Abstract:
A pod cover removing-installing apparatus is provided. The apparatus removes and installs a cover for an opening of a pod, an inside of which is kept extremely clean, by causing the cover to engage a door for an opening of a high cleanliness room, while maintaining high cleanliness of the pod and the room by closely attaching circumferences of the two openings. The apparatus includes a movable pod table and a linking pin provided on the pod table. The movable pod table has the pod installed thereon. The linking pin is substantially vertically aligned with respect to a moving direction of the pod table and comes in contact with a fixed side which is substantially vertically aligned with respect to the moving direction of the pod table. The fixed side is provided in a V-section groove provided on a bottom of the pod.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The instant application is a continuation-in-part of U.S. patent application Ser. No. 11/389,105, filed Mar. 27, 2006, now pending, which is a divisional of U.S. patent application Ser. No. 09/997,265, filed Nov. 30, 2001, now U.S. Pat. No. 7,11,027, which are incorporated by reference herein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a pod cover removing-installing apparatus for a pod which contains and transfers thin substrates such as semiconductor wafers from one space to another space while maintaining the cleanliness of both spaces. 
         [0004]    2. Related Art 
         [0005]      FIG. 21  shows an example of a conventional pod cover removing-installing apparatus. 
         [0006]    This conventional pod cover removing-installing apparatus  100  is provided with a diaphragm  101  which partitions off a high clean space A and a low clean space B, an opening  102  formed in the diaphragm  101  that serves as a passage between the high clean space A and the low clean space B, a door  103  which opens and closes the opening  102  of the diaphragm  101 , a latch mechanism  104  that latches the cover  203  of the pod  200  with two positioning pins  104   a ,  104   b  and two T-shaped keys  104   c ,  104   d  provided in the door  103 , and a table  105  provided in the low clean space B for mounting the pod  200 , which has three positioning pins  105   a ,  105   b ,  105   c  and one lock key  105   d.    
         [0007]    The pod  200  is a container with an extremely clean internal space C for containing a plurality of semiconductor wafers (25 wafers, for example). 
         [0008]    This pod  200  is provided with a main container body  201 , an opening  202  provided on one side of the main container body  201 , a cover  203  for opening and closing the opening  202 , the cover  203  having pin holes  204   a ,  204   b  for engaging the positioning pins  104   a ,  104   b , and key holes  204   c ,  204   d  for engaging T-shaped keys  104   c ,  104   d , and a bottom  205  having grooves  205   a ,  205   b ,  205   c  possessing a V-shaped section for engaging the positioning pins  105   a ,  105   b ,  105   c , and a key hole  205   d  for engaging the lock key  105   d.    
         [0009]    When the pod  200  is placed on the table  105 , the three positioning pins  105   a ,  105   b ,  105   c  engage the V-shaped section-possessing grooves  205   a ,  205   b ,  205   c . In this instance, switching on a lock button, not shown in the drawing, causes the lock key  105   d  to move upward, become angled, and engage the key hole  205   d . Then, the table  105  moves toward the diaphragm  101  for a prescribed distance (about 30 mm, for example), thereby causing the pod  200  to become attached to the diaphragm  101 . A sealing material such as an O-ring, not shown in the figure, is provided along the circumference of the opening  102  of the diaphragm  101  and the opening  202  of the pod  200 , to ensure close attachment of the openings and maintain cleanliness. 
         [0010]    The movement of the table  105  causes the cover  203  of the pod  200  to become closely attached to the door  203 , whereby the positioning pins  104   a ,  104   b  engage the pin holes  204   a ,  204   b  of the cover  203  and the T-shaped keys  104   c ,  104   d  engage the key holes  204   c ,  204   d . Thereafter, the T-shaped keys  104   c ,  104   d  are rotated 90 degrees by a rotary actuator or the like, not shown in the figure, whereby nails  204   e  to  204   h  are pulled in to release the lock between the container main body  201  and the cover  203 . 
         [0011]    Then, the door  103  is pulled into the space A (arrow D 1 ) and caused to descend (arrow D 2 ) by a drive mechanism, not shown in the figure, whereby the internal space C of the pod  200  and the internal space A of the partition board  101  are brought into communication while maintaining cleanliness. 
         [0012]    In the conventional technology mentioned above, the pod  200  is made from a resin by molding. Because the formed article may be distorted depending on molding conditions or temperatures, the positioning pins  104   a ,  104   b , the pin holes  204   a ,  204   b  of the cover  203 , and the key holes  204   c ,  204   d  are tapered to ensure a smooth removing-installing operation. 
         [0013]    However, when wafers with a large diameter (exceeding 300 mm) are placed in the pod  200 , a very stringent standard is necessary to secure an allowable distortion error of +/−0.5 mm. For this reason, significant difficulties may be encountered for performing the above operation in a stable manner. The following countermeasures are considered to overcome this problem. 
         [0014]    (A) One method is to precisely fabricate and adjust each pair of the main container body  201  and cover  203 , and assemble the apparatus using such a pair of the main container body  201  and cover  203 . However, this method requires readjustment of the apparatus when another pod is used. 
         [0015]    (B) Another method is to absorb a deviation between the main container body  201  and the cover  203  by designing the main container body  201  to be slightly movable. This method is effective for a small distortion, but ineffective for a large distortion. For example, even if there are no problems when the apparatus is new, distortions will be produced in two or three years after fabrication and the apparatus may not operate smoothly as time goes by. 
         [0016]    An object of the present invention is to provide a pod cover removing-installing apparatus for a pod which can open and close any cover for a variety of pods made, according to the SEMI standard, by a variety of manufacturers. These pods can satisfy an allowable distortion error and are capable of being normally operated even if conditions such as temperature, humidity, and use for such a variety of pods change, and the covers of these pods can be removed and installed without causing it to collide with any one of the parts of the pods. 
       SUMMARY OF THE INVENTION 
       [0017]    In an aspect of the present invention, a pod cover removing-installing apparatus is provided. The apparatus removes and installs a cover ( 603 ) for an opening of a pod ( 600 ), an inside of which is kept extremely clean, by causing the cover to engage a door for an opening of a high cleanliness room, while maintaining high cleanliness of the pod and the room by closely attaching circumferences of the two openings. The apparatus includes a movable pod table ( 15 ) and a linking pin ( 15   a - 15   c ) provided on the pod table. The movable pod table has the pod installed thereon. The linking pin is substantially vertically aligned with respect to a moving direction (M) of the pod table and comes in contact with a fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) which is substantially vertically aligned with respect to the moving direction of the pod table. The fixed side is provided in a V-section groove ( 605   a - 605   c ) provided on a bottom of the pod. 
         [0018]    In another aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the moving direction (M) of the pod table ( 15 ) is set in a horizontal direction, an axis of the linking pin ( 15   a - 15   c ) is vertically aligned with the horizontal direction, the fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) is a vertical inner wall provided in a recessed portion ( 605   a - 2 ,  605   b - 2  and  605   c - 2 ) of the V-section groove ( 605   a - 605   c ), and the linking pin engages with the vertical inner wall. 
         [0019]    In still another aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the linking pin ( 15   a - 15   c ) has a first flat surface ( 15   a - 7 ) on an end portion thereof, the recessed portion ( 605   a - 2 ,  605   b - 2  and  605   c - 2 ) has a second flat surface ( 605   a - 7 ) on a bottom portion thereof, and the first flat surface and the second flat surface come into surface contact with each other so as to determine a vertical position of the pod. 
         [0020]    In yet another aspect of the present invention, a pod cover removing-opening apparatus further including a detector is provided. The detector detects an occurrence of surface contact between the first flat surface and the second flat surface 
         [0021]    In a further aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the linking pin has an abutting portion ( 811 - 1 ,  915   a - 8 ) that comes into contact with a slope ( 205   a - 6 ,  605   a - 6 ) of the V-section groove ( 205   a ,  605   a ) so as to determine a vertical position of the pod ( 200 ). 
         [0022]    In a still further aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the moving direction (M) of the pod table ( 15 ) is set in a horizontal direction, the linking pin ( 15   a - 15   c ) has a guide portion ( 15   a - 6 ) on an end portion thereof, the guide portion being sectionally configured to be tapered, and the guide portion allows the fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) to be guided into contact with the linking pin. 
         [0023]    In a yet further aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the moving direction (M) of the pod table ( 915 ) is set in a horizontal direction, the linking pin ( 915   a ) has a guide portion ( 915   a - 6 ) on an end portion thereof, the guide portion being sectionally configured to be circular, and the guide portion allows the fixed side ( 605   a - 1 ) to come into contact with the linking pin. 
