POSITION ADJUSTING METHOD BETWEEN STOP PLATE AND STEPPING MOTOR

PURPOSE:To eliminate the need for an angle adjusting mechanism and to facili tate its adjusting operation by fixing the stop plate to an iris base plate at a reference position, and then adjusting the fitting angle of the stepping motor and fixing it. CONSTITUTION:Positioning holes are bored in the iris base plate 330 and stop plate 340 and a pin is inserted into those holes so as to fix the stop plate 340 to the iris base plate 330 at the specific reference position so that the stop plate is disabled to rotate. Then while the stepping motor 302 is driven, the motor 302 is rotated properly so that its output gear 303 and a following gear 310 engage each other, and the motor 302 is fixed with a stop screw 304. Thus, the reference position of the motor 302 is matched with the reference position of the plate 340 and then the pin for fixing the plate 340 to the base plate 330 in the unrotatable state is removed. Then when the motor 302 rotates, its rotary driving force is transmitted from a gear 302 arranged on its output shaft 302A to gears 310, 312, and 344 in order to rotate the plate 340.