Abstract:
A clean stocker includes a storage rack storing an article, a load port holding a case and including a loading and unloading space to load and unload the article to and from the held case, a transferring apparatus including a holding space to hold the article and transfer the article between the holding space and the storage rack and between the holding space and the case held in the loading and unloading space, the holding space being kept clean, and a first shield closing the holding space and traveling together with the transferring apparatus.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to automated warehouses and, in particular, to an automated warehouse which stores articles in a clean space. 
     2. Description of the Related Art 
     Reticles have been used for manufacturing electronic components, and are stored in a clean stocker placed in a clean room (See Japanese Unexamined Patent Application Publication No. 2008-30914, for example). In the clean stocker, the reticles are taken out of pods for storage, and the environment inside the clean stocker chassis needs to be kept from volatile impurities. 
     A clean stocker disclosed in Japanese Unexamined Patent Application Publication No. 2008-30914 is equipped with a clean gas supply unit, placed in the upper part of the chassis of the clean stocker, to supply clean gas in order to prevent the volatile impurities from entering the chassis. 
     The above conventional structure, however, requires the clean gas to be supplied to spaces for holding and transporting reticles taken out of pods; specifically, all the spaces inside a pod opener, inside a rotation rack, and between the pod opener and the rotation rack (transportation route for the reticles). 
     Here, a chemical filter for the clean gas supply unit is a very expensive and expendable, and the life of the chemical filter decreases with an increasing amount of airflow. In other words, in the case where the clean gas is to be supplied to all the above spaces, the chemical filter will have to be replaced in a short period of time and the resulting expenses for the storage will increase. The expenses will further increase in the case where the environment inside the chassis is to be kept from moisture as well as the volatile impurities (hereinafter referred to as “clean space”). 
     SUMMARY OF THE INVENTION 
     In view of the above problems, preferred embodiments of the present invention provide an automated warehouse which is capable of efficiently storing articles in a clean space. 
     An automated warehouse according to a preferred embodiment of the present invention places an article in a case, and brings in and takes out the article. Specifically, the automated warehouse includes a storage rack which stores articles including the article; a load port which holds the case and includes a loading and unloading space to load and unload the article to and from the held case; a transferring apparatus which includes a holding space to hold the article and transfers the article between the holding space and the storage rack and between the holding space and the case held in the loading and unloading space, the holding space being kept clean; and a first shield which closes the holding space and travels together with the transferring apparatus. 
     The above structure allows the holding space alone to be kept clean instead of the entire transportation route of articles. Hence, the space to be cleaned is much smaller, which contributes to a decrease in storage expenses and efficient storage of articles. 
     It is noted that the language “closed” in the description of preferred embodiments of the present invention does not necessarily mean sealing a space as far as impurities are kept from entering the space. In the above example, the first shield may seal the opening for the holding space to keep impurities from entering the holding space. Alternatively, in order to keep impurities from entering the holding space, the first shield may be arranged so that there is a narrow clearance between the first shield and the opening for the holding space in order to let the clean gas in the holding space always escape via the clearance. 
     According to a preferred embodiment of the present invention, the load port may travel together with the transferring apparatus so that the holding space of the transferring apparatus and the loading and unloading space are connected with each other. The first shield may close to keep clean the loading and unloading space and the holding space connected with each other. 
     The above features allow the article taken out of a case at the load port to be transported to the storage rack without moving the article out of a clean space. Hence, the space to be cleaned is smaller, and contamination of the article is effectively prevented. 
     According to another preferred embodiment of the present invention, the first shield may include a cylinder to contain a rotatable transferring apparatus; a first opening arranged on a side of the cylinder to face the load port; and a second opening arranged on a side of the cylinder to face the storage rack. The transferring apparatus may: rotate to a position where an opening for the holding space faces the first opening, and transfer the article between the holding space and the load port; rotate to a position where the opening for the holding space faces the second opening, and transfer the article between the holding space and the storage rack; and rotate to a position where the opening for the holding space faces an inner sidewall of the cylinder, and travel together with the first shield with the holding space closed. 
     According to the above features, the transferring apparatus may rotate inside the first shield so that the opening for the holding space is exposed only when the apparatus transfers the article and closed when apparatus travels. Hence, the space to be cleaned is smaller, and contamination of the article is effectively prevented. 