         [0024]    In another aspect of the present invention, a pod cover removing-installing apparatus is provided, which further includes a guide portion ( 811 - 1 ), a base member ( 811 ) and a biasing member ( 816 ). The guide portion abuts with a slope ( 605   a - 6 ) of the V-section groove ( 605   a ) so as to guide the fixed side ( 606   a - 1 ) to the linking pin ( 815   a ). The base member supports the linking pin movably in an axial direction thereof. The biasing member biases the linking pin. In addition, the slope ( 605   a - 6 ) of the V-section groove thrusts the linking pin into the base member while the guide portion is guiding the fixed side to the linking pin. The biasing member urges the linking pin to project from the base member when the guide portion finishes guiding the fixed side to the linking pin. 
         [0025]    In still another aspect of the present invention, a pod cover removing-installing apparatus is provided, which further includes a detector ( 818 ,  818 - 1  and  818 - 2 ) that detects the projection of the linking pin ( 815   a ) from the base member ( 811 ). 
         [0026]    In yet another aspect of the present invention, a pod cover removing-installing apparatus is provided, in which the guide portion ( 811 - 1 ) is an abutting portion ( 811 - 1 ) that abuts with the slope ( 605   a - 6 ) of the V-shaped groove ( 605   a ) so as to determine a vertical position of the pod ( 600 ) after the guide portion finishes guiding the fixed side ( 605   a - 1 ) to the linking pin ( 815   a ). 
         [0027]    In a further aspect of the present invention, a pod ( 600 ) with high cleanliness having a cover ( 603 ) for an opening is provided. The cover is removed and installed by a pod cover removing-installing apparatus when the cover is engaged with a door for an opening of a room with high cleanliness, while high cleanliness of the pod and the room is maintained by closely attaching circumferences of the two openings. The pod includes a V-section groove ( 605   a - 605   c ) provided on a bottom of the pod. The V-section groove has a fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) substantially vertically aligned with respect to a moving direction (M) of a movable table ( 15 ) of the pod cover removing-installing apparatus. The fixed side comes into contact with a linking pin ( 15   a - 15   c ) that is substantially vertically aligned with respect to the moving direction and provided on the movable pod table. 
         [0028]    In a still further aspect of the present invention, a pod is provided, in which the moving direction (M) of the movable pod table ( 15 ) is set in a horizontal direction, the fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) is a vertical inner wall provided in a recessed portion ( 605   a - 2 ,  605   b - 2  and  605   c - 2 ) of the V-section groove ( 605   a - 605   c ), and the vertical inner wall engages with the linking pin ( 15   a - 15   c ). 
         [0029]    In a yet further aspect of the present invention, a pod is provided, in which the recessed portion ( 605   a - 2 ,  605   b - 2  and  605   c - 2 ) has a first flat surface ( 605   a - 7 ) on a bottom portion thereof, the linking pin ( 15   a - 15   c ) has a second flat surface ( 15   a - 7 ) on an end portion thereof, and the first flat surface and the second flat surface come into surface contact with each other so as to determine a vertical position of the pod. 
         [0030]    In another aspect of the present invention, a system for removing and installing a cover of a pod is provided. The system includes a pod ( 600 ) that is internally kept clean and a cover removing-installing unit. The cover removing-installing unit removes and installs a cover ( 603 ) for an opening of the pod by causing the cover to engage a door for an opening of a high cleanliness room, while maintaining high cleanliness of the pod and the room by closely attaching circumferences of the two openings. The cover removing-installing unit includes a movable table ( 15 ) and a linking pin ( 15   a - 15   c ). The linking pin is substantially vertically aligned with respect to a moving direction (M) of the movable table and provided on the movable table. The pod has a fixed side ( 605   a - 1 ,  605   b - 1  and  605   c - 1 ) that is substantially vertically aligned with respect to the direction of the movable table and is provided in a V-section groove ( 605   a - 605   c ) provided on a bottom of the pod. The fixed side comes into contact with the linking pin. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]      FIG. 1  is a perspective view showing an outline of a first embodiment of the cover removing-installing apparatus for a pod of the present invention; 
           [0032]      FIG. 2  is a front view of the first embodiment of the cover removing-installing apparatus for a pod of the present invention; 
           [0033]      FIGS. 3(   a ) and  3 ( b ) are enlarged views of the part III of  FIG. 2  and show the fine adjustment mechanism for the pod cover removing-installing apparatus of the first embodiment; 
           [0034]      FIGS. 4(   a ) and  4 ( b ) are enlarged views of the part IV of  FIG. 2  and show the centering mechanism for the pod cover removing-installing apparatus of the first embodiment; 
           [0035]      FIG. 5  is a cross sectional view along the line V-V of  FIG. 2  and shows the holding mechanism of the pod cover removing-installing apparatus of the first embodiment; 
           [0036]      FIG. 6(   a ) is a perspective view and  FIG. 6(   b ) is a cross sectional view along the line VI-VI of  FIG. 2 , showing an eccentric transmission mechanism for the pod cover removing-installing apparatus of the first embodiment; 
           [0037]      FIG. 7  is a cross sectional view along the line VII-VII of  FIG. 2  and shows the positioning securing means of the pod cover removing-installing apparatus of the first embodiment; 
           [0038]      FIG. 8  is a block diagram showing a control means for the pod cover removing-installing apparatus of the first embodiment; 
           [0039]      FIG. 9  is a flowchart showing an operational example (cover opening operation  1 ) for the pod cover removing-installing apparatus of the first embodiment; 
           [0040]      FIG. 10  is a flowchart showing an operational example (cover opening operation  2 ) for the pod cover removing-installing apparatus of the first embodiment; 
           [0041]      FIG. 11  is a flowchart showing an operational example (cover closing operation  1 ) for the pod cover removing-installing apparatus of the first embodiment; 
           [0042]      FIG. 12  is a flowchart showing an operational example (cover opening operation  2 ) for the pod cover removing-installing apparatus of the first embodiment; 
           [0043]      FIG. 13  is a front view showing the main part of a second embodiment of the cover removing-installing apparatus for a pod of the present invention; 
           [0044]      FIGS. 14(   a ) and ( b ) are drawings showing the main part of the second embodiment of the pod cover removing-installing apparatus of the present invention, wherein  FIG. 14(   a ) is a cross sectional view along the line A-A of  FIG. 13  and  FIG. 14(   b ) is a cross sectional view along the line B-B of  FIG. 13 ; 
           [0045]      FIGS. 15(   a ) and ( b ) are drawings showing the main part of the second embodiment of the pod cover removing-installing apparatus of the present invention, wherein  FIG. 15(   a ) is a drawing viewed from the arrow E in  FIG. 15(   b ) and  FIG. 15(   a ) is a cross sectional view along the line C-C of  FIG. 13 ; 
           [0046]      FIGS. 16(   a ) and ( b ) are cross sectional views along the line D-D of  FIG. 13  showing the main part of the second embodiment of the cover removing-installing apparatus for a pod of the present invention; 
           [0047]      FIG. 17  shows a holding mechanism of the pod cover removing-installing apparatus according to the third embodiment; 
           [0048]      FIGS. 18(   a ), ( b ), and ( c ) are drawings showing a positioning member of the pod cover removing-installing apparatus according to the fourth embodiment; 
           [0049]      FIGS. 19(   a ), ( b ), ( c ), and ( d ) are drawings showing a table positioning member of the pod cover removing-installing apparatus according to the fifth embodiment; 
           [0050]      FIGS. 20(   a ) and ( b ) are drawings showing a positioning member of the pod cover removing-installing apparatus according to the sixth embodiment; 
           [0051]      FIG. 21  shows an example of a conventional pod cover removing-installing apparatus; 
           [0052]      FIG. 22(   a ) is a partial sectional view showing a pod and table according to the fifth embodiment.  FIG. 22(   b ) is a bottom view showing the pod; 
           [0053]      FIGS. 23(   a ) and  23 ( b ) are sectional views showing a V-section groove and a positioning pin according to the fifth embodiment, which are engaged with each other; 
           [0054]      FIG. 24  is a sectional view showing a V-section groove of a pod engaging with a positioning pin of a cover removing-installing apparatus according to the seventh embodiment; 
           [0055]      FIG. 25  is a sectional view showing a positioning pin of a cover removing-installing apparatus engaging with a V-section groove of a pod according to the seventh embodiment; 
           [0056]      FIG. 26  is a sectional view showing a positioning pin of a cover removing-installing apparatus engaging with a V-section groove of a pod according to the eighth embodiment; and 
           [0057]      FIG. 27  is a sectional view showing a positioning pin of a cover removing-installing apparatus engaging with a V-section groove of a pod according to the ninth embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0058]    The present invention will be described in more detail by way of preferred embodiments with reference to the attached drawings. 
       a. First Embodiment 
       [0059]      FIGS. 1 and 2  are drawings showing a first embodiment of the pod cover removing-installing apparatus of the present invention, wherein  FIG. 1  is a perspective view showing an outline and  FIG. 2  is a plan view of the apparatus. 
