Abstract:
A glass substrate cassette includes a bottom structure, a top structure, and a pair of side supports affixed to space the bottom structure and the top structure for forming an accommodation space in between. A plurality of support plates are horizontally affixed between the side supports. Each of the support plates is shaped as a corrugated plate structure for supporting thereon a glass substrate. The corrugated support plate has recess portions for allowing a delivering device to load and/or unload the glass substrates.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     (1) Field of the Invention  
         [0002]     The invention relates to a glass substrate cassette, and more particularly to a cassette for supporting large-size glass substrates.  
         [0003]     (2) Description of the Related Art  
         [0004]     With prosperous growth in Thin Film Transistor Liquid Crystal Display (TFT LCD) technology, the TFT LCD has gradually displaced the cathode ray tube (CRT) display in the market and become the mainstream of the display technology. The TFT LCD having various advantages such as compactness in size, low power consumption and low radiation is widely applied to electronic products such as personal digital assistants (PDAs), mobile phones, digital video cameras, digital cameras, notebook computers, and televisions.  
         [0005]     One of key components in a typical TFT LCD is a glass substrate. The glass substrate has a large amount of thin film transistors formed thereon. These transistors serve as switch devices for controlling pixel brightness of the display, in which the pixel is the basic element in the TFT LCD for forming a desired image on the liquid crystal display. In manufacturing the TFT LCDs, a cassette is usually used to transport and/or buffer the fragile glass substrates.  
         [0006]     Referring to  FIG. 1A , a conventional cassette  1  for stacking a plurality of glass substrates  4  is illustrated. As shown, the cassette  1  is formed as a hollow container  10  with a fully-open transporting. gate  11  in a front side. A plurality of pairing support pins  12  are affixed to opposing lateral sides of the transporting gate  11 . A socket  13  is therefore formed between adjacent support pins  12 . The glass substrates  4  can be stored into the respective sockets  13  and thus supported by the underneath support pins  12 . In this design, a delivery device  5  can be used to load/unload the substrates  4  with respect to the sockets  13 .  
         [0007]     For the sixth-generation TFT LCDs, a conventional cassette  1  may store broad and thin glass substrates that have a dimension of about 1500 mm×1850 mm. When the glass substrate  4  is. supported by the support pins  12  as shown in  FIG. 1B , the substrate  4  will deflect downward to form a concave shape due to the gravity. It is apparent that an abrupt contact between the delivery device  5  and the brittle glass substrate  4  during the loading/unloading process may break the glass substrate  4  and cause irreversible damage to the substrate  4 .  
         [0008]     Referring to  FIG. 2A , another conventional cassette  2  having a plurality of support wires  21  connecting two opposing lateral sides of the cassette  2  is shown. The socket  22  may be formed between every two adjacent support wires  21 . The glass substrate  4  is stored in the socket  22  and supported by the support wires  21 . However, the glass substrate  4  still deflects concavely due to its own weight and the flexibility of the support wire  21 .  
         [0009]     To overcome the problem of deflection of the substrate  4  in the cassette, transport rollers  6  can be introduced into the. cassette  4  for bearing the glass substrates  4 , as shown in  FIG. 2B . The transport rollers  6  may approach the glass substrate  4  from the bottom of the cassette  2  to lift the glass substrate  4  and unload the glass substrate  4  from the cassette  2 , as shown in  FIG. 2B .  
         [0010]     Generally, the substrates  4  are unloaded from the bottom of the cassette  2  to the top. On the other hand, the loading of the substrates  4  into the cassette  2  needs to follow a top-to-bottom order. It is clear that such design of the cassette  2  are unable to load/unload the substrates  4  in an arbitrary order.  
         [0011]     Referring to  FIG. 3 , it shows a third conventional cassette  3 . As compared to the above designs, the cassette  3  has parallel back support rods  33  affixed to the back side  32  of the cassette  3 . The back support rod  33  is a cantilever extending toward the transporting gate  34  to support the glass substrate. However, the cantilever back support rod  33  also deflects and thus the problem associated with concave substrates in the cassette  3  still remains.  
         [0012]     The disadvantages mentioned above are getting worse, especially when the glass substrate is broad and thin. In particular, with the brittle glass substrate stored in the cassette as described above, even a small impact or a low-energy vibration with a frequency close to the nature resonance frequency of the substrate may easily break the substrate.  
