| 摘要 |
PURPOSE:To avoid the deformation of a driving bar, by detecting the start of movement of a mobile stage and carrying out the control of speed when the movement is started. CONSTITUTION:The tip of a driving bar 3 is put into a groove 2 of a mobile stage 1 and does not move to the stage 1 when the movement is started in a low speed since the interval is long in the stop mode. A laser length measuring device 9 detects the extent of movement by means of a mobile mirror 7 and a fixed mirror 8 provided on the stage 1 but does not dwtect the novement yet at this moment. When the bar 3 touches the face A or B of the groove 2 and moves the stage 1, a laser beam 17a receives the modulation of frequency and detects the movement. This result of movement is recorded by a flip-flop 13, and thus a switch 10 is changed from the side C to D to change the speed from a low level to a high level. In such way, the deformation of the bar 3 can be avoided. |