         [0060]    This pod cover removing-installing apparatus is provided with a diaphragm  11 , an opening  12 , a door  13  which opens and closes the opening  12  of the diaphragm  11 , two positioning pins  14   a ,  14   b  and two T-shaped keys  14   c ,  14   d , a latch mechanism  14  which opens and closes a cover  203  of a pod  200 , and the like. 
         [0061]    In the first embodiment, the door  13  is provided with a base plate  13 A and a position adjusting plate  13 B movable in the direction vertical to the plane so that its position can be adjusted with respect to the base plate  13 . 
         [0062]    The door  13  is provided therein with four fine adjustment mechanisms  20 , two centering mechanisms  30 , four holding mechanisms  40 , two eccentric transmission mechanisms  50 , one positioning fixing means  60 , and the like. 
         [0063]      FIGS. 3(   a ) and  3 ( b ) are enlarged views of the part III of  FIG. 2  and show the fine adjustment mechanism for the pod cover removing-installing apparatus of the first embodiment. 
         [0064]    The fine adjustment mechanism  20  supports the position adjusting plate  13 B movable in the direction vertical to the plane and exactly adjusts the position of the positioning pins  14   a  and  14   b . This fine adjustment mechanism  20  is provided in the four corners of the position adjusting plate  13 B (see  FIG. 1 ), each having a fixture  21  for fastening and securing the base plate  13 A using a thread  21   a , a female screw  22  for keeping the fixture  21  from loosening, a receiving member  23  of free bearings and the like inserted into the fixture  21 , a ball  24  rotatively supported by the receiving member  23 , an opposing plate  25  provided in the base plate frame  13 A- 1  on the opposing side, a receiving member  26  provided in the opposing plate  25 , a ball  27  rotatively supported in the receiving member  26 , a guide plate  28  provided on the side of position adjusting plate  13 B and movably squeezed by the ball  24  and the ball  27 . 
         [0065]    The fine adjustment mechanism  20  is designed so that in the initial state in which the positioning pins  14   a ,  14   b  engage the pin holes  204   a ,  204   b  of the pod  200  (see  FIG. 21 ), tapered tips of the positioning pins  14   a ,  14   b  move a prescribed distance (e.g. 3 mm in every direction) vertically to the plane, while the tapered tips match the tapered pin holes  204   a ,  204   b . For this reason, even if there is some error in the position of the pin holes  204   a ,  204   b  of the pod  200 , the positioning pins  14   a ,  14   b  can easily engage these pin holes without colliding. 
         [0066]      FIGS. 4(   a ) and  4 ( b ) are enlarged views of the part IV of  FIG. 2  and show the centering mechanism for the pod cover removing-installing apparatus of the first embodiment. 
         [0067]    The centering mechanism  30  is a mechanism for causing the position adjusting plate  13 B to return to the center. The centering mechanism  30 , consisting of two systems, one in the horizontal direction (x direction) and the other in the vertical direction (y direction), is provided with press boards  31   x ,  31   y , securing members  32   x ,  32   y  for securing the press boards  31   x ,  31   y  in the base plate  13 A, coil springs  33   x ,  33   y  for moving the press boards  31   x ,  31   y  to the center, securing members  34   x ,  34   y  for securing the other ends of the coil springs  33   x ,  33   y  to the base plate  13 A, guide pieces  35 ,  37  which come into contact with the press boards  31   x ,  31   y , securing members  36 ,  38  for securing the guide pieces  35 ,  37  in the position adjusting plate  13 B and base plate  13 A, and the like. 
         [0068]    The press board  31   x  aligns the guide pieces  35 ,  37  on a straight line in the X direction. In the same manner, the press board  31   y  aligns the guide pieces  35 ,  37  on a straight line in the Y direction. The position adjusting plate  13 B is centered by these actions. 
         [0069]    Although omitted from  FIG. 2 , a mechanism which is the same but symmetrical with the mechanism shown in the upper right side is provided in the upper left side of the  FIG. 2 . 
         [0070]    Because the position adjusting plate  13 B can move vertical to the plane with respect to the base plate  13 A by means of the fine adjustment mechanism  20 , the centering mechanism  30  always causes the position adjusting plate  13 B to be positioned in the previously determined center position (the engaging position without an error) in the initial state in which the positioning pins  14   a ,  14   b  engage the pin holes  204   a ,  204   b  of the pod  200  (see  FIG. 21 ). 
         [0071]      FIG. 5  is a cross sectional view along the line V-V of  FIG. 2  and shows the holding mechanism of the pod cover removing-installing apparatus of the first embodiment. 
         [0072]    The holding mechanism  40  holds the position adjusting plate  13 B to the cover  203  of the pod  200  at the position where the positioning pins  14   a ,  14   b  engage. The holding mechanism  40  has a securing plate  41  provided in a base plate frame  13 A- 1 , a joint  43  connected with this securing plate  41  through the O-ring  42 , having a nozzle (not shown in the figure) connected to a vacuum pressure source, and an absorption pad  44  provided in the joint  43  which is capable of being attached to the position adjusting plate  13 B. 
         [0073]    Because the position adjusting plate  13 B can move vertical to the plane with respect to the base plate  13 A by means of the fine adjustment mechanism  20 , the holding mechanism  40  can hold the positioning pins  14   a ,  14   b  to engage the pin holes  204   a ,  204   b  of the pod  200  (see  FIG. 21 ). This structure ensures that the container maintains the same position as the position before removal when the cover  203  has been once removed and returned thereafter. Therefore, the cover can be closed without impediment. 
         [0074]      FIG. 6(   a ) is a perspective view and  FIG. 6(   b ) is a cross sectional view along the line VI-VI of  FIG. 2 , showing an eccentric transmission mechanism for the pod cover removing-installing apparatus of the first embodiment. 
         [0075]    The T-shaped key  14   c  ( 14   d ) is provided in a prescribed position of the position adjusting plate  13 B to engage the key hole  204   c  ( 204   d ) of the cover  203  to lock the cover  203 , and driven by a lock drive mechanism  70  (see  FIG. 2 ). This lock drive mechanism  70  is provided on the side of the base plate  13 A and rotates in either direction around the axis of the T-shaped key  14   c  ( 14   d ) to perform locking or unlocking movements. 
         [0076]    Because it is desirable to make the position adjusting plate  13 B light for ease of movement, the lock drive mechanism  70  and the like are preferably installed on the base plate  13 A. For this reason, an eccentric transmission mechanism  50  is provided to transmit a driving force from the lock drive mechanism  70  to the T-shaped key  14   c  ( 14   d ). 
         [0077]    This eccentric transmission mechanism  50  allows a deflection of the base plate  13 A and position adjusting plate  13 B in the direction vertical to the plane and transmits a rotational force of the lock drive mechanism  70  to the T-shaped key (locking member)  14   c  ( 14   d ). 
         [0078]    As shown in  FIGS. 6(   a ) and  6 ( b ), the eccentric transmission mechanism  50  has a driving lever  51  connected to the lock drive mechanism  70 , a rotation lever  52  rotatively connected to the driving lever  51 , a bearing  54  supporting the rotation lever  52  on the base plate  13 A in a freely rotative manner, transmission rollers  53 A,  53 B provided on the rotation lever  52 , a slide disc  55  having grooves  55   a ,  55   b  orthogonally provided on both sides, into which the transmission rollers  53 A,  53 B and transmission rollers  56 A,  56 B are respectively inserted, a rotation board  57  provided on the same axis with the T-shaped key  14   c  ( 14   d ), a bearing  58  having the transmission rollers  56 A,  56 B provided therein and supporting the axis of the rotation board  57  and the T-shaped key  14   c  ( 14   d ) on the position adjusting plate  13 B in a freely rotative manner, and the like. 
