Patent Publication Number: US-2004052626-A1

Title: Board-conveying robot

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application claims the benefit of Korean Patent Application No. 2002-56845 filed on Sep. 18, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates, in general, to robots and, more particularly, to a board-conveying robot which conveys semiconductor wafers, liquid crystal display boards and other boards.  
       [0004] 2. Description of the Related Art  
       [0005] Robots are used for various purposes in various industrial fields. For example, robots are used to convey boards in a semiconductor manufacturing field. The term “boards” designates semiconductor wafers, liquid crystal display (LCD) panels, unit discs of a disc drive, etc. Such a board is delivered to a corresponding working area of a production line after being loaded onto a conveyance container that is generally called a cassette. A board-conveying robot is used to withdraw the board loaded onto the cassette to execute corresponding processing in a unit manufacturing process of the production line, and then load the processed board again onto the cassette.  
       [0006]FIG. 1A is a perspective view of a conventional board-conveying robot. As shown in FIG. 1A, two vertical axis arms  102  and  104  used to control vertical movement are connected to a vertical axis base  124  to be rotatable around respective pivots. The first vertical axis arm  102  is connected to the vertical axis base  124  to be rotatable around a pivot  152 . The second vertical axis arm  104  is connected to an upper end of the first vertical axis arm  102  to be rotatable around a pivot  154  and to a vertical axis base  166  to be rotatable around a pivot  156 . The first vertical axis arm  102  is rotated by using a motor  110  as an electric power source.  
       [0007] A horizontal axis base  166  to which a first horizontal axis arm  106  is connected to be rotatable around a pivot  158  is connected to an upper end of the second vertical axis arm  104 . A second horizontal axis arm  108  is connected to an upper end of the first horizontal axis arm  106 . The first horizontal axis arm  106  is rotated by using a motor  112  as an electric power source. An end effector  122  is coupled to an upper end of the second horizontal axis arm  108  to be rotatable around a pivot  162  by using a motor  114  as an electric power source. A hand  118  to hold a board  120  is connected to the end effector  122  to be rotatable around a pivot  164 . The hand  118  is rotated around the pivot  164 , thus horizontally and vertically holding the board  120 .  
       [0008]FIG. 1B is a view showing the board-conveying robot of FIG. 1A whose horizontal axis arms  106  and  108  are maximally folded. As shown in FIG. 1B, even though the horizontal axis arms  106  and  108  are maximally folded, there is a dead zone in which the hand  118  is prohibited from further approaching the center of the vertical axis base  124 . Due to the dead zone, a working radius of the board-conveying robot is inevitably increased.  
       [0009] The conventional board-conveying robot has only one hand, resulting in the following limitations in work efficiency. That is, a process of feeding a board into a production line to carry out a corresponding process, conveying a processed board again to the cassette and loading the board onto the cassette is considered as a single cycle. Hence, until an operation of one cycle for one board is completed, the conventional board-conveying robot may not perform another operation (for example, conveyance of a new board). Thus, work efficiency is not greatly increased. That is, until a board fed into a production line has been completely processed, the board-conveying robot must stand by at the production line, inevitably decreasing work efficiency.  
       [0010] To increase work efficiency, a method of operating two hands in the board-conveying robot having the construction of FIG. 1A may be considered. However, in the method using two hands, a set of horizontal axis arms must be additionally arranged, and working areas of respective horizontal axis arms must be clearly divided to prevent mutual interference between the two sets of horizontal axis arms. Consequently, work efficiency is not greatly improved and a control system of a board-conveying robot becomes more complicated. Thus, the above method of operating two hands may not be a desirable alternative solution for increasing work efficiency.  
       SUMMARY OF THE INVENTION  
       [0011] Accordingly, it is an aspect of the present invention to provide a board-conveying robot in which the construction of a horizontal axis arm and hands are improved to reduce a working radius of the board-conveying robot and increase work efficiency thereof.  
