Abstract:
An article transfer apparatus suitable for an operation requiring a large vertical working distance. The apparatus includes a first link driven by a motor, at least one second link coupled to the first link, and a mounting member coupled to the last one of the second link and loaded with an article to transfer. The individual links are pivotally moved using a combination of a supporting shaft, a rotating shaft and a swiveling shaft which are provided on the previous link, and the mounting member is moved upward by the shafts provided on the last link. Bevel gears are provided on the ends of the supporting shaft and the swiveling shaft and on both ends of the rotating shaft, and engaged with one another. The gear ratio between the bevel gear of the rotating shaft and that of the swiveling shaft is 2:1 on the first link and 1:2 on the last link. The other bevel gears are engaged with each other at a gear ratio of 1:1. According to these gear ratios, the individual links are moves upward along a same axis and the mounting member is moved while maintained in parallel with the horizontal plane.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an article transfer apparatus and, more particularly, to an article transfer apparatus suitable to vertically move an article such as wafer, panel or computer hard disc to a desired position. 
     2. Description of the Related Art 
     Generally, in the manufacturing process of a semiconductor device or electronic appliance, there is a need of an apparatus equipped with an arm that is designed to make a horizontal or vertical motion in order to move a wafer or hard disc to a desired position. FIG. 1 illustrates an example of the conventional apparatus for moving an article in the vertical direction, which is disclosed in U.S. Pat. No. 5,993,142. 
     Referring to FIG. 1, the apparatus comprises: a plurality of lead screws  2  and a driving motor (not shown) mounted on a base  1 ; a plurality of vertical structures  3  each having a hollow to receive the individual lead screws  2 ; an elevator  4  provided at the bottom end of the individual vertical structures  3  and engaged with the lead screws  2 ; a flange  5  provided at the top end of the individual vertical structures  3 ; a link L 1  disposed between the vertical structures  3  and provided on the top of the flange  5 ; links L 2  and L 3  connected in series to the one end of the link L 1 ; and a motor  6  and an end effector  7  connected to the end of the link L 3 . 
     Once the driving motor (not shown) mounted on the base  1  operates, the lead screws  2  associated with the motor via a belt is turned so that the elevators  4  engaged with the lead screws  2  are moved up or down depending on the direction of rotation of the motor. The vertical structures  3  correspondingly make an up-and-down motion in a telescopic manner, thereby moving an article placed on the end effector  7  to a desired position. 
     Such a conventional apparatus as constructed above, however, has the individual vertical structures vertically climbing in a telescopic manner along the lead screws and thus occupies a vertical space as high as the height of the lead screws even in the off state. It is thus disadvantageous in that the apparatus has a non-conveyable region as large as the height of the lead screws in the off state. 
     Furthermore, the conventional apparatus requires excessively many parts substantially necessary to the structure and consists of complex connections between the motor, the lead screws and the vertical structures, which leads to an increase in the production cost and the manufacturing period. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention to solve the problems is to provide an article transfer apparatus having a simple structure and operational mechanism, and requiring a short vertical working distance in a non-operated state. 
     To achieve the above object, there is provided an article transfer apparatus including: a base; a supporting shaft fixed on the base; a first link having one end pivotally coupled to the supporting shaft; a second link having one end pivotally coupled to the other end of the first link; a mounting member coupled to the second link and loadable with an article to be transferred; a driving motor for pivotally moving the first link with a swiveling force; a rotating shaft rotatably provided along the first link and rotated by the swiveling force of the first link; and a swiveling shaft having one end fixed on the one end of the second link, and the other end coupled to the rotating shaft of the first link, the swiveling shaft receiving the swiveling force of the rotating shaft and pivotally moving the second link. 
