Abstract:
A work conveying system eliminates gravitational deflection of an extended articulated arm of a vertical mover. The conveying system includes a horizontal mover which carries the vertical mover and a work holder for delivering a workpiece to various apparatuses without dislocation. In conveying a workpiece horizontally, the vertical mover folds compactly to minimize air disturbance. Plural arm elements of the articulated arm overlap and are connected together in an alternate manner at their respective end portions, and the articulated arm is extended and contracted by pivotal movement of the arm elements, driven by a single drive unit. The horizontal mover is movable in an arbitrary horizontal plane within the upper ceiling space within the clean room. Shafts in the articulated arm and a rotary drive unit in the work holder have hollow interiors which are intercommunicated and at a negative pressure.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a work conveying system for a clean room and more particularly to a work conveying system which conveys a workpiece to various processing stations in a production line within a clean room for the production of, for example, semiconductor components, liquid crystal display panels, medical supplies, chemicals, and processed foods. 
     2. Description of the Prior Art 
     In manufacture of a semiconductor integrated circuit or a liquid crystal display panel, deposition of dust must be avoided. It is desirable that medical supplies, chemicals, and processed foods be produced in a sterile hygienic environment. Therefore, in a wide variety of fields, intra-clean room production lines are utilized. 
     The present applicant has previously invented a work conveying system (see Japanese Patent Laid Open No. 2000-243808), which system is provided with drive means able to arbitrarily move a work holding means in three dimensions in an upper ceiling space within a clean room. In this work conveying system, a pair of horizontal fixed guide rails are laid in parallel in the ceiling space and one or plural horizontal traveling guide rails are mounted between the paired fixed guide rails for travel along the fixed guide rails. Also, a travel body is mounted for travel along the traveling guide rail(s), and a horizontal moving means is provided by the combination of the fixed guide rails, the traveling guide rail(s) and the travel body. Further, the travel body is provided with a vertical moving means for raising and lowering the work holding means. Thus, three-dimensional movement/conveyance is provided by the combination of the vertical moving means and the horizontal moving means. 
     FIGS.  10 (A),  10 (B),  11 (A) and  11 (B) show such a vertical moving means  013 , in which FIG.  10 (A) is a front view showing a raised state of the vertical moving means, FIG.  10 (B) is a side view in vertical section, FIG.  11 (A) is a front view showing a lowered state thereof, and FIG.  11 (B) is a side view in vertical section. As shown in these figures, the vertical moving means  013  is an articulated arm having three arm elements  016 - 018 . With pivotal movements of a first start-end arm element  016 , a second arm element  017 , and a third (terminal-end) arm element  018 , a work holding means  011  fixed to the third (terminal-end) arm element  018  is moved up and down on a vertical line. The work holding means  011  delivers a workpiece (e.g., a hermetically sealed container) to each of various processing apparatuses. As shown in FIGS.  10 (B) and  11 (B), the articulated arm has the arm elements  016 - 018  stacked in multiple stages. 
     The pivotal movements of the arm elements  016 - 018  are respectively driven by a motor  021   a  disposed within a body  015 , a motor  021   b  disposed within the first start-end arm element  016 , and a motor  021   c  disposed within the second arm element  017 . Though not shown in detail, the interiors of the arm elements  016 - 018  and the interior of the body  015  are in communication and are under a negative pressure so that dust generated in those interiors is removed in one direction. 
     With the above-described work conveying system, an area for work conveyance is not required on the floor surface of the clean room and the interior of the clean room can be more effectively utilized. Therefore, for the same equipment, the space required in the clean room can be reduced and it is possible to reduce the equipment cost and operation cost of the clean room. Moreover, the location and orientation of apparatus such as processing chambers installed within the clean room are not restricted and it is possible to select an optimal arrangement. Also in the case of adding a new apparatus such as a processing chamber or in the case of changing the arrangement of items such as processing chambers, it is possible to freely select their arrangement and orientation. Thus, it is also possible to reduce the cost of changing arrangement of or increasing the number of items of apparatus such as processing chambers. Further, it is possible to move the work holding means  011  linearly from one position to another position, whereby the work efficiency in the clean room is improved. 