         [0079]    The eccentric transmission mechanism  50  transmits a rotational force of the lock drive mechanism  70  to the T-shaped key  14   c  ( 14   d ), even if the position adjusting plate  13 B moves from its original position within a movable range in the direction vertical to the plane. 
         [0080]    Here, as shown in  FIG. 2 , the lock drive mechanism  70  is provided with a motor  71 , a drive screw  73  to which the rotation of the motor  71  is transmitted by a belt  72 , a slide axis  74  arranged in parallel with the drive screw  73 , a moving block  75  freely slidably supported in the slide axis  74  and driven by a drive screw  73 , a bearing  76  secured on a moving block  75  and engaging a long hole in the transmission lever  51 , and the like. 
         [0081]    When the bearing  76  is in the position (a), the rotation lever  52  is in the position (a). When the bearing  76  moves to the right and comes to the position (b), the rotation lever  52  rotates. This causes the transmission lever  51  to move that distance and to descend to the point indicated by a chain line connected by two dots. Because the bearing  76  is secured on the moving block  75 , the horizontal level of the position (b) remains the same as that of the position (a). Because of this, a deviation of the engaging position of the transmission lever  51  and the bearing  76  is absorbed by the long hole of the transmission lever  51 . 
         [0082]      FIG. 7  is a cross sectional view along the line VII-VII of  FIG. 2  and shows the positioning securing means of the pod cover removing-installing apparatus of the first embodiment. 
         [0083]    The position securing means  60  secures the positioning pins  14   a ,  14   b  in the pin holes  204   a ,  204   b  when the positioning pins  14   a ,  14   b  engage the pin holes (the parts to be engaged)  204   a  and  204   b  of the pod  200  and their positions are determined. 
         [0084]    The position securing means  60  of this embodiment has a passage  61  provided in the axial direction of the positioning pin  14   a  ( 14   b ), a passage  62  provided in the vertical direction of the passage  61  and joining therewith, a stretch member  63  formed from rubber such as neoprene provided around the circumference of the positioning pin  14   a  ( 14   b ) and capable of stretching according to an increase or decrease in the internal pressure, a pipe  64  connected with the passage  61 , a securing member  65  for securing the pipe  64  at the rear end of the positioning pin  14   a  ( 14   b ), and the like. 
         [0085]    In this position securing means  60 , pipe  64  is connected to a pneumatic circuit or a vacuum circuit, not shown in the figure, which causes the internal pressure of the passages  61 ,  62  to increase or decrease, thereby causing the stretch member  63  to expand or contract, causing the gap between the positioning pins  14   a ,  14   b  and the pin holes  204   a ,  204   b  to be filled out. The positioning pins  14   a ,  14   b  are secured in the position in this manner. 
         [0086]      FIG. 8  is a block diagram showing a control means for the pod cover removing-installing apparatus of the first embodiment, and  FIGS. 9-12  are flow charts showing operations of the cover removing-installing apparatus. 
         [0087]    The control means  80  has various sensors  81  for detecting the positions and the like of each moving part, a controller  82  which produces various control signals to control each drive part, described later, based on the position detection signals from the sensors  81 , a driver  83  for converting control signals from the controller  82  into drive signals conforming to each drive part, and a drive part driven based on the drive signals from the driver  83 , including a position-keeping valve  84  which controls the flow of the air pressure to the holding mechanism  40 , a cover securing valve  85  which controls the flow of the air pressure to a cover securing means  60 , a cover locking motor  71  of a lock drive means  70 , a container moving motor  86 , a door moving motor  87 , and the like. 
         [0088]    Next, the cover opening operation will be described referring to  FIGS. 9 and 10 . 
         [0089]    The controller  82  drives the position-keeping valve  84  to the release side (Step  101 , the step is hereinafter referred to as “S”) and, upon confirmation of release with a sensor (S 102 , YES), drives the container moving motor  86  to move the pod  200  forward (S 103 ), then, upon confirmation that the pod  200  has come to the joining position (S 104 , YES), stops the container moving motor  86 . 
         [0090]    Because the holding mechanism  40  is canceled in this state by the position-keeping valve  84 , the position adjusting plate  13 B is not only free, but also has been moved to the center by the centering mechanism  30 . When the pod  200  comes to the joining point, the position adjusting plate  13 B can be moved by the fine adjustment mechanism  20 , enabling the complete joining of the cover  203  of the pod  200  and the door  13  even though the pin holes  204   a  and  204   b  of the pod  200  deviate in the allowable range with respect to the positioning pins  14   a ,  14   b.    
         [0091]    Next, the cover locking motor  71  is driven to the unlock side (S 105 ) and the T-shaped keys  14   c  and  14   d  are rotated to retract the nails  204   e - 204   h  of the cover  203 . When the sensor confirms that the nails  204   e - 204   h  have been retracted (unlock) (S 106 , YES), the cover securing valve  85  is driven to the securing side (S 107 ) to expand the stretch member  63  of the positioning pins  14   a ,  14   b , confirming the securing of the pin holes  204   a ,  204   b  with the sensor (S 108 , YES). 
         [0092]    In the final stage of the operation S 107 , even if there is a deviation between the positioning pins  14   a ,  14   b  and pin holes  204   a ,  204   b , and the position adjusting plate  13 B has been moved, the T-shaped keys  14   c ,  14   d  can rotate due to the eccentric transmission mechanism  50 . 
         [0093]    Moreover, accurate positioning is possible because the pin holes  204   a ,  204   b  are secured by expanding the stretch member  63  of the positioning pins  14   a ,  14   b.    
         [0094]    Next, as shown in  FIG. 10 , the position-keeping valve  84  is driven to the hold side (S 109 ), confirming the holding with the sensor (S 110 , YES), and causing the door to reverse by driving the door moving motor  87  (S 111 ). Upon confirmation that the door has reversed (S 112 , YES), the door moving motor  87  is further driven to move the door downward (S 113 ). When the door has reached the lower limit (S 114 , YES), the operation to terminate the process is stopped. 
         [0095]    In this state, the position-keeping valve  84  is driven to the hold side and holds the position of the position adjusting plate  13 B in its original position in the later-described door closing operation. Therefore, the door does not collide with the opening  202  of the pod  200  when closed. 
         [0096]    Next, the cover closing operation will be described referring to  FIGS. 11 and 12 . 
         [0097]    Referring to  FIG. 11 , the controller  82  drives the door moving motor  87  to elevate (S 201 ) to the upper limit point (S 202 , YES), then to go forward (S 203 ) until it starts rejoining the pod  200 . Upon confirmation of the initiation of rejoining by a sensor (S 204 , YES), the position-keeping valve  84  is driven to the release side (S 205 ). Upon confirmation of the release by a sensor (S 206 , YES), the door moving motor  87  is driven forward (S 207 ) until rejoining is complete, whereupon the door moving motor  87  is stopped and the rejoining with the pod  200  is confirmed by a sensor (S 208 ). 
         [0098]    Next, the cover securing valve  85  is driven to the release side (S 209 ) to cause the stretch member  63  of the positioning pins  14   a ,  14   b  to become contracted. The release from the pin holes  204   a ,  204   b  is confirmed by a sensor (S 210 , YES). The cover locking motor  71  is driven to the lock side (S 211 ) to rotate the T-shaped keys  104   c ,  104   d  and cause the nails  204   e  to  204   h  to protrude and lock the cover, which is confirmed by a sensor (S 212 , YES). 
         [0099]    Finally, the container moving motor  86  is driven to move the pod  200  backward (S 213 ). Upon confirmation by a sensor that the pod  200  has reversed (S 104 , YES), the container moving motor  86  is stopped to terminate the cover closing operation. 
       b. Second Embodiment 
       [0100]      FIGS. 13-16(   a ) and ( b ) show the main parts of the pod cover removing-installing apparatus of the second embodiment, wherein  FIG. 13  is a front view,  FIG. 14(   a ) is a cross sectional view along the line A-A of  FIG. 13 ,  FIG. 14(   b ) is a cross sectional view along the line B-B of  FIG. 13 ,  FIG. 15(   a ) is a view from the direction of the arrow E of  FIG. 15(   b ),  FIG. 15(   b ) is a cross sectional view along the line C-C of  FIG. 13 , and  FIGS. 16(   a ) and ( b ) are cross sectional views along the line D-D of  FIG. 13 . 
         [0101]    The second embodiment of the pod cover removing-installing apparatus has, in addition to the structure of the first embodiment, a cover securing means which secures the cover  203  to the door  13  by retracting the lock pins  13   a ,  13   b  (by pulling down in  FIG. 13 ) to the door  13  side. 
