A low-cost sewing machine capable of achieving a desired balance between needle thread consumption and bobbin thread consumption is described. A memory section stores needle thread requirement data having precorrected needle thread requirement and postcorrected needle thread requirement. In a torque control zone, rotating force is imparted to a turning arm so as to impart a tension on the needle thread according to a torque value, while closing an upstream grip section main body and while opening a downstream grip section main body. In a first position control zone, the needle thread is drawn according to the postcorrected needle thread requirement, while opening the upstream grip section main body and while closing the downstream grip section. In a second position control zone, the turning arm is returned to an initial position, while closing the upstream grip section main body and while opening the downstream grip section main body.

A low-cost sewing machine capable of achieving a desired balance between needle thread consumption and bobbin thread consumption is described. A memory section stores needle thread requirement data having precorrected needle thread requirement and postcorrected needle thread requirement. In a torque control zone, rotating force is imparted to a turning arm so as to impart a tension on the needle thread according to a torque value, while closing an upstream grip section main body and while opening a downstream grip section main body. In a first position control zone, the needle thread is drawn according to the postcorrected needle thread requirement, while opening the upstream grip section main body and while closing the downstream grip section. In a second position control zone, the turning arm is returned to an initial position, while closing the upstream grip section main body and while opening the downstream grip section main body.

A sewing mechanism is provided with: a post bed and sewing needles, wherein an article to be sewn is interposed between the post bed and the sewing needles. When the post bed comes closer to the article to be sewn than that in the previous sewing by at least a predetermined distance, in other words, when a separation distance between the article to be sewn and the post bed becomes less than that in the previous sewing by at least a predetermined distance, a thread pulling mechanism pulls threads hooked in needle holes of the sewing needles in a direction away from the post bed.

A sewing mechanism is provided with: a post bed and sewing needles, wherein an article to be sewn is interposed between the post bed and the sewing needles. When the post bed comes closer to the article to be sewn than that in the previous sewing by at least a predetermined distance, in other words, when a separation distance between the article to be sewn and the post bed becomes less than that in the previous sewing by at least a predetermined distance, a thread pulling mechanism pulls threads hooked in needle holes of the sewing needles in a direction away from the post bed.

An embroidery apparatus is configured to perform an embroidery operation according to embroidery data. The embroidery apparatus includes a thread assumed consumption amount calculator configured to calculate an assumed consumption amount of a thread in the embroidery operation, based on initial embroidery data input in advance; a thread consumption amount detection mechanism configured to detect an actual consumption amount of the thread; and a thread consumption amount adjuster configured to adjust the actual consumption amount of the thread in the embroidery operation by adjusting output embroidery data to be output, based on a difference between the calculated assumed consumption amount of the thread and the detected actual consumption amount of the thread.

A lower thread supply device of a sewing machine includes a bobbin, a bobbin case, a magnetic force member, and a magnetic force change portion. The bobbin has a cylindrical portion for inserting into a spindle of a shuttle, a shuttle side flange portion, and a front surface side flange portion which is magnetic, and a lower thread is wound around an outer circumference of the cylindrical portion between the shuttle side flange portion and the front surface side flange portion. The bobbin case has a non-magnetic cover portion having a front surface side part and a side wall part, housing the bobbin and transmitting a magnetic force. The magnetic force member is arranged at the front surface side of the bobbin case and attracts the front surface side flange portion of the bobbin by a magnetic force via the bobbin case.

A lower thread supply device of a sewing machine includes a bobbin, a bobbin case, a magnetic force member, and a magnetic force change portion. The bobbin has a cylindrical portion for inserting into a spindle of a shuttle, a shuttle side flange portion, and a front surface side flange portion which is magnetic, and a lower thread is wound around an outer circumference of the cylindrical portion between the shuttle side flange portion and the front surface side flange portion. The bobbin case has a non-magnetic cover portion having a front surface side part and a side wall part, housing the bobbin and transmitting a magnetic force. The magnetic force member is arranged at the front surface side of the bobbin case and attracts the front surface side flange portion of the bobbin by a magnetic force via the bobbin case.