     A rotating bevel gear is provided on both ends of the rotating shaft, and a fixed bevel gear is provided on the one end of the supporting shaft and is engaged with the rotating bevel gear provided on the one end of the rotating shaft. And, a swiveling bevel gear is provided on the other end of the swiveling shaft and is engaged with the rotating bevel gear provided on the other end of the rotating shaft. Thus the pivotal motion of the first link causes the rotating shaft to be turned, and the swiveling force of the rotating shaft pivotally moves the swiveling shaft coupled to the second link, thereby pivotally moving the second link. 
     The rotating shaft includes: a first sub shaft having both ends each provided with a bevel gear, and the one end thereof engaged with the fixed bevel gear of the supporting shaft; a second sub shaft having both ends each provided with a bevel gear, and the one end thereof engaged with the swiveling bevel gear of the swiveling shaft; and a switching shaft rotatably mounted in the first link and having a rotating bevel gear concurrently engaged with both the bevel gears provided on the other ends of the first and second sub shafts. 
     Thus the pivotal upward or downward motion of the first link causes the second link to pivotally move in the same direction, i.e., upward or downward. 
     The rotating bevel gear of the switching shaft is engaged with the bevel gears of the first and second sub shafts at a gear ratio of 1:1, and the bevel gear of the second sub shaft is engaged with the bevel gear of the swiveling shaft at a gear ratio of 2:1. Accordingly, the swiveling angle of the second link is double the swiveling angle of the first link, so that both ends of the individual links are moved upward along the same axis. 
     The article transfer apparatus further includes: a second supporting shaft having one end fixed on the first link and the other end extending to the second link for pivotally supporting the second link and being coaxial with the swiveling shaft fixed on the second link; a second rotating shaft mounted along the second link to be rotated by the swiveling force of the second link; and a second swiveling shaft having one end fixed on the mounting member and the other end coupled to the second rotating shaft of the second link, the second swiveling shaft receiving the swiveling force of the second rotating shaft and pivotally moving the mounting member. 
     A rotating bevel gear is provided on both ends of the second rotating shaft, and a fixed bevel gear is provided on the other end of the second supporting shaft and engaged with the bevel gear fixed on the adjacent one end of the second rotating shaft. And, a swiveling bevel gear is provided on the other end of the second swiveling shaft and engaged with the bevel gear fixed on the adjacent other end of the second rotating shaft. Thus the pivotal motion of the second link causes the second rotating shaft to be turned, and the turning force of the second rotating shaft pivotally moves the second swiveling shaft together with the mounting member. 
     The bevel gear of the second rotating shaft provided on the second link is engaged with the bevel gear of the second supporting shaft fixed on the first link at a gear ratio of 1:1, and a bevel gear of the second rotating shaft is engaged with the bevel gear of the second swiveling shaft fixed on the mounting member at a gear ratio of 1:2. As a result, the swiveling angle of the mounting member is a half of the swiveling angle of the second link, so that the mounting member can be ascending while maintaining in parallel with the horizontal plane. 
     In another embodiment of the present invention, the second link includes a plurality of sub links serially coupled in the same manner as the engagement structure made between the first and second links, and the mounting member is provided on the final sub link. This elongates the vertical transfer distance of the mounting member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal sectional view of an article transfer apparatus according to a prior art; 
     FIG. 2 is a transversal sectional view of an article transfer apparatus in a non-operated state according to a first embodiment of the present invention; 
     FIG. 3 is a side view of the article transfer apparatus shown in FIG. 2; 
     FIG. 4 is a front view explaining a vertical ascending operation of the article transfer apparatus according to the first embodiment of the present invention; 
     FIG. 5 is a front view showing the article transfer apparatus extended to the maximum vertical height according to the first embodiment of the present invention; 
     FIG. 6 is a front view explaining a vertical descending operation of the article transfer apparatus according to the first embodiment of the present invention; 
     FIG. 7 is a transversal sectional view of an article transfer apparatus in a non-operated state according to a second embodiment of the present invention; and 
     FIG. 8 is a front view explaining a vertical ascending operation of the article transfer apparatus according to the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 2 is a transversal sectional view of an article transfer apparatus in a non-operated state according to a first embodiment of the present invention, and FIG. 3 is a side view of the article transfer apparatus shown in FIG.  2 . 