         [0102]    A linear motion from a drive means, not shown in the drawing, to a rack  312  in  FIG. 13  rotates a pinion gear  311  which engages the rack  312 . A disc  310  is coaxially screwed to the pinion gear  311 . 
         [0103]    The disc  310  can rotate by 180 degrees, causing the T-shaped key  14   c  ( 14   d ) to rotate in the first 90-degree rotation and drawing the T-shaped key  14   c  ( 14   d ) to the direction of the arrow F in the next 90-degree rotation, thereby securing the cover  203  to the door  13  (the cover securing means). 
         [0104]    A disc  309  is installed on an axis  309   a  in a freely rotative manner within an angle of 90 degrees. The axis  309   a  is screwed to the base plate  13 A. A rotation from the disc  310  is transmitted to the disc  309  via a rotor (bearing) which is screwed to the groove formed on the bottom of the disc  309  and the top of the disc  310 . 
         [0105]    A rotating disc  306  is connected to the rotating disc  309  via a moving body  308  and a bearing  307 , as shown in  FIG. 14(   a ). The moving body  308  and the bearing  307  allow the rotation of the rotating disc  309  and the rotating disc  306 , even if these deviate in any direction, i.e. up and down, right and left, or front and back. 
         [0106]    Because not only the disc  305  is connected to the disc  306  via a support  320  and a bush  321  ( FIG. 13 ), but also these parts are pressed together by a spring, the discs  305  and  306  rotate as an integral body. 
         [0107]    The T-shaped key  14   c  ( 14   d ) is held on a holding base  302  movable in the axial direction. A push-down board  303  is connected to the holding base  302 . The push-down board  303  is provided with a bearing  304  which maintains contact with the surface of the disc  305  while rotating. The disc  305  is pushed upward by the spring  301 . The contact of the disc  305  with the holding base  302  ensures accurate determination of the position of the T-shaped key  14   c  ( 14   d ) in the axial direction. 
         [0108]    The T-shaped key  14   c  ( 14   d ) rotates 90 degrees by a first 90-degree rotation of the disc  310  according to the above mechanism to complete a lock (or unlock) operation. In this instance, the rotation can be transmitted even if the rotating disc  309  and the rotating disc  306  deviate in any direction (up and down, right and left, or front and back) due to the existence of the moving body  308  and the bearing  307  (eccentric transmission mechanism). 
         [0109]    As shown in  FIGS. 13 and 15(   a ) and ( b ), a roller  318  is attached to a bracket  322  provided in the base plate  13 A and comes into contact with the bottom of the disc  310  to prevent downward deflection of the disc  310 . 
         [0110]    A groove  310   a  is formed on the surface of the disc  310  as shown in  FIG. 16(   b ). The bottom of the groove  310   a  slopes from the highest point  310   b  to the lowest point  310   c . A bearing  313  enters the groove  310   a  and moves. The bearing  313  is installed on the bottom of the support member  324  which is provided in a freely slidable manner in the collar  323  installed on the bracket  322 . The support member  324  has a cylindrical upper portion into which a support column  316  is inserted through a spring  315 . A pin  314  is provided in the support member  324  to prevent its rotation. Because the pin  314  engages a long hole provided in the bracket  322 , the support member  324  does not rotate even if it moves up and down. 
         [0111]    A base seat  317  is screwed to a push-down board  303 , with the bottom in contact with the top of the support member  316 . The push-down board  303  is freely rotatively supported by a pin  319  and rotates counterclockwise in the  FIG. 13  by a force pressing the base seat  317  upward (arrow G), thereby transmitting a push-down force (arrow F) to a bearing  304  which is provided on the other end. 
         [0112]    Specifically, the push-down board  303  pushes down the T-shaped key  14   c  ( 14   d ) via the above-described mechanism in the next 90-degree rotation of the disc  310 , whereby the cover  203  of the pod  200  may be secured to the door  13 . 
         [0113]    The second embodiment enables one driving force to cause rotation of the T-shaped key  14   c  ( 14   d ) and a pull-in operation of the T-shaped key  14   c  ( 14   d ) to secure the cover  203  to the door  13 . In addition, the apparatus of the second embodiment is also provided with an eccentric transmission mechanism which allows deviation of the base plate  13 A and the position adjusting plate  13 B. 
       c. Third Embodiment 
       [0114]      FIG. 17  shows a holding mechanism of the pod cover removing-installing apparatus according to a third embodiment. 
         [0115]    A holding mechanism  440  has a securing plate  441  provided in a base plate frame (not shown), a base plate  445  provided on the securing plate  441 , a main body  443  connected to the base plate  445  through an O-ring  442  and having a nozzle connected to a vacuum pressure source  451 , an absorption pad  444  provided in the main body  443  and having a seat  444   a  to attach to the position adjusting plate  13 B. 
         [0116]    In this embodiment, a space  446  is formed between the absorption pad  444  and the base plate  445 . The base plate  445  is provided with a nozzle  447  to connect the space  446  to an air pressure source  452 . 
         [0117]    A vacuum pressure source  451  is connected to the nozzle of the main body  443  through solenoid valves SV 1  and SV 2 . The air pressure source  452  is connected to the nozzle  447  through a solenoid valve SV 3 . 
         [0118]    The NC port of the solenoid valve SV 1  spatially communicates with the vacuum pressure source  451 , the NO port with the atmosphere, and the C port with the C port of the solenoid valve SV 2 . The NC port of the solenoid valve SV 2  spatially communicates with the nozzle  443 , and the NO port with NC port of the solenoid valve SV 3 . The C port of the solenoid valve SV 3  spatially communicates with the air pressure source  452  and the NO port is shut off. 
         [0119]    If the solenoid valves SV 1 , SV 2 , and SV 3  are on the NC port side as shown in  FIG. 17 , with the vacuum pressure source  451  being evacuated and high pressure air being supplied from the air pressure source  452 , the seat  444   a  of the adsorption pad  444  is pushed to the position adjusting plate  13 B side by the pressure of the space  446  and the pressure of the space  448  inside the seat part  444   a  becomes negative, thereby accelerating the adherence of the adsorption pad  444 . 
         [0120]    On the other hand, if the solenoid valve SV 1  is switched to the NO port side to open the space  448  to the atmosphere, then the solenoid valves SV 2 , SV 3  are switched to the NO port side to open the space  446  to the atmosphere, the solenoid valve SV 1  is switched to the NC port side, and the space  446  is adsorbed to accelerate release of the adsorption pad  444 . 
         [0121]    The third embodiment thus accelerates the adherence and release operations of the position adjusting plate  13 B. In addition, because the seat part  444   a  separates from the position adjusting plate  13 B during the release operation, the position adjusting plate  13 B can move smoothly. 
       d. Fourth Embodiment 
       [0122]      FIGS. 18(   a ), ( b ), and ( c ) show a positioning member of the pod cover removing-installing apparatus according to a fourth embodiment. 
         [0123]      FIG. 18(   c ) shows a conventional system. In this system, if the deviation of the positioning pin  14   a  and the pin hole  204   a  becomes larger than δ0=1−1.5 mm, the positioning pin  14   a  may not smoothly enter the pin hole  204   a  depending on a taper  204   t  of the pin hole  204   a  on the pod  200  side. 
         [0124]    A positioning member  500  of the fourth embodiment is provided with an outer casing  501  and an inner casing  502 . The outer casing  501  is a cylinder having a taper  501   a  formed on the tip, a brim  501   b  formed on the outside, a step  501   c  formed inside, a thread part  501   d  formed in the back of the brim  501   b , and the like, and is secured to the positioning plate  13 B using the brim  501   b.    
         [0125]    The inner casing  502  is a cylinder inserted into the outer casing  501  and has a taper  502   a  having the same angle as the taper  501   a  of the outer casing  501 , and a brim  502   b  formed on the outside of the end, wherein the brim  502   b  engages the step  501   c  to regulate the protrusion to a prescribed length. 
         [0126]    A spring  503  inserted in the inner casing  502  pushes the inner casing  502  in the protrusion direction. A box nut  504  thrust in a thread  501   d  of the outer casing  501  secures the outer casing  501  to the position adjusting plate  13 B and regulates the location of the end of the spring  503 . 
         [0127]    As shown in  FIG. 18(   a ), because the outer casing  501  and the inner casing  502  are provided with a taper  501   a  or  502   a  having the same angle which is more acute than the conventional angle and a length longer than a conventional one, these are smoothly linked even if the deviation is in the range of δ1=3.0−3.5 mm. 
