| 摘要 |
PURPOSE:To prevent jitter in the copy tip part without increment of the approach run length, by starting driving the optical system by a low-speed clutch and by switching this driving to driving dependent upon a main clutch after a short time. CONSTITUTION:Electromagnetic clutch 30 is used as the main clutch for contraction, and electromagnetic clutch 27 of a driving speed lower than electromagnetic clutch 30 is used as the low-speed clutch for clutch 30. For contraction, electromagnetic clutch 27 is turned on, and the first mirror in the optical system is started to be driven and is caused to rise, and after that, electromagnetic clutch 27 is turned off, and clutch 30 is turned on to rise the speed up to the speed dependent upon clutch 30. By transferring the control to constant-speed scanning dependent upon electromagnetic clutch 30 in this manner, a stable constant-speed state is obtained even for a short approach run length when the first mirror enters the effective image region. |