     As illustrated, the article transfer apparatus according to the first embodiment comprises: a base  10 ; a driving motor  20  fixed on the base  10  and including a reduction gear member (not shown); a first link  30  associated with the reduction gear member of the driving motor  20 ; second, third and fourth links  50 ,  70  and  90  sequentially connected in parallel to the first link  30 ; and a mounting member  120  having a swing arm  121  and a plurality of conveying arms  122  and associated with the fourth link  90 . The links  30 ,  50 ,  70  and  90  have a hexahedral or cylindrical structure provided with an inner space. 
     Although it is expediently assumed that four links are provided in the present invention, the number of links may be at least two within the scope of the present invention. A description on an article transfer apparatus with two links will be given later in connection to the second embodiment of the present invention. 
     As a driving shaft (not shown) of the reduction gear member is associated with the exterior side of a front portion of the first link  30 , the driving motor  20  fixed on the base  10  causes the first link  30  to be pivotally moved with respect to the front end thereof. An AC servomotor may be used as the driving motor  20 . 
     The first link  30  is internally provided with a supporting shaft  31 , a swiveling shaft  35 , and a rotating shaft  40 , which are to pivotally move the second link  50  arranged in parallel with the first link  30 . 
     The supporting shaft  31 , piercing the first link  30 , is disposed opposite to the driving motor  20  and fixedly associated with a bracket  11  fixed on the base  10 . A fixed bevel gear  32  is provided at the end of the supporting shaft  31 , and a bearing member  49  is provided at the portion of the supporting shaft  31  piercing the first link  30 , thereby pivotally supporting the first link  30 . 
     The swiveling shaft  35 , piercing the first link  30 , is disposed at a rear portion of the first link  30  and fixed on the exterior side of a front portion of the second link  50 , so that it pivotally moves in engagement with the second link  50 . 
     A swiveling bevel gear  36  is provided at the end of the swiveling shaft  35 . The swiveling shaft  35  is internally provided with a hollow portion  37 . 
     The rotating shaft  40  has first and second sub shafts  41  and  44 , and a switching shaft  47  connecting the first and second sub shafts  41  and  44  to switch the rotational direction. 
     The switching shaft  47  is pivotally provided on the first link  30  and a rotating bevel gear  48  is formed at the end of the switching shaft  47 . 
     The first sub shaft  41  has both ends provided with bevel gears  42  and  43 , which are engaged with the fixed bevel gear  32  of the supporting shaft  31  and the rotating bevel gear  48  of the switching shaft  47 , respectively. The second sub shaft  44  has both ends provided with bevel gears  45  and  46 , which are engaged with the rotating bevel gear  48  of the switching shaft  47  and the swiveling bevel gear  36  of the swiveling shaft  35 , respectively. 
     The first link  30  is internally provided with a plurality of shaft-receiving members  110  in order to rotatably support the first and second sub shafts  41  and  44 . These shaft-receiving members  110  are bolted to the first link  30  and provided with bearings at a portion thereof pierced by the first and second sub shafts  41  and  44 , thereby rotatably supporting the sub shafts  41  and  44 . 
     The bevel gear  32  of the supporting shaft  31 , the bevel gears  42 ,  43  and  45  of the first and second sub shafts  41  and  44 , and the bevel gear  48  of the switching shaft  47  are engaged with one another at a gear ratio of 1:1. The bevel gear  46  of the second sub shaft  44  is engaged with the bevel gear  36  of the swiveling shaft  35  at a gear ratio of 2:1. 
     According to these gear ratios, when the first link  30  turns by θ, the second link  50  pivotally moves by 2θ, as illustrated in FIG.  4 . 
     In a similar way to the first link  30 , the second link  50  is internally provided with a supporting shaft  51 , a swiveling shaft  55 , and a rotating shaft  60 , which are to pivotally move the third link  70  arranged in parallel with the second link  50 . 