     Moreover, the transferring apparatus may further be capable of vertically traveling inside the cylinder, and prior to the rotation inside the cylinder, the transferring apparatus may ascend or descend to a position where the opening for the holding space does not face either the first opening or the second opening. Such a feature prevents the opening from being exposed while the transferring apparatus is rotating. 
     Furthermore, the automated warehouse may include a second shield which is attached to an outer sidewall of the cylinder, travels together with the transferring apparatus and the first shield, and closes a loading and unloading opening on the storage rack to transfer the article when arriving at a position to face the storage rack. The second shield may include a connecting hole to selectively connect between the second opening on the first shield and a portion of the loading and unloading opening on the storage rack, the selective connection being made only to the portion through which the article passes. Such features make it possible to limit the area of the loading and unloading opening on the storage rack to a bare minimum, which contributes to more effective prevention of the contamination of the article. 
     Various preferred embodiments of the present invention allow a holding space alone to be kept clean instead of the entire transportation route of articles. Hence, the space that is to be kept clean is much smaller and contamination of the articles is successfully prevented. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a clean stocker according to Preferred Embodiment 1 of the present invention. 
         FIG. 2  shows an exemplary reticle chamber. 
         FIG. 3  shows how a pod containing a reticle is brought into a load port. 
         FIG. 4  shows how the pod is vertically separated. 
         FIG. 5  shows how the pod looks immediately after the reticle has been taken out. 
         FIG. 6  shows how the pod looks when closed again. 
         FIG. 7  schematically shows a transferring apparatus. 
         FIG. 8A  shows an exemplary operation of the transferring apparatus inside a shield. 
         FIG. 8B  shows an exemplary operation of the transferring apparatus inside the shield. 
         FIG. 8C  shows an exemplary operation of the transferring apparatus inside the shield. 
         FIG. 8D  shows an exemplary operation of the transferring apparatus inside the shield. 
         FIG. 9  shows how the transferring apparatus and the load port face each other. 
         FIG. 10  shows how the transferring apparatus and a reticle chamber face each other. 
         FIG. 11  shows how a loading and unloading opening appears on the reticle chamber in  FIG. 10 . 
         FIG. 12  schematically shows a clean stocker according to Preferred Embodiment 2 of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention shall be described hereinafter with reference to the drawings. 
     Preferred Embodiment 1 
       FIG. 1  schematically shows a clean stocker  100  which exemplifies an automated warehouse according to Preferred Embodiment 1 of the present invention. As shown in  FIG. 1 , the clean stocker  100  mainly includes a storage rack  110 , a load port  120 , a transferring apparatus  130 , a first shield  140 , a second shield  150 , an elevator guide  160 , and a cleaning unit (fan filter unit or FFU)  170 . The clean stocker  100  is preferably installed in a clean room of a semiconductor factory or a liquid crystal display factory, and separately stores reticles (articles) for exposure for either semiconductors or liquid crystal substrates, and pods (cases) for containing the reticles. 
     The storage rack  110  stores a reticle taken out of a pod. The structure of the storage rack  110  shall not be defined in particular. As the example in  FIG. 1  shows, the storage rack  110  preferably includes multiple reticle chambers  110   a . More specifically, the reticle chambers  110   a  are vertically arranged in a first column (on the left column in  FIG. 1 ) and a second column (on the right column in  FIG. 1 ) so that the first and second columns are provided around the transferring apparatus  130 . 
       FIG. 2  shows an exemplary reticle chamber  110   a . As shown in  FIG. 2 , a reticle chamber  110   a  includes an inner cover  111  that is cylindrical or substantially cylindrical, and an outer cover  112  which is slightly larger than the inner cover  111  and is cylindrical or substantially cylindrical. The inner cover  111  and the outer cover  112  respectively include an opening  111   a  and an opening  112   a  on their sides. 
     The inner cover  111  includes racks to place reticles and is fixed so that the opening  111   a  faces the transferring apparatus  130 . The inside of the inner cover  111  is kept clean by the cleaning unit  170 . The outer cover  112  covers the inner cover  111  and rotates around the inner cover  111 . 
