Abstract: To provide a sewing machine that can control tension on a needle thread and tension on a bobbin thread on a per-stitch basis; that enables even heads of a multi-head embroidery sewing machine to form an identical embroidery; and that enables even a plurality of sewing machines to form identical embroidery. A memory device stores for each stitch of embroidery data a needle thread control torque value and a bobbin thread control torque value. In a needle thread torque control zone, an upstream grip section main body is closed, and a downstream grip section main body is opened. A needle thread motor is subjected to torque control in accordance with the needle thread control torque value. In the meantime, in a position control zone, the upstream grip section body is opened, and the downstream grip section body is closed, thereby subjecting the needle thread motor to position control.

Abstract: 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. 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.

Abstract: To provide a sewing machine that can control tension on a needle thread and tension on a bobbin thread on a per-stitch basis; that enables even heads of a multi-head embroidery sewing machine to form an identical embroidery; and that enables even a plurality of sewing machines to form identical embroidery. A memory device stores for each stitch of embroidery data a needle thread control torque value and a bobbin thread control torque value. In a needle thread torque control zone, an upstream grip section main body is closed, and a downstream grip section main body is opened. A needle thread motor is subjected to torque control in accordance with the needle thread control torque value. In the meantime, in a position control zone, the upstream grip section body is opened, and the downstream grip section body is closed, thereby subjecting the needle thread motor to position control.

Abstract: There is provided a sewing-machine bobbin thread tension controller capable of elaborately, accurately controlling bobbin thread tension without depending on frictional force. A bobbin thread tension controller includes an outer shuttle, a middle shuttle presser, a middle shuttle, a bobbin thread tension control mechanism, a shuttle actuation unit, and a bobbin. The middle shuttle has a magnet. A magnet is disposed, in close proximity to the magnet, on an arm attached to a rotary shaft of a shuttle actuation motor provided in the shuttle actuation unit. The middle shuttle is rotated by rotating the magnet by means of the motor. Further, a rotary disc is provided, in close proximity to the middle shuttle, on a rotary shaft of a bobbin thread tension control motor of the bobbin thread tension control mechanism and is provided with a magnet. A magnet is disposed on a part of the bobbin facing the rotary disc.

Abstract: 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. 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.

Abstract: There is provided a sewing-machine bobbin thread tension controller capable of elaborately, accurately controlling bobbin thread tension without depending on frictional force. A bobbin thread tension controller includes an outer shuttle 110, a middle shuttle presser 130, a middle shuttle 150, a bobbin thread tension control mechanism 200, a shuttle actuation unit 250, and a bobbin 300. The middle shuttle 150 has a magnet 190. A magnet 270 is disposed, in close proximity to the magnet 190, on an arm 260 attached to a rotary shaft of a shuttle actuation motor 252 provided in the shuttle actuation unit 250. The middle shuttle 150 is rotated by rotating the magnet 270 by means of the motor 252. Further, a rotary disc 210 is provided, in close proximity to the middle shuttle 150, on a rotary shaft of a bobbin thread tension control motor 202 of the bobbin thread tension control mechanism 200 and is provided with a magnet 214. A magnet is disposed on a part of the bobbin 300 facing the rotary disc 210.