b  of the first and second cantilevers  31  and  32  is less than that of the fixed-ends  31   a  and  32   a . The thickness of the cantilevers  31  and  32  decreases from the fixed-ends  31   a  and  32   a  along the front-ends  31   b  and  32   b.    
      As shown in  FIGS. 4B and 4C , a section P 1  of the first cantilever  31  comprises a slope  33 , forming a fourth angle θ 4  with the horizon h. The slope  33  of the section P 1  of the first cantilever  31  is substantially parallel to the end section E of the object S 3  with similar shapes. Likewise, the second cantilever  32  has a slope forming a fifth angle θ 5  with the horizon h. The additional distance D 4  provides extra transport space. Thus, contact between the end section E of the objects S 3  and the cantilevers  31  and  32  can be prevented when the mechanical arm M loads the object.  
      Note that, in some embodiments, the first and second cantilevers  31  and  32  remain horizontal. That is, the first and second cantilevers  31  and  32  are perpendicular to the first and second sidewalls  310  and  320 . Moreover, elastic pads  360  can be disposed on the first and second cantilevers  31 ,  32 , preventing direct contact between the object S 3  and the cantilevers  31 ,  32 .  
      Thus, since the floor pitch H 3  of the cassette C 3  can be reduced accordingly, the overall size of the cassette C 3  can be reduced, potentially providing a more compact sized cassette. In some embodiments, when larger storage capacity of the cassette C 3  is required, since distance between the floors can be reduced, the overall size of the cassette C 3  can remain the same, and more of the floors can be added for storing more objects. Hence, the capacity of the cassette C 3  can be increased without increasing overall size thereof.  
      The cassette C 3  has a variation. As shown in  FIG. 4D , from which common elements share the same symbols and description thereof is omitted. The first cantilever  31 ′ is provided as an example. The first cantilever  31 ′ and the horizon h form a sixth angle θ 6 , the sixth angle in the range of about 1° to 10°, and the sixth angle θ 6  preferably range of about 1° to 4°. Since the first cantilever  31 ′ and the second cantilever  31 ′ are symmetrically arranged, the figure of the second cantilever  32 ′ is omitted. Although not shown, the second cantilever  32 ′ has the same sixth angle θ 6  as that of the first cantilever  31 ′. The sixth angle θ 6  varies with the length, thickness, weight and materials of the object S 3 .  
      Since the cantilever  31 ′ is inclined at the sixth angle θ 6 , an additional height D 4  is provided to increase transport space in the cassette. Thus, each floor pitch H 3 ′ can be reduced accordingly. In this variation, the floor pitch H 3 ′ is less than the floor pitch H 3  of the cassette C 3 . Since floor pitch H 3  or H 3 ′ can be reduced, capacity of the cassette C 3  can be increased.  
      Cassettes for receiving glass substrates may prevent contact between the objects and the cantilevers during transport and provide a compact cassette with lighter weight and reduced height.  
      While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.