     However, in the above-described work conveying system, a torque load based on arm weight is imposed on the mounting portion for mounting to the horizontal moving means and deflection caused by extension of the articulated arm is significant. Further, in the articulated arm of this structure, the pivotal movement of the first start-end arm element  016  relative to the horizontal moving means is performed by operation of a motor  021   a  provided on the horizontal moving means (travel body  015 ) side and thus this structure is difficult to seal. In addition, motors  021   a - 021   c  are used as dedicated drive sources for pivotal movements of the first to third arm elements  016 - 018 , respectively, and such multiple drive sources are apt to generate dust. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to solve the above-mentioned problems of the conventional work conveying system and to provide a work conveying system which eliminates gravitational deflection induced upon extension of the articulated arm in the vertical moving means, permits the work holding means to deliver a workpiece to each processing apparatus without dislocation, permits smooth extension and contraction of the articulated arm, permits the vertical moving means to be folded compactly when conveying a workpiece horizontally, thereby minimizing the disturbance of air flow, and which is easily sealed. 
     It is another object of the present invention to provide a work conveying system which, in the case of workpieces in the form of wafers or reticles, can convey the wafers or reticles each individually and rapidly to a predetermined processing apparatus and can thereby improve the working efficiency. 
     For solving the foregoing problems, in one aspect of the present invention, there is provided a work conveying system comprising a work holding means for holding a workpiece, a horizontal moving means for moving the work holding means horizontally in an upper ceiling space within a clean room, and a vertical moving means provided in the horizontal moving means and formed as an articulated arm, the articulated arm being adapted to extend and contract, thereby causing the work holding means to move up and down, the workpiece thereby being conveyed to the plural items of apparatus while circulating among the processing stations within the clean room, wherein plural arm elements of the articulated arm are overlapped and connected together at alternating end portions, and the articulated arm is extended and contracted with pivotal movements of the arm elements. 
     With the above-described first aspect of the invention there is no fear of centroid deviation of the articulated arm and the weight balance of the entire arm is stable, with little gravitational deflection, even upon extension (descent of the vertical moving means). Consequently, it becomes possible for the work holding means to deliver a workpiece to each of various processing apparatuses without dislocation, the extension and contraction of the articulated arm being performed smoothly, and when conveying a work horizontally, the vertical moving means can be folded compactly to minimize the disturbance of air flow. Further, there is no torque based on the weight of the entire arm and the workpiece weight, thus permitting stable conveyance of a workpiece horizontally. 
     In a second aspect the present invention provides a work conveying system comprising work holding means for holding a workpiece, horizontal moving means for moving the work holding means horizontally and located in an upper ceiling space within a clean room, and an articulated arm, serving as vertical moving means and provided on the horizontal moving means. The articulated arm extends and contracts to thereby cause the work holding means to move up and down, allowing the work to be transferred between the work holding means and each of plural items of processing apparatus, while the workpiece is circulated among the different items of processing apparatus within the clean room. The articulated arm has three or more arm elements, a single drive, and a predetermined pivoting ratio among the arm elements. The articulated arm is extended and contracted linearly by operation of the drive source and consequent pivotal movements of the arm elements, so that by a combined use of a single drive source and three or more arm elements which are interlocked with one another, smooth motion free of impact is ensured. 
     A third aspect of the present invention provides, in combination with the above-described first aspect, a work conveying system wherein the vertical drive means, constituted by an articulated arm having three or more arm elements, has a single drive source and a predetermined pivoting ratio among the arm elements, and the articulated arm is extended and contracted by operation of the drive source and by consequent pivotal movements of the arm elements. By a combined use of a single drive source and three or more arm elements that are interlocked with one another, there is obtained a smooth impact-free motion. 
     In a fourth aspect the present invention provides, in combination with the above-described first or second aspect, mounting of the horizontal moving means in the upper ceiling space within the clean room for movement in an arbitrary horizontal plane. The work holding means is also movable in an arbitrary horizontal plane in the upper ceiling space within the clean room, so that the location and orientation of items of processing apparatus, such as processing chambers installed within the clean room, are not restricted and it is possible to select an optimal arrangement. Moreover, also in the case of adding a new item of apparatus, such as a new processing chamber, or in the case of changing the arrangement of the apparatus, it is possible to freely select their arrangement and orientation and hence the cost for changing the arrangement of or adding to the apparatus is reduced. Further, it is possible to move the work holding means linearly from one position to another position and therefore the work processing efficiency within the clean room is improved. 
