Abstract:
A transport system for transporting transport containers storing articles in a sealed condition is disclosed. Each transport container has a support portion formed on an upper portion thereof. When the transport container is moved with the support portion suspended, a receiving device supports the bottom of the transport container to lessen the load applied to the support portion. As a result, deformation of the transport container is restrained to maintained the sealed condition.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to a transport system having a lift device for raising and lowering articles, and a moving body for moving the lift device.  
           [0003]    More particularly, a transport container to be transported includes a main container body defining an opening for storing articles and having a support portion formed on an upper surface of the container body for suspending the container body, and a lid for closing the opening of the main container body. When the opening is closed by the lid, the interior space of the main container body is sealed. The invention relates to a transport system having a lift device for raising and lowering the transport container while suspending the transport container by holding the support portion thereof, and a moving body for moving the lift device.  
           [0004]    2. Description of the Related Art  
           [0005]    In the transport system having the above construction, articles such as semiconductor substrates that are vulnerable to dust are received in transport containers and transported free from adverse effects of dust. This transport system is used in manufacturing equipment for successively transporting the transport containers to a plurality of processing apparatus that perform various manufacturing processes to manufacture semiconductor substrates or the like. In such manufacturing equipment, the transport containers are placed on receiving surfaces in article loading and unloading stations of the above processing apparatus. When transporting the transport containers, the main container bodies are suspended by the support portions formed on the upper surfaces thereof, raised and lowered, and transported horizontally as necessary.  
           [0006]    In such a transport system, conventionally, when transporting the transport containers, each container is suspended by the support portion formed on the upper surface of the main container body continuously from start till end of the transport (see to Japanese Patent Publication (Unexamined) H9-77455).  
           [0007]    In the above conventional construction, the transport container may, for example, vibrate up and down during transport. However, since the transport container is supported as gripped and suspended by the support portion formed on the upper surface, the vertical vibration occurring in time of transport causes a dynamic load of articles stored in the main container body. As a result, the transport container is deformed to enlarge the capacity of interior space of the main container body, whereby ambient air could enter the interior space of the main container body through sealed portions between the lid and the main container body. The transport container for storing articles such as semiconductor substrates are often formed of plastic. Such main container body formed of plastic is deformable by the vertical vibration occurring in time of transport, to enlarge the capacity of interior space of the main container body and allow entry of ambient air. Thus, the articles may undergo adverse effects such as lowering of quality.  
         SUMMARY OF THE INVENTION  
         [0008]    This invention has been made having regard to the state of the art noted above, and its object is to provide a transport system for avoiding entry of ambient air to an interior space of a transport container during transport.  
           [0009]    According to this invention, the receiving device is switched to the holding position when transporting the transport container. As a result, the receiving device receives the bottom of the transport container suspended from the lift device, and bears the weight of the transport container. This lessens, or reduces to zero, the force of support for the support portion by the lift device. Then, even when the transport container vibrates vertically during transport, for example, little or no deformation of the main container body is allowed, thereby avoiding entry of ambient air to the interior space of the main container body.  
           [0010]    Thus, the transport system provided by this invention is effective to avoid ambient air entering the transport container in time of transport. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a plan view showing an entire transport system;  
         [0012]    [0012]FIG. 2 is a perspective view showing a central portion of the transport system according to this invention;  
         [0013]    [0013]FIG. 3 is a view showing a transport container;  
         [0014]    [0014]FIG. 4 is a side view showing a state of transport;  
         [0015]    [0015]FIG. 5 is a side view showing a construction according to this invention;  
         [0016]    [0016]FIG. 6 is a plan view showing a lift mechanism;  
         [0017]    [0017]FIG. 7 is a front view in vertical section showing a construction of a carrier vehicle;  
         [0018]    [0018]FIG. 8 is a plan view showing a construction of a receiving device;  
         [0019]    FIGS.  9 (A) and  9 (B) are front views showing two states of the receiving device; and  
         [0020]    FIGS.  10 (A) and  10 (B) are side views showing a receiving device in another embodiment.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    A transport system according to this invention will be described hereinafter with reference to the drawings.  