         [0128]    As shown in  FIG. 18(   b ), because the inner casing  502  escapes resisting the pushing force of the spring  503  after the completion of linking, the depth of the pin hole  204   a  may be the same depth (L=11 mm) as the pin hole of the conventional pod  200 . 
       e. Fifth Embodiment 
       [0129]      FIGS. 19(   a ), ( b ), ( c ), and ( d ) show a positioning member for the table of the pod cover removing-installing apparatus according to a fifth embodiment. 
         [0130]    The positioning pins  15   a - 15   c  of the table  15  (see the table  105  of  FIG. 21 ) are arranged as shown in  FIG. 19(   b ). For this reason, when the table  15  moves in the direction of the arrow M, a force pushing up the pod  200  in the direction of the arrow N (N 1 ) is generated in the V-shaped grooves  205   a ,  205   c . However, no excessive force is produced by the V-shaped groove  205   c  which is parallel to the moving direction. 
         [0131]    As a result, a rotation force around the positioning pin  15   c  in the direction of the arrow P (P 1 ) is created in the pod  200  as shown in  FIG. 19(   d ). Because of this, the top end of the pod  200  may be separated from the partition board  11 , resulting in problems such as defective sealing. 
         [0132]    In the fifth embodiment, because the vertical fixed side  605   a - 1  ( 605   b - 1 ,  605   c - 1 ) provided in the V-shaped groove  605   a  ( 605   b ,  605   c ) formed on the bottom surface of the pod  600  enables the pod  600  to come into contact with the vertical fixed side  15   a - 1  ( 15   b - 1 ,  15   c - 1 ) of the positioning pin  15   a  ( 15   b ,  15   c ) (a bonding posture corrective means), no force pushing the pod  600  upward is created even if the container is pushed in the horizontal direction. 
         [0133]    A more detailed description is given of the pod  600  and the table  15  according to the fifth embodiment. 
         [0134]      FIGS. 22(   a ) and  22 ( b ) show the pod  600  and the table  15  according to the fifth embodiment of the present invention.  FIG. 22(   a ) is a partial sectional view taken along line A 1 -A 1  of  FIG. 22(   b ).  FIG. 22(   b ) is a bottom view. 
         [0135]      FIGS. 23(   a ) and  23 ( b ) are sectional views showing a V-section groove  605   a  and a positioning pin  15   a  according to the fifth embodiment, which are engaged with each other.  FIG. 23(   a ) is a sectional view taken along line A 2 -A 2  of  FIG. 22(   b ).  FIG. 23(   b ) is a sectional view taken along line B-B of  FIG. 22(   b ). It should be noted that  FIG. 23(   a ) similar to  FIG. 19(   a ) is shown for comparison. 
         [0136]    As shown in  FIG. 22(   b ), the pod  600  has three V-section groves  605   a ,  605   b  and  605   c.    
         [0137]    The V-section grooves  605   a  and  605   b  are arranged such that they depart from each other as they approach the cover  603  in a direction (arrow M) of the movement of the table  15 . In contrast, the V-section groove  605   c  is arranged such that its longitudinal direction is in parallel with the direction of the movement of the table  15 . 
         [0138]    A description is typically given of the V-section groove  605   a , omitting a description of the V-section grooves  605   b  and  605   c  which have a similar configuration. 
         [0139]    As shown in  FIGS. 23(   a ) and  23 ( b ), the V-section groove  605   a  includes an oblong hole (recessed portion)  605   a - 2  and a slope  605   a - 6 . 
         [0140]    The oblong hole  605   a - 2  is a recessed portion of the V-section groove  605   a  in a vertical direction (perpendicular to the horizontal direction of the movement of the table  15 ). As shown in  FIG. 22(   b ), the oblong hole  605   a - 2  has a parallel portion, and semicircular portions  605   a - 3  and  605   a - 4  at both ends of the oblong hole  605   a - 2 . 
         [0141]    As shown in  FIGS. 23(   a ) and  23 ( b ), the oblong hole  605   a - 2  has an inner wall serving as a fixed side  605   a - 1 , which comes into contact with a positioning pin  15   a.    
         [0142]    The slope  605   a - 6 , which starts from a bottom surface  605   a - 5  of the pod  600  and is provided around the thorough circumference of the oblong hole  605   a - 2 , tapers with a constant angle of inclination. 
         [0143]    As shown in  FIGS. 22(   a ) and  22 ( b ), the table  15  moves the pod  600  while it is placed on the table  15 . The table  15  is set to move in a horizontal direction. The table  15  has three positioning (linking) pins  15   a ,  15   b  and  15   c.    
         [0144]    The positioning pins  15   a ,  15   b  and  15   c  are arranged on the table  15  such that they are in geometrical conformity with the V-section grooves  605   a ,  605   b  and  605   c , respectively. The positioning pins  15   a ,  15   b  and  15   c  project from the table  15  such that their axes are vertically aligned with respect to the table  15 . A description is typically given of the positioning pin  15   a , omitting a description of the positioning pins  15   b  and  15   c , which have the similar configuration. 
         [0145]    As shown in  FIGS. 23(   a ) and  23 ( b ), the positioning pin  15   a  is a cylindrical member. The positioning pin  15   a , whose diameter is substantially the same as the width of the oblong hole  605   a , is engaged with the oblong hole  605   a . As shown in  FIG. 22(   b ), the diameter of the positioning pin  15   a  is substantially the same as those of the semicircular portions  605   a - 3  and  605   a - 4 , which are located at both ends of the oblong hole  605   a . In this way, it is possible to allow the positioning pin  15   a  to come into surface contact with the semicircles  605   a - 3  and  605   a - 4  so as to prevent damage to be imposed on them in case they collide with each other. 
         [0146]    As shown in  FIGS. 23(   a ) and  23 ( b ), a guide portion  15   a - 6  is provided around a thorough circumference in the vicinity of an end portion of the positioning pin  15   a . The guide portion  15   a - 6  is tapered as viewed in a cross section. The guide portion  15   a - 6  has an angle of inclination substantially the same as that of the slope  605   a - 6  of the V-section groove  605   a . Accordingly, it is possible to slide the slope  605   a - 6  of the V-section groove  605   a  on the guide portion  15   a - 6  so as to guide the fixed side  605   a - 1  to the positioning pin  15   a . In this way, it is possible to smoothly place the pod  600  on the table  15 . 
         [0147]    A description is next given of the operation of the pod  600  and the table  15 . 
         [0148]    As shown in  FIGS. 22(   a ) and  22 ( b ), an operator is allowed to place the pod  600  on the table  15  such that guide portions  15   a - 6 ,  15   b - 6  and  15   c - 6  of the positioning pins  15   a - 15   c  (see  FIGS. 23(   a ) and  23 ( b ) for  15   a - 6 ) and slopes  605   a - 6 ,  605   b - 6  and  605   c - 6  of the V-section grooves  605   a - 605   c  (see  FIGS. 23(   a ) and  23 ( b ) for  605   a - 6 ) come into contact with each other. Accordingly, the oblong holes  605   a - 2 ,  605   b - 2  and  605   c - 2  are guided to the positioning pins  15   a - 15   c , so that the fixed sides  605   a - 1 ,  605   b - 1  and  605   c - 1  of the V-section grooves  605   a - 605   c  and fixed sides  15   a - 1 ,  15   b - 1  and  15   c - 1  of the positioning pins  15   a - 15   c  eventually come into contact with each other. 
         [0149]    When the fixed side  15   a - 1  of the positioning pin  15   a  and the fixed side  605   a - 1  of the V-section groove  605   a  come in contact with each other (see  FIG. 22(   a )), and the fixed side  15   b - 1  of the positioning pin  15   b  and the fixed side  605   b - 1  of the V-section groove  605   b  come in contact with each other, the position of the pod  600  is determined in a back and forth direction, which corresponds to a direction of the movement of the table  15 . 
         [0150]    In addition, when the fixed side  15   c - 1  of the positioning pin  15   c  and the fixed side  605   c - 1  of the V-section groove  605   c  come into contact with each other, a rotational movement in a horizontal direction (see arrow θ in  FIG. 22(   b )) is restricted so as to perform positioning in the horizontal direction. 