       SUMMARY OF THE INVENTION  
       [0013]     Accordingly, it is an object of the present invention to provide a cassette for carrying a glass substrate without a substantial midway curve-in deflection in the substrate.  
         [0014]     It is another object of the present invention to provide a cassette for carrying a glass substrate without inducing a significant surface stress to damage the substrate.  
         [0015]     It is still another object of the present invention to provide a cassette for carrying a large scale glass substrate without increasing the safety height of each socket.  
         [0016]     It is still another object of the present invention to provide a cassette for carrying a large scale glass substrate that can protect the substrate from possible resonance damage.  
         [0017]     According to the present invention, the cassette includes a bottom structure, a top structure, a pair of side supports facing each other and affixed to the bottom structure and the top structure, and a plurality of support plates horizontally affixed to the pair of side supports. Adjacent support plates are separated in a predetermined interval. Each of the support plates is formed as a corrugated structure having recess portions. A delivery device, such as a robot arm, is inserted into the recess portions for loading or unloading a glass substrate supported on the support plate.  
         [0018]     Preferably, a transport gate for allowing the substrate to enter and/or leave the cassette is located in the front of the cassette. The delivery device can pass through the transport gate and insert into the recess portions of a selected support plate for loading or unloading a glass substrate upon the support plate. Further, it is preferable that a rear support can be affixed to the bottom structure and the top structure to prevent the glass substrate from slipping out during its transportation.  
         [0019]     It is preferable that the support plate can be made of a thin plate material, such as an aluminum plate, a steel plate, a titanium plate, a reinforced fiberglass plate, and a reinforced carbon fiber. The support plate and the inner surface of the pair of the side supports may be connected by screw bolts. According the theory of shells, the corrugated support plate of the present invention can sustain a heavier load than a simple plane plate such that the deflection of the support plate can be substantially reduced. Furthermore, the surface stress on the glass substrate due to the deflection can also be eliminated and so the damage of the components of the glass substrate can be avoided.  
         [0020]     It is preferable that the corrugated support plate ensures the supporting capacity of the cassette, because no additional space for digesting the midway deflection factor is required between the adjacent support plates. In addition, the number and the size of the recess portions in the support plate is determined by considering fitting of the delivery device for loading or unloading.  
         [0021]     It is preferable for the support plate to have a plurality of through holes for draining during the process of rinse. The weight of the cassette can also be reduced for the existence of the through holes. Also, the arrangement of the through holes can be used to adjust the natural resonance frequency of the cassette.  
         [0022]     It is preferable that the bottom structure, the top structure, the side supports, and the rear support can be formed as plates or frames. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The present invention will now be specified with reference to its preferred embodiment illustrated in the drawings, in which:  
         [0024]      FIG. 1A  is a schematic perspective diagram of a first conventional cassette and a separate glass substrate;  
         [0025]      FIG. 1B  is a schematic front view of the cassette of  FIG. 1A , in which a plurality of the glass substrates has been found in respective sockets of the cassette;  
         [0026]      FIG. 2A  is a schematic front view of another conventional cassette having the glass substrates stored in respective sockets;  
         [0027]      FIG. 2B  is a schematic diagram showing a glass substrate unloaded by a delivery device for the cassette of  FIG. 2A , in which the up-and-down movable delivery device is equipped to a bottom of the cassette;  
         [0028]      FIG. 3  is a schematic cross-sectional side view of a third conventional cassette;  
         [0029]      FIG. 4  is a schematic perspective view of a preferred cassette in accordance with the present invention, in which a glass substrate is separately shown;  
         [0030]      FIG. 5  is a schematic diagram showing a preferred screw connection between a support plate and an inner surface of a side surface of the cassette in accordance with the present invention;  
         [0031]      FIG. 6  is a schematic perspective diagram of a preferred support plate of the present invention; and  
         [0032]      FIG. 7  is a schematic perspective view of another cassette in accordance with the present invention, also in which the glass substrate is separately shown. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     Referring to  FIG. 4 , there is shown a preferred cassette  7  of the present invention. The cassette  7  includes a bottom structure  71 , a top structure  72 , a pair of side supports  73 , a rear support  74 , and a plurality of support plates  75 . The bottom structure  71 , the top structure  72 , and the pair of side supports  73  are connected to form a cubic frame as shown.  
