Patent ID: 6213039
Filing Date: 2001-04-10
Classification: D05B

Abstract:
An apparatus for detecting thread breakage in a sewing machine which is provided with needles moving up and down to penetrate through a needle hole of a needle plate, a looper reciprocating laterally across the leading end of the needle, a thread take-up stand mounted on a sewing machine bed, a thread-controlling cam fixed on a rotary shaft interlocked with the reciprocal motion of the looper and changing in the extent of projection from the thread take-up stand according to rotation of the rotary shaft, and thread guides disposed on the thread take-up stand at both sides of the thread-controlling cam and having thread eyelets for inserting the looper thread, comprising:other thread guides having thread pass eyelets for inserting the looper thread fixed and disposed on the looper thread route between the thread-controlling cam and the looper, a thread breakage-detecting member for detecting presence or absence of vibration of looper thread inserted in the thread pass eyelets of other thread guides between the two thread guides, and a control circuit for stopping driving of the sewing machine on the basis of the detection of absence of thread vibration by this thread breakage-detecting member.