| 摘要 |
PROBLEM TO BE SOLVED: To provide a device capable of accurately detecting travel abnormality of yarn such as a skip stitch of a sewing machine in a noncontact state.SOLUTION: This travel monitoring device 10 has a light source 14 for irradiating to the yarn 12 with the light L, a light receiving element 16 arranged in the opposite direction of the light source 14 to the yarn 12, and a control circuit 18 for determining the existence of travel of the yarn 12 from output of the light receiving element 16. The light receiving element 16 outputs a photoelectric current by photoelectrically converting the light L. Since the yarn 12 travels between the light source 14 and the light receiving element 16, a shadow of the yarn 12 is projected on the light receiving element 16. A value of the photoelectric current photoelectrically converted by the light receiving element 16 changes when the shadow of the yarn 12 changes. |