     When the outer cover  112  rotates and the openings  111   a  and  112   b  shift away from each other (on the left in  FIG. 2 ), the loading and unloading of the reticles is denied (the reticle chamber  110   a  closed). When the outer cover  112  rotates and the openings  111   a  and  112   a  overlap with each other (on the right in  FIG. 2 ), the loading and unloading of the reticles is allowed (the reticle chamber  110   a  open). In other words, the overlapping openings  111   a  and  112   b  define a loading and unloading opening  113  on the reticle chamber  110   a.    
     The load port  120  operates as an interface to bring in and take out a reticle contained in a pod, as well as a pod opener (loading and unloading apparatus) to place and take the reticle in and out of the pod. 
       FIGS. 3 to 6  show operations of the load port  120  that works as a loading and unloading apparatus. Described with reference to  FIGS. 3 to 6  are a structure of the load port  120  and operations to take a reticle out of a pod. It is noted that the process below is reversed to place the reticle in the pod, and the details thereof shall be omitted. 
     The load port  120  includes a loading and unloading space  121  to be used to take a reticle out of a pod and place the reticle into the pod. Moreover, the loading and unloading space  121  is kept clean by the cleaning unit  170 . 
     As shown in  FIG. 3 , a pod  200  includes a cover  210  and a door  220  which are vertically separatable from each other. Moreover, on the top surface of the door  220 , multiple protrusions  221  are provided to support the reticle. 
     The load port  120  includes a locking portion  122  to lock the cover  210  and a platform  123  to keep the door  220  thereon. It is noted that the platform  123  operates as an elevator which vertically travels with the door  220  kept thereon. 
     The load port  120  includes an opening on the top thereof. The locking portion  122  is provided around the opening. The platform  123  is placed inside the load port  120  (specifically, in the loading and unloading space  121 ) to face the opening provided on the top of the load port  120 . The top of the load port  120  and the platform surface (top surface) of the platform  123  are to be positioned on the same level when the platform  123  ascends to the uppermost level. 
     The pod  200  is then placed on the platform  123  that ascends to the uppermost level. Hence, the opening of the load port  120  is closed by the pod  200 . In other words, the loading and unloading space  121  is specifically a space which is partitioned by the load port  120  and the cover  210  of the pod  200 . 
     The opening of the load port  120  is slightly larger than the door  220  and smaller than the cover  210 . Thus, when the platform  123  descends with the pod  200  placed thereon, the door  220  descends along with the platform  123  and the cover  210  is locked by the locking portion  122 . Hence, as shown in  FIG. 4 , the cover  210  and the door  220  are vertically separated from each other. 
     Next, the reticle  230  placed over the door  220  is removed by the transferring apparatus  130 , so that the load port  120  looks as shown in  FIG. 5 . When the platform  123  ascends with the door  220  placed thereon, the cover  210  is closed again with the door  220  as shown in  FIG. 6 . The empty pod  200  shown in  FIG. 6  is taken out of the load port  120  by a pod transporting apparatus (not shown) and stored on a pod storage rack (not shown). 
     The transferring apparatus  130  transfers a reticle between the storage rack  110  and the load port  120 .  FIG. 7  shows an exemplary structure of the transferring apparatus  130 . As shown in  FIG. 7 , the transferring apparatus  130  includes a holding space  131  to hold the reticle  230  therein. Using a sliding fork  133  which ejects from and retracts into the holding space  131  via the opening  132 , the transferring apparatus  130  transfers the reticle  230  between the storage rack  110  and the holding space  131  and between the holding space  131  and the pod  200  that is held in the loading and unloading space  121  of the load port  120 . Moreover, the holding space  131  is kept clean by the cleaning unit  170 . 
     As shown in  FIGS. 8A to 8D , the transferring apparatus  130  is placed inside a first shield  140 . The first shield  140  includes a cylinder  141  that accommodates the transferring apparatus  130 , and first to third openings  142 ,  143 , and  144  provided on the side of the cylinder  141 . 