         [0034]     In  FIG. 4 , the side supports  73  face each other and are affixed at both ends of each side support  73  to the bottom structure  71  and the top structure  72 . The rear support  74  located to a rear side of the cassette  7  that connects the sides locating the side plates  73  is also affixed to the bottom structure  71  and the top structure  72 . The cubic-shaped cassette  7  is thus substantially formed as a hollow container with a transport gate  76  open in a front side of the cassette  7  opposite to the rear side where the rear support  74  locates.  
         [0035]     The support plates  75  inside the cubic cassette  7  are horizontally and parallel affixed between the pair of side supports  73 , also located between the bottom structure  71  and the top structure  72 . Every two adjacent support plates  75  are separated by a predetermined interval. The support plate  75  is formed as a corrugated structure  77  having recess portions  78  (two recess portions  78  shown in this embodiment). Preferably, the corrugated structure  77  has a shape of a square wave plate commercially available. The orientation of the recess portions  78  of the support plate  75  is preferably arranged to communicate in space with the transport gate  76  so as to allow a delivery device  5 , such as a robot arm, to enter for loading or unloading a glass substrate  4  supported on the support plate  75 . In one embodiment of the present invention, the number and the dimension of the recess portions  78  may be determined by the configuration of the delivery device  5 . For example, in  FIG. 4 , at least two recess portions  78  are required for the support plate  75  to meet the two-arm fork-shaped delivery device  5 .  
         [0036]     In one embodiment of the present invention, the support plate  75  may be a thin plate structure made of aluminum, steel, titanium, reinforced fiberglass, or reinforce carbon fiber. As shown in  FIG. 5 , a flange  79  may be formed at the edge of the support plate  75  for providing a screw connection with the side support  73  by screw bolts  80  or the like fastening means, for example.  
         [0037]     Referring to  FIG. 6 , there is shown a preferred support plate  75  of the present invention. The support plate  75  has a plurality of through holes  81  to facilitate draining during a rinse operation. Also, the dynamic performance of the cassette  7  may be adjusted by the locations and number of the through holes  81  on the support plates  75 . It is well known in the vibration theory that the natural resonance frequency of the support plate  75  as well as that of the cassette  7  may be shifted by the arrangement of the through holes  81 . Upon an appropriate arrangement of the through holes  81  on the support plates  75 , the glass substrate  4  sustained on the support plate  75  may be away from possible resonance damage resulted from operations of the neighboring equipments.  
         [0038]     In one embodiment of the present invention, the support plate  75  may be designed as a thin plate structure so as to reduce the weight but to increase the supporting capacity of the cassette  7 . In the application of thin shells or plates, the thin corrugated plate structure has the merit of light weight, high supporting strength, and large span.  
         [0039]     Referring to  FIG. 7 , there is shown another preferred embodiment of the cassette  7  according to the present invention. The elements are substantially the same as those of the previous preferred embodiments described above. However, in this embodiment, the bottom structure  71 , the top structure  72 , the side supports  73 , and the rear support  74  are all formed as plate structures, but not the frame structures in the foregoing embodiment of  FIG. 4 . In other words, as shown in  FIG. 7 , the bottom structure  71 , the top structure  72 , the side supports  73 , and the rear support  74  are integrated to form as a container.  
         [0040]     In one embodiment of the present invention, the recess portions  78  of the support plate  75 , either in  FIG. 4  or in  FIG. 7 , are formed in a parallel pattern.  
         [0041]     As compared to the conventional cassettes, the cassette according to the present invention has at least the following advantages: 
        a. The supporting capacity of the cassette of the invention may be bigger than that of the conventional cassette. Especially when the cassette is used to store large scale glass substrates, the degree of deflection of the glass substrate upon the corrugated support plate is substantially reduced. Also, the surface stress of the glass substrate can be reduced to a degree that the possible damage of the components of the glass substrate from the surface stress no longer occurs.     b. The bending strength of the support plate increases so that the interval between the adjacent support plates can be narrowed and thus the volume of the cassette can be reduced.     c. The arrangement of the through holes on the support plate can be utilized to adjust the weight and dynamic performance of the cassette.        
 
         [0045]     While the preferred embodiments of the present invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the present invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the present invention.