The present invention provides a thread feeding device of a decorative stitching sewing machine. The thread feeding device feeds a needle thread, an upper looper thread, and a lower looper thread in the amounts required for sewing one stitch such that the position of a stitch looping point of the threads changes. The thread feeding device includes: a thread accumulator 500 having thread accumulating elements 13a to 13d and 14a to 14d which measure the thread accumulation amounts of predetermined lengths of the needle thread, the upper looper thread, and the lower looper thread, and thread accumulation amount control elements 15 to 18 which adjust the amounts of the threads required for sewing one stitch in an increasable and decreasable manner within the range of thread accumulation amounts of predetermined lengths at the time of fabric feeding, and which release the threads to a stitch forming device when a stitch is formed; a thread feed drive mechanism 600 which drives each of the elements; and a thread feed control unit having a program which dives the thread accumulation amount control elements for each stitch to feed the threads in an increasable and decreasable manner so as to increase or decrease the threads within the range of a total thread feeding amount that is maintained constant, including a fabric feeding amount, a fabric thickness and an overlocking width, thereby to change the position of the stitch looping point of the needle thread, the upper looper thread, and the lower looper thread, thus controlling the decorative stitching according to a stitching decoration pattern.

The present invention provides a thread feeding device of a decorative stitching sewing machine. The thread feeding device feeds a needle thread, an upper looper thread, and a lower looper thread in the amounts required for sewing one stitch such that the position of a stitch looping point of the threads changes. The thread feeding device includes: a thread accumulator 500 having thread accumulating elements 13a to 13d and 14a to 14d which measure the thread accumulation amounts of predetermined lengths of the needle thread, the upper looper thread, and the lower looper thread, and thread accumulation amount control elements 15 to 18 which adjust the amounts of the threads required for sewing one stitch in an increasable and decreasable manner within the range of thread accumulation amounts of predetermined lengths at the time of fabric feeding, and which release the threads to a stitch forming device when a stitch is formed; a thread feed drive mechanism 600 which drives each of the elements; and a thread feed control unit having a program which dives the thread accumulation amount control elements for each stitch to feed the threads in an increasable and decreasable manner so as to increase or decrease the threads within the range of a total thread feeding amount that is maintained constant, including a fabric feeding amount, a fabric thickness and an overlocking width, thereby to change the position of the stitch looping point of the needle thread, the upper looper thread, and the lower looper thread, thus controlling the decorative stitching according to a stitching decoration pattern.

The present invention provides a thread feeding device of a decorative stitching sewing machine. The thread feeding device feeds a needle thread, an upper looper thread, and a lower looper thread in the amounts required for sewing one stitch such that the position of a stitch looping point of the threads changes. The thread feeding device includes: a thread accumulator 500 having thread accumulating elements 13a to 13d and 14a to 14d which measure the thread accumulation amounts of predetermined lengths of the needle thread, the upper looper thread, and the lower looper thread, and thread accumulation amount control elements 15 to 18 which adjust the amounts of the threads required for sewing one stitch in an increasable and decreasable manner within the range of thread accumulation amounts of predetermined lengths at the time of fabric feeding, and which release the threads to a stitch forming device when a stitch is formed; a thread feed drive mechanism 600 which drives each of the elements; and a thread feed control unit having a program which dives the thread accumulation amount control elements for each stitch to feed the threads in an increasable and decreasable manner so as to increase or decrease the threads within the range of a total thread feeding amount that is maintained constant, including a fabric feeding amount, a fabric thickness and an overlocking width, thereby to change the position of the stitch looping point of the needle thread, the upper looper thread, and the lower looper thread, thus controlling the decorative stitching according to a stitching decoration pattern.