| 摘要 |
<P>PROBLEM TO BE SOLVED: To detect stitch skipping without the need for adjusting sensitivity of a sensor and others even if a thickness, a kind and the like of a thread are changed, and without being affected by dust and the like. <P>SOLUTION: A sewing machine including: a needle bar 11 which is connected to a sewing machine upper shaft and is moved vertically; a shuttle which is rotated in an interlocking fashion with the sewing machine upper shaft to form a seam in an interlocking fashion with the needle bar; a stitch tension unit 4 which is arranged on the route from a bobbin to a balance and imparts tensile force to a needle thread; and a thread take-up spring 5 which is attached to the stitch tension unit, and swings between an initial position B and an operation position A by receiving the tensile force of the needle thread, and has a thread hooking part, comprises: detecting means 21 for detecting whether or not the thread take-up spring is located at the initial position B; and control means for detecting stitch skipping on the basis of the behavior detection of the thread take-up spring by the detecting means. The control means determines the stitch skipping on the basis of the detection of the initial position of the thread take-up spring 5 by the detecting means 21, within the range of a prescribed upper shaft angle (a balance bottom dead point+60°) from the balance bottom dead point, to output an alarm signal or stop the drive of the sewing machine. <P>COPYRIGHT: (C)2013,JPO&INPIT |
