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.

An overlock sewing machine includes: a looper cover detection member movable from non-switching to switching positions with looper cover open to closed state transition, with switching member operation switching the threading mechanism state to sewing-enabled after looper cover detection member movement to switching position; a side cover detection member movable from non-detection to detection positions with side cover open to closed state transition; and a lever coupled to the looper cover detection member and side cover detection member, switchable between states of pressing and not pressing the operating protrusion, following looper cover detection member and side cover detection member operating states. The lever is set to the pressing state upon movement of the looper cover detection member to switching position and of the side cover detection member to detection position.

An overlock sewing machine includes: a looper cover detection member movable from non-switching to switching positions with looper cover open to closed state transition, with switching member operation switching the threading mechanism state to sewing-enabled after looper cover detection member movement to switching position; a side cover detection member movable from non-detection to detection positions with side cover open to closed state transition; and a lever coupled to the looper cover detection member and side cover detection member, switchable between states of pressing and not pressing the operating protrusion, following looper cover detection member and side cover detection member operating states. The lever is set to the pressing state upon movement of the looper cover detection member to switching position and of the side cover detection member to detection position.

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.

With a overlock sewing machine, when a switching mechanism is switched to a threading-enabled state, and a looper cover is closed, the looper cover is slid toward one side in the hinge shaft axial direction so as to operate a detection lever. In the non-operating state, the detection lever is set to an initial position where it does not press an operation protrusion of a switch. When a side cover is closed, and the detection lever is operated, the operation lever is set to an operation-enabled position where it presses the operation protrusion. When the operation lever is operated, and the side cover is opened, the detection lever is set by passing through the operation-enabled to the operation-disabled position where it does not press the operation protrusion.

With a overlock sewing machine, when a switching mechanism is switched to a threading-enabled state, and a looper cover is closed, the looper cover is slid toward one side in the hinge shaft axial direction so as to operate a detection lever. In the non-operating state, the detection lever is set to an initial position where it does not press an operation protrusion of a switch. When a side cover is closed, and the detection lever is operated, the operation lever is set to an operation-enabled position where it presses the operation protrusion. When the operation lever is operated, and the side cover is opened, the detection lever is set by passing through the operation-enabled to the operation-disabled position where it does not press the operation protrusion.

An overlock sewing machine includes: a looper cover detection member movable from non-switching to switching positions with looper cover open to closed state transition, with switching member operation switching the threading mechanism state to sewing-enabled after looper cover detection member movement to switching position; a side cover detection member movable from non-detection to detection positions with side cover open to closed state transition; and a lever coupled to the looper cover detection member and side cover detection member, switchable between states of pressing and not pressing the operating protrusion, following looper cover detection member and side cover detection member operating states. The lever is set to the pressing state upon movement of the looper cover detection member to switching position and of the side cover detection member to detection position.

An overlock sewing machine includes: a looper cover detection member movable from non-switching to switching positions with looper cover open to closed state transition, with switching member operation switching the threading mechanism state to sewing-enabled after looper cover detection member movement to switching position; a side cover detection member movable from non-detection to detection positions with side cover open to closed state transition; and a lever coupled to the looper cover detection member and side cover detection member, switchable between states of pressing and not pressing the operating protrusion, following looper cover detection member and side cover detection member operating states. The lever is set to the pressing state upon movement of the looper cover detection member to switching position and of the side cover detection member to detection position.