| 摘要 |
[Problem] There is provided a needle thread tension controller that can control a magnitude of tension on a needle thread for each stitch, that can draw the needle thread with a slim chance of occurrence of a thread break, that easily, accurately detects occurrence of the thread break when the thread break has occurred, and that does not cause any excess or deficiency of a quantity of accumulated thread, which would otherwise be caused by drawing a needle thread. [Means for Resolution] There are provided an upstream grip section 40 and a downstream grip section 60 for gripping a needle thread and a turning section 80 for turning the needle thread. In a torque control zone, rotating force is imparted to a turning arm in accordance with a torque value while an upstream grip section main body 41 is closed and while a downstream grip section main body 61 is opened in such a way that tension is exerted on a needle thread against a direction in which a thread take-up lever 12a draws the needle thread. In the meantime, inaposition control zone, rotating force is imparted to the turning arm 81 in accordance with angle position data pertaining to a needle thread motor 86 while the upstream grip section main body 41 is opened and while the downstream grip section main body 61 is closed in such a way that an angle of the needle thread motor returns to an initial angle position of the needle thread motor 86. |
