| 摘要 |
PURPOSE:To eliminate an error in exposure due to the overshooting of sectors by varying the driving speed of a stepping motor which which opens and closes the sectors. CONSTITUTION:The period TL of driving pulses supplied to the stepping motor which moves the sectors in an opening direction is made variable in the preliminary rotation period t0-t1 of the stepping motor corresponding to a calculated exposure value. Then, the moving speed of the sectors when they move in the opening direction is varied and the quantity of overshooting also varies correspondingly. In this case, the stepping motor is supplied with driving pulses T0 having an invariably constant reference period so that the preset characteristics of programmed exposure are not disordered after the sectors begin to move and an exposure aperture is opened actually.
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