     The supporting shaft  51 , piercing the second link  50  and the swiveling shaft  35  of the first link  30 , is disposed at a front portion of the second link  50  and bolted to the inside of the first link  30 . A fixed bevel gear  52  is provided at the end of the supporting shaft  51 , and the bearing member  49  is provided at the portion of the supporting shaft  51  piercing the second link  50  and the swiveling shaft  35  of the first link  30 , thereby pivotally supporting the second link  50 . 
     The swiveling shaft  55 , piercing the second link  50 , is disposed at a rear portion of the second link  50  and fixed on the exterior side of a front portion of the third link  70 , so that it pivotally moves in engagement with the third link  70 . 
     A swiveling bevel gear  56  is provided at the end of the swiveling shaft  55 . The swiveling shaft  55  is internally provided with a hollow portion  57 . 
     Contrary to the case of the first link  30 , the shaft  60  has a single long rod-shaped structure. On both ends of the shaft  60  are provided rotating bevel gears  61  and  62 , which are engaged with the bevel gear  52  of the supporting shaft  51  and the bevel gear  56  of the swiveling shaft  55 , respectively. 
     The second link  50  is also internally provided with a plurality of shaft-receiving members  110  similar to those of the first link  30  in order to pivotally support the shaft  60 . 
     The bevel gear  52  of the supporting shaft  51 , the bevel gears  61  and  62  of the shaft  60 , and the bevel gear  56  of the swiveling shaft  55  are engaged with one another at a gear ratio of 1:1. According to this gear ratio, when the second link  50  turns by 2θ, the third link  70  also pivotally moves by 2θ, as illustrated in FIG.  4 . 
     In a similar way to the second link  50 , the third link  70  is internally provided with a supporting shaft  71 , a swiveling shaft  75 , and a rotating shaft  80 , which are to pivotally move the fourth link  90  arranged in parallel with the third link  70 . 
     The supporting shaft  71 , piercing the third link  70  and the swiveling shaft  75  of the second link  50 , is disposed at a front portion of the third link  70  and bolted to the inside of the second link  50 . A fixed bevel gear  72  is provided at the end portion of the supporting shaft  71 , and the bearing member  49  is provided at the portion of the supporting shaft  71  piercing the third link  70  and the swiveling shaft  55  of the second link  50 , thereby pivotally supporting the third link  70 . 
     The swiveling shaft  75 , piercing the third link  70 , is disposed at a rear portion of the third link  70  and fixed on the exterior side of a front portion of the fourth link  90 , so that it pivotally moves in engagement with the fourth link  90 . 
     A swiveling bevel gear  76  is provided at the end of the swiveling shaft  75 . The swiveling shaft  75  is internally provided with a hollow portion  77 . 
     On both ends of the rotating shaft  80  are provided rotating bevel gears  81  and  82 , which are engaged with the bevel gear  72  of the supporting shaft  71  and the bevel gear  76  of the swiveling shaft  75 , respectively. The third link  70  is also internally provided with a plurality of shaft-receiving members  110  in order to pivotally support the rotating shaft  80 . The bevel gear  72  of the supporting shaft  71 , the bevel gears  81  and  82  of the rotating shaft  80 , and the bevel gear  76  of the swiveling shaft  75  are engaged with one another at a gear ratio of 1:1. According to this gear ratio, when the third link  70  turns by 2θ, the fourth link  90  also pivotally moves by 2θ, as illustrated in FIG.  4 . 
     In a similar way to the second and third links  50  and  70 , the fourth link  90  is internally provided with a supporting shaft  91 , a swiveling shaft  95 , and a rotating shaft  100 , which are to vertically move the mounting member  120  associated with a rear portion of the fourth link  90 , while maintaining the mounting member  120  in parallel with the horizontal plane. 
