ELECTRICALLY-DRIVEN ROTARY ACTUATOR

PROBLEM TO BE SOLVED: To securely remove a backlash even when gear precision is inferior.SOLUTION: A pair of driving-side spur gears 2, 3 are rotated by stepping motors 4, 5, and rotor shafts 4a, 5a of the pair of stepping motors 4, 5 are mutually set so that tooth faces thereof come into contact with tooth faces of a driven-side spur gear 1 mutually on the opposite side in a no-load state. The stepping motors 4, 5 are synchronously driven and the driven-side spur gear 1 is driven by the driving-side spur gears 2, 3 to mutually removes backlashes between the driving-side spur gears 2, 3 and the driven-side spur gear 1. In-phase coils 4A, 5a and 4B, 5B of the stepping motors 4, 5 are connected in series, and motor driving circuits 7A, 8A synchronously drive and rotate the rotor shafts 4a, 5a of the stepping motors 4, 5 while giving a predetermined phase difference. A rotary encoder 6 which detects rotations of only one of the stepping motors 4, 5 is attached to the stepping motor and then the driving-side spur gears 2, 3 have the mutual tooth faces brought into contact at the same place in a peripheral direction of the driven-side spur gear 1.