     In a fifth aspect the present invention provides, in combination with the above second aspect, pivotal movement of a first start-end arm of the vertical moving means, relative to the horizontal moving means, is driven by a motor disposed on the first arm element. This construction provides for sealing of dust generated from a single drive source (the motor) and the dust generated from the pivoting structure, all on the arm side. Further, by utilizing an empty space, i.e. the internal space within the first arm element, it is possible to accommodate the motor which serves as the sole drive source, thus affording a work conveying system of a compact structure. 
     In a sixth aspect the present invention provides, in combination with the above first or second aspect, a work conveying system wherein the arm elements of the articulated arm are hollow and the internal spaces within the arm elements are intercommunicated and evacuated to a negative pressure. With this structure discharge of generated dust from the internal space of each of the arm elements is simplified, the amount of dust leaking into the clean room is greatly decreased, and it becomes easy to maintain the clean room at a required degree of cleanliness. 
     In a seventh aspect the present invention provides, in combination with the above first or second aspect, a work conveying system wherein the work holding means is provided with a work rotation drive unit so that the work can be rotated in a horizontal plane. This work rotation drive unit, in addition to facilitating conveyance of the work in three dimensions, provides a rotational direction/posture control for the work in a horizontal plane and accurate rotational positioning in loading the work, thus fulfilling requirements for high degree of accuracy in a work conveying system. 
     The present invention may also include a hermetically sealed work container held by the work holding means. Plural wafers or reticles may be accommodated in the hermetically sealed work container and in this state can be conveyed within the clean room, so that it is possible to easily attain the high-degree of cleanliness required for such workpieces. 
     Alternatively, the work holding means may hold a single workpiece, such as a wafer or a reticle, directly. 
     Further, the directly held workpiece may bear an identification mark indicating the processing steps to which the workpiece is to be subjected. In this case the apparatus of the present invention further includes a detector for reading the identification mark. In directly holding a single workpiece, the detector on the work holding means reads the identification mark and transmits a signal to a controller in the work conveying system, whereby the work conveying system can convey the workpiece rapidly to each processing apparatus in a predetermined sequence for predetermined working, within the three-dimensional space of a clean room. Consequently, the working efficiency of the work conveying system is improved to a remarkable extent. 
     Alternatively, the detector for detecting identification marks on workpieces may be disposed at a fixed position within the clean room. The detector reads the identification mark affixed to the workpiece upon arrival of the workpiece at the installed position of the detector and then transmits a signal to a controller in the work conveying system, whereby the work conveying system can convey a single workpiece to each processing apparatus rapidly and in a predetermined sequence for predetermined processings. Consequently, the working efficiency of the work conveying system is greatly improved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a production line in a clean room having a work conveying system according to a first embodiment of the present invention; 
     FIG. 2 is a perspective view of a production line in a clean room according to a modification of the first embodiment of FIG. 1; 
     FIG. 3 is a front view of a vertical moving means of the work conveying system, in a raised state; 
     FIG. 4 is a side view of the vertical moving means of FIG. 3; 
     FIG. 5 is a front view showing the vertical moving means of FIG. 3 in a lowered state; 
     FIG. 6 is a side view of the vertical moving means in a lowered position; 
     FIG. 7 is a front view showing a raised state of a vertical moving means provided in a work conveying system according to a second embodiment, and corresponds to FIG. 3; 
     FIG. 8 is a plan view of a workpiece held by a work holding means in the work conveying system of the present invention; 
     FIG. 9 is a front view of an identification mark detecting device for detecting an identification mark affixed to a workpiece, the identification mark detecting device being installed within a clean room having a work conveying system according to a third embodiment of the present invention; 
     FIG. 10A is a front view of a vertical moving means of a conventional work conveying system, in a raised state; and FIG. 10B is a side view in vertical section of the same vertical moving means in a raised state; and 
     FIG. 11A is a front view of the vertical moving means of the conventional work conveying system shown in FIGS. 10A and 10B, but in a lowered state; and FIG. 11B is a side view in vertical section of the same vertical moving means in a lowered state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A first embodiment of the present invention will now be described with reference to FIGS. 1 to  6 . 
     In a production line  1  within a clean room to which the work conveying system of this first embodiment is applied, as shown in FIG. 1, plural processing chambers (processing apparatuses)  3  are arranged side by side in two rows, on a floor surface  2  in the clean room, with an interface device  4  attached to each processing chamber  3 . 