         [0022]    [0022]FIG. 1 shows a portion of manufacturing equipment for manufacturing semiconductor substrates. This equipment is installed in a cleaned indoor space with little dust. The equipment includes a plurality of article processing apparatus A for performing predetermined treatment of half-finished semiconductor substrates in the course of manufacture, and a transport system B for transporting the substrates to container receiving stations H of these article processing apparatus A. The article processing apparatus A are arranged along a direction of article transport (as indicated by an arrow) by the transport system B. As seen from FIG. 1, one row of article processing apparatus A is opposed to a different row of article processing apparatus A. As is well known, and therefore not particularly described herein, these article processing apparatus A successively perform plural types of chemical treatment to manufacture semiconductor substrates.  
         [0023]    Next, the construction of transport system B will be described with reference to FIGS. 1 and 2. Semiconductor substrates  1  to be treated are stored in a set number in each transport container  2 . The transport container  2  is transported to the container receiving station H of each of the plurality of article processing apparatus A. A container receiving table  3  is disposed at the container receiving station H of each article processing apparatus A. In this transport system, the transport container  2  is placed on the container receiving table  3 .  
         [0024]    Each transport container  2  is formed of plastic and, as shown in FIG. 3, includes a main container body  2   a  having an opening  4  formed in one side for receiving semiconductor substrates  1 , and a lid  2   b  for closing the opening  4  in a sealed state. The main container body  2   a  has, formed on an upper surface thereof, a flange  5  acting as a support portion to be suspended by a gripper described hereinafter. This transport container  2  has an interior space of main container body  2   a  sealed to admit substantially no entry of dust-laden ambient air through gaps.  
         [0025]    Next, a device for transporting such transport containers  2  will be described. As shown in FIG. 4, carrier vehicles  8  run along a guide rail  7  fixed by brackets  6  to a ceiling. Each carrier vehicle  8  includes a vehicle member  8 A disposed in an inner space of the guide rail  7  to act as one example of moving body, and a transport action unit  8 B connected to the vehicle member  8 A and disposed below the guide rail  7 . The vehicle member  8 A is driven by a linear motor that generates propelling drive, to run along the guide rail  7 . The transport action unit  8 B is connected by front and rear connecting bars  9  and  10  to the vehicle member  8 A. As seen from a section of the guide rail  7  shown in FIG. 7, the guide rail  7  has a pair of right and left legs extending generally vertically and spaced from each other. The inner space is formed between these right and left legs. The legs have guide surfaces  14  formed at lower ends thereof for supporting running wheels  13  of the carrier vehicle  8 . In addition, the legs define vibration damping guide surfaces  16  for contacting vibration damping wheels  15 .  
         [0026]    The vehicle member  8 A derives drive from a linear motor LM for driving the carrier vehicle  8 . As shown in FIG. 7, the linear motor LM includes a magnet  11  mounted in the inner space of the guide rail  7 , and a primary coil  12  mounted on the carrier vehicle  8  to be adjacent and opposed to the magnet  11 . In FIG. 7, numeral  17  denotes power supply lines attached to the guide rail  7 , and number  18  denotes power receiver coils attached to the carrier vehicle  8 . A supply of AC forms magnetic fields around the power supply lines  17 , which in turn generate power on the receiver coils  18  as required by the carrier vehicle  8 . In this way, power is supplied in a non-contact mode.  
         [0027]    The transport action unit  8 B has a frame  19  connected to the vehicle member  8 A by the front and rear connecting bars  9  and  10 . The frame  19  supports a lift control unit  20  for gripping the flange  5  and raising and lowering the transport container  2  as supported in suspension. Further, the transport action unit  8 B includes a holder  21  acting as a receiving device switchable between a holding position for receiving and supporting the bottom  2   c  of the transport container  2  suspended by the lift control unit  20  and bearing the weight of the transport container  2 , and a position retracted from the bottom  2   c  of the transport container  2 .  