         [0151]    As shown in  FIGS. 23(   a ) and  23 ( b ), with respect to a vertical direction, a flat surface  15   a - 7  provided on an end of the positioning pin  15   a  and a flat surface  605   a - 7  of the oblong hole  605   a  come into contact with each other. The same is true of a combination of the positioning pin  15   b  and the oblong hole  605   b - 2  and another combination of the positioning pin  15   c  and the oblong hole  605   c - 2 . In this way, the position of the pod  600  is determined in the vertical direction with respect to the table  15 . Since these flat surfaces in surface contact receive the load of the pod  600 , it is possible to prevent bottom surfaces  605   a - 5 ,  606   b - 5  and  605   c - 5  of the pod  600  from denting, increasing the durability of the pod  600 . 
         [0152]    When the cover  603  is removed or installed, the pod cover removing-installing apparatus can prevent the pod  600  from lifting as described above. When the diameter of a wafer increases, it is generally necessary to prepare a larger pod with a larger cover. This necessitates applying bigger force to the pod while the cover is removed or installed. Accordingly, it may be that the greater the diameter of wafer, the more likely the pod  600  tends to lift. 
         [0153]    Since the positioning pins  15   a - 15   c , which are oriented in the vertical direction perpendicular to the direction in which force is applied to the pad  600 , are in contact with the fixed sides  605   a - 1 ,  605   b - 1  and  605   c - 1 , respectively, the pod  600  according to this embodiment can efficiently prevent lifting described above. 
       f. Sixth Embodiment 
       [0154]      FIGS. 20(   a ) and ( b ) show a positioning member of the pod cover removing-installing apparatus according to a sixth embodiment. 
         [0155]    The fifth embodiment cannot be applied to a pod  200  which has already been used. Modification of the types and the like is necessary to change such a pod. For this reason, the sixth embodiment is provided with a binding posture corrective mechanism  700  which corrects the linking position of the pod  200 . 
         [0156]    The binding posture corrective mechanism  700  is provided with a rotor  701  such as a bearing provided on the top and side of the door frame  16  connected to the cover frame  207  of the pod  200  and maintaining contact with the cover frame  207 , a moving board  702  rotatively supporting the rotor  701  on the left end thereof and rotatively supported by the axis  702   a  at the upper right end, a linking member  705  which links the moving board  702  with a fixed board  703  so that the rotor  701  always presses the cover frame  207  with a spring  704  between them and regulates the counterclockwise rotation (arrow Q) of the moving board  702 , a regulating member  706  provided on the fixed board  703  to regulate the clockwise rotation (arrow R) of the moving board  702 , and the like. 
         [0157]    The rotor  701  can not only freely move in the moving direction (arrow M) on the table  15  by its rotation, but can also freely move in the right angle direction of the arrow M by the rotation of the moving board  702 . The rotor  701  is arranged so that it always presses the pod  200  by a spring  704 . In addition, the movable range for the rotor  701  is limited via a movable board  702  to the minimum push-out position of the linking member  705  and the maximum push-out position of the regulating member  706 . 
         [0158]    Therefore, the top and the side of the pod  200  can be pressed in the linked position so that the pod  200  is held in a normal posture ready to be linked. 
       g. Seventh Embodiment 
       [0159]      FIG. 24  is a sectional view showing a positioning pin  815   a  in contact with a V-section groove  605   a  of a pod  600  according to the seventh embodiment (see  FIG. 23(   a ) for comparison). 
         [0160]    In a cover removing-installing apparatus according to the seventh embodiment, the positioning pins  15   a - 15   c  according to the fifth embodiment are modified. 
         [0161]    A movable table  815  for removing and installing a cover according to the present embodiment has three position adjusting devices  810 .  FIG. 24  depicts one of these three. 
         [0162]    A position adjusting device  810  includes a base member  811 , a positioning pin  811 , a biasing member  816 , a bottom cover  817  and an optical sensor  818 . 
         [0163]    The base member  811  is a cylindrical member that supports the positioning pin  815   a  movably in an axial direction of the pin  815   a , namely in a vertical direction. The base member  811  has a guide portion  811 - 1  (a portion abutting with a slope of a V-section groove) that guides a fixed side  605   a - 1  to the positioning pin  815   a . The guide portion  811 - 1  has a circular cross section, which abuts with a slope  605   a - 6  of a V-section groove  605   a  so as to guide the fixed side  605   a - 1 . 
         [0164]    The guide portion  811 - 1  determines the vertical position (perpendicular to the movement of the table  815 ) of a pod  900 , while abutting with the slope  605   a - 6  of the V-section groove  605   a  after the guide portion  811 - 1  has guided the fixed side  605   a - 1  to the positioning pin  815   a.    
         [0165]    The base member  811 , which has threads  811 - 2  on its outer circumference, is attached to the table  815  with a nut  812 . 
         [0166]    The arrangement of positioning pins  815   a  is geometrically similar to that of the positioning pins  15   a - 15   c  according to the fifth embodiment. A positioning pin  815  is movably supported by the base member  811  in a vertical direction. The positioning pin  815   a  has a top portion like a hemisphere and a light shielding portion  815   a - 7  at a lower portion. 
         [0167]    When the positioning pin  815   a  projects from the base member  811 , a bottom surface of the light shielding portion  815   a - 7  is configured to be flush with a bottom surface of the bottom cover  817 . Accordingly, the light shielding portion  815   a - 7  projects with respect to the bottom cover  817  as shown with a two-dot chain line in  FIG. 24  while the positioning pin  815   a  is forced to retract into the base member  811 . 
         [0168]    A compressive coil spring installed in the base member  811  is an example of the biasing member  816 . The position of the biasing member  816  is determined in such a manner that the lowest portion of the biasing member  816  is supported by the bottom cover  817  and the highest portion abuts with an inner bottom surface of the positioning pin  815   a . In this way, the biasing member  816  biases the positioning pin  815   a  vertically upward, which allows the positioning pin  815   a  to project from the base member  811 . 
         [0169]    The bottom cover  817  is a member to engage with the base member  811  by threads so as to cover a lower portion of the base member  811 . The bottom cover  817  has a through hole that allows the light shielding portion  815   a - 7  to pass through. 
         [0170]    The optical sensor  818  is a detector that has a light emitting device  818 - 1  and a light receiving device  818 - 2 , which are disposed opposite to each other. The optical sensor  818  is disposed on the bottom surface of the bottom cover  817 . When the light shielding portion  815   a - 7  of the positioning pin  815   a  does not project from the bottom surface of the bottom cover  817 , the light receiving device  818 - 2  can receive light L emitted by the light emitting device  818 - 1 . In contrast, when the light shielding portion  815   a - 7  projects from the bottom surface of the bottom cover  817 , the light receiving device  818 - 2  cannot receive the light L, which is obstructed by the light shielding portion  815   a - 7 . In this way, the optical sensor  818  detects whether the light shielding portion  815   a - 7  projects from the bottom surface of the bottom cover  817 . 
         [0171]    The optical sensor  818  is electrically connected with the controller (see  FIG. 8 ), to which the optical sensor  818  transmits a detection signal. 
         [0172]    A description is given of operation of the pod  600  and the table  815 . 
         [0173]    When an operator places the pod  600  on the table  815 , the operator is merely requested to arrange the pod  600  such that the guide portion  811 - 1  abuts with the slope  605   a - 6  of the V-section groove  605   a . Accordingly, the oblong hole  605   a - 2  is guided to the positioning pin  815   a , so that the fixed side  605   a - 1  eventually comes into contact with the fixed side  815   a - 1  of the positioning pin  815   a.    
         [0174]    While the guide portion  811 - 1  is guiding the fixed side  605   a - 1  to the positioning pin  815   a , the positioning pin  815   a  is forced to retract into the base member  811 , because the slope  605   a - 6  of the V-section groove  605   a  thrusts the positioning pin  815   a.    
         [0175]    Accordingly, the light shielding portion  815   a - 7  of the positioning pin  815   a  projects from the bottom surface of the bottom cover  817 . The controller, which receives a signal from the optical sensor and determines that the pod  600  is not properly placed on the table  815 , maintains the table  815  at rest without activating the container moving motor (see  FIG. 8 ). 
         [0176]    When the guide portion  811 - 1  has guided the fixed side  605   a - 1 , the positioning pin  815   a  is biased by the biasing member  816  to project from the base member  811  (see  FIG. 24 ). The horizontal position of the pod  600  with respect to the table  815  is determined by the positioning pin  815   a.    
         [0177]    In parallel, the vertical position of the pod  600  is determined by the guide portion  811 - 1  that abuts with the slope  605   a - 6  of the V-section groove  605   a.    
