| 摘要 |
PURPOSE:To correct off-tracking by estimating the temperatures of the apparatus and ambient, estimating the corresponding off-tracking quantity based on the time hysteresis thereof and displacing the end of a carriage running rail in proportion to the estimated quantity thereof to the height direction. CONSTITUTION:Since the off-tracking quantity is determined by the temperature of the apparatus and ambient and their lapse with time, a PROM, etc. are built in so that the off-tracking quantity may be known from the temperatures having been measured several minutes to 10-odd minutes before and the current temperature and from the memory values thereof, the off-tracking quantity is digitally estimated, whereby a displacement element 12 consisting of an electrostrictive element or the like is driven. In this case, one end of the running rail 11 of a carriage 5 is changed for a slight quantity in the direction perpendicular to the carriage running direction by the displacemement element 12. Thereby, the off-tracking may be readily and accurately corrected. |