         [0028]    More particularly, the lift control unit  20  includes a lift member  23  vertically movable relative to the vehicle member  8 A, and a gripper  22  supported by the lift member  23  and switchable between an operative position for gripping the flange  5  of the transport container  2  and a release position for releasing the flange  5 . The lift member  23  is vertically movable by a lift control mechanism  24  attached to the frame  19 . These lift control unit  20  and lift control mechanism  24  constitute the lift device. As shown in FIGS. 6 and 7, the lift control mechanism  24  has a rotating drum  25  rotatable about a vertical axis by a drum drive motor M 1 . This rotating drum  25  has a construction to wind and unwind four wires  26  simultaneously. With forward and backward rotations of the rotating drum  25 , the lift member  23  supported by the four wires  26  are moved vertically while being maintained in a substantially horizontal posture. The lift control mechanism  24  does not necessarily require such rotating drum  25 , but may have a construction for winding and unwinding the respective wires  26  with separate motors.  
         [0029]    As shown in FIGS. 5 and 7, the gripper  22  is switchable between a gripping position for gripping the flange  5  with a gripper actuating motor M 2  swinging a pair of gripping members  28  toward each other through a link mechanism  27 , and a release position for releasing the flange  5  by swinging the gripping members  28  away from each other. Further, the gripper  22  is attached to the lift member  23  to be rotatable about a vertical axis by a motor M 3 .  
         [0030]    The holder  21  has a pair of vertical frame portions  29  depending from the frame  19  and arranged forward and rearward with respect to the direction of movement of the vehicle member. Each vertical frame portion  29  has a pair of receiving members  30  attached to the lower end thereof. Each receiving member  30  is switchable between a projecting position for receiving and supporting the bottom  2   c  the transport container  2  raised by the lift control unit  20 , and a retracted position out of a lifting path for allowing the lift control unit  20  to raise and lower the transport container  2 .  
         [0031]    As shown in FIGS. 8 and 9, each receiving member  30  has one end thereof located in a recess  31  formed in one of the vertical frame portions  29 , and is supported by a vertical support shaft  32  to be pivotable about a vertical axis. The support shaft  32  is rotatable by an electric motor M 4  with a reduction gear, through a link mechanism not shown, whereby a free end of the receiving member  30  is switched between a position projecting to the lifting path of the transport container  2 , and a position retracted into the recess  31 . The receiving member  30 , with the one end thereof located in the recess  31  formed in the vertical frame portion  29  as noted above, is restrained from vertical displacement by upper and lower inner surfaces of the recess  31 . Consequently, the receiving member  30  can receive the transport container  2  even though its load falls on the free end projecting in cantilever fashion.  
         [0032]    Numeral  33  in FIG. 7 denotes a controller for controlling movement of the carrier vehicle  8  and operation of the transport action unit  8 B in response to instructions from a supervising controller on the ground and to detection information received from sensors or the like, though not particularly described herein, mounted on the carriers  8 .  
         [0033]    A transporting operation of the transport system having the above construction will be described next. In this operation, each transport container  2  is transported from a transport starting point (i.e. one container receiving station H) to a transport target point (another container receiving station H). Operations of the holder  21  and lift control unit  20  are controlled by the controller  33 . As shown in FIG. 4, the carrier vehicle  8  is moved to a position corresponding to the transport starting point, where the lift control unit  20  is lowered. The gripper  22  grips the flange  5  of the transport container  2  placed in the container receiving station H. The transport container  2  is raised to a level close to the carrier vehicle  8 . At this time, the lift control unit  20  raises the transport container  2  to an upper limit. As the carrier vehicle  8  begins to move toward the transport target point, the holder  21  is switched from the retracted position to the holding position. Specifically, the receiving members  30  are switched to the projecting positions, respectively. Thereafter, the lift control unit  20  is lowered by a set amount. When the lift control unit  20  is lowered by the set amount, the bottom  2   c  of the transport container  2  is received and stopped by the receiving members  30 . The flange  5  is thereby slightly elevated relative to the gripper  22 , thereby reducing the force of support for the flange  5  by the lift control unit  20  to zero. When the receiving members  30  are switched to the projecting positions, respectively, the transport container  2  has been raised to the upper limit with the receiving members  30  lying slightly below the bottom  2   c  of the transport container  2 . Thus, the receiving members  30  may easily be switched to the projecting positions.  