     The processing chambers  3  perform different process steps on workpieces in sequence. However, taking tact time in work processing into account, a plurality of identical processing chambers may be included in the production line. For example, the processing chambers  3  are semiconductor wafer processing units for conducting processes such as application of resist, exposure, development, ion implantation, annealing, and sputtering. Although the following description is provided with such processings of a semiconductor wafer in mind, the work conveying system in question is also applicable to reticle processing apparatus. 
     The interface devices  4  constitute buffer spaces for isolating the processing chambers  3  from the clean room. The delivery of workpieces to each processing chamber  3  is executed through the associated interface device  4 . A work inlet/outlet  5  in each interface device  4  is hermetically sealed except when loading or unloading a workpiece. 
     Adjacent processing chambers  3  and interface devices  4  are arranged to leave only a minimum maintenance area required for work by maintenance personnel or operating personnel. Thus, the floor area of the clean room which is occupied by such apparatus is minimized to make the most use of the clean room and to attain an efficient conveyance of workpieces by the work conveying system  10 , which will be described later. But it is not always necessary that the processing chambers  3  be arranged in plural rows, or with a front side (the side where each interface device  4  is provided) facing a particular direction. A certain degree of randomness of arrangement is allowed. 
     Mounted within the upper space of the clean room, the work conveying system  10  conveys a hermetically sealed container (work container)  6  to the processing chambers  3  in a predetermined sequence, the container  6  containing plural sheet-like workpieces, e.g. wafers or reticles. In order to maintain the required high-degree of cleanliness, the workpieces are conveyed in a hermetically sealed state within the container  6 . The floor surface  2  provides a space for the travel of work carriers  7 . When a work carrier  7  receives the hermetically sealed container  6  which has been conveyed from outside the clean room, the work carrier  7  travels to a predetermined position along a rail, and delivers the container  6  to the work conveying system  10 . 
     The work conveying system  10  is provided with work holding means  11  for holding the hermetically sealed container  6 , horizontal moving means  12  for moving the work holding means  11  horizontally within the upper ceiling space of the clean room, and vertical moving means  13  in the form of an articulated arm and provided in conjunction with the horizontal moving means  12 . In the vertical moving means  13 , the articulated arm is extended and contracted to raise and lower the work holding means  11 , thereby transferring workpieces between the work holding means  11  and each of the processing chambers  3 . A three-dimensional moving mechanism is provided by the combination of the horizontal moving means  12  and the vertical moving means  13 . 
     Horizontal Moving Means  12   
     As shown in FIG. 1, the horizontal moving means  12  comprises a pair of horizontal fixed guide rails  14  which are laid in parallel in the upper ceiling space within the clean room and traveling bodies  15  respectively installed on the fixed guide rails  14  and adapted to travel along the guide rails  14 . Though not shown in detail, a drive mechanism for each traveling body  15  has a motor integral with the traveling body  15  and received within the associated fixed guide rail  14 . A roller fixed onto a rotary shaft of the motor is adapted to roll along an inner wall surface of the fixed guide rail  14 , whereby the traveling body  15  is guided along the fixed guide rail. A base end portion of the vertical moving means  13  (a base end portion of the first start-end arm element  16 , which is described later) is pivotally connected to the traveling body  15  and is adapted to travel together with the traveling body  15 . 
     The horizontal moving means  12  may be modified as shown in FIG.  2 . In the horizontal moving means  12  in FIG. 2, a pair of horizontal fixed guide rails  14  are disposed in parallel in the upper ceiling space of the clean room and one or plural traveling guide rails  28  are mounted between the fixed guide rails  14 , and a traveling body  15 , adapted to travel along a traveling guide rail  28 , is carried on the same guide rail  28 . Thus, in this modification, the horizontal moving means  12  can arbitrarily move within the upper ceiling space of the clean room and in a horizontal plane sandwiched between the pair of fixed guide rails  14 . By moving the vertical moving means  13  and the work holding means  11  linearly from one position to another position on the opposite side with respect to the central passage, workpieces can be transferred between the work holding means  11  and each processing chamber  3 . The spacing between the pair of horizontal fixed guide rails  14  is set appropriately in accordance with the arrangement (installation position and orientation) of the processing chambers  3 , which spacing may be over the full width of the clean room. 