     The supporting shaft  91 , piercing the fourth link  90  and the swiveling shaft  75  of the third link  70 , is disposed at a front portion of the fourth link  90  and bolted to the inside of the third link  70 . A fixed bevel gear  92  is provided at the end of the supporting shaft  91 , and the bearing member  49  is provided at the portion of the supporting shaft  91  piercing the fourth link  90  and the swiveling shaft  75  of the third link  70 , thereby pivotally supporting the fourth link  90 . 
     The swiveling shaft  95 , piercing the fourth link  90 , is disposed at a rear portion of the fourth link  90  and fixed on the swing arm  121  of the mounting member  120 , so that it pivotally moves in engagement with the mounting member  120 . A swiveling bevel gear  96  is provided at the end of the swiveling shaft  95 , and the bearing member  49  is provided at the portion of the swiveling shaft  95  piercing the fourth link  90 , thereby pivotally supporting the mounting member  120 . 
     On both ends of the rotating shaft  100  are provided rotating bevel gears  101  and  102 , which are engaged with the bevel gear  92  of the supporting shaft  91  and the bevel gear  96  of the swiveling shaft  95 , respectively. The fourth link  90  is also internally provided with a plurality of shaft-receiving members  110  in order to pivotally support the rotating shaft  100 . The bevel gear  92  of the supporting shaft  91  is engaged with the bevel gear  101  of the rotating shaft  100  at a gear ratio of 1:1, while the bevel gear  102  of the rotating shaft  100  is engaged with the bevel gear  96  of the swiveling shaft  95  at a gear ratio of 1:2. According to these gear ratios, when the fourth link  90  turns by 2θ, the mounting member  120  pivotally moves only by θ, while maintained in parallel with the horizontal plane, as illustrated in FIG.  4 . 
     FIGS. 4,  5  and  6  illustrate a climbing and descending operation of the above-structured article transfer apparatus according to the first embodiment of the present invention. 
     Now, a description will be given to the operation of the present invention with reference to the figures. 
     As shown in FIG. 4, when the driving motor  20  is driven in a direction to extend the links upward in order to move the mounting member  120  up to a desired height, the first link  30  connected to the reduction gear (not shown) pivotally moves upward by a predetermined angle (θ) corresponding to the desired height. Meanwhile, as the supporting shaft  31  is fixed on the base  10  by the bracket  11  (FIG.  2 ), the pivotal motion of the first link  30  causes the bevel gear  42  of the first sub shaft  41  to rotate along the bevel gear  32  of the supporting shaft  31  in a direction of the arrow shown in FIG.  4 . The rotation of the first sub shaft  41  makes the switching shaft  47  turn in a direction of the arrow shown in FIG.  4  and the second sub shaft  44  turn in a reverse direction of the first sub shaft  41 . 
     Due to the turning forces of the shafts  41 ,  44  and  47 , the swiveling shaft  35  having the bevel gear  36  engaged with the bevel gear  46  of the second sub shaft  44  is rotated so that the second link  50  associated with the swiveling shaft  35  is pivotally moved upward with respect to the supporting shaft  51 . The swiveling angle of the second link  50  is double (e.g., 2θ) the swiveling angle (e.g., θ) of the first link  30 , since the bevel gear  46  of the second sub shaft  44  is engaged with the bevel gear  36  of the swiveling shaft  35  at a gear ratio of 2:1. 
     As the bevel gear  61  of the shaft  60  provided in the second link  50  is in engagement with the bevel gear  52  of the supporting shaft  61 , the pivotal motion of the second link  50  causes the shaft  60  not only to pivotally move with the second link  50  but also to rotate in a direction of the arrow shown in FIG.  4 . The turning force of the rotating shaft  60  is transferred to the bevel gear  56  of the swiveling shaft  55  engaged with the bevel gear  62  of the rotating shaft  60  so as to turn the swiveling shaft  55 . This causes the third link  70  associated with the swiveling shaft  55  to pivotally move upward with respect to the supporting shaft  71 . The swiveling angle of the third link  70  is equal to the swiveling angle (e.g., 2θ) of the second link  50 , because the bevel gears of the second link  50  are engaged with one another at a gear ratio of 1:1. 