         [0034]    The carrier vehicle  8  moves along the guide rail  7  with the weight of the transport container  2  borne by the receiving members  30  as described above. Thus, there is little chance of the transport container  2  being deformed by vibration occurring during the movement of the carrier vehicle  8 , to allow entry of ambient air to its interior.  
         [0035]    When the carrier vehicle  8  arrives at the position corresponding to the transport target point, the carrier vehicle  8  is stopped, and then the lift control unit  20  is raised to raise the transport container  2  by the set amount with the gripper  22  gripping the flange  5 . While the bottom  2   c  of the transport container  2  is raised above the receiving members  30 , the receiving members  30   s  are switched from the projecting positions to the retracted positions. Subsequently, the lift control unit  20  is lowered with the gripper  22  gripping the flange  5 , to place the transport container  2  in the container receiving station H. Then the gripper  22  releases the flange  5  to complete the transporting operation.  
         [0036]    Modified Embodiments are Set Out Below  
         [0037]    (1) In the foregoing embodiment, the operation for switching the holder  21  from the retracted position to the holding position is carried out when the carrier vehicle  8  begins to move toward the transport target point after the transport container  2  is raised close to the carrier vehicle  8 . Instead, the switching operation may be carried out as soon as the transport container  2  is raised close to the carrier vehicle  8 . In the foregoing embodiment, the operation for switching the holder  21  from the holding position to the retracted position is carried out after the carrier vehicle  8  arrives and stops at the position corresponding to the transport target point. Instead, this switching operation may be carried out a short time before the carrier vehicle  8  stops.  
         [0038]    (2) In the foregoing embodiment, when the holder  21  is switched to the holding position, the force of support for the flange  5  by the lift control unit  20  is reduced to zero. Instead, the force of support for the flange  5  by the lift control unit  20  may be reduced to a smaller value than when the lift control unit  20  bears the total weight of the transport container  2 .  
         [0039]    (3) In the foregoing embodiment, the receiving device  21  is mounted on the frame  19  connected to the vehicle member  8 A. Instead, the receiving device  21  may be mounted on the lift member  23  of lift control unit  20  in the foregoing embodiment. As shown in FIG. 10, for example, a lift member  23  raised and lowered by a lift control mechanism  24  having the same construction as in the foregoing embodiment may have a pair of receiving members  40  pivotable about horizontal axes by a drive mechanism including an electric motor and a link mechanism. When the receiving members  40  are switched to a holding position immediately after the transport container  2  is gripped and raised slightly, the holding action of the receiving members  40  slightly elevates the transport container  2  to raise the flange  5  slightly above the gripper  22  (see FIG. 10(A)). Then, the vehicle member  8 A is moved with the transport container  2  received and raised by the receiving members  40 . This construction is effective to avoid entry of unclean ambient air to the container not only during movement of the vehicle member  8 A but also when the transport container  2  is raised.  
         [0040]    (4) In the foregoing embodiment, the gripper is constructed switchable between the gripping position for gripping the flange by swinging the gripping members, and the release position for releasing the flange by swinging the gripping members away from each other. This construction is not limitative, but may be modified in various ways. For example, the gripping members may be adapted pivotable about vertical axes, or otherwise movable horizontally, to switch between a position for gripping the flange and a position for releasing the flange. The specific construction of the receiving device similarly is not limited to the switching through pivotal movement about the vertical axes as in the foregoing embodiment or to switching through pivotal movement about horizontal axes toward and away from each other, but may be modified in various ways, such as switching by horizontal movement.  
         [0041]    (5) In the foregoing embodiment, each moving body is in the form of a vehicle member for running along the guide rail. Instead, it is possible to use linear motor cars which run along the guide rail but have no wheels. Other modifications include use of articulated transport robots.  
         [0042]    (6) The foregoing embodiment has been described as having a construction for supplying power to each vehicle member  8 A in a non-contact mode. However, this is not limitative, but a contact type power supply may be provided in which a conductor mounted on each vehicle member contacts a power supply rail. Instead of the non-contact type or contact type power supply each vehicle member may carry a storage device such as a battery or capacitor. Each vehicle member may carry a storage device, and yet receive a non-contact type or contact type power supply when appropriate. Then, the storage device may supply power when, for example, no external power supply is available in the contact or no-contact mode.