| 摘要 |
PROBLEM TO BE SOLVED: To prevent the step-out trouble at the start-up of a stepping motor rotating a slack prevention roller of a yarn slack preventing device of a yarn winder, etc. SOLUTION: A yarn slack preventing device 10 is placed at the upstream side of a winding means 12 for winding a yarn Y supplied from a spinning means 5 and the slack preventing roller 21 of the device is driven by a stepping motor 35. At the start of the rotation of the stepping motor 35, an excitation signal is outputted for a definite period by an excitation position fitting mode commanding part of a motor controlling means to fit the magnetic poles of the stator and the rotor with each other, a self-starting frequency is transmitted from a self-starting frequency holding commanding part and the frequency is maintained for a prescribed period to surely induce in a synchronized state. The counter-rotation and the step-out troubles at the start of the stepping motor 35 are prevented by the mechanism to enable sure synchronized rotation. The accurate control of rotation can be carried out by using a small-sized stepping motor having small torque even if the slack-prevention roller has a rather large inertia. COPYRIGHT: (C)2006,JPO&NCIPI
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