| 摘要 |
PURPOSE:To revolve a disc at a specified angle by a method wherein a spiral cam is provided on the rotating axis of a disc, while controlling the rotation by utilizing the groove of the axis. CONSTITUTION:A stand 1 and a disc 2 on which a wafer 28 is placed are transferred by a lever 19 toward the right, and they are arranged to stand at a position r/3 (r denotes the radius of the wafer) from the center of the wafer, then they are measured at 3 points while moving them to the left gradually. Next the stand 1 is moved to the right and the claw of a roller 5 is engaged with the groove of a spiral cam 4, then a guide pin 12 is inserted into a positioning hole provided on one side of the cam after compressing a spring 9 further. In addition, if the stand 1 is transferred to the right side, the cam 4 will turn right, and the disc 2 will turn by 90 deg. via an axis 13 as well as gears 141, 142, 61, 62. Next since the roller 5 is engaged with the groove of another cam and a control piece is lowered if the stand 1 is transferred to the left side, the cam 4 and the disc 2 do not rotate. After making measurements at the positions 4, 5, the roller 5 moves as it is engaged with the groove of another cam if the stand is transferred to the right again, and the roller turns left on the other hand. In this way, the transfer of the stand in one direction makes possible the measurements at 3 positions without its rotation, and it can be turned clockwise and counterclockwise every time outside the specified range, then measures at 5 positions. |