     Vertical Moving Means  13   
     As shown in FIGS. 3 to  6 , the vertical moving means  13  is an articulated arm having five arm elements  16 - 20 . As noted above, the base end portion of the first start-end arm element  16  is pivotally connected to the traveling body  15  so that the vertical moving means  13  can travel in a horizontal plane together with the traveling body  15 . 
     As best shown in FIGS. 4 and 6, the five arm elements  16 - 20  are successively arranged in an alternating manner such that, with respect to one virtual vertical plane A (see FIG.  4 ), the first start-end arm element  16  is located on the left-hand side, the second arm element  17  on the right-hand side, and the third arm element  18  on the left-hand side, the arm elements being overlapped and connected at their respective end portions. By so doing, the center of gravity of the articulated arm is not dislocated and the weight balance of the entire arm is stable, so that gravitational deflection is diminished upon extension of the articulated arm (upon lowering of the vertical moving means  13 ). Further, as is apparent from a comparison between FIG. 7 (conventional) and FIG. 4, the folded state of the vertical moving means  13  is compact, whereby disturbance of air with travel of the vertical moving means  13  is kept to a minimum. 
     The vertical moving means  13  has a motor  21  as the sole drive means and has a structure with a certain pivoting ratio (1:2:1:2:1) among the arm elements. The whole of the articulated arm (vertical moving means  13 ) extends and contracts with operation of the motor  21  and consequent pivotal movements of the arm elements  16 - 20 . As a result, the work holding means  11  fixed to the fifth terminal-end arm element  20  rises and falls on a straight line. These rising and falling motions are performed automatically under control of the motor  21 . With a pivoting ratio among the arm elements, which is based on 1:2:1, the number of arm elements which constitute the articulated arm is not limited to five, but may be three or seven. 
     As shown in FIGS. 4 and 6, the motor  21  is installed on the first arm element  16  side unlike the prior art wherein it is installed on the traveling body  15  side. An upper empty space in the interior of the first arm element  16  is utilized to receive the motor  21 . According to this construction, the sealing of dust generated by the motor  21  as the sole drive means and the sealing of dust generated from the pivoting among the arm elements may both be on the arm side, thus affording a structure easy to seal. The pivoting of the first start-end arm  16  for the horizontal moving means  12 , as well as the pivoting of the second to fifth arm elements  17 - 20 , are by operation of the motor  21 . The structure having a certain pivoting ratio of arm elements may be a known transmission mechanism such as one using plural pulleys having diameters of a predetermined ratio and plural belts gearing in the form of a linkage of only plural gears, or a linkage of only plural wires. 
     Joint shafts  22 - 25  (see FIG. 6) which pivotally connect adjacent arm elements of the five constituent arm elements  16 - 20  of the articulated arm, have a hollow structure, and the internal spaces of the arm elements  16 - 20  are in mutual communication and maintained at a negative pressure. A. work rotation drive unit  27  provided in the work holding means  11  also has a hollow structure which is in communication with the internal spaces of the arm elements  16 - 20  (see the communication path indicated by chain lines in FIG.  6 ). Dust generated from the drive unit is evacuated by the negative pressure to the arm side. 
     The dust generated in the internal spaces of the arm elements  16 - 20  and the work rotation drive unit  27  is evacuated into the hollow interior of the associated fixed guide rail  14  through the internal space of the traveling body  15  and is discharged to the exterior of the clean room from a discharge port formed on one end side of the guide rail. Alternatively, the air is discharged into the clean room through one or plural filters installed midway of the fixed guide rail  14 . Accordingly, this structure simplifies the discharge of dust generated in the internal spaces of the arm elements  16 - 20  and in the work rotation drive unit  27 . 
     As noted earlier, the work holding means  11  is fixed to the fifth terminal-end arm element  20 , and with work holder  26  holding the top of the hermetically sealed container  6 , the work holding means  11  is raised by the vertical moving means  13  and is conveyed to a predetermined processing chamber  3  by the horizontal moving means  12 . Then, when the work holding means  11  arrives at the predetermined processing chamber  3 , it is lowered by the vertical moving means  13  and the work holder  26  releases the container  6 , which in turn is placed on a table of the associated interface device  4 . At this time, if there is a necessity for correcting the orientation in which the container  6  is placed, the work rotation drive unit  27  in the work holding means  11  is operated to cause the container  6  to rotate a required degree in a horizontal plane, whereby the orientation in which the container  6  is placed can be corrected. 
