| 摘要 |
PURPOSE:To perform high-accuracy positioning by generating position information on a stage by a laser length measuring instrument and generating a control signal to be fed back to an inch worm 11 through a closed loop on the basis of the position information. CONSTITUTION:The laser length measuring instrument 12 detects the current position of the inch worm 11 with high accuracy and sets the result in a current position counter 7. A subtracting circuit 8 finds the difference between the difference from the target position set in a target position counter 6 by a processor 5 and feeds it back to a control circuit 10 through the closed loop to control the inch worm 11. Consequently, the inch worm is positioned stably at a high speed with high accuracy and digital circuit is employed, so trouble for adjustments is eliminated.
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