         [0178]    Under this situation, the bottom surface of the light shielding portion  815   a - 7  of the positioning pin  815   a  moves upward to be flush with the bottom surface of the bottom cover  817 . Accordingly, since the controller determines that the pod  600  has been properly placed on the table  815 , receiving a signal from the optical sensor  818 , it activates the container moving motor so as to advance the table  815 . 
         [0179]    In this connection, it may be possible to determine whether the pod  600  is properly placed on the table  815  by the following alternatives. 
         [0180]    An alternative introduces an optical sensor that is provided on the table  815  to measure the distance between the top surface of the table  815  and the bottom surface of the pod  600  so as to check the correct placement of the pod  600 . For this purpose, it is necessary for the optical sensor to maintain the accuracy substantially within 2 mm, which may be disadvantageous in terms of required accuracy for installation and maintenance. 
         [0181]    Another alternative introduces a sensor to detect the weight of the pod  600 , such as a pressure sensor, which is attached to the positioning pins  815   a - 815   c  so as to check the placement of the pod  600 . This method has disadvantages as follows: Since the pressure sensor has relatively large detection error, it may be a cause for the malfunction of the table  815 . In addition, the weight of the pod  600  has variations according to objects contained in the pod  600 . 
         [0182]    In contrast, the above-mentioned embodiment of the present invention, which determines whether the positioning pin  815   a  projects from the bottom cover  817  so as to check whether the pod  600  is properly placed on the table  815 , is almost immune to a detection error. In addition, it is possible to maintain a movement stroke of the positioning pin  815   a  to be substantially the same as the depth of the oblong hole  605   a - 1 . This indicates that since it is possible to select a greater value, ex. 5 mm for the movement stroke corresponding to the amount of projection of the positioning pin  815   a , this embodiment does not require high accuracy for installation, realizing easy maintenance. 
         [0183]      FIG. 25  is a sectional view showing a positioning pin  815   a  of the cover removing-installing apparatus engaging with a V-section groove  205   a  of a pod  200  according to the seventh embodiment (see  FIG. 23(   a ) for comparison). 
         [0184]    The conventional pod  200  does not have oblong holes  605   a - 2 ,  605   b - 2  and  605   c - 2  (see  FIG. 22(   b )), which are introduced into the pod  600  according to the present invention. However in the case of the conventional pod  200 , a slope  205   a - 6  of the V-section groove  205   a  thrusts the positioning pin  815   a  to retract into the base member  811 . Since the guide portion  811 - 1  (a portion abutting with a slope of a V-section groove) abuts with the slope  205   a - 6  of the V-section groove  205   a  accordingly, the horizontal and vertical directions of the pod  200  can be determined. 
         [0185]    It should be noted that the controller controls the movement of the table  815  regardless of reception of a signal from the optical sensor  818 . 
         [0186]    In this way, it is possible to apply the cover removing-installing apparatus according to the present embodiment to a conventional pod  200 . 
         [0187]    As described above, determining whether the pod  600  is properly placed on the table  815 , the cover removing-installing apparatus according to the seventh embodiment can safely advance the table  815 . 
         [0188]    In addition, the cover removing-installing apparatus according to the seventh embodiment can be applied to both the pod  600  that has the oblong holes  605   a - 2 ,  605   b - 2  and  605   c - 2  and the conventional pod  200  without these oblong holes. 
       h. Eighth Embodiment 
       [0189]      FIG. 26  is a sectional view showing a positioning pin  915   a  engaging with a V-section groove  605   a  of a pod  600  (see  FIG. 23(   a ) for comparison). 
         [0190]    Three positioning pins  915   a  are disposed on a table  915  of a cover removing-installing apparatus similarly with the positioning pins  15   a - 15   c  of the fifth embodiment. 
         [0191]    A positioning pin  915   a  has a two-part configuration, an upper portion  915   a - 7  and a lower portion  915   a - 8 . A guide portion  915   a - 6  is provided on an end portion of the upper portion  915   a - 7 . The guide portion  915   a - 6  having a circular cross section abuts with a slope  605   a - 6  of the V-section groove  605   a  so as to guide a fixed side  605   a - 1  of the V-section groove  605   a  to a fixed side  915   a - 1  of the fixed pin  915   a . In addition, a cross section of the lower portion  915   a - 8  (a portion abutting with a slope of a V-section groove) is circular. 
         [0192]    When the fixed side  915   a - 1  of the positioning pin  915   a  and the fixed side  605   a - 1  of the V-section groove  605   a  are in contact with each other, the position of the pod  600  is determined with respect to the table  915  in the similar manner to the seventh embodiment. 
         [0193]    The horizontal position of the pod  600  is determined by the fixed side  915   a - 1  of the positioning pin  915   a  and the fixed side  605   a - 1  of the oblong hole  605   a - 2 . Similarly, the vertical position of the pod  600  is determined by the lower portion  915   a - 8  of the positioning pin  915   a  and the slope  605   a - 6  of the V-section groove  605   a , which abut with each other. 
         [0194]    As described above, the cover removing-installing apparatus according to the present embodiment can determine the position of the pod  600  with the positioning pin  915   a  whose top surface is not flat but circular. 
       i. Ninth Embodiment 
       [0195]      FIG. 27  is a sectional view showing a positioning pin  1015   a  engaging with a V-section groove  605   a  of a pod  600  (see  FIG. 23(   a ) for comparison). 
         [0196]    The positioning pin  1015   a  has a detection pin  1015   a - 8  that is vertically movable. The positioning pin  1015   a  includes a biasing member  1016  and an optical sensor  1018 , which are similar to the biasing member  816  and the optical sensor  818  of the seventh embodiment, respectively. 
         [0197]    The positioning pin  1015   a  is biased vertically upward by the biasing member  1016 . When a pod  600  is not placed on a table  1015 , the detection pin  1015   a - 8  projects with respect to a flat portion  1015   a - 7  as shown by a two-dot chain line in  FIG. 27  and the bottom surface of a light shielding portion  1015   a - 9  is adjusted to be in flush with the bottom surface of a bottom cover  1017 . 
         [0198]    When the pod  600  is placed on the table  1015  and a fixed side  605   a - 1  is guided by a guide portion  1015   a - 6 , the pod  600  is properly placed on the table  1015 . Accordingly, the flat portion  1015   a - 7  of the positioning pin  1015   a  comes into surface contact with a flat surface  605   a - 7  of the bottom portion of the pod  600 . Under this configuration, the flat surface  605   a - 7  thrusts the detection pin  1015   a - 8  vertically downward. Accordingly as shown in  FIG. 27 , the detection pin  1015   a - 8  is depressed into the inside of the positioning pin  1015   a . Since the light shielding portion  1015   a - 9  simultaneously projects from the bottom cover  1017   a , a light receiving device  1018 - 2  cannot receive light L emitted by a light emitting device  1018 - 1 . In this way, the pod cover removing-installing apparatus according to the embodiment can detect whether the pod  600  has been properly placed on the table  1015 . 
         [0199]    As described above, receiving a signal from a detector with the light emitting device  1018 - 1  and the light receiving device  1018 - 2 , the cover removing-installing apparatus according to the embodiment can detect whether the flat portion  1015   a - 7  of the positioning pin  1015   a  has come into surface contact with the flat surface  605   a - 7  of the bottom portion of the pod  600 . Accordingly, the cover removing-installing apparatus can detect whether the pod  600  has been properly placed on the table  1015 . 
         [0200]    It should be noted that the cover removing-installing apparatus can alternatively employ a pressure sensor that is provided on the flat surface  1015   a - 7  of the positioning pin  1015   a  in lieu of the light emitting device  1018 - 1  and the light receiving device  1018 - 2 . In this case, the cover removing-installing apparatus determines whether the pod  600  is placed on the table  1015  based on a change in pressure that results from the surface contact between the flat portion  1015   a - 7  of the positioning pin  1015   a  and the flat surface  605   a - 7  of the pod  600 . In this way, the cover removing-installing apparatus can provide more confident detection whether the pod  600  has been properly placed on the table  1015 . 
       j. Modification 
       [0201]    The present invention is not limited to the above-described embodiments and can be varied or modified in various ways. Such variations and modifications are within the scope of equivalency of the present invention. 
         [0202]    For example, although the cover securing means was described in  FIG. 7  using a stretch member  63  by way of example, a modified type having a broken part in the positioning pin  14   a  ( 14   b ) to mechanically change the diameter of the positioning pin  14   a  ( 14   b ) can be used for securing the pins in the pin holes. 
         [0203]    Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.