     The fourth link  90  makes a pivotal motion in the same manner as described above. That is, the pivotal motion of the third link  70  causes the shaft  80  provided in the third link  70  not only to pivotally move with the third link  70  but also to rotate in a direction of the arrow shown in FIG.  4 . The turning force of the rotating shaft  80  rotates the swiveling shaft  75 , which in turn causes the fourth link  90  associated with the swiveling shaft  75  to pivotally move upward with respect to the supporting shaft  91 . The swiveling angle of the fourth link  90  is equal to the swiveling angle (e.g., 2θ) of the third link  70 , since the bevel gears of the third link  70  are engaged with one another at a gear ratio of 1:1. 
     As the fourth link  90  makes a pivotal motion, the rotating shaft  100  provided in the fourth link  90  is turned in a direction of the arrow shown in FIG. 4 in the same manner as described above. The turning force of the rotating shaft  100  is transferred to the swiveling shaft  95  via the bevel gear  102  of the rotating shaft  100  and the bevel gear  96  of the swiveling shaft  95  so as to turn the swing arm  121  of the mounting member  120  associated with the swiveling shaft  95 , thereby pivotally moving the mounting member  120 . The swiveling angle of the mounting member  120  is a half (e.g., θ) of the swiveling angle (e.g., 2θ) of the fourth link  90 , because the bevel gear  92  is engaged with the bevel gear  101  at a gear ratio of 1:1 and the bevel gear  102  is engaged with the bevel gear  96  at a gear ratio of 1:2. 
     When ascending the individual links with the aforementioned structure and gear ratios, the end portions of the links move along the same axial line Y—Y. This maintains the postures of the links and the mounting member as illustrated in FIG. 4 even when the links are moved at whatever angle, so that the mounting member  120  can be moved upward in parallel with the horizontal plane. 
     FIG. 5 shows the article transfer apparatus of the invention extended to the maximum vertical height, in which the first link  30  and the mounting member  120  have a swiveling angle of 90° and the second, third and fourth links  50 ,  70  and  90  have a swiveling angle of 180°. 
     FIG. 6 shows the article transfer apparatus of the invention folded in a non-operated state after the completion of article conveyance. As the driving motor  20  rotates in a direction to descend the links, as indicated by the arrow of FIG. 6, the individual shafts are rotated in the reverse direction of FIG. 4 to move the links down. 
     FIGS. 7 and 8 are illustrations of an article transfer apparatus according to a second embodiment of the present invention. This embodiment suggests that the article transfer apparatus of the invention can be implemented with at least two links. In FIG. 7, a first link  30 A, internal shafts of the first link  30 A, and gear ratios are analogous to the first link  30 , the internal shafts of the link  30 , and the gear ratios in FIG. 2, and a second link  90 A, internal shafts of the second link  90 A, and gear ratios are similar to the fourth link  90 , the internal shafts of the link  90 , and the gear ratios in FIG.  2 . It is therefore to be noted that like reference numerals as used in the first embodiment denote the same components other than the links in the drawings. 
     FIG. 8 is an illustration corresponding to FIG. 4, in which the first and second links  30 A and  90 A are pivotally moved upward to make the mounting member  120  move upward in parallel with the horizontal plane. The operation of the article transfer apparatus in the second embodiment is analogous to that of the article transfer apparatus in the first embodiment and its description will be avoided. 
     As described above, the article transfer apparatus of the present invention has at least two links arranged in parallel and connected to be extendable and occupy less space for installation in a non-operated state, thus improving the operating efficiency and increasing the working area. 
     Furthermore, the article transfer apparatus has a structure with reduced complexity and a smaller number of parts, which may provide a contribution to the reduction of production cost and time.