| 摘要 |
PURPOSE:To improve locating precision of the titled device by a method wherein a locating optical detector is provided inside and outside of two sides mutually adjoining pellet image developed in case a pellet is set on a correct position. CONSTITUTION:In case a pellet image 6 is overlapped only with 12 out of light receiving parts 10, 11 and 12 in X direction and the others 10, 11 on the right side are lighted, any data converted into electric signals are comparatively decided to shift the pellet image 6 rightward while in case the pellet image 6 is overlapped with the light receiving parts 11, 12 exluding 10, the data are decided to finish locating stopping a table. The locating in Y direction is simultaneously performed to shift two pellet images 6 upward stopping the table with the pellet image 6 overlapped with the other light receiving parts 14, 15 excluding 13. Any data on the other light receiving parts 16, 17 and 18 in theta direction are comparatively decided to turn the pellet image 6 clockwise locating in theta direction. |