     In operation of the first embodiment the center of gravity of the articulated arm is not dislocated, the weight balance of the entire arm is stable, and there occurs little gravitational deflection even upon extension of the articulated arm (upon lowering of the vertical moving means  13 ). Consequently, it becomes possible for the work holding means  11  to deliver the workpieces to each processing apparatus in succession without any positional deviation, and the extension and contraction of the articulated arm is smooth. Thus, when conveying the works horizontally, the disturbance of the air can be kept to a minimum by folding the vertical moving means  13  compactly. Since no torque is created by the weight of the entire arm and the weight of the workpieces, it is possible to effect a stable horizontal conveyance of the workpieces. 
     Further, since the work rotary drive unit  27  has a hollow structure in communication with the hollow interiors of the arm elements  16 - 20  and the dust generated from the drive unit is evacuated due to a negative pressure, the structure for discharging the dust generated in the rotary drive unit  27  is simplified, the discharge of the dust becomes easier, the amount of dust leaking into the clean room is greatly decreased, and it becomes still easier to maintain the cleanliness of the clean room. 
     Further, since plural workpieces in the form of wafers or reticles are received within the hermetically sealed container  6  and are held by the work holding means  11 , the workpieces are conveyed in a hermetically sealed state within the clean room and therefore it is also possible to easily attain the high-degree of cleanliness required for the workpieces. 
     Second Embodiment 
     A second embodiment of the invention will now be described with reference to FIGS. 7 and 8. Features also present in the first embodiment are identified by the same reference numerals. 
     In the work conveying system  10  of this second embodiment, a work holder  26  of a work holding means  11  directly holds a single workpiece  30  such as wafer or reticle, as shown in FIG.  7 . More specifically, plural hands  32  suspended from a lower surface of the work holder  26  hold the workpiece  30  at plural peripheral edge positions. 
     As shown in FIG. 8, an identification mark  31  indicating the process steps to which the workpiece  30  is to be subjected is affixed to each workpiece  30 , and a detector  34  for reading the identification mark  31  is provided on a lower surface of the work holder  26  of the work holding means  11 . 
     This second embodiment is different from the first embodiment with regard to the above-described features, but is not different with regard to other features of the first embodiment, so a detailed description thereof will be omitted. 
     In this second embodiment as described above, when the work holder  26  of the work holding means  11  holds a single workpiece  30 , the identification mark detecting means  34  detects the identification mark  31  affixed to the workpiece  30  and transmits a detection signal to the controller of the work conveying system  10 , which in turn conveys the workpiece  30  rapidly to each processing chamber (processing apparatus)  3  in a predetermined sequence, making it possible to process the workpiece  30  singly within the three-dimensional space of the clean room. Consequently, the working efficiency of the work conveying system  10  can be improved to a remarkable extent. 
     Third Embodiment 
     A third embodiment of the invention will now be described with reference to FIG.  9 . Features corresponding to those found in the second embodiment are identified by the same reference numerals. 
     In the work conveying system  10  of this third embodiment, an identification mark detecting device with detector  34  for detecting the identification mark  31  affixed to a single workpiece  30  is installed within the clean room. As shown in FIG. 9, the identification mark detecting device  33  is provided at an upper corner thereof with a projection  35  capable of entering between the lower surface of the work holder  26  in the work holding means  11  and the workpiece  30 . The detector  34  is provided on the lower surface of the projection  35 . Alternatively, the detector  34  may be incorporated in the tip of the projection  35 . 
     This third embodiment is different from the second embodiment with regard to the above-described features, but is not different from other features of the second embodiment, a detailed description of which will be omitted. 
     In this third embodiment as described above, the identification mark detecting device  33  detects the identification mark  31  affixed to the individual workpiece  30  which has been conveyed to the position where the detecting device is installed and transmits the detection signal to the controller of the work conveying system  10 , which in turn conveys the individual workpiece  30  rapidly to each processing chamber (processing apparatus)  3  in a predetermined sequence, thus permitting the workpiece to be subjected to various operations. In this way it is possible to greatly improve the working efficiency of the work conveying system  10 . 
     The present invention is not limited to the above embodiments, but various modifications may be made without departing from the gist of the invention. 
     The entirety of the teachings of Japanese patent applications Nos. 2001-253910 and 2001-283407, inclusive of their specifications, claims and drawings, are incorporated herein by reference.