     The first opening  142  is arranged to face the load port  120 . The second opening  143  is arranged to face each of the reticle chambers  110   a  that belong to the first column of the storage rack  110 . The third opening  144  is arranged to face each of the reticle chambers  110   a  that belong to the second column of the storage rack  110 . It is noted that the examples in  FIGS. 8A to 8D  show that the second opening  143  is positioned 90 degrees away from the first opening  142  in a clockwise direction, and the third opening  144  is positioned 180 degrees away from the first opening  142  in a clockwise direction, for example. 
     The transferring apparatus  130  is included in the cylinder  141  to be able to rotate and vertically travel inside the cylinder  141 . Together with the transferring apparatus  130 , the first shield  140  can vertically travel along the elevator guide  160  shown in  FIG. 1 . 
     A second shield  150 , as shown in  FIG. 9 , is attached to the outer sidewall of the cylinder  141  of the first shield  140 , and travels together with the transferring apparatus  130  and the first shield  140 .  FIG. 11  shows that the second shield  150  travels to a position to face a reticle chamber  110   a , and closes the loading and unloading opening  113  for reticles. The second shield  150  includes a connecting hole  151  to selectively connect between (i) one of the second and third openings  143  and  144  on the first shield  140  and (ii) a portion of the loading and unloading opening  113  on the reticle chamber  110   a . Here, the selective connection is made only to the portion through which the reticle passes. 
     The cleaning unit  170  may be an FFU, for example. Using a tube and the like, the cleaning unit  170  supplies the inside of the storage rack  110  and the loading and unloading space  121  of the load port  120  with clean dry air (CDA) refined by a DCA refining apparatus provided outside. The DCA keeps clean the inside of the storage rack  110  and the loading and unloading space  121 . The CDA is not directly supplied from the cleaning unit  170  to the holding space  131  of the transferring apparatus  130 ; however, when the holding space  131  connects to one of the storage rack  110  and the loading and unloading space  121 , the CDA is supplied from the storage rack  110  and the loading and unloading space  121  to the holding space  131  to keep the holding space  131  clean. In other words, the keeping clean means that the CDA supplied from the outside is directly or indirectly supplied to each of the units thorough the cleaning unit  170  that operates as an FFU. 
     With reference to  FIGS. 8A to 11 , described herewith are exemplary operations of the transferring apparatus  130  in transferring the reticle in the load port  120  to the storage rack  110 .  FIGS. 8A to 8D  show exemplary operations of the transferring apparatus  130  inside the first shield  140 .  FIGS. 9 to 11  show positional relationships between the first and second shields  140  and  150  and the reticle chamber  110   a . It is noted that the process below may be reversed to transfer a reticle on the storage rack  110  to the load port  120 , and the details thereof shall be omitted. 
     First, as shown in  FIG. 9 , the transferring apparatus  130 , the first shield  140  and the second shield  150  (hereinafter referred to as “the transferring apparatus  130  and the like”) are moved along the elevator guide  160  to a position where the first opening  142  of the first shield  140  faces the load port  120  (not shown in  FIG. 9 ). 
     Next, as shown in  FIG. 8A , the transferring apparatus  130  is rotated inside the cylinder  141  to the position where the opening  132  for the holding space  131  faces the first opening  142  of the first shield  140 . Hence, through the first opening  142 , the loading and unloading space  121  of the load port  120  and the holding space  131  of the transferring apparatus  130  are connected with each other. The transferring apparatus  130  then obtains the reticle in the load port  120  with the sliding fork  133  and stores the reticle in the holding space  131 . 
     Next, as shown in  FIG. 8B , the transferring apparatus  130  is elevated inside the cylinder  141  to the position where the opening  132  for the holding space  131  does not face any of the opening  142 , the opening  143 , or the opening  144 . Hence, the opening  132  for the holding space  131  is closed with the inner sidewall of the first shield  140 . 
     Then, as shown in  FIG. 8C , the transferring apparatus  130  in  FIG. 8B  is rotated inside the cylinder  141  as much as 90 degrees clockwise, for example. It is noted that, prior to the rotation, the transferring apparatus  130  is elevated so that the opening  132  for the holding space  131  is kept closed with the inner sidewall of the cylinder  141 . Such an operation contributes to preventing the CDA supplied from the cleaning unit  170  from leaking out of the holding space  131 . 