       [0012] Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
       [0013] The foregoing and other aspects of the present invention are achieved by providing a board-conveying robot including at least one vertical axis arm designed to control a height of the board-conveying robot and a horizontal axis arm arranged to allow at least one hand to move rectilinearly to hold an object. Further, the horizontal axis arm is fixedly connected to a head which is rotatably connected to an upper end of the vertical axis arm to move the horizontal axis arm between vertical and horizontal orientations. Further, the board-conveying robot has two hands which are constructed to move in parallel with each other along two guide rails formed in parallel with each other on the horizontal axis arm. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] These and other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
     [0015]FIG. 1A is a perspective view of a conventional board-conveying robot;  
     [0016]FIG. 1B is a view showing the board-conveying robot of FIG. 1A whose horizontal axis arms are maximally folded;  
     [0017]FIG. 2A is a perspective view of a board-conveying robot according to an embodiment of the present invention;  
     [0018]FIG. 2B is a view showing the board-conveying robot of FIG. 2A with both hands vertically oriented;  
     [0019]FIGS. 3A and 3B are views showing the internal construction of vertical axis arms of the board-conveying robot of FIG. 2A; and  
     [0020]FIG. 4 is a view showing another board-conveying robot according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
     [0021] Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
     [0022] Embodiments of board-conveying robots of the present invention are described in detail with reference to FIGS. 2A to  4 . FIG. 2A is a perspective view of a board-conveying robot according to an embodiment of the present invention, and shows that hands  214  and  218  are horizontally oriented. As shown in FIG. 2A, a board-conveying robot  200  of the present invention conveys a board  228  between a production line (process chamber or furnace, etc.)  224  and a cassette  226 .  
     [0023] A base  204  of the board-conveying robot  200  is arranged to move rectilinearly along a track  202 , and is rotatable through 360 degrees on a X-Y plane. The length of the track  202  may be extended if necessary. On the base  204 , first and second vertical axis arms  206  and  210  are arranged in order. In this embodiment, the first vertical axis arm  206  is rotated vertically to the X-Y plane by using a motor  208  as an electric power source. The second vertical axis arm  210  subordinated to the movement of the first vertical axis arm  206  is also rotated vertically to the X-Y plane while being rotated opposite to the first vertical axis arm  206 .  
     [0024] A head  222  is connected to an upper end of the second vertical axis arm  210  to be rotatable vertically by using a motor ( 222   a  of FIG. 3A) installed in an upper portion of the second vertical axis arm  210  as an electric power source. Contrary to the second vertical axis arm  210  subordinated to the first vertical axis arm  206 , the rotation of the head  222  is independent of the first and second vertical axis arms  206  and  210 .  
     [0025] A horizontal axis arm  212  is arranged on the head  222 , wherein the longitudinal direction of the horizontal axis arm  212  is orthogonal to the rotating direction of the vertical axis arms  206  and  210 . Two guide rails  216  and  220  are formed on the horizontal axis arm  212  along the longitudinal direction of the horizontal axis arm  212 . Further, two hands  214  and  218  constructed to be complementary are arranged to rectilinearly reciprocate along the guide rails  216  and  220 , respectively, in the longitudinal direction of the horizontal axis arm  212 . The hands  214  and  218  are used to hold the board  228 . The first hand  214  is formed in the shape of a rectangle having an empty center portion to allow the second hand  218  to penetrate through the first hand  214 . The center of the lower portion of the rectangle of the first hand  214  is cut to enable a supporter  218   a  of the second hand  218  to pass through the cut portion. In the horizontal axis arm  212 , a mechanical structure is provided to enable the first and second hands  214  and  218  to reciprocate. By this structure, the first and second hands  214  and  218  may freely reciprocate rectilinearly along the longitudinal direction of the horizontal axis arm  212  without mutual interference.  
     [0026] By using the above-described two hands  214  and  218 , two boards may be conveyed during a single operating cycle, which is described in detail.  
     [0027] (1) A first board to be fed into a process is withdrawn from the cassette  226  using the first hand  214 .  
     [0028] (2) The hands  214  and  218  are set to face the production line  224  by rotating the base  202  at an angle of 180 degrees.  
     [0029] (3) The first board held on the first hand  214  is fed into the production line  224 .  