     Next, as shown in  FIG. 10 , the transferring apparatus  130  and the like are moved along the elevator guide  160  to a position where second opening  143  of the first shield  140  faces a reticle chamber  110   a . More specifically, the connecting hole  151  on the second shield  150  is to face a position of a rack, included in the reticle chamber  110   a , on which the reticle to be placed. 
     Then, as shown in  FIG. 11 , the outer cover  112  of the reticle chamber  110   a  is rotated so that the openings  111   a  and  112   a  match with each other to form the loading and unloading opening  113 . Here, the loading and unloading opening  113  on the reticle chamber  110   a  is closed with the second shield  150  except the position of the connecting hole  151 , which contributes to reducing the amount of the CDA to leak out of the reticle chamber  110   a.    
     Next, as shown in  FIG. 8D , the transferring apparatus  130  is lowered inside the cylinder  141  to the position where the opening  132  for the holding space  131  faces the second opening  143  of the first shield  140 . Hence, the reticle chamber  110   a  connects to the holding space  131  of the transferring apparatus  130  through the first opening  142  and the connecting hole  151 . The transferring apparatus  130  then transfers the reticle from the holding space  131  to the storage rack  110 , using the sliding fork  133 . 
     As a result of the above features, it is the inside of the reticle chamber  110   a , the loading and unloading space  121  of the load port  120  and the holding space  131  of the transferring apparatus  130  alone that the cleaning unit  170  has to keep clean. In other words, the unique features and arrangement described above eliminate the need of keeping the entire transportation route of reticles as a conventional clean stocker has to do so, which contributes to reducing the space to be cleaned. The resulting smaller cleaning space allows storage expenses to decrease and contributes to efficient prevention of contamination of the reticles. 
     It is noted that the above description is one non-limiting example, and therefore the present invention is not limited to the above-described example and many variations and modifications are possible within the scope of the present invention. For example, the order of the each of the operations may partly be changed. Specifically, the transferring apparatus  130  and the like may be first elevated to the position of the reticle chamber  110   a , and then the transferring apparatus  130  inside the first shield  140  in  FIG. 8B  may be rotated as shown in  FIG. 8C . Moreover, as an example, the transferring apparatus  130  preferably is elevated inside the cylinder  141  as shown in  FIG. 8B  and the transferring apparatus  130  preferably is lowered in the cylinder  141  as shown in  FIG. 8D ; instead, transferring apparatus  130  may be lowered prior to the rotation and elevated after the rotation. 
     Preferred Embodiment 2 
       FIG. 12  schematically shows the clean stocker  100  which exemplifies an automated warehouse according to Preferred Embodiment 2 of the present invention. It is noted that the details shared between Preferred Embodiments 1 and 2 shall be omitted, and mainly described here are the differences therebetween. 
     In the clean stocker  100  shown in  FIG. 12 , the load port  120  travels together with the transferring apparatus  130 . Moreover, the loading and unloading space  121  of the load port  120  and the holding space  131  of the transferring apparatus  130  are connected with each other. Furthermore, the first shield  140  covers all the load port  120  and the transferring apparatus  130  to close the loading and unloading space  121  and the holding space  131  that are connected with each other. The cleaning unit  170  (not shown in  FIG. 12 ) then supplies the interconnected loading and unloading space  121  and holding space  131  with CDA to keep the spaces clean. 
     The above features allow the reticle taken out of a case at the load port  120  to be transported to the storage rack  110  without moving the reticle out of a clean space. Furthermore, compared with the features described in Preferred Embodiment 1, the features in Preferred Embodiment 2 make it possible to simplify the structure of each constituent element. In other words, the first shield  140  does not have to be cylindrical or substantially cylindrical, nor does the transferring apparatus  130  have to be rotated therein either. In addition, the storage rack  110  may be a rotation rack like a conventional rack. 
     It is noted that Preferred Embodiments 1 and 2 show as an example the clean stocker  100  to store reticles; however, the present invention is not limited thereto. In other words, the present invention is applicable to automated warehouses that store any articles to be stored in clean spaces. 
     Although only some exemplary preferred embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications and variations are possible in the exemplary preferred embodiments without materially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention. 
     Preferred embodiments of the present invention are beneficial to automated warehouses to store articles in clean spaces. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.