     [0030] (4) A second board to be fed into the production line  224  is withdrawn from the cassette  226  using the first hand  214  while the process of the production line  224  is carried out on the first board.  
     [0031] (5) After the process for the first board is completed, the processed first board is withdrawn from the production line  224  using the second hand  218 , and the second board held on the first hand  214  is fed into the production line  224 .  
     [0032] (6) The processed first board which is held on the second hand  218  is conveyed to and loaded onto the cassette  226 .  
     [0033] (7) The operations (1) to (6) are repeated.  
     [0034] As shown in the above operations (1) to (7), the board-conveying robot of the present invention may withdraw a board from the cassette  226  and allow the board to stand by at the production line  224  while a process for another board is carried out. Therefore, immediately after the process for the board fed into the production line  224  is completed, the processed board may be withdrawn and a new board may be fed into the production line  224 . Further, while a process for the board fed into the production line  224  is carried out, the processed board is loaded onto the cassette  226  and thereafter a new board is immediately withdrawn from the cassette  226  to stand by at the production line  224 . As described above, high work efficiency is achieved due to the fact that the board-conveying robot is operated using the two hands  214  and  218 .  
     [0035]FIG. 2B is a view showing the board-conveying robot of FIG. 2A with its hands  214  and  218  vertically oriented. As shown in FIG. 2B, the head  222  is rotated independently of the first and second vertical axis arms  206  and  210 , so the hands  214  and  218  may move to vertical orientations, thus easily performing an operation of vertically drawing out a board or vertically loading a board.  
     [0036]FIGS. 3A and 3B are views showing the internal construction of the vertical axis arms  206  and  210  of the board-conveying robot of FIG. 2A. That is, FIG. 3A is a view showing a rotational relationship between the vertical axis arms  206  and  210 . As shown in FIG. 3A, when the first vertical axis arm  206  is rotated by the motor ( 208  of FIG. 2A), its rotary force is transferred to the second vertical axis arm  210  through a belt  206   a , thus rotating the second vertical axis arm  210 . At this time, the velocity ratio of two decelerators  206   b  and  206   c  is 1:2, and may cause the head  222  to be vertically oriented while maintaining a same position. Therefore, to maintain the horizontal axis arm  212  in a horizontal orientation, the velocity ratio of the two decelerators  206   b  and  206   c  and the motor  222   a  is 1:2:1. However, since the head  222  is independently rotated by the motor  222   a , the rotation of the head  222  at velocity ratios deviating from the above velocity ratio may be performed. In this embodiment, the hands  214  and  218  may move to vertical orientations through the rotation of the head  222 . Accordingly, the hands  214  and  218  move to vertical orientations to permit boards to be withdrawn vertically or vertically loaded.  
     [0037]FIG. 3B is a view showing the wiring structure within the vertical axis arms  206  and  210  of the board-conveying robot of the present invention. As shown in FIG. 3B, wiring holes  304   a  and  304   b  are provided within the base  204 , the vertical axis arms  206  and  210  and the horizontal axis arm  212  to allow a wire  302  to pass therethrough. Accordingly, control cables and power cables may be installed within the arms  206 ,  210  and  212  through the wiring holes  304   a  and  304   b.    
     [0038]FIG. 4 is a view showing another board-conveying robot according to another embodiment of the present invention, and shows that a motor  404  used to rotate a head  402  and a motor  406  used to rotate a horizontal axis arm  408  are mounted within the head  402 . The motor  404  rotates the head  402  to move hands  412  and  414  from a horizontal orientation to a vertical orientation. The motor  406  enables the horizontal axis arm  408  to rotate on a horizontal plane. In the embodiment of FIG. 4, the motor  406  rotates only the horizontal axis arm  408 , wherein the board-conveying robot may employ a motor having a lower output compared with an embodiment where the board-conveying robot of the present invention is entirely rotated through the rotation of the base  410 , thus reducing production costs.  
     [0039] As is apparent from the above description, the present invention provides a board-conveying robot, which can reduce a working radius and increase work efficiency by improving the construction of a horizontal axis arm and hands.  
